@article {2481, title = {Convergence Analysis of Distributed Set-Valued Information Systems}, journal = {IEEE Transactions on Automatic Control}, volume = {61}, year = {2016}, month = {06/2016}, pages = {1477 - 1491}, abstract = {
This paper focuses on the convergence of information in distributed systems of agents communicating over a network.
The information on which the convergence is sought is not represented by real numbers, as often in the literature, rather by sets. The dynamics of the evolution of information across the network is accordingly described by set-valued iterative maps. While the study of convergence of set-valued iterative maps is highly complex in general, this paper focuses on Boolean maps, which are comprised of arbitrary combinations of unions, intersections, and complements of sets. For these important class of systems, we provide tools to study both global and local convergence. A distributed geographic information system, leading to successful information reconstruction from partial and corrupted data, is used to illustrate the applications of the proposed methods.
}, keywords = {Embedded Control, Robotics}, doi = {10.1109/TAC.2015.2480176}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=7272075}, author = {A. Fagiolini and N. Dubbini and S. Martini and A. Bicchi} } @article {2207, title = {Epsilon{\textendash}optimal synthesis for vehicles with vertically bounded Field-Of-View}, journal = {IEEE Transactions on Automatic Control}, volume = {60}, year = {2015}, pages = {1204 - 1218}, abstract = {

This paper presents a contribution to the problem of obtaining an optimal synthesis for shortest paths for a unicycle guided by an on{\textendash}board limited Field Of{\textendash}View (FOV) sensor, which must keep a given landmark in sight. Previous works on this subject have provided an optimal synthesis for the case in which the FOV is limited in the horizontal directions (H{\textendash} FOV, i.e. left and right boundaries). In this paper we study the complementary case in which the FOV is limited only in the vertical direction (V{\textendash}FOV, i.e. upper and lower boundaries). With respect to the H{\textendash}FOV case, the vertical limitation is all but a simple extension. Indeed, not only the geometry of extremal arcs is different, but also a more complex structure of the synthesis is revealed by analysis. We will indeed show that there exist initial configurations for which the optimal path does not exist. In such cases, we provide an e{\textendash}optimal path whose length approximates arbitrarily well any other shorter path. Finally, we provide a partition of the motion plane in regions such that the optimal or e{\textendash}optimal path from each point in that region is univocally determined.

}, keywords = {Embedded Control, Robotics}, issn = {0018-9286}, doi = {10.1109/TAC.2014.2366271}, author = {Salaris, P. and Cristofaro, A. and L. Pallottino and A. Bicchi} } @conference {2223, title = {On Time-Optimal Trajectories for Differential Drive Vehicles with Field-Of-View Constraints}, booktitle = {IEEE Conference on Decision and Control (CDC2014)}, year = {2014}, pages = {2191 - 2197}, publisher = {IEEE}, organization = {IEEE}, address = {Los Angeles, USA, December 15-17}, abstract = {

This paper presents the first step toward the study of minimum time trajectories for a differential drive robot, which is equipped with a fixed and limited Field-Of-View (FOV) camera, towards a desired configuration while keeping a given landmark in sight during maneuvers. While several previous works have provided a complete synthesis of shortest paths in case of both nonholonomic and FOV constraints, to the best of our knowledge, this paper represents the first analysis of minimum time trajectories with the two constraints. After showing the extremals of the problem at hand, i.e. straight lines, rotations on the spot, logarithmic spirals and involute of circles, we provide the optimal control laws that steer the vehicle along the path and the cost in terms of time along each extremal. Moreover, we compare some concatenations of extremals in order to reduce the complexity of the problem toward the definition of a sufficient finite set of optimal maneuvers.

}, keywords = {Embedded Control, Robotics}, isbn = {978-1-4799-7746-8}, doi = {10.1109/CDC.2014.7039723}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=7039723}, author = {Cristofaro, A. and Salaris, P. and L. Pallottino and Giannoni, F. and A. Bicchi} } @conference {1583, title = {Packet-based dynamic control for nonlinear networked systems}, booktitle = {IEEE International Conference on Decision and Control (CDC2013)}, year = {2013}, pages = {6597,6603}, address = {Florence, Italy}, keywords = {Embedded Control, Robotics}, doi = {10.1109/CDC.2013.6760933}, author = {S. Falasca and M. Gamba and L. Greco and A. Chaillet and A. Bicchi} } @conference {1582, title = {Packet-Based Dynamic Control of a Furuta Pendulum over Ethernet}, booktitle = {Mediterranean Conference on Control and Automation (MED {\textquoteright}13)}, year = {2013}, month = {25-28 June 2013 }, pages = {464 - 470}, address = {Platanias-Chania, Crete, Greece}, abstract = {

This paper presents experimental results of the application of Packet-Based Control approach with dynamic controller on a real plant: the Furuta Pendulum. Despite its easiness of realization, Furuta Pendulum presents some features useful for our purposes, such as pretty non-linear dynamics, unstable equilibrium point and heavy dynamical inaccuracies. The network communication channel has been implemented using an Ethernet network. Packet-Based controller has been tested and compared with a classic local controller for different time-varying actuation delays. Results obtained corroborate the validity of the proposed architecture and highlight the robustness of this approach in the presence of actuation delays.

}, keywords = {Embedded Control, Robotics}, issn = {978-1-4799-0995-7}, doi = {10.1109/MED.2013.6608763}, url = {http://ieeexplore.ieee.org/xpl/articleDetails.jsp?tp=\&arnumber=6608763\&queryText\%3Dfalasca+gamba}, author = {T. Fabbri and D. Fenucci and S. Falasca and M. Gamba and A. Bicchi} } @article {1563, title = {On the Robust Synthesis of Logical Consensus Algorithms for Distributed Intrusion Detection}, journal = {Automatica}, volume = {49}, year = {2013}, pages = {2339 - 2350}, keywords = {Embedded Control, Robotics}, doi = {10.1016/j.automatica.2013.04.033}, author = {A. Fagiolini and A. Bicchi} } @conference {1788, title = {A Strategy for Dynamic Controller Emulation in Packet-Based Networked Control}, booktitle = {International Conference on Informatics in Control (ICINCO {\textquoteright}13)}, year = {2013}, pages = {29-38}, address = {Reykjav{\'\i}k, Iceland}, keywords = {Embedded Control, Robotics}, doi = {10.5220/0004427100290038}, author = {S. Falasca and M. Gamba and A. Bicchi} } @article {1232, title = {Interacting with networks: How does structure relate to controllability in single-leader, consensus networks?}, journal = {Control Systems Magazine}, volume = {32}, year = {2012}, pages = {66 - 73}, keywords = {Embedded Control, Robotics}, author = {M. Egerstedt and S. Martini and M. Cao and K. Camlibel and A. Bicchi} } @conference {MFB11, title = {Behavior classification, security, and consensus in societies of robots}, booktitle = {Automatica.it 2011}, year = {2011}, note = {

poster presentation

}, month = {September, 7 - 9}, address = {Pisa, Italy}, keywords = {Embedded Control, Robotics}, author = {S. Martini and A. Fagiolini and A. Bicchi} } @conference {MFZB11, title = {Decentralized Species Classification in Societies of Autonomous and Heterogenous Robots}, booktitle = {2011 IEEE International Conference on Robotics and Automation}, year = {2011}, month = {May 9 - 13}, pages = {32 - 39}, address = {Shangai, China}, keywords = {Embedded Control, Robotics}, author = {S. Martini and A. Fagiolini and G. Zichittella and M. Egerstedt and A. Bicchi} } @article {GFB11, title = {Design and Stability Analysis for Anytime Control via Stochastic Scheduling}, journal = {IEEE Trans. on Automat. Contr.}, volume = {56}, number = {3}, year = {2011}, pages = {571 - 585}, keywords = {Embedded Control, Robotics}, author = {L. Greco and D. Fontanelli and A. Bicchi} } @conference {GCB11, title = {Exploiting Packet Size in Uncertain Nonlinear Networked Control Systems}, booktitle = {2011 Congress of the International Federation of Automatic Control - IFAC 2011}, year = {2011}, month = {August 28 - Sept}, pages = {14404 - 14409}, address = {Milano, italy}, keywords = {Embedded Control, Robotics}, author = {L. Greco and A. Chaillet and A. Bicchi} } @conference {SPHB11, title = {From Optimal Planning to Visual Servoing with Limited FOV}, booktitle = {2011 IEEE/RSJ International Conference on Intelligent RObots and Systems}, year = {2011}, month = {September 25 - 3}, pages = {2817-2824}, address = {S. Francisco, USA}, keywords = {Embedded Control, Robotics}, author = {P Salaris and L. Pallottino and S. Hutchinson and A. Bicchi} } @conference {DMB11, title = {Left invertibility of output-quantized MISO linear systems}, booktitle = {2011 Congress of the International Federation of Automatic Control - IFAC2011}, year = {2011}, month = {August 28 - Sept}, pages = {11278 - 11283}, address = {Milano, italy}, abstract = {

This paper studies left invertibility of single-output discrete-time quantized linear systems. Quantized outputs are generated according to a given partition of the state-space, while inputs are sequences on a finite alphabet. Left invertibility deals with the possibility of recovering unknown inputs from the only knowledge of the outputs. It is reduced, under suitable conditions, to left D-invertibility: while left invertibility takes into account membership to sets of a given partition, left D-invertibility considers only membership to a single set, and is easily (and algorithmically) detectable. Our main result is a sufficient condition for the equivalence between left invertibility and left D-invertibility in MISO system. In unidimensional systems the equivalence is valid except at most a finite (and computable) number of cases. These results allows the effective detection of left invertibility by means of left Dinvertibility, which is algorithmically detectable. An example with effective computations is presented to show the application of the proposed method.

}, keywords = {Embedded Control, Robotics}, author = {N. Dubbini and M. Monge and A. Bicchi} } @booklet {11, title = {Optimal synthesis for nonholonomic vehicles with constrained side sensors}, year = {2011}, note = {

Technical Report

}, keywords = {Embedded Control, Robotics}, author = {P Salaris and L. Pallottino and A. Bicchi} } @conference {MDBGB11, title = {Robust Network Agreement on Logical Information}, booktitle = {2011 Congress of the International Federation of Automatic Control - IFAC 2011}, year = {2011}, month = {August 28 - Sept}, pages = {13905 - 13911}, address = {Milano, italy}, keywords = {Embedded Control, Robotics}, author = {S. Martini and D. Di Baccio and A. Fagiolini and A. Bicchi} } @conference {SPB11, title = {Shortest Paths With Side Sensor}, booktitle = {2011 IEEE International Conference on Robotics and Automation}, year = {2011}, month = {May 9 - 13}, pages = {4875 - 4882}, address = {Shangai, China}, keywords = {Embedded Control, Robotics}, author = {P Salaris and L. Pallottino and A. Bicchi} } @conference {BSB10, title = {3 known landmarks are enough for solving planar bearing SLAM and fully reconstruct unknown inputs}, booktitle = {Intelligent Robots and Systems (IROS), 2010 IEEE/RSJ International Conference on}, year = {2010}, month = {October}, pages = {2539 -2545}, address = {St. Louis MO USA}, keywords = {Embedded Control, Robotics}, doi = {10.1109/IROS.2010.5648896}, author = {F. A. W. Belo and P Salaris and A. Bicchi} } @article {MEB09, title = {Controllability analysis of multi-agent systems using relaxed equitable partitions}, journal = {Int. J. Systems, Control and Communications}, volume = {2}, number = {1,2,3}, year = {2010}, pages = {100-121}, abstract = {

This paper investigates the issue of how to make decentralised networks amenable to external control, i.e. how to ensure that they are appropriately organised so that they can be effectively

}, keywords = {Embedded Control, Robotics}, author = {S. Martini and M. Egerstedt and A. Bicchi} } @conference {WPB-ICRA10, title = {Controllability for Pairs of Vehicles Maintaining Constant Distance}, booktitle = {IEEE International Conference on Robotics and Automation (ICRA2010)}, year = {2010}, month = {May 3 - 8}, pages = {342 - 349}, address = {Anchorage, Alaska}, keywords = {Embedded Control, Robotics}, author = {H. Wang and L. Pallottino and A. Bicchi} } @conference {WPB_cdc10, title = {Controllability Properties for Aircraft Formations}, booktitle = {International Conference on Decision and Control - CDC 2010}, year = {2010}, pages = {2047 - 2054}, keywords = {Embedded Control, Robotics}, author = {H. Wang and L. Pallottino and A. Bicchi} } @conference {FBCABB-ICRA10, title = {Design and Control of a Novel 3D Casting Manipulator}, booktitle = {IEEE International Conference on Robotics and Automation (ICRA2010)}, year = {2010}, month = {May 3 - 8}, pages = {4169 - 4174}, address = {Anchorage, Alaska}, keywords = {Embedded Control, Robotics}, author = {A. Fagiolini and F. A. W. Belo and M. G. Catalano and S. Alicino and F. Bonomo and A. Bicchi} } @conference {CSB-ICRA10, title = {Design for Variable Stiffness Actuation based on Enumeration and Analysis of Performance}, booktitle = {IEEE International Conference on Robotics and Automation (ICRA2010)}, year = {2010}, month = {May 3 - 8}, pages = {3285 - 3291}, address = {Anchorage, Alaska}, keywords = {Embedded Control, Robotics}, author = {M. G. Catalano and R. Schiavi and A. Bicchi} } @article {QFGPB10, title = {Design of Embedded Controllers Based on Anytime Computing}, journal = {IEEE Trans. Industrial Infor.}, volume = {6}, number = {4}, year = {2010}, pages = {492 - 502}, abstract = {

In this paper, we present a methodology for designing embedded controllers based on the so-called anytime control paradigm. A control law is split into a sequence of subroutine calls, each one fulfilling a control goal and refining the result produced by the previous one. We propose a design methodology to define a feedback controller structured in accordance with this paradigm and show how a switching policy of selecting the controller subroutines can be designed that provides stability guarantees for the closed-loop system. The cornerstone of this construction is a stochastic model describing the probability of executing, in each activation of the controller, the different subroutines. We show how this model can be constructed for realistic real-time task sets and provide an experimental validation of the approach.

}, keywords = {Embedded Control, Robotics}, author = {A. Quagli and D. Fontanelli and L. Greco and L. Palopoli and A. Bicchi} } @conference {PCBB10, title = {Distributed Estimation and Detection under Local Information}, booktitle = {IFAC Workshop on Distributed Estimation and Control in Networked Systems}, year = {2010}, month = {Sept 13-14}, pages = {263-268}, address = {Annecy, France}, keywords = {Embedded Control, Robotics}, author = {F. Pasqualetti and R. Carli and A. Bicchi and F. Bullo} } @conference {PCBB, title = {Identifying Cyber Attacks via Local Model Information}, booktitle = {International Conference on Decision and Control - CDC 2010}, year = {2010}, month = {December}, pages = {5961 - 5966}, address = {Atlanta, USA}, keywords = {Embedded Control, Robotics}, author = {F. Pasqualetti and R. Carli and A. Bicchi and F. Bullo} } @article {DPB10, title = {Left invertibility of discrete systems with finite inputs and quantized output}, journal = {International Journal Of Control}, volume = {83}, number = {4}, year = {2010}, pages = {798 - 809}, abstract = {

The aim of this paper is to address left invertibility for dynamical systems with inputs and outputs in discrete sets. We study systems which evolve in discrete time within a continuous state-space; quantized outputs are generated by the system according to a given partition of the state-space, while inputs are arbitrary sequences of symbols in a finite alphabet, which are associated to specific actions on the system. Our main results are obtained under some contractivity hypotheses. The problem of left invertibility, i.e. recovering an unknown input sequence from the knowledge of the corresponding output string, is addressed using the theory of Iterated Function Systems (IFS), a tool developed for the study of fractals. We show how the IFS naturally associated to a system and the geometric properties of its attractor are linked to the invertibility property of the system. Our main result is a necessary and sufficient condition for left invertibility and uniform left invertibility for joint contractive systems. In addition, an algorithm is proposed to recover inputs from output strings. A few examples are presented to illustrate the application of the proposed method.

}, keywords = {Embedded Control, Robotics}, author = {N. Dubbini and B. Piccoli and A. Bicchi} } @conference {FBQB10, title = {A Modular and Layered Cosimulator for Networked Control Systems}, booktitle = {Mediterranean Conference on Control and Automation}, year = {2010}, month = {June, 23 - 25}, pages = {273 - 279}, address = {Marrakech, Morocco}, keywords = {Embedded Control, Robotics}, author = {S. Falasca and C Belsito and A. Quagli and A. Bicchi} } @conference {WPb_cdc10_2, title = {Motion planning for Formations of Dubins Vehicles}, booktitle = {International Conference on Decision and Control - CDC 2010}, year = {2010}, pages = {2263 - 2269}, keywords = {Embedded Control, Robotics}, author = {H. Wang and L. Pallottino and A. Bicchi} } @conference {FMEBG, title = {Observability and Controllability Detection of Multi-Agent Systems through Decentralized Laplacian Spectrum Estimation}, booktitle = {International Conference on Decision and Control - CDC 2010}, year = {2010}, pages = {5775 - 5780}, keywords = {Embedded Control, Robotics}, author = {M. Franceschelli and S. Martini and M. Egerstedt and A. Bicchi and A. Giua} } @conference {FMDBB10, title = {A Self-Routing Protocol for Distributed Consensus on Logical Information}, booktitle = {IEEE/RSJ International Conference on Intelligent Robots and Systems}, year = {2010}, month = {October, 18 - 22}, pages = {5151 - 5156}, address = {Taipei, Taiwan}, keywords = {Embedded Control, Robotics}, author = {A. Fagiolini and S. Martini and D. Di Baccio and A. Bicchi} } @article {SPFB10, title = {Shortest Paths for a Robot with Nonholonomic and Field-of-View Constraints}, journal = {IEEE Trans. on Robotics}, volume = {26}, number = {2}, year = {2010}, pages = {269 - 281}, keywords = {Embedded Control, Robotics}, author = {P Salaris and D. Fontanelli and L. Pallottino and A. Bicchi} } @conference {CGBSB10, title = {VSA-HD: From the Enumeration Analysis to the Prototypical Implementation}, booktitle = {IEEE/RSJ International Conference on Intelligent RObots and Systems}, year = {2010}, month = {October}, pages = {3676 - 3681}, address = {St. Louis MO USA}, keywords = {Embedded Control, Robotics}, author = {M. G. Catalano and G. Grioli and F. Bonomo and R. Schiavi and A. Bicchi} } @conference {QFGPB-ETFA09, title = {Designing Real-Time Embedded Controllers using the Anytime Computing Paradigm}, booktitle = {IEEE International Conference on Emerging Technology and Factory Automation}, year = {2009}, month = {September, 12 - }, pages = {1 - 8}, address = {Palma de Mallorca, Spain}, abstract = {

In this paper we present a methodology for designing embedded controllers with a variable accuracy. The adopted paradigm is the so called any-time control, which derives from the computing paradigm known as "imprecise computation". The most relevant contributions of the paper are a procedure for designing an incremental control law, whose different pieces cater for increasingly aggressive control requirements, and a modelling technique for the execution platform that allows us to design provably correct switching policies for the controllers. The methodology is validated by both simulations and experimental results.

}, keywords = {Embedded Control, Robotics}, doi = {10.1109/ETFA.2009.5347086}, author = {A. Quagli and D. Fontanelli and L. Greco and L. Palopoli and A. Bicchi} } @conference {FMDB-NecSys09, title = {Distributed Consensus on Boolean Information}, booktitle = {1st IFAC Workshop on Estimation and Control of Networked Systems (NecSys{\textquoteright}09)}, year = {2009}, month = {September, 24 - }, pages = {72 - 77}, address = {Venice, Italy}, abstract = {

In this paper we study the convergence towards consensus on information in a distributed system of agents communicating over a network. The particularity of this study is that the information on which the consensus is seeked is not represented by real numbers, rather by logical values or compact sets. Whereas the problems of allowing a network of agents to reach a consensus on logical functions of input events, and that of agreeing on set-valued information, have been separately addressed in previous work, in this paper we show that these problems can indeed be attacked in a unified way in the framework of Boolean distributed information systems. Based on a notion of contractivity for Boolean dynamical systems, a necessary and suficient condition ensuring the global convergence toward a unique equilibrium point is presented. This result can be seen as a first step toward the de nition of a unified framework to uniformly address all consensus problems on Boolean algebras.

}, keywords = {Embedded Control, Robotics}, author = {A. Fagiolini and S. Martini and N. Dubbini and A. Bicchi} } @conference {FBB-ICRA09, title = {Dynamic Distributed Intrusion Detection for Secure Multi-Robot Systems}, booktitle = {Int. Conference of Robotics and Automation}, year = {2009}, month = {May, 12 - 17}, pages = {2723 - 2728}, address = {Kobe, Japan}, keywords = {Embedded Control, Robotics}, author = {A. Fagiolini and F. Babboni and A. Bicchi} } @conference {SFB-ICRA09, title = {Integration of Active and Passive Compliance Control for Safe Human-Robot Coexistence}, booktitle = {Int. Conference of Robotics and Automation}, year = {2009}, month = {May, 12 - 17}, pages = {259 - 264}, address = {Kobe, Japan}, keywords = {Embedded Control, Robotics}, author = {R. Schiavi and F. Flacco and A. Bicchi} } @conference {DLFSB-IROS09, title = {Nonlinear Decoupled Motion-Stiffness Control and Collision Detection/Reaction for the VSA-II Variable Stiffness Device}, booktitle = {Proc. IEEE/RSJ International Conference on Intelligent RObots and Systems}, year = {2009}, month = {October, 11 - 15}, pages = {5487-5494}, address = {St. Louis MO USA}, abstract = {

Variable Stiffness Actuation (VSA) devices are being used to jointly address the issues of safety and performance in physical human-robot interaction. With reference to the VSA-II prototype, we present a feedback linearization approach that allows the simultaneous decoupling and accurate tracking of motion and stiffness reference profiles. The operative condition that avoids control singularities is characterized. Moreover, a momentum-based collision detection scheme is introduced, which does not require joint torque sensing nor information on the time-varying stiffness of the device. Based on the residual signal, a collision reaction strategy is proposed that takes advantage of the proposed nonlinear control to rapidly let the arm bounce away after detecting the impact, while limiting contact forces through a sudden reduction of the stiffness. Simulations results are presented to illustrate the performance of the overall approach. Extensions to the multi-dof case of robot manipulators equipped with VSA-II devices are also considered.

}, keywords = {Embedded Control, Physical Human-Robot Interaction (pHRI), Robotics}, author = {A. De Luca and F. Flacco and R. Schiavi and A. Bicchi} } @conference {FMDB-NESTER09, title = {Safety and Security in Networked Robotics Systems via Logical Consensus}, booktitle = {International Workshop on Networked embedded and control system technologies: European and Russian R\&D cooperation (NESTER{\textquoteright}09)}, year = {2009}, month = {July, 2 - 5}, address = {Milan, Italy}, keywords = {Embedded Control, Robotics}, author = {S. Martini and A. Fagiolini and G. Dini and A. Bicchi} } @conference {PBB-CDC09, title = {On the Security of Linear Consensus Networks}, booktitle = {Proc. IEEE International Conference on Decision and Control}, year = {2009}, note = {

General Chairs Recognition Awards for Interactive Papers

}, month = {December, 16 - 1}, pages = {4894 - 4901}, address = {Shangai, China}, abstract = {

The task of performing trustworthy computation in a network of autonomous agents in the presence of misbehaving components is the subject of this work. A solution to this problem is relevant for several coordination, formation, and synchronization tasks. Relying only on the information flow of the control protocol, uncooperative behaviors are revealed using an unknown input observer technique. Necessary and sufficient conditions to detect and correctly identify misbehaving nodes are given, together with a study of the genericity of such conditions. It is shown that generically any node of the network can correctly estimate the state of the other agents, and therefore compute any function of the state, provided that the connectivity of the communication graph is strictly greater than the number of misbehaving nodes. An intrusion detection and identification algorithm is described, and its effectiveness is confirmed through a numerical study.

}, keywords = {Embedded Control, Robotics}, author = {F. Pasqualetti and A. Bicchi and F. Bullo} } @conference {FMB-CASE09, title = {Set-Valued Consensus for Distributed Clock Synchronization}, booktitle = {Proc. IEEE Conference on Automation Science and Engineering}, year = {2009}, month = {August, 22-25}, pages = {116 - 121}, address = {Bangalore}, abstract = {

This paper addresses the clock synchronization problem in a wireless sensor network (WSN) and proposes a distributed solution that consists of a form of consensus, where agents are able to exchange data representing intervals or sets. The solution is based on a centralized algorithm for clock synchronization, proposed by Marzullo, that determines the smallest interval that is in common with the maximum number of measured interval. We first show how to convert such an algorithm into a problem involving only operations on sets, and then we convert it into a set

}, keywords = {Embedded Control, Robotics}, author = {A. Fagiolini and S. Martini and A. Bicchi} } @conference {PSFB-CDC09, title = {Shortest Paths for Non-holonomic Vehicles with Limited Field of View Camera}, booktitle = {Proc. IEEE International Conference on Decision and Control}, year = {2009}, month = {December, 16 - 1}, pages = {8434 - 8439}, address = {Shangai, China}, abstract = {

This paper presents a complete characterization of shortest paths for unicycle-like nonholonomic mobile robots equipped with a pinhole camera rigidly fixed with limited Field-Of-View (FOV). We preliminarily provide an alphabet of optimal control words and then we demonstrate how to obtain the partition induced by shortest path in the vehicle plane. The word univocally associated to a region encodes the shortest path from any starting point in that region to the goal point of the mobile robot without violating the FOV constraints.

}, keywords = {Embedded Control, Robotics}, author = {L. Pallottino and P Salaris and D. Fontanelli and A. Bicchi} } @article {FDSBB09, title = {Visual Servoing in the Large}, journal = {International Journal of Robotics Research}, volume = {28}, number = {6}, year = {2009}, month = {June}, pages = {802 - 814}, abstract = {

In this paper we consider the problem of maneuvering an autonomous robot in complex unknown environments using vision. The goal is to accurately servo a wheeled vehicle to a desired posture using only feedback from an on-board camera, taking into account the nonholonomic nature of the vehicle kinematics and the limited field-ofview of the camera. With respect to existing visual servoing schemes, which achieve similar goals locally (i.e. when the desired and actual camera views are sufficiently similar), we propose a method to visually navigate the robot through an extended visual map before eventually reaching the desired goal. The map comprises a set of images, previously stored in an exploratory phase, that convey both topological and metric information regarding the connectivity through feasible robot paths and the geometry of the environment, respectively. Experimental results on a laboratory setup are reported showing the practicality of the proposed approach.

}, keywords = {Embedded Control, Robotics}, author = {D. Fontanelli and A. Danesi and F. A. W. Belo and P Salaris and A. Bicchi} } @conference {GFB08, title = {Anytime Control Algorithms for Real-Time Embedded Systems}, booktitle = {Int Conf of Hybrid Systems: Computation and Control}, series = {Lecture Notes in Computer Science}, volume = {4981/2008}, year = {2008}, pages = {158 - 171}, publisher = {Springer-Verlag}, organization = {Springer-Verlag}, address = {St. Louis, MO}, abstract = {

In this paper we consider the problem of designing controllers for linear plants to be implemented in embedded platforms under stringent real-time constraints. These include preemptive scheduling schemes, under which the maximum execution time allowed for control software tasks is uncertain. We propose an {\textquoteleft}{\textquoteleft}anytime control{\textquoteright}{\textquoteright} design approach, consisting in a hierarchy of controllers for the same plant. Higher controllers in the hierarchy provide better closed-loop performance, while typically requiring a larger worst-case execution time. We provide a procedure for the design of controllers which, together with a conditioning process of the stochastic scheduling, provides better performance than prevailing worst case-based design, while guaranteeing almost sure stability of the resulting switching system.

}, keywords = {Embedded Control, Robotics}, author = {D. Fontanelli and L. Greco and A. Bicchi}, editor = {M. Egerstedt and B. Mishra} } @conference {FPVDB08, title = {Consensus-based Distributed Intrusion Detection for Multi-Robot Systems}, booktitle = {Proc. IEEE Int. Conf. on Robotics and Automation}, year = {2008}, pages = {120 - 127}, abstract = {

This paper addresses a security problem in robotic multi-agent systems, where agents are supposed to cooperate according to a shared protocol. A distributed Intrusion Detection System (IDS) is proposed here, that detects possible non- cooperative agents. Previous work by the authors showed how single monitors embedded on-board the agents can detect non- cooperative behavior, using only locally available information. In this paper, we allow such monitors to share the collected information in order to overcome their sensing limitation. In this perspective, we show how an agreement on the type of behavior of a target-robot may be reached by the monitors, through execution of a suitable consensus algorithm. After formulating a consensus problem over non-scalar quantities, and with a generic update function, we provide conditions for the consensus convergence and an upper bound to its transient duration. Effectiveness of the proposed solution is finally shown through simulation of a case study.

}, keywords = {Embedded Control, Robotics}, author = {A. Fagiolini and M. Pellinacci and M. Valenti and G. Dini and A. Bicchi} } @conference {MMB-CDC08, title = {Controllability Decompositions of Networked Systems Through Quotient Graphs}, booktitle = {Proc. IEEE Int. Conf. on Decision and Control}, year = {2008}, pages = {5244 - 5249}, keywords = {Embedded Control, Robotics}, author = {S. Martini and M. Egerstedt and A. Bicchi} } @conference {FTBD08, title = {Decentralized Deployment of Mobile Sensors for Optimal Connected Sensing Coverage}, booktitle = {Distributed Computing in Sensor Systems}, series = {Lecture Notes in Computer Science}, volume = {5067/2008}, year = {2008}, pages = {486 - 491}, publisher = {Springer Berlin / Heidelberg}, organization = {Springer Berlin / Heidelberg}, abstract = {

In this paper, we address the optimal connected sensing coverage problem, i.e., how mobile sensors with limited sensing capabilities can cooperatively adjust their locations so as to maximize the extension of the covered area while avoiding any internal "holes", areas that are not covered by any sensor. Our solution consists in a distributed motion algorithm that is based on an original extension of the Voronoi tessellation.

}, keywords = {Embedded Control, Robotics}, url = {http://dx.doi.org/10.1007/978-3-540-69170-9_34}, author = {A. Fagiolini and L. Tani and A. Bicchi and G. Dini} } @conference {CB-CDC08, title = {Delay compensation in packet-switching networked controlled systems}, booktitle = {Proc. IEEE Int. Conf. on Decision and Control}, year = {2008}, pages = {3620 - 3625}, keywords = {Embedded Control, Robotics}, author = {A. Chaillet and A. Bicchi} } @conference {MSVBB-CDC08, title = {Hybrid system reduction}, booktitle = {Proc. IEEE Int. Conf. on Decision and Control}, year = {2008}, pages = {227 -232}, keywords = {Embedded Control, Robotics}, author = {E. Mazzi and A. Sangiovanni Vincentelli and A. Balluchi and A. Bicchi} } @article {PB08, title = {Hypercubes are minimal controlled invariants for discrete-time linear systems with quantized scalar input}, journal = {Nonlinear Analysis. Hybrid systems}, number = {2}, year = {2008}, pages = {706-720}, abstract = {

Quantized linear systems are a widely studied class of nonlinear dynamics resulting from the control of a linear system through finite inputs. The stabilization problem for these models shall be studied in terms of the so called practical stability notion that essentially consists in confining the trajectories into sufficiently small neighborhoods of the equilibrium (ultimate boundedness) . In this paper, we study the problem of describing the smallest sets into which any feedback can ultimately confine the state, for a given linear single-input system with an assigned finite set of admissible input values (quantization). We show that a controlled invariant set of minimal size is contained in a family of sets (namely, hypercubes in controller-canonical form), previously introduced in [14, 15] . A comparison is presented which quantifies the improvement in tightness of the proposed analysis technique with respect to classical results using quadratic Lyapunov functions.

}, keywords = {Embedded Control, Robotics}, author = {B. Picasso and A. Bicchi} } @conference {DPB-CDC08, title = {Left invertibility of discrete systems with finite inputs and quantized output}, booktitle = {Proc. IEEE Int. Conf. on Decision and Control}, year = {2008}, pages = {4687 - 4692}, abstract = {

The aim of this paper is to address left invertibility for dynamical systems with inputs and outputs in discrete sets. We study systems that evolve in discrete time within a continuous state-space. Quantized outputs are generated by the system according to a given partition of the state-space, while inputs are arbitrary sequences of symbols in a finite alphabet, which are associated to specific actions on the system. We restrict to the case of contractive dynamics for fixed inputs. The problem of left invertibility, i.e. recovering an unknown input sequence from the knowledge of the corresponding output string, is addressed using the theory of Iterated Function Systems (IFS), a tool developed for the study of fractals. We show how the IFS naturally associated to a system and the geometric properties of its attractor are linked to the left invertibility property of the system. Our main results are a necessary and sufficient condition for a given system to be left invertible with probability one on the space of inputs (i.e. for almost all input sequences), and necessary and sufficient conditions for left invertibility and uniform left invertibility under some weak additional hypotheses. A few examples are presented to illustrate the application of the proposed method.

}, keywords = {Embedded Control, Robotics}, author = {N. Dubbini and B. Piccoli and A. Bicchi} } @conference {FVB-CDC08Ext, title = {Logical Consensus for Distributed Network Agreement}, booktitle = {Proc. IEEE Int. Conf. on Decision and Control}, year = {2008}, note = {

Extended Version

}, pages = {5250 - 5255}, keywords = {Embedded Control, Robotics}, author = {A. Fagiolini and E.M. Visibelli and A. Bicchi} } @conference {MED08-HTB, title = {Neural network based robust adaptive control for a variable stiffness actuator}, booktitle = {Control and Automation, 16 th Mediterranean Conference on Control and Automation}, year = {2008}, pages = {1028 - 1034}, abstract = {

In this paper we present a robust adaptive controller based on a neural network (NN) for a variable stiffness actuator (VSA). The controller is able to independently set the mechanical stiffness and position at the joint shaft to guarantee robustness with respect to slowly time-varying and unmodeled friction coefficients affecting the dynamics of the actuator. The lumped uncertainties of the VSA including unmodeled dynamics are considered and approximated by a simple NN so that the controlled system is asymptotically stable, and remains effective while process conditions vary. To cope with the reconstruction error of the NN, a sliding mode like additional robust control term is introduced. The proofs for the uniformly ultimately bounded (UUB) and uniform asymptotic (UAS) stabilities for the closed-loop system are provided in detail via Lyapunov theory. Simulation and experimental results are reported in support of both validity and performance of the proposed approach.

}, keywords = {Embedded Control, Robotics}, author = {S. Huh and G. Tonietti and A. Bicchi} } @conference {AMC08, title = {Physical Human-Robot Interaction: Dependability, Safety, and Performance}, booktitle = {Proc. 10th Intl. Workshop Advanced Motion Control}, year = {2008}, pages = {9-14}, abstract = {

In this paper we discuss the problem of achieving good performance in accuracy and promptness by a robot manipulator under the condition that safety is guaranteed throughout task execution. Intuitively, while a rigid and powerful structure of the arm would favor its performance, lightweight compliant structures are more suitable for safe operation. The quantitative analysis of the resulting design trade-off between safety and performance has a strong impact on how robot mechanisms and controllers should be designed for human-interactive applications. We discuss few different possible concepts for safely actuating joints, and focus on aspects related to the implementation of the mechanics and control of this new class of robots.

}, keywords = {Embedded Control, Physical Human-Robot Interaction (pHRI), Robotics}, author = {A. Bicchi and M. Bavaro and G. Boccadamo and D. De Carli and R. Filippini and G. Grioli and M. Piccigallo and A. Rosi and R. Schiavi and S. Sen and G. Tonietti} } @conference {PMB08, title = {Steering a Leader-Follower Team via Linear Consensus}, booktitle = {Hybrid Systems: Computation and Control}, series = {Lecture Notes in Computer Science}, volume = {4981/2008}, year = {2008}, pages = {642-645}, publisher = {Springer-Verlag}, organization = {Springer-Verlag}, abstract = {

The paper considers the problem of driving a formation of autonomous mobile agents. The group of mobile devices is described as a leader{\textendash}follower network, where the followers update their position using a simple local consensus procedure, while the leaders, whose positions represent the control inputs of the network, are free to move. We characterize the transient behavior of the network, and solve the containment problem without relying on auxiliary sensors.

}, keywords = {Embedded Control, Robotics}, author = {F. Pasqualetti and S. Martini and A. Bicchi}, editor = {M. Egerstedt and B. Mishra} } @conference {BFDS08, title = {Tolerating Malicious Monitors in Detecting Misbehaving Robots}, booktitle = {IEEE International Workshop on Safety, Security, and Rescue Robotics}, year = {2008}, pages = {108 - 114}, address = {Tohoku University Aobayama Campus, Sendai, Japan}, keywords = {Embedded Control, Robotics}, author = {A. Fagiolini and A. Bicchi and G. Dini and I. M. Savino} } @article {FSB08, title = {Toward Soft Robot you can Depend on}, journal = {IEEE Robotics and Automation Magazine}, volume = {15}, number = {3}, year = {2008}, pages = {31 - 41}, keywords = {Embedded Control, Robotics}, author = {R. Filippini and S. Sen and A. Bicchi} } @conference {GFB07, title = {Almost Sure Stability of Anytime Controllers via Stochastic Scheduling}, booktitle = {Proc. IEEE Int. Conf. on Decision and Control}, year = {2007}, month = {December}, pages = {5640-5645}, abstract = {

In this paper we consider scheduling the execution of a number of different software tasks implementing a hierarchy of real-time controllers for a given plant. Controllers are considered to be given and ordered according to a measure of the performance they provide. Software tasks implementing higher-performance controllers are assumed to require a larger worst-case execution time. Control tasks are to be scheduled within given availability limits on execution time, which change stochastically in time. The ensuing switching system is prone to instability, unless a very conservative policy is enforced of always using the simplest, least performant controller. The presented method allows to condition the stochastic scheduling of control tasks so as to obtain a better exploitation of computing capabilities, while guaranteeing almost sure stability of the resulting switching system.

}, keywords = {Embedded Control, Robotics}, author = {L. Greco and D. Fontanelli and A. Bicchi} } @conference {BDSP:ECC07, title = {A Component-Based Approach to Localization and Collision Avoidance for Mobile Multi-Agent Systems}, booktitle = {Proc. European Control Conference (ECC)}, year = {2007}, month = {July}, pages = {4285-4292}, abstract = {

In the RUNES project a disaster relief tunnel scenario is being developed in which mobile robots are used to restore the radio network connectivity in a stationary sensor network. A component-based software development approach has been adopted. Two components are described in this paper. A localization component that uses ultrasound and dead reckoning to decide the robot positions and a collision avoidance component that ensures that the robots do not collide with each other.

}, keywords = {Embedded Control, Robotics}, author = {P. Alriksson and J. Nordh and K -E Arz{\'e}n and A. Bicchi and A. Danesi and R. Schiavi and L. Pallottino} } @article {arz+07ejc, title = {A component-based approach to the design of networked control systems}, journal = {European Journal of Control}, volume = {13}, number = {2{\textendash}3}, year = {2007}, note = {

Invited paper

}, pages = {261-279}, abstract = {

Component-based techniques revolve around composable, reusable software objects that shield the application level software from the details of the hardware and lowlevel software implementation and vice versa. Components provide many benefits that have led to their wide adoption in software and middleware developed for embedded systems: They are well-defined entities that can be replaced without affecting the rest of the systems, they can be developed and tested separately and integrated later, and they are reusable. Clearly such features are important for the design of large-scale complex systems more generally, beyond software architectures. We propose the use of a component approach to address embedded control problems. We outline a general componentbased framework to embedded control and show how it can be instantiated in specific problems that arise in the control over/of sensor networks. Building on the middleware component framework developed under the European project RUNES, we develop a number of control-oriented components necessary for the implementation of control applications and design their integration. The paper provides the overview of the approach, discusses a real life application where the approach has been tested and outlines a number of specific control problems that arise in this application.

}, keywords = {Embedded Control, Robotics}, author = {K -E Arz{\'e}n and A. Bicchi and G. Dini and S. Hailes and K. H. Johansson and J. Lygeros and A. Tzes} } @article {PSFB06-TRO, title = {Decentralized cooperative policy for conflict resolution in multi-vehicle systems}, journal = {IEEE Trans. on Robotics}, volume = {23}, number = {6}, year = {2007}, pages = {1170-1183}, abstract = {

In this paper we propose a novel policy for steering multiple vehicles between assigned independent start and goal configurations and ensuring collision avoidance. The policy rests on the assumption that agents are all cooperating by implementing the same traffic rules. However, the policy is completely decentralized, as each agent decides its own motion by applying those rules only on locally available information, and totally scalable, in the sense that the amount of information processed by each agent and the computational complexity of the algorithms are not increasing with the number of agents in the scenario. The proposed policy applies to systems in which new vehicle may enter the scene and start interacting with existing ones at any time, while others may leave. Under mild conditions on the initial configurations, the policy is shown to be safe, i.e. to guarantee collision avoidance throughout the system evolution. In the paper, conditions are discussed on the desired configurations of agents under which the ultimate convergence of all vehicles to their goals can also be guaranteed. To show that such conditions are actually necessary and sufficient, which turns out to be a challenging liveness verification problem for a complex hybrid automaton, we employ a probabilistic verification method. The paper finally reports on simulations for systems of several tens of vehicles, and with some experimental implementation showing the practicality of the approach.

}, keywords = {Embedded Control, Robotics}, author = {L. Pallottino and V. G. Scordio and E. Frazzoli and A. Bicchi} } @conference {FVPDB:CDC07, title = {Decentralized Intrusion Detection for Secure Cooperative Multi-Agent Systems}, booktitle = {Proc. IEEE Int. Conf. on Decision and Control}, year = {2007}, pages = {1553-1558}, abstract = {

In this paper we address the problem of detecting faulty behaviors of cooperative mobile agents. A novel decentralized and scalable architecture that can be adopted to realize a monitor of the agents

}, keywords = {Embedded Control, Robotics}, author = {A. Fagiolini and G. Valenti and L. Pallottino and G. Dini and A. Bicchi} } @conference {PBB07, title = {Distributed intrusion detection for secure consensus computations}, booktitle = {Proc. IEEE Int. Conf. on Decision and Control}, year = {2007}, month = {December}, pages = {5594-5599}, abstract = {

This paper focuses on trustworthy computation systems and proposes a novel intrusion detection scheme for averaging networks with misbehaving nodes. This prototypical control problem is relevant in network security applications. The objective is for each node to detect and isolate the misbehaving nodes using only the information flow adopted by standard averaging protocols. We focus on the single misbehaving node problem. Our technical approach is based on the theory of Unknown Input Observability. First, we give necessary and sufficient conditions for the misbehavior to be observable and for the identity of the faulty node to be detectable. Second, we design a distributed unknown input estimator, and we characterize its convergence rate in the

}, keywords = {Embedded Control, Robotics}, author = {F. Pasqualetti and A. Bicchi and F. Bullo} } @conference {PB06, title = {A Dynamic Programming Approach to Optimal Planning for Vehicles with Trailers}, booktitle = {Proc. IEEE Int. Conf. on Robotics and Automation}, year = {2007}, pages = {3098 - 3103}, abstract = {

In this paper we deal with the optimal feedback synthesis problem for robotic vehicles with trailers which can be modeled by differential equations in chained-form. With respect to classical methods for numerical evolution of optimal feedback synthesis via Dynamic Programming which are based on both input and state discretization, our method exploits the lattice structure naturally imposed on the reachable set by input quantization. A generalized Dijkstra algorithm can be used to obtain optimal feedback control laws, for chained-form vehicles with n-trailers, in an effective way.

}, keywords = {Embedded Control, Robotics}, author = {L. Pallottino and A. Bicchi} } @article {MMMSS-07, title = {Hybrid Modeling and Control of the Common-Rail Injection System}, journal = {Int. J. Control}, volume = {80}, number = {11}, year = {2007}, pages = {1780 - 1795}, abstract = {We present an industrial case study in automotive control of significant complexity: the new common rail fuel injection system for Diesel engines, currently under production by Magneti Marelli Powertrain.In this system, an inlet metering valve, introduced before the High Pressure (HP) pump, regulates the fuel flow that supplies the common rail according to the engine operating point (e.g. engine speed, desired torque). The standard approach followed in automotive control is to use a mean{\textendash}value model for the plant and to develop a controller based on this model.I n this particular case, this approach does not provide a satisfactory solution as the discrete{\textendash}continuous interactions in the fuel injection system, due to the slow time{\textendash}varying frequency of the HP pump cycles and the fast sampling frequency of sensing and actuation, play a fundamental role.W e present a design approach based on a hybrid model of the Magneti Marelli Powertrain common{\textendash}rail fuel{\textendash}injection system for four-cylinder multi{\textendash}jet engines and a hybrid approach to the design of a rail pressure controller.T he hybrid controller is compared with a classical mean{\textendash}value based approach to automotive control design whereby the quality of the hybrid solution is demonstrated.}, keywords = {Automotive, Embedded Control}, author = {A. Balluchi and A. Bicchi and E. Mazzi and A. Sangiovanni-Vincentelli and G. Serra} } @conference {BBMSS-07, title = {Hybrid Multi-rate Control of the Common-Rail}, booktitle = {European Control Conference}, year = {2007}, pages = {54-61}, abstract = {

We present an industrial case study in automotive control of significant complexity: the new common-rail fuel- injection system for Diesel engines developed by Magneti Marelli Powertrain. In this system, an inlet metering valve, inserted before the High Pressure (HP) pump, regulates the fuel flow that supplies the common rail according to the engine operating point (e.g. engine speed and torque). The standard approach to controller design adopted in the automotive in- dustry is based on mean-value models of the plant. However, the fuel injection system exhibits complex discrete-continuous interactions, due to the slow time-varying frequency of the HP pump cycles and the fast sampling frequency of sensing and actuation. Hence, a hybrid approach to controller design is very promising. In this paper, we present the synthesis of a hybrid multi-rate controller for a Magneti Marelli Powertrain common-rail fuel- injection system for four-cylinder multi-jet engines. Controller design is based on a hybrid model of the injection system. The resulting hybrid controller performs significantly better then previous controllers developed in the company on the basis of mean-value models of the plant.

}, keywords = {Embedded Control, Robotics}, author = {A. Balluchi and A. Bicchi and E. Mazzi and A. Sangiovanni-Vincentelli and G. Serra} } @conference {FVPDB:CASE07, title = {Local Monitor Implementation for Decentralized Intrusion Detection in Secure Multi-Agent Systems}, booktitle = {3rd IEEE Conference on Automation Science and Engineering}, year = {2007}, pages = {454{\textendash}459}, abstract = {

This paper focuses on the detection of misbehaving agents within a group of mobile robots. A novel approach to automatically synthesize a decentralized Intrusion Detection System (IDS) as well as an efficient implementation of local monitors are presented. In our scenario, agents perform possibly different independent tasks, but cooperate to guarantee the entire system

}, keywords = {Embedded Control, Robotics}, author = {A. Fagiolini and G. Valenti and L. Pallottino and G. Dini and A. Bicchi} } @conference {PSFB07-ACC, title = {Probabilistic verification of decentralized multi-agent control strategies: a case study in conflict avoidance}, booktitle = {American Control Conference (ACC)}, year = {2007}, pages = {170-175}, abstract = {

Many challenging verification problems arise from complex hybrid automata that model decentralized control systems. As an example, we will consider decentralized policies that steer multiple vehicles in a shared environment: properties of safety and liveness, such as collision avoidance and ultimate convergence of all vehicles to their goals, must be verified. To formally verify the behavior of proposed policies, it is desired to identify the broadest class of start and goal configurations, such that safety and liveness would be guaranteed. Simple conditions are proposed to identify such a class: ideally, a formal proof that such conditions are necessary and sufficient for safety and liveness is requested. Unfortunately, in decentralized control frameworks classical approaches are difficult to apply. Hence, probabilistic verification method can be applied to quantify the accuracy and the confidence of the veridicity of the desired predicate. The probabilistic verification method is applied to a recently proposed cooperative and completely decentralized collision avoidance policy for non-holonomic vehicles.

}, keywords = {Embedded Control, Robotics}, author = {L. Pallottino and A. Bicchi and E. Frazzoli} } @article {PB07-TAC, title = {On the Stabilization of Linear Systems Under Assigned I/O Quantization}, journal = {IEEE Transactions on Automatic Control}, volume = {52}, number = {10}, year = {2007}, pages = {1994-2000}, abstract = {

This paper is concerned with the stabilization of discrete-time linear systems with quantization of the input and output spaces, i.e., when available values of inputs and outputs are discrete. Unlike most of the existing literature, we assume that how the input and output spaces are quantized is a datum of the problem, rather than a degree of freedom in design. Our focus is hence on the existence and synthesis of symbolic feedback controllers, mapping output words into the input alphabet, to steer a quantized I/O system to within small invariant neighborhoods of the equilibrium starting from large attraction basins. We provide a detailed analysis of the practical stabilizability of systems in terms of the size of hypercubes bounding the initial conditions, the state transient and the steady state evolution. We also provide an explicit construction of a practically stabilizing controller for the quantized I/O case.

}, keywords = {Embedded Control, Robotics}, author = {B. Picasso and A. Bicchi} } @conference {GFBP-07, title = {Steering Dynamical Systems with Finite Plans and Limited Path Length}, booktitle = {European Control Conference}, year = {2007}, pages = {4686-4690}, abstract = {

Complex dynamical systems can be steered by using symbolic input plans. These plans must have a finite descriptive length, and can be expressed by means of words chosen in an alphabet of symbols. In this way, such plans can be sent through a limited capacity channel to a remote system, where they are decoded in suitable control actions. The choice of this symbols is essential to efficiently encode steering plans. To this aim, in this paper, we state the problem of finding symbols maximizing the interval of points reachable by the system along paths with constrained length. We focus on the problem with two symbols, and compare the results with those produced by plans not accounting for the length constraint. Moreover, the behavior of a simple helicopter, steered by both kinds of plans, has been simulated, in order to illustrate the power of the overall control system, and to emphasize the improvements introduced by the new plans.

}, keywords = {Embedded Control, Robotics}, author = {L. Greco and A. Fagiolini and A. Bicchi and B. Piccoli} } @article {BBEFKP06, title = {Symbolic Planning and Control of Robot Motion: Finding the Missing Pieces of Current Methods and Ideas}, journal = {Robotics and Automation Magazine}, volume = {14}, number = {1}, year = {2007}, pages = {61-70}, abstract = {

Approaches to robot motion planning and control that involve tools such as automata, languages, temporal logics, and grammars, have been recently termed "symbolic." In this article, we review some existing results, discuss their relevance and applicability, and outline some of the main open questions and challenges in the area.

}, keywords = {Embedded Control, Robotics}, author = {C. Belta and A. Bicchi and M. Egerstedt and E. Frazzoli and E. Klavins and G. J. Pappas} } @conference {FontanelliVGCB06, title = {Adaptive non Linear Control of Dynamic Mobile Robots with Parameters Uncertainty}, booktitle = {Int. IFAC Symp. on Robot Control}, year = {2006}, month = {September}, address = {Bologna, Italy}, abstract = {

Research of a modular stabilizing control law for uncertain, nonholonomic mobile systems with actuators limitation has been investigated. Modular design allows the definition of a stabilizing control law for the kinematic model. The presence of uncertainties in the actuators parameters or in the vehicle dynamics has been treated both adding suitable components to the Lyapunov function and using parameters adaptation laws (e.g. adaptive control and backstepping techniques). Simulations are reported for the set point stabilization of a unicycle like vehicle showing the feasibility of the proposed approach. Torque limitations for a unicycle like vehicle has been investigated using backstepping techniques for the vehicle tracking problem. Simulations are reported.

}, keywords = {Embedded Control, Robotics}, author = {D. Fontanelli and R. Viviani and L. Greco and A. Caiti and A. Bicchi} } @inbook {B06, title = {Controllo, Teoria del}, booktitle = {Enciclopedia Italiana di Scienze, Lettere ed Arti}, year = {2006}, publisher = {Istituto della Enciclopedia Italiana {\textquoteleft}{\textquoteleft}G. Treccani{\textquoteright}{\textquoteright}}, organization = {Istituto della Enciclopedia Italiana {\textquoteleft}{\textquoteleft}G. Treccani{\textquoteright}{\textquoteright}}, edition = {XXI Secolo {\textendash} Aggiornamento}, keywords = {Embedded Control, Robotics}, author = {A. Bicchi} } @conference {PSFB-MTNS06, title = {Decentralized and scalable conflict resolution strategy for multi-agents systems}, booktitle = {Int. Symp. on Mathematical Theory of Networks and Systems}, year = {2006}, abstract = {

A decentralized cooperative collision avoidance control policy for planar vehicle recently proposed is herein considered. Given some simple conditions on initial configurations of agents, the policy is known to ensure safety (i.e., collision avoidance) for an arbitrarily large number of vehicles. The method is highly scalable, and effective solutions can be obtained for several tens of autonomous agents. On the other hand, the liveness property of the policy, i.e. the capability of negotiating a solution in finite time, is not yet completely understood. First a 3D workspace extension is proposed. Furthermore, based on a condition on target configuration previously proposed, some general results on the liveness property are reported. Finally, qualitative evaluations on the strategy and on the proposed target sparsity condition are pointed out.

}, keywords = {Embedded Control, Robotics}, author = {L. Pallottino and V. G. Scordio and E. Frazzoli and A. Bicchi} } @conference {CACSD06, title = {On the Design and Control of Wireless Networked Embedded Systems}, booktitle = {Int. Conf. on Computer Aided Control System Design - CACSD{\textquoteright}06}, year = {2006}, pages = {440-445}, publisher = {IEEE}, organization = {IEEE}, abstract = {

Wireless networked embedded systems are becoming increasingly important in a wide area of technical fields. In this tutorial paper we present recent results on design and control of these systems developed within the project Reconfigurable Ubiquitous Networked Embedded Systems (RUNES), which is an European Integrated Project with the aim to control complexity in networked embedded systems by developing robust and scalable middleware systems. New components for control under varying network conditions are discussed for the RUNES architecture. The complexity of the closed-loop system is increased due to the coupling with the disturbances introduced by the communication system. The network may introduce additional delays, jitter, data rate limitations, packet losses etc. Experimental work on integration test beds that demonstrates these results is shown together with motivating links to the RUNES disaster relief tunnel scenario.

}, keywords = {Embedded Control, Robotics}, author = {K -E Arz{\'e}n and A. Bicchi and S. Hailes and K. H. Johansson and J. Lygeros} } @article {BBMP-TAC06, title = {Feedback Encoding for Efficient Symbolic Control of Dynamical Systems}, journal = {IEEE Trans. on Automatic Control}, volume = {51}, number = {6}, year = {2006}, pages = {1-16}, abstract = {

The problem of efficiently steering dynamical systems by generating finite input plans is considered. Finite plans are finite{\textendash}length words constructed on a finite alphabet of input symbols, which could be e.g. transmitted through a limited capacity channel to a remote system, where they can be decoded in suitable control actions. Efficiency is considered in terms of the computational complexity of plans, and in terms of their description length (in number of bits). We show that, by suitable choice of the control encoding, finite plans can be efficiently built for a wide class of dynamical systems, computing arbitrarily close approximations of a desired equilibrium in polynomial time. The paper also investigates how the efficiency of planning is affected by the choice of inputs, and provides some results as to optimal performance in terms of accuracy and range.

}, keywords = {Embedded Control, Robotics}, author = {A. Bicchi and A. Marigo and B. Piccoli} } @conference {BBMSS06, title = {Hybrid Modelling and Control of the Common Rail Injection System}, booktitle = {Hybrid Systems: Computation and Control}, series = {Lecture Notes in Computer Science}, volume = {3927 / 2006}, year = {2006}, pages = {79-92}, publisher = {Springer-Verlag}, organization = {Springer-Verlag}, abstract = {

We present an industrial case study in automotive control of significant complexity: the new common rail fuel injection system for Diesel engines, currently under production by Magneti Marelli Powertrain. In this system, a flow-rate valve, introduced before the High Pressure (HP) pump, regulates the fuel flow that supplies the common rail according to the engine operating point. The standard approach followed in automotive control is to use a mean-value model for the plant and to develop a controller based on this model. In this particular case, this approach does not provide a satisfactory solution as the discrete-continuous interactions in the fuel injection system, due to the slow time-varying frequency of the HP pump cycles and the fast sampling frequency of sensing and actuation, play a fundamental role. We present a design approach based on a hybrid model of the Magneti Marelli Powertrain common-rail fuel-injection system for four-cylinder multi-jet engines and a hybrid approach to the design of a rail pressure controller. The hybrid controller is compared with a classical mean-value based approach to automotive control design whereby the quality of the hybrid solution is demonstrated.

}, keywords = {Embedded Control, Robotics}, author = {A. Balluchi and A. Bicchi and E. Mazzi and A. Sangiovanni Vincentelli and G. Serra}, editor = {J. Hespanha and A. Tiwari} } @conference {BMP06-HSCC, title = {Improving efficiency of finite plans by optimal choice of input sets}, booktitle = {Hybrid Systems: Computation and Control}, series = {Lecture Notes in Computer Science}, volume = {3927 / 2006}, year = {2006}, pages = {108-122}, publisher = {Springer-Verlag}, organization = {Springer-Verlag}, abstract = {

Finite plans proved to be an efficient method to steer complex control systems via feedback quantization. Such finite plans can be encoded by finite{\textendash}length words constructed on suitable alphabets, thus permitting transmission on limited capacity channels. In particular flat systems can be steered computing arbitrarily close approximations of a desired equilibrium in polynomial time. The paper investigates how the efficiency of planning is affected by the choice of inputs, and provides some results as to optimal performance in terms of accuracy and range. Efficiency is here measured in terms of computational complexity and description length (in number of bits) of finite plans.

}, keywords = {Embedded Control, Robotics}, author = {A. Bicchi and A. Marigo and B. Piccoli}, editor = {J. Hespanha and A. Tiwari} } @conference {PB06, title = {Practical stabilization of LTI SISO systems under assigned Input and Output quantization}, year = {2006}, note = {

ADHS{\textquoteright}06

}, month = {July}, pages = {353-358}, abstract = {

This work is concerned with the practical stabilization of discrete{\textendash}time SISO linear systems under assigned quantization of the input and output spaces. A controller is designed which guarantees effective practical stability properties. Unlike most of the existing literature, quantization is supposed to be a problem datum rather than a degree of freedom in design. Moreover, in the framework of control under assigned quantization, results are concerned with state quantization only and do not include the quantized output feedback case considered here. While standard stability analysis techniques are based on Lyapunov theory and invariant ellipsoids, our study of the closed loop dynamics involves a particularly suitable family of sets, which are hypercubes in controller form coordinates.

}, keywords = {Embedded Control, Robotics}, author = {B. Picasso and A. Bicchi} } @conference {PSFB06, title = {Probabilistic verification of a decentralized policy for conflict resolution in multi-agent systems}, booktitle = {Proc. IEEE Int. Conf. on Robotics and Automation}, year = {2006}, note = {

Correct version

}, pages = {2448-2453}, abstract = {

In this paper, we consider a decentralized cooperative control policy proposed recently for steering multiple non-holonomic vehicles between assigned start and goal configurations while avoiding collisions. The policy is known to ensure safety (i.e., collision avoidance) for an arbitrarily large number of vehicles, if initial configurations satisfy certain conditions. The method is highly scalable, and effective solutions can be obtained for several tens of autonomous agents. On the other hand, the liveness property of the policy, i.e. the capability of negotiating a solution in finite time, is not yet completely understood. In this paper, we introduce a condition on the final vehicle configurations, which we conjecture to be sufficient for guaranteeing liveness. Because of the overwhelming complexity of proving the sufficiency of such condition, we assess the correctness of the conjecture in probability through the analysis of the results of a large number of randomized experiments.

}, keywords = {Embedded Control, Robotics}, author = {L. Pallottino and V. G. Scordio and E. Frazzoli and A. Bicchi} } @conference {DFPSSDB06, title = {A scalable platform for safe and secure decentralized traffic management of multiagent mobile systems}, booktitle = {ACM Workshop on Real-World Wireless Sensor Networks}, year = {2006}, abstract = {

In this paper we describe the application of wireless sensor networking techniques to address the realization of a safe and secure decentralized traffic management system. We consider systems of many heterogeneous autonomous vehicles moving in a shared environment. Each vehicle is assumed to have different and possibly unspecified tasks, but they cooperate to avoid collisions. We are interested in designing a scalable architecture capable of accommodating a very large and dynamically changing number of vehicles, guaranteeing their safety (i.e., collision avoidance), the achievement of their goals, and security against potential adversaries. By properly distributing and revoking cryptographic keys we are able to protect communications from an external adversary as well as to detect non-cooperative, possibly malicious vehicles and trigger suitable countermeasures. In our architecture, scalability is obtained by decentralization, i.e. each vehicle is regarded as an autonomous agent capable of processing information concerning its own state and the state of only a fixed, small number of {\textquoteleft}{\textquoteleft}neighboring{\textquoteright}{\textquoteright} agents. Ad-hoc wireless sensor networks are employed to provide support for this architecture.

}, keywords = {Embedded Control, Robotics}, author = {A. Danesi and A. Fagiolini and I. Savino and L. Pallottino and R. Schiavi and G. Dini and A. Bicchi} } @conference {DSSBG06, title = {Security and Advanced Control Issues in a Robotic Platform for Monitoring and Relief}, booktitle = {Proc. of EWSN 2006 February 13-15, ETH Zurich}, year = {2006}, abstract = {

This paper provides an architectural overview and a first implementation of an heterogeneous agent network composed by mobile robots of di

}, keywords = {Embedded Control, Robotics}, author = {A. Danesi and I. M. Savino and R. Schiavi and A. Bicchi and G. Dini} } @conference {FGBPM06, title = {Symbolic Control for Underactuated Differentially Flat Systems}, booktitle = {Proc. IEEE Int. Conf. on Robotics and Automation}, year = {2006}, pages = {1649-1654}, abstract = {

In this paper we address the problem of generating input plans to steer complex dynamical systems in an obstacle-free environment. Plans considered admit a finite description length and are constructed by words on an alphabet of input symbols, which could be e.g. transmitted through a limited capacity channel to a remote system, where they can be decoded in suitable control actions. We show that, by suitable choice of the control encoding, finite plans can be efficiently built for a wide class of dynamical systems, computing arbitrarily close approximations of a desired equilibrium in polynomial time. Moreover, we illustrate by simulations the power of the proposed method, solving the steering problem for two examples in the class of underactuated systems, which have attracted wide attention in the recent literature.

}, keywords = {Embedded Control, Robotics}, author = {A. Fagiolini and L. Greco and A. Bicchi and B. Piccoli and A. Marigo} } @booklet {BCFGV05, title = {Adaptive nonlinear control of dynamic mobile robots with parameters uncertainty}, year = {2005}, publisher = {Dipartimento di Sistemi Elettrici e Automazione, Universit\à di Pisa}, abstract = {

Research of a modular stabilizing control law for uncertain, nonholonomic mobile systems with actuators limitation has been investigated. Modular design allows the definition of a stabilizing control law for the kinematic model. The presence of uncertainties in the actuators parameters or in the vehicle dynamics has been treated both adding suitable components to the Lyapunov function and using parameters adaptation laws (e.g. adaptive control and backstepping techniques). Simulations are reported for the set point stabilization of a unicycle like vehicle showing the feasibility of the proposed approach. Torque limitations for a unicycle like vehicle has been investigated using backstepping techniques for the vehicle tracking problem. Simulations are reported.

}, keywords = {Embedded Control, Robotics}, author = {A. Bicchi and A. Caiti and D. Fontanelli and L. Greco and R. Viviani} } @article {PB04-rendi, title = {Control synthesis for practical stabilization of quantized linear systems}, journal = {Rend. Sem. Mat. Univ. Pol. Torino, Control Theory and Stabil., I}, volume = {63}, number = {4}, year = {2005}, pages = {397{\textendash}410}, abstract = {

In this work we face the stability problem for quantized control systems (QCS). A discrete{\textendash}time single{\textendash}input linear model is considered and, motivated by technological applications, we assume that a uniform quantization of the control set is a priori fixed. As it is well known, for QCS only practical stability properties can be achieved, therefore we focus on the existence and construction of quantized controllers capable of steering a system to within invariant neighborhoods of the equilibrium. The main contribution of the paper consists in a theorem which provides a condition for the practical stabilization in a fixed number of steps: not only the result is interesting in itself, but also it enables to construct a family of stabilizing controllers by means of Model Predictive Control (MPC) techniques. In the last part of the paper some results on the characterization of controlled{\textendash}invariant sets are reviewed and a lower bound on the size of invariant sets is provided.

}, keywords = {Embedded Control, Robotics}, author = {B. Picasso and A. Bicchi} } @conference {PSFB05, title = {Decentralized Cooperative Conflict Resolution for Multiple Nonholonomic Vehicles}, booktitle = {Proc. AIAA COnf. on Guidance, Navigation and Control}, year = {2005}, abstract = {

In this paper, we consider the problem of collision-free motion planning for multiple nonholonomic planar vehicles. Each vehicle is capable of moving at constant speed along paths with bounded curvature, and is aware of the position and heading of other vehicles within a certain sensing radius. No other information exchange is required between vehicles. We propose a spatially decentralized, cooperative hybrid control policy that ensures safety for arbitrary numbers of vehicles. Furthermore, we show that under certain conditions, the policy avoids dead- and livelock, and eventually all vehicles reach their intended targets. Simulations and experimental results are presented and discussed.

}, keywords = {Embedded Control, Robotics}, author = {L. Pallottino and V. G. Scordio and E. Frazzoli and A. Bicchi} } @conference {BGGT05, title = {Hybrid Modelling of an Electronically Controlled Limited Slip Differential}, year = {2005}, month = {8-10 September}, keywords = {Embedded Control, Robotics}, author = {A. Bicchi and G. Greco and M. Guiggiani and G. Tonietti} } @article {PPBSV03, title = {Maximizing the stability radius of a set of systems under real-time scheduling constraints}, journal = {IEEE Trans. on Automatic Control}, volume = {50}, number = {11}, year = {2005}, month = {November 2005}, pages = {1790{\textendash}1795}, abstract = {

We address the problem of synthesising real-time embedded controllers taking into account constraints deriving from the implementation platform. Assuming a time-triggered model of computation for tasks controlling a set of independent systems and a real-time preemptive scheduling policy managing a single CPU processor board, we deal with two problems: 1- deciding whether a performance specification can be met on a given platform, 2- optimising performance on a platform. Decision variables of the design problems are the activation periods of the tasks , while the considered performance metric is the minimum stability radius attained over the different feedback loops, which is related to the technological feasibility of the controller and to the robustness of the controlled systems. The analytical formulation of the design problems enables efficient numerical solutions. The resulting control policies are directly implementable without performance degradation that may otherwise arise due to scheduling and execution delays.

}, keywords = {Embedded Control, Robotics}, author = {L. Palopoli and C. Pinello and A. Bicchi and A. L. Sangiovanni-Vincentelli} } @article {BSB04, title = {Path-Following with a Bounded-Curvature Vehicle: a Hybrid Control Approach}, journal = {International Journal of Control}, volume = {78}, number = {15}, year = {2005}, month = {October}, pages = {1228-1247}, abstract = {

In this paper, we consider the problem of stabilizing the kinematic model of a car to a path in the plane under rather general conditions. The path is subject to very mild restrictions, while the car model, although rather simplified, contains the most relevant limitations inherent in wheeled robots kinematics. Namely, the car can only move forward, its steering radius is lower bounded and a limited sensory information only provides a partial knowledge of some state parameters. In particular, we consider the case that the current distance and the heading angle error with respect to the closest point on the reference path can be measured but only the sign of the path curvature is detected. These constraints are such to make classical control techniques inefficient. As the feedback information is both continuous and discrete, the hybrid systems formalism turns out to be well appropriate to model the problem. The proposed approach is based on optimal control techniques successfully applied in a previous work for following rectilinear path. We propose here an extension to the tracking of more general paths with moderate curvature. The stability of the closed-loop system is proved by means of the hybrid system formalism and hybrid formal verification techniques. Finally, the practicality of the proposed approach, in spite of non{\textendash}idealities in real-world applications, is discussed by reporting experimental results.

}, keywords = {Embedded Control, Robotics}, author = {A. Balluchi and A. Bicchi and P. Sou{\`e}res} } @conference {ABBPSZ05, title = {Randomized Algorithms for Platform{\textendash}based Design}, booktitle = {Proc. IEEE Int. Conf. on Decision and Control}, year = {2005}, pages = {6638 - 6643}, abstract = {

The design of automotive control systems is becoming increasingly complex as the level of performance required by car manufactures grows continuously and the constraints on cost and development time imposed by the market become tighter. A successful design, without costly and time consuming re-design cycles, can be achieved only by using an efficient design methodology that allows for component re-use and evaluation of platform requirements at the early stages of the design flow. In this paper, we illustrate a control-implementation design methodology for the development of embedded controllers by composition of algorithms picked up from libraries. Randomized algorithms and hybrid system theory are used to develop techniques for functional and architecture evaluations, which are implemented in a prototype tool.

}, keywords = {Embedded Control, Robotics}, author = {A. Agostini and A. Balluchi and A. Bicchi and B. Piccoli and Sangiovanni Vincentelli, A. and K. Zadarnowska} } @conference {PPBJ04, title = {Control of Distributed Embedded Systems in the Presence of Unknown{\textendash}but{\textendash}Bounded Noise}, booktitle = {Proc. IEEE Int. Conf. on Decision and Control}, year = {2004}, pages = {1448-1453}, abstract = {

In this paper we consider the problem of controlling multiple scalar systems through a limited capacity shared channel. Each system is affected by process noise and can be controlled byactuators with values in a {\em fixed}inite set. The control objective is to bound the evolution of the systems in specified sets (controlled invariance). Our goal is to find an optimal allocation of the shared communication resource to the different control activities and to identify correct choices for the design parameters. The paper provides fundamental conceptual tools to attack the design problem in the formal framework of an optimization problem. Namely, we give a feasibility criterion to decide whether a set of design parameters conforms with a control specification (i.e., with the controlled invariance of a specified set for each system). Moreover, we offer the explicit computation of the minimum bit rate necessary for the controlled invariance of a set, which is of utmost importance for solving the optimization problem.

}, keywords = {Embedded Control, Robotics}, author = {B. Picasso and L. Palopoli and A. Bicchi and K. H. Johansson} } @conference {PSB04, title = {Decentralized Cooperative Conflict Resolution Among Multiple Autonomous Mobile Agents}, booktitle = {cdc}, year = {2004}, pages = {4758-4763}, abstract = {

In this paper we consider policies for cooperative, decentralized traffic management among a number of autonomous mobile agents. The conflict resolution problem is addressed considering realistic restrictions on possible maneuvers. We formulate this problem as one in Mixed Integer Linear Programming (MILP). The method, which proves successful in a centralized implementation with a large number of cooperating agents, is also extended to a decentralized setting. Conditions for the existence of conflict avoidance maneuvers for a system of 5 autonomous agents with a transitive information structure are provided, along with the explicit policy to be applied by each agent.

}, keywords = {Embedded Control, Robotics}, author = {L. Pallottino and V. G. Scordio and A. Bicchi} } @conference {BMP04, title = {Discrete and Hybrid Nonholonomy}, booktitle = {Hybrid Systems: Computation and Control}, series = {LNCS}, volume = {2993}, number = {157{\textendash}172}, year = {2004}, pages = {157-172}, publisher = {Springer-Verlag}, organization = {Springer-Verlag}, abstract = {

In this paper we consider the generalization of the classical notion of nonholonomy of smooth constraints in analytical mechanics, to a substantially wider set of systems, allowing for discrete and hybrid (mixed continuous and discrete) configurations and transitions. We show that the general notion of nonholonomy can be captured by the definition of two different types of nonholonomicbehaviours, which we call {\em internal}nd {\em external}, respectively. Examples are reported of systems exhibiting either the former only, or the latter only, or both. For some classes of systems, we provide equivalent or sufficient characterizations of such definitions, which allow for practical tests.

}, keywords = {Embedded Control, Robotics}, author = {A. Bicchi and A. Marigo and B. Piccoli}, editor = {R. Alur and G. Pappas} } @article {MFB03, title = {A Hybrid-Control Approach to the Parking Problem of a Wheeled Vehicle Using Limited View-Angle Visual Feedback}, journal = {Int. Jour. of Robotics Research}, volume = {23}, number = {4-5}, year = {2004}, month = {April-May}, pages = {437-448}, abstract = {

In this paper we consider the mobile robot parking problem, i.e. the stabilization of a wheeled vehicle to a given position and orientation, using only visual feedback from low-cost cameras. The practically most relevant problem of keeping the tracked features in sight of the camera while maneuvering to park the vehicle is taken into account. This constraint, often neglected in the literature, combines with the nonholonomic nature of the vehicle kinematics in a challenging controller design problem. We provide an effective solution to such problem by using a combination of previous results on non-smooth control synthesis and recently developed hybrid control techniques. Simulations and experimental results on a laboratory vehicle are reported, showing the practicality of the proposed approach.

}, keywords = {Embedded Control, Robotics}, author = {P. Murrieri and D. Fontanelli and A. Bicchi} } @conference {PPSB04, title = {Motion Planning through Symbols and Lattices}, booktitle = {Proc. IEEE Int. Conf. on Robotics and Automation}, year = {2004}, pages = {3914-3919}, abstract = {

In this paper we propose a new approach to motion planning, based on the introduction of a lattice structure in the workspace of the robot, leading to efficient computations of plans for rather complex vehicles, and allowing for the implementation of optimization procedures in a rather straightforward way. The basic idea is the purposeful restriction of the set of possible inputfunctions to the vehicle to a finite set of symbols, or {\em control quanta},which, under suitable conditions, generate a regular lattice of reachable points. Once the lattice is generated and a convenient description computed, standard techniques in integer linear programming can be used to find a plan very efficiently. We also provide a correct and complete algorithm to the problem of finding an optimized plan (with respect e.g. to length minimization) consisting in a sequence of graph searches.

}, keywords = {Embedded Control, Robotics}, author = {S. Pancanti and L. Pallottino and D. Salvadorini and A. Bicchi} } @inbook {BLMS03, title = {On The Problem of Simultaneous Localization, Map Building, and Servoing of Autonomous Vehicles}, booktitle = {Advances in Control of Articulated and Mobile Robots}, series = {STAR - Springer Tracts in Advanced Robotics}, number = {10}, year = {2004}, pages = {223-239}, publisher = {Springer Verlag}, organization = {Springer Verlag}, abstract = {

In this chapter, we consider three of the main problems that arise in the navigation of autonomous vehicles in partially or totally unknown environments, i.e. building a map of the environment, self-localizing, and servoing the robot so as to achieve given goals based on sensorial information. As compared to most part of the existing literature on SLAM, we privilege here a system-theoretic view to the problem, which allows the localization and mapping problems to be cast in a unified framework with the control problem. The chapter is an overview of existing results in this vein, and of some interesting directions for research in the field. All chapters of this volume were revised and published online March 2005. The volume number was corrected from 4010 to 10.

}, keywords = {Embedded Control, Robotics}, author = {A. Bicchi and F. Lorussi and P. Murrieri and V. G. Scordio}, editor = {B. Siciliano and A. De Luca and C. Melchiorri and G. Casalino} } @conference {BJPP, title = {Quantised Control in Distributed Embedded Systems.}, booktitle = {Proc. 16th Int. Symp. on Mathematical Theory of Networks and Systems}, year = {2004}, abstract = {

Traditional control design is based on ideal assumptions concerning the amount, type and accuracy of the information flow that can be circulated across the controller. Unfortunately, real implementation platforms exhibit non-idealities that may substantially invalidate such assumptions. As a result, the system’s closed-loop performance can be severely affected and sometimes stability itself is jeopardised. These problems show up with particular strength when multiple feedback loops share a limited pool of computation and communication resources. In this case the designer is confronted with the challenging task of choosing at the same time the control law and the optimal allocation policy for the shared resources (control algortihm/system architecture co-design).

}, keywords = {Embedded Control, Robotics}, author = {A. Bicchi and K. H. Johansson and L. Palopoli and B. Picasso} } @article {MCB04, title = {Reachability and Steering of Rolling Polyhedra: A Case Study in Discrete Nonholonomy}, journal = {IEEE Trans. on Automatic Control}, volume = {49}, number = {5}, year = {2004}, month = {May}, pages = {710-726}, abstract = {

Rolling a ball on a plane is a standard example of nonholonomy reported in many textbooks, and the problem is also well understood for any smooth deformation of the surfaces. For non-smoothly deformed surfaces, however, much less is known. Although it may seem intuitive that nonholonomy is conserved (think e.g. to polyhedral approximations of smooth surfaces), current definitions of {\textquoteleft}{\textquoteleft}nonholonomy{\textquoteright}{\textquoteright} are inherently referred to systems described by ordinary differential equations, and are thus inapplicable to such systems. \{\.I}n this paper we study the set of positions and orientations that a polyhedral part can reach by rolling on a plane through sequences of adjacent faces. We provide a description of such reachable set, discuss conditions under which the set is dense, or discrete, or has a compound structure, and provide a method for steering the system to a desired reachable configuration, robustly with respect to model uncertainties. \\Based on ideas and concepts encountered in this case study, and in some other examples we provide, we turn back to the most general aspects of the problem and investigate the possible generalization of the notion of (kinematic) nonholonomy to non-smooth, discrete, and hybrid dynamical systems. To capture the essence of phenomena commonly regarded as {\textquoteleft}{\textquoteleft}nonholonomic{\textquoteright}{\textquoteright}, at least two irreducible concepts are to be defined, of {\textquoteleft}{\textquoteleft}internal{\textquoteright}{\textquoteright} and {\textquoteleft}{\textquoteleft}external{\textquoteright}{\textquoteright} nonholonomy, which may coexist in the same system. These definitions are instantiated by examples.

}, keywords = {Embedded Control, Robotics}, author = {A. Bicchi and Y. Chitour and A. Marigo} } @conference {PB04mi, title = {Some relations between ergodicity and minimality properties of invariant sets in quantized control systems}, booktitle = {Bifurcations in nonsmooth and hybrid dynamical systems: analysis, control and applications}, series = {S.I.C.C. (Societ\à Italiana Caos e Complessit\à)}, year = {2004}, note = {

poster presentation

}, month = {21-22 October}, address = {Milan}, abstract = {

Linear dynamical systems controlled by quantized inputs exhibit phenomena which are typically non-linear, including chaotic behaviours. We consider discrete-time single-input models of the type x(k+1)=Ax(k)+bu(k). The construction of invariant sets for this class of hybrid systems is of utmost importance for the stabilization problem. We first review a technique to construct invariant sets when an arbitrary quantized input set is assigned. We hence study minimality properties for invariant sets when inputs take integer values. There is a relation between a so-called strong minimality property and ergodicity of the closed-loop dynamics, in particular, ergodicity implies strong minimality. A condition ensuring strong minimality is given in terms of the coefficients of the characteristic polynomial of the matrix {\textquoteright}A{\textquoteright}. Two examples are presented: the first one shows that strong minimality does not imply ergodicity. The second one shows that our condition for strong minimality is only sufficient: this is done by exhibition of an ergodic dynamics for which our condition is not satisfied.

}, keywords = {Embedded Control, Robotics}, author = {B. Picasso and A. Bicchi} } @conference {DFB04, title = {Towards Cooperative Visual-Based Localization, Mapping, and Servoing}, year = {2004}, note = {

Proc. IEEE Mediterranean Conf.

}, abstract = {

In this paper we consider the problem of navigating an autonomous robot using primarily vision for localizing the robot, building a map of the environment, and navigating through viapoints to goals. A visual servo scheme is used that can steer the wheeled vehicle among images. Goal images do not necessarily correspond to images physically taken from the desired vehicle posture, as servoing to reconstructed virtual images is possible. A topological image map is constructed to support this, based on images grabbed by on-board cameras, along with a global feature-based metric map, using extended Kalman filter techniques. The method also enables a team of multiple vehicles to merge their information, and to coordinate navigation using each other{\textquoteright}s images. Realistic assumptions on limited communication bandwidth between agents and available memory storage are taken into account considering informative, memory-safe maps. Simulations and preliminary experimental results on a laboratory setup are reported.

}, keywords = {Embedded Control, Robics}, author = {A. Danesi and D. Fontanelli and A. Bicchi} } @conference {DFMSB03, title = {Cooperative Simultaneous Localization and Map Building for Servoing}, booktitle = {Proceedings of Multiagent Robotic Systems Trends and Industrial Application - Robocup 2003 Conference}, year = {2003}, month = {July}, address = {Padova}, keywords = {Embedded Control, Robotics}, author = {A. Danesi and D. Fontanelli and P. Murrieri and V. G. Scordio and A. Bicchi} } @conference {BMP03, title = {Encoding steering control with symbols}, booktitle = {Proc. IEEE Int. Conf. on Decision and Control}, year = {2003}, pages = {3343-3348}, abstract = {

In this paper, we consider the problem of steering complex dynamical systems among equilibria in their state space in efficient ways. Efficiency is considered as the possibility of compactly representing the (typically very large, or infinite) set of reachable equilibria and quickly computing plans to move among them. To this purpose, we consider the possibility of building lattice structures by purposefully introducing quantization of inputs. We consider different ways in which control actions can be encoded in a finite or numerable set of symbols, review different applications where symbolic encoding of control actions can be employed with success, and provide a unified framework in which to study the many different possible manifestations of the idea.

}, keywords = {Embedded Control, Robotics}, author = {A. Bicchi and A. Marigo and B. Piccoli} } @conference {OVMB03, title = {From nominal to robust planning: The plate-ball manipulation system}, booktitle = {Proc. IEEE Int. Conf. on Robotics and Automation}, year = {2003}, month = {May}, pages = {3175-3180}, address = {Taipei, Taiwan}, abstract = {

Robotic manipulation by rolling contacts is an appealing method for achieving dexterity with relatively simple hardware. While there exist techniques for planning motions of rigid bodies in rolling contact under nominal conditions, an inescapable challenge is the design of robust controllers of provable performance in the presence of model perturbations. As a preliminary step in this direction, we present in this paper an iterative robust planner of arbitrary accuracy for the plate-ball manipulation system subject to perturbations on the sphere radius. The basic tool is an exact geometric planner for the nominal system, whose repeated application guarantees the desired robustness property on the basis of the Iterative Steering paradigm. Simulation results under perturbed conditions show the effectiveness of the method.

}, keywords = {Embedded Control, Robotics}, author = {G. Oriolo and M. Vendittelli and A. Marigo and A. Bicchi} } @article {BB02, title = {Necessary and Sufficient Conditions for Robust Perfect Tracking under Variable Structure Control}, journal = {International Journal of Robust and Nonlinear Control}, volume = {13}, number = {2}, year = {2003}, month = {02/2003}, pages = {141-151}, abstract = {

The tracking control of linear MIMO systems with structured uncertainty is considered. A necessary and sufficient condition for robust asymptotic tracking employing variable structure techniques in the presence of multiplicative uncertainty is derived. The constructive proof of the theorem provides an explicit formula for controller synthesis.

}, keywords = {Embedded Control, Robotics}, author = {A. Balluchi and A. Bicchi} } @conference {PCB03, title = {Quality of service control in soft real-time applications}, booktitle = {Proc. IEEE Int. Conf. on Decision and Control}, year = {2003}, pages = {664-669}, abstract = {

In this paper we present results obtained in the context of Quality of Service (QoS) control for soft real-time applications. The discussion addresses the issue of dynamically adjusting the bandwidth for a set of periodic tasks, when a reservation-based (RB) CPU scheduling policy is used. RB techniques are particularly suitable for this kind of applications since they allow an accurate mathematical modelling of the dynamic evolution of the QoS experienced by tasks. Based on this model, a control policy guaranteeing specified QoS levels for different tasks is illustrated, along with necessary and sufficient conditions for its existence. Moreover, the problem of steering a task QoS back into its nominal level is tackled, in response to deviations due to temporary overload conditions. Simulation results are reported, for the purpose of validating the approach.

}, keywords = {Embedded Control, Robotics}, author = {L. Palopoli and T. Cucinotta and A. Bicchi} } @inbook {PB03-ADHS, title = {Receding-Horizon Control of LTI Systems with Quantized Inputs}, booktitle = {Analysis and Design of Hybrid Systems 2003}, year = {2003}, pages = {259-264}, publisher = {Elsevier}, organization = {Elsevier}, abstract = {

This paper deals with the stabilization problem for a particular class of hybrid systems, namely discrete-time linear systems subject to a uniform (a priori fixed) quantization of the control set. Results of our previous work on the subject provided a description of minimal (in a specific sense) invariant sets that could be rendered maximally attractive under any quantized feedback strategy. In this paper, we consider the design of stabilizing laws that optimize a given cost index on the state and input evolution on a finite, receding horizon. Application of Model Predictive Control techniques for the solution of similar hybrid control problems through Mixed Logical Dynamical reformulations can provide a stabilizing control law, provided that the feasibility hypotheses are met. In this paper, we discuss precisely what are the shortest horizon length and the minimal invariant terminal set for which it can be guaranteed a stabilizing MPC scheme. The final paper will provide an example and simulations of the application of the control scheme to a practical quantized control problem.

}, keywords = {Embedded Control, Robotics}, author = {B. Picasso and S. Pancanti and A. Bemporad and A. Bicchi}, editor = {Gueguen Engell and Zaytoon} } @conference {ZBSVB03, title = {Stabilization of a class of discrete-time hybrid automata}, booktitle = {Proc. IEEE Int. Conf. on Decision and Control}, year = {2003}, pages = {1147-1152}, abstract = {

In this paper, the problem of stabilizing linear discrete time hybrid automata is considered. A synthesis methodology is obtained by extending to hybrid systems the stabilization techniques based on stable convex combinations, originally developed for switching systems. An algorithm to explore the candidate stabilizing controller actions is proposed and an application to an automotive engine control problem is described.

}, keywords = {Embedded Control, Robotics}, author = {M. Zoncu and A. Balluchi and A. Sangiovanni Vincentelli and A. Bicchi} } @inbook {PB03-HSCC, title = {Stabilization of LTI Systems with Quantized State-Quantized Input Static Feedback}, booktitle = {Hybrid Systems: Computation and Control}, series = {Lecture Notes in Computer Science}, volume = {LNCS 2623}, year = {2003}, pages = {405-416}, publisher = {Springer-Verlag}, organization = {Springer-Verlag}, address = {Heidelberg, Germany}, abstract = {

This paper is concerned with the stabilization problem for discrete-time linear systems subject to a uniform quantization of the control set and to a regular state quantization, both fixed a priori. As it is well known, for quantized systems only weak (practical) stability properties can be achieved. Therefore, we focus on the existence and construction of quantized controllers (mapping a quantized state into a quantized input set) capable of steering a system to within invariant neighbourhoods of the equilibrium. Such analysis is helpful because it allows to decide a priori whether adesired control objective can be achieved by using a \textit{given} technology (actuators, sensors, communication and computational means).

}, keywords = {Embedded Control, Robotics}, author = {B. Picasso and A. Bicchi}, editor = {A. Pnueli and O. Maler} } @article {PFB02-TITS, title = {Conflict Resolution Problems for Air Traffic Management Systems Solved with Mixed Integer Programming}, journal = {IEEE Trans. Intelligent Transportation Systems}, volume = {3}, number = {1}, year = {2002}, month = {March}, pages = {3-11}, abstract = {

This paper considers the problem of solving conflicts arising among several aircraft that are assumed to move in a shared airspace. Aircraft can not get closer to each other than a given safety distance in order to avoid possible conflicts between different airplanes. For such system of multiple aircraft, we consider the path planning problem among given waypoints avoiding all possible conflicts. In particular we are interested in optimal paths, i.e. we want to minimize the total flight time. We propose two different formulations of the multi-aircraft conflict avoidance problem as a mixed-integer linear program: in the first case only velocity changes are admissible maneuvers, in the second one only heading angle changes are allowed. Due to the linear formulation of the two problems, solutions may be obtained quickly with standard optimization software, allowing our approach to be implemented in real time.

}, keywords = {Embedded Control, Robotics}, author = {L. Pallottino and E. Feron and A. Bicchi} } @conference {PGB02, title = {Construction of invariant and attractive sets for quantized-input linear systems}, booktitle = {Proc. IEEE Int. Conf. on Decision and Control}, year = {2002}, month = {December}, pages = {824-829}, abstract = {

In this paper, the problem of the stabilization of a discrete-time linear system subject to a fixed and uniformly quantized control set is considered. It is well known that, working with quantized inputs, the states of the system (except for a negligible set of initial conditions) cannot reach asymptotically the equilibrium point. Our aim is then to find an invariant and attractive neighborhood of the equilibrium and provide with a controller which steers the system into it. We construct a continuous and increasing family of invariant sets including one which is, in a specific sense, minimal. The invariance and attractivity properties of such sets are revised in the finite control set case: we propose a family of controllers taking on a finite number of values and ensuring the system convergence to the minimal invariant set. Some consequences of our technique are underlined with particular regard to the usage of Model Predictive Control tools. In the last section an example which shows the effectiveness of our results is presented.

}, keywords = {Embedded Control, Robotics}, author = {B. Picasso and F. Gouaisbaut and A. Bicchi} } @conference {MFBENEA02, title = {Controllo Ibrido di Veicoli su Ruote con Retroazione Visiva}, booktitle = {Proc. 1st. Natl. Conf. and Exhibit on Autonomous Intelligent Systems and Advanced Robotics}, year = {2002}, month = {October}, pages = {197-199}, address = {ENEA, Frascati}, keywords = {Embedded Control, Robotics}, author = {P. Murrieri and D. Fontanelli and A. Bicchi} } @conference {MPB02, title = {A Group-Theoretic Characterization of Quantized Control Systems}, booktitle = {Proc. IEEE Int. Conf. on Decision and Control}, year = {2002}, month = {December}, pages = {811-816}, abstract = {

In this paper we consider the reachability problem for quantized control systems, i.e. systems that take inputs from a finite set of symbols. Previous work addressed this problem for linear systems and for some specific classes of nonlinear driftless systems. In this paper we attack the study of more general nonlinear systems. To do so we find it useful to pose the problem in more abstract terms, and make use of the wealth of tools available in group theory, which enables us to proceed in our agenda of better understanding effects of quantization of inputs on dynamic systems.

}, keywords = {Embedded Control, Robotics}, author = {A. Marigo and B. Piccoli and A. Bicchi} } @conference {MB02-ICRA, title = {A local-local planning algorithm for rolling objects}, booktitle = {Proc. IEEE Int. Conf. on Robotics and Automation}, year = {2002}, month = {May}, pages = {1759-1764}, abstract = {

In this paper, we consider planning motions of objects of regular shape rolling on a plane among obstacles. Theoretical foundations and applications of this type of operations in robotic manipulation and locomotion have been discussed elsewhere. In this paper, we propose a novel algorithm that improves upon existing techniques in that: i) it is finitely computable and predictable (an upper bound on the computations necessary to reach a given goal within a tolerance can be given), and ii) it possesses a topological (local-local) property which enables obstacles and workspace limitations to be dealt with in an effective way.

}, keywords = {Embedded Control, Robotics}, author = {A. Marigo and A. Bicchi} } @conference {PBSV02, title = {Numerically efficient control of systems with communication constraints}, booktitle = {Proc. IEEE Int. Conf. on Decision and Control}, year = {2002}, month = {December}, pages = {1626-1631}, abstract = {

The problem of stabilization to the trivial equilibrium of a system with communication constraints is addressed. The communication constraints are related to the fact that commands are issued to different groups of actuators through a shared resource. We tackle the problem by using a Model Predictive Control scheme, which,at every step, decides the allocation of the bus {\em and} he control command values. After discussing two different alternatives for dealing with the scheduling constraints, we develop a formulation based on the generalized linear complementarity problem, which enables the application of efficient numerical solutions. Finally, we give some preliminary result on the parametric dependence of the problem{\textquoteright}s solution from the system{\textquoteright}s state.

}, keywords = {Embedded Control, Robotics}, author = {L. Palopoli and A. Bicchi and A. L. Sangiovanni-Vincentelli} } @inbook {PLPB02, title = {Optimal control of quantized input systems}, booktitle = {Hybrid Systems: Computation and Control}, series = {Lecture Notes in Computer Science}, volume = {LNCS 2289}, year = {2002}, pages = {351-363}, publisher = {Springer-Verlag}, organization = {Springer-Verlag}, address = {Heidelberg, Germany}, abstract = {

In this paper we consider the problem of optimal control (specifically, minimum-time steering) for systems with quantized inputs. In particular, we propose a new approach to the solution of the optimal control problem for an important class of nonlinear systems, i.e. chained-form systems. By exploiting results on the structure of the reachability set of these systems under quantized control, the optimal solution is determined solving an integer linear programming problem. Our algorithm represents an improvement with respect to classical approaches in terms of exactness, as it does not resort to any a priori state-space discretization. Although the computational complexity of the problem in our formulation is still formally exponential, it lends itself to application of Branch and Bound techniques, which substantially cuts down computations in many cases, as it has been experimentally observed.

}, keywords = {Embedded Control, Robotics}, author = {S. Pancanti and L. Leonardi and L. Pallottino and A. Bicchi}, editor = {C. Tomlin and M. Greenstreet} } @conference {PPB02, title = {On Optimal Steering of Quantized Input Systems}, booktitle = {Proceedings of the NSF/ONR Workshop on Future Directions in Nonlinear Control of Mechanical Systems}, year = {2002}, address = {Urbana, IL.}, abstract = {

In this paper we consider the problem of optimal control (specifically, minimum-time steering) for systems with quantized inputs. In particular, we propose a new approach to the solution of the optimal control problem for an important class of nonlinear systems, i.e. chained-form systems. By exploiting results on the structure of the reachability set of these systems under quantized control, the optimal solution is determined solving an integer linear programming problem. Our algorithm represents an improvement with respect to classical approaches in terms of exactness, as it does not resort to any a priori state-space discretization. Although the computational complexity of the problem in our formulation is still formally exponential, it lends itself to application of Branch and Bound techniques, which substantially cuts down computations in many cases, as it has been experimentally observed.

}, keywords = {Embedded Control, Robotics}, author = {S. Pancanti and L. Pallottino and A. Bicchi} } @article {BMP02, title = {On the reachability of quantized control systems}, journal = {IEEE Trans. on Automatic Control}, volume = {4}, number = {47}, year = {2002}, month = {April}, pages = {546-563}, abstract = {

In this paper we study control systems whose input sets are quantized, i.e. finite or regularly distributed on a mesh. We specifically focus on problems relating to the structure of the reachable set of such systems, which may turn out to be either dense or discrete. We report results on the reachable set of linear quantized systems, and on a particular but interesting class of nonlinear systems, i.e. nonholonomic chained-form systems. For such systems, we provide a complete characterization of the reachable set, and, in the case the set is discrete, a computable method to completely and succinctly describe its structure. Implications and open problems in the analysis and synthesis of quantized control systems are addressed.

}, keywords = {Embedded Control, Robotics}, author = {A. Bicchi and A. Marigo and B. Piccoli} } @conference {PBENEA02, title = {Risoluzione ottima dei conflitti tra agenti autonomi: applicazione al controllo del traffico aereo}, booktitle = {Proc. 1st. Natl. Conf. and Exhibit on Autonomous Intelligent Systems and Advanced Robotics}, year = {2002}, month = {October}, pages = {193-197}, address = {ENEA, Frascati}, keywords = {Embedded Control, Robotics}, author = {L. Pallottino and A. Bicchi} } @conference {PBP02, title = {Safety of a decentralized scheme for Free-Flight ATMS using Mixed Integer Linear Programming}, booktitle = {American Control Conference}, year = {2002}, month = {May}, pages = {742-747}, abstract = {

In this paper we consider policies for free-flight management of air traffic. We consider instantaneous and bounded heading angle deviation as conflict avoidance maneuvers. The corresponding model, resulting in a Mixed Integer Linear Programming (MILP) problem allow to solve both conflict detection and conflict resolution problems. The developed algorithm proved successful in a centralized implementation with a large number of cooperating aircraft. However, the application of such algorithm to a Free Flight environment, where cooperation can only be expected from neighboring aircraft, poses many challenges. We consider a model of the decentralized conflict resolution strategy that is based on a hybrid system, and sufficient conditions under which a 3-aircraft Free Flight MILP-based scheme guarantees safety of flight are provided.

}, keywords = {Embedded Control, Robotics}, author = {L. Pallottino and A. Bicchi and S. Pancanti} } @inbook {PPSEB02, title = {Synthesis of robust control systems under resource constraints}, booktitle = {Hybrid Systems: Computation and Control}, series = {Lecture Notes in Computer Science}, volume = {LNCS 2289}, year = {2002}, pages = {337-350}, publisher = {Springer-Verlag}, organization = {Springer-Verlag}, address = {Heidelberg, Germany}, keywords = {Embedded Control, Robotics}, author = {L. Palopoli and C. Pinello and A. L. Sangiovanni-Vincentelli and L. El-Ghaoui and A. Bicchi}, editor = {M. Greenstreet and C. Tomlin} } @inbook {MFB02, title = {Visual-servoed parking with limited view angle}, booktitle = {Experimental Robotics VIII}, series = {Springer Tracts in Advanced Robotics (STAR)}, volume = {5}, year = {2002}, pages = {254-263}, publisher = {Springer Verlag}, organization = {Springer Verlag}, abstract = {

In this paper the problem of stabilizing a wheeled vehicle of unicycle type to a set point, using only visual feedback, is considered. The practically most relevant problem of keeping the tracked features in sight of the camera while maneuvering to park the vehicle is taken into account. This constraint, often neglected in the literature, combines with the nonholonomic nature of the vehicle kinematics in a challenging controller design problem. We provide an effective solution to such problem by using a combination of previous results on non-smooth control synthesis, and recently developed hybrid control techniques. Simulations and experimental results on a laboratory vehicle are reported, showing the practicality of the proposed approach.

}, keywords = {Embedded Control, Robotics}, author = {P. Murrieri and D. Fontanelli and A. Bicchi}, editor = {B. Siciliano and P. Dario} } @conference {PPB00, title = {Shortest paths for teams of vehicles}, booktitle = {Proc. WAC Int. Symp. on Robotics and Applications}, year = {2000}, month = {June}, pages = {124-129}, abstract = {

In this paper we consider the problem of planning motions of a team of vehicles that move in a planar environment. Each vehicle is modelled as a kinematic system with velocity constraints and curvature bounds. Vehicles can not get closer to each other than a predefined safety distance. When manipulating a common object cooperatively, further constraints apply. For such systems, we consider the problem of planning optimal paths in the absence of obstacles.

}, keywords = {Embedded Control, Robotics}, author = {L. Pallottino and G. Parlangeli and A. Bicchi} } @inbook {B99, title = {An experimental study of performance and fault tolerance of a hybrid free-flight control scheme}, booktitle = {Robustness in Identification and Control}, series = {LNCIS 245}, year = {1999}, pages = {449-463}, publisher = {Springer Verlag}, organization = {Springer Verlag}, address = {Berlin Heidelberg, Germany}, keywords = {Embedded Control, Robotics}, author = {A. Bicchi}, editor = {A. Garulli and A. Tesi and A. Vicino} } @conference {PMBV98, title = {Active Suspensions Decoupling by Algebraic Output Feedback}, booktitle = {Proc. IEEE Mediterranean Conf. On Control And Systems}, year = {1998}, keywords = {Embedded Control, Robotics}, author = {D Prattichizzo and P. Mercorelli and A. Bicchi and A. Vicino} } @inbook {CMPB97, title = {Rolling Polyhedra on a Plane: Analysis of the Reachable Set}, booktitle = {Algorithms for Robotic Motion and Manipulation}, year = {1997}, pages = {277-286}, publisher = {A. K. Peters}, organization = {A. K. Peters}, address = {Wellesley, MA, U.S.A.}, keywords = {Embedded Control, Robotics}, author = {Y. Chitour and A. Marigo and D Prattichizzo and A. Bicchi}, editor = {J.P. Laumond and M. Overmars} } @conference {BBBC96, title = {Path Tracking Control for Dubin{\textquoteright}s Cars}, booktitle = {Proc. IEEE Int. Conf. on Robotics and Automation}, year = {1996}, keywords = {Autonomous Vehicles, Embedded Control, Nonlinear Control Systems}, author = {A. Balluchi and A. Bicchi and A. Balestrino and G. Casalino} } @conference {BBB95, title = {Quasi-Block Diagonal Dominance Condition for Robust Decentralized Tracking Control}, booktitle = {Proc. European Control Conference}, year = {1995}, address = {Rome}, keywords = {Embedded Control, Nonlinear Control Systems}, author = {A. Balluchi and A. Bicchi and A. Balestrino} } @conference {PBC93, title = {Statically Stable Legged Locomotion with Leg Redundancy}, booktitle = {Proc. IASTED Int. Conf. on Robotics and Manufacturing}, year = {1993}, publisher = {IASTED}, organization = {IASTED}, address = {Oxford, UK, september 23-25 1993}, keywords = {Embedded Control, Robotics}, issn = {O-88986-179-X}, author = {D Prattichizzo and A. Bicchi and G. Casalino} } @conference {BBL92, title = {Trajectory Planning of Industrial Robots in a Structured Environment}, booktitle = {Int. Conf. on CAD/CAM, Robotics and Factories of the Future}, year = {1992}, address = {Metz, France}, keywords = {Embedded Control, Robotics}, author = {A. Balestrino and A. Bicchi and A. Landi} } @conference {BBDGMP89, title = {Leg-Ankle-Foot System for Investigating Sensor Based Legged Locomotion}, booktitle = {Proc. IEEE/RSJ Int. Conf. on Intelligent Robots and Systems}, year = {1989}, address = {Tsukuba, Japan}, keywords = {Embedded Control, Robotics}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=637970}, author = {A. Bicchi and L. Bosio and P. Dario and M. Guiggiani and E. Manfredi and P. C. Pinotti} }