@conference {2082, title = {Design and preliminary affective characterization of a novel fabric-based tactile display}, booktitle = {Haptics Symposium (HAPTICS), 2014 IEEE}, year = {2014}, pages = { 591 - 596}, address = {Houston, TX}, keywords = {Haptics, Robotics}, doi = {10.1109/HAPTICS.2014.6775522}, author = {M. Bianchi and G. Valenza and A. Serio and A Lanata and L. Greco and M. Nardelli and E. P. Scilingo 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} } @article {GCB11, title = {Exploiting Packet Size in Uncertain Nonlinear Networked Control Systems}, journal = {Automatica}, volume = {48}, year = {2012}, pages = {2801 - 2811}, keywords = {Robotics}, author = {L. Greco and A. Chaillet 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 {FLGGMCFSB11, title = {Packet-based control}, booktitle = {Automatica.it 2011}, year = {2011}, note = {

poster presentation

}, month = {September, 7 - 9}, address = {Pisa, Italy}, keywords = {Robotics}, author = {S. Falasca and G. Lorefice and L. Greco and M. Gamba and S. Melani and A. Chaillet and D. Fontanelli and R. Schiavi and C Belsito} } @conference {GFP11, title = {Resource aware control}, booktitle = {Automatica.it 2011}, year = {2011}, month = {September}, address = {Pisa, Italy}, keywords = {Robotics}, author = {L. Greco and D. Fontanelli and L. Palopoli} } @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} } @booklet {GreTR10, title = {Sensor Deployment for Network-like Environments}, year = {2010}, note = {

Full version

}, keywords = {Robotics}, author = {L. Greco and M. Gaeta and B. Piccoli} } @article {GGP10, title = {Sensor Deployment for Network-like Environments}, journal = {IEEE Trans. on Automat. Contr.}, year = {2010}, note = {

Condit. accepted as Technical Note

}, keywords = {Robotics}, author = {L. Greco and M. Gaeta and B. Piccoli} } @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 {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 {GGP08, title = {Deployment of sensors in a network-like environment}, booktitle = {Proc. 47th IEEE Conference on Decision and Control}, year = {2008}, month = {December}, pages = {4257{\textendash}4262}, address = {Cancun, Mexico}, keywords = {Robotics}, doi = {10.1109/CDC.2008.4738862}, author = {L. Greco and M. Gaeta and B. Piccoli} } @conference {SBFGB08, title = {Optimal Paths in a Constrained Image Plane for Purely Image-Based Parking}, booktitle = {IROS}, year = {2008}, month = {22-26 Sept}, pages = {1673-1680}, abstract = {

This paper presents a correct solution to the optimal feedback control for a nonholonomic vehicle with limited field-of-view. Previous work on this subject has shown that the search for a shortest path can be limited to simple families of trajectories. We preliminarily provide an extension of the alphabet of optimal control words, to cover some regions of the vehicle plane where the synthesis of turns out to be suboptimal. The main contribution of this paper is an algorithm to translate the optimal synthesis to the image plane, thus enabling a purely image-based optimal control scheme. This allows better performance and increases the robustness of the overall process, avoiding the need of slowly-converging and error-prone parameter estimation algorithms. Simulations and experiments are reported which demonstrate the effectiveness of the proposed technique.

}, keywords = {Robotics}, author = {P Salaris and F. A. W. Belo and D. Fontanelli and L. Greco and A. Bicchi} } @conference {MED08-GFB, title = {Robust Almost Sure Stability for Uncertain Stochastically Scheduled Anytime Controllers}, booktitle = {Control and Automation, 16 th Mediterranean Conference on Control and Automation}, year = {2008}, pages = {249 - 254}, abstract = {

In this paper we consider closed loop stability of a number of different software tasks implementing a hierarchy of real-time controllers for a given plant, i.e.

}, keywords = {Robotics}, author = {D. Fontanelli and L. Greco 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} } @article {GreDCDIS06, title = {Comments on Necessary and Sufficient Vertex Solutions for Robust Stability Analysis of Families of Linear State Space Systems}, journal = {Dyn. Contin. Discrete Impuls. Syst. Ser. B Appl. Algorithms}, volume = {14}, number = {5}, year = {2007}, pages = {749{\textendash}752}, keywords = {Robotics}, author = {L. Greco} } @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} } @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} } @booklet {FontanelliG-TR06, title = {Any Time Control}, year = {2006}, month = {March}, publisher = {Interdepartmental Research Center E. Piaggio, University of Pisa}, address = {Pisa, Italy}, abstract = {

It is widely accepted in the control community that the Computer Controlled Systems (briefly, CCSs), have a lot of advantages based primarily on the high reconfigurability of the controller platform and the ability of making complex yet fast decisions. Such positive features make the CCS a useful platform for multitasking control, i.e. using only one single-processor platform to control several plants. Within this framework, the computer has to share its computational time to solve several critical tasks, each one with its priority. Taking into account schedulability and real time operating systems problems, it is just a step forward to realize that tasks with low priority could be interrupted any time, with unpredictable distributions, and it is just a logical intuition that not all the tasks can be at the highest priority. From a control point of view, each control task should compute a control input to the controlled system to prevent instability or to ensure the performances. This field seems to be at the border between the control community and the computer science community and it has not been widely investigated. Some work has been presented introducing more general scheduling models and methods for control systems, where control design methodology takes the availability of computing resources into account and allows the trade{\textendash}offs between control performance and computer resources utilization, and also introducing the idea of any time CCS without solutions. In literature, the Control Server is introduced, allowing the separation between scheduling and control design by treating the controllers as scalable real{\textendash}time components. Jitter and latency is included in the model and cannot be taken over. Furthermore, the interrupt time, the I/O operations and the overrun handling are not taken into account, simply imposing only soft real time control tasks. Useful tools for the analysis of real time control performance are the Jitterbug and the True Time that analyze the control performance once the control tasks are implemented as soft real time tasks.

}, keywords = {Embedded Control, Robotics}, author = {D. Fontanelli and L. Greco} } @article {GreIJSS06, title = {A Geometry-Based Algorithm for the Stability of Planar Switching Systems}, journal = {Int. J. of Systems Science}, volume = {37}, number = {11}, year = {2006}, pages = {747{\textendash}761}, keywords = {Embedded Control, Robotics}, author = {L. Greco and F. Tocchini and M. Innocenti} } @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} } @mastersthesis {GrecoPhD, title = {Stability and Stabilization Issues in Switched Systems}, year = {2005}, school = {University of Pisa}, type = {phd}, keywords = {Robotics}, author = {L. Greco} } @conference {TocCDC05, title = {Stabilization of a Class of Planar Nonlinear Systems}, booktitle = {44th IEEE CDC-ECC{\textquoteright}05}, year = {2005}, month = {December}, address = {Seville, Spain}, keywords = {Robotics}, author = {F. Tocchini and L. Greco and M. Innocenti} } @conference {GreMED04, title = {Stabilization of a Class of Unstable Switching Systems}, booktitle = {12th IEEE Mediterranean Conference}, year = {2004}, month = {June}, address = {Kusadasi, Turkey}, keywords = {Robotics}, author = {L. Greco and F. Tocchini and M. Innocenti} } @booklet {GreTR03, title = {Necessary and Sufficient Conditions for Asymptotic Stability of Second Order LTI Switching Systems}, year = {2003}, publisher = {Dept. of Electrical Systems and Automation, University of Pisa}, keywords = {Robotics}, author = {L. Greco and F. Tocchini and M. Innocenti} } @article {InnAut03, title = {Sliding Mode Control for Two-Time Scale Systems: Stability Issues}, journal = {Automatica}, volume = {39}, year = {2003}, month = {February}, pages = {273{\textendash}280}, keywords = {Robotics}, author = {M. Innocenti and L. Greco and L. Pollini} } @conference {InnACC02, title = {Stability Issues in Dual Time Scale Systems}, booktitle = {American Control Conference}, year = {2002}, month = {May}, address = {Anchorage, Alaska}, keywords = {Robotics}, author = {M. Innocenti and L. Greco and L. Pollini} } @booklet {GreTR02, title = {Variable Structure Control for Singularly Perturbed System: Stability Issues}, year = {2002}, month = {March}, publisher = {Dept. of Electrical Systems and Automation, University of Pisa}, address = {Pisa, Italy}, keywords = {Robotics}, author = {M. Innocenti and L. Greco} }