### Show only items where

#### Innovative technologies in underwater archaeology: field experience, open problems, research lines

 Title Innovative technologies in underwater archaeology: field experience, open problems, research lines Publication Type Journal Article Year of Publication 2006 Authors Caiti, A, Casalino, G, Conte, G, Zanoli, SM Journal CHEMISTRY IN ECOLOGY Pagination S383–S396 ISSN 0275-7540 Keywords Robotics URL http://dx.medra.org/10.1080/02757540600572321 DOI 10.1080/02757540600572321

#### GIS tools application for risk assessment of toxic waste buried in seafloor sediments

 Title GIS tools application for risk assessment of toxic waste buried in seafloor sediments Publication Type Journal Article Year of Publication 2006 Authors Caiti, A, Minciardi, R, Palmese, M, Robba, M, Sacile, R, Trucco, A Journal CHEMISTRY IN ECOLOGY Pagination S145–S161 ISSN 0275-7540 Keywords Robotics URL http://dx.medra.org/10.1080/02757540600670828 DOI 10.1080/02757540600670828

#### Efficient Numerical Approximation of Maximum Entropy Estimates

 Title Efficient Numerical Approximation of Maximum Entropy Estimates Publication Type Journal Article Year of Publication 2006 Authors Balestrino, A, Caiti, A, Crisostomi, E Journal INTERNATIONAL JOURNAL OF CONTROL Volume 79 Pagination 1145–1155 ISSN 0020-7179 Keywords Robotics URL http://dx.medra.org/10.1080/00207170600818373 DOI 10.1080/00207170600818373

#### Sensore di flusso tattile e di parametri ambientali

 Title Sensore di flusso tattile e di parametri ambientali Publication Type Patent Year of Publication 2006 Authors Vozzi, G, Cisternino, A, Colombo, D, Mazzei, D, Migliore, A Patent Number PI2006A000119 Keywords Bioengineering

#### Any Time Control

 Title Any Time Control Publication Type Miscellaneous Year of Publication 2006 Authors Fontanelli, D, Greco, L Keywords Embedded Control, Robotics 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–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–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.

#### On the Design and Control of Wireless Networked Embedded Systems

 Title On the Design and Control of Wireless Networked Embedded Systems Publication Type Conference Paper Year of Publication 2006 Conference Name Int. Conf. on Computer Aided Control System Design - CACSD'06 Pagination 440-445 Publication Language eng Authors Arzén, K-E, Bicchi, A, Hailes, S, Johansson, KH, Lygeros, J Publisher IEEE Keywords Embedded Control, Robotics 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.

#### A Compatible Electrocutaneous Display for functional Magnetic Resonance Imaging application

 Title A Compatible Electrocutaneous Display for functional Magnetic Resonance Imaging application Publication Type Conference Paper Year of Publication 2006 Conference Name Proc. 28th IEEE Engineering in Medicine and Biology Conference Pagination 100-102 Publication Language eng Authors Hartwig, V, Cappelli, C, Vanello, N, Ricciardi, E, Scilingo, EP, Giovannetti, G, Santarelli, MF, Positano, V, Landini, L, Bicchi, A Keywords Haptics Abstract In this paper we propose an MR (Magnetic Resonance) compatible electrocutaneous stimulator able to inject an electric current, variable in amplitude and frequency, into the fingertips in order to elicit tactile skin receptors (mechanoreceptors). The desired goal is to evoke specific tactile sensations selectively stimulating skin receptors by means of an electric current in place of mechanical stimuli. The field of application ranges from functional Magnetic Resonance Imaging (fMRI) tactile studies to augmented reality technology. The device here proposed is designed using safety criteria in order to comply with the threshold of voltage and current permitted by regulations. Moreover, MR safety and compatibility criteria were considered in order to perform experiments inside the MR scanner during an fMRI acquisition for functional brain activation analysis. Psychophysical laboratory tests are performed in order to define the different evoked tactile sensation. After verifying the device MR safety and compatibility on a phantom, a test on a human subject during fMRI acquisition is performed to visualize the brain areas activated by the simulated tactile sensation. Notes (poster presentation)

#### Safe and Dependable Physical Human-Robot Interaction in Anthropic Domains: State of the Art and Challenges

 Title Safe and Dependable Physical Human-Robot Interaction in Anthropic Domains: State of the Art and Challenges Publication Type Conference Paper Year of Publication 2006 Conference Name Proc. IROS'06 Workshop on pHRI - Physical Human-Robot Interaction in Anthropic Domains Publication Language eng Authors Alami, R, Albu-Schaeffer, A, Bicchi, A, Bischoff, R, Chatila, R, De Luca, A, De Santis, A, Giralt, G, Guiochet, J, Hirzinger, G, Ingrand, F, Lippiello, V, Mattone, R, Powell, D, Sen, S, Siciliano, B, Tonietti, G, Villani, L Editor Bicchi, A, De Luca, A Publisher IEEE Keywords Robotics

#### Adaptive output feedback control of spacecraft relative translation

 Title Adaptive output feedback control of spacecraft relative translation Publication Type Conference Paper Year of Publication 2006 Conference Name Proc. IEEE Int. Conf. on Decision and Control Date Published December Publication Language eng Authors Kristiansen, R, Lor, A, Chaillet, A, Nicklasson, PJ Conference Location San Diego, USA Keywords Robotics Abstract We address the problem of tracking relative translation in a leader-follower spacecraft formation using feedback from relative position only and under parameter uncertainty (spacecraft mass) and uncertainty in the leader variables (true anomaly rate and rate of change). We only assume boundedness of orbital perturbations and the leader control force but with unknown bounds. Under these conditions we propose a controller that renders the closed-loop system, uniformly semiglobally practically asymptotically stable. In particular, the domain of attraction can be made arbitrarily large by picking convenient gains, and the state errors in the closed-loop system are proved to converge from any initial condition within the domain of attraction to a ball in close vicinity of the origin in a stable way; moreover, this ball can be diminished arbitrarily by increasing the gains in the control law. Simulation results of a leader-follower spacecraft formation using the proposed controller are presented.

#### Hybrid Modelling and Control of the Common Rail Injection System

 Title Hybrid Modelling and Control of the Common Rail Injection System Publication Type Conference Paper Year of Publication 2006 Conference Name Hybrid Systems: Computation and Control Edited Volume 3927 / 2006 Pagination 79-92 Publication Language eng Authors Balluchi, A, Bicchi, A, Mazzi, E, Vincentelli, SA, Serra, G Editor Hespanha, J, Tiwari, A Publisher Springer-Verlag Keywords Embedded Control, Robotics 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.

#### Bi-modal Transducer-based Wearable System for Cardiac Monitoring

 Title Bi-modal Transducer-based Wearable System for Cardiac Monitoring Publication Type Conference Paper Year of Publication 2006 Conference Name Fourth IASTED International Conference on Biomedical Engineering Pagination 92-97 Date Published February Publication Language eng Authors Lanata, A, Scilingo, EP, Francesconi, R, De Rossi, D Conference Location Innsbruck, Austria Keywords Bioengineering

#### Improving efficiency of finite plans by optimal choice of input sets

 Title Improving efficiency of finite plans by optimal choice of input sets Publication Type Conference Paper Year of Publication 2006 Conference Name Hybrid Systems: Computation and Control Edited Volume 3927 / 2006 Pagination 108-122 Publication Language eng Authors Bicchi, A, Marigo, A, Piccoli, B Editor Hespanha, J, Tiwari, A Publisher Springer-Verlag Keywords Embedded Control, Robotics 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–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.

#### Decentralized and scalable conflict resolution strategy for multi-agents systems

 Title Decentralized and scalable conflict resolution strategy for multi-agents systems Publication Type Conference Paper Year of Publication 2006 Conference Name Int. Symp. on Mathematical Theory of Networks and Systems Publication Language eng Authors Pallottino, L, Scordio, VG, Frazzoli, E, Bicchi, A Keywords Embedded Control, Robotics 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.

#### Estim

 Title Estim Publication Type Conference Paper Year of Publication 2006 Conference Name CIFA 2006 Date Published June Publication Language eng Authors Chaillet, A Conference Location Bordeaux, France Abstract Pour les systèmes non-linéaires, il est connu que la propriété de stabilité asymptotique est conservée par la structure de cascade. Le pr Notes In French

#### Probabilistic verification of a decentralized policy for conflict resolution in multi-agent systems

 Title Probabilistic verification of a decentralized policy for conflict resolution in multi-agent systems Publication Type Conference Paper Year of Publication 2006 Conference Name Proc. IEEE Int. Conf. on Robotics and Automation Pagination 2448-2453 Publication Language eng Authors Pallottino, L, Scordio, VG, Frazzoli, E, Bicchi, A Keywords Embedded Control, Robotics 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. Notes Correct version

#### Integral Input to State Stability for cascaded systems

 Title Integral Input to State Stability for cascaded systems Publication Type Conference Paper Year of Publication 2006 Conference Name MTNS 2006 Date Published July Publication Language eng Authors Chaillet, A, Angeli, D Conference Location Kyoto, Japan Keywords Robotics Abstract The Integral Input to State Stability (iISS) property is studied is the context of nonlinear time-invariant systems in cascade. A sufficient condition is given, in terms of the storage function of each subsystem, to ensure that the cascade composed of an iISS system driven by a Globally Asymptotically Stable (GAS) one remains GAS. Some sufficient conditions for the preservation of the iISS property under a cascade interconnection are also presented.

#### Practical stabilization of LTI SISO systems under assigned Input and Output quantization

 Title Practical stabilization of LTI SISO systems under assigned Input and Output quantization Publication Type Conference Paper Year of Publication 2006 Pagination 353-358 Date Published July Publication Language eng Authors Picasso, B, Bicchi, A Keywords Embedded Control, Robotics Abstract This work is concerned with the practical stabilization of discrete–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. Notes ADHS'06

#### A converse Lyapunov theorem for semiglobal practical asymptotic stability and application to cascades-based control

 Title A converse Lyapunov theorem for semiglobal practical asymptotic stability and application to cascades-based control Publication Type Conference Paper Year of Publication 2006 Conference Name Proc. IEEE Int. Conf. on Decision and Control Date Published December Publication Language eng Authors Chaillet, A, Lor, A Conference Location San Diego, USA Keywords Robotics Abstract We present a converse Lyapunov result for nonlinear time-varying systems that are uniformly semiglobally asymptotically stable. This stability property pertains to the case when the size of initial conditions may be arbitrarily enlarged and the solutions of the system converge, in a stable way, to a closed ball that may be arbitrarily diminished by tuning a design parameter of the system (typically but not exclusively, a control gain). This result is notably useful in cascaded-based control when uniform practical asymptotic stability is established without a Lyapunov function, , ıt e.g.} via averaging. We provide a concrete example by solving the stabilization problem of a hovercraft.

#### Brain response to visual, tactile and auditory flow in sighted and blind individuals supports a supramodal functional organization in hMT complex

 Title Brain response to visual, tactile and auditory flow in sighted and blind individuals supports a supramodal functional organization in hMT complex Publication Type Conference Paper Year of Publication 2006 Conference Name Proc. 12th International Conference on Functional Mapping of Human Brain Mapping Edited Volume 31 Pagination 512 TH-P Publication Language eng Authors Ricciardi, E, Sani, L, Gentili, C, Bonino, D, Vanello, N, Haxby, JV, Seifritz, E, Guazzelli, M, Landini, L, Bicchi, A, Di Salle, F, Pietrini, P Publisher Elsevier Keywords Haptics Notes Florence

#### Uniform Global Practical Stability for non-autonomous cascaded systems

 Title Uniform Global Practical Stability for non-autonomous cascaded systems Publication Type Conference Paper Year of Publication 2006 Conference Name MTNS 2006 Date Published July Publication Language eng Authors Chaillet, A, Lor, A Conference Location Kyoto, Japan Keywords Robotics Abstract This paper aims to give sufficient conditions for a cascade composed of nonlinear time-varying systems that are uniformly globally practically asymptotically stable (UGPAS) to be UGPAS. These conditions are expressed as relations between the Lyapunov function of the driven subsystem and the interconnection term. Our results generalize previous theorems that establish the uniform global asymptotic stability of cascades.

#### Free Hand Haptic Interfaces Based on Magnetorheological Fluids

 Title Free Hand Haptic Interfaces Based on Magnetorheological Fluids Publication Type Conference Paper Year of Publication 2006 Conference Name Proc. 14th Symp. on Haptic Interfaces for Virtual Environment and Teleoperator Systems Pagination 367-371 Date Published March Publication Language eng Authors Sgambelluri, N, Rizzo, R, Scilingo, EP, Raugi, M, Bicchi, A Keywords Haptics Abstract This paper is concerned with exploring the possibility of using Magneto-Rheological Fluids (MRF) as haptic interface. MRF are special materials capable of changing their rheological behaviour with an external magnetic field. This property suggested us to use MRF to mimic virtual objects whose compliance can be gradually modulated. Several architectures of prototypes have been envisaged. The general scheme of both prototypes refers to a Haptic Black Box (HBB) concept, intended as a box where the operator can poke his/her bare hand, and interact with the virtual object by freely moving the hand without mechanical constraints. In this way sensory receptors on the whole operator Notes Poster presentation

#### Robustness of PID controlled manipulators with respect to external disturbances

 Title Robustness of PID controlled manipulators with respect to external disturbances Publication Type Conference Paper Year of Publication 2006 Conference Name Proc. IEEE Int. Conf. on Decision and Control Date Published December Publication Language eng Authors Chaillet, A, Lor, A, Kelly, R Conference Location San Diego, USA Keywords Robotics Abstract We present a robustness analysis for PID-controlled robot manipulators. For robot manipulators under the influence of external disturbances we provide a proof, and a tuning procedure, to establish uniform semiglobal practical asymptotic stability. In particular, in contrasts to other works on robust stability of PIDs, we do not use La Salle's principle but provide a strict Lyapunov function. The perturbations that we consider include discontinuous functions of the state, such as Coulomb friction. As corollaries of our main results, one may conclude the same stability property for the case of motion control using linear PID.

#### Advanced Modeling and preliminary psychophysical experiments for a free-hand haptic device

 Title Advanced Modeling and preliminary psychophysical experiments for a free-hand haptic device Publication Type Conference Paper Year of Publication 2006 Conference Name Proc. IEEE/RSJ Int. Conf. on Robots and Intelligent Systems - IROS06 Pagination 1558-1563 Date Published October Publication Language eng Authors Sgambelluri, N, Scilingo, EP, Bicchi, A, Rizzo, R, Raugi, M Keywords Haptics Abstract In this paper we report on a new improved free-hand haptic interface based on magnetorheological fluids (MRFs). MRFs are smart materials which change their rheology according to an external magnetic field. The new architecture here proposed results from the development and improvement of earlier prototypes. The innovative idea behind this device is to allow subjects interacting directly with an object, whose rheology is rapidly and easily changeable, freely moving their hands without rigid mechanical linkages. Numerical advanced simulation tests using algorithms based on finite element methods have been implemented, in order to analyze and predict the spatial distribution of the magnetic field. A special focus was laid on investigating on how the magnetic filed profile is altered by the introduction of the hand. Possible solutions were proposed to overcome this perturbation. Finally some preliminary psychophysical tests in order to assess the performance of the device are reported and discussed.

#### Stability of sets for nonlinear systems in cascade

 Title Stability of sets for nonlinear systems in cascade Publication Type Conference Paper Year of Publication 2006 Conference Name MTNS 2006 Date Published July Publication Language eng Authors Chaillet, A, Panteley, E Conference Location Kyoto, Japan Keywords Robotics Abstract The stability of (not necessarily compact) sets for nonlinear systems in cascade is addressed. It is proved that if two sets are globally asymptotically stable (GAS) for the subsystems taken separately then their cross-product is GAS for the corresponding cascade, provided that the solutions of the latter are globally bounded. In the case of a suitable growth rate of the interconnection in the state of the driven subsystem, we show that this latter requirement can be relaxed to just forward completeness of the cascade. Our results extend similar results on the stability analysis of cascaded systems and find applications in partial stability analysis and adaptive control.

#### Cascaded lemma for set-stable systems

 Title Cascaded lemma for set-stable systems Publication Type Conference Paper Year of Publication 2006 Conference Name Proc. IEEE Int. Conf. on Decision and Control Date Published December Publication Language eng Authors Tsonnas, J, Chaillet, A, Panteley, E, Johansen, TA Conference Location San Diego, USA Keywords Robotics Abstract A previous result about uniform global asymptotic stability (UGAS) of the equilibrium of a cascaded time-varying systems, is here also shown to hold for closed (not necessarily compact) sets composed by set-stable subsystems of a cascade. In view of this result an optimal control allocation approach is discussed.

#### A scalable platform for safe and secure decentralized traffic management of multiagent mobile systems

 Title A scalable platform for safe and secure decentralized traffic management of multiagent mobile systems Publication Type Conference Paper Year of Publication 2006 Conference Name ACM Workshop on Real-World Wireless Sensor Networks Publication Language eng Authors Danesi, A, Fagiolini, A, Savino, I, Pallottino, L, Schiavi, R, Dini, G, Bicchi, A Keywords Embedded Control, Robotics 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 neighboring'' agents. Ad-hoc wireless sensor networks are employed to provide support for this architecture.

#### Security and Advanced Control Issues in a Robotic Platform for Monitoring and Relief

 Title Security and Advanced Control Issues in a Robotic Platform for Monitoring and Relief Publication Type Conference Paper Year of Publication 2006 Conference Name Proc. of EWSN 2006 February 13-15, ETH Zurich Publication Language eng Authors Danesi, A, Savino, IM, Schiavi, R, Bicchi, A, Dini, G Keywords Embedded Control, Robotics Abstract This paper provides an architectural overview and a first implementation of an heterogeneous agent network composed by mobile robots of di

#### Symbolic Control for Underactuated Differentially Flat Systems

 Title Symbolic Control for Underactuated Differentially Flat Systems Publication Type Conference Paper Year of Publication 2006 Conference Name Proc. IEEE Int. Conf. on Robotics and Automation Pagination 1649-1654 Publication Language eng Authors Fagiolini, A, Greco, L, Bicchi, A, Piccoli, B, Marigo, A Keywords Embedded Control, Robotics 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.

#### Casting Robotic end-effectors to reach far objects in space and planetary missions

 Title Casting Robotic end-effectors to reach far objects in space and planetary missions Publication Type Conference Paper Year of Publication 2006 Conference Name Proc. of the 9th ESA Workshop on Advanced Space Technologies for Robotics and Automation Pagination 28-30 Publication Language eng Authors Fagiolini, A, Torelli, A, Bicchi, A Keywords Robotics

#### Adaptive non Linear Control of Dynamic Mobile Robots with Parameters Uncertainty

 Title Adaptive non Linear Control of Dynamic Mobile Robots with Parameters Uncertainty Publication Type Conference Paper Year of Publication 2006 Conference Name Int. IFAC Symp. on Robot Control Date Published September Publication Language eng Authors Fontanelli, D, Viviani, R, Greco, L, Caiti, A, Bicchi, A Conference Location Bologna, Italy Keywords Embedded Control, Robotics 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.

#### Active Mechatronic Interface for Haptic Perception Studies with Functional Magnetic Resonance Imaging: Compatibility and Design Criteria

 Title Active Mechatronic Interface for Haptic Perception Studies with Functional Magnetic Resonance Imaging: Compatibility and Design Criteria Publication Type Conference Paper Year of Publication 2006 Conference Name Proc. IEEE Int. Conf. on Robotics and Automation Pagination 3832-3837 Publication Language eng Authors Gassert, R, Vanello, N, Chapuis, D, Hartwig, V, Scilingo, EP, Bicchi, A, Landini, L, Burdet, E, Bleuler, H Keywords Haptics Abstract Functional brain exploration methodologies such as functional magnetic resonance imaging (fMRI), are critical tools to study perceptual and cognitive processes. In order to develop complex and well controlled fMRI paradigms, researchers are interested in using active interfaces with electrically powered actuators and sensors. Due to the particularity of the MR environment, safety and compatibility criteria have to be strictly followed in order to avoid risks to the subject under test, to the operators or to the environment, as well as to avoid artifacts in the images. This paper describes the design of an fMRI compatible mechatronic interface based on MR compatibility tests of materials and actuators. In particular, a new statistical test looks at the mean and variations of activity as a time series. The device with two degrees of freedom, allowing one translation with positionfeedback along a horizontal axis and one rotation about a vertical axis linked to the translation, was realized to investigate the brain mechanisms of dynamic tactile perception tasks. It can be used to move and orient various objects below the finger for controlled tactile stimulation. The MR compatibility of the complete interface is shown using the same statistical test as well as a functional study with a human subject.

#### Feedback Encoding for Efficient Symbolic Control of Dynamical Systems

 Title Feedback Encoding for Efficient Symbolic Control of Dynamical Systems Publication Type Journal Article Year of Publication 2006 Authors Bicchi, A, Marigo, A, Piccoli, B Journal IEEE Trans. on Automatic Control Volume 51 Pagination 1-16 Keywords Embedded Control, Robotics Abstract The problem of efficiently steering dynamical systems by generating finite input plans is considered. Finite plans are finite–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.

#### Necessary and sufficient conditions for uniform semiglobal practical asymptotic stability: Application to cascaded systems

 Title Necessary and sufficient conditions for uniform semiglobal practical asymptotic stability: Application to cascaded systems Publication Type Journal Article Year of Publication 2006 Authors Chaillet, A, Lor, A Journal Automatica Volume 42 Pagination 1899-1906 Date Published November Keywords Robotics Abstract It is well established that for a cascade of two uniformly globally asymptotically stable (UGAS) systems, the origin remains UGAS provided that the solutions of the cascade are uniformly globally bounded. While this result has met considerable popularity in specific applications it remains restrictive since, in practice, it is often the case that the decoupled subsystems are only uniformly \emph{semiglobally} \emph{practically} asymptotically stable (USPAS). Recently, we established that the cascade of USPAS systems is USPAS under a local boundedness assumption and the hypothesis that one knows a Lyapunov function for the driven subsystem. The contribution of this paper is twofold: 1) we establish USPAS of cascaded systems without the requirement of a Lyapunov function and 2) we present a converse theorem for USPAS. While other converse theorems in the literature cover the case of USPAS ours has the advantage of providing a bound on the gradient of the Lyapunov function, which is fundamental to establish theorems for cascades.

#### Uniform global practical asymptotic stability for non-autonomous cascaded systems

 Title Uniform global practical asymptotic stability for non-autonomous cascaded systems Publication Type Journal Article Year of Publication 2006 Authors Chaillet, A, Lor, A Journal European Journal of Control Volume 12 Keywords Robotics Abstract This paper aims to give sufficient conditions for a cascade composed of nonlinear time-varying systems that are uniformly globally practically asymptotically stable (UGPAS) to be UGPAS. These conditions are expressed as relations between the Lyapunov function of the driven subsystem and the interconnection term. Our results generalise previous theorems that establish the uniform global asymptotic stability of cascades.

#### A Geometry-Based Algorithm for the Stability of Planar Switching Systems

 Title A Geometry-Based Algorithm for the Stability of Planar Switching Systems Publication Type Journal Article Year of Publication 2006 Authors Greco, L, Tocchini, F, Innocenti, M Journal Int. J. of Systems Science Volume 37 Pagination 747–761 Keywords Embedded Control, Robotics
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