IMT Institutional Repository: No conditions. Results ordered -Date Deposited. 2021-12-03T22:17:56ZEPrintshttp://eprints.imtlucca.it/images/logowhite.pnghttp://eprints.imtlucca.it/2017-01-24T13:21:02Z2017-08-28T15:36:22Zhttp://eprints.imtlucca.it/id/eprint/3638This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/36382017-01-24T13:21:02ZOptimal energy management of a small-size building via hybrid model predictive controlAbstract This paper presents the design of a Model Predictive Control (MPC) scheme to optimally manage the thermal and electrical subsystems of a small-size building (“smart house”), with the objective of minimizing the expense for buying energy from the grid, while keeping the room temperature within given time-varying bounds. The system, for which an experimental prototype has been built, includes {PV} panels, solar collectors, a battery pack, an electrical heater in a thermal storage tank, and two pumps on the solar collector and radiator hydraulic circuits. The presence of binary control inputs together with continuous ones naturally leads to using a hybrid dynamical model, and the {MPC} controller solves a mixed-integer linear program at each sampling instant, relying on weather forecast data for ambient temperature and solar irradiance. The procedure for controller design is reported with focus on the specific application, and the proposed method is successfully tested on the experimental site.Albina KhakimovaAliya KusatayevaAkmaral ShamshimovaDana SharipovaAlberto Bemporadalberto.bemporad@imtlucca.itYakov FamiliantAlmas ShintemirovViktor TenMatteo Rubagotti2017-01-24T13:10:56Z2017-01-24T13:16:05Zhttp://eprints.imtlucca.it/id/eprint/3636This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/36362017-01-24T13:10:56ZA Lyapunov method for stability analysis of piecewise-affine systems over non-invariant domainsThis paper analyses stability of discrete-time piecewise-affine systems, defined on possibly non-invariant domains, taking into account the possible presence of multiple dynamics in each of the polytopic regions of the system. An algorithm based on linear programming is proposed, in order to prove exponential stability of the origin and to find a positively invariant estimate of its region of attraction. The results are based on the definition of a piecewise-affine Lyapunov function, which is in general discontinuous on the boundaries of the regions. The proposed method is proven to lead to feasible solutions in a broader range of cases as compared to a previously proposed approach. Two numerical examples are shown, among which a case where the proposed method is applied to a closed-loop system, to which model predictive control was applied without a-priori guarantee of stability.Matteo RubagottiLuca ZaccarianAlberto Bemporadalberto.bemporad@imtlucca.it2016-10-10T15:08:08Z2016-10-10T15:08:08Zhttp://eprints.imtlucca.it/id/eprint/3583This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/35832016-10-10T15:08:08ZReal-time model predictive control based on dual gradient projection: Theory and fixed-point FPGA implementationThis paper proposes a method to design robust model predictive control (MPC) laws for discrete-time linear systems with hard mixed constraints on states and inputs, in case of only an inexact solution of the associated quadratic program is available, because of real-time requirements. By using a recently proposed dual gradient-projection algorithm, it is proved that the discrepancy of the optimal control law as compared with the obtained one is bounded even if the solver is implemented in fixed-point arithmetic. By defining an alternative MPC problem with tightened constraints, a feasible solution is obtained for the original MPC problem, which guarantees recursive feasibility and asymptotic stability of the closed-loop system with respect to a set including the origin, also considering the presence of external disturbances. The proposed MPC law is implemented on a field-programmable gate array in order to show the practical applicability of the method.Matteo RubagottiPanagiotis PatrinosAlberto GuiggianiAlberto Bemporadalberto.bemporad@imtlucca.it2014-10-22T09:53:27Z2014-10-22T10:00:58Zhttp://eprints.imtlucca.it/id/eprint/2331This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/23312014-10-22T09:53:27ZStabilizing linear model predictive control under inexact numerical optimizationThis note describes a model predictive control (MPC) formulation for discrete-time linear systems with hard constraints on control and state variables, under the assumption that the solution of the associated quadratic program is neither optimal nor satisfies the inequality constraints. This is common in embedded control applications, for which real-time constraints and limited computing resources dictate restrictions on the possible number of on-line iterations that can be performed within a sampling period. The proposed approach is rather general, in that it does not refer to a particular optimization algorithm, and is based on the definition of an alternative MPC problem that we assume can only be solved within bounded levels of suboptimality, and violation of the inequality constraints. By showing that the inexact solution is a feasible suboptimal one for the original problem, asymptotic or exponential stability is guaranteed for the closed-loop system. Based on the above general results, we focus on a specific dual accelerated gradient-projection method to obtain a stabilizing MPC law that only requires a predetermined maximum number of on-line iterations.Matteo RubagottiPanagiotis Patrinospanagiotis.patrinos@imtlucca.itAlberto Bemporadalberto.bemporad@imtlucca.it2014-07-01T10:26:51Z2015-01-13T12:21:40Zhttp://eprints.imtlucca.it/id/eprint/2224This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/22242014-07-01T10:26:51ZRobust explicit model predictive control via regular piecewise-affine approximationThis paper proposes an explicit model predictive control design approach for regulation of linear time-invariant systems subject to both state and control constraints, in the presence of additive disturbances. The proposed control law is implemented as a piecewise-affine function defined on a regular simplicial partition, and has two main positive features. Firstly, the regularity of the simplicial partition allows one to efficiently implement the control law on digital circuits, thus achieving extremely fast computation times. Moreover, the asymptotic stability (or the convergence to a set including the origin) of the closed-loop system can be enforced a-priori, rather than checked a-posteriori via Lyapunov analysis.Matteo RubagottiDavide BarcelliAlberto Bemporadalberto.bemporad@imtlucca.it2014-03-05T14:12:53Z2014-03-05T14:12:53Zhttp://eprints.imtlucca.it/id/eprint/2176This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/21762014-03-05T14:12:53ZStabilizing embedded MPC with computational complexity guaranteesThis paper describes a model predictive control (MPC) approach for discrete-time linear systems with hard constraints on control and state variables. The finite-horizon optimal control problem is formulated as a quadratic program (QP), and solved using a recently proposed dual fast gradient-projection method. More precisely, in a finite number of iterations of the mentioned optimization algorithm, a solution with bounded levels of infeasibility and suboptimality is determined for an alternative problem. This solution is shown to be a feasible suboptimal solution for the original problem, leading to exponential stability of the closed-loop system. The proposed strategy is particularly useful in embedded control applications, for which real-time constraints and limited computing resources can impose tight bounds on the possible number of iterations that can be performed within the scheduled sampling time.Matteo RubagottiPanagiotis Patrinospanagiotis.patrinos@imtlucca.itAlberto Bemporadalberto.bemporad@imtlucca.it2013-10-16T14:28:49Z2014-03-05T13:29:47Zhttp://eprints.imtlucca.it/id/eprint/1835This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/18352013-10-16T14:28:49ZLow-complexity piecewise-affine virtual sensors: theory and designThis paper is focused on the theoretical development and the hardware implementation of low-complexity piecewise-affine direct virtual sensors for the estimation of unmeasured variables of interest of nonlinear systems. The direct virtual sensor is designed directly from measured inputs and outputs of the system and does not require a dynamical model. The proposed approach allows one to design estimators which mitigate the effect of the so-called ‘curse of dimensionality’ of simplicial piecewise-affine functions, and can be therefore applied to relatively high-order systems, enjoying convergence and optimality properties. An automatic toolchain is also presented to generate the VHDL code describing the digital circuit implementing the virtual sensor, starting from the set of measured input and output data. The proposed methodology is applied to generate an FPGA implementation of the virtual sensor for the estimation of vehicle lateral velocity, using a hardware-in-the-loop setting.Matteo RubagottiTomaso PoggiAlbert OliveriCarlo A. PascucciAlberto Bemporadalberto.bemporad@imtlucca.itMarco Storace2013-09-30T12:23:37Z2013-09-30T12:23:37Zhttp://eprints.imtlucca.it/id/eprint/1811This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/18112013-09-30T12:23:37ZStability and Invariance Analysis of Uncertain Discrete-Time Piecewise Affine SystemsThis note proposes a method to analyze uniform asymptotic stability and uniform ultimate boundedness of uncertain piecewise affine systems whose dynamics are only defined in a bounded and possibly non-invariant set X of states. The approach relies on introducing fake dynamics outside X and on synthesizing a piecewise affine and possibly discontinuous Lyapunov function via linear programming. The existence of such a function proves stability properties of the original system and allows the determination of a region of attraction contained in X. The procedure is particularly useful in practical applications for analyzing the stability of piecewise affine control systems that are only defined over a bounded subset X of the state space, and to determine whether for a given set of initial conditions the trajectories of the state vector remain within the domain X.Matteo RubagottiSergio TrimboliAlberto Bemporadalberto.bemporad@imtlucca.it2013-02-20T10:52:50Z2013-02-20T10:52:50Zhttp://eprints.imtlucca.it/id/eprint/1487This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/14872013-02-20T10:52:50ZApproximate Explicit MPC on Simplicial Partitions with Guaranteed Stability for Constrained Linear SystemsThis paper proposes an approximate explicit model predictive control design approach for regulating linear time-invariant systems subject to both state and control constraints. The proposed control law is implemented as a piecewise-affine function defined on a regular simplicial partition, and has two main positive features. First, the regularity of the simplicial partition allows a very efficient implementation of the control law on digital circuits, with computation performed in tens of nanoseconds. Second, the asymptotic stability of the closed-loop system is enforced a priori by design.Matteo RubagottiDavide BarcelliAlberto Bemporadalberto.bemporad@imtlucca.it2013-02-13T07:46:55Z2013-02-13T07:46:55Zhttp://eprints.imtlucca.it/id/eprint/1472This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/14722013-02-13T07:46:55ZStability analysis of discrete-time piecewise-affine systems over non-invariant domainsThis paper analyzes stability of discrete-time piecewise-affine systems defined on non-invariant domains. An algorithm based on linear programming is proposed, in order to prove the exponential stability of the origin and to find a positively invariant estimate of the region of attraction. The theoretical results are based on the definition of a piecewise-affine, possibly discontinuous, Lyapunov function. The proposed method presents a relatively low computational burden, and is proven to lead to feasible solutions in a broader range of cases with respect to a previously proposed approach.Matteo RubagottiLuca ZaccarianAlberto Bemporadalberto.bemporad@imtlucca.it2013-02-12T12:11:05Z2013-02-12T12:11:05Zhttp://eprints.imtlucca.it/id/eprint/1471This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/14712013-02-12T12:11:05ZPiecewise affine direct virtual sensors with Reduced ComplexityIn this paper, a piecewise-affine direct virtual sensor is proposed for the estimation of unmeasured outputs of nonlinear systems whose dynamical model is unknown. In order to overcome the lack of a model, the virtual sensor is designed directly from measured inputs and outputs. The proposed approach generalizes a previous contribution, allowing one to design lower-complexity estimators. Indeed, the reduced-complexity approach strongly reduces the effect of the so-called "curse of dimensionality", and can be applied to relatively high-order systems, while enjoying all the convergence and optimality properties of the original approach.Matteo RubagottiTomaso PoggiAlberto Bemporadalberto.bemporad@imtlucca.itMarco Storace2012-10-15T08:09:17Z2012-10-15T08:09:17Zhttp://eprints.imtlucca.it/id/eprint/1401This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/14012012-10-15T08:09:17ZMOBY-DIC: A MATLAB Toolbox for Circuit-Oriented Design of Explicit MPCThis paper describes a MATLAB Toolbox for the integrated design of Model Predictive Control (MPC) state-feedback control laws and the digital circuits implementing
them. Explicit MPC laws can be designed using optimal and sub-optimal formulations, directly taking into account the specifications of the digital circuit implementing the control law (such as latency and size), together with the usual control specifications (stability, performance,
constraint satisfaction). Tools for a-posteriori stability analysis of the closed-loop system, and for the simulation of the circuit in Simulink, are also included in the toolbox.Alberto OliveriDavide BarcelliAlberto Bemporadalberto.bemporad@imtlucca.itBart GenuitW.P.M.H. HeemelsTomaso PoggiMatteo RubagottiMarco Storace2012-03-07T10:51:31Z2013-09-30T12:32:32Zhttp://eprints.imtlucca.it/id/eprint/1229This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/12292012-03-07T10:51:31ZA sub-optimal second order sliding mode controller for systems with saturating actuatorsIn this technical note, the problem of the possible saturation of the continuous control variable in the sub-optimal second order sliding mode controller, applied to systems with saturating actuators, is addressed. It is proved that during the sliding phase, if basic assumptions are made, the continuous control variable never saturates. On the contrary, during the reaching phase, the presence of saturating actuators can make the steering of the sliding variable to zero in a finite time not always guaranteed. In the present technical note, the original algorithm is modified in order to solve this problem: a new strategy is proposed, which proves to be able to steer the sliding variable to zero in a finite time in spite of the presence of saturating actuators.Antonella FerraraMatteo Rubagotti2012-03-06T15:10:50Z2013-09-30T12:24:26Zhttp://eprints.imtlucca.it/id/eprint/1227This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/12272012-03-06T15:10:50ZSliding mode control of a mobile robot for dynamic obstacle
avoidance based on a time-varying harmonic potential fieldIn this paper, a harmonic potential field method for dynamic environments is proposed to generate an on-line reference trajectory for a wheeled mobile robot. A sliding mode controller is used to make the robot move along the prescribed trajectory determined by the gradient lines. The potential field is modified on-line, in order to make the robot avoid the collision with obstacles which move along non a-priori known trajectories with time-varying speed. The mechanism through which the field is modified is based on the so-called ‘collision cone’ concept.Antonella FerraraMatteo Rubagotti2012-03-06T15:01:57Z2013-09-30T12:24:52Zhttp://eprints.imtlucca.it/id/eprint/1226This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/12262012-03-06T15:01:57ZGradient tracking based second order sliding mode control
of a wheeled vehicleAntonella FerraraMatteo Rubagotti2012-03-06T14:41:51Z2013-09-30T12:25:11Zhttp://eprints.imtlucca.it/id/eprint/1224This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/12242012-03-06T14:41:51ZRobust nonlinear MPC with integral sliding mode for systems with matched disturbancesMatteo RubagottiDavide Martino RaimondoAntonella FerraraLalo Magni2012-03-06T14:31:56Z2013-09-30T12:26:54Zhttp://eprints.imtlucca.it/id/eprint/1223This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/12232012-03-06T14:31:56ZA sub-optimal second order sliding mode controller for current-fed induction motorsA second order sliding mode controller for current-fed induction motors is proposed in this paper. The design of the controller is based on a reduced order model of the machine, and the control variables are non-discontinuous currents, obtained integrating a discontinuous auxiliary control signal. The phase voltages are then generated using a current regulated pulse width modulation inverter, while the rotor flux value is obtained by means of a simple observer. The convergence properties of the proposed control strategy are studied in the paper, and verified in simulation.Antonella FerraraMatteo Rubagotti2012-03-06T13:42:41Z2013-09-30T12:26:11Zhttp://eprints.imtlucca.it/id/eprint/1222This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/12222012-03-06T13:42:41ZDiagnosis and prognosis of automotive systems: motivations, history and some resultsThis paper presents an overview of diagnostic needs and methodologies in the automotive field. The field of automotive engineering has seen an explosion in the presence of electronic components and systems on-board vehicles since the 1970s. This growth was initially motivated by the introduction of emissions regulations that led to the widespread application of electronic engine controls. A secondary but important consequence of these developments was the adoption of on-board diagnostics regulations aimed at insiring that emission control systems remained functional for a prescribed period of time (or vehicle mileage). In addition, the presence of micro-controllers on-board the vehicle led to a proliferation of functions implemented through electronic systems and related software, related to safety and customer convenience, creating the need for more sophisticated on-board diagnostics. Today, a significant percentage of the software code in an automobile is devoted to diagnostic functions. This paper presents an overview of diagnostic needs and requirements in the automotive industry, illustrates some of the challenges that are associated with satisfying these requirements and proposes some future directions, in particular with respect to prognostics.Giorgio RizzoniSimona OnoriMatteo Rubagotti2012-03-06T13:33:24Z2013-09-30T12:27:16Zhttp://eprints.imtlucca.it/id/eprint/1221This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/12212012-03-06T13:33:24ZA dynamic obstacle avoidance strategy for a mobile robot based on sliding mode controlIn this paper, a dynamic obstacle avoidance strategy for mobile robots is proposed. The strategy consists of two key elements: an on-line reference generator and a control scheme to make the robot track the reference signals so as to reach a pre-specified goal point. To generate the online reference signals, a harmonic potential field for dynamic environments is exploited. The potential field is modified on-line, in order to make the robot avoid the collision with obstacles which move along non a-priori known trajectories with timevarying speed. The proposed multi-level sliding mode controller is capable of making the robot move tracking the prescribed reference signals determined by the trajectory generator. The simulation results confirm the good performances of this approach.Antonella FerraraMatteo Rubagotti2012-03-06T13:28:10Z2013-09-30T12:25:32Zhttp://eprints.imtlucca.it/id/eprint/1220This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/12202012-03-06T13:28:10ZRobust model predictive control of continuous-time sampled-data nonlinear systems with integral sliding modeA hierarchical Nonlinear Model Predictive Control (NMPC) scheme with guaranteed Input-to-State-practical- Stability (ISpS) is proposed. The controller is formed by an Integral Sliding Mode (ISM) controller and a NMPC one. The ISM, relying on the knowledge of the nominal continuous-time model of the system and of the piecewise constant control signal generated by the NMPC produces a control action aimed at reducing the difference between the dynamics of the nominal closed-loop system and the actual evolution of the state. The NMPC in this way can be designed based on a system with reduced uncertainty. In order to prove the stability of the overall control scheme, some general Regional ISpS results for continuous-time systems are proven.Matteo RubagottiDavide Martino RaimondoAntonella FerraraLalo Magni2012-03-06T13:19:59Z2013-09-30T12:26:33Zhttp://eprints.imtlucca.it/id/eprint/1219This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/12192012-03-06T13:19:59ZAutomotive battery prognostics using dual Extended Kalman FilterThis paper proposes a strategy for estimating the remaining useful life of automotive batteries based on dual Extended Kalman Filter. A nonlinear model of the battery is exploited for the on-line estimation of the State of Charge, and this information is used to evaluate the actual capacity and predict its future evolution, from which an estimate of the remaining useful life is obtained with suitable margins of uncertainty. Simulation results using experimental data from lead-acid batteries show the effectiveness of the approachMatteo RubagottiSimona OnoriGiorgio Rizzoni2012-03-06T13:08:24Z2013-09-30T12:28:55Zhttp://eprints.imtlucca.it/id/eprint/1218This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/12182012-03-06T13:08:24ZOptimal disturbance rejection via integral sliding mode control for uncertain systems in regular formThis paper considers the problem of using an integral sliding mode strategy to reduce the disturbance terms acting on nonlinear systems in regular form. It is proved that the definition of a suitable sliding manifold and the generation of sliding modes upon it can guarantee the minimization of the disturbance terms. Simulation examples shows the effectiveness of the proposal.Matteo RubagottiAntonio EstradaFernando CastanosAntonella FerraraLeonid Fridman2012-03-06T12:14:28Z2013-09-30T12:28:34Zhttp://eprints.imtlucca.it/id/eprint/1217This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/12172012-03-06T12:14:28ZSecond order sliding mode control of a perturbed double integrator with state constraintsThis paper introduces a second order sliding mode controller for double integrators subject to external disturbances and model uncertainties, with both control and state constraints. The proposed control strategy proves to be able to robustly steer the system state to zero in a finite time, fulfilling the state constraints in spite of the uncertainties, provided that the initial state is inside a given region. The effectiveness of the proposal is then tested on a simulation example.Matteo RubagottiAntonella Ferrara2012-03-06T12:06:46Z2013-09-30T12:27:36Zhttp://eprints.imtlucca.it/id/eprint/1216This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/12162012-03-06T12:06:46ZA nonlinear model predictive control scheme with multirate integral sliding modeIn this paper, a hierarchical multirate control scheme for nonlinear discrete-time systems is proposed, composed of a robust model predictive controller (MPC) and a multirate integral sliding mode (MISM) controller. In particular, the MISM controller acts at a faster sampling time than the MPC controller, and reduces the effect of model uncertainties and external disturbances, in order to obtain, at the next sampling instant of the MPC controller, a value of the system state that is as close as possible to the nominal one. To obtain this result, the control variable is composed of two parts: one generated by the MPC controller, and the other by the MISM controller. The a-priori reduction of the disturbance terms turns out to be very useful in order to improve the convergence properties of the MPC controller.Matteo RubagottiDavide Martino RaimondoColin Neil JonesLalo MagniAntonella FerraraManfred Morari2012-03-06T11:57:29Z2013-09-30T12:29:22Zhttp://eprints.imtlucca.it/id/eprint/1214This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/12142012-03-06T11:57:29ZA smart embedded control unit for electro-hydraulic aircraft actuatorsThe design and experimental characterization of a novel electronic control unit for fly-by-wire aircraft actuators are presented. Thanks to a carefully-engineered compact volume, it is embedded in the actuator body, providing local closed-loop control. Various digital control laws can be implemented in the easily reconfigurable digital platform. After system modeling and tuning, a variable-gain controller has been selected. Beyond reduction of weight (900g), power dissipation (7W) and cabling connections (required only for power supply and digital communication bus), the advantages provided by this smart unit are both in terms of performance and safety improvement. In fact, fast (1Hz) and precise (1mm resolution, 2mm accuracy, no overshoot) closed-loop linear displacement regulation is here demonstrated. Furthermore, this robust and rugged unit is endowed with self-diagnostic capabilities: fault detection of all critical electronic and electro/mechanical sections is implemented by dedicated analog circuits. It is suitable for fully-electrical and hybrid electro-hydraulic actuators. Extensive thermal characterization has confirmed the fulfillment of specifications over the whole -40 C° ÷ +70 C° operating range.Marco CarminatiMatteo RubagottiRiccardo GrassettiGiorgio FerrariMarco Sampietro2012-03-05T13:49:24Z2013-09-30T12:30:10Zhttp://eprints.imtlucca.it/id/eprint/1213This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/12132012-03-05T13:49:24ZSliding mode observers for sensorless control of current-fed induction motorsThis paper presents the use of a higher order sliding mode scheme for sensorless control of induction motors. The second order sub-optimal control law is based on a reduced-order model of the motor, and produces the references for a current regulated PWM inverter. A nonlinear observer structure, based on Lyapunov theory and on different sliding mode techniques (first order, sub-optimal and super-twisting) generates the velocity and rotor flux estimates necessary for the controller, based only on the measurements of phase voltages and currents. The proposed control scheme and observers are tested on an experimental setup, showing a satisfactory performance.Daniele BulloAntonella FerraraMatteo Rubagotti2012-03-05T10:58:40Z2013-02-12T12:12:49Zhttp://eprints.imtlucca.it/id/eprint/1211This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/12112012-03-05T10:58:40ZStability and invariance analysis of uncertain PWA systems based on linear programmingThis paper analyzes stability of discrete-time uncertain piecewise-affine systems whose dynamics are defined on a bounded set χ; that is not necessarily invariant. The objective is to prove the uniform asymptotic stability of the origin and to find an invariant domain of attraction. This goal is attained by defining a suitable extended dynamics (which is partially fictitious), and by using a numerical procedure based on linear programming. The theoretical results are based on the definition of a piecewise-affine, possibly discontinuous, Lyapunov function.Sergio TrimboliMatteo RubagottiAlberto Bemporadalberto.bemporad@imtlucca.it2012-03-02T15:49:32Z2013-09-30T12:32:05Zhttp://eprints.imtlucca.it/id/eprint/1210This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/12102012-03-02T15:49:32ZSecond-order sliding-mode control of a mobile robot based on a harmonic potential fieldThe problem of controlling an autonomous wheeled vehicle which must move in its operative space and reach a prescribed goal point avoiding the collision with the obstacles is dealt with. To comply with the non- holonomic nature of the system, a gradient-tracking approach is followed, so that a reference velocity and orientation are suitably generated during the vehicle motion. To track such references, two control laws are designed by suitably transforming the system model into a couple of auxiliary second-order uncertain systems, relying on which second-order sliding modes can be enforced. As a result, the control objective is attained by means of a continuous control law, so that the problems due to the so-called chattering effect, such as the possible actuators wear or the induction of vibrations, typically associated with the use of sliding-mode control, are circumvented.Antonella FerraraMatteo Rubagotti2012-03-02T15:42:26Z2013-09-30T12:25:51Zhttp://eprints.imtlucca.it/id/eprint/1209This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/12092012-03-02T15:42:26ZA sub-optimal second order sliding mode controller for systems with saturating actuatorsIn this paper, the problem of the possible saturation of the continuous control variable in the sub-optimal second order sliding mode controller applied to relative degree one systems with saturating actuators is addressed. It is proved that during the sliding phase, if basic assumptions are made, the continuous control variable never saturates, while, during the reaching phase, the presence of saturating actuators can make the steering of the sliding variable to zero in finite time not always guaranteed. In the present paper, the original algorithm is modified in order to solve this problem: a new strategy is proposed, which proves to be able to steer the sliding variable to zero in a finite time in spite of the presence of saturating actuators.Antonella FerraraMatteo Rubagotti2012-03-02T15:30:33Z2013-09-30T12:33:14Zhttp://eprints.imtlucca.it/id/eprint/1208This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/12082012-03-02T15:30:33ZRobust model predictive control with integral sliding mode in continuous-time sampled-data nonlinear systemsThis paper proposes a control strategy for nonlinear constrained continuous-time uncertain systems which combines robust model predictive control (MPC) with sliding mode control (SMC). In particular, the so-called Integral SMC approach is used to produce a control action aimed to reduce the difference between the nominal predicted dynamics of the closed-loop system and the actual one. In this way, the MPC strategy can be designed on a system with a reduced uncertainty. In order to prove the stability of the overall control scheme, some general regional input-to-state practical stability results for continuous-time systems are proved.Matteo RubagottiDavide Martino RaimondoAntonella FerraraLalo Magni2012-03-02T15:10:30Z2013-09-30T12:37:32Zhttp://eprints.imtlucca.it/id/eprint/1207This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/12072012-03-02T15:10:30ZTime-optimal sliding-mode control of a mobile robot in a dynamic environmentIn this study, an original strategy to control a mobile robot in a dynamic environment is presented. The strategy consists of two main elements. The first is the method for the online trajectory generation based on harmonic potential fields, capable of generating velocity and orientation references, which extends classical results on harmonic potential fields for the case of static environments to the case when the presence of a moving obstacle with unknown motion is considered. The second is the design of sliding-mode controllers capable of making the controlled variables of the robot track in a finite minimum time both the velocity and the orientation references.Matteo RubagottiMarco L. Della VedovaAntonella Ferrara2012-03-02T14:54:31Z2013-09-30T12:37:55Zhttp://eprints.imtlucca.it/id/eprint/1206This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/12062012-03-02T14:54:31ZIntegral sliding mode control for nonlinear systems with matched and unmatched perturbationsWe consider the problem of designing an integral sliding mode controller to reduce the disturbance terms that act on nonlinear systems with state-dependent drift and input matrix. The general case of both, matched and unmatched disturbances affecting the system is addressed. It is proved that the definition of a suitable sliding manifold and the generation of sliding modes upon it guarantees the minimization of the effect of the disturbance terms, which takes place when the matched disturbances are completely rejected and the unmatched ones are not amplified. A simulation of the proposed technique, applied to a dynamically feedback linearized unicycle, illustrates its effectiveness, even in presence of nonholonomic constraints.Matteo RubagottiAntonio EstradaFernando CastanosAntonella FerraraLeonid Fridman2012-03-02T14:47:20Z2013-09-30T12:38:13Zhttp://eprints.imtlucca.it/id/eprint/1205This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/12052012-03-02T14:47:20ZHigh-Speed piecewise affine virtual sensorsThis paper proposes piecewise affine (PWA) virtual sensors for the estimation of unmeasured variables of nonlinear systems with unknown dynamics. The estimation functions are designed directly from measured inputs and outputs and have two important features. First, they enjoy convergence and optimality properties, based on classical results on parametric identification. Second, the PWA structure is based on a simplicial partition of the measurement space and allows one to implement very effectively the virtual sensor on a digital circuit. Due to the low cost of the required hardware for the implementation of such a particular structure and to the very high sampling frequencies that can be achieved, the approach is applicable to a wide range of industrial problems.Tomaso PoggiMatteo RubagottiAlberto Bemporadalberto.bemporad@imtlucca.itMarco Storace2012-03-02T14:37:36Z2015-05-12T13:23:25Zhttp://eprints.imtlucca.it/id/eprint/1203This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/12032012-03-02T14:37:36ZModeling and control of an airbrake electro-hydraulic smart actuatorIn this paper, an accurate model of an airbrake electro-hydraulic smart actuator is obtained by physical considerations, and then different control strategies (variable-gain proportional control, PT1 control with switching integrator, and second order sub-optimal sliding mode control) are proposed and analyzed. This application is innovative in the avionic field, and is one of the first attempts to realize a fly-by-wire system for airbrakes, oriented to its immediate employment and installation on current aircraft. The project was carried on with the participation of the Italian Ministry of Defense, and was commissioned to MAG, a leading provider of integrated systems and aviation services for aerospace.Matteo RubagottiMarco CarminatiGiampiero ClementeRiccardo GrassettiAntonella Ferrara2011-07-29T10:52:58Z2013-09-30T12:29:47Zhttp://eprints.imtlucca.it/id/eprint/740This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/7402011-07-29T10:52:58ZStability and invariance analysis of approximate explicit MPC based on PWA Lyapunov functionsFor piecewise affine (PWA) systems whose dynamics are only defined in a bounded and possibly non-invariant set X, this paper proposes a numerical approach to analyze the stability of the origin and to find a region of attraction. The approach relies on introducing fake dynamics outside X and on synthesizing a piecewise affine and possibly discontinuous Lyapunov function on a larger bounded set containing X by solving a linear program. The existence of a solution proves that the origin is an asymptotically stable equilibrium of the original PWA system and determines a region of attraction contained in X. The procedure is particularly useful in practical applications for analyzing a posteriori the stability properties of approximate explicit model predictive control laws defined over a bounded set X of states, and to determine whether, for a given set of initial states, the closed-loop system evolves within the domain X where the control law is defined.Matteo RubagottiSergio TrimboliDaniele Bernardinidaniele.bernardini@imtlucca.itAlberto Bemporadalberto.bemporad@imtlucca.it