LPV observer and control design methods for vehicle dynamics

International audienc

Memory Resilient Gain-scheduled State-Feedback Control of Uncertain LTI/LPV Systems with Time-Varying Delays

The stabilization of uncertain LTI/LPV time delay systems with time varying delays by state-feedback controllers is addressed. At the difference of other works in the literature, the proposed approach allows for the synthesis of resilient controllers with respect to uncertainties on the implemented delay. It is emphasized that such controllers unify memoryless and exact-memory controllers usually considered in the literature. The solutions to the stability and stabilization problems are expressed in terms of LMIs which allow to check the stability of the closed-loop system for a given bound on the knowledge error and even optimize the uncertainty radius under some performance constraints; in this paper, the $\mathcal{H}_\infty$ performance measure is considered. The interest of the approach is finally illustrated through several examples

An LP V/H∞ integrated Vehicle Dynamic Controller

International audienceThis paper is concerned with the design and analysis of a new multivariable LP V /H∞ (Linear Parameter Varying) robust control design strategy for Global Chassis Control. The main objective of this study is to handle critical driving situations by activating several controller subsystems in a hierarchical way. The proposed solution consists indeed in a two-step control strategy that uses semi-active suspensions, active steering and electro-mechanical braking actuators. The main idea of the strategy is to schedule the 3 control actions (braking, steering and suspension) according to the driving situation evaluated by a specific monitor. Indeed, on one hand, rear braking and front steering are used to enhance the vehicle yaw stability and lateral dynamics, and on the other hand, the semi-active suspensions to improve comfort and car handling performances. Thanks to the LP V /H∞ framework, this new approach allows to reach a smooth coordination between the various actuators, to ensure robustness and stability of the proposed solution, and to significantly improve the vehicle dynamical behavior. Simulations have been performed on a complex full vehicle model which has been validated using data obtained from experimental tests on a real Renault Mégane Coupé. Moreover, the suspension system uses Magneto-Rheological dampers whose characteristics have been obtained through experimental identification tests. A comparison between the proposed LPV/H∞ control strategy and a classical LTI/H∞ controller is performed using the same simulation scenarios and confirms the effectiveness of this approach

A LPV/Hinf fault tolerant control of vehicle roll dynamics under semi-active damper malfunction

International audienceThis paper proposes a LPV/Hinf fault tolerant control strategy for roll dynamics handling under semi-active damper's malfunction. Indeed, in case of damper's malfunction, a lateral load transfer is generated, that amplifies the risks of vehicle roll over. In this study, the suspension systems efficiency is monitored through the lateral (or longitudinal) load transfer induced by a damper's malfunction. The information given by the monitoring system is used in a partly fixed LPV/Hinf controller structure that allows to manage the distribution of the four dampers forces in order to handle the over load caused by one damper's malfunction. The proposed LPV/Hinf controller then uses the 3 remaining healthy semi-active dampers in a real time reconfiguration. Moreover, the performances of the car vertical dynamics (roll, bounce, pitch) are adapted to the varying parameter given by the monitoring of the suspension system efficiency, which allows to modify online the damping properties (soft/hard) to limit the induced load transfer. Simulations are performed on a complex nonlinear full vehicle model, equipped by 4 magneto-rheological semi-active dampers. This vehicle undergoes critical driving situations, and only one damper is considered faulty at ones. The simulation results show the reliability and the robustness of the proposed solution

Fault detection for LPV systems: Loop shaping H− approach

International audienceThis paper addresses a method for fault detection (FD) in linear parameters varying (LPV) systems by maximizing the fault to residual sensitivity. It uses the newly developed H − index properties and minimizing the well known H ∞ norm for worst case uncertainties and disturbance attenuation. A loop shaping approach for the H − FD problem is proposed. The multi-objectives problem is formulated as Linear Matrix Inequalities (LMI) problem for polytopic systems. An application on lateral vehicle dynamics is given as an illustrative example for this approach

A Full-Block S-procedure application to delay-dependent state-feedback control of uncertain time-delay systems

International audienceThis paper deals about the robust stabilization of uncertain systems with timevarying state delays in the delay dependent framework. The system is represented using LFR and stability is deduced from Lyapunov-Krasovskii theorem and full-block S-procedure. We derive sufficient conditions to the existence of a robust H-infinity state-feedback control law. As this sufficient condition is expressed in terms of nonlinear matrix inequality (NMI), we propose a relaxation based on the cone complementary algorithm which is known to lead to good results for such problems. We show the efficiency of our method trough an example

A motion-scheduled LPV control of full car vertical dynamics

International audienceIn this paper, we present a new Linear Parameter Varying LPV/H ∞ motion adaptive suspension controller that takes into account the three main motions of the vehicle vertical dynamics: bounce, roll and pitch motions. The new approach aims, by using a detection of the vehicle motions, at designing a controller which is able to adapt the suspension forces in the four corners of the vehicle according to the dynamical motions, in order to mitigate these vertical dynamics which could be stimulated by the road-induced vibrations, making a tight turn or an evasive manoeuvre, braking or accelerating. The main idea of this strategy is to use three scheduling parameters, representative of the motion distribution in the car dynamics, to adapt and distribute efficiently the suspension actuators. The motion detection strategy is based on the supervison of load transfer distribution. A full 7 degree of freedom (DOF) vertical model is used to describe the body motion (chassis and wheels), and to synthesize the LPV controller. The controller solution is derived in the framework of the LPV/H ∞ and based on the LMI solution for polytopic systems. Some simulations are presented in order to demonstrate the effectiveness of this approach

Power sources coordination through multivariable LPV/Hinf control with application to multi-source electric vehicles

International audienceIn this paper the problem of multi-source power sharing strategy within electric vehicles is considered. Three different kinds of power sources - fuel cell, battery and supercapacitor - compose the power supply system, where all sources are current-controlled and paralleled together with their associated DC-DC converters on a common DC-link. The DC-link voltage must be regulated regardless of load variations corresponding to the driving cycle. The proposed strategy is a robust control solution using a MIMO LPV/H-inf controller which provides the three current references with respect to source frequency characteristics. The selection of the weighting functions is guided by a genetic algorithm whose optimization criterion expresses the frequency separation requirements. A reduced-order version of the LPV/H-inf controller is also proposed to handle an embedded implementation with limited computational burden. The nonlinear multi-source system is simulated in MATLAB® / Simulink® using two different types of driving cycles: the driving cycle of IFSTTAR (Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux) and a constant load profile used in order to illustrate system steady-state behaviour. Simulation results show good performance in supplying the load at constant DC-link voltage according to user-configured frequency-separation power sharing strategy. When assessed against the classical-PI-based filtering strategy taken as base-line, the proposed strategy offers the possibility of integrating a variety of constraints into a systematic design procedure, whose result guarantees stability and performance robustness

Commande MIMO LPV /H ∞ de suspension semi-active

National audienceCet article présente une nouvelle commande LPV /H∞ de suspension semi-active qui prend en compte les trois mouvements principaux de la dynamique verticale du véhicule (rebond, roulis et tangage) qui affectent le confort des passagers. La nouvelle approche, utilisant la détection des mouvements du véhicule, a pour objectif de concevoir un contrôleur qui adapte les forces de suspension dans les quatre coins selon les mouvements du véhicule, pour atténuer les vibrations induites par la route. L' idée principale de cette stratégie est d'utiliser trois paramètres variants, représentant la distribution de mouvement dans la dynamique de la voiture, afin d'adapter et distribuer efficacement les actionneurs de suspension. La stratégie de détection du mouvement se base sur une méthode de calcul energétique [20]. Un modèle vertical à 7 degrés de liberté (DOF) du véhicule est utilisé pour décrire les mouvements du châssis et des roues, et de synthétiser le régulateur LPV. Ce régulateur est conçu dans le cadre H∞/LPV pour les systèmes polytopiques. Des résultats de simulation sont présentés pour valider l'approche proposée

An LPV Fault Tolerant control for semi-active suspension -scheduled by fault estimation

International audienceIn this paper, a novel fault tolerant control is proposed to accommodate damper faults (oil leakages) in a semi-active suspension system based on a quarter-car vehicle model. The fault accommodation is based on the Linear Parameter Varying (LPV) control strategy and involved in 2 steps. At first, a fast time-varying fault is estimated by using the fast adaptive fault estimation (FAFE) algorithm and based on an unknown input adaptive observer. Thanks to information about the estimated fault, the dissipativity domain of the semi-active suspension is adapted according to the fault. Then a single LPV fault tolerant controller is developed to manage the system performances. The controller solution, derived in the LPV/H ∞ framework, is based on the LMI solution for polytopic systems. Some simulation results are presented that show the effectiveness of this approach