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

Adaptive Space-Time Distributed Parameter and Input Estimation in Heat Transport with Unknown Bounds

International audienceIn this paper, we discuss on-line adaptive estimation of distributed diffusion and source term coefficients for a non-homogeneous linear parabolic partial differential equation describing heat transport. An estimator is defined in the infinite-dimensional framework having the system state and the parameters' estimate as its states. Our scheme allows to estimate spatially distributed and space-time distributed parameters. While the parameters convergence depends on the plant signal richness assumption, the state convergence is established using the Lyapunov approach. Since the estimator is infinite- dimensional, the b-splines Galerkin finite element method is used to implement it. In silico simulations are provided to illustrate the performance of the proposed approach

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 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

Actuator fault estimation based on a switched LPV extended state observer

article en cours de soumission à une revueActuator fault estimation problem is tackled in this paper. The actuator faults are modeled in the form of multiplicative faults by using effectiveness factors representing the loss of efficiency of the actuators. The main contribution of this paper lies in the capability of dealing with the presented problem by using a switched LPV observer approach. The LTI system in the presence of faulty actuators is rewritten as a switched LPV system by considering the control inputs as scheduling parameters. Then, the actuator faults and the system states are estimated using a switched LPV extended observer. The observer gain is derived, based on the LMIs solution for the switched LPV systems. The presented actuator fault estimation approach is validated by two illustrative examples, the first one about a damper fault estimation of a semi-active suspension system, and the second one concerned to fault estimations on a multiple actuators system

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

A switched LPV observer for actuator fault estimation

International audienceIn this paper, an actuator fault estimation problem is tackled, based on the LPV approach. First, the actuator fault is modeled in the form of a multiplicative fault by using a constant coefficient representing the loss of efficiency of the actuator's power α. Therefore, the estimation of a time varying faulty actuator can be transformed into the estimation of a constant coefficient α. Then, the faulty system is rewritten in the form of a switched LPV system. The coefficient α and the system states are estimated using an extended switched observer. The stability and performance of the observer is ensured considering a switched time-dependent Lyapunov function. The observer gains are derived based on LMI solutions for polytopic switched systems. Some simulation results are presented that show the effectiveness of this approach

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

Comparison of observer approaches for actuator fault estimation in semi-active suspension systems

International audienceIn this paper, the actuator fault estimation problem of semi-active suspension systems is considered. For instance, an oil leakage in the damper could cause a reduction of the damping force. The fault estimation requires a modeling of the damper fault (both multiplicative and additive fault models can be used). Three observer-based approaches are compared for fault estimation: an observer using fast adaptive fault estimation (FAFE) approach (used for estimation of additive faults), a parametric adaptive observer (AO) and a switched LPV observer (LPVO) (both intended to estimate mulplicative faults); Since the damper fault estimation is strongly affected by the unknown road disturbances, an H ∞ performance objective is used to reduce the effect of disturbances on the estimation error for performance assessment. Some simulations are performed on a quarter car model to validate these methodologies and a comparison is then given to shows the interest of each method. Keywords: Fault estimation, semi-active damper fault, adaptive observer, fast fault adaptive estimation, LPV observer

Comparison of several robust observers for automotive damper force estimation

International audienceThis paper aims at comparing three robust observers used to estimate the damping force of of elec-trorheological (ER) damper in a vehicle suspension system. Firstly, a nonlinear quarter-car model, augmented with a first-order dynamical nonlinear damper model, is developed. The first two methods are designed considering the nonlinearity as an unknown input and minimizing the effect of the unknown input disturbances (including nonlinearity term, measurment noise, unknown road profile) on the estimation errors, by using an H 2 and H ∞ criterion, respectively. The latter method is to only minimize the effects of measurement noises and road profiles on the state variable estimation errors by using a H ∞ criterion while the nonlinearity is bounded through a Lipschitz condition. Two low-cost sensors signals (two accelerometers data from the sprung mass and the unsprung mass) are considered as inputs for the observer designs. Finally, the observers are implemented on the INOVE testbench from GIPSA-lab (1/5-scaled real vehicle) to assess and compare experimentally the performances of the approaches. Both simulations and experimental results demonstrate a better effectiveness of the latter observer in terms of the ability of estimating the damper force in real-time despite the nonlinearity, the measurement noises and the road disturbances