Robust fault detection for Uncertain Unknown Inputs LPV system

International audienceThis paper focuses on robust fault residual generation for Uncertain Unknown Inputs Linear Parameter Varying (U-LPV) systems. Firstly, the problem is addressed in standard LPV systems based on the adaptation of the parity-space approach. The main objective of this approach is to design a scheduled parity matrix according to the scheduling parameters. It results a perfectly decoupled parity matrix face to the system states. Then, the major contribution of this paper relies on the extension to U-LPV systems. Since most of models which represent practical/real systems are subject to parameters variation, unmodeled dynamics and unknown inputs, the approach is clearly justified. The residual synthesis is rewritten in terms of a new optimization problem and solved using Linear Matrix Inequalities (LMIs) techniques. An applicative illustration is proposed and rests on a vehicle lateral dynamic system

Deterioration modelling of contact surfaces for a friction drive system

International audienceThis article presents a novel model of surface deterioration for a friction drive. For this basic transmission system, the difference between tangential speeds is linked with the production of contact force and at the same time with an energy transfer that deteriorates the contact surfaces. Thus, an optimal management between health state of components and use of energy resources is required. In a first step, the physics of the system is modeled in a deterministic way. Then, considering either random system parameters or random system inputs and usage, a complete stochastic model for the system deterioration is proposed. The developed model allows to link the deterioration evolution to the inputs and operating modes of the system; to assess the behavior of deterioration in critical stages, such as sharp motion and smooth motion. The advantages to design and to analyze such a model are finally discussed in terms of reliability-adaptive systems

The INOVE ANR 2010 Blan 0308 project: Integrated approach for observation and control of vehicle dynamics

International audienceThis paper presents the INOVE "Integrated approach for observation and control of vehicle dynamics" project. The aim and organization of the project are described and we present some recent results on the proposed integrated approach to design new methodologies for the improvement of the vehicle dynamical behaviour

Road profile estimation using an adaptive Youla- Kučera parametric observer: comparison to real profilers

International audienceRoad profile acts as a disturbance input to the vehicle dynamics and results in undesirable vibrations affecting the vehicle stability. A precise information of this data is mandatory for a better understanding of the vehicle dynamics behavior and active vehicle control systems design. However, direct measurements of the road profile are not trivial for technical and economical reasons, and thus alternative solutions are needed. This paper develops a novel observer, known as virtual sensor, suitable for real-time estimation of the road profile. The developed approach is carried on a quarter-car model and on measurements of the vehicle body. The road elevation is modeled as a sinusoidal disturbance signal acting on the vehicle system. Since this signal has unknown and time-varying characteristics, the proposed estimation method implements an adaptive control scheme based on the internal model principle and on the use of Youla-Kučera (YK) parametrization technique (also known as Q-parametrization). For performances assessment, estimations are comparatively evaluated with respect to measurements issued from Longitudinal Profile Analyzer (LPA) and Inertial Profiler (IP) instruments during experimental trials. The proposed method is also compared to the approach provided in (Doumiati et al. (2011)), where a stochastic Kalman filter is applied assuming a linear road model. Results show the effectiveness and pertinence of the present observation scheme

Attitude control of a gyroscope actuator using event-based discrete-time approach

International audienceIn this paper, a discrete state feedback Linear Quadratic Regulator (LQR) for event-triggered control is presented. To ensure zero steady state error in the case of such controllers, one normally extends the states with an integral action. Instead of using integral action, the idea is to estimate the disturbance causing the steady state error and use this to extend the states. A Lyapunov-based event triggering function is proposed. Practical results using a gyroscope actuator are presented and compared to a classical time-triggered controller. The obtained results demonstrate the simplicity and efficiency of the proposed approach

Event-Based {LQR} with Integral Action

International audienceIn this paper, a state-feedback linear-quadratic regulator (LQR) is proposed for event-based control of a linear system. An interesting property of LQRs is that an optimal response of the system can be obtained in accordance to some specifications, like the actuator limits. An integral action is also added in order to not only restrict the study to null stabilization but also to tracking. The idea is to consider an external control loop and stabilize the integral of the error between the measurement and a desired setpoint to track. However, an event-triggered integral can lead to important overshoots when the interval between two successive events becomes large. Therefore, an exponential forgetting factor of the sampling interval is proposed as a solution to avoid such problems. The whole proposal is tested on a real-time system (a gyroscope) in order to highlight its ability, the reduction of control updates and the respect to the actuator limits

A Novel RPI Set Computation Method for Discrete-time LPV Systems with Bounded Uncertainties

Set invariance plays a fundamental role in the analysis and design of linear systems. This paper proposes a novel method for constructing robust positively invariant (RPI) sets for discrete-time linear parameter varying (LPV) systems. Starting from the stability assumption in the absence of disturbances, we aim to construct the RPI sets for parametric uncertain system. The existence condition of a common quadratic Lyapunov function for all vertices of the polytopic system is relaxed in the present study. Thus the proposed method enlarges the application field of RPI sets to LPV systems. A family of approximations of minimal robust positively invariant(mRPI) sets are obtained by using a shrinking procedure. Finally, the effect of scheduling variables on the size of the mRPI set is analyzed to obtain more accurate set characterization of the uncertain LPV system. A numerical example is used to illustrate the effectiveness of the proposed method

Commande robuste pour une gestion énergétique fonction de l'état de santé de la batterie au sein des véhicules hybrides

Un des enjeux actuels de la réduction des émissions polluantes pour les véhicules automobiles concerne l'utilisation de moyens de propulsion hybride (électrique+thermique). Les problématiques principales, pour l'automatique, sont alors d'optimiser l'efficacité énergétique globale du véhicule, mais aussi d'améliorer les performances du véhicule hybride. Nous envisageons ici de développer des méthodes de commande robuste dans cet objectif, tout en prenant en compte les contraintes liées à la mise en oeuvre pratique.In the recent years, growing public concern has been given both on the energy problem and on the environment problem resulted from dramatically increased vehicles equipped with Internal Combustion Engine (ICE). Subsequently, intensive contributions have been made by the automotive industries and research institutes on vehicles that depend less on the fossil fuels, and introduce less pollutant emissions. This has led to the emergence of environment-friendly and energy-saving vehicles such as the Hybrid Electric Vehicle (HEV) that is usually equipped with one or more additional electric motors and the associated power battery compared with the Conventional vehicles (CVs) propelled solely by the ICE. The key point of an HEV is to design a proper Energy Management Strategy (EMS) that decides how to split the demanded power between the engine and the motor (battery). As the most important and expensive part of an HEV, it is important to take into account battery states, such as battery State of Charge (SOC) and battery ageing, aiming at maintain the optimality of the achieved EMS, as well as prolonging the battery life. In this dissertation, an HEV of parallel structure, which is equipped with a Lithiumion battery is considered. This dissertation is focused on accounting for battery related items, i.e. battery SOC and SOH indicated by battery parameters, in the EMS developments leading to a kind of fault tolerant EMS. Some brief introduction on the control methods and realization approaches involved in this work is presented first, followed by two big parts: the first part is focused on the battery modeling and estimation, while the second part is concerned by the vehicle modeling and few kinds of EMS development methods.SAVOIE-SCD - Bib.électronique (730659901) / SudocGRENOBLE1/INP-Bib.électronique (384210012) / SudocGRENOBLE2/3-Bib.électronique (384219901) / SudocSudocFranceF

Fault Tolerant Strategy for Semi-Active Suspensions with LPV Accommodation

International audienceAbstract--A novel fault tolerant strategy to compensate multiplicative actuator faults (damper oil leakages) in a semiactive suspension system is proposed. The compensation of the lack of damping force caused by a faulty damper is carried on by the remainder three healthy semi-active dampers. Once a faulty damper is detected and isolated by a Fault Detection and Isolation strategy based on parity-space, an estimator is activated to compute the missing damping force to compensate. In order to fulfill the semi-active damper constraints, the fault accommodation is based on the Linear-Parameter Varying (LPV) control strategy. Thus, each corner has a fault estimator and an LPV controller oriented to comfort and road holding. Simulation results show that the proposed fault tolerant semiactive suspension improves the vehicle comfort up to 60% with respect to a controlled suspension without fault-tolerant strategy and 82% with respect to a passive suspension

Adaptive Road Profile Estimation in Semi-Active Car Suspensions

International audienceThe enhancement of the passengers comfort and their safety are part of the constant concerns for car manufacturers. As a solution, the semi-active damping control systems have emerged to adapt the suspension features, where the road profile is one of the most important factors that determine the automotive vehicle performance. Because direct measurements of the road condition represent expensive solutions and, are susceptible to be contaminated, this paper proposes a novel road profile estimator that offers the essential information (road roughness and its frequency) for the adjustment of the vehicle dynamics by using conventional sensors of cars. Based on the Q-parametrization approach, an adaptive observer estimates the dynamic road signal, posteriorly, a Fourier analysis is used to compute online the road roughness condition and perform an ISO 8608 classification. Experimental results on the rear-left corner of a 1:5 scale vehicle, equipped with Electro-Rheological (ER) dampers, have been used to validate the proposed road profile estimation method. Different ISO road classes evaluate online the performance of the road identification algorithm, whose results show that any road can be identified successfully at least 70% with a false alarm rate lower than 5%; the general accuracy of the road classifier is 95%. A second test with variable vehicle velocity shows the importance of the online frequency estimation to adapt the road estimation algorithm to any driving velocity, in this test the road is correctly estimated 868 of 1,042 m (error of 16.7%). Finally, the adaptability of the parametric road estimator to the semi-activeness property of the ER damper is tested at different damping coefficients