Péter Gáspár

Integrated vehicle dynamics control via coordination of active front steering and rear braking

Abstract This paper investigates the coordination of active front steering and rear braking in a driver-assist system for vehicle yaw control. The proposed control system aims at stabilizing the vehicle while achieving a desired yaw rate. During normal driving situations, active steering control is involved for steerability enhancement. However, when the vehicle reaches the handling limits, both steering and braking collaborate together to ensure vehicle stability. The coordination of these actuators is achieved through a suitable gain scheduled LPV (Linear Parameter Varying) controller. The controller is synthesized within the LMI (Linear Matrix Inequalities) framework, while warranting robust H ∞ performances. Time and frequency simulation results show the effectiveness of the proposed control scheme when the vehicle is subject to various critical driving situations.

Design of robust controllers for active vehicle suspension using the mixed μ synthesis

Summary The mixed µ synthesis for active suspension problems is proposed. Applying this method the real parametric uncertainties can be taken into consideration, which is more realistic than the traditional approaches, and the design process yields a less conservative compensator than other robust control design methods. The concept of the active suspension design using full-car models to handle the uncertain components is presented. The result of the mixed µ method is compared with the complex µ synthesis, and the passive system.

Robust Control and Linear Parameter Varying approaches: Application to Vehicle Dynamics

The main objective of the book is to demonstrate the value of this approach for controlling the dynamic behavior of vehicles. After some theoretical background and a view on some recent works on LPV approaches (for modelling, analysis, control, observation and diagnosis), themain emphasis is put on road vehicles but some illustrations are concerned with railway, aerospace and underwater vehicles. It presents, in a firm way, background and new results on LPV methods and their application to vehicle dynamics. The content of the book is as follows, and it is divided in 3 parts. In the first part some backgrounds on LPV systems are presented.Marco Lovera introduces first the concept of LPV systems in Chapter 1. Jozsef Bokor and Zoltan Szabo then presents in Chapter 2 some important features of the geometric approach for LPV systems analysis, and in Chapter 3, they introduce a specific class of LPV systems, namely the bimodal switching systems, where the switch from one mode to the other one depends on the state (closed-loop switching). In Chapter 4, Didier Henrion presents some recent results on LPV systems with positive polynomial matrices. Chapter 5, from Meriem Halimi, Gilles Millerioux and Jamal Daafouz, is dedicated to polytopic observers for LPV discrete-time systems. Chapter 6 tackles the fault diagnosis issue, and David Henry introduces the Fault Detection and Isolation LPV filters with some aerospace application. The second part concerns the application of LPV methods to road vehicles. First Anh-Lam Do, Charles Poussot-Vassal, Olivier Sename and Luc Dugard present some LPV control approaches in view of comfort improvement of automotive suspensions equipped with MR dampers.In Chapter 8 Peter Gaspar proposes some design methods of integrated control (of suspension, braking and steering actuators) for road vehicles. In Chapter 9, a coordinated control of braking/steering actuators through LPV technics is proposed by Charles Poussot-Vassal, Olivier Sename, Soheib Fergani, Moustapha Doumiati and Luc Dugard. In Chapter 10, John J. Martinez and Sebastien Varrier present some new results on Multisensor Fault-Tolerant Automotive Control in the LPV framework. In Chapter 11, some theory and application to braking control of the Virtual Reference Feedback Tuning approach for LPV systems, are presented by Simone Formentin, Giulio Panzani and Sergio M. Savaresi. This part is concluded by Peter Gaspar and Zoltan Szabo in Chapter 12, with the design of a hierarchical LPV controller of an active suspension system for a full-car vehicle. The third and final part is an opening to other vehicles such as railway, aerospace and underwater applications, for which the LPV approaches can be very attractive. First Peter Gaspar and Zoltan Szabo present in Chapter 13 an observer-based brake control for railways. Then Jean-Marc Biannic gives, in Chapter 14, a large overview of LPV control strategies for aerospace applications. Finally Chapter 15 by Emilie Roche, Olivier Sename and Daniel Simon, concludes the book with the design of LPV controllers with varying sampling for the altitude control of an AUV (Autonomous Underwater Vehicle), where depth measurements are asynchronously supplied by acoustic sensors. We also would like to mention that this book is also part of the results of the 3- years bilateral collaboration project between the CNRS and the HungarianAcademy of Sciences: Robust and fault tolerant multivariable control for Automotive Vehicle. We would like to thank all the contributors for providing very nice and high level chapters in this book. We hope that this book will interest various researchers and graduate students in control of vehicle dynamics as wall as in robust control and LPV systems.

Active suspension design using linear parameter varying control

In this paper, the linear parameter-varying (LPV) method is applied to the modelling and control of the active suspension system of vehicles. Besides the nonlinear characteristics of the suspensions, in the construction of the LPV model both the performance requirements and the model uncertainties are taken into consideration. The trade-off between the performance demands is guaranteed by using parameter dependent gains. The synthesis and the analysis of the LPV based robust control design is performed. Finally, the method is demonstrated in a quarter-car model.

Robust LPV– ∞ control for active suspensions with performance adaptation in view of global chassis control

This paper presents a new methodology for suspension control in view of global chassis control, developed in particular to guarantee greater driving safety and comfort. The control of the suspension subsystem allows the vehicle road holding (safety) and passenger comfort to be improved, but not at the same time. In order to reach them for every driving situation, an ‘adaptive’ two-degrees-of-freedom controller for active suspensions is proposed. This control architecture is ‘open’ and could be linked and aggregated to many other controllers of vehicle dynamics. This control strategy ensures, on the one hand, the robustness in performances with respect to parameter uncertainties and, on the other hand, the trade-off between road holding and comfort. The proposed design is based on the LPV/ ∞ theory. Robust stability and performances are analysed within the μ-analysis framework.

The Design of a Combined Control Structure to Prevent the Rollover of Heavy Vehicles

In this paper a combined control structure to decrease the rollover risk of heavy vehicles is developed. In this structure active anti-roll bars are combined with an active brake control. Selecting the forward velocity and the lateral load transfer at the rear as scheduling parameters, a linear parameter varying model is constructed. In the control design the changes in the forward velocity, the performance specifications and the model uncertainties are taken into consideration. The control mechanism is demonstrated in various maneuver situations.

The Design of an Integrated Control System in Heavy Vehicles Based on an LPV Method

In this paper an integrated control structure with individual active control mechanisms, i.e. active anti-roll bars, active suspensions, and an active brake mechanism, is proposed. Its purpose is to improve rollover prevention, passenger comfort, road holding and guarantee the suspension working space. In the control design the performance specifications both for rollover and suspension problems, and the model uncertainties are taken into consideration. In the weighting strategy of control design fault information is also taken into consideration. The design of the control system is based on an H∞Linear Parameter Varying (LPV) method. To enhance the performance of the controlled system, the control mechanism is extended with a prediction procedure, in which an observer-based prediction algorithm is proposed.

Towards global chassis control by integrating the brake and suspension systems

Abstract A control structure that integrates active suspensions and an active brake is proposed to improve the safety of vehicles. The design is based on an ℋ∞ control synthesis extended to LPV systems and uses a parameter dependent Lyapunov function. In an emergency, such as an imminent rollover, the safety requirement overwrites the passenger comfort demand by tuning the performance weighting functions associated with the suspension systems. If the emergency persists active braking is applied to reduce the effects of the lateral load transfers and thus the rollover risk. The solution is facilitated by using the actual values of the so-called normalized lateral load transfer as a scheduling variable of the integrated control design. The applicability of the method is demonstrated through a complex simulation example containing vehicle maneuvers.

Control of an experimental mini quad-rotor UAV

The design and the initial realization of control on an experimental in-door unmanned autonomous quadrotor helicopter is presented. This is a hierarchical embedded model-based control scheme that is built upon the concept of back-stepping, and is applied on an electric motor-driven quadrotor UAV hardware that is equipped with an embedded on-board computer, inertial sensor unit, as well as facilities that make it suitable to be involved in an in-door positioning system, and wireless digital communication network. This realization forms an important step in the development process of a more advanced realization of an UAV suitable for practical applications; it aims clarification of the control principles, acquiring experience in solving control tasks, and getting skills for the development of further realizations.

Design of Active Suspension System in the Presence of Physical Parametric Uncertainties

The purpose of the paper is to study the design of the active wheel suspension system. The goal of the control design is the disturbance attenuation with respect to the road disturbances when some of the physical parameters of the system are uncertain. On the basis of a linear quarter-car model the tire stiffness and suspension stiffness are assummed to be uncertain. In this paper the authors deal with some new robust design methods. They examine the applicability of H¿ control in case of the active suspension system using a quarter-car model. The problem is solved as a direct state-feedback H¿ control problem and in case of structured uncertainties as an RLQR (Robust LQR) design task. On the basis of combination of these two methods new procedure is proposed.