Modélisation et commande de suspensions semi-actives SOBEN

This thesis deals with the modeling, control and estimation of semi-active automotive suspensions in an industrial framework. The main contribution is a complete observer and controller design methodology suitable for semi-active suspensions control. Based on an observer, a main controller, and four local controllers, the proposed strategy allows optimize the comfort and road-holding of the vehicle. The Hinfinity synthesis method, applied to Linear Parameter Varying (LPV) systems is used for the damper control, allowing to take their nonlinearities into account in the synthesis. Various experimental and simulation results are given both for the observer, and for the controllers.Les travaux présentés dans cette thèse concernent la modélisation, la commande et l'estimation de suspensions automobiles semi-actives, dans un contexte industriel. La contribution principale concerne le développement d'une méthodologie de synthèse d'observateurs et de contrôleurs adaptés aux suspensions semi-actives. Fondée sur un observateur, un contrôleur principal et quatre contrôleurs locaux, la stratégie de commande permet d'améliorer le confort et la tenue de route du véhicule. La méthode de synthèse Hinfinity appliquée aux systèmes Linéaires à Paramètres Variants (LPV) est utilisée pour la commande des amortisseurs, permettant ainsi de prendre en compte leurs non linéarités dans la synthèse. Différents résultats de simulation et expérimentaux sont présentés pour valider l'observateur et les lois de commande

Experimental results of an Hinfinity-observer for an industrial semi-active suspension

International audienceIn this paper, an Hinfinity-observer to be used in suspension control application is addressed to estimate a quarter car model equipped with an industrial SOBEN damper, using a reduced number of sensors. Vehicle estimation is one the main challenges in suspension control since many control strategies developped in past studies use variables that are nonmeasurable in practice. This observer is designed in the H1 framework in order to minimize the effect of the unknown road disturbance on the estimated states and uses a single, cheap and reliable acceleration sensor mounted on the unsprung mass. The estimated variables are the vertical velocities and positions of the sprung and unsprung masses of the quarter car. Some experiments done on a testing car highlight the performances of the observer. This observer could be used in a suspension control application in order to reduce the number of sensors and the cost of the control system

Hinfinity/LPV observer for an industrial semi-active suspension

International audienceIn this paper, an H1/LPV observer to be used in an automotive suspension control application is proposed. The system considered is a road disturbance affected quarter car equipped with an industrial SOBEN damper. This observer is designed in the H1 framework in order to minimize the effect of the unknown road disturbance on the estimated states. The damper studied in this paper is highly nonlinear, therefore an adaptative linear parameter varying (LPV ) structure is proposed to improve the robustness of the observer. The observer presented here uses a single position sensor and is easy to implement in a real industrial application because of its simple linear structure. Some simulation results highlight the performances of this observer in realistic noise and uncertainty conditions. The estimated state variables of the quarter car model could be used for example in a state feedback control strategy to improve the comfort and roadholding level of a vehicle

A LPV control approach for a semi-active hydraulic damper

International audienceIn this paper, a new control strategy is developed to improve comfort and roadholding of a ground vehicle equipped with an industrial damper. This damper can be controlled by a small servomechanism which adjusts the damping rate. The main controller is a Linear Parameter Varying static state-feedback controller synthesized in the H∞/LPV framework to compute the required damping force that minimizes the movements of the vehicle's body on one hand, and the deflection of the tire on the other hand. A scheduling strategy is developed on the basis of the real damper behavior to improve performances without using active damping forces which would be useless for such a semi-active system. Here the controller takes into account the technological constraints, the damper behavior and is easy to implement in an industrial application. The comfort and roadholding levels of the semi-active suspension are studied using some adapted criteria and compared with the passive suspension. Some simulations emphasize the improvements of this control stategy that will be tested by SOBEN on a testing car in the near future

Semi-active H∞/LPV control for an industrial hydraulic damper

International audienceIn this paper, a new control strategy is developed to improve comfort and roadholding of a ground vehicle equipped with an industrial damper. This damper can be controlled by means of a small servomechanism which adjusts the damping rate. The main controller is a linear parameter varying (LPV ) static state-feedback controller synthesized in the H1/LPV framework to compute the required damping force that minimizes the movements of the vehicle's body on one hand, and the deflection of the tire on the other hand. A scheduling strategy is developed on the basis of the real damper behavior to improve performances without using active damping forces which would be useless for such a semiactive system. Here the controller takes the constraints of the technology and the damper behavior into account and is easy to implement in an industrial application. The control of the servomechanism is provided by a simple PID controller that ensures that the damper provides the required force. The performances are illustrated on an identified nonlinear model of the damper embedded in a quarter car model. The comfort and roadholding level of the semi-active suspension are studied using some adapted criteria and compared with the passive ones. Some simulations emphasize the comfort and oadholding improvements of this control stategy that will be tested by SOBEN on a testing car in the near future

Performance analysis and simulation of a new industrial semi-active damper

International audienceThis paper deals with modeling and control of a semi-active suspension made up with a new industrial semi-active damper, in order to improve comfort and road-holding level of the vehicle. In the past few years, many control strategies have been developed using linear suspension models. A nonlinear model of the industrial damper is developed with physical equations and integrated in a quarter vehicle model. Some tests are done on the real damper in order to validate the model. The comfort and road-holding level of the semi active suspension are studied using some adapted criteria and compared to the passive ones using simulations. These results emphasize the performances improvement resulting from the control of the damper

An LPV Approach for Semi-Active Suspension Control

International audienceIn this paper, a new LPV control approach for semi-active automotive suspension equippedwith aMagneto- Rheological (MR) damper is presented. The interest of the approach is (1) to embed the model of semi-active suspension in a linear system design and (2) to allow limiting the damper force so that the controlled semi-active suspension works within its admissible region. First, a semi-active suspension model of an MR damper is reformulated in the LPV framework, which provides an LPV model for the vertical car behaviour. Then, by using the H1 control approach for polytopic systems, an LPV controller is synthesized to improve the passenger comfort while keeping the road-holding performances. The performances of the LPV controller are analyzed, based on simulations using the embedded nonlinear model of the MR dampe

An LPV Approach for Semi-Active Suspension Control

International audienceIn this paper, a new LPV control approach for semi-active automotive suspension equippedwith aMagneto- Rheological (MR) damper is presented. The interest of the approach is (1) to embed the model of semi-active suspension in a linear system design and (2) to allow limiting the damper force so that the controlled semi-active suspension works within its admissible region. First, a semi-active suspension model of an MR damper is reformulated in the LPV framework, which provides an LPV model for the vertical car behaviour. Then, by using the H1 control approach for polytopic systems, an LPV controller is synthesized to improve the passenger comfort while keeping the road-holding performances. The performances of the LPV controller are analyzed, based on simulations using the embedded nonlinear model of the MR dampe

Hysteresis Modelling for a MR Damper

International audienceAn experimental dataset of a commercial Magneto-Rheological (MR) damper is exploited for identification of a Hysteresis-based Control-Oriented model. The model wellness for hysteresis, saturation and transient responses is shown through validation with experimental data. A study case that includes a Quarter of Vehicle (QoV) shows that the hysteresis phenomena could affect the primary ride and vehicle handling. Several analysis based on open and closed loop simulation demonstrated that hysteresis must be considered for controller design