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

In 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 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 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 roadholding improvements of this control strategy that will be tested by SOBEN on a testing car in the near future.