A model-free control structure for the on-line tuning of the semi-active suspension of a passenger car

Comfort and road handling of a passenger car can be improved by replacing its passive suspension by a controlled semi-active suspension. The selection of an appropriate control structure is crucial, since it determines the complexity of the control design and parameter tuning process.This paper presents a flexible and transparent model-free control structure based on (1) physical insights in the car and semi-active suspension dynamics used to linearise and decouple the system, and (2) decentralised linear feedback. The resulting controller can be tuned on-line intuitively using a limited number of physically interpretable parameters.The simplicity of the control structure and the absence of any model of either the car or the shock absorber yields that the code of the controller can run on a low-cost DSP with a minimum amount of memory. The evaluation of experienced test-pilots states that the car with tuned controller behaves naturally, yields comfortable ride on a wide variety of calibrated evaluation tracks and yet is well controlled during all handling manoeuvres.