Performance improvement of low bandwidth active suspension system by road disturbance preview control

Abstract

ride comfort and road holding characteristics. Active systems provide superior performance but with a relatively high energy consumption. On the other hand, semi-active systems suffer from passivity constraint, thus the control performance is limited. In general, all introduced systems in the market have limited actuator bandwidth which deteriorates the theoretical performance of the suspension. A feasible enhancement to this problem is to preview the future road disturbances via a look ahead sensor and improve the performance with feedforward control. In practice, active suspension control strategy is continuously adapting its objective between comfort and safety according to the driving conditions. Preview control could enhance both objectives, so the purpose of this study is to give more insights to how preview control can improve the performance in each case and how the feedforward control path should be designed for. For this purpose, two cases will be proposed. The first is to design a controller more oriented to comfort and the other is to design the controller more biased to safety, both without exceeding the suspension deflection constraints. The optimal preview control problem is introduced, and controllers of the two cases has been assessed for different road grades. The results show an improvement in ride comfort, in all cases, but a slight to none in the case of trying to enhance the road holding characteristics.

Modern active chassis control systems have enabled the implementation of a wide range of functions which support and enhance the driver’s ability to pilot the vehicle. One of the key chassis components is the suspension system, which plays the central role in linking the road and the vehicle body. They contribute (with the tires) to the most of the driving feeling of the vehicle. Controlled suspensions offer great improvements in the main dynamic suspension functions