The requirements of ride comfort and driving performance are major development objectives of modern vehicles to satisfy the expectations of customers. It is well known that the suspension system is important to the ride comfort and driving capability. Hence, a semi-active suspension system has been proposed to improve the ride comfort. The paper compares the performance of three control laws for a semi-active suspension system, based on simulated results obtained from a quarter car model. The semi-active damper is modelled as a continuously variable device with maximum and minimum limits and a time delay between the demand and actual forces. The three control laws are based on (a) Full state feedback, (b) limited state feedback and (c) sky hook damping. The results showed that Semi-active suspension system with full state feedback control force gives a better improvement in terms of ride comfort compared with a semi-active with limited state feedback and sky hook control force. Also, semi-active suspension with each previous control force gives a significant improvement in terms of ride comfort compared with a passive suspension system. The mean power dissipation in the semi-active with three control laws and passive suspension systems relative to the rolling resistance power losses are ranged between 14-19%. |
