A New Control Strategy for Vehicle Active Suspension System Using PID and Fuzzy Logic Control

Since the nonlinearity which inherently exists in vehicle system need to be considered in active suspension control law design, a new control strategy is proposed for active vehicle suspension systems by using a combined control scheme, i.e., respectively using a PID controller and a fuzzy logic controller in two loops. In this paper, the investigation is mainly focused on vehicle ride comfort performance and simulations in straight running operating condition are presented. The control goal is to minimize vehicle body vertical and pitch accelerations for passenger comfort. The control system consists of two parallel control loops. One loop, using PID control, is to minimize vehicle body vertical acceleration; and the fuzzy logic controller is to minimize pitch acceleration and meanwhile to attenuate vehicle body vertical acceleration further by tuning weighting factors. Based on a four degree-of-freedom nonlinear vehicle model, the algorithm is implemented and simulations are carried out in different road disturbance input conditions. Simulation results show that the control strategy is very effective in reducing peak values of vehicle body accelerations, especially within the most sensitive frequency range of human response and also with good stability even if the system is subject to a discrete event input, i.e., a sudden change of road conditions, such as a pothole, an obstacle or a step input. Compared with conventional passive suspensions and an active vehicle suspension by using a linear and fuzzy logic controls, the new designed control system can improve vehicle ride comfort performance significantly and offer better system robustness.