Fuzzy logic controller for active suspension systems of intelligent vehicles

The use of various types of active suspensions is spreading more and more and these systems, in addition to the "classic" functions guaranteed by a simple passive suspension system, are able to generate an internal force F(t) variable in time between the vehicle body and the wheel. This force, appropriately modulated over time, helps stabilize car response and achieve better performance than simple passive suspension. In order to modulate this force through a feedback control, one of the most used controllers is the standard PID (Proportional Integrative Derivative). In this work, it is analysed if it is possible to further optimize the operation of this PID controller by using the fuzzy logic to adapt the characteristic values of the controller instant by instant. To this aim, a suspension system of a quarter-car vehicle model is implemented and analysed in different configurations with various suspension systems (passive, skyhook, active with a PID controller and active with a fuzzy PID controller). A qualitative and quantitative analysis of each case will be presented providing evidence of the better performance of a suspension system equipped with a controller optimized according to the fuzzy logic.