Active Fuzzy Control of Linear and Nonlinear Suspensions in Vehicles

Suspensions are vital for a vehicle, since they provide safety and comfort. There are many types of suspensions in the industry. The most advanced of them are the active or electronic suspensions, where the degree of damping is modified in order to achieve the desired rolling of the vehicle. This is achieved by changing the pressure or the flow of air or oil inside the damper, or its properties. A control system is necessary for this task. Powerful and robust soft control tools, such as fuzzy inference systems can provide the desired results. In the present paper, the active suspension is controlled by a fuzzy logic controller through a piezoelectric actuator which provides the control force. Classical control tools, such as the Proportional-Integral-Derivative (PID) controller are used for comparison. From the simulation results it is shown that both methods can achieve smooth behaviour of the active suspension. Fuzzy control was proved to be faster than the PID, while the latter was more efficient in the first period of vibration. Moreover, the fuzzy controller was proved very efficient even in the presence of non-linearities within the suspension system.