A self-organizing fuzzy controller for an active suspension system

A quarter-car hydraulic suspension system has been constructed to evaluate the performance of active vehicle suspension. Since this hydraulic actuating suspension system has a nonlinear and complicated mathematical model, it is difficult to design a model-based controller. Hence, a self-organizing fuzzy controller (SOFC) is employed to control the position and acceleration oscillation amplitudes of the sprung mass due to the rough road variation. This approach has learning ability for responding to the time-varying characteristic of the oscillation coming from the tire. Its control rule bank can be established and modified continuously by on-line learning. E-modification and dead-zone concepts are introduced into the SOFC fuzzy adaptation rule to improve the oscillation feature of control law and the gradual divergence problem. The experimental results show that this intelligent controller effectively suppresses the vibration amplitude and reduces the acceleration of the sprung mass correlating to the road variation for improving the vehicle ride comfort.