Vibration control of seat suspension using H_∞ reliable control

This paper is concerned with the problem of robust H_∞ reliable load-dependent control design for a class of semi-active seat suspension systems. A four degree-of-freedom human body model is considered in order to investigate the control strategy more precisely. It is assumed that the human body mass resides in an interval and can be measured online. The load-dependent approach is based on a parameter-dependent Lyapunov function. Thus the proposed method is capable of reducing the conservatism and improving the closed-loop performance. Actuator faults are also considered in the controller design process and the resulting control systems are reliable because they provide guaranteed asymptotic stability and H_∞ performance in spite of the possible actuator failures. The usefulness and advantages of the controller design methodology are demonstrated through a design example.