Parameter-dependent input-delayed control of uncertain vehicle suspensions

This paper presents a parameter-dependent controller design approach for vehicle active suspensions to deal with changes in vehicle inertial properties and existence of actuator time delays. By defining a parameter-dependent Lyapunov functional, matrix inequality conditions with reduced conservatism are obtained for the design of controllers. Feasible solutions can be obtained by solving a finite number of linear matrix inequalities (LMIs) embedded within a genetic algorithm (GA). Both state feedback and static output feedback controllers can be designed under a unified framework. Based on the measurement or estimation of the vehicle inertial parameters, a parameter-dependent controller could be implemented in practice. The presented approach is applied to a two-degree-of-freedom quarter-car suspension model. Numerical simulations on both bump and random road responses show that the designed parameter-dependent controllers can achieve good active suspension performance regardless of the variation on the sprung mass and the presence of actuator time delay.