Linear quadratic regulator and skyhook application in semiactive MR damper full car model

Abstract

The use of magnetorheological (MR) dampers on a semiactive vehicle suspension system results in a less satisfactory performance than fully-active suspensions due to the limited input range and approximate controllers for MR damper-based suspension system. Many existing schemes for MR damper control use linear quadratic recursive methods to optimize the control input without considering the full car model and the MR damper characteristics. Skyhook control scheme has shown good performance in quarter car models than the optimized linear quadratic recursive controllers but has not been used very much in conjunction with a full car model. In this paper, by designing a controller that incorporates the skyhook control with an optimized linear quadratic control scheme based on a full car model, the MR dampers can improve the ride comfort by reducing the displacement of the chassis with reduced steady-state time required for vibration damping. This is because, the full car model does not only consider the motion of the chassis along the vertical direction, but also the attitude disturbances in the suspension system controller design. The significance of considering the attitude disturbances is that the suspension can efficiently damp the disturbances coupled by the four wheels to reduce its effects at the center of gravity. The cost function used constitutes the energy of the suspension and the disturbance input. By optimizing the cost function, the total energy is restrained to the minimization of the suspension energy resulting into a more comfortable ride. The cost function is used as a yard stick to evaluate the ride comfort of the system. A centralized controller complements the need for a controller for each damper with improvement in system dynamics.