A novel semi-active control strategy based on the cascade quantitative feedback theory for a vehicle suspension system

Abstract

This paper proposes a robust controller for semi-active suspension system with actuator dynamics using the quantitative feedback theory. It solves the vehicle vibration attenuation problem using the novel cascade approach. The proposed cascade quantitative feedback theory control approach consists of the inner and outer loop. The damping force tracking of the magneto-rheological damper is chosen as the inner loop, while the outer loop is for the vibration attenuation. The inner loop is added to the control structure to enhance damping force tracking capabilities. The damping force of the magneto-rheological damper depends on the many factors, such as the complex and nonlinear (hysteresis) dynamics and operating temperature. The actuator (magneto-rheological damper) dynamics is well approximated by a first-order model with an uncertain time constant which captures the essential dynamics. The simulation case study is conducted on a realistic quarter car suspension system to show the effectiveness of the proposed cascade control method. The proposed method is found to deliver superior performances, in terms of ride comfort and road holding, over the skyhook, H ∞ control, and single-loop quantitative feedback theory control under the bump, sine, and random road disturbances.