Robust control of active suspension — Improvement of ride comfort and driving stability using half car model

This paper presents a method of robust control for an active suspension to improve both ride comfort and driving stability. The ride comfort is related to the vertical and pitch vibration of car body. To improve ride comfort more effectively, the loop shaping is used for vertical and pitch motions based on ISO2631-1. On the other hand, the driving stability is evaluated by the fluctuation of vertical force of wheels which is affected by the pitch motion. To consider both of them more realistically, a half car model including vertical and pitch motions are analyzed. For practical application, to consider uncertain parameters is important. This paper focuses on the car body mass. The controller is designed to guarantee the robust stability for the uncertain parameter with polytopic representation. LQ controller, which can consider both performance and input energy, is used. The problem is formulated to solving finite LMIs. The effectiveness of proposed method is evaluated by the experiments.