H^∞制御理論に基づくアクティブサスペンションの制御

1/4モデルに対する状態フィードバック制御

抄録

In this paper, we consider a quater-car model with a hydraulic active suspension system which has been constructed as a test bed with real size, and propose a new design method of this model based on H^∞ control theory. Our main objective is to realize better ride comfort, in other words, to attenuate the gain of the closed-loop transfer function from the vertical road displacement to the vertical acceleration of the body over the frequency range of human body resonance (3-8Hz) without reducing the wheel-to-road contact which is important for safety and drivability. This design object is handled easily as a loop shaping in the frequency domain, and H^∞ control gives an appropriate framework for carrying out the systematic loop shaping.
As all states in our equipment can be observable directly, we can design a state feedback regulator as one of H^∞ controllers which satisfy the H^∞ norm condition of the closed-loop transfer function from the disturbance to the loop-shaped output.
As the results in some experiments and simulations, we have confirmed the loop-shaping effect such that the body accelaration gain performance of the closed-loop system is significantly attenuated over the range of human resonance compared with that of the open-loop system. And we have also confirmed that the loop shaping is effective for the improvement of the robustness against the change of the body mass and the valve coefficient.