RIDE COMFORT IMPROVEMENT IN POST-BRAKING PHASE USING ACTIVE SUSPENSION

Frequent acceleration and deceleration of vehicle especially in urban traffic arouse relative frequent pitch motion accordingly. As the orientation of vehicle acceleration alters, the inertia of human body and the pitch motion transferred by the suspension cause passengers' body to swing back and forth, thus leading to ride discomfort, even motion sickness. In particular, such ride discomfort is noticeable in the post-braking phase, resulting from the subsequent rebound of the vehicle body after complete stop, according to the subjective experiment in this paper. The suspension characteristics are dominant in the pitch motion of post-braking phase. This paper applies an active suspension based on LQR controller to attenuate the negative rebound effect. Considering the trade-off between rebound time and rebound impact, a LQR optimal controller is proposed to control the active suspension, minimizing the negative pitch motion and improving the braking ride comfort. The simulation result indicates that the vehicle rebound in the post-braking phase is conspicuous around the resonant frequency of the vehicle body. Furthermore, the magnitude of frequency response at this critical area has been decreased and the ride comfort in post-braking phase has been improved with the proposed LQR controller.