SEMI-ACTIVE CONTROL AND OPTIMUM PREVIEW CONTROL APPLICATIONS TO VEHICLE SUSPENSION

Optimum active control is theoretically analyzed for a vehicle suspension model using optimum control theory. In addition, a semi-active control system is proposed which approximates optimum active control using a conventional coil spring and controllable damper. System performance is evaluated by computer simulation. Compared to a passive system, optimum active control can reduce the vertical acceleration root mean square value of a sprung mass by about 18%. Moreover, the semi-active control system developed here can achieve nearly the same performance as the optimum active control system. Additionally, optimum preview control is theoretically analyzed for vehicle models with 2 and 4 degrees of freedom. A sensor which detects the approaching road profile is used to control vehicle vibration. The performance of this system is evaluated and compared with a passive system. It can reduce the vertical acceleration rms value by about 55%, and the rms value for pitching angular acceleration by about 65%.