The adaptation of the active control technology to practical suspension systems of vehicles has remarkably improved the safety and ride-comfort of vehicles. This paper presents a study on the practical realization methods of an active suspension system that combines high response and low energy dissipation. The effects of active control on the stability of vehicle motion and ride-comfort were investigated by practical tests using an experimental vehicle.
The integrated active suspension system consists of a motor-controlled oil pump, which is active power source, and a motor-controlled variable orifice, which is semi-active adjustable element. Multi-controller computer systems for individual controls of each suspension unit and an integrated control of the whole body behavior are also installed.
The control of this system is based on a feed-forward strategy to control handling maneuvers, and a feedback control strategy using the changes in state variables to control the response to road input disturbances. The design objective is to minimize the values of the performance index representing vehicle attitude and ride-comfort.
Experimental results are obtained from the controlled experimental vehicle. The effectiveness of the system is verified by the measurements of the body behavior during handling maneuvers, and of the vibration characteristics during running on various roads. Compared with a non-controlled vehicle, the roll angle of the experimental vehicle caused by steering is decreased by over 50%, and the ride-comfort characteristics is fairly improved in the frequency range below one to several Hertz.