ON THE PERFORMANCE LIMITATIONS OF QUARTER-CAR ACTIVE SUSPENSION MODELS 1

In this paper, constraints on the road disturbance transfer functions are derived for a quarter-car active suspension system. The derived constraints complement the existing constraints in the literature. By using the factorization approach to feedback stability, it is also shown that tire damping couples the motions of the sprung and unsprung masses; and eliminates a wheelhop constraint. The influence of tire damping on the design of an active suspension system for a quarter-car model by the LQG method is illustrated.