Vehicle Body Attitude Control Using an Electronically Controlled Active Suspension

In this paper, the vehicle body attitude in response to low frequency dynamic loads experienced during braking, accelerating, cornering, aerodynamics or payload variations can be controlled using an electronically controlled active suspension. Using a four degree of freedom half vehicle model, a composite controller which consists of Linear Quadratic Regulator vibration controller (LQR) plus Proportional-Integral-Derivative controller (PID) has been designed to isolate the body vibration from the road surface irregularities and maintain the body static height constant as well as control the body pitch motion. Vertical step inputs and different longitudinal step braking forces were applied to the body C.G. to simulate the payload variations and emergency braking effects. The results with the proposed controller showed that the suspension steady state deflection due payload variation was completely removed and the body pitching motion due to the longitudinal inertia forces was substantially reduced in the steady state with high attenuation of the transient response.