Active control of an automobile suspension system for reduction of vibration and noise

Abstract

A new method for controlling road noise transmitted through the suspension system of an automobile was developed, using a Lincoln LS automobile as the target vehicle. In this vehicle, road surface roughness generates vibrations that are transmitted into the automobile primary through a single bushing (the "point 4 bushing") on each of the front suspension control arms. An electromagnetic actuator was designed, built, and tested on a Lincoln LS with simulated roads noise. The actuator applies a force across the point 4 bushing, in response to accelerations of the vehicle frame, just inboard of the bushing, with the goal of reducing the net forces transmitted into the vehicle frame, which ultimately produce unwanted interior noise. Several tonal controllers were developed, each designed to operate in a narrow frequency band, and to eliminate the cross member (frame) vibration just inside the point 4 bushing. The tonal controllers were able to eliminate cross member vibration at the desired frequency. Eliminating the cross member vibration resulted in modest reductions interior sound levels. A successful vibration control system (in this vehicle) would need to eliminate cross member vibrations over frequency range 100 to 200 Hz. However, a broadband controller with this electromagnetic actuator system proved to be difficult, due to undesirable non-minimum phase dynamics.