AUTOMOTIVE SUSPENSION CONTROL SYSTEM WITH ROAD-CONDITION-DEPENDENT DAMPING CHARACTERISTICS

摘要

A suspension control system for an automotive vehicle automatically adjusts the damping strength of variable shock absorbers or other dampers in accordance with road surface conditions as recognized by frequency analysis of a vehicle height or vibration sensor signal. The sensor signal reflects vertical displacement of the vehicle body from the road surface and includes high-frequency components due solely to displacement of the wheels or unsprung mass relative to the road surface and low-frequency components due to displacement of the vehicle body or sprung mass. The sensor signal is filtered into these separate frequency bands and the amplitude of each is compared to a corresponding reference level to give an indication of the irregularities in the road surface. Specifically, a high-amplitude low-frequency component indicates large-scale bumps and dips capable of bouncing the vehicle whereas a strong high-frequency component reflects a rough-textured road surface, such as gravel. The comparison information is sent to a suspension system controller which causes actuation of the shock absorbers to a hard mode of operation when the low-frequency sensor signal components are relatively strong.