System for controlling active suspensions of a vehicle

Abstract

In a system for controlling active suspensions of a motor vehicle, having fluid suspensions for the respective wheels, a longitudinal acceleration sensor, control valves for the respective suspensions, and a controller for adjusting the control valves to charge and discharge a fluid into and out of the fluid suspensions so as to control the vehicle attitude, a hysteresis circuit is provided to receive a longitudinal acceleration signal from the acceleration sensor, for hysteresis processing of the signal, whereby microvibration components included in the acceleration signal is removed. The width of hysteresis is increased as the vehicle speed increases because the amplitude of microvibration becomes larger as the vehicle speed increases. For more stable vehicle attitude control, a dead-zone circuit is provided to cut fluctuations of the hysteresis-processed signal within a specific width in the vicinity of zero.