A microcomputer performs roll control and communication control. In roll control, when the steering state detecting means and vehicle velocity detecting means detect a factor which causes a roll state of the vehicle body, a second control signal is produced to open desired supply and exhaust control valve so as to supply a preset amount of fluid to the fluid spring chambers of contracted suspension units and to exhaust a preset amount of fluid from the fluid spring chambers of stretched suspension units. In communication control, a first control signal is supplied to the communicating means to open the communication control valve when the steering state sensor detects that the steering angle falls within a preset steering angle and to close the communication control valve otherwise. After generation of the first control signal, when the steering state sensor detects that the steering direction of the steering wheel is in a return direction toward the neutral position and the steering angular velocity is lower than a preset steering angular velocity, a third control signal is supplied to the communicating means so as to open the communication control valve. When the steering state sensor detects, a third preset time after a second preset time from the generation of the third control signal, that the steering angle has reached the preset neutral range, a fourth control signal is produced to close the communication control valve for a fourth preset time.

Wheel suspension units each having fluid spring chambers are arranged in a vehicle suspension apparatus. A roll control quantity determined in accordance with the relationship between a vehicle velocity and a steering angular velocity, i.e., inlet solenoid valves and exhaust solenoid valves, are controlled in accordance with a solenoid ON/OFF time, thereby controlling the roll of a vehicle.

An effective vehicle attitude control method in which the abrupt change of the vehicle attitude due to the acceleration slip control can be quickly controlled. When the slippage of a drive wheel is determined to be greater than a predetermined value, the drive force of the drive wheel is controlled and, at the same time, the suspension characteristic is altered to a harder state. For preferentially keeping maneuverability and riding comfort, the altered suspension characteristic may be restored to the original state when a preset time period has passed.

An anti-rolling motion control system for an automotive vehicle is provided. This control system comprises shock absorbers each being variable of a damping coefficient within a range from softer to harder damping characteristics, a steering sensor for monitoring a steered angle of a steering wheel, and a rolling motion control unit. The rolling motion control unit is operable to derive steered angular velocity based on the steered angle of the steering wheel. The rolling motion control unit controls the shock absorbers so that the damping coefficients are modified to exhibit the harder damping characteristics when the steered angular velocity and the steered angle are greater than preselected first and second threshold values respectively for suppressing rolling motion of a vehicle body effectively while securing traveling stability.

A control system for an adjustable automotive vehicle suspension unit calculates the instantaneous angular rate of a steering handwheel associated with the vehicle and compares the calculated rate with an initiation value. If the calculated angular rate exceeds the initiation value, the excursion angle of the steering handwheel will be measured during a predetermined time period and in the event that such excursion angle exceeds a critical value during the time period or a threshold value at the conclusion of the time period, the adjustable suspension unit will be adjusted accordingly.