Abstract: Vehicular acceleration is sensed and used to set and/or modify at least two of a plurality of control sensitivity values in a manner which increases one with respect to the other and thus avoids the situation wherein a limited amount of servo power is wasted by futile operation of a servo powered arrangement which cannot produce a large control effect under the instant operating conditions and enables an adequate amount servo power to be directed to the operation of a different arrangement which can be effective.

Abstract: In a vehicle vibration damping force control system, rolling, pitching and bouncing motions are detected independently in a predetermined priority order; each detected motion is compared with respective predetermined levels; if each detected motion exceeds each predetermined level, hydraulic switch valves are controlled so that operating fluid energized by stroke changes of the hydraulic cylinders due to the detected vibration motion is passed through damping force generating mechanisms to increase a damping force against only the detected vibration motion, without generating any other damping forces against other non-detected vibration motions. Since only the necessary damping force is generated against only the detected vibration motion, the damping force is minimized to maintain vehicle riding comfort.

Abstract: A damping device is installed between a vehicle body and desired two of wheels and provided with a damping force producing mechanism for producing a larger damping force when the two wheels make strokes involving a relative movement therebetween, such as at the time of rolling, pitching, etc. than when the two wheels make strokes without involving any substantial relative movement therebetween, such as at the time of bouncing. In one embodiment, the damping force producing mechanism comprises a pair of restrictions in communication with cross conduits interconnecting upper and lower cylinder chambers. The conduits and cylinder chambers are arranged so as to cause a larger flow rate of fluid to pass through the restrictions when the wheel strokes involve a relative movement between the wheels than when the wheel strokes does not involve such relative movement.

Abstract: A suspension control system for automotive vehicles 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, the amplitude of each of which is compared to a corresponding reference level.

Abstract: A suspension control system includes a mechanism for monitoring wheel slippage on each of individual wheels as a parameter represenatative of road/tire traction. Suspension control is performed generally according to the vehicle driving conditions reflected in various suspension control parameters, such as vehicular speed, lateral acceleration and so forth in order to adjust spring coefficient or damping characteristics of a suspension system which is provided between a vehicle body and a suspension member supporting each individual wheel in order to adjust wheel load distribution and whereby to minimize variation of vehicular attitude change. Suspension control is further performed with taking the road/tire friction as one of suspension control parameters in order to provide traction dependent wheel load distribution.

Abstract: A suspension control system for automotive vehicles 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, the amplitude of each of which is compared to a corresponding reference level.

Abstract: A vehicle steering system includes a front hydraulic actuator for steering front wheels, a rear hydraulic actuator for steering rear wheels, a front control valve of an open center type for controlling the fluid pressure of the front actuator, a rear control valve of the open center type for controlling the fluid pressure of the rear actuator, a common fluid pressure source, and a flow dividing valve for dividing a fluid flow from the common pressure source into two flows directed to the front and rear control valves so that the front and rear control valves of the open center type can control the fluid pressures independently and accurately.

Abstract: A steering control system for a vehicle includes an actuator for steering rear wheels in response to a control signal, a steering angle sensor, a vehicle speed sensor, and controller for controlling a rear wheel steer angle by producing the control signal according to the following transfer function; ##EQU1## where a.sub.0, a.sub.1, a.sub.2, a.sub.3, a.sub.4 and a.sub.5 are parameters whose values are determined by the vehicle speed, vehicle constants determined by the specification of the vehicle, and desired constants representing a preset desired steering characteristic.

Abstract: A power drift control device produces a yaw moment in the direction of causing oversteer on the basis of acceleration and steering wheel angle during cornering of a vehicle. The yaw moment is variable depending upon variation of acceleration at a rate which increases as a steering wheel angle increases.

Abstract: A method of steering a vehicle having a set of steerable front wheels and a set of steerable rear wheels. The front and rear wheels are both secondarily steered in addition to a main steer of the front wheels caused by an operation of a front wheel steering gear in response to an operation of a steering wheel. The method comprises providing to the front wheels a secondary steer angle corresponding to at least a differentiated value of a steer angle of a steering wheel in such a way as to increase an overall steer angle of the front wheels and providing to the rear wheels a secondary steer angle proportional to the steer angle of the steering wheel and in the same direction as the steer angle of the front wheels.

Abstract: A suspension control system for automotive vehicles 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 of 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, the amplitude of each of which is compared to a corresponding reference level.

Abstract: In order to imprive the accuracy of the time derivative of a steering angle signal consisting of discrete measured values, a vehicle steering control system for producing a steering angle control signal from the steering angle, the time derivative of the steering angle and other data is provided with a controller having a averaging section for periodically determining an average of a predetermined number of the measured values of the steering angle, and a differentiating section for determining the time derivative of the steering angle by using the averages determined by the averaging section, instead of directly using the steering angle signal.

Abstract: A fail-safe steer angle control system includes a front auxiliary steering actuator for controlling a front wheel steering angle in response to a front control signal representing a front wheel auxiliary steering angle, a rear wheel steering actuator for controlling a rear wheel steering angle in response to a rear control signal, a steering angle sensor for sensing the steering wheel angle, and a controller which produces the front control signal based on the steering wheel angle in accordance with a predetermined first relationship, and produces the rear control signal based on the steering wheel angle in accordance with a predetermined second relationship. The controller has a fail-safe section which adjusts the first or second relationship when an abnormal condition is detected in either the front steering system or the rear steering system.

Abstract: A steering control system comprises means for performing a secondary steer of front and rear wheels by angles computed using a steer angle .theta., steer angle angular velocity .theta. and vehicle speed V from the following formulas, ##EQU1## where .delta.f is a front wheel secondary steer angle, .delta.r is a rear wheel secondary steer angle, N is a steer gear ratio and Kf, Kr, Tf and Tr are control constants which are functions of vehicle speed.

Abstract: A rear wheel steering control system for a four wheel steerable vehicle has a controller such as a microcomputer for steering rear wheels through a hydraulic actuator. When a small turning radius is required, the controller steers the rear wheels in an opposite direction to a direction in which the front wheels are steered. The control system further has various sensors such as front wheel angle sensor, rear wheel angle sensor, vehicle speed sensor and gear position sensor for sensing a position of a transmission. From one or more of the sensor output signals, the controller determines whether the vehicle is in a predetermined condition in which the rear wheel steering action in the opposite direction should be restrained in order to prevent the rear end of the vehicle from swinging laterally in the opposite direction and bumping against an adjacent object. If it is determined that the vehicle is in the predetermined condition, the controller steers the rear wheels gradually in the opposite direction.

Abstract: 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.

Abstract: A suspension control system has a manual operator which is manually accessible is provided for adjusting suspension control characteristics depending upon the driver's tastes or depending upon the vehicle condition. The adjustment of the suspension control characteristics can take place with respect to each of a plurality of suspension control items, such as roll-suppressive suspension control, anti-dive suspension control, anti-scout suspension control, road roughness dependent suspension control, bottoming control and so forth. By allowing adjustment of the suspension control characteristics with respect to each control item independently of that with respect to other control items, the suspension control characteristics of the overall suspension control system can be precisely fit the driver's feeling and/or precisely adapted to the vehicle condition.

Abstract: A suspension control system can precisely control the damping characteristics of vehicular suspension for successfully and satisfactorily providing anti-dive and anti-rebound feature. The suspension control system is adapted to detect vehicle deceleration on the basis of a variation of a vehicle speed and to compare the vehicle speed with a predetermined vehicle speed criteria across which damping characteristics of the vehicular suspension vary between a harder suspension mode and a softer suspension mode. The vehicle speed criteria is variable depending upon vehicle deceleration so that the criteria becomes higher when the magnitude of deceleration is greater than a predetermined level. By hardening the suspension at an earlier timing during relatively abrupt deceleration of the vehicle, the magnitude of nose dive is reduced and the magnitude of rebounding motion after nose-dive can be reduced. This assures riding comfort by reducing the magnitude of pitching behavior of the vehicle front end.

Abstract: A suspension control system is able to precisely adapt damping characteristics to the road condition, even when the vehicle passes over bump, manhole, hole and so forth. The suspension control system includes a road sensor which produces a road condition indicative signal. A controller is adapted to recognize bump, manhole, hole and so forth which causes temporary bounding and rebounding motion for the vehicle, on the basis of the road condition indicative signal from the road sensor. The controller produces a control signal to harden damping characteristics of suspension when bump, manhole, hole and so forth is detected with a given delay time. The delay time for changing damping characteristics is different at the front and rear suspension from each other so that each of the front and rear suspension can be stiffened at a good timing.

Abstract: An automotive vehicle suspension having a damper with variable damping characteristics, specifically, an adjustable damping force. A controller responds to an application and release of the vehicle brakes by increasing the damping force, to suppress nose-dive of the vehicle at the beginning of braking and to suppress pitching motion of the vehicle at the end of braking.