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 rear wheel steering angle control system for a 4WS vehicle is provided. This system includes a first circuit for deriving a locus defined by a specific point provided on the front end of the vehicle, a second circuit for deriving a locus defined by a specific point provided on the rear end of the vehicle, a third circuit for providing a target steering angle for the rear wheels so that a rear corner does not overhang outwardly during turning, and a controller for controlling an actual angle for steering the rear wheels. The third circuit determines the target steering angle so as to restrict the magnitude of offset of the rear specific point from the locus of the front specific point. The controller steers the rear wheels by the target steering angle to restrict the magnitude of overhang of the rear end of the vehicle and enables the vehicle to turn within the minimum possible turning circle.

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 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: A system for controlling the steering angle of the rear steerable wheels of a vehicle senses the front wheel steering angle, the vehicle speed and a manually selected mode signal for a new mode of two driving modes. A microcomputer containing models for the two modes determines a target yaw rate for the selected mode from which is calculated a target rear wheel steering angle to control rear wheel steering. However, the system is prevented from calculating a steering angle for the new mode when it would cause an unsafe abrupt change in vehicle behavior as when the rear wheel steering angle is not nearly zero which is equivalent to the sensed front steering angle, the target yaw rate and the lateral acceleration all being nearly zero.

Abstract: A vehicle motion estimating system for estimating a vehicle motion variable such as yaw rate, lateral acceleration, or side slip angle by using a mathematical vehicle model is composed of a digital device such as a microcomputer for digitally solving equations of vehicle motion of a time-varying type such as equations of yawing motion and side slipping motion, and an analog device for solving one or more time-invariant linear differential equation such as an equation of a steering system about a kingpin or an equation of rolling motion.

Abstract: A steer angle control system for a controlled vehicle comprises sensors for sensing the steering wheel angle and the vehicle speed of the controlled vehicle, a processor such as a microcomputer, and an actuator for steering the front and/or rear wheels of the controlled vehicle in response to a control signal produced by the processor.

Abstract: A control system for steering front wheels or rear wheels of a controlled vehicle has a processing unit such as a microcomputer which determines a desired value of a dynamical variable such as yaw acceleration corresponding to sensed steering wheel angle and sensed vehicle speed by solving equations of motion of a vehicle in which parameters are set equal to desired values determined by a desired vehicle. From the desired value of the dynamical variable, the processing unit determines a desired value of a steering angle of the front or rear wheels, and commands a hydraulic actuator to steer the front or rear wheels so that the controlled vehicle behaves as if it were the desired vehicle. The controlled vehicle may have a mechanical steering linkage for steering the front wheels in a conventional manner, and the control system may be arranged to control the steering angle of the rear wheels.

Abstract: A system and method for controlling a steering reaction force in which at least one of motion state variables of a vehicle is estimated when a steering wheel of the vehicle is operated on the basis of a vehicle model which represents a mathematical model of the vehicle having a desired performance of motion, a target value of the steering reaction force imposed on a steering wheel is determined on the basis of the estimated value of the motion state variable, and the steering reaction force imposed on the steering wheel is generated so as to become substantially equal to the target value. The steering reaction force control system achieves the generation of the steering reaction force on the steering wheel on the basis of a vehicle turning motion information as motion state variables such as a lateral acceleration of the vehicle and/or yaw rate of the vehicle.

Abstract: Automotive brake control is performed by controlling brake pressure at front and rear wheels independently. The braking force at each of the front and rear wheels is controlled in accordance with monitored vehicle driving conditions so that the steering characteristics of the vehicle are held to predetermined characteristics even when vehicular brakes are applied during cornering. The braking pressure at front wheels is decreased when understeer characteristics increases due to braking. On the other hand, the braking pressure at the rear wheel is decreased when oversteer characteristics increases due to braking.

Abstract: An automotive suspension system has a roll stablizer with an adjustable torsion modulus. The torsion modulus of the stabilizer is adjusted depending upon road surface conditions and other parameters. A controller is associated with the stabilizer to adjust its torsion modulus. When the vehicle is moving on a relatively smooth road surface, the torsion modulus of the stabilizer is adjusted toward to a relatively high value. On the other hand, when the vehicle travels along a rough road, the torsion modulus is adjusted toward a lower value.

Abstract: A reference setting system for determining a target vehicle cornering behavior which can be used as a standard for determining a deviation of an actual cornering behavior such yaw rate and lateral acceleration of the vehicle, is arranged to have a steering angle sensor, a vehicle speed sensor and an operational unit which determines the target behavior from sensed steering angle and vehicle speed in accordance with predetermined equations of motion of a wheeled vehicle. The system may further has a differentiator for determining a steering speed from the steering angle, and a device for adjusting the target behavior in accordance with the steering speed.

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 control system for a controlled vehicle having front and rear wheels has a steering wheel angle sensor, a vehicle speed sensor, a controller such as a microcomputer, and an actuating system for varying actual steering gear ratio and actual rear wheel steer angle to approach desired values under command of the controller. From input quantities, the controller determines a desired steering gear ratio by using equations of motion so that a desired steady state side slip angle, and a desired steady state yaw rate gain can be obtained, and further determines a desired rear wheel steer angle by using the equations of motion so that desired response characteristics can be obtained in a steady state or in both steady and transient states.

Abstract: A control system for a controlled vehicle has a steering wheel angle sensor, a vehicle speed sensor, a turning behavior sensor such as a side speed sensor and a yaw rate sensor, an actuator such as a hydraulic system for altering a rear wheel steer angle in accordance with a desired angle value, and a controller such as a microcomputer for determining the desired angle value by solving three distinct vehicle models. The controller first solves a reference model representing a desired vehicle to determine a desired vehicle response to the steering wheel angle and vehicle speed, and then solves a first actual model representing the actual controlled vehicle to determine the desired rear wheel steer angle value required to cause the controlled vehicle to produce the desired response.

Abstract: A four wheel steer vehicle is equipped with a steering control system for controlling a rear wheel steer angle so that a rear end of the vehicle follows a path along which a front end moves. The control system includes a front wheel steer angle sensor, a controller for producing a control signal representing a desired rear wheel steer angle and an actuator for altering the rear wheel steer angle in response to the control signal produced by the controller. The controller estimates the path of the front end by calculating a value of a course angle of the front end from the front wheel steer angle each time the vehicle travels a predetermined short distance, and storing a predetermined number of the course angle values which are most recently determined. The controller determines the desired rear wheel steer angle so that the course angle of the rear end equals the oldest one of the stored course angle values of the front end.

Abstract: A control system for steering a controlled vehicle has a steering wheel angle sensor, a vehicle speed sensor, an actuator for altering a rear wheel steer angle, and a processor such as a microcomputer. The processor has a reference supplying section for determining a desired value of a vehicle motion variable such as a yaw rate by solving a desired mathematical vehicle model representing a postulated vehicle, and an actual motion estimating section for determining an estimated value of the vehicle motion variable by solving an actual vehicle model representing the controlled vehicle. The control system alters the rear wheel steer angle so as to reduce the difference between the desired and estimated values of the motion variable.

Abstract: A vehicle steering control system has a steering wheel angle sensor, a vehicle speed sensor, a control unit and an actuator for steering either (or both) of front and rear wheel pairs of a controlled vehicle. The control unit determines desired values of yaw rate and lateral acceleration corresponding to the sensed steering wheel angle and vehicle speed by using at least one desired mathematical vehicle model having desired vehicle response characteristics. Then, the control unit determines a desired value of a front or rear wheel steer angle (or both of the front and rear wheel angles) theoretically required to achieve the desired value of the yaw rate, and another desired value of the steer angle theoretically required to achieve the desired value of the lateral acceleration. Finally, the control unit determines a weighted average of two desired values of the steer angle by using weights which are functions of vehicle speed and/or steering wheel angular speed.

Abstract: A control system for steering either or both of front wheel pair and a rear wheel pair of a controlled vehicle has a processing unit such as a microcomputer for determining a desired vehicle behavior, and an actuator unit for steering either or both of the front and rear wheel pairs under command of the processing unit. The processing unit first determines a desired value of a dynamical variable such as a yaw acceleration corresponding to sensed steering input and sensed vehicle speed by solving equations of motion of a desired vehicle obtained by setting vehicle parameters appearing in the equations to desired values determined by the desired vehicle. The processing unit further determines a desired value of a steering angle of at least one of the front and rear wheel pairs which is required to achieve the desired value of the dynamical variable by solving equations of motion obtained by setting the vehicle parameters equal to actual values determined by the controlled vehicle.

Abstract: A system for estimating the state of a controlled vehicle's motion has a steering wheel angle sensor, a vehicle speed sensor, a sensor for sensing a first motion variable such as a yaw rate, a sensor for sensing a second motion variable such as a yaw acceleration, and a processing unit such as a microcomputer. In accordance with the sensor output signals, the processing unit produces a condition signal which is in a first signal state when the unit determines that the vehicle is in a steady-state turning motion, and in a second signal state when the unit determines that the vehicle is in a transient state turning motion.