Abstract: A vehicle having learning control includes a running condition detecting device for detecting a driving condition of the vehicle, a running characteristic control device for controlling a control gain to change a running characteristic of the vehicle and a gain control device for learning the running characteristic of the vehicle to change the control gain. The running characteristics of the vehicle can be controlled corresponding to various running conditions.

Abstract: In a four wheel steering system, the rear wheel turning mechanism is connected to the front wheel turning mechanism by way of a rear wheel turning angle ratio changing mechanism which is mechanically connected to both the front wheel turning mechanism and the rear wheel turning mechanism and transmits the mechanical displacement input thereinto from the front wheel turning mechanism to the rear wheel turning mechanism to drive the same by an amount the ratio of which to the amount of mechanical displacement input into the rear wheel turning angle ratio changing mechanism gives a predetermined rear wheel turning angle ratio. The rear wheel turning angle ratio changing mechanism is controlled in such a way that, when the front wheels are turned from the neutral position in a middle vehicle speed range, makes the rear wheel turning angle ratio negative for a moment immediately after initiation of turning of the front wheels and thereafter turns the same positive.

Abstract: A system for steering a rear wheel of a vehicle having a mechanism for altering a steering ratio, .THETA.S, based on an amount of steering of the rear wheel to an amount of steering a front wheel. The system is disposed in an interconnecting mechanism for mechanically interconnecting the mechanism for steering the front wheel with the mechanism for steering the rear wheel. The value of .THETA.S is set by the following formula:.THETA.S=C1+B.multidot.C3.multidot..vertline.Y.vertline.-C4.multidot..vertl ine.dY.vertline.where .THETA.S is a steering ratio;Y is a yaw rate of a vehicle body;dY is a yaw acceleration of the yaw rate;C1 is a basic steering characteristic term;C3 is a yaw rate control gain;C4 is a yaw acceleration control gain; andB is a correction coefficient control gain term.The value of B increases when the amount of steering of the front wheel is small and decreases when the amount of steering of the front wheel is large.

Abstract: Two support members which are supported swingably to the vehicle body through the medium of the support axis extending in up and down direction are provided at the vehicle body end portions of two left and right suspension arm members connecting left and right rear wheels to the vehicle body. Lever parts are extended from the support members toward the opposing direction to each other and are interconnected by a link member. One of the two support members is driven by one actuator for rotation around an support axis, whereby left and right two suspension arm members move in vehicle widthwise direction, opposite to each other, and in synchronism with each other and thus left and right rear wheels are steered symmetrically in toe-in direction or toe-out direction.

Abstract: A device for steering the rear wheels of a vehicle has a first motor controlled at least with respect to the steering angle of the steering wheel, a gear change mechanism for changing gear ratios, a second motor for controlling the gear ratio by driving the gear change mechanism, a steering mechanism for steering the rear wheels by transmitting a portion of the force equal to the product of the amount that the first motor is driven and the amount that the second motor is driven, a motor failure determination device for detecting motor failure when the amount that either of the first or second motors is driven is zero and the other of the motors is operated, and a control device for controlling both motors so that when motor failure is detected in one of the motors, the amount that the other motor is driven is brought to zero.

Abstract: A vehicle rear wheels steering apparatus is provided with a guide member having a guideway capable of freely tilting toward the axis of the rod member. Therefore, when the rod member rotates around the axis, an operating member provided on the outside of the rod member rotates around the rod member axis along the guideway to steer the rear wheels by an amount corresponding to an amount of rotation of the rod member and an amount of tilting of the guideway.

Abstract: A rear wheel steering apparatus for a vehicle, comprises a hydraulic cylinder for displacing a steering rod connected to left and right rear wheels axially, a centering spring for biasing the steering rod toward a neutral position, and a centering spring cancelling mechanism for preventing a biasing force of the centering spring from acting on the steering rod. A partition wall of the hydraulic cylinder defines an oil chamber in the cylinder and is formed as a cup shape having a central concave portion which constitutes a pressure chamber of the centering spring cancelling mechanism.

Abstract: A rear wheel turning system for a four-wheel steered vehicle includes a rear wheel turning mechanism for turning the rear wheels of the vehicle, a front wheel turning angle sensor which detects a turning angle of front wheels .theta..sub.F, a vehicle speed sensor which detects a vehicle speed V, a yaw rate detector which detects a yaw rate .PSI. of the vehicle, a yaw acceleration detector which detects a yaw acceleration .PSI. of the vehicle, and a control unit which causes the rear wheel turning mechanism to turn the rear wheels by a target rear wheel turning angle TG.theta..sub.R which is defined by formulaTG.theta..sub.R =-K.sub.1 .theta..sub.F +K.sub.2 .multidot.V.multidot..PSI.+K.sub.3 .multidot.V.multidot..PSI.wherein K.sub.1, K.sub.2 and K.sub.3 respectively represent positive coefficients. The coefficient K.sub.3 is increased with increase in the vehicle speed V over a predetermined range of vehicle speed where the coefficient K.sub.2 is constant.

Abstract: A rear steering control system for a motor vehicle includes an antiskid braking system which controls a braking force in a brake device in a respective wheel in accordance with a deceleration condition of the respective wheel so as to prevent wheel locking in a braking operation. The sytem includes a rear steering control system for establishing a ratio of steering amount of the rear wheels to that of the front wheels as a predetermined steering ratio characteristic. An input device inputs an operation condition of the antiskid braking system and an control condition of the brake device for the respective wheel conducted by the antiskid braking system to the rear steering control system. A device is provided in the system for amending the predetermined steering ratio characteristic in accordance with the control condition of the brake device for the respective wheel when the antiskid braking system is in operation.

Abstract: A front drive vehicle is provided with a four-wheel steering system and a traction control system. A control system for the vehicle detects whether a failure occurs in the traction control system, and causes the rear wheel turning mechanism to turn the rear wheels according to corrected rear wheel turning characteristics when it is determined that a failure occurs in the traction control system. The corrected rear wheel turning characteristics are shifted toward the reverse phase side with respect to the original rear wheel turning characteristics.

Abstract: A four-wheel-steered vehicle provided with a slip control mechanism which has a slip ratio sensor for detecting the slip ratio of the wheels and controls slip of wheels of the vehicle when the slip ratio of the wheels reaches a first preset value. The four-wheel steering mechanism turns the rear wheels according to first rear wheel turning characteristics in response to turning of the front wheels when the slip ratio of the wheels is smaller than a second preset value which is smaller than the first preset value and turns the rear wheels according to second rear wheel turning characteristics when the slip ratio reaches the second preset value.