Rear-wheel steering system for four-wheel steering vehicle
First Claim
1. In a rear-wheel steering system for four-wheel steering vehicle having a front-wheel steering angle sensor for detecting a front-wheel steering angle, a vehicle speed sensor for detecting a vehicle speed, a control unit for carrying out rear-wheel steering control in accordance with an actual front-wheel steering angle represented by a deviation of the front-wheel steering angle from a neutral point of the steering and the vehicle speed, and an actuator controlled by the control unit to steer the rear wheels, the improvement of the rear-wheel steering system comprising:
- detecting means for detecting front-wheel steering force, front-wheel lateral force or acceleration in the lateral direction of the vehicle and for producing a detection signal; and
front-wheel neutral point correcting means provided in said control unit for resetting said neutral point of the steering to a reference value of said front-wheel steering angle at a time when said detection signal indicates a straight-ahead driving state of the vehicle.
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Accused Products
Abstract
A rear-wheel steering system is provided in a four-wheel steering vehicle having at least a front-wheel steering angle sensor, a vehicle speed sensor, a control unit for carrying out rear-wheel steering control in dependency on signals detected by these sensors, and an electric motor controlled by the control unit to steer the rear wheels. This rear-wheel steering system is provided with detecting means for detecting front-wheel steering force, front-wheel lateral force or lateral acceleration of the vehicle. The control unit is provided with a front-wheel neutral point correction means for determining the zero point of the front-wheel steering angle which causes the rear-wheel steering angle to be zero with respect to a signal indicating that the front-wheel steering force, the front-wheel lateral force or the lateral acceleration of the vehicle thus detected by the detecting means is substantially zero.
25 Citations
6 Claims
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1. In a rear-wheel steering system for four-wheel steering vehicle having a front-wheel steering angle sensor for detecting a front-wheel steering angle, a vehicle speed sensor for detecting a vehicle speed, a control unit for carrying out rear-wheel steering control in accordance with an actual front-wheel steering angle represented by a deviation of the front-wheel steering angle from a neutral point of the steering and the vehicle speed, and an actuator controlled by the control unit to steer the rear wheels, the improvement of the rear-wheel steering system comprising:
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detecting means for detecting front-wheel steering force, front-wheel lateral force or acceleration in the lateral direction of the vehicle and for producing a detection signal; and front-wheel neutral point correcting means provided in said control unit for resetting said neutral point of the steering to a reference value of said front-wheel steering angle at a time when said detection signal indicates a straight-ahead driving state of the vehicle. - View Dependent Claims (2, 3, 4, 5)
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6. A rear-wheel steering system for a four-wheel steering vehicle, having a front-wheel steering angle sensor for detecting a front-wheel steering angle, a vehicle speed sensor for detecting vehicle speed, a control unit for controlling the steering of the rear-wheel in accordance with said front-wheel steering angle and said vehicle speed and for generating a control signal, an actuator responsive to said control signal for controlling the steering of the rear-wheel, a rear-wheel steering speed sensor for detecting an actual rear-wheel steering speed, and a rear-wheel steering angle sensor for detecting an actual rear-wheel steering angle, the improvement of the system which comprises:
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detecting means for detecting front-wheel steering force, front-wheel lateral force or lateral acceleration of the vehicle and for producing a detection signal; front-wheel neutral point correcting means for correcting a neutral point of the steering of the front wheels by a value of said front-wheel steering angle at a time when said detection signal indicates a straight-ahead driving state of the vehicle; calculating means for calculating an actual front-wheel steering angle corresponding to the difference between said neutral point and said front-wheel steering angle detected by the front-wheel steering angle sensor; setting means responsive to said actual front-wheel steering angle and said vehicle speed for setting a reference rear-wheel steering angle; determining means responsive to said reference rear-wheel steering angle for determining a reference rear-wheel steering speed; computing means for computing a speed deviation between said reference rear-wheel steering speed and said actual rear-wheel steering speed and for producing a speed deviation signal; and a driving circuit responsive to said speed deviation signal for driving the actuator in said reference rear-wheel steering speed so as to keep said four-wheel steering vehicle in a straight running direction.
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Specification