Four-wheel steering control system for vehicle
First Claim
1. A steering system for a vehicle having at least steerable front wheels comprising:
- steering input means comprising a steering wheel and a steering sensor for determining a steering input which is an angular displacement of the steering wheel,front steering means connected with the steering input means for determining a first output angle from the steering input in accordance with a first transfer characteristic between the steering input and the first output angle and controlling a steering angle of the front wheels so that the steering angle of the front wheels is maintained equal to the first output angle, the first transfer characteristic being a function of steering frequency such that both the gain and phase difference of the first transfer characteristic vary as the steering frequency varies, andrear steering means connected with the steering input means for determining a second output angle from the steering input in accordance with a second transfer characteristic between the steering input and the second output angle which is different from the first transfer characteristic, and controlling a steering angle of the rear wheels so that the steering angle of the rear wheels is maintained equal to the second output angle.
1 Assignment
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Accused Products
Abstract
A vehicle steering control system for steering both front and rear wheels is so arranged that a transfer function between a driver'"'"'s steering input and a front wheel steering angle, and a transfer function between the steering input and a rear wheel steering angle are differentiated from each other so as to obtain an optimum cornering characteristic of the vehicle. The system has a steering input sensor, a vehicle speed sensor, means for determining the transfer function for the front wheels from a steering frequency and a vehicle speed, means for determining the transfer function of the rear wheels, a front wheel actuator for steering the front wheels, and a rear wheel actuator for steering the rear wheels. The means for determining the transfer function of the rear wheels may be an electronic circuit, or a hydraulic fluid flow restrictor such as an orifice, or a mechanical gearing.
28 Citations
25 Claims
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1. A steering system for a vehicle having at least steerable front wheels comprising:
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steering input means comprising a steering wheel and a steering sensor for determining a steering input which is an angular displacement of the steering wheel, front steering means connected with the steering input means for determining a first output angle from the steering input in accordance with a first transfer characteristic between the steering input and the first output angle and controlling a steering angle of the front wheels so that the steering angle of the front wheels is maintained equal to the first output angle, the first transfer characteristic being a function of steering frequency such that both the gain and phase difference of the first transfer characteristic vary as the steering frequency varies, and rear steering means connected with the steering input means for determining a second output angle from the steering input in accordance with a second transfer characteristic between the steering input and the second output angle which is different from the first transfer characteristic, and controlling a steering angle of the rear wheels so that the steering angle of the rear wheels is maintained equal to the second output angle. - View Dependent Claims (2, 3, 4, 5, 6, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 23, 24, 25)
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- 7. wherein the rear steering means turns the rear wheels in the same direction as the front wheels at least in the high vehicle speed range.
Specification