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Rear wheel steering angle control system for four wheel steer vehicle

  • US 4,778,023 A
  • Filed: 02/24/1987
  • Issued: 10/18/1988
  • Est. Priority Date: 09/20/1984
  • Status: Expired due to Fees
First Claim
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1. A rear wheel steering control system for a vehicle having steerable front wheels and steerable rear wheels, comprising:

  • front wheel angle sensing means for sensing an actual front wheel steering angle of said front wheels and producing a first signal representing said actual front wheel steering angle,distance measuring means for measuring a vehicle speed and a travel distance traveled by said vehicle and producing a second signal representing said travel distance,a gear position sensor for sensing a gear position of a transmission of said vehicle and producing a third signal only when said transmission is in a forward driving position for driving said vehicle forwardly,rear wheel actuating means for steering said rear wheels in a direction represented by a control signal, in such an amount that an actual rear wheel steering angle of said rear wheels is made equal to a steering angle represented by said control signal, andrear wheel control means for steering said rear wheels by sending said control signal to said rear wheel actuating means, said control means comprising control signal producing means responsive to said first signal for determining a desired rear wheel steering angle in accordance with said actual front wheel steering angle currently sensed by said front wheel angle sensing means and for steering said rear wheels by producing said control signal representing said desired rear wheel steering angle in a normal mode such that the steering angle represented by said control signal is immediately made equal to said desired rear wheel steering angle, condition discriminating means responsive to said third signal for producing a condition signal which is in an on state if said third signal is present, and in an off state if said third signal is absent, and control signal modifying means responsive to said second signal and said condition signal for steering said rear wheels in a direction opposite to the steering direction of said front wheels by modifying said control signal in a delayed mode such that the steering angle represented by said control signal increases gradually to said desired rear wheel steering angle in dependence on said travel distance if said condition signal is in said on state.

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