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Rear wheel steering angle controlling apparatus of four-wheel steering vehicle

  • US 5,524,079 A
  • Filed: 08/27/1993
  • Issued: 06/04/1996
  • Est. Priority Date: 09/01/1992
  • Status: Expired due to Fees
First Claim
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1. In an apparatus for controlling a rear wheel steering angle of a four-wheel steering vehicle which includes a vehicle speed sensor for detecting the speed of a vehicle, a yaw rate sensor for detecting a yaw rate, a steering wheel angle sensor for detecting a rotary angle of a steering wheel, a rear wheel steering angle sensor for detecting a rear wheel steering angle, and an electric motor controlling means for steering a rear wheel in accordance with a rear wheel steering angle instruction signal, the improvement comprising:

  • a target yaw rate calculating means for calculating a target yaw rate for a moving vehicle in accordance with a vehicle speed and a steering wheel angle;

    a vehicle speed characteristic estimating means for estimating a vehicle dynamic characteristic variation term due to a vehicle speed change in accordance with known values of a yaw rate, steering wheel angle and rear E wheel steering angle a microtime before the estimation, without directly detecting a vehicle speed change;

    a control amount calculating means having an input thereof connected to outputs of said estimating means and said target yaw rate calculating means and yaw rate sensor, for calculating a rear wheel steering angle instruction signal value fed to said electric motor controlling means based on the resultant value obtained by said vehicle speed characteristic estimating means in accordance with error dynamics defined by a deviation between the actual yaw rate detected by said yaw rate sensor and the target yaw rate calculated by said target yaw rate calculating means so that the deviation is minimized.

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