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Method and system for providing secondary vehicle directional control through braking

  • US 6,808,041 B2
  • Filed: 07/25/2002
  • Issued: 10/26/2004
  • Est. Priority Date: 02/11/2000
  • Status: Expired due to Term
First Claim
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1. A method for implementing directional control of a motor vehicle, the method comprising:

  • determining whether a failure of a primary steering system of the motor vehicle exists;

    if a failure of the primary steering system exists, then creating a yaw moment on the vehicle by causing a differential longitudinal force to be applied with respect to a first wheel on one side of the vehicle and a second wheel on an opposite side of the vehicle, thereby causing the vehicle to turn in a commanded direction;

    wherein said causing a differential longitudinal force further comprises applying a braking force to at least one of said first and second wheels of the vehicle;

    wherein said creating a yaw moment on the vehicle further comprises;

    determining a desired directional response, determining whether a desired braking operation exists, and generating a brake torque output signal, based upon said desired directional response and whether said desired braking operation exists, said brake torque output signal being used in said selectively applying a braking force;

    wherein said desired directional response is determined by a closed-loop yaw rate control mechanism, said closed-loop yaw rate control mechanism being implemented by;

    generating an error signal, said error signal representing the difference between a desired yaw rate and said vehicle yaw rate; and

    said desired yaw rate being determined from a steering wheel angle and a vehicle speed;

    wherein said desired yaw rate is further determined by;

    inputting said steering wheel angle and said vehicle speed into a lookup table, said lookup table thereby determining a desired steady state yaw rate; and

    filtering said desired steady state yaw rate through a second order filter.

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