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Method for determining the gradient of a roadway

  • US 5,797,109 A
  • Filed: 12/07/1995
  • Issued: 08/18/1998
  • Est. Priority Date: 12/07/1994
  • Status: Expired due to Term
First Claim
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1. A method for determining a gradient of a roadway upon which a vehicle is travelling in a travelling direction from measured signals fed to an evaluation unit, the method comprising the steps of:

  • detecting and feeding wheel speeds of at least one nondriven axle and at least one driven axle of the vehicle to the evaluation unit;

    detecting a freely rolling state of the at least one driven axle in the evaluation unit;

    identifying in the evaluation unit, when the freely rolling state is detected, a value of a speed difference ds-- HSP between the wheel speed of said one driven axle and the wheel speed of said one non-driven axle, and a value of a braking operation;

    detecting in the evaluation unit a drive state of a driven axle which is steady and is at a prescribed time interval from said freely rolling state of said at least one driven axle;

    identifying in the evaluation unit, when the drive state is detected, a second value of the braking operation z-- SPh and a second value of the speed difference ds-- SPh between the wheel speed at said driven axle and said non-driven axle;

    determining in the evaluation unit a gradient constant mk from said identified values ds-- HSP, ds-- SPh, z-- HSP, z-- SPh;

    determining in the evaluation unit a gradient p of the roadway in the travelling direction when there are successive states of said driven axle which have been detected as steady, said gradient of the roadway in the travelling direction being determined from said gradient constant mk and present values of the braking operation z-- SPh and the speed difference ds-- SPh between the wheel speed at said driven axle and said non-driven axle; and

    using said gradient of the roadway determined in the evaluation unit to control the vehicle.

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