Method for determining the gradient of a roadway
First Claim
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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Accused Products
Abstract
The gradient of a roadway in the direction of travel of the vehicle is identified from signals present in the vehicle without any additional sensor systems. A freely rolling state of the at least one driven axle of the vehicle is detected at least once. In this state, the wheels of the driven axle also roll free of slip. In order to balance out the wheel speeds between the driven axles and the non-driven axles, the difference speed between the wheel speed of a driven axle and the wheel speed of a non-driven axle is identified. At the same time, the value of the braking, that is to say the value of the deceleration of the vehicle, is measured. The value of a gradient constant is identified from the identified values of the difference speeds and the braking operations. The gradient of the roadway can be determined with the gradient constant from the values of the difference speed and the values of the braking then identified. The gradient information can then be used to control the vehicle.
16 Citations
22 Claims
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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:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A system for determining a gradient of a roadway upon which a vehicle is travelling in a travelling direction, the system comprising:
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wheel speed sensors for detecting and outputting wheel speed signals for at least one non-driven axle and at least one driven axle of the vehicle; a processor including a memory programmed so as to perform the following steps; detecting a freely rolling state of the at least one driven axle; identifying for the freely rolling state at least 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 z-- HSP; detecting 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 for the drive state a second value of braking 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 a gradient constant from said identified values ds-- HSP, ds-- SPh, z-- HSP, z-- SPh; determining a gradient 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 and present values of the braking z-- SPh and the speed difference ds-- SPh between the wheel speed at said driven axle and said non-driven axle; and wherein the gradient of the roadway determined in the processor is used to control the vehicle.
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Specification