Method for controlling a steer-by-wire steering system
First Claim
1. A method for controlling a steer-by-wire steering system of a vehicle having at least one steering axle having at least two steer wheels each controlled by a control member, wherein the method comprises:
- detecting a difference in behaviour between a first steer wheel and a second steer wheel thereby indicating, asymmetric steer wheel adhesion, the first steer wheel being in contact with a first area which exhibits a first coefficient of adhesion and the second steer wheel being in contact with a second area which exhibits a second coefficient of adhesion, the first coefficient of adhesion being higher than the second coefficient of adhesion,calculating a theoretical yaw parameter as a function at least of an actual speed of the vehicle and of an actual position of the control member,measuring an actual yaw parameter using a yaw sensor,comparing the actual yaw parameter with the theoretical yaw parameter,angling the first steer wheel in contact with the area exhibiting the first coefficient of adhesion by a first angle whereby the first steer wheel is oriented in a direction opposing the yaw and angling the second steer wheel in contact with the area exhibiting, the second coefficient of adhesion by a second angle wherein the second angle is between a value such that the second steer wheel is oriented substantially in a vehicle direction of travel, and a value whereby the second steer wheel is oriented towards the first steer wheel, if a difference between the actual yaw parameter and the theoretical yaw parameter exceeds a reference data.
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Accused Products
Abstract
A method is aimed at controlling a steer-by-wire steering system of a vehicle having at least one steering axle having at least two steer wheels electronically controlled by a control member. In the case of asymmetric adhesion conditions, the method anticipates steering into the skid for the first steer wheel that is on the surface exhibiting the higher coefficient of adhesion—for example asphalt—so as to counter a moment applied to the Z-axis. At the same time, the second steer wheel which is on the surface having the lower coefficient of adhesion—for example a sheet of black ice—remains in the vehicle direction of travel or is oriented towards the second steer wheel in a snow plough mode. The vehicle stability is vastly improved when the vehicle regains an area of uniform adhesion.
9 Citations
17 Claims
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1. A method for controlling a steer-by-wire steering system of a vehicle having at least one steering axle having at least two steer wheels each controlled by a control member, wherein the method comprises:
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detecting a difference in behaviour between a first steer wheel and a second steer wheel thereby indicating, asymmetric steer wheel adhesion, the first steer wheel being in contact with a first area which exhibits a first coefficient of adhesion and the second steer wheel being in contact with a second area which exhibits a second coefficient of adhesion, the first coefficient of adhesion being higher than the second coefficient of adhesion, calculating a theoretical yaw parameter as a function at least of an actual speed of the vehicle and of an actual position of the control member, measuring an actual yaw parameter using a yaw sensor, comparing the actual yaw parameter with the theoretical yaw parameter, angling the first steer wheel in contact with the area exhibiting the first coefficient of adhesion by a first angle whereby the first steer wheel is oriented in a direction opposing the yaw and angling the second steer wheel in contact with the area exhibiting, the second coefficient of adhesion by a second angle wherein the second angle is between a value such that the second steer wheel is oriented substantially in a vehicle direction of travel, and a value whereby the second steer wheel is oriented towards the first steer wheel, if a difference between the actual yaw parameter and the theoretical yaw parameter exceeds a reference data. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 16, 17)
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- 14. The method according to claim , wherein the second angle formed by the second steer wheel exhibiting a second coefficient of adhesion and the longitudinal axis of the vehicle is nil.
Specification