Adaptation of a drift gain according to steering wheel torque in order to improve the feel of a power-steering system

Patent metadata

Field	Value
Publication number	US-2021188344-A1
Application number	US-201816650416-A
Country	US
Kind code	A1
Filing date	Sep 24, 2018
Priority date	Sep 25, 2017
Publication date	Jun 24, 2021
Grant date	—

Abstract

A power-steering device includes a steering wheel and an assistance motor controlled by a controller which uses at least one closed-loop control law ensuring an adjustment of the steering wheel torque, the controller including at least one feedback arm which calculates a drift component by measuring or assessing an actual force parameter corresponding to the actual steering wheel torque, by next calculating a time drift value of the actual force parameter, and then multiplying the time drift value by a drift gain, wherein the controller uses three-dimensional cartography to adjust the drift gain according to a portion of the actual force parameter and the longitudinal velocity of the vehicle, according to a first domain, referred to as “parking domain”, which extends from a longitudinal vehicle velocity of zero to a predetermined longitudinal velocity threshold, and a second domain, referred to as “driving domain”, which extends beyond the longitudinal velocity threshold.

First claim

1 . A power steering device comprising a steering wheel on which a driver can exert a maneuvering force, called «steering wheel torque», as well as an assist motor controlled by a controller which uses at least one closed-loop control law ensuring a regulation of said steering wheel torque, said controller comprising at least one feedback branch, called «derivative branch», which calculates a component called «derivative component» by measuring or by evaluating an actual force parameter which corresponds to the actual steering wheel torque, or to a magnitude which is an image of the actual steering wheel torque whose value and variations are correlated to the value and variations of said actual steering wheel torque, then by calculating a time derivative value of said actual force parameter, then by multiplying said time derivative value by a derivative gain, said device, wherein the controller uses a three-dimensional mapping to adjust the derivative gain as a function, on the one hand, of the actual force parameter, and on the other hand, of the vehicle longitudinal speed.

2 . The device according to claim 1 , wherein the three-dimensional mapping comprises a first domain, called «parking domain», which extends from a zero vehicle longitudinal speed to a non-zero predetermined longitudinal speed threshold, and a second domain, called «running domain», which extends beyond said longitudinal speed threshold, and in that, in the running domain, the derivative gain decreases when the actual force parameter increases, while, in the parking domain, the derivative gain increases when the actual force parameter increases.

3 . The device according to claim 2 , wherein the longitudinal speed threshold which marks the border between the parking domain and the running domain is equal to or less than 5 km/hr.

4 . The device according to claim 2 , wherein the three-dimensional mapping comprises at least one inversion point, located at the border between the parking domain and the running domain, and from which, if the mapping is described in the direction of an increasing longitudinal speed and in the direction of a decreasing actual force parameter, then the derivative gain increases, while if the mapping is described always in the direction of an increasing longitudinal speed, but in the direction of an increasing actual force parameter, the derivative gain decreases.

5 . The device according to claim 2 , wherein the running domain comprises:
a first sub-domain called «neighborhood sub-domain of the straight line», which extends from a zero value of the actual force parameter to a first predetermined force threshold, and in which the derivative gain remains greater than a first gain threshold, called «ceiling threshold», a second sub-domain called «turning sub-domain», which extends from and beyond a second predetermined force threshold, greater than the first force threshold, and in which the derivative gain remains less than a second gain threshold, called «floor threshold», strictly below the ceiling threshold, a third intermediate sub-domain, called «transition sub-domain», which extends from the first force threshold to the second force threshold and in which, when the actual force parameter increases, at a given longitudinal speed, the derivative gain decreases from the ceiling threshold to the floor threshold.

6 . The device according to claim 5 , wherein the floor threshold increases when the longitudinal speed falls, in the direction of the longitudinal speed threshold, below a certain pre-border threshold, which is greater than said longitudinal speed threshold, and which is for example comprised between 60 km/h and 30 km/h.

7 . The device according to claim 1 , wherein the three-dimensional mapping is designed so that the resulting derivative gain induces a phase delay, between a driver maneuver triggering a variation of the steering wheel torque and an actual change in the of the vehicle yaw rate which results from said maneuver, which is comprised between at least 50 ms.

Assignees

• Jtekt Europe Sas

Inventors

• Moulaire Pascal
• Michelis André
• Gaudin Serge

Classifications

• B62D6/00

  Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits (means for initiating a change in direction B62D1/00; steering valves B62D5/06; combined with means for inclining the vehicle body or wheels on bends B62D9/00) · CPC title

• B62D5/006

  power actuated · CPC title

• B62D5/0463 Primary

  calculating assisting torque from the motor based on driver input · CPC title