Mixed steering assistance comprising a torque control loop setpoint-piloted by a position controller intended for path control

Patent metadata

Field	Value
Publication number	US-10399595-B2
Application number	US-201515317153-A
Country	US
Kind code	B2
Filing date	Jun 19, 2015
Priority date	Jun 24, 2014
Publication date	Sep 3, 2019
Grant date	Sep 3, 2019

Abstract

A method for managing a power steering system including at least one steering wheel and at least one assist motor, the method including a step of driver torque control, which involves evaluating a driver torque difference that corresponds to the difference between a predefined driver torque setpoint and the actual driver torque actually exerted by the driver on the steering wheel, then determining an engine torque setpoint for torque applied to the assist motor in order to reduce the driver torque difference, the driver torque setpoint being generated during a trajectory control step, which involves evaluating a trajectory difference, for example a position difference, which corresponds to the difference between a trajectory setpoint, of the position setpoint type, which depends on a reference trajectory, and the actual trajectory of the vehicle, given by the measured position of the power steering, then determining, from the trajectory difference, a driver torque setpoint intended to reduce the trajectory difference.

First claim

The invention claimed is:

1. A method for managing a power steering for a vehicle, the power steering including at least one steering wheel and at least one assist motor, the method comprising:
a driver torque control step, which is a driver torque control closed loop, the driver torque control step comprising:
measuring an effective driver torque that is actually exerted by a driver on the steering wheel,
comparing the effective driver torque with a predetermined driver torque setpoint in order to assess a driver torque deviation that corresponds to a difference between the effective driver torque and the driver torque setpoint, and
determining from the driver torque deviation a motor torque setpoint intended to be applied to the assist motor in order to reduce the driver torque deviation,

wherein the predetermined driver torque setpoint is generated during a path control step, which is a path control closed loop, the path control step comprising:
measuring an effective value of at least one path parameter, which is representative of an effective path of the vehicle, and
comparing the path parameter with a path setpoint, which is predetermined depending on a reference path that the vehicle automatically follows, in order to assess a path deviation that corresponds to a difference between the path setpoint and the effective value of the path parameter, and then determining, from the path deviation, the driver torque setpoint,

wherein the path control closed loop and the driver torque control closed loop are nested in series.

2. The method according to claim 1 , wherein, during the path control step, an effective position of the power steering is measured, and then the effective position is compared with a position setpoint, which is predetermined depending on the reference path that the vehicle automatically follows, in order to assess a position deviation that corresponds to a difference between the position setpoint and the effective position of the power steering, and from the position deviation, the driver torque setpoint is determined.

3. The method according to claim 1 , wherein the path control step further includes comparing the driver torque setpoint with a predetermined driver torque saturation threshold and limiting the driver torque setpoint to the value of the predetermined driver torque saturation threshold if the driver torque setpoint exceeds the predetermined driver torque saturation threshold.

4. The method according to claim 3 , wherein the predetermined driver torque saturation threshold is between 1 N·m and 4 N·m.

5. The method according to claim 1 , wherein the path control step further includes using a driver torque setpoint determination law, in order to determine the driver torque setpoint from the path deviation, wherein the driver torque setpoint determination law is in the form of a function centered on the path setpoint, and associates to every effective value of the path parameter, a corresponding driver torque setpoint.

6. The method according to claim 5 , wherein the function that is representative of the driver torque setpoint determination law is an S-shaped curve presenting an increasing central domain that is centered on the path setpoint, wherein the increasing central domain is surrounded by two asymptotic domains with a slope that is lesser than the slope of the central domain, or with a slope that is substantially zero.

7. The method according to claim 1 , wherein the path control step further includes using an automatic piloting function for parking maneuver or an automatic piloting function for following a traffic lane, in order to determine the path setpoint.

8. A non-transitory data medium readable by a computer and containing computer program code elements ensuring the execution of a method according to claim 1 when the medium is read by a computer.

9. A power steering management system comprising:
non-transitory computer executable instructions; and
a processor configured to execute the non-transitory computer executable instructions to cause the processor to:
perform a driver torque control step, which is a driver torque control closed loop, the driver torque control step comprising:
receiving as an input a driver torque setpoint and a measurement of an effective driver torque that is actually exerted by the driver on the steering wheel,
determining a driver torque deviation that corresponds to a difference between the effective driver torque and the driver torque setpoint, and
providing as an output a motor torque setpoint based upon the driver torque deviation, the motor torque setpoint being intended to be applied to the assist motor in order to reduce the driver torque deviation,

wherein the predetermined driver torque setpoint is generated during a path control step, which is a path control closed loop, the path control step comprising:
measuring an effective value of at least one path parameter, which is representative of an effective path of the vehicle, and
comparing the path parameter with a path setpoint, which is predetermined depending on a reference path that the vehicle automatically follows, in order to assess a path deviation that corresponds to a difference between the path setpoint and the effective value of the path parameter, and then determining, from the path deviation, the driver torque setpoint,

wherein the path control closed loop and the driver torque control closed loop are nested in series.

10. The power steering management module according to claim 9 , wherein during the path control step, an effective position of the power steering is measured, and then the effective position is compared with a position setpoint, which is predetermined depending on the reference path that the vehicle automatically follows, in order to assess a position deviation that corresponds to a difference between the position setpoint and the effective position of the power steering, and from the position deviation, the driver torque setpoint is determined.

Assignees

• Jtekt Europe Sas

Inventors

• Moretti Romain
• Leydier Luc

Classifications

• B62D5/0472

  for damping vibrations · CPC title

• B62D5/0463

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

• B62D1/286

  Systems for interrupting non-mechanical steering due to driver intervention · CPC title

• B62D1/28 Primary

  non-mechanical {, e.g. following a line or other known markers} · CPC title

• B62D15/0285

  Parking performed automatically · CPC title