Method for estimating a value of a friction force exerted on a part of a power steering system by means of a mathematical model

Patent metadata

Field	Value
Publication number	US-12060119-B2
Application number	US-202017604955-A
Country	US
Kind code	B2
Filing date	Apr 22, 2020
Priority date	Apr 26, 2019
Publication date	Aug 13, 2024
Grant date	Aug 13, 2024

Abstract

A method for estimating a value of a friction force exerted on a part of a power steering system of a vehicle, the part of the power steering system including at least one motor exerting a motor torque, the value of the friction force making it possible to modify the motor torque, by means of a mathematical model.

First claim

The invention claimed is:

1. A method of estimating a value of a frictional force exerted on a portion of a power steering system of a vehicle, said portion of the power steering system comprising at least one motor exerting a motor torque, said value of the frictional force making it possible to modify the motor torque, wherein it comprises the following steps:
determining a portion of a model power steering system corresponding to a mathematical model virtually representing the portion of the power steering system, wherein the mathematical model comprises a frictional force model,
measuring, on the portion of the power steering system, a value of at least one input variable,
calculating at least one output parameter by means of the mathematical model and the at least one input variable,
measuring, on the portion of the power steering system, a value of at least one output variable representing a physical quantity similar to the at least one output parameter,
calculating at least one deviation between the at least one output parameter and the at least one output variable,
correcting a value of at least one internal parameter of said mathematical model as a function of the deviation and of an internal coefficient,
determining the value of the frictional force from the at least one corrected internal parameter.

2. The estimation method according to claim 1 , wherein the mathematical model is a 1st-order mathematical model, comprising a model mass, equivalent to a set of inertias of the portion of the model power steering system, which is subjected to at least one force exerted on the portion of the model power steering system.

3. The estimation method according to claim 1 , wherein the frictional force of the mathematical model is determined by a LuGre model.

4. The estimation method according to claim 1 , wherein the internal coefficient enabling the correction of the at least one internal parameter is determined by an application of Lyapunov's theorem.

5. The estimation method according to claim 1 , wherein the at least one input variable is selected from: the motor torque, a steering wheel torque, a lateral acceleration of the vehicle or a force on the tie rods.

6. The estimation method according to claim 1 , wherein the output parameter and the output variable correspond to a rotational speed of the motor.

Assignees

• Jtekt Europe Sas

Inventors

• Gaudin Serge
• Baudouin Nicolas
• Moulaire Pascal

Classifications

• B62D5/0463

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

• G01L3/26

  Devices for measuring efficiency, i.e. the ratio of power output to power input · CPC title

• G01L5/221

  to steering wheels, e.g. for power assisted steering · CPC title

• B62D5/0481 Primary

  monitoring the steering system, e.g. failures · CPC title

• B62D5/0421 Primary

  Electric motor acting on or near steering gear · CPC title