# US 12,594,987 B2 · Electronic power steering system rack force observer vehicle diagnostics

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- Number: US 12,594,987 B2
- Document ID: US12594987B2
- Status: Granted
- Kind: B2
- Application number: 17/188,388
- Filed: 2021-03-01
- Published: 2022-09-01
- Granted: 2026-04-07
- Earliest claimed: 2021-03-01
- Assignees: Steering Solutions IP Holding Corporation
- Applicants: Continental Automotive Systems, Inc.; Steering Solutions IP Holding Corporation
- Inventors: Clinton L. Schumann; Scott T. Sanford; Geoff Bauer; Joseph A. LaBarbera
- Web page: https://patentgrep.com/patent/US12594987B2

## CPC

- B62D 5/0481: {monitoring the steering system, e.g. failures}
- B62D 5/046: {Controlling the motor}
- B62D 15/021: {Determination of steering angle}
- B62D 15/025: {Active steering aids, e.g. helping the driver by actively influencing the steering system after environment evaluation (B62D1/28 takes precedence)}
- G01S 19/42: Determining position
- G07C 5/0808: {Diagnosing performance data (testing of vehicles G01M17/00; testing of electrical installation on vehicles G01R31/005)}
- G07C 5/0816: {Indicating performance data, e.g. occurrence of a malfunction}
- B62D 6/002: {computing target steering angles for front or rear wheels (B62D7/159 takes precedence)}
- B62D: MOTOR VEHICLES; TRAILERS (steering, or guiding on a desired track, of agricultural machines or implements A01B69/00; wheels, castors, axles, increasing wheel adhesion B60B; vehicle tyres, tyre inflation or tyre changing B60C; connections between vehicles of a train or the like B60D; vehicles for use on rail and road, amphibious or convertible vehicles B60F; suspension arrangements B60G; heating, cooling, ventilating or other air treating devices B60H; windows, windscreens, non-fixed roofs, doors or similar devices, protective coverings for vehicles not in use B60J; propulsion plant arrangements, auxiliary drives, transmissions, controls, instrumentation or dashboards B60K; electric equipment or propulsion of electrically-propelled vehicles B60L; power supply for electrically-propelled vehicles B60M; passenger accommodation not otherwise provided for B60N; adaptations for load transportation or to carry special loads or objects B60P; arrangement of signalling or lighting devices, the mounting or supporting thereof or circuits therefor, for vehicles in general B60Q; vehicles, vehicle fittings or vehicle parts not otherwise provided for B60R; servicing, cleaning, repairing, supporting, lifting, or manoeuvring, not otherwise provided for, B60S; brake arrangements, brake control systems or parts thereof B60T; air-cushion vehicles B60V; motor-cycles, accessories therefor B62J, B62K; testing of vehicles G01M)
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G07C: TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE

## Abstract

A number of illustrative variations may include a method for use in a vehicle having an electronic steering system, a position control module, an electronic steering system rack force observer, and a rack force observer vehicle diagnostic, wherein the method includes the steps of providing a vehicle that may include an electronic steering system, a position control module, an electronic steering system rack force observer, and a rack force observer vehicle diagnostic; measuring the steering angle and steering velocity of the vehicle; communicating a steering angle of the vehicle to the position control module and the electronic steering system rack force observer; communicating a steering velocity of the vehicle to the electronic steering system rack force observer; communicating electronic steering system motor commands to the electronic steering system rack force observer; and estimating rack force data and communicating the rack force data to the rack force observer vehicle diagnostic; and determining a compensated target steering angle.

## Claims

### Claim 1

A method for use in a vehicle having an electronic steering system, a position control module, an electronic steering system rack force observer, and a rack force observer vehicle diagnostic module, wherein the method comprising:
using the electronic steering system rack force observer to perform the acts of monitoring electric current inside the electronic steering system relative to an electric motor position, calculating rack force data on a steering rack using the monitored electric current inside the electronic steering system relative to an electric motor position, determining when the calculated rack force is unexpected;
receiving rack force data from the electronic steering system rack force observer;
receiving vehicle speed data from a wheel speed sensor module; vehicle state data from an inertial measurement unit module; vehicle network data from a brake system module; and positional data from a GPS module;
analyzing rack force data from the electronic steering system rack force observer; the vehicle speed data from the wheel speed sensor modules; the vehicle state data from the inertial measurement unit module; the vehicle network data from the brake system module; and the positional data from the GPS module;
calculating steering offset diagnostic data by measuring at least one of a steering angle or a steering velocity of the vehicle relative to at least one of a straight position;
communicating the calculated steering offset diagnostic data to a motion control module;
receiving the steering offset diagnostic data from the rack force observer vehicle diagnostic module; and
calculating a compensated target steering angle based on rack force data relative to the straight position of the steering angle to account for sudden changes in rack forces, and adjusting the steering angle of the vehicle based on the calculated compensated target steering angle when the calculated rack force is unexpected based upon the measured steering angle.

### Claim 2 (depends on 1)

The method as set forth in claim 1, further comprising: communicating the positional data to the motion control module prior to calculating the compensated target steering angle.

### Claim 3 (depends on 2)

The method as set forth in claim 2, further comprising: communicating the calculated compensated target steering angle to the position control module.

### Claim 4 (depends on 3)

The method as set forth in claim 3, further comprising: adjusting the steering angle of the vehicle.

### Claim 5 (depends on 1)

The method as set forth in claim 1, further comprising: signaling to a user that maintenance of the vehicle is required.

### Claim 6 (depends on 1)

The method as set forth in claim 1, further comprising: signaling to a user that adjusting driving trajectory or speed is required.

### Claim 7 (depends on 1)

A method as in claim 1, further comprising:
analyzing environmental condition data; and
adjusting the calculated compensated target steering angle based on both the rack force data and the environmental condition data to account for changes in road surface or weather conditions.

### Claim 8 (depends on 1)

The method as in claim 1, further comprising:
storing historical rack force data and corresponding steering compensation values; and
using the stored historical rack force data to update a predictive model that estimates future rack force anomalies to improve compensated target steering angle calculation.

### Claim 9 (depends on 1)

The method as in claim 1, further comprising: detecting lateral acceleration exceeding a predetermined threshold; and in response to the threshold being exceeded, modifying the frequency of rack force monitoring to increase sample rate.

### Claim 10 (depends on 1)

The method as in claim 1, further comprising:
verifying that the calculated rack force is unexpected by comparing with other sensor data to confirm the presence of a disturbance.

### Claim 11

An electronic power steering system comprising: a steering rack;
at least one wheel;
a brake system module;
a wheel speed sensor module;
an inertial measurement unit module; a position control module;
a motion control module; a GPS module;
an electronic steering system rack force observer;
a rack force observer vehicle diagnostic module;
at least one computing device;
memory that stores computer-executable components;
a processor that executes the computer-executable components stored in the memory, wherein the computer-executable components when executed by the processor cause the acts of:
receiving and analyzing rack force data from the electronic steering system rack force observer; vehicle speed data from the wheel speed sensor module; vehicle state data from the inertial measurement unit module; vehicle network data from the brake system module; and positional data from the GPS module;
using the electronic steering system rack force observer to perform the acts of monitoring electric current inside the electronic steering system relative to an electric motor position, calculating rack force data on a steering rack using the monitored electric current inside the electronic steering system relative to an electric motor position, determining when the calculated rack force is unexpected;
calculating steering offset diagnostic data by measuring at least one of a steering angle or a steering velocity of the vehicle relative to a straight position, vehicle speed data from the wheel speed sensor module, vehicle state data from the inertial measurement unit module, vehicle network data from the brake system module, or position data from the GPS module;
communicating the steering offset diagnostic data to the motion control module;
calculating a compensated target steering angle based on rack force data relative to the straight position of the steering angle to account for sudden changes in rack forces;
communicating the calculated compensated target steering angle to the position control module; and
adjusting the steering angle of the at least one wheel based on the calculated compensated target steering angle when the calculated rack force data is unexpected based upon the measured steering angle.

### Claim 12 (depends on 11)

The electronic power steering system as set forth in claim 11 wherein the acts further comprise communicating the positional data to the motion control module prior to calculating the compensated target steering angle.

### Claim 13 (depends on 11)

The electronic power steering system as set forth in claim 11, wherein the acts further comprise signaling to a user that maintenance of the vehicle is required.

### Claim 14 (depends on 11)

The electronic power steering system as set forth in claim 11, wherein the acts further comprise signaling to a user that adjusting driving trajectory or speed is required.

### Claim 15 (depends on 11)

An electronic power steering system as in claim 11, wherein the processor is further configured to:
classify a type of rack force disturbance using a disturbance classification module based on pattern recognition of steering rack forces, and
select a steering compensation strategy from a predefined set based on the classified disturbance type.

### Claim 16

An electronic power steering system comprising: a steering rack;
at least one wheel;
a brake system module;
a wheel speed sensor module;
an inertial measurement unit module;
a position control module;
a motion control module; a GPS module;
an electronic steering system rack force observer;
a rack force observer vehicle diagnostic module;
at least one computing device;
memory that stores computer-executable components;
a processor that executes the computer-executable components stored in the memory, wherein the computer-executable components when executed by the processor cause the acts of:
receiving and analyzing rack force data from the electronic steering system rack force observer; vehicle speed data from the wheel speed sensor module; vehicle state data from the inertial measurement unit module; vehicle network data from the brake system module; and positional data from the GPS module;
using the electronic steering system rack force observer to perform the acts of monitoring electric current inside the electronic steering system relative to an electric motor position, calculating rack force data on a steering rack using the monitored electric current inside the electronic steering system relative to an electric motor position, determining when the calculated rack force is unexpected;
calculating steering offset diagnostic data by measuring at least one of a steering angle or a steering velocity of the vehicle relative to at least one of a straight position, vehicle speed data from the wheel speed sensor module, vehicle state data from the inertial measurement unit module, vehicle network data from the brake system module, or position data from the GPS module;
communicating the steering offset diagnostic data to the motion control module;
receiving the steering offset diagnostic data from the rack force observer vehicle diagnostic module;
calculating a compensated target steering angle based on rack force data relative to the straight position of the steering angle to account for sudden changes in rack forces;
communicating the calculated compensated target steering angle to the position control module; and
adjusting the steering angle of the at least one wheel based on the calculated compensated target steering angle when the rack force data is unexpected based upon the measured steering angle.