# US 11,897,555 B2 · Steering control device

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- Number: US 11,897,555 B2
- Document ID: US11897555B2
- Status: Granted
- Kind: B2
- Application number: 17/017,828
- Filed: 2020-09-11
- Published: 2021-03-18
- Granted: 2024-02-13
- Earliest claimed: 2019-09-13
- Assignees: Jtekt Corporation
- Applicants: Jtekt Corporation
- Inventors: Takahiro Toko; Nobuaki Kataoka; Takafumi Yamaguchi; Yukinobu Ezaki
- Web page: https://patentgrep.com/patent/US11897555B2

## CPC

- B62D 5/0463: {calculating assisting torque from the motor based on driver input}
- B62D 5/0469: {End-of-stroke control}
- B62D 5/0409: {Electric motor acting on the steering column}
- B62D 15/0235: {by measuring or deriving directly at the electric power steering motor}
- B62D 5/0454: {Worm gears}
- B62D 5/0466: {for returning the steering wheel to neutral position}
- 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)

## Abstract

A steering control device includes an electronic control unit. The electronic control unit is configured to detect an absolute steering angle, to calculate a current command value, to control driving of a motor such that an actual current value which is supplied to the motor reaches the current command value, to store an end-position-corresponding angle which is correlated with the absolute steering angle, to perform end contact relaxation control for correcting the current command value such that a decrease of an end separation angle is regulated when the end separation angle is equal to or less than a predetermined angle, and to calculate the current command value such that an increase of the end separation angle is not regulated by the end contact relaxation control when the end separation angle is equal to or less than the predetermined angle.

## Claims

### Claim 1

A steering control device that controls a steering system including a housing, a turning shaft which is accommodated in the housing to reciprocate, and an actuator which applies a motor torque for turning wheels connected the turning shaft using a motor as a drive source, the steering control device comprising:
an electronic control unit,
wherein the electronic control unit is configured to:
detect an absolute steering angle which is a rotation angle of a rotation shaft which is able to be converted into a turning angle of the turning wheels and which is expressed as an absolute angle including a range greater than 360°;
calculate a current command value corresponding to a target value of the motor torque which is output from the motor;
control driving of the motor such that an actual current value which is supplied to the motor reaches the current command value;
store an end-position-corresponding angle which is an angle indicating an end position at which movement of the turning shaft is regulated by an end contact of the turning shaft coming into contact with the housing and which is correlated with the absolute steering angle;
perform end contact relaxation control for correcting the current command value such that a decrease of an end separation angle indicating a distance of the absolute steering angle from the end-position-corresponding angle is regulated when the end separation angle is equal to or less than a predetermined angle;
calculate the current command value such that an increase of the end separation angle is not regulated by the end contact relaxation control when the end separation angle is equal to or less than the predetermined angle,
calculate a steering angle limit value which decreases based on a decrease of the end separation angle when the end separation angle is equal to or less than the predetermined angle;
perform the end contact relaxation control by limiting the absolute value of the current command value to the steering angle limit value;
calculate an angle limiting component which increases based on the decrease of the end separation angle when the end separation angle is equal to or less than the predetermined angle;
calculate the steering angle limit value based on a pre-adjustment steering angle limit value which is obtained by subtracting the angle limiting component from a rated current of the motor; and
set the absolute value of the steering angle limit value to the rated current when the end separation angle is equal to or less than the predetermined angle and the end separation angle increases.

### Claim 2 (depends on 1)

The steering control device according to claim 1, wherein: when the sign of the current command value for causing the motor to generate the motor torque for turning the turning wheels to one side of right and left sides is defined as being positive and the sign of the current command value for causing the motor to generate the motor torque for turning the turning wheels to the other side is defined as being negative,
the electronic control unit is configured to set the absolute value of the steering angle limit value to the rated current when the turning wheels are turned to the one side, the end separation angle is equal to or less than the predetermined angle, and the current command value before being corrected is less than a positive pre-adjustment steering angle limit value and to set the absolute value of the steering angle limit value to the pre-adjustment steering angle limit value when the turning wheels are turned to the one side, the end separation angle is equal to or less than the predetermined angle, and the current command value before being corrected is equal to or greater than the positive pre-adjustment steering angle limit value; and
the electronic control unit is configured to set the absolute value of the steering angle limit value to the rated current when the turning wheels are turned to the other side, the end separation angle is equal to or less than the predetermined angle, and the current command value before being corrected is greater than a negative pre-adjustment steering angle limit value and to set the absolute value of the steering angle limit value to the pre-adjustment steering angle limit value when the turning wheels are turned to the other side, the end separation angle is equal to or less than the predetermined angle, and the current command value before being corrected is equal to or less than the negative pre-adjustment steering angle limit value.

### Claim 3 (depends on 2)

The steering control device according to claim 2, wherein the electronic control unit is configured to:
compare a one-side end separation angle indicating a distance of the absolute steering angle from the end-position-corresponding angle on the one side and an other-side end separation angle indicating a distance of the absolute steering angle from the end-position-corresponding angle on the other side with a preset end separation angle threshold value;
determine that the turning wheels are turned to the one side when the absolute value of the one-side end separation angle is less than the end separation angle threshold value; and
determine that the turning wheels are turned to the other side when the absolute value of the other-side end separation angle is less than the end separation angle threshold value.