# US 2023/0406409 A1 · Apparatus, method and computer readable medium for calculating target steering angle considering yaw moment by torque vectoring when turning driving of electric vehicle in autonomous driving

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- Number: US 2023/0406409 A1
- Document ID: US20230406409A1
- Status: Published application
- Kind: A1
- Application number: 17/955,288
- Filed: 2022-09-28
- Published: 2023-12-21
- Earliest claimed: 2022-06-21
- Assignees: Hyundai Motor Company; Kia Corporation
- Applicants: Hyundai Motor Company; Kia Corporation
- Inventors: Gwi Chul KIM
- Web page: https://patentgrep.com/patent/US20230406409A1

## CPC

- B62D 6/003: {in order to control vehicle yaw movement, i.e. around a vertical axis (B62D6/007 takes precedence)}
- B62D 15/021: {Determination of steering angle}
- B60W 10/20: including control of steering systems
- B60W 40/101: Side slip angle of tyre
- B60W 40/109: Lateral acceleration
- B60W 40/114: Yaw movement
- B60W 40/13: Load or weight
- B60W 50/0098: {Details of control systems ensuring comfort, safety or stability not otherwise provided for}
- B60W 60/001: {Planning or execution of driving tasks}
- B60W 2040/1315: {Location of the centre of gravity}
- B60W 2050/0008: {Feedback, closed loop systems or details of feedback error signal}
- B60W 2050/0012: {Feedforward or open loop systems}
- B60W 2510/083: Torque
- B60W 2510/222: Stiffness
- B60W 2520/125: Lateral acceleration
- B60W 2520/14: Yaw
- B60W 2520/263: Slip values between front and rear axle
- B60W 2540/18: Steering angle
- 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)
- B60W: CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT

## Abstract

An apparatus of determining a target steering angle, may include: a feedforward steering angle calculator configured for determining a feed forward steering angle reflecting a yaw moment generated by torque vectoring during turning driving of an electric vehicle in autonomous driving; and an adder configured for obtaining a target steering angle by adding the determined feedforward steering angle to a feedback steering angle, the feedback steering angle being a steering angle measured through a steering angle sensor.

## Claims

### Claim 1

An apparatus of determining a target steering angle, the apparatus comprising:
a feedforward steering angle calculator configured for determining a feed forward steering angle reflecting a yaw moment generated by torque vectoring during turning driving of an electric vehicle in autonomous driving; and
an adder configured for obtaining the target steering angle by adding the determined feedforward steering angle to a feedback steering angle, the feedback steering angle being a steering angle measured through a steering angle sensor.

### Claim 2 (depends on 1)

The apparatus of claim 1, wherein the feedforward steering angle calculator is configured to:
obtain the yaw moment generated by the torque vectoring during the turning driving of the electric vehicle,
obtain lateral force of a tire of each of a front wheel and a rear wheel of the electric vehicle by reflecting the obtained yaw moment,
obtain a tire slip angle of each of the front wheel and the rear wheel based on the obtained lateral force of the tire of each of the front wheel and the rear wheel, and
obtain the feedforward steering angle based on the obtained tire slip angle of each of the front wheel and the rear wheel.

### Claim 3 (depends on 2)

The apparatus of claim 2, wherein the yaw moment is expressed by the following equation :
MzTV={(TFR+TRR−(TFL+TRL)}w/r
where, MZ,TV is a yaw moment, TFR is a torque applied to a motor on a right side of the front wheel by the torque vectoring, TRR is a torque applied to a motor on a right side of the rear wheel by the torque vectoring, TFL is a torque applied to a motor on a left side of the front wheel by the torque vectoring, TRL is a torque applied to a motor on a right side of the rear wheel by the torque vectoring, w is a lateral distance from center of gravity (CG) to the wheel, and r is a dynamic radius of the tire.

### Claim 4 (depends on 2)

The apparatus of claim 2, wherein the lateral force of the tire is expressed by the following equation:
F
y
,
F
=
ma
y
⁢
I
R
l
-
M
Z
,
TV
l
F
y
,
R
=
ma
y
⁢
I
F
l
-
M
Z
,
TV
l
where, Fy,F is lateral force of the tire of the front wheel, Fy,R is lateral force of the tire of the rear wheel, m is mass of the electric vehicle, ay is lateral acceleration, IR is a length from center of gravity of the electric vehicle to the rear wheel, l is an inter-axle distance, MZ,TV is a yaw moment, and when is a length from the center of gravity of the electric vehicle to the front wheel.

### Claim 5 (depends on 2)

The apparatus of claim 2, wherein the tire slip angle is expressed by the following equation:
α
F
=
F
y
,
F
C
a
,
F
α
R
=
F
y
,
R
C
a
,
R
where, αF is the tire slip angle of the front wheel, Fy,F is lateral force of the tire of the front wheel, Cα,F is tire stiffness of the front wheel, αR is a tire slip angle of the rear wheel, Fy,R is lateral force of the tire of the rear wheel, and Cα,R is tire stiffness of the rear wheel.

### Claim 6 (depends on 2)

The apparatus of claim 2, wherein the feedforward steering angle is expressed by the following equation:
δFF=lκref−(αF−αR)
where, δFF is a feedforward steering angle, l is a length between the front wheel and the rear wheel, kref is 1/(R*cos β), where, R is a turning radius, β is a lateral slip angle at center of gravity, αF is a tire slip angle of the front wheel, and αR is a tire slip angle of the rear wheel.

### Claim 7

A method for determining a target steering angle, the method comprising:
determining, by a processor, a feedforward steering angle by reflecting a yaw moment generated by torque vectoring during turning driving of an electric vehicle in autonomous driving; and
obtaining, by the processor, a target steering angle by adding the determined feedforward steering angle to a feedback steering angle, the feedback steering angle being a steering angle measured through a steering angle sensor.

### Claim 8 (depends on 7)

The method of claim 7, wherein the determining a feedforward steering angle includes:
obtaining the yaw moment generated by the torque vectoring during turning driving of the electric vehicle;
obtaining lateral force of a tire each of a front wheel and a rear wheel by reflecting the obtained yaw moment;
obtaining a tire slip angle each of the front wheel and the rear wheel based on the obtained lateral force of the tire of each of the front wheel and the rear wheel; and
obtaining the feedforward steering angle based on the obtained tire slip angle of each of the front wheel and the rear wheel.

### Claim 9 (depends on 8)

The method of claim 8, wherein the yaw moment is expressed by the following equation:
MzTV={(TFR+TRR−(TFL+TRL)}w/r
where, MZ,TV is a yaw moment, TFR is a torque applied to a motor on a right side of the front wheel by the torque vectoring, TRR is a torque applied to a motor on a right side of the rear wheel by the torque vectoring, TFL is a torque applied to a motor on a left side of the front wheel by the torque vectoring, TRL is a torque applied to a motor on a right side of the rear wheel by the torque vectoring, w is a lateral distance from center of gravity (CG) to the wheel, and r is a dynamic radius of the tire.

### Claim 10

The method of claim , wherein the lateral force of the tire is expressed by the following equation:
F
y
,
F
=
ma
y
⁢
I
R
l
-
M
Z
,
TV
l
F
y
,
R
=
ma
y
⁢
I
F
l
-
M
Z
,
TV
l
where Fy,F is lateral force of a tire of the front wheel, Fy,R is lateral force of a tire of the rear wheel, m is mass of the electric vehicle, ay is lateral acceleration, IR is a length from center of gravity of the electric vehicle to the rear wheel, l is an inter-axle distance, MZ,TV is a yaw moment, and IF is a length from the center of gravity of the electric vehicle to the front wheel.

### Claim 11 (depends on 8)

The method of claim 8, wherein the tire slip angle is expressed by the following equation:
α
F
=
F
y
,
F
C
a
,
F
α
R
=
F
y
,
R
C
a
,
R
where, αF is a tire slip angle of the front wheel, Fy,F is lateral force of a tire of the front wheel, Cα,F is tire stiffness of the front wheel, αR is a tire slip angle of the rear wheel, Fy,R is lateral force of a tire of the rear wheel, and Cα,R is tire stiffness of the rear wheel.

### Claim 12 (depends on 8)

The method of claim 8, wherein the feedforward steering angle is expressed by the following equation:
δFF=lκref−(αF−αR)
where, δFF is a feedforward steering angle, l is a length between a front wheel and a rear wheel, kref is 1/(R*cos β), where, R is a turning radius, β is a lateral slip angle at center of gravity, αF is a tire slip angle of the front wheel, and αR is a tire slip angle of the rear wheel.

### Claim 13 (depends on 7)

A non-transitory computer-readable storage medium in which a program for executing the method of claim 7 by the processor is recorded.