Vehicle with independently driven multiple axes, and controller which independently drives multiple axles

Patent metadata

Field	Value
Publication number	US-9950703-B2
Application number	US-201414312280-A
Country	US
Kind code	B2
Filing date	Jun 23, 2014
Priority date	Nov 2, 2010
Publication date	Apr 24, 2018
Grant date	Apr 24, 2018

Abstract

A vehicle with independently driven multiple axles and a controller which independently drives the multiple axles are disclosed. The controller includes a first controller which determines a target control value including at least one of a mechanical steering angle of each of a plurality of wheels of a vehicle, a target yaw moment of the vehicle, a target longitudinal force of the vehicle, and a target wheel speed of each of the plurality of wheels; and a second controller which determines wheel torques of the plurality of wheels, which drive the plurality of wheels independently, based on the target control value, wherein the wheel torques of the plurality of wheels are different from one another.

First claim

What is claimed is:

1. A vehicle with independently driven multiple axles, the vehicle comprising:
a plurality of wheels;
an operation input unit which receives an operation input comprising at least one of a steering input, an acceleration input, and a braking input;
a first controller which determines a target control value comprising at least one of a mechanical steering angle of each of the plurality of wheels, a target yaw moment of the vehicle, a target longitudinal force of the vehicle, and a target wheel speed of each of the plurality of wheels, from the operation input, according to a driving condition of the vehicle; and
a second controller which determines wheel torques of the plurality of wheels, which drive the plurality of wheels independently, based on the target control value,
wherein the operation input comprises the steering input,
wherein the first controller receives the steering input and a target speed of the vehicle and determines the mechanical steering angle of each of the plurality of wheels, the target yaw moment of the vehicle, and the target longitudinal force of the vehicle, and
wherein, for a wheel torque control, the second controller determines a tire force of each of the plurality of wheels by receiving the target longitudinal force of the vehicle and the target yaw moment of the vehicle, and distributing the target longitudinal force of the vehicle and the target yaw moment of the vehicle as a force to be exerted at a bottom of a tire of each of the plurality of wheels, and determines the wheel torques of the plurality of wheels by wheel slip control from the tire force of each of the plurality of wheels.

2. The vehicle of claim 1 , wherein the wheel torques of the plurality of wheels, which drive the plurality of wheels independently, are different from one another.

3. The vehicle of claim 1 , further comprising:
motors which drive the plurality of wheels through the wheel torques, respectively;
a plurality of brakes which are installed on the plurality of wheels, respectively; and
a steering means which is linked to at least one of the plurality of wheels and adjusts a steering angle of the at least one of the plurality of wheels.

4. The vehicle of claim 3 , wherein the driving condition comprises at least one of:
a normal driving mode in which the vehicle is controlled by at least one of mechanical steering, complex braking, stability control, and slip control, wherein the mechanical steering is performed by the steering means to adjust the steering angle, and the complex braking comprises regenerative braking generated by the motors and braking generated by the plurality of brakes;
a quick turning driving mode in which the vehicle is controlled by at least one of complex steering, the complex braking, the stability control, and the slip control, wherein the complex steering comprises the mechanical steering and wheel torque steering; and
a pivot turning mode in which the vehicle is controlled by the complex steering, wherein the complex steering for the pivot turning mode does not include the mechanical steering.

5. The vehicle of claim 4 , wherein the vehicle is controlled by a steering control program comprising at least one of the mechanical steering, the stability control, the wheel torque control, and wheel speed control according to a driving situation.

6. The vehicle of claim 5 , wherein the driving situation is determined by at least one of a speed of the vehicle and a condition of a road on which the vehicle is driven.

7. The vehicle of claim 1 , wherein the first controller determines:
the mechanical steering angle of each of the plurality of wheels from the steering input;
a target yaw rate of the vehicle from the mechanical steering angle of each of the plurality of wheels in consideration of a time delay; and
the target yaw moment of the vehicle by feeding back a measured yaw rate of the vehicle to the target yaw rate of the vehicle to perform yaw rate control.

8. The vehicle of claim 7 , wherein for the yaw rate control, the target yaw moment of the vehicle is determined by a sliding control method in which a difference between the measured yaw rate of the vehicle and the target yaw rate of the vehicle is converged to 0 by enabling a differential coefficient of the difference relative to time to always have a sign opposite to that of the difference.

9. The vehicle of claim 7 , wherein the first controller determines the target longitudinal force of the vehicle using a Proportional Integral Derivative (PID) control method based on difference between the target speed of the vehicle and a measured speed of the vehicle.

10. The vehicle of claim 1 , wherein the vehicle is a type of a 4-wheel vehicle, a 6-wheel vehicle, or an 8-wheel vehicle, and the target yaw moment is determined according to the type of the vehicle.

11. The vehicle of claim 1 , wherein a friction circle is determined from a maximum force which is generated in each of the plurality of wheels according to a driving situation, and the tire force is determined in proportion to a size of the friction circle.

12. The vehicle of claim 11 , wherein the tire force of each of the plurality of wheels is determined by using optimal distribution of force using a performance index proportional to the size of the friction circle.

13. The vehicle of claim 12 , wherein a friction force of each of the plurality of wheels is estimated and input, and the performance index proportional to the size of the friction circle is obtained.

14. The vehicle of claim 13 , wherein the size of the friction circle is estimated from a linear function having a linear relationship between a slip ratio and a longitudinal tire force as an input, the linear relationship being configured to minimize a difference between a first longitudinal tire force and a second longitudinal tire force,
wherein the first longitudinal tire force is determined by applying a slip ratio, which is estimated based on a wheel speed and a vehicle speed, to the linear relationship between the slip ratio and the longitudinal tire force, and
wherein the second longitudinal tire force is estimated based on a wheel torque and a wheel angular acceleration that is obtained from the wheel speed.

15. The vehicle of claim 14 , wherein the linear relationship between the slip ratio and the longitudinal tire force is configured such that the difference is minimized using a Recursive Least Square method.

16. The vehicle of claim 14 , further comprising a vehicle speed estimator configured to:
estimate a first vehicle speed based on a vehicle yaw rate and wheel speed of wheels having the wheel angular acceleration equal to or less than a threshold,
estimate a second vehicle speed based on a longitudinal vehicle acceleration, and
estimate the vehicle speed by adding the first vehicle speed and the second vehicle speed.

17. The vehicle of claim 1 , wherein if the first controller determines the target wheel speed of each of the plurality of wheels, the target wheel speed of each of the plurality of wheels is calculated by reflecting a slip ratio of each of the plurality of wheels, a difference between the target wheel speed of each of the plurality of wheels and a wheel speed of each of the plurality of wheels is defined as a sliding surface, and each of the wheel torques is determined by inserting a state condition for converging the sliding surface to 0 into a wheel torque equation of each of the plurality of wheels.

18. The vehicle of claim 17 , wherein if the slip ratio of each of the plurality o

Assignees

• Samsung Techwin Co Ltd
• Snu R&Db Foundation
• Hanwha Land Sys Co Ltd

Inventors

• Lee Jong-Seok
• Yi Kyoung-Su
• Kim Won-Gun
• Joung Soung-Yong

Classifications

• B60W30/18172

  Preventing, or responsive to skidding of wheels · CPC title

• B60W10/04

  including control of propulsion units · CPC title

• B60W2720/14

  Yaw · CPC title

• B60W2710/207

  Steering angle of wheels · CPC title

• B60W10/18

  including control of braking systems · CPC title