SYSTEM FOR PROVIDING ASSIST TORQUE BASED ON A VEHICLE STATE

• US 20140277945A1
• Filed: 03/12/2013
• Published: 09/18/2014
• Est. Priority Date: 03/12/2013
• Status: Active Grant

• Current Assignee: Steering Solutions IP Holding Corporation (Nexteer Automotive Group Ltd.)
• Original Assignee: Steering Solutions IP Holding Corporation (Nexteer Automotive Group Ltd.)
• Inventors: Chandy, Ashok
• Granted Patent: US 8,903,610 B2
• Time in Patent Office: Days
• US Class Current: 701/42
• CPC Class Codes: B62D 15/025 Active steering aids, e.g. helping the driver by actively influencing the steering system after environment evaluation B62D1/28 takes precedence
• CPC Class Codes: B62D 5/0463 calculating assisting torque from the motor based on driver input
• CPC Class Codes: B62D 6/00 Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits means for initiating a change in direction B62D1/00; steering valves B62D5/06; combined with means for inclining the vehicle body or wheels on bends B62D9/00

Abstract

A control system for providing an assist torque is provided. The control system includes a control algorithm module and a comfort limit module. The control algorithm module calculates a corrective steering torque based on a target vehicle state and an estimated vehicle state. The comfort limit module receives a handwheel torque. The comfort limit module calculates a limited corrective steering torque based on the corrective steering torque and the handwheel torque. The limited steering torque represents an allowable amount of the assist torque provided by the control system.

Claims

1. A control system for providing an assist torque, comprising:

a control algorithm module that calculates a corrective steering torque based on a target vehicle state and an estimated vehicle state; and

a comfort limit module receiving a handwheel torque, the comfort limit module calculating a limited corrective steering torque based on the corrective steering torque and the handwheel torque, the limited steering torque representing an allowable amount of the assist torque provided by the control system.

2. The control system as recited in claim 1, wherein the comfort limit module determines an allowable handwheel torque deviation based on the handwheel torque.

3. The control system as recited in claim 2, wherein the allowable handwheel torque deviation is used to determine an upper limit for corrective steering torque and a lower limit for corrective steering torque, wherein the upper limit for corrective steering torque is calculated based on an upper limit assist table and the lower limit for corrective steering torque is calculated based on a lower limit assist table.

4. The control system as recited in claim 1, comprising a lane driving assist module for determining the target vehicle state, and wherein the target vehicle state includes a target heading angle Φ

_target, and a target lateral position Δ

y_target.

5. The control system as recited in claim 1, comprising a coordination limit module for determining a coordination torque, wherein the coordination torque represents a higher value of one of the limited corrective steering torque and a steering assist torque with respect to a direction of the limited corrective steering torque.

6. The control system as recited in claim 5, wherein the coordination torque is expressed by the following equation:

T_coor=Sign(Tik_lim)*max(sign(Tlk_lim)*T_o,|Tlk|)*sign(Tlk_lim)−

T_o

wherein Tlk_lim is the limited corrective steering torque and T_o is the steering assist torque, and wherein sign(Tlk_lim)=1 for Tlk_lim≧

0;

−

1 for Tlk_lim<

0.

7. The control system as recited in claim 5, wherein a total amount of torque is determined by summing the steering assist torque and the coordination torque together.

8. The control system as recited in claim 1, comprising an estimation module that calculates an estimated heading angle and a relative lateral position, wherein the estimated heading angle and the relative lateral position of the vehicle are based on the position of the vehicle with respect to the lane.

9. The control system as recited in claim 8, comprising a lane keeping system including a camera and processor in communication with the estimation module.

10. A control system for providing an assist torque, comprising:

a control algorithm module that calculates a corrective steering torque based on a target vehicle state and an estimated vehicle state; and

a coordination limit module receiving a steering assist torque, the coordination limit module for determining a coordination torque that represents a higher value of one of the corrective steering torque and the steering assist torque with respect to a direction of the limited corrective steering torque.

11. The control system as recited in claim 10, wherein the coordination torque is expressed by the following equation:

T_coor=sign(Tlk)*max(sign(Tlk)*To,|Tlk|)*sign(Tlk)−

To

wherein Tlk is the corrective steering torque and T_o is the steering assist torque, and

wherein sign(Tlk)=1 for Tlk≧

0;

−

1 for Tlk<

0.

12. The control system as recited in claim 10, wherein a total amount of torque is determined by summing the steering assist torque and the coordination torque together.

13. The control system as recited in claim 10, comprising an estimation module that calculates an estimated heading angle and a relative lateral position of the vehicle, wherein the estimated heading angle and the relative lateral position of the vehicle are based on the position of the vehicle with respect to the lane.

14. The control system as recited in claim 13, comprising a lane keeping system including a camera and processor in communication with the estimation module.

15. The control system as recited in claim 10, comprising a comfort limit module receiving a handwheel torque, the comfort limit module calculating a limited corrective steering torque based on the corrective steering torque and the handwheel torque, the limited steering torque representing an allowable amount of the corrective steering torque provided by the control system.

16. The control system as recited in claim 15, wherein the comfort limit module determines an allowable handwheel torque deviation based on the handwheel torque.

17. The control system as recited in claim 16, wherein the allowable handwheel torque deviation is used to determine an upper limit for corrective steering torque and a lower limit for corrective steering torque, wherein the upper limit for corrective steering torque is calculated based on an upper limit assist table and the lower limit for corrective steering torque is calculated based on a lower limit assist table.

18. The control system as recited in claim 10, comprising a lane driving assist module for determining the target vehicle state, and wherein the target vehicle state includes a target heading angle Φ

_target, and a target lateral position Δ

y_target.

19. A control system for providing an assist torque, comprising:

a control algorithm module that calculates a corrective steering torque based on a target vehicle state and an estimated vehicle state;

a comfort limit module receiving a handwheel torque, the comfort limit module calculating a limited corrective steering torque based on the corrective steering torque and the handwheel torque, the limited steering torque representing an allowable amount of the corrective steering torque provided by the control system; and

a coordination limit module receiving a steering assist torque, the coordination limit module for determining a coordination torque, wherein the coordination torque represents a higher value of one of the limited corrective steering torque and the steering assist torque with respect to a direction of the limited corrective steering torque.

20. The control system as recited in claim 19, wherein the coordination torque is expressed by the following equation:

T_coor=Sign(Tlk_lim)*max(sign(Tlk_lim)*T_o,|Tlk|)*sign(Tlk_lim)−

T_o

wherein Tlk_lim is the limited corrective steering torque and T_o is the steering assist torque, and wherein sign(Tlk_lim)=1 for Tlk_lim≧

0;

−

1 for (Tlk_lim)<

0.