Electric power steering mode determination and transitioning

• US 10,363,958 B2
• Filed: 07/21/2017
• Issued: 07/30/2019
• Est. Priority Date: 07/26/2016
• 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: Otto, Jeffrey M., Ramanujam, Rangarajan, Sainath, Bhuvanesh
• Primary Examiner(s): Lee, Tyler J
• Application Number:
  US15/656,075
• Publication Number:
  US 20180029640A1
• Time in Patent Office: 739 Days
• CPC Class Codes: B62D 1/286 Systems for interrupting non-mechanical steering due to driver intervention
• 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 6/007 adjustable by the driver, e.g. sport mode
• CPC Class Codes: B62D 6/08 responsive only to driver input torque
• CPC Class Codes: G05D 1/021 specially adapted to land vehicles

Abstract

Technical solutions are described for facilitating an electric power steering (EPS) system to determine an operating mode of a vehicle that is equipped with the EPS, where the operating mode is indicative of a level of autonomous driving being used by the vehicle. The technical solutions further facilitate detecting a change in the operating mode of the vehicle, and facilitating a transition in computing an assist signal for the EPS system during the transition between the operating modes.

Claims

1. An electric power steering system comprising:

an advance driver assist module configured to;

determine an operation mode that indicates a level of autonomous driving, the operation mode being a first operation mode from a plurality of levels of autonomous driving comprising at least a fully automated operation mode, a semi-automated operation mode, and a non-automated operation mode;

detect a change from the first operation mode to a second operation mode; and

transition performance of the electric power steering system from the first operation mode to the second operation mode, the transitioning comprising;

determining a blend factor for adjusting the performance of the electric power steering system that is operating using a first calibration factor of the first operation mode to a second calibration factor of the second operation mode, the blend factor based on a vehicle speed;

scaling the second calibration factor using the blend factor; and

generating a steering system command using the scaled second calibration factor.

2. The electric power steering system of claim 1, wherein determining the operation mode is based on an amount of intervening handwheel torque measured during operation.

3. The electric power steering system of claim 1, wherein detecting the change from the first operation mode to the second operation mode is based on a change in a vehicle configuration, and an amount of intervening handwheel torque, at a vehicle speed that is below a predetermined speed threshold.

4. The electric power steering system of claim 1, further comprising a control module configured to generate the steering system command, which comprises a motor torque command using the scaled second calibration factor.

5. The electric power steering system of claim 1, wherein transitioning the performance comprises:

switching off an EPS function.

6. The electric power steering system of claim 1, wherein the first operation mode is one of a human operator mode or a hybrid mode and the second operation mode is an autonomous mode.

7. The electric power steering system of claim 1, wherein the first operation mode is a human operator mode and the second operation mode is a hybrid mode.

8. The electric power steering system of claim 1, wherein the first operation mode is a hybrid mode and the second operation mode is a human operator mode.

9. The electric power steering system of claim 1, wherein transitioning the performance comprises:

setting a value of a transition-complete flag based on the blend factor, the transition-complete flag being set to TRUE based on the blend factor exceeding a maximum threshold, and set to FALSE otherwise.

10. An advance driver assist module for an electric power steering system, which is configured to:

determine an operation mode that indicates a level of autonomous driving, the operation mode being a first operation mode from a plurality of levels of autonomous driving comprising at least a fully automated operation mode, a semi-automated operation mode, and a non-automated operation mode;

detect a change from the first operation mode to a second operation mode; and

transition performance of the electric power steering system from the first operation mode to the second operation mode, the transitioning comprising;

determining a blend factor for adjusting the performance of the electric power steering system that is operating using a first calibration factor of the first operation mode to a second calibration factor of the second operation mode, the blend factor based on a vehicle speed;

scaling the second calibration factor using the blend factor; and

generating a steering system command using the scaled second calibration factor.

11. The advance driver assist module of claim 10, wherein determining the operation mode is based on an amount of handwheel torque.

12. The advance driver assist module of claim 10, wherein detecting the change from the first operation mode to the second operation mode is based on a change in a vehicle configuration, and an amount of handwheel torque, at a vehicle speed that is below a predetermined speed threshold.

13. The advance driver assist module of claim 10, wherein detecting the change from the first operation mode to the second operation mode is based on a request to switch to the second operation mode.

14. The advance driver assist module of claim 10, further comprising a control module configured to generate the steering system command, which comprises a motor torque command using the scaled second calibration factor.

15. A method for providing assist signal to an electric power steering system, the method comprising:

determining an operation mode of the electric power steering system, the operation mode indicates a level of autonomous driving of a vehicle equipped with the electric power steering system, the operation mode being a first operation mode from a plurality of levels of autonomous driving comprising at least a fully automated operation mode, a semi-automated operation mode, and a non-automated operation mode;

detecting a change from the first operation mode to a second operation mode; and

transitioning performance of the electric power steering system from the first operation mode to the second operation mode, the transitioning comprising;

determining a blend factor for adjusting the performance of the electric power steering system that is operating using a first calibration factor of the first operation mode to a second calibration factor of the second operation mode, the blend factor based on a vehicle speed;

scaling the second calibration factor using the blend factor; and

generating a steering system command using the scaled second calibration factor.

16. The method of claim 15, wherein determining the operation mode is based on an amount of handwheel torque.

17. The method of claim 15, wherein detecting the change from the first operation mode to the second operation mode is based on a change in a vehicle configuration, and an amount of handwheel torque, at a vehicle speed that is below a predetermined speed threshold.

18. The method of claim 15, further comprising:

in response to receiving a sensor failure indication, bypassing a fault response associated with the sensor failure in response to the electric power steering system being operated in the first operation mode, which is an autonomous mode.