GB2585318A

GB2585318A - Electric power steering torque compensation

Info

Publication number: GB2585318A
Application number: GB2017176.5A
Authority: GB
Inventors: Andersen Hans; Wu Ning; SECCAMONTE Francesco
Original assignee: Motional AD LLC
Current assignee: Motional AD LLC
Priority date: 2019-01-29
Filing date: 2020-01-29
Publication date: 2021-01-06
Anticipated expiration: 2040-01-29
Also published as: GB202017176D0; DK180545B1; CN112166068B; CN115071811A; KR102619281B1; KR20210110558A; GB2585318B; GB2604690A; GB202115652D0; KR102223836B1; KR20200133390A; DE112020000572T5; DK201970163A1; CN112166068A; GB2604690B

Abstract

Among other things, we describe techniques for electric power steering torque compensation. Techniques are provided for a method implemented by a computer, e.g., a computer onboard an autonomous vehicle (100). A planning circuit (404) onboard the vehicle (100) and connected to an Electric Power Steering (EPS) of the vehicle determines a compensatory torque signal to modify an actual steering angle of a steering wheel (1310) of the vehicle to match an expected steering angle of the steering wheel. The planning circuit transmits the compensatory torque signal to a control circuit (1102) that controls the steering angle of the steering wheel (1310). The EPS modifies the actual steering angle based on the compensatory torque signal resulting in a modified steering angle. The control circuit operates the vehicle based on the modified steering angle.

Claims

WHAT IS CLAIMED IS:

1. A computer-implemented method comprising: determining, by a planning circuit onboard a vehicle and connected to an electric power steering (EPS) system of the vehicle, a compensatory torque signal to modify an actual steering angle of a steering wheel of the vehicle to match an expected steering angle of the steering wheel; transmitting, by the planning circuit and to a control circuit, a base torque signal that applies a torque on the steering wheel; modifying the base torque signal in accordance with the compensatory torque signal, wherein at least one of the compensatory torque signal or the base torque signal is a voltage; transmitting, by the planning circuit, the compensatory torque signal to the control circuit that controls the steering angle of the steering wheel; modifying, by the EPS, the actual steering angle based on the compensatory torque signal resulting in a modified steering angle; and operating, using the control circuit, the vehicle based on the modified steering angle.

2. The method of claim 1, wherein modifying the base torque signal in accordance with the compensatory torque signal comprises adding a magnitude of the compensatory torque signal to a magnitude of the base torque signal.

3. The method of any of claims 1 or 2, wherein the compensatory torque signal is transmitted to the control circuit as a feedforward signal.

4. The method of any of claims 1 to 3, further comprising generating a plurality of compensatory torque signals, each generated compensatory torque signal comprising a respective torque signal to apply to the steering wheel.

5. The method of claim 4, wherein generating the plurality of compensatory torque signals comprises, for each generated compensatory torque signal: determining an expected steering angle of the steering wheel for the respective torque signal; applying the respective torque signal to the steering angle; operating the vehicle at the steering angle at a pre-determined speed; determining an actual steering angle of the steering wheel for the respective torque signal; and storing the generated compensatory torque signal and the actual steering angle as a data pair.

6. The method of any of claims 4 or 5, wherein determining the expected steering angle of the steering wheel for the respective torque signal comprises curve fitting a polynomial surface that relates vehicle speed and steering angle to applied torque.

7. The method of any of claims 1 to 6, further comprising: determining a difference between the expected steering angle and the actual steering angle; and in accordance with a determination that the difference exceeds a predetermined threshold, operating the vehicle to a target location.

8. The method of any of claims 1 to 7, further comprising: determining, by the planning circuit, operating conditions of the vehicle; and modifying the compensatory torque signal according to the operating conditions.

9. The method of claim 8, wherein the compensatory torque signal is modified according to the operating conditions in real-time.

10. The method of any of claims 8 to 9, wherein the operating conditions comprise weather conditions in which the vehicle is operated.

11. The method of any of claims 8 to 10, wherein the operating conditions comprise road conditions on which the vehicle is driven.

12. The method of any of claims 8 to 11, wherein the operating conditions comprise load carried by the vehicle.

13. The method of any of claims 8 to 12, wherein the operating conditions comprise driving conditions stored by the planning circuit in a passenger profile comprising driving preferences of one or more passengers of the vehicle.

14. The method of any of claims 8 to 13, further comprising receiving, by the planning circuit, an instruction to modify the compensatory torque signal from a remote location remote to the vehicle, wherein the compensatory torque signal is modified in response to receiving the instruction from the remote location.

15. A vehicle comprising: a planning circuit; memory; and at least one program stored in the memory, the at least one program including instructions executable by the planning circuit to perform the method of any one of claims 1-14.

16. A computer- readable storage medium comprising at least one program for execution by a planning circuit of a device, the at least one program including instructions which, when executed by the planning circuit, cause the vehicle to perform the method of any one of claims 1-14.