Parametric Remedial Action Strategy for an Active Front Steer System

• US 20080306654A1
• Filed: 06/07/2007
• Published: 12/11/2008
• Est. Priority Date: 06/07/2007
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations Incorporated (Motors Liquidation Co. GUC Trust)
• Inventors: Bolio, Robert R., Katrak, Kerfegar K.
• Granted Patent: US 8,170,750 B2
• Time in Patent Office: Days
• US Class Current: 701/41
• CPC Class Codes: B62D 5/008 Changing the transfer ratio between the steering wheel and the steering gear by variable supply of energy, e.g. by using a superposition gear
• CPC Class Codes: B62D 6/002 computing target steering angles for front or rear wheels B62D7/159 takes precedence

Abstract

A vehicle parametric active front steering (AFS) system remedial action is described herein. AFS system modules inter-communicate via messages containing parameters. The AFS system detects a message error, determines an invalid parameter, and takes appropriate remedial action. An error is detected if an error condition is satisfied or if occurrence of incorrect messages reaches or exceeds a certain predetermined frequency. The AFS system takes the remedial action by setting default values of valid parameters corresponding to the invalid parameter.

Claims

1. A method for parametric active front steer (AFS) remedial action for a vehicle, the method comprising:

detecting an error corresponding to an invalid parameter;

selecting a remedial action corresponding to the invalid parameter; and

taking the remedial action by setting valid parameters corresponding to the invalid parameter.

2. A method according to claim 1, further comprising monitoring AFS system messages for error occurrences.

3. A method according to claim 1, wherein the detecting step comprises detecting the error if:

a difference between a control path version and a redundant path version of a parameter is greater than or equal to a threshold;

an independent parameter is invalid for a dependent parameter;

a rolling count error occurs;

or

a checksum error occurs.

4. A method according to claim 1, wherein the detecting step comprises:

obtaining an incorrect message count; and

detecting the error if the incorrect message count is greater than or equal to a predetermined measure.

5. A method according to claim 4, wherein the predetermined measure comprises a number of consecutive incorrect messages.

6. A method according to claim 4, wherein the predetermined measure comprises X incorrect messages within Y consecutive messages, where Y is greater than or equal to X.

7. A method according to claim 4, wherein the predetermined measure comprises a number of incorrect messages within an ignition cycle.

8. A method according to claim 1, wherein the remedial action comprises disabling closed loop electronic stability control (ESC) during open loop variable gear ratio (VGR) control.

9. A method according to claim 1, wherein the remedial action comprises locking an AFS actuator during open loop variable gear ratio (VGR) control.

10. A method according to claim 1, wherein the remedial action comprises gracefully exiting during closed loop electronic stability control (ESC).

11. A method according to claim 1, wherein the remedial action comprises locking an AFS actuator during closed loop electronic stability control (ESC).

12. A method according to claim 1, wherein the invalid parameter represents one of:

a hand wheel angle, a hand wheel angle rate, a driver intended road wheel angle, an actual front road wheel angle, an actual actuator angle, an actual front angle delivered, a variable gear ratio (VGR) override command, an actuator lock status, a HWS/VGR/stabilitrak failure status, a vehicle reference velocity, or an AFS front angle modifier command.

13. A method for parametric active front steer (AFS) remedial action for a vehicle, the method comprising:

obtaining an incorrect message count;

detecting an error if the incorrect message count is greater than or equal to a predetermined measure;

determining an invalid parameter upon detecting the error; and

setting default values of valid parameters corresponding to the invalid parameter.

14. A method according to claim 13, wherein the determining step comprises determining the invalid parameter corresponding to a parameter received via a correct message prior to detecting the error.

15. An active front steer (AFS) system for a vehicle, the system comprising:

an AFS module;

a supervisory control module (SCM) coupled to the AFS module;

a hand wheel sensor (HWS) module coupled to the AFS module and to the SCM, the HWS module being configured to send HWS parameters to the SCM and to the AFS module, wherein the AFS module is configured to send AFS module parameters to the SCM and to receive SCM parameters from the SCM; and

a processing logic element coupled to the AFS module, and configured to;

monitor AFS system messages for error occurrences;

detect an error corresponding to an invalid parameter;

select a remedial action corresponding to the invalid parameter; and

take the remedial action by setting valid parameters corresponding to the invalid parameter.

16. A system according to claim 15, wherein the processing logic element is further configured to:

obtain an incorrect message count;

detect the error if the incorrect message count is greater than or equal to a predetermined measure;

determine the invalid parameter based upon the error; and

set default values of valid parameters corresponding to the invalid parameter.

17. A system according to claim 15, wherein the processing logic element is further configured to obtain the invalid parameter from a correct message received prior to detecting the error.

18. A system according to claim 15, further comprising a variable gear ratio control (VGR) module coupled to the processing logic element.

19. A system according to claim 15, further comprising a memory module coupled to the processing logic element and configured to store tables of valid parameters corresponding to each invalid parameter.