Method for correction of inertial sensor mounting offsets

• US 7,707,867 B2
• Filed: 02/28/2007
• Issued: 05/04/2010
• Est. Priority Date: 08/31/2004
• Status: Active Grant

• Current Assignee: Kelsey-Hayes Co. (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: Kelsey-Hayes Co. (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Babala, Mike, Fontenot, Kevin
• Primary Examiner(s): Williams; Hezron
• Assistant Examiner(s): FAYYAZ, NASHMIYA SAQIB
• Application Number:
  US11/712,321
• Publication Number:
  US 20070150221A1
• Time in Patent Office: 1,161 Days
• Field of Search: 73 137- 138
• US Class Current: 73/1.38
• CPC Class Codes: B60T 2250/06 Sensor zero-point adjustment; Offset compensation
• CPC Class Codes: B60T 2250/062 loosing zero-point calibration of yaw rate sensors when travelling on banked roads or in case of temperature variations
• CPC Class Codes: B60T 8/368 combined with other mechanical components, e.g. pump units, master cylinders
• CPC Class Codes: G01C 21/188 for accumulated errors, e.g. by coupling inertial systems with absolute positioning systems
• CPC Class Codes: G01C 25/005 initial alignment, calibration or starting-up of inertial devices
• CPC Class Codes: G01P 1/00 Details of instruments
• CPC Class Codes: G01P 15/18 in two or more dimensions
• CPC Class Codes: G01P 21/00 Testing or calibrating of apparatus or devices covered by the preceding groups

Abstract

A method for calibration of motion sensors included in a vehicle electronic brake control system includes measuring sensor offset errors at different points in the assembly of the system and the vehicle and then combining the offset errors to obtain net offset errors for use with an electronic brake system.

Claims

1. A method for mitigating cross-axis mounting error for an inertial sensor comprising the steps of:

(a) mounting an inertial sensor within an electronic control unit for an electronic stability control system that is attached to a hydraulic control valve, the electronic control unit including a non-volatile memory, with the combination of the electronic control unit and hydraulic control valve attached to a mounting bracket to form a controller assembly;

(b) mounting the controller assembly upon a rotatable test stand;

(c) rotating the test stand and controller assembly into a position;

(d) determining a combined assembly mounting offset error due to combined errors from mounting of the sensor within the electronic control unit and mounting of the combination of the electronic control unit and the hydraulic control valve upon the bracket;

(e) storing the combined assembly mounting offset error within the electronic control unit non-volatile memory;

(f) installing the controller assembly upon a vehicle;

(g) positioning the vehicle on a horizontal surface;

(h) measuring an installation offset error while the vehicle is stationary;

(i) determining a corrected installation offset error by combining the combined assembly mounting offset error measured in step (d) with the installation offset error measured in step (h); and

(j) storing the corrected installation offset error in the electronic control unit non-volatile memory.

2. The method according to claim 1 wherein the test stand and controller assembly are rotated into a first position in step (c) and further wherein determination of the combined assembly mounting offset error in step (d) includes the following substeps:

(d1) taking a first sensor reading;

(d2) rotating the test stand and controller assembly into a second position;

(d3) taking a second sensor reading; and

(d4) combining the first and second sensor readings to determine an assembly offset error.

3. The method according to claim 2 wherein the inertial sensor is intended to sense motion relative one of three orthogonal axes with the remaining two orthogonal axes being non-sensing orthogonal axes for the sensor and with the first position of the test stand and controller assembly in step (c) aligned with a selected one of the non-sensing orthogonal axes and with the combined assembly offset error determined in step (d4) corresponding to the selected orthogonal axis and further wherein steps (c) through (e) are repeated for the remaining non-sensing orthogonal axis with the resulting combined assembly offset errors being combined in step (i) with the corresponding installation offset errors measured in step (h).

4. The method according to claim 2 wherein the test stand and controller assembly is rotated about at least one axis.

5. The method according to claim 3 wherein the sensor includes a sensor non-volatile memory and, prior to step (a), the inertial sensor is placed upon a true surface and sensor offset errors are measured for the inertial sensor relative to the true surface with the sensor offset errors being stored in the sensor non-volatile memory, the sensor offset errors being combined with the combined assembly mounting offset errors determined in step (d) and the combined assembly mounting offset errors being stored in the electronic control unit non-volatile memory in step (e).

6. The method according to claim 5 wherein the test stand and controller assembly is rotated through 180 degrees in step (d2).

7. The method according to claim 4 wherein the test stand and controller assembly is sequentially rotated about a plurality of orthogonal axes.

8. The method according to claim 6 wherein the electronic control unit is a Vehicle Stability Control system Electronic Control Unit.

9. The method according to claim 8 wherein the inertial sensor is mounted within the Vehicle Stability Control system Electronic Control Unit.

10. The method according to claim 9 wherein the inertial sensor is mounted directly upon a printed circuit board that is disposed within the Vehicle Stability Control system Electronic Control Unit.

11. The method according to claim 10 wherein a plurality of inertial sensors are mounted in the Vehicle Stability Control system Electronic Control Unit and the method is applied to determine corrected offset errors for each of the sensors.

12. The method according to claim 11 wherein the plurality of inertial sensors includes at least one accelerometer.

13. The method according to claim 12 wherein the combined offset error for at least one of the inertial sensors is utilized to determine a threshold value for disabling the Vehicle Stability Control system.

14. The method according to claim 12 wherein the electronic control unit is electrically connected to at least one other vehicle control system and further wherein the corrected installation offset errors are transmitted to the other vehicle control system for use therein.

15. The method according to claim 11 wherein the plurality of inertial sensors includes at least one yaw sensor.

16. The method according to claim 6 wherein the electronic control unit non-volatile memory stores an algorithm for carrying out the determination of the corrected installation offset errors in step (i).