METHOD AND APPARATUS FOR DETERMINING A VALUE OF A ZERO POINT OFFSET OF A YAW RATE SENSOR

• US 20110035097A1
• Filed: 03/31/2008
• Published: 02/10/2011
• Est. Priority Date: 03/30/2007
• Status: Active Grant

• Current Assignee: Penny and Giles Controls Limited (Curtiss-Wright Corporation)
• Original Assignee: Penny and Giles Controls Limited (Curtiss-Wright Corporation)
• Inventors: Lewis, Jason
• Granted Patent: US 8,649,936 B2
• Time in Patent Office: Days
• US Class Current: 701/36
• CPC Class Codes: A61G 5/045 Rear wheel drive
• CPC Class Codes: B60L 3/0038 relating to sensors
• CPC Class Codes: G01C 19/42 for indicating rate of turn; for integrating rate of turn
• CPC Class Codes: G01C 25/00 Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass testing, calibrating or compensating compasses G01C17/38

Abstract

There is described a method for determining a value of a zero point offset of a yaw rate sensor. The method comprises measuring over time the output of the yaw rate sensor, determining whether the measured output has remained within a set of limits for a pre-determined period and if it is determined that the measured output has remained within the limits for the pre-determined period, using at least one measured value of the output to determine the value of the zero point offset.

Claims

1. A method for determining a value of a zero point offset of a yaw rate sensor, the method comprising:

measuring over time the output of the yaw rate sensor, determining whether the measured output has remained within a set of limits for a pre-determined period and if it is determined that the measured output has remained within the limits for the pre-determined period, using at least one measured value of the output to determine the value of the zero point offset.

2. A method according to claim 1, wherein the set of limits is determined in dependence upon at least one measured value of the output of the yaw rate sensor.

3. A method according to claim 2, wherein the set of limits comprises an upper limit and a lower limit, the upper limit being set a pre-determined amount higher than a value determined in dependence upon the at least one measured value and the lower limit being set at a pre-determined amount lower than the value determined in dependence upon the at least one measured value.

4. A method according to claim 2, wherein the set of limits comprises an upper limit and a lower limit, the upper limit being set a pre-determined amount higher than the at least one measured value and the lower limit being set at a pre-determined amount lower than the at least one measured value.

5. A method according to claim 1, wherein the set of limits comprises an upper limit and a lower limit the values of which can vary over the predetermined period in dependence upon variations in the measured output.

6. A method according to claim 5, wherein the values of the upper and lower limits can vary over the pre-determined period in dependence upon a monitored average value of the measured output.

7. A method according to claim 6, wherein values of the upper and lower limits are respectively maintained a pre-determined amount above and below the monitored average value of the measured output.

8. A method according to claim 1, wherein the step of determining whether the measured output has remained within the set of limits for the pre-determined period comprises obtaining a sequence of values of the measured output and for each value in the sequence, determining whether it is within the limits, prior to the next value in the sequence being obtained.

9. A method according to claim 5, wherein the step of determining whether the measured output has remained within the set of limits for the pre-determined period comprises obtaining a sequence of values of the measured output and for each value in the sequence, determining whether current maximum and minimum values of the sequence are within current determined values of the limits, prior to the next value in the sequence being obtained.

10. A method according to claim 1, wherein the set of limits has predetermined upper and lower values that are independent of the measured output.

11. A method according to claim 10 wherein the pre-determined upper and lower values of the set of limits are recommended permissible upper and lower values for the zero point offset of the sensor.

12. A method according to claim 1, wherein the method is ended and then started afresh if it is determined that the measured output is outside the set of limits.

13. A method according to claim 1, the method further comprising, using a timer or counter to determine whether the pre-determined period has been reached.

14. A method according to claim 1, wherein the step of using at least one measured value of the output to determine the value of the zero point offset comprises, calculating an average value of a plurality of measured values of the output and using the average value as the value of the zero point offset.

15. A method according to claim 1, the method comprising determining whether the measured output has remained within a first set of limits and a second set of limits for the pre-determined period and if it is determined that the measured output has remained within the first set of limits and the second set of limits for the pre-determined period, using at least one measured value of the output to determine the value of the zero point offset.

16. A method according to claim 15, wherein the first set of limits is determined in dependence upon at least one measured value of the output of the yaw rate sensor.

17. A method according to claim 16, wherein the first set of limits comprises an upper limit and a lower limit, the upper limit being set a predetermined amount higher than a value determined in dependence upon the at least one measured value and the lower limit being set at a pre-determined amount lower than the value determined in dependence upon the at least one measured value.

18. A method according to claim 17, wherein the first set of limits comprises an upper limit and a lower limit, the upper limit being set a predetermined amount higher than the at least one measured value and the lower limit being set at a pre-determined amount lower than the at least one measured value.

19. A method according to claim 18, wherein the first set of limits comprises an upper limit and a lower limit the values of which vary over the pre-determined period in dependence upon variations in the measured output.

20. A method according to claim 19, wherein the values of the upper and lower limits of the first set of limits vary over the pre-determined period in dependence upon a monitored average value of the measured output.

21. A method according to claim 20, wherein values of the upper and lower limits of the first set of limits are respectively maintained a pre-determined amount above and below the monitored average value of the measured output.

22. A method according to claim 15, wherein the step of determining whether the measured output has remained within the first set of limits for the pre-determined period comprises obtaining a sequence of values of the measured output and for each value in the sequence, determining whether it is within the limits, prior to the next value in the sequence being obtained.

23. A method according to claim 19 wherein the step of determining whether the measured output has remained within the first set of limits for the pre-determined period comprises obtaining a sequence of values of the measured output and for each value in the sequence, determining whether current maximum and minimum values of the sequence are within current determined values of the limits, prior to the next value in the sequence being obtained.

24. A method according to claim 15, wherein the second set of limits have pre-determined upper and lower values that are independent of the measured output.

25. A method according to claim 24 wherein the pre-determined upper and lower values of the second set of limits are recommended permissible upper and lower values for the zero point offset of the sensor.

26. A method according to claim 15, wherein the method is ended and then started afresh if it is determined that the measured output is outside the first set of limits or the second set of limits.

27. A method according to claim 1, wherein the method is implemented by a vehicle control system which system prevents the vehicle from being drivable until the value of the zero point offset is determined.

28. Apparatus comprising an arrangement for implementing the method of claim 1.

29. A method of operating a vehicle comprising a control system comprising a yaw rate sensor, in which method the control system measures the output of the yaw rate sensor when the vehicle is at rest, tests the measured output in accordance with test criteria to determine if the measured output is reliable, and in response to determining that the measured output is reliable uses the measured output to determine a value for a zero point offset of the yaw and inhibits the vehicle from being operational until after it has determined the value for the zero point offset.

30. A method according to claim 29, in which method the control system enables the vehicle to be operational after the value for the zero point offset has been determined.

31. A vehicle control system arranged to implement the method of claim 29.

32. A vehicle comprising a vehicle control system according to claim 31.

33. A vehicle according to claim 32, wherein the vehicle is an electric vehicle.