Long-Duration Offset Compensation of a Sensor

• US 20070208524A1
• Filed: 02/17/2005
• Published: 09/06/2007
• Est. Priority Date: 04/15/2004
• Status: Abandoned Application

• Current Assignee: Continental AG
• Original Assignee: Continental Teves AG & Co. OHG (Continental AG)
• Inventors: Herbst, Ralf, Niepelt, Mathias, Zieschang, Rene
• Application Number:
  US11/578,563
• Publication Number:
  US 20070208524A1
• Time in Patent Office: Days
• US Class Current: 702/85
• CPC Class Codes: B60T 2250/06 Sensor zero-point adjustment; Offset compensation
• CPC Class Codes: G01P 21/00 Testing or calibrating of apparatus or devices covered by the preceding groups

Abstract

A method serves to compensate the offset of a sensor signal, in particular of an acceleration sensor detecting movements in the driving direction of a vehicle (longitudinal acceleration sensor). The offset of the signal during the lifetime of the vehicle adapted by means of a long-duration offset filter (LZOF). More particularly, the measuring signal for determining the offset, preferably, is not filtered in response to time but in response to travel.

Claims

1-24. -24. (canceled)

25. A method for the offset compensation of an electric signal of a sensor by determining a compensation value S_Off, comprising the step of adjusting the compensation value S_Off on a long-term basis over the course of the lifetime of the sensor.

26. The method as claimed in claim 25,

wherein the compensation value S_Off is adjusted depending on a distance covered by the vehicle.

27. The method as claimed in claim 26,

comprising the steps of

taking into account distance intervals for fixing intermediate calculation moments, and

triggering a current intermediate calculation for the calculation of the compensation value at the intermediate calculation moments.

28. The method as claimed in claim 25,

comprising the step of determining a sequence of compensation correction values, wherein the compensation value S_Off is only determined when a sufficient number of compensation correction values have been determined.

29. The method as claimed in claim 28,

comprising the step of weighting at least the compensation values S_Off or the compensation correction values corresponding to the distances covered, at which the respective values prevailed.

30. The method as claimed in claim 25,

comprising the step of compensating the offset, wherein the offset compensation is only performed when a sufficient number of compensation values S_Off have been determined.

31. The method as claimed in claim 25,

wherein top and bottom limit values are fixed for the compensation value S_Off, which the compensation value S_Off is not allowed to exceed.

32. The method as claimed in claim 31,

wherein the top and bottom limit values have the same absolute value but opposite signs.

33. The method as claimed in claim 25,

wherein for the offset compensation, apart from the raw signal of the sensor, also a reference signal S_Ref of another sensor is used, which represents a measured variable of the sensor or a quantity from which the measured variable can be derived, the method comprising the step of producing a difference S_Dif of an offset-compensated useful signal S_use and the reference signal S_Ref is produced.

34. The method as claimed in claim 33,

comprising the step of producing an integral or a sum S_Sum with respect to the difference S_Dif within the limits of a determined time or distance range, based on which the correction of the sensor offset is determined.

35. The method as claimed in claim 34,

wherein a counter Z_Sum is incremented per integration step or per summation step, and the number of steps is thus counted.

36. The method as claimed in claim 35,

wherein the compensation correction value is determined according to the formula S_Delta=S_Sum/Z_Sum.

37. The method as claimed in claim 36,

wherein a distance covered is determined from the counter Z_Sum.

38. The method as claimed in at least one of claim 34,

wherein a height profile of the travel is determined from the value S_Sum.

40. The method as claimed in claim 34,

wherein a predetermined value for the distance range is defined, and in the case that a covered distance is smaller than the predetermined value, already determined intermediate values are stored in a non-volatile memory.

41. The method as claimed in claim 25,

comprising the step of determining acceleration and deceleration phases by way of an inquiry during the compensation, and omitting the compensation during such a phase.

42. The method as claimed in claim 25,

comprising the step of checking for an erroneous input signal.

43. The method as claimed in claim 25,

comprising the step of checking for an unusual driving situation.

44. The method as claimed in claim 43,

wherein it is checked, whether at least one of the control functions is active. which are members of the group consisting of anti-lock system, traction control system, electronic stability program, electronic brake assist system, and hydraulic brake assist system.

45. The method as claimed claim 25,

wherein an error counter is used.

46. The method as claimed in claim 45,

comprising the step of increasing the error counter in the event of an erroneous input signal and in the event of an unusual driving situation.

39. The method as claimed in 34,

wherein a predetermined value for the distance range is defined, and in the case that a covered distance is smaller than the predetermined value, correction of the compensation value S_Off is allowed irrespective of the distance covered.