Two-point calibration of a longitudinal acceleration sensor

• US 6,347,541 B1
• Filed: 06/29/1999
• Issued: 02/19/2002
• Est. Priority Date: 06/29/1998
• Status: Expired due to Fees

• Current Assignee: Continental Teves Incorporated (Continental AG)
• Original Assignee: Continental Teves Incorporated (Continental AG)
• Inventors: Maleki, Ali F.
• Primary Examiner(s): NOLAND, THOMAS
• Application Number:
  US09/342,764
• Time in Patent Office: 966 Days
• Field of Search: 73/13.8, 73/13.7, 702/87, 702/104, 702/96, 702/141
• US Class Current: 73/1.38
• 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 of calibrating an acceleration sensor by utilizing a two point analysis involves positioning the acceleration sensor at a first angle, measuring a first output voltage and positioning the sensor at a second angle and measuring a second output voltage and thereafter calculating a sensitivity ratio and a zero position output voltage based on the angles and voltages. Further, the method of the present invention optionally includes a second calibration after the acceleration sensor is installed onto a vehicle. Thus, the present invention improves accuracy in determining actual vehicle acceleration.

Claims

1. A method of calibrating an acceleration sensor for a vehicle, the acceleration sensor being connected to an electronic control unit, comprising the steps of:

positioning the acceleration sensor at a first angle A1;

communicating the first angle A1 to the electronic control unit;

measuring a first output voltage V1 of the acceleration sensor at the first angle A1;

positioning the acceleration sensor at a second angle A2;

communicating the second angle A2 to the electronic control unit;

measuring a second output voltage V2 of the acceleration sensor at the second angle A2;

calculating a sensitivity factor as a ratio equal to a difference between the first and second output voltages V2−

V1 divided by a difference between the first and second angles A2−

A1;

calculating a zero position output voltage which is equal to the first output voltage minus a product of the sensitivity factor times the sine of the first angle.

2. The method of claim 1, wherein the first angle is approximately 90 degrees and the second angle is approximately −

90 degrees.

3. The method of claim 1, wherein the first angle is approximately 0 degrees and the second angle is approximately 90 degrees.

4. The method of claim 1, further comprising:

installing the acceleration sensor onto the vehicle and then further calibrating the sensor comprising the steps of;

placing the vehicle at a predetermined third angle A3;

communicating the third angle A3 to the electronic control unit

measuring a third output voltage of the acceleration sensor at the third angle A3;

calculating a second sensitivity factor as a ratio equal to a difference between the third output voltage and one of the first and second output voltages V3−

V2/1 divided by a difference between the third angle and one of the first and second angles A3−

A2/1;

calculating a second zero position output voltage which is equal to the third output voltage minus a product of the sensitivity factor times the sine of the third angle.

5. The method of claim 4, wherein the first, second and third angles are pitch angles.

6. The method of claim 4, wherein the first, second and third angles are yaw angles.

7. A method of calibrating an acceleration sensor for a vehicle having a silicon proof mass resiliently suspended between a pair of capacitor plates and connected to an electronic control unit comprising:

positioning the acceleration sensor at a first angle A1;

communicating and storing the first angle A1 with the electronic control unit;

measuring and storing a first output voltage V1 of the acceleration sensor at the first angle A1;

positioning the acceleration sensor at a second angle A2;

communicating and storing the second angle A2 with the electronic control unit;

measuring and storing a second output voltage V2 of the acceleration sensor at the second angle A2;

calculating and storing a sensitivity factor as a ratio equal to a difference between the first and second output voltages V2−

V1 divided by a difference between the first and second angles A2−

A1;

calculating and storing a zero position output voltage which is equal to the first output voltage minus a product of the sensitivity factor times the sine of the first angle.