Systems and Methods for 3-Axis Accelerometer Calibration

• US 20130073142A1
• Filed: 09/19/2012
• Published: 03/21/2013
• Est. Priority Date: 09/20/2011
• Status: Active Grant

• Current Assignee: CalAmp Corporation
• Original Assignee: CalAmp Corporation
• Inventors: Hergesheimer, Peter, Sprague, Todd, Dlagnekov, Alexandre
• Granted Patent: US 9,217,757 B2
• Time in Patent Office: Days
• US Class Current: 701/33.1
• 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

Systems and methods for calibrating the alignment of 3-axis accelerometers in accordance embodiments of the invention are disclosed. In one embodiment of the invention, a telematics system includes a global positioning system (GPS) receiver. an accelerometer, and a processor, wherein the GPS receiver is configured to determine velocity information, wherein the accelerometer is configured to determine accelerometer acceleration information along one or more accelerometer axes, and wherein the processor is configured to receive a velocity information sample using the GPS receiver, determine GPS acceleration information along one or more vehicle axes using the velocity information sample, receive accelerometer acceleration information samples using the accelerometer, and calibrate one of the vehicle axes to an accelerometer axis in the one or more accelerometer axes using the GPS acceleration information sample and the accelerometer acceleration information sample.

Claims

1. A telematics system, comprising:

a global positioning system (GPS) receiver;

an accelerometer; and

a processor;

wherein the GPS receiver is configured to determine velocity information;

wherein the accelerometer is configured to determine accelerometer acceleration information along one or more accelerometer axes; and

wherein the processor is configured to;

receive a velocity information sample using the GPS receiver;

determine GPS acceleration information along one or more vehicle axes using the velocity information sample;

receive accelerometer acceleration information samples using the accelerometer; and

calibrate one of the vehicle axes to an accelerometer axis in the one or more accelerometer axes using the GPS acceleration information sample and the accelerometer acceleration information sample.

2. The telematics system of claim 1, wherein the accelerometer is a 3-axis accelerometer.

3. The telematics system of claim 1, wherein:

the accelerometer comprises a first sampling rate; and

the telematics system further comprises an accelerometer accumulator configured to accumulate a plurality of accelerometer acceleration information samples taken at the first sampling rate.

4. The telematics system of claim 3, wherein:

the GPS receiver comprises a second sampling rate; and

the telematics system further comprises a GPS accumulator configured to accumulate a plurality of velocity information samples taken at the second sampling rate.

5. The telematics system of claim 4, wherein the processor is configured to match the first sampling rate to the second sampling rate.

6. The telematics system of claim 1, wherein the processor is configured to calibrate a vehicle axis to an accelerometer axis using a least squares method.

7. The telematics system of claim 6, wherein the processor is configured to perform the least squares method using a Gaussian elimination solver.

8. The telematics system of claim 7, further comprising motion sample storage configured to store a plurality of motion samples, where motion samples are selected from the group consisting of GPS location information samples and accelerometer acceleration information samples.

9. The telematics system of claim 8, wherein the processor is configured to perform the least squares method using at least one motion sample in the plurality of motion samples.

10. The telematics system of claim 1, wherein the processor is further configured to:

detect a vertical vector in the calibrated vehicle axes; and

recalibrate the calibrated vehicles axes using the using the GPS acceleration information sample, the accelerometer acceleration information sample, and the detected vertical vector.

11. The telematics system of claim 1, wherein the processor is further configured to:

detect a lateral vector in the calibrated vehicle axes; and

recalibrate the calibrated vehicles axes using the using the GPS acceleration information sample, the accelerometer acceleration information sample, and the detected lateral vector.

12. A method for calibrating an accelerometer, comprising:

receiving velocity information samples using a telematics system, where the telematics system is mounted in a vehicle having one or more vehicle axes;

determining vehicle acceleration information samples along a vehicle axis in the one or more vehicle axes using the velocity information and the telematics system;

receiving accelerometer acceleration information samples along one or more accelerometer axes using the telematics system; and

calibrating a vehicle axis in the one or more vehicle axes to an accelerometer axis in the one or more accelerometer axes using the vehicle acceleration information samples, the accelerometer acceleration information samples, and the telematics system.

13. The method of claim 12, wherein receiving velocity information samples using the telematics system further includes receiving the velocity information samples at a first sampling rate.

14. The method of claim 13, wherein receiving accelerometer acceleration information samples at a second sampling rate.

15. The method of claim 14, further comprising matching the first sampling rate to the second sampling rate using the telematics system.

16. The method of claim 12, wherein calibrating a vehicle axis to an accelerometer axis includes performing a least squares method using the telematics system.

17. The method of claim 16, wherein performing the least squares method includes performing a Gaussian elimination solver using the telematics system.

18. The method of claim 17, further comprising storing a plurality of motion samples using the telematics system, where motion samples are selected from the group consisting of velocity information samples and accelerometer acceleration information samples.

19. The method of claim 17, further comprising performing the least squares method using at least one motion sample in the plurality of motion samples and the telematics system.

20. The method of claim 12, further comprising:

detecting a vertical vector in the calibrated vehicle axes using the telematics system; and

recalibrating the calibrated vehicles axes using the using the GPS acceleration information sample, the accelerometer acceleration information sample, the detected vertical vector, and the telematics system.

21. The method of claim 12, further comprising:

detecting a lateral vector in the calibrated vehicle axes using the telematics system; and

recalibrating the calibrated vehicles axes using the using the GPS acceleration information sample, the accelerometer acceleration information sample, the detected lateral vector, and the telematics system.