Impact sensor calibration tool

• US 8,762,009 B2
• Filed: 11/18/2010
• Issued: 06/24/2014
• Est. Priority Date: 11/18/2010
• Status: Active Grant

• Current Assignee: Id Systems Incorporated (PowerFleet, Inc.)
• Original Assignee: Id Systems Incorporated (PowerFleet, Inc.)
• Inventors: Ehrman, Kenneth S., Ehrman, Michael L., Smail, Scott, Charitonos, Michael
• Primary Examiner(s): Holwerda, Stephen
• Application Number:
  US12/949,191
• Publication Number:
  US 20120130586A1
• Time in Patent Office: 1,314 Days
• Field of Search: 280/734, 280/735, 340/436, 340/438, 701/45, 701/46, 701/47, 180/282, 180/283, 180/284, 180/285
• US Class Current: 701/47
• CPC Class Codes: B60R 21/01 Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents electrical circuits for transmission of signals between steering wheel and the vehicle itself B60R16/027; for electrically actuating belt retractor locking means B60R22/343

Abstract

An impact sensor calibration tool, wherein an impact sensor is installed on a vehicle and in wireless communication with a processor, which analyzes data reported by the impact sensor. Specifically, the impact sensor of the present invention continuously measures two dimensional acceleration of a vehicle. Changes in vehicle acceleration create impulse data and the impact sensor reports this data to a processor. The processor performs statistical calculations on the data to identify the vehicle'"'"'s normal use operation and from this, develops an impact threshold wherein impulses exceeding this threshold are identified as impacts. The impacts may be further characterized as real impacts and stored in memory for subsequent analysis.

Claims

1. A computer-implemented method of determining vehicle impact events, comprising:

continuously acquiring, via an impact sensor, vehicle acceleration data;

continuously receiving, at a computing device, vehicle acceleration data acquired by the impact sensor;

performing, via the computing device, statistical calculations on the continuously received vehicle acceleration data, wherein the statistical calculations comprise;

calculating a recursive average of the acceleration data; and

calculating a recursive standard deviation of the acceleration data,

wherein the calculated recursive average and recursive standard deviation identify a normal use operation;

setting, via the computing device, an impact threshold based on the calculated normal use operation;

determining, via the impact sensor, vehicle impulses based on changes in the acquired vehicle acceleration data;

identifying, via the computing device, received vehicle impulses that exceed the impact threshold, wherein vehicle impulses exceeding the impact threshold are identified as impacts;

responsive to identifying impacts, characterizing, via the computing device, each impact as a normal use impact or a real impact;

responsive to characterizing an impact as a real impact, recording, via the computing device, the real impact for subsequent analysis;

wherein vehicle impulses less than or substantially equal to a sum of the recursive average and the recursive standard deviation are normal use impacts; and

wherein vehicle impulses greater than a sum of the recursive average and the recursive standard deviation are real impacts.

2. The method of claim 1, wherein the impact threshold is continuously set based on current vehicle acceleration data and historical vehicle acceleration data.

3. The method of claim 1, wherein sensing vehicle acceleration data comprises sensing two-dimensional vehicle acceleration data.

4. The method of claim 1, wherein calculating the recursive standard deviation comprises utilizing a function that approximates standard deviation, wherein the function returns an integer approximation.

5. The method of claim 1, wherein characterizing each impact as a normal use impact or a real impact comprises:

identifying a duration of time a vehicle impulse lasts; and

comparing the duration of the vehicle impulse to a duration of a threshold impulse, wherein the difference between the duration of the vehicle impulse and the duration of the threshold impulse represents a sustain sample.

6. The method of claim 1, further comprising calculating an impulse energy level of a real impact.

7. The method of claim 6, wherein calculating the impulse energy level of a real impact comprises:

identifying a maximum impulse of the real impact and translating the maximum impulse into a corresponding first point in a quadrant of a Cartesian coordinate plane, wherein the quadrant of the Cartesian plane comprises an origin;

identifying a duration of the impulse of the real impact and translating the duration of the impulse into a corresponding second point in the quadrant of the Cartesian coordinate plane;

identifying a sustain of the impulse of the real impact and translating the sustain of the impulse into a corresponding third point in the quadrant of the Cartesian coordinate plane; and

calculating the area of the quadrilateral formed using the first point, the second point, the third point, and the origin of the Cartesian plane.

8. The method of claim 1, further comprising:

tracking a vehicle using a global positioning system, wherein the global positioning system is adapted to assist with setting the impact threshold.

9. The method of claim 1, further comprising:

uploading the impacts with a confidence level, wherein the confidence level provides an indication of how effectively the statistical calculations are working.

10. The method of claim 1, further comprising categorizing the impacts by impact direction.

11. A computer-implemented method of determining vehicle impact events, comprising:

continuously acquiring, via an impact sensor, vehicle acceleration data;

continuously receiving, at a computing device, vehicle acceleration data acquired by the impact sensor;

performing, via the computing device, statistical calculations on the continuously received vehicle acceleration data, wherein the statistical calculations comprise;

calculating a recursive average of the acceleration data; and

calculating a factored recursive standard deviation of the acceleration data,

wherein the calculated recursive average and factored recursive standard deviation identify a normal use operation;

setting, via the computing device, an impact threshold based on the calculated normal use operation;

determining, via the impact sensor, vehicle impulses based on changes in the acquired vehicle acceleration data;

identifying, via the computing device, received vehicle impulses that exceed the impact threshold, wherein vehicle impulses exceeding the impact threshold are identified as impacts;

responsive to identifying impacts, characterizing, via the computing device, each impact as a normal use impact or a real impact;

responsive to characterizing an impact as a real impact, calculating, via the computing device, an impulse energy level of the real impact;

further responsive to characterizing an impact as a real impact, recording, via the computing device, the real impact for subsequent analysis;

wherein vehicle impulses less than or substantially equal to a sum of the recursive average and the factored recursive standard deviation are normal use impacts; and

wherein vehicle impulses greater than a sum of the recursive average and the factored recursive standard deviation are real impacts.

17. The method of claim 11, wherein the recursive average and the factored recursive standard deviation are calculated separately on the x-axis, the y-axis, and the z-axis.

18. The method of claim 11, wherein the factored recursive standard is calculated for a single vehicle.

19. The method of claim 11, wherein the factored recursive standard is calculated for a plurality of vehicles.

12. A non-transitory computer readable medium having program instructions tangibly stored thereon executable by a processor to perform a method for continuously sensing vehicle impact events, comprising:

continuously receiving vehicle acceleration data from an impact sensor, wherein the impact sensor acquires vehicle acceleration data based on changes in vehicle acceleration;

performing statistical calculations on the continuously received vehicle acceleration data, wherein the statistical calculations comprise;

calculating a recursive average of the acceleration data; and

calculating a recursive standard deviation of the acceleration data,

wherein the calculated recursive average and recursive standard deviation identify a normal use operation;

setting an impact threshold based on the calculated normal use operation;

receiving vehicle impulses from the impact sensor, wherein the impact sensor determines vehicle impulses based on changes in the acquired vehicle acceleration data;

identifying received vehicle impulses that exceed the impact threshold, wherein vehicle impulses exceeding the impact threshold are identified as impacts;

responsive to identifying impacts, characterizing each impact as normal use impact or real impact;

responsive to characterizing an impact as a real impact, recording the real impact for subsequent analysis;

wherein vehicle impulses less than or substantially equal to a sum of the recursive average and the recursive standard deviation are normal use impacts; and

wherein vehicle impulses greater than a sum of the recursive average and the recursive standard deviation are real impacts.

13. The computer readable medium of claim 12, wherein the impact threshold is continuously set based on current vehicle acceleration data and historical vehicle acceleration data.

14. The computer readable medium of claim 12, wherein calculating the recursive standard deviation comprises utilizing a function that approximates standard deviation, wherein the function returns an integer approximation.

15. The computer readable medium of claim 12, wherein characterizing each impact as normal use impact or a real impact comprises:

identifying a duration of time a vehicle impulse lasts; and

comparing the duration of the vehicle impulse to a duration of a threshold impulse, wherein the difference between the duration of the vehicle impulse and the duration of the threshold impulse represents a sustain sample.

16. The method of claim 12, further comprising calculating an impulse energy level of a real impact.