VARIABLE STEP TRACKING

• US 20120239333A1
• Filed: 09/19/2011
• Published: 09/20/2012
• Est. Priority Date: 09/17/2010
• Status: Active Grant

• Current Assignee: Edward K. Welch II
• Original Assignee: Seer Technology, Inc.
• Inventors: Keene, Richard M., Garland, Stephen Kent, Crouch, Milne T., Maxwell, Daniel Travis, Maxwell, Daniel C.
• Granted Patent: US 9,170,124 B2
• Time in Patent Office: Days
• US Class Current: 702/94
• CPC Class Codes: G01C 22/006 Pedometers

Abstract

Variable step tracking is described in which a monitoring station is operable to receive data signals representative of step movement of an asset as detected by a monitoring device carried by the asset. A database stores a step length of the asset. A step length modification module modifies the step length based on at least one of energy, asset orientation, direction, and frequency associated with the step movement. An asset position is estimated with respect to a known location based on cumulative step lengths.

Claims

1. A variable step tracking device, comprising:

a monitoring station operable to receive data signals representative of step movement of an asset as detected by a monitoring device carried by the asset;

a database for storing a step length of the asset;

a step length modification module for modifying the step length based on at least one of energy, asset orientation, direction, and frequency associated with the step movement; and

a processor for estimating an asset position with respect to a known location based on cumulative step lengths.

2. The device of claim 1, further comprising a non-transitory computer readable storage medium having computer readable instructions embodied therein which, when executed by the processor, identify a step taken by the asset or identify the at least one of energy, asset orientation, direction, and frequency associated with the step using a wavelet.

3. The device of claim 2, wherein the wavelet comprises a first amplitude, a second amplitude, and a third amplitude, the second amplitude being a negative amplitude less than the first amplitude and the third amplitude being a greater amplitude than the first amplitude, the wavelet comprising a first declined portion declining from the first amplitude to the second amplitude, a inclined portion inclining from the second amplitude to the third amplitude, and a second declined portion declining from the third amplitude toward the first amplitude.

4. The device of claim 3, wherein the first and second declined portions and the inclined portion respectively comprise straight, linear segments.

5. The device of claim 3, wherein the first and second declined portions and the inclined portion comprise non-linear segments.

6. The device of claim 3, wherein the processor is configured to smooth peaks of the wavelet to assist in detection discrimination of a change in a direction of motion caused by a step movement of the asset.

7. The device of claim 1, wherein if the at least one movement detection device resets and is temporarily unable to detect movement, the processor estimates an asset position with respect to a known location based on an average trajectory.

8. The device of claim 1, wherein the database further stores an energy level associated with the step movement of the asset, wherein an average energy level is derived from a brisk walk energy level that is representative of at least one type of movement comprising at least one of walking, running, and crawling of the asset.

9. The device of claim 8, wherein the at least one movement detection device detects the energy level associated with the step movement of the asset and the processor estimates an asset position based on the at least one type of movement.

10. The device of claim 1, wherein the movement detection device is comprised of at least one accelerometer, gyroscope, barometer, altimeter, and/or magnetometer.

11. A method for variable step tracking, comprising:

measuring a step length of an asset;

positioning the asset at a known location;

detecting step movement of the asset using a movement detection device;

logging data of the step movement as a function of time; and

modifying the step length based on at least one of energy, asset orientation, direction, and frequency associated with the step movement.

12. A method in accordance with claim 11, further comprising estimating an asset position with respect to the known location based on cumulative step lengths.

13. A method in accordance with claim 11, further comprising determining whether the step movement is a side step, and ignoring a subsequent step movement when:

the subsequent step movement is in an opposite direction and is a relatively low impact step movement as determined by an energy of the step movement.

14. A method in accordance with claim 11, further comprising calibrating step movement of the asset with respect to the known location.

15. A method in accordance with claim 11, further comprising identifying the step movements using a wavelet derived from compiled average data of a plurality of assets.

16. A method in accordance with claim 15, wherein the wavelet comprises a first amplitude, a second amplitude, and a third amplitude, the second amplitude being a negative amplitude less than the first amplitude and the third amplitude being a greater amplitude than the first amplitude, the wavelet comprising a first inclined portion inclining from the first amplitude to the second amplitude, a declined portion declining from the second amplitude to the third amplitude, and a second inclined portion rising from the third amplitude to the first amplitude.

17. A method in accordance with claim 11, wherein the positional data of the step movement is detected in terms of at least an x-axis and a y-axis, the method further comprising switching the x-axis and the y-axis when the asset is crawling.

18. A method in accordance with claim 11, further comprising reducing back step detection when the asset is moving down stairs.

19. A method in accordance with claim 11, further comprising disallowing backward step detection following a side step detection.

20. A method in accordance with claim 11, wherein the movement detection device comprises a gyroscope and a magnetometer, the method further comprising correcting a gyroscope output based on a magnetometer output at predetermined intervals during substantially straight asset movement

21. A method in accordance with claim 20, further comprising correcting the gyroscope output based on a magnetometer output at a shorter predetermined interval after a turn in asset movement, except when the asset is in a building.

22. A method in accordance with claim 11, further comprising increasing sensitivity to stair step detection if a previous asset movement was a step on a stair.

23. A method in accordance with claim 11, further comprising measuring an energy of the movement of the asset and ignoring the movement if the energy is below a predetermined threshold.

24. A method in accordance with claim 11, further comprising:

establishing a barometric pressure standard using a base barometer;

identifying a vertical position of the asset using an asset barometer; and

correcting the vertical position of the asset for variations in barometric pressure using the barometric pressure standard.

25. A method in accordance with claim 11, further comprising identifying an initial step of the asset using a reverse correlation of the plurality of dimensions of normal walking step movement of the asset.

26. A non-transitory computer readable storage medium having computer readable instructions embodied therein which, when executed by the processor, are operable to:

measure a step length of an asset;

position the asset at a known location;

detect step movement of the asset using a movement detection device;

log data of the step movement as a function of time; and

modify the step length based on at least one of energy, asset orientation, direction, and frequency associated with the step movement.