Variable step tracking

• US 9,170,124 B2
• Filed: 09/19/2011
• Issued: 10/27/2015
• Est. Priority Date: 09/17/2010
• Status: Expired due to Fees

• 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.
• Primary Examiner(s): HENSON, MISCHITA L
• Application Number:
  US13/236,522
• Publication Number:
  US 20120239333A1
• Time in Patent Office: 1,499 Days
• US Class Current: 1/1
• 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 system, 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 step length database for storing a step length of the asset;

a step length modification device 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 in the step length modification device for estimating an asset position with respect to a known location based on cumulative step lengths, the processor being further configured to use a wavelet to identify the step movement of the asset or to identify the at least one of energy, asset orientation, direction, and frequency associated with the step movement;

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;

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; and

the change in direction is a change in direction from one direction selected from forward, backward or sideward directions to a different direction selected from forward, backward or sideward directions.

2. The system of claim 1, wherein the first and second declined portions and the inclined portion respectively comprise straight, linear segments.

3. The system of claim 1, wherein the first and second declined portions and the inclined portion comprise non-straight segments.

4. The system of claim 1, wherein if 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.

5. The system 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.

6. The system of claim 5, wherein 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.

7. The system of claim 6, wherein the at least one movement detection device is comprised of at least one accelerometer, gyroscope, barometer, altimeter, and/or magnetometer.

8. A computing device that is configured to perform variable step tracking, comprising:

a processor,

a memory in electronic communication with the processor;

instructions stored in the memory, the instructions being executable by the processor 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;

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

identify the step movements using a wavelet derived from compiled average data of a plurality of assets; and

perform one or more of;

reducing back step detection sensitivity when the asset is moving down stairs;

or

increasing sensitivity to stair step detection if a previous asset movement was a step on a stair.

9. A computing device in accordance with claim 8, further configured to estimate an asset position with respect to the known location based on cumulative step lengths.

10. A computing device in accordance with claim 8, further configured to determine 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.

11. A computing device in accordance with claim 8, further configured to calibrate step movement of the asset with respect to the known location.

12. A computing device in accordance with claim 8, 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.

13. A device in accordance with claim 8, wherein positional data of the step movement is detected in terms of at least an x-axis and a y-axis, the computing device being further configured to switch the x-axis and the y-axis when the asset is crawling.

14. A computing device in accordance with claim 8, further configured to reduce back step detection sensitivity when the asset is moving down stairs.

15. A computing device in accordance with claim 8, further configured to backward step detection following a side step detection.

16. A computing device in accordance with claim 8, wherein the movement detection device comprises a gyroscope and a magnetometer, the computing device being further configured to correct a gyroscope output based on a magnetometer output at predetermined intervals during substantially straight asset movement.

17. A computing device in accordance with claim 16, further configured to correct 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.

18. A comuputing device in accordance with claim 8, further configured to increase sensitivity to stair step detection if a previous asset movement was a step on a stair.

19. A computing device in accordance with claim 8, further configured to measure an energy of the movement of the asset and ignoring the movement if the energy is below a predetermined threshold.

20. A computing device in accordance with claim 8, further configured to:

establish a barometric pressure standard using a base barometer;

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

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

21. A computing device in accordance with claim 8, further configured to identify an initial step of the asset using a reverse correlation of a plurality of dimensions of normal walking step movement of the asset.

22. A variable step tracking computing device, comprising:

a processor,

a memory in electronic communication with the processor;

instructions stored in the memory, the instructions being executable by the processor 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;

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

perform one or more of;

measuring an energy of the movement of the asset and ignoring the movement if the energy is below a predetermined threshold;

disallowing backward step detection following a side step detection;

or

identifying an initial step of the asset using a reverse correlation of a plurality of dimensions of normal walking step movement of the asset;

wherein detection of the step movement of the asset uses a wavelet derived from compiled average data of a plurality of assets.