System and method for object tracking anti-jitter filtering

• US 9,404,994 B2
• Filed: 06/18/2015
• Issued: 08/02/2016
• Est. Priority Date: 11/12/2012
• Status: Active Grant

• Current Assignee: IsoLynx LLC
• Original Assignee: IsoLynx LLC
• Inventors: DeAngelis, Douglas J., Reilly, Gerard M., Sigel, Kirk M., Evansen, Edward G.
• Primary Examiner(s): Huynh, Phuong
• Application Number:
  US14/743,525
• Publication Number:
  US 20150285894A1
• Time in Patent Office: 411 Days
• US Class Current: 1/1
• CPC Class Codes: A63B 2024/0025 Tracking the path or location of one or more users, e.g. players of a game
• CPC Class Codes: G01S 11/02 using radio waves G01S19/00 takes precedence
• CPC Class Codes: G01S 5/0018 Transmission from mobile station to base station
• CPC Class Codes: G01S 5/0036 of measured values, i.e. measurement on mobile and position calculation on base station
• CPC Class Codes: G01S 5/0294 Trajectory determination or predictive filtering, e.g. target tracking or Kalman filtering

Abstract

Object tracking anti-jitter filtering systems and methods. A plurality of raw location points for a tracking tag attached to a tracked object is received. The raw location points are stored within a raw location points buffer. Raw location points within an averaging window are averaged to generate an averaged location point. The averaged location point is stored within an averaged location points buffer for use within the object tracking system.

Claims

1. Object tracking anti-jitter filtering method, comprising:

receiving, within an object tracking system, a plurality of raw location points for a tracking tag attached to a tracked object;

storing the plurality of raw location points within a raw location points buffer;

averaging ones of the raw location points received within an averaging period to generate an averaged location point;

storing the averaged location point within an averaged location points buffer for use within the object tracking system; and

dynamically adjusting the duration of the averaging period to include a desired number of the raw location points within the averaging period.

2. The method of claim 1, further comprising positioning a center of the averaging period at a fixed delay from the latest received raw location point.

3. The method of claim 2, wherein the center of the averaging period is at a same fixed delay, from the most recently stored raw location point, before and after the step of dynamically adjusting.

4. The method of claim 1, the step of dynamically adjusting comprising:

for each generated average location point;

determining a speed of the object based upon most recent of the generated averaged location points; and

increasing the desired number of raw location points by a low points adjust value if the speed is less than a predefined low speed threshold.

5. The method of claim 1, the step of dynamically adjusting comprising:

for each generated average location point;

determining a speed of the object based upon most recent of the generated averaged location points; and

decreasing the desired number of raw location points by a high points adjust value if the speed is greater than a predefined high speed threshold.

6. The method of claim 1, further comprising:

if there are no raw location points within the averaging period and a latest speed of the tracked object is greater than a predefined high speed threshold;

generating a projected location point based upon a determined direction of movement of the tracked object and a determined projection speed of the tracked object, wherein the direction and the projection speed are determined from previous two averaged location points; and

storing the projected location point within the averaged location points buffer.

7. The method of claim 6, further comprising:

if there are no raw location points within the averaging period and a projection interval is greater than a maximum projection interval;

if the projection speed is greater than zero, reducing the projection speed for each subsequently generated projection point;

wherein the projection interval is a cumulative period of consecutively generated projection location points.

8. The method of claim 7, further comprising:

determining, from averaged location points determined for the tracking tag and for at least one additional tracking tag attached to the tracked object, an object location of the tracked object based upon positions of the tracking tags relative to one another and relative to the tracked object; and

if one of the averaged location points is missing, correcting the object location based upon an orientation of the tracked object and a distance between the tracking tag associated with the missing average location point and an average position of all tracking tags;

wherein the orientation is determined from at least one average location point from each of the tracking tags.

9. The method of claim 8, further comprising:

determining a current acceleration of the tracked object based upon three most recently determined average location points; and

if one or more of the latest speed and the current acceleration are greater than maximum physical characteristics of the tracked object, correcting the most recent average location point based upon the maximum physical characteristics.

10. Object tracking anti-jitter filtering system, comprising:

at least one processor;

memory coupled with the processor for storing raw location points of a tracked object;

an averaging filter comprising machine readable instructions stored within the memory and executed by the processor to generate an averaged location point having reduced jitter when compared to the raw location points by averaging a desired number of raw location points within an averaging window; and

,

a points based period controller comprising machine readable instructions stored within the memory and executed by the processor to incrementally increase the desired number of raw location points within the averaging window when a latest speed of the tracked object is less than a predefined low speed threshold, and to incrementally decrease the desired number of raw location points within the averaging window when the latest speed is greater than a predefined high speed threshold.

11. The system of claim 10, the point based controller further comprising machine readable instructions stored within the memory and executed by the processor to determine the latest speed of the tracked object from the two most recently generated averaged location points.

12. The system of claim 10, averaging filter comprising machine readable instructions stored within the memory and executed by the processor to determine a period of the averaging window based upon the desired number of raw location points within the averaging window.

13. The system of claim 12, the point based controller further comprising machine readable instructions stored within the memory and executed by the processor to position a center of the averaging window at a fixed delay from the latest stored raw location point.

14. The system of claim 10, further comprising:

a speed based projection filter, comprising machine readable instructions stored within the memory and executed by the processor, for generating the averaged location point based upon at least two previously generated average location points for the tracking tag using a projection technique when a latest speed of the tracked object is greater than a predefined high speed threshold and the averaging window contains not received raw location points.

15. The system of claim 14, wherein the projection technique comprises at least one projection technique chosen from the group consisting of:

weighted averaging, linear interpolation, piecewise interpolation, polynomial interpolation, and curve fitting.

16. The system of claim 10, further comprising:

a multi-tag correction filter, comprising machine readable instructions stored within the memory and executed by the processor, for correcting an object location, determined by averaging the location of a plurality of tracking tags attached to the tracked object, towards the location of one tracking tag for which averaged location points are missing.

17. The system of claim 16, further comprising:

a physical limit filter, comprising machine readable instructions stored within the memory and executed by the processor, for adjusting the averaged location point when one or both of a latest speed of the tracked object and an acceleration of the tracked object exceeds maximum physical characteristics of the tracked object;

wherein the averaged location point is set to a location, relative to a previous averaged location point, that is within the maximum physical characteristics.

18. Object tracking anti-jitter filtering method, comprising:

receiving, at predetermined intervals and within an object tracking system, a plurality of raw location points for a tracking tag attached to a tracked object;

storing the plurality of raw location points within a raw location points buffer;

averaging a plurality of the raw location points received within an averaging period window to generate an averaged location point, wherein the center of the averaging period window is located at a position within the stored raw location points representing a fixed time delay from the latest stored raw location point; and

dynamically adjusting the size of the averaging period to include a desired number of the raw location points within the averaging period such that the center of the averaging period window is maintained at the position.

19. The method of claim 18, the step of dynamically adjusting including identifying that a raw location point was not received at one of the predetermined intervals and adjusting the size of the averaging period in response thereto.

20. The method of claim 18, the step of dynamically adjusting comprising:

for each generated average location point;

determining a speed of the object based upon most recent of the generated averaged location points; and

increasing the desired number of raw location points by a low points adjust value if the speed is less than a predefined low speed threshold.

21. The method of claim 18, the step of dynamically adjusting comprising:

for each generated average location point;

determining a speed of the object based upon most recent of the generated averaged location points; and

decreasing the desired number of raw location points by a high points adjust value if the speed is greater than a predefined high speed threshold.

22. The method of claim 18, further comprising:

if there are no raw location points within the averaging period and a latest speed of the tracked object is greater than a predefined high speed threshold;

generating a projected location point based upon a determined direction of movement of the tracked object and a determined projection speed of the tracked object, wherein the direction and the projection speed are determined from previous two averaged location points; and

storing the projected location point within the averaged location points buffer.

23. The method of claim 22, further comprising:

if there are no raw location points within the averaging period and a projection interval is greater than a maximum projection interval;

if the projection speed is greater than zero, reducing the projection speed for each subsequently generated projection point;

wherein the projection interval is a cumulative period of consecutively generated projection location points.

24. The method of claim 23, further comprising:

determining, from averaged location points determined for the tracking tag and for at least one additional tracking tag attached to the tracked object, an object location of the tracked object based upon positions of the tracking tags relative to one another and relative to the tracked object; and

if one of the averaged location points is missing, correcting the object location based upon an orientation of the tracked object and a distance between the tracking tag associated with the missing average location point and an average position of all tracking tags;

wherein the orientation is determined from at least one average location point from each of the tracking tags.

25. The method of claim 24, further comprising:

determining a current acceleration of the tracked object based upon three most recently determined average location points; and

if one or more of the latest speed and the current acceleration are greater than maximum physical characteristics of the tracked object, correcting the most recent average location point based upon the maximum physical characteristics.