Intertial tracking system with provision for position correction

• US 8,825,435 B2
• Filed: 02/22/2011
• Issued: 09/02/2014
• Est. Priority Date: 02/19/2010
• Status: Expired due to Fees

• Current Assignee: Hailo Technologies, LLC (2S Ventures, LLC)
• Original Assignee: iTrack LLC
• Inventors: Smid, G. Edzko, Stiglich, Thomas P.
• Primary Examiner(s): Breene, John
• Assistant Examiner(s): Zhang, Ruihua
• Application Number:
  US13/031,933
• Publication Number:
  US 20110313716A1
• Time in Patent Office: 1,288 Days
• Field of Search: 702/85, 702/150, 702/155, 702/94, 702/141, 702/101, 702/151, 701/517, 701/519, 734/88, 342/165, 74/13.7, 744/88
• US Class Current: 702/141
• CPC Class Codes: G01C 21/1652 with ranging devices, e.g. LIDAR or RADAR

Abstract

A subject location tracking process is provided that includes the attachment of a system to a subject where the system includes a radiofrequency sensor integration module, an inertial tracking module, and a microprocessor. Radiofrequency signals are communicated from the radiofrequency sensor integration module to a remote radiofrequency transceiver beacon. A measured range is determined between the radiofrequency sensory integration module and the beacon. An error value E is then computed between the measured range and a predicted range. The predicted range is computed from the inertial tracking module alone based on positional data as to location and orientation of the system. The location data of the subject is determined with a microprocessor and displayed at the location. The present invention operates to provide a high degree of accuracy as to the position of a subject in spite of intermediate obstructions and without reliance on global position satellite systems, fixed reference signals, or line of sight.

Claims

1. A subject location tracking process comprising:

communicating radiofrequency signals from a radiofrequency sensory integration module with a remote RF transceiver beacon, said radiofrequency sensory integration module forming a system with an ankle mounted inertial tracking module and a microprocessor, and operative without line of sight with said remote RF transceiver beacon;

determining a measured range between said radiofrequency sensory integration module and said beacon with software in said radiofrequency sensory integration module;

accessing a database of known positions for the beacon to estimate a predicted range;

computing an error value between the measured range and the predicted range, or between said radiofrequency signals and a predicted range, wherein positional data as to location of the system from said inertial tracking module is used to compute the predicted range;

communicating a corrected position to said inertial tracking module to aid in resetting or correcting an orientation value or a velocity values as generated by an inertial module sensor within said inertial tracking module;

adding a weighing factor to the measured range based on the error prior to determining the location data for the subject by trilaterating the location of the subject target;

determining location data of the subject with said microprocessor and displaying the location; and

wherein said microprocessor processes sets of data being generated in tandem by said radiofrequency sensory integration module and an inertial sensor in said inertial tracking module to form a mutually corrective system.

2. The process of claim 1 wherein said inertial module sensor provides acceleration values for the subject.

3. The process of claim 2 wherein the acceleration values are transformed into orientation values and then velocity values.

4. The process of claim 1 wherein the beacon conveys the location data.

5. The process of claim 1 wherein the location data is displayed to the subject.

6. The process of claim 1 wherein said inertial module sensor is at least one of a gyroscope and an accelerometer.

12. The process of claim 1 further comprising said inertial module sensor is amenable to mounting on a waist, torso, or head of an animate subject and any portion on an inanimate subject that is coupled to a periodic movement during translation.

13. The process of claim 1 wherein said inertial module sensor are a 2D accelerometer and a single axis gyroscope that are arranged to model said subject'"'"'s navigation as a 2D problem by approximating the subject'"'"'s leg movement as being a motion that is constrained to the x,z-plane.

14. The process of claim 13 wherein a set of signals coming from said inertial module sensor are first stored in a signal memory, while features of the signals are identified that can be used for step detection by a step detector;

and

wherein said step detector determines the beginning and end of a step, which is used to retrieve acceleration and gyro signals during the step from the signal memory for further processing.

15. The process of claim 14 wherein said processing further comprises first an estimation of an orientation of said inertial module sensor with respect to a world frame, said orientation estimation being based on an assumption that the velocity at the beginning of the step and the end of the step is equal to zero;

and

wherein the calculated orientations are used to transform the acceleration signals from a body-frame to the world frame and doubly integrated to update the position of said subject.

7. A subject location tracking process comprising:

communicating radiofrequency signals from a radiofrequency sensory integration module with a plurality of remote RF transceiver beacons, said radiofrequency sensory integration module forming a system with an ankle mounted inertial tracking module and a microprocessor, and operative without line of sight with said plurality of remote RF transceiver beacons;

determining a measured range between said radiofrequency sensory integration module and said plurality of beacons with software in said radiofrequency sensory integration module;

accessing a database of known positions for the beacon to estimate a predicted range;

computing an error value between the measured range and a predicted range, or between said radiofrequency signals and the predicted range, wherein positional data as to location and orientation of the system from said inertial tracking module is used to compute the predicted range;

communicating a corrected position to said inertial tracking module to aid in resetting or correcting an orientation value or a velocity values as generated by an inertial module sensor within said inertial tracking module;

adding a weighing factor to the measured range based on the error prior to determining the location data for the subject;

by trilaterating the location of the subject target;

determining location data of the subject with said a microprocessor and displaying the location; and

wherein said microprocessor processes sets of data being generated in tandem by said radiofrequency sensory integration module and an inertial sensor in said inertial tracking module to form a mutually corrective system.

8. The process of claim 7 wherein said inertial module sensor provides acceleration values for the subject.

9. The process of claim 8 wherein the acceleration values are transformed into orientation values and then velocity values.

10. The process of claim 7 wherein the location data is displayed to the subject.

11. The process of claim 7 wherein said inertial module sensor is at least one of a gyroscope and an accelerometer.