Hybrid orthogonal localization and orientation system

• US 5,422,715 A
• Filed: 03/11/1993
• Issued: 06/06/1995
• Est. Priority Date: 03/11/1993
• Status: Expired due to Fees

• Current Assignee: Thomas L. Clarke
• Original Assignee: Thomas L. Clarke
• Inventors: Clarke, Thomas L.
• Primary Examiner(s): Limanek, Robert
• Assistant Examiner(s): Hardy, David B.
• Application Number:
  US08/029,538
• Time in Patent Office: 817 Days
• Field of Search: 356/375, 356/139.03, 356/141.1, 356/141.3, 356/141.4, 356/141.5, 356/373, 250/206.2, 250/206.3
• US Class Current: 356/141.3
• CPC Class Codes: G01C 15/002 Active optical surveying means optical plumbing G01C15/105
• CPC Class Codes: G01S 1/7038 Signal details
• CPC Class Codes: G01S 5/16 using electromagnetic waves other than radio waves

Abstract

An improved device for determining the three-dimensional location and orientation of a subject in a virtual reality simulation is a hybrid of an optical localization system and independent tilt and direction sensors. Three or more modulated sources of light or near-infrared radiation are placed at the perimeter of the sensing volume; these sources are typically emitters surrounded by rotating cylindrical grating. A single photosensor extracts enough information from the radiation field to derive position within the volume. Orientation is sensed by small gravitational tilt and magnetic compass direction sensors. Since the sensing is entirely passive, any number of objects can be tracked within the volume as long as at least three of the sources are visible from the position of each object.

Claims

1. A system for measuring spatial location comprising a radiant energy sensor, three or more radiant energy emitters, means imposing a rotating intensity pattern on said emitters, means modulating said emitters with a modulated signal unique to each emitter and phase-locked to the intensity rotation pattern of each emitter, signal processing means extracting amplitude modulation of said unique signals from the output of said optical sensor and extracting said modulated signals from said optical sensor, and means measuring a phase shift between said extracted amplitude modulation and said extracted modulated signal.

2. A system for measuring spatial location as specified in claim 1 with additional means measuring orientation with respect to a local gravitational vertical and means measuring direction with respect to the earth'"'"'s magnetic field.

3. A system for measuring spatial location as specified in claim 1 with an electrolytic sensor measuring tilt, and a flux gate compass determining direction with respect to the earth'"'"'s magnetic field.

4. A system for measuring spatial location as specified in claim 1 with an electrolytic sensor measuring tilt, and Hall-effect sensors determining direction with respect to the earth'"'"'s magnetic field.

5. A system for measuring spatial location comprising a radiant energy sensor, three or more radiant energy emitters, a rotating cylindrical grating surrounding each emitter, reference radiant energy detectors adjacent to each cylindrical grating, means for generating a periodic signal of unique frequency energizing each emitter, electronic circuitry varying a phase of said periodic signal in response to said corresponding radiant energy detector, amplification and filtering separating the unique periodic signal associated with each emitter from said radiant energy sensor output, means detecting an amplitude modulation of each filtered signal, means detecting a phase modulation of each filtered signal, and means measuring a phase shift between an intensity modulation and said phase modulation detected from each filtered signal.

6. A system for measuring spatial location as specified in claim 5 with additional means measuring orientation with respect to a local gravitational vertical and means measuring direction with respect to the earth'"'"'s magnetic field.

7. A system for measuring spatial location as specified in claim 5 with an electrolytic sensor measuring tilt, and a flux gate compass determining direction with respect to the earth'"'"'s magnetic field.

8. A system for measuring spatial location as specified in claim 5 with an electrolytic sensor measuring tilt, and Hall-effect sensors determining direction with respect to the earth'"'"'s magnetic field.

9. A system for measuring spatial location comprising a photosensor, three or more light-emitting-diodes, a rotating cylindrical grating surrounding each light-emitting-diode, reference photodetectors adjacent to each cylindrical grating, means for generating a periodic signal with unique frequency energizing each light-emitting-diode, electronic circuitry varying a phase of said periodic signal in response to said corresponding reference photodetector, amplification and filtering means separating the unique periodic signal associated with each light-emitting-diode from said photosensor output, means detecting an amplitude modulation of each filtered signal, means detecting a phase modulation of each filtered signal, and means measuring a phase shift between a intensity modulation and said phase modulation detected from each filtered signal.

10. A system for measuring spatial location as specified in claim 9 with additional means measuring orientation with respect to a local gravitational vertical and means measuring direction with respect to the earth'"'"'s magnetic field.

11. A system for measuring spatial location as specified in claim 9 with an electrolytic sensor measuring tilt, and a flux gate compass determining direction with respect to the earth'"'"'s magnetic field.

12. A system for measuring spatial location as specified in claim 9 with an electrolytic sensor measuring tilt, and Hall-effect sensors determining direction with respect to the earth'"'"'s magnetic field.