Polarized tracker system and method for tracking movement
A system and method are provided for leveraging emitted polarized electromagnetic radiation as a means to track relative orientation and position of an object with regard to another object. Six basic degrees of freedom including three angular and three translational are determined based on making multiple polarization-based measurements and then determining the corresponding geometry that would yield those measurements.
1. A method for tracking an object in relation to a platform, comprising:
transmitting polarized electromagnetic radiation from a plurality of emitters, the emitters affixed to one of the object and the platform, the object having a plurality of degrees of freedom relative to the platform;
receiving the polarized electromagnetic radiation by a plurality of polarized detectors affixed to the other of the object and the platform;
measuring polarized electromagnetic radiation levels of the polarized electromagnetic radiation received by the plurality of polarized detectors; and
analyzing the received polarized electromagnetic radiation levels to determine a set of angles of the object relative to the platform.
2. The method of claim 1 further comprising positioning the object proximate a person's head.
3. The method of claim 2 further comprising:
determining information based on the set of angles; and
displaying the information on a near-to-eye display associated with the object.
4. The method of claim 1 wherein the transmitting further comprises transmitting from emitters affixed to both the object and the platform, and the receiving comprises receiving by detectors affixed to both the object and the platform.
5. The method of claim 1 wherein the transmitting comprises transmitting through a plurality of uniaxial polarizers, wherein axes of the polarizers are not parallel and are not coplanar.
6. The method of claim 1 wherein the analyzing comprises converting the measured polarized electromagnetic radiation levels into at least six degrees of freedom including three angular degrees of freedom and three linear degrees of freedom.
7. The method of claim 1 wherein the analyzing comprises an oversampled numerical fit for averaging out noise.
8. The method of claim 1 wherein analyzing comprises varying a computational algorithm based on detected rate of object motion.
9. The method of claim 1 further comprising normalizing the analyzed polarized electromagnetic radiation levels by comparing results from a non-polarized detector for minimizing the effects of angular and spatial rolloffs.
10. A tracking system, comprising:
a first object;
a second object;
a plurality of emitters affixed to one of the first object and the second object, and configured to transmit polarized electromagnetic radiation;
a plurality of detectors affixed to the other of the first object and the second object; and
a processor coupled to the detectors and configured to:
receive data from the detectors indicative of polarized electromagnetic radiation received by the detectors; and
analyze the data to determine a set of angles of the first object relative to the second object.
11. The tracking system of claim 10 wherein the movement tracking system further comprises:
an apparatus affixed to the first object and configured to be positioned on a person's head.
12. The tracking system of claim 11 wherein the processor is further configured to:
determine information based on the set of angles; and
display the information on the first object.
13. The tracking system of claim 10 wherein the emitters are affixed to both the first object and the second object.
14. The tracking system of claim 10 wherein the detectors are affixed to both the first object and the second object.
15. The tracking system of claim 10 wherein the emitters are configured to:
transmit through a plurality of polarizers having a plurality of axis orientations.
16. The tracking system of claim 10 wherein the processor is further configured to:
convert the measured polarized electromagnetic radiation levels into at least six degrees of freedom including at least three angular and three linear.
17. The tracking system of claim 10 wherein the processor is further configured to determine an oversampled numerical fit for averaging out noise.
18. The tracking system of claim 11 wherein the processor is further configured to:
vary a computational algorithm to optimize at least one of precision and accuracy when object motion is minimal or slow, and to favor low latency in the case of rapid head motion.
19. The tracking system of claim 10 wherein the processor is further configured to:
normalize the analyzed polarized electromagnetic radiation levels by comparing results from a non-polarized detector for minimizing the effects of angular and spatial rolloffs.
20. The tracking system of claim 10 wherein the detectors comprise:
a polarizing structure associated with each of the detectors.
21. The tracking system of claim 10 wherein the emitters comprise:
a polarizing structure associated with each of the emitters.
22. The tracking system of claim 10 further comprising:
a plurality of non-polarized detectors affixed to the other of the first object and the second object and configured to receive the polarized electromagnetic radiation; and wherein the processor is further configured to:
compare results from non-polarized detectors and the detectors, using normalized ratios to minimize the effects of angular and spatial rolloffs.
23. The tracking system of claim 10 wherein the processor is further configured to:
reduce noise due to ambient electromagnetic radiation by phase-sensitive detection and averaging algorithms.
24. The tracking system of claim 10 wherein the processor is further configured to:
utilize temporal characteristics of the measured levels.
25. The tracking system of claim 10 further comprising a tracking device coupled to the processor, wherein the processor is further configured to:
compare an output of the tracking device with the data; and
modify the data based on the comparison.
26. The tracking system of claim 10 further comprising:
a polarization rotating element associated with at least one of the emitters or one of the detectors.
27. The tracking system of claim 10 further comprising:
pulse-encoding the polarized electromagnetic radiation.
28. A tracking system, comprising:
a first object;
a second object;
a plurality of emitters affixed to one of the first object and the second object;
a plurality of detectors affixed to the other of the first object and the second object; and
a processor coupled to the emitters and the detectors and configured to:
instruct the emitters to transmit polarized electromagnetic radiation;
receive data from the detectors indicative of polarized electromagnetic radiation received by the detectors; and
analyze the data to determine a set of angles of the first object relative to the second object.