VR Hand Controller Tracking Using HMD Diffuse LED Signals
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Solution Overview
Problem
Conventional VR systems require external systems with fixed transmitters and high-bandwidth sensors for accurate tracking of hand controllers, which are costly and sensitive to optical noise, and need large spaces for operation.
Innovation Solution
The system uses diffuse electromagnetic radiation from LEDs in the HMD, detected by photodiodes in the hand controller, to determine position and orientation with sub-millimeter accuracy, eliminating the need for external transmitters and high-bandwidth sensors, and incorporating novel circuitry to reduce sensitivity to external light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external systems with fixed transmitters and high-bandwidth sensors are used for tracking, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
Instead of having external transmitters emit signals that sensors detect, the patent inverts the approach by placing LEDs in the HMD that emit signals detected by photodiodes in the hand controller. This reversal eliminates the need for external transmitter systems and reduces overall system complexity while maintaining tracking precision.
Solution Approach 2:
The HMD serves dual purposes: it not only displays virtual reality content but also functions as the signal source for tracking. The LEDs integrated into the HMD provide both illumination for the display and tracking signals, eliminating the need for separate external transmitter systems.
2Measurement precision
If high-bandwidth sensors are used for accurate tracking, then measurement precision is improved, but sensitivity to optical noise increases
Solution Approach 1:
The LEDs in the HMD emit light in periodic pulse sequences rather than continuously. This periodic emission allows the photodiodes to detect signals at specific time intervals, enabling the system to distinguish between intentional tracking signals and random optical noise, thereby reducing noise sensitivity.
Solution Approach 2:
The system uses LEDs that emit at specific wavelengths and employs photodiodes tuned to detect those particular wavelengths. By using wavelength-specific detection, the system can filter out optical noise at other wavelengths, reducing sensitivity to harmful optical interference while maintaining tracking precision.
3Measurement precision
If fixed transmitters are used for tracking, then measurement precision is improved, but the space required for operation increases
Solution Approach 1:
The patent combines the transmitter function into the portable HMD device itself rather than using separate fixed external transmitters. This merging allows the tracking system to operate without requiring large spaces for external equipment, making the system suitable for smaller or more confined environments while maintaining tracking accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for accurate tracking of hand controllers with reduced costs and space requirements, while minimizing sensitivity to optical noise, enabling precise position and orientation determination within VR systems.
Implementation Method 1
diffuse electromagnetic radiation from LEDs in the HMD, detected by photodiodes in the hand controller
Data Source
Figure 1A
Figure 1B
Figure 1C~1D
AI summary
Techniques of tracking a hand controller in a VR system involves detecting, by photodiodes in the hand controller, patterns of diffuse radiation generated by diffuse LEDs in the HMD. Such techniques can also include comparing the detected patterns to those simulated offline previously and represented in a lookup table (LUT). By looking up the detected patterns in the LUT, the VR system may determine the position and/or orientation of the hand controller with sub-millimeter accuracy. Some advantages of the improved techniques can be in the simplicity and/or low cost of the components without sacrificing accuracy in deriving the position and orientation of the hand controller.