HMD Clock Sync via Magnetic Signal Encoding
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Solution Overview
Problem
Current electromagnetic tracking systems for head-mounted displays (HMDs) face synchronization errors due to differences in real-time clock signals between the HMD and controller devices, leading to inaccuracies in tracking and rendering of virtual controllers, especially when the HMD is in motion.
Innovation Solution
The implementation uses a magnetic emitter on the HMD to emit a synchronized magnetic signal that encodes the HMD's real-time clock value, which is detected by the controller's magnetic sensor, allowing for synchronization of the controller's clock with the HMD's clock, ensuring accurate timing and position data for immersive virtual reality experiences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electromagnetic tracking systems use separate real-time clock signals for HMD and controller devices, then each device can operate independently, but synchronization errors occur leading to tracking inaccuracies
Solution Approach 1:
The patent introduces a magnetic field as an intermediary carrier to transmit timing information from the HMD to the controller. The magnetic emitter on the HMD generates a magnetic field that encodes timing data, which the controller's magnetic sensor detects. This intermediary magnetic field mechanism enables precise clock synchronization between the two devices without requiring direct electrical connection or shared clock signals, thereby resolving the synchronization precision issue while maintaining tracking accuracy.
2Adaptability or versatility
If the HMD is in motion, then the user experience is more immersive, but tracking errors increase due to clock desynchronization
Solution Approach 1:
The system implements a feedback mechanism where the HMD continuously emits magnetic signals containing timing information, and the controller continuously detects these signals to adjust its clock in real-time. This closed-loop feedback ensures that even during rapid user movement, the controller's clock remains synchronized with the HMD's clock, maintaining tracking stability and reliability while allowing full user mobility for immersive experiences.
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 solution achieves precise synchronization of the HMD and controller clocks, reducing tracking errors and providing a more stable and accurate rendering of virtual controllers, even during user movement, thereby enhancing the overall virtual reality experience.
Implementation Method 1
a magnetic emitter on the HMD to emit a synchronized magnetic signal that encodes the HMD's real-time clock value, which is detected by the controller's magnetic sensor
Data Source
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AI summary
A system, including: a computing device that executes an interactive application and generates and transmits image frames; a head-mounted display (HMD) that receives and presents the image frames, wherein the HMD includes a magnetic emitter that emits a magnetic signal having a synchronization encoding synchronized to the received image frames; a controller device that includes a magnetic sensor that detects the magnetic signal, wherein the controller device processes the detected magnetic signal to determine magnetic position data and read the synchronization encoding, wherein the controller device uses the synchronization encoding to generate corresponding timing data indicating a timing of the magnetic position data based on the synchronization encoding, wherein the controller device transmits the magnetic position data and the corresponding timing data to the computing device; wherein the computing device uses the magnetic position data and the corresponding timing data to determine the location and/or orientation of the controller device.