Optical Tracking Light Intensity Control for Near-Eye Peripherals
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Solution Overview
Problem
Existing optically trackable peripheral devices face challenges in efficiently calibrating light sources, leading to high power consumption and non-uniform brightness, which can impact tracking performance and battery life.
Innovation Solution
The solution involves dynamically controlling the intensity of light sources on a peripheral device based on its pose and movement relative to a computing device. This is achieved by identifying constellations of light sources in image data and adjusting their intensities using pre-calibrated values stored in a calibration table.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If light source intensity is increased to maintain signal quality at greater distances, then tracking reliability is improved, but power consumption increases
Solution Approach 1:
The system dynamically adjusts light source intensity based on real-time tracking conditions, distance to the HMD, and detected signal quality. Rather than using fixed high intensity, the controller modulates brightness adaptively to maintain reliable tracking while minimizing power consumption during periods of good signal quality or when at shorter distances.
Solution Approach 2:
The system changes the intensity parameter of light sources based on measured tracking conditions. A brightness sweep algorithm determines optimal intensity levels, and the controller adjusts light source parameters dynamically based on distance metrics and signal quality feedback, resolving the contradiction between reliability and power consumption.
2Measurement precision
If light source intensity is increased to compensate for distance attenuation, then signal quality is maintained, but pixel saturation occurs at shorter distances
Solution Approach 1:
The system uses dynamic intensity adjustment to prevent pixel saturation. During a brightness sweep, the system identifies the maximum intensity that does not cause saturation at close distances. During tracking, the controller continuously adapts light intensity based on distance to the HMD, ensuring signal quality is maintained without exceeding saturation thresholds.
Solution Approach 2:
The system implements feedback control where the camera detects light source intensity in real-time, and this information feeds back to the controller which adjusts light source brightness accordingly. This closed-loop control prevents pixel saturation by reducing intensity when detected brightness approaches saturation levels, while maintaining signal quality when at greater distances.
3Reliability
If all light sources are illuminated continuously to ensure tracking visibility, then tracking reliability is improved, but power consumption increases
Solution Approach 1:
The system segments the light source population into active and inactive subsets. Rather than illuminating all light sources continuously, the controller selectively activates only those light sources that are currently visible to the HMD camera or likely to enter the field of view based on motion prediction. This segmentation maintains tracking visibility while significantly reducing power consumption from inactive light sources.
Solution Approach 2:
The system uses periodic brightness sweeps to recalibrate and reassess which light sources need to be active. Between sweeps, the controller maintains a reduced set of active light sources based on current tracking conditions. This periodic reevaluation allows the system to adapt to changing conditions while minimizing continuous power consumption.
4Measurement precision
If calibration data is stored for all possible device orientations and positions, then tracking accuracy is improved, but storage requirements increase
Solution Approach 1:
The system extracts only the essential calibration parameters needed for accurate tracking rather than storing complete calibration data for all possible orientations and positions. The brightness sweep algorithm determines key intensity relationships, and the controller uses these extracted parameters to dynamically calculate appropriate light source intensities for unseen orientations through interpolation and geometric relationships.
Solution Approach 2:
The system stores minimal calibration parameters (such as relative intensity ratios and geometric relationships) and dynamically computes full calibration data when needed. Rather than storing extensive lookup tables for all orientations, the controller uses stored parameters to calculate appropriate intensities in real-time based on current device pose, reducing storage requirements 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 reduces power consumption, improves uniformity of light source brightness, and enhances tracking performance by optimizing light source intensity based on the device's position and movement.
Implementation Method 1
each light source emits light within a cone of illumination
Implementation Method 2
A method of determining how to adjust the intensity of each light source includes capturing image data using an image sensor
Data Source
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AI summary
Examples are disclosed that relate to dynamically controlling light sources on an optically trackable peripheral device. One disclosed example provides a near-eye display device comprising an image sensor, a communications subsystem, a logic subsystem, and a storage subsystem. The storage subsystem stores instructions executable by the logic subsystem to control a peripheral device comprising a plurality of light sources by receiving image data from the image sensor, identifying in the image data a constellation of light sources formed by a subset of light sources of the peripheral device, and based upon the constellation of light sources identified, send to the peripheral device via the communications subsystem constellation information related to the constellation of light sources identified.