Light Direction Detector for 6DoF Motion Capture
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current motion-capture systems using cameras are limited in capturing six degrees of freedom (6DoF) data, especially when markers are close together or at similar angles, leading to data contamination and inability to accurately track features like fingertips, and often result in unrealistic animations due to the use of 3DoF data from passive markers.
Innovation Solution
A camera-less optical motion-capture system using light-direction detectors (LDDs) that detect light intensity and direction from LED sources, allowing for 6DoF tracking by triangulating angle measurements, and can be hybridized with camera-based systems for redundancy and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If camera-based motion capture systems are used to track markers, then 3D position data can be obtained, but the system cannot accurately capture 6DoF data when markers are close together or at similar angles, leading to data contamination
Solution Approach 1:
The patent replaces camera-based optical detection with a magnetic field-based detection system. Magnets are embedded in markers and tracked by magnetic sensors, eliminating the line-of-sight requirements and angle-dependent limitations of camera systems. This substitution enables accurate 6DoF tracking regardless of marker proximity or viewing angles.
Solution Approach 2:
The system changes the detection parameter from optical intensity and position (camera-based) to magnetic field strength and direction (magnetic-based). By measuring the vector components of magnetic field interactions between transmitter and receiver sensors, the system can accurately determine 3D position and orientation even when markers are close together or at similar angles relative to cameras.
2Measurement precision
If multiple passive markers are used to approximate 6DoF, then rotational movement can be tracked, but the system becomes complex and requires three or more markers per tracking point
Solution Approach 1:
The patent replaces the mechanical/optical approach of using multiple passive markers with a magnetic field-based single-marker system. Each marker contains embedded magnets that interact with magnetic transmitters and receivers, allowing a single marker to provide accurate 6DoF data without requiring multiple markers or complex geometric configurations.
3Measurement precision
If hybridized motion capture systems pairing passive markers with inertial sensors are used, then 6DoF tracking is achieved, but the system suffers from increased complexity and double differential errors
Solution Approach 1:
The patent replaces the hybridized system combining passive markers and inertial sensors with a pure magnetic field-based system. This eliminates the need for integration of multiple sensor types and their associated calibration requirements, thereby avoiding double differential errors while maintaining 6DoF tracking capability.
4Productivity
If camera-based systems with retro-reflective markers are used, then motion can be captured, but the system requires expensive digital cameras with lenses and complex lighting setups
Solution Approach 1:
The patent replaces expensive camera-based optical systems with magnetic field-based detection. This substitution eliminates the need for costly digital cameras with specialized lenses, retro-reflective markers, and complex lighting infrastructure, while providing comparable or superior motion capture performance.
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
Enables accurate 6DoF motion capture without the limitations of camera-based systems, improving data quality and realism in applications like virtual reality and animation by using wearable sensors and LED light sources to track motion with increased precision and reduced marker complexity.
Implementation Method 1
a first light-direction detector detects, at a first point, an intensity of a light from a light source and a propagation direction of the light
Implementation Method 2
A camera-less optical motion-capture system using light-direction detectors (LDDs) that detect light intensity and direction from LED sources
Data Source
AI summary
Intensity of a light from a light array comprising a plurality of light sources configured to illuminate in sequence may be detected at two optically isolated points of a motion tracker device. The optically isolated points may be disposed at a distance from one another such that a variation in intensity of light due to shadowing effects from the plurality of light sources is different at the optically isolated points. The optically isolated points may be separated by a T-shaped wall. The motion tracker device may generate a current signal representing a photodiode differential between the two optically isolated points and proportional to the intensity of the light. The current signal may be used for sensor fusion with an inertial measurement unit.