Wearable Motion Capture Using Sensor Fusion Without External Cameras
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Solution Overview
Problem
Existing full-body motion capture systems are limited in their ability to function in non-controlled environments without external cameras, often requiring expensive equipment, specialized suits, and complex calibration procedures, and they may lose calibration when moved to different areas.
Innovation Solution
A system using five or more trackers with accelerometers, magnetometers, and gyroscopes to determine orientation, combined with a link device that consolidates signals and uses anatomical constraints for interpolation, allowing for portable and untethered motion capture without the need for external cameras or extensive recalibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external cameras and controlled environments are used for motion capture, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The system divides the motion capture functionality into multiple distributed trackers worn on different body parts. Each tracker independently measures local orientation using sensors, and the computing device reconstructs full-body motion by combining these segmented measurements with anatomical constraints, eliminating the need for complex external camera systems.
Solution Approach 2:
The patent replaces the optical-mechanical camera system with an inertial sensing system based on accelerometers, magnetometers, and gyroscopes. This substitution uses field-based sensing (gravitational, magnetic, and rotational fields) instead of mechanical optical tracking, significantly reducing system complexity while maintaining measurement capability.
2Measurement precision
If specialized motion capture suits and equipment are used, then measurement precision is improved, but ease of operation deteriorates
Solution Approach 1:
The system performs automatic calibration by leveraging pre-stored anatomical constraint data and automatically determining tracker positions on the body. The computing device self-calibrates the motion capture system by processing sensor data through anatomical models without requiring manual calibration procedures or specialized suit setup.
Solution Approach 2:
The tracker design integrates multiple sensing functions (acceleration, magnetic field detection, gyroscopic measurement) into a single universal device that can be worn on any body part. This multi-functional tracker replaces multiple specialized components, simplifying operation while maintaining precision through sensor fusion and anatomical constraint-based reconstruction.
3Adaptability or versatility
If the system is moved to different areas, then adaptability is improved, but measurement precision deteriorates due to calibration loss
Solution Approach 1:
The system pre-stores anatomical constraint data representing ideal body segment relationships and performs preliminary automatic calibration when trackers are first placed on the body. This preliminary setup creates a reference framework that remains valid across different environments, allowing the system to maintain precision without recalibration when moved to new locations.
Solution Approach 2:
The system uses sensor fusion that dynamically weights and combines data from accelerometers, magnetometers, and gyroscopes based on current motion conditions. This adaptive parameter weighting allows the system to maintain accurate orientation measurement across varying environmental conditions and locations without requiring recalibration.
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 and continuous full-body motion capture in non-controlled environments, reducing costs and complexity while maintaining high accuracy and eliminating the need for extensive calibration procedures.
Implementation Method 1
an accelerometer
Implementation Method 2
a magnetometer
Implementation Method 3
a gyroscope
Data Source
AI summary
Prior art systems can achieve full-body motion capture without external cameras; however, these systems are often expensive, limit the user's movements to a specified area, require the user to wear a specialized full-body suit, have a high device count, may be fully wired and/or require an energy-intensive WiFi connection. The presently disclosed technology is directed to systems and methods for providing full-body motion capture in non-controlled environments where using multiple known camera perspectives is not possible or practical. Specifically, the presently disclosed technology utilizes at set of trackers to be placed on disparate points of a user's body. A microcontroller for each tracker outputs orientation based on a sensor fusion of outputs. A link consolidates signals from each of the trackers into a singular tracker orientation signal, which is interpolated to determine each tracker's position.