UWB Motion Capture via Distance Matrix Reconstruction
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Solution Overview
Problem
Existing motion capture technologies, particularly optical systems, are costly and require controlled environments, limiting their accessibility and usability for a wider range of applications and users.
Innovation Solution
The use of ultra-wideband (UWB) tags coupled to a body to construct a distance matrix, reconstructing a skeletal topology based on 3D positions, and repeating this process to capture motion, which simplifies setup and computation, and allows for motion capture without the need for a stationary node or kinematic model.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical systems are used for motion capture, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces complex optical sensing systems with ultra-wideband (UWB) radio frequency tags and anchors. Instead of using optical cameras and sensors that require controlled environments, the system uses UWB tags attached to body segments that communicate with UWB anchors to determine 3D positions through time-of-flight measurements. This substitution of optical systems with radio frequency systems reduces device complexity and cost while maintaining motion capture functionality
Solution Approach 2:
The patent extracts the motion capture functionality from complex optical systems and implements it through simplified UWB tag-anchor pairs. Each body segment is equipped with a UWB tag that independently communicates with UWB anchors to determine its position, eliminating the need for centralized optical sensing infrastructure. This extraction approach reduces overall system complexity while preserving measurement capabilities
2Measurement precision
If optical systems are used for motion capture, then measurement precision is improved, but ease of operation deteriorates due to environmental control requirements
Solution Approach 1:
The patent replaces optical sensing that requires controlled lighting and environmental conditions with UWB radio frequency sensing. UWB tags and anchors operate independently of environmental factors such as light levels, camera visibility, and spatial constraints. This substitution allows motion capture to be performed in uncontrolled environments, significantly improving ease of operation while maintaining measurement precision through accurate time-of-flight distance measurements
3Device complexity
If UWB tags are used instead of optical systems, then device complexity is reduced, but measurement precision may deteriorate
Solution Approach 1:
The patent employs parameter changes in the UWB signal processing to achieve high measurement precision. The system uses time-of-flight measurements with sub-nanosecond resolution to calculate distances between UWB tags and anchors. By carefully controlling and measuring the propagation time of UWB signals, the system achieves centimeter-level accuracy despite using simpler radio frequency technology instead of optical systems. The parameter changes include precise timing measurements and signal processing techniques that maintain accuracy while reducing complexity
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 costs and complexity, enhances flexibility and portability, and provides accurate, real-time motion capture suitable for applications like augmented reality.
Implementation Method 1
determining distances between the anchor tag and other UWB tags
Data Source
AI summary
Ultra-wideband (UWB) tags can be used as part of a high-resolution motion capture system that may not require a cost or a complexity that is typically associated with visually based motion capture systems. The UWB based motion capture uses a bundle of UWB tags, which in a possible implementation, can be affixed to body parts of a user to sense motion of the body parts. The absolute positions of each UWB tag can then be determined by reconstructing a skeletal topology from a Euclidean distance matrix based on inter-tag ranging measurements using handshake signals of a UWB protocol.