Motion Tracking Staging System with Michelson Calibration

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Solution Overview

Problem

Existing motion tracking systems face challenges in accurately recording the relative locations of beacons attached to moving objects, particularly when large areas are involved, leading to errors in the representation of body parts and their relative positions to the environment.

Innovation Solution

A staging system with a target frame and calibration mechanisms, including a frame adjustment mechanism, mirror orientation adjustment, and a Michelson Interferometer, is used to verify the accuracy of motion tracking by comparing stage-based and motion tracking system-based beacon locations, ensuring precise alignment and calibration of the target frame mirror relative to the horizontal pivot axis.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a motion tracking system uses a large area for capturing athlete movements, then the coverage and versatility of the system is improved, but the accuracy of recording relative beacon locations deteriorates due to cumulative errors in positioning algorithms

Engineering Contradiction:
Improvecoverage areaVSAvoidbeacon location accuracy
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent introduces a staging system with a target frame and calibration spots as an intermediary reference framework between the motion tracking cameras and the athletes. This mediator provides known geometric relationships that can be used to verify and correct positioning accuracy, thereby maintaining measurement precision across large coverage areas.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces reliance on purely algorithmic positioning with an optical interferometry-based verification system. The Michelson interferometer uses light interference patterns to precisely measure the positions of calibration spots, substituting mechanical/optical measurement for computational estimation and improving accuracy.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If the motion tracking system relies on algorithmic determination of beacon locations, then the ease of operation is improved, but the reliability of location accuracy deteriorates when objects move through large spaces

Engineering Contradiction:
Improveautomatic location determinationVSAvoidlocation accuracy consistency
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent implements a feedback mechanism where the staging system with calibration spots provides reference measurements that verify the accuracy of algorithmic beacon location determination. The interferometry system continuously monitors calibration spot positions and can detect drift or errors in the motion tracking system, enabling correction and maintaining reliability.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent performs preliminary calibration by establishing known geometric relationships between calibration spots on the target frame before motion tracking begins. This pre-established reference framework allows the system to compensate for and correct positioning errors that may occur during subsequent motion tracking, improving reliability without compromising ease of operation.

Inventive Principle:
Principle #10Preliminary action

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

Enhances the accuracy of motion tracking by maintaining consistent beacon locations relative to each other and the environment, reducing errors in the representation of moving objects, particularly athletes, by providing a systematic method for calibration and verification.

Implementation Method 1

a multiple-pass interferometer having reflectors to reflect at least two beams along multiple passes through the interferometer

Methodology Applied
Scientific EffectInterference: Interference

Implementation Method 2

reflectors to reflect at least two beams along multiple passes through the interferometer

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP3863516B1Staging system to verify accuracy of a motion tracking system
Publication Date: 2025.08.20 MAGIC LEAP INC
  • EP3863516B1 patent drawingFigure 1
  • EP3863516B1 patent drawingFigure 2
  • EP3863516B1 patent drawingFigure 3~4

AI summary

A staging system has to be calibrated to determine a location of a horizontal pivot axis of a target frame. A stage calibration light beam is generated and reflected from a target frame mirror. The target frame is pivoted between first and second positions and the locations of the stage calibration light beam are detected. The locations of the stage calibration light beam provide a value representing an orientation of the target frame mirror relative to the horizontal pivot axis. The orientation of the target frame mirror is then adjusted based on the value so that the target frame mirror is more normal to the horizontal pivot axis.