Inertial Sensor Joint Evaluation Apparatus for Drop Landing Analysis
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Solution Overview
Problem
Conventional methods for evaluating joint movement and assessing the risk of injury or disorder require expensive equipment like 3D motion capture systems and are limited by spatial constraints, making them unsuitable for immediate feedback and detailed evaluation of joint behavior, especially for transient movements like drop landing.
Innovation Solution
A joint evaluation apparatus using an inertial sensor unit attached near the joint to detect motion as a waveform signal, a load detection unit to capture applied loads, and a feature amount calculation unit to analyze these signals for evaluating movement quality, allowing for accurate and timely assessment of joint damage or disorder risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional evaluation methods using 3D motion capture systems are used, then measurement precision of joint angles and moments is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent replaces complex mechanical measurement systems (3D motion capture with multiple cameras and reflective markers) with inertial sensors that directly measure acceleration and angular velocity. This substitution maintains measurement precision for joint parameters while dramatically reducing system complexity and cost.
Solution Approach 2:
The patent uses inertial sensors to create a simplified measurement model that copies the essential functional capabilities of complex motion capture systems. By attaching sensors directly to body segments, it replicates the measurement of joint angles and moments without requiring the full infrastructure of optical motion capture.
2Measurement precision
If 3D motion capture systems are used, then joint movement evaluation accuracy is improved, but ease of operation deteriorates due to complex marker attachment and offline processing
Solution Approach 1:
The inertial sensor system is self-contained and requires no external infrastructure. Sensors attached to the body automatically record motion data, eliminating the need for complex marker attachment procedures and offline processing workflows required by motion capture systems.
Solution Approach 2:
The patent extracts only the essential measurement functionality from complex motion capture systems by using inertial sensors that directly measure the physical quantities of interest (acceleration, angular velocity) without requiring the full measurement infrastructure.
3Ease of operation
If inertial sensors are used to simplify measurement, then ease of operation is improved, but measurement precision deteriorates due to limited detection capability
Solution Approach 1:
The patent changes the detection parameters by using inertial sensors to directly measure acceleration and angular velocity, then derives joint parameters through mathematical relationships. This approach maintains precision by focusing on fundamental physical measurements rather than attempting to directly measure complex joint parameters.
Solution Approach 2:
The patent substitutes direct mechanical measurement of joint angles with inertial sensing of segment motion, using the known kinematic relationships between segments to calculate joint parameters. This substitution maintains accuracy while simplifying the measurement system.
4Loss of information
If conventional systems are used, then comprehensive joint evaluation is achieved, but loss of time increases due to offline processing requirements
Solution Approach 1:
The inertial sensors continuously record motion data in real-time during the activity, capturing all necessary information as it occurs. This eliminates the need for subsequent offline processing to extract evaluation data, enabling immediate feedback while preserving complete evaluation information.
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 anatomically meaningful detection and accurate forecasting of joint damage or disorder by analyzing waveform signals from inertial sensors, providing immediate feedback and detailed evaluation of joint movement quality during activities like drop landing.
Implementation Method 1
an inertia sensor attached along a joint axis detects motion of a bone along the joint axis as a waveform signal by translational acceleration or angular velocity
Data Source
AI summary
A joint evaluation apparatus includes an inertial sensor unit that is attached in a vicinity of a joint with joint axes of the joint to connect bones on both sides parallel to a detection axis and detects motion of a bone of a joint axis of which a range of motion of joint movement is limited, among the joint axes, as a waveform signal, a load detection unit that detects a load applied to the joint, a data obtaining unit that, when detecting generation of the load, obtains the waveform signal to be detected by the inertial sensor unit, in a time direction and an intensity direction, and a feature amount calculation unit that analyzes the waveform signal and calculates a feature amount that evaluates movement quality of the joint.