Motion Analysis Device Using Muscle Synergy and Equilibrium Point Calculation
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Solution Overview
Problem
Existing motion analyzing methods for human motion control are limited by the need for maximum voluntary contraction (MVC) measurements, which can be burdensome for elderly or patients and have practical limitations in rehabilitation, and do not accurately generalize biological motions due to simplified models.
Innovation Solution
A motion analyzing device and method that detects myogenic potentials and limb endpoint positions using a musculoskeletal model, calculating equilibrium points and muscle synergies without requiring MVC measurements, by employing a processor to calculate agonist-antagonist muscle co-activation ratios and muscle synergies based on detected myogenic potentials and limb positions, ensuring the endpoint position matches the equilibrium point in a static posture under gravity compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If maximum voluntary contraction (MVC) measurements are used to analyze muscle activity, then the motion analysis can be performed, but the measurement becomes burdensome for elderly or patients and reduces ease of operation
Solution Approach 1:
The invention extracts and eliminates the MVC measurement step from the motion analysis process. By using EMG signals during natural voluntary movements instead of requiring separate MVC measurements, the method removes the burdensome maximum effort requirement while maintaining the ability to calculate muscle activity and analyze motion patterns.
Solution Approach 2:
The system uses EMG signals naturally present during voluntary movement to automatically determine muscle activation levels. The muscle activity information is obtained self-service style from the subject's normal movement without requiring additional maximum effort maneuvers, making the measurement process easier and more suitable for elderly or patients.
2Productivity
If simplified models with assumptions about muscle size, moment arm, and MVC values are used, then the motion analysis can be performed, but the analysis accuracy deteriorates for generalizing biological motions
Solution Approach 1:
The invention changes the input parameters from assumed MVC values and simplified geometric parameters to actual EMG signal measurements during voluntary movement. By using measured EMG data and individualized musculoskeletal parameters, the system maintains computational efficiency while significantly improving the accuracy and generalizability of motion analysis results.
3Loss of information
If MVC measurements are required for motion analysis, then muscle activity can be quantified, but the measurement burden increases and practical applicability in rehabilitation decreases
Solution Approach 1:
The invention extracts muscle activity information directly from EMG signals during natural movement, eliminating the need for separate MVC measurement procedures. This extraction approach preserves all necessary muscle activity data while removing the practical burdens of maximum effort testing.
Solution Approach 2:
The EMG signal serves as an intermediary that provides muscle activity information without requiring direct MVC measurement. The EMG signals act as a mediator between the subject's natural movement and the quantification of muscle activation levels, enabling practical application in rehabilitation settings.
Data Source
AI summary
A motion analyzing device includes a myogenic potential measuring unit (20) and a myogenic potential measurement processor (101) to measure the muscle activity of a person who performs a motion and a motion measuring unit (30) and a position measurement processor (102) to measure the body motion. The motion analyzing device also includes an AA muscle co-activation ratio calculating unit (103), a muscle synergy calculating unit (104) and an equilibrium point calculating unit (105) to calculate an equilibrium point of the person and a muscle synergy that is a set of base vectors describing the equilibrium point based on a musculoskeletal model of the person and a constraint condition that the position of the endpoint of the limb matches the position of the equilibrium point in a static situation to keep a posture still under gravity compensation.