Tibial Magnetometer Gait Phase Detection
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Solution Overview
Problem
Existing gait analysis devices face challenges due to bulky and power-hungry gyroscopes, limited information from pressure-sensitive switches, high computational complexity, and sensitivity to gravity acceleration in accelerometers, as well as complex data processing requirements.
Innovation Solution
A device utilizing a three-axis magnetometer attached to a tibial segment to generate signals representative of the ambient magnetic field's projection in a sagittal plane, with signal processing to identify characteristic instants and phases of gait, including local extremes of the angle or its derivative, allowing for comfortable, low-power, and simple data processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gyroscopes are used for gait analysis, then measurement precision is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent replaces mechanical gyroscopes with a magnetometer that measures the projection of the ambient magnetic field on the tibial segment. This substitution eliminates bulky mechanical components while maintaining the ability to identify gait phases through magnetic field measurements and signal processing.
2Device complexity
If pressure sensitive switches are used, then device complexity is reduced, but information completeness deteriorates
Solution Approach 1:
The patent replaces pressure-sensitive switches with a magnetometer that provides comprehensive gait information including both stance and flight phases. The magnetometer measures magnetic field projections that reveal the complete gait cycle, eliminating the information loss inherent in pressure-switch-only systems.
3Measurement precision
If accelerometers are used for gait analysis, then measurement capability is improved, but computational complexity increases
Solution Approach 1:
The patent replaces accelerometers with a magnetometer that directly measures magnetic field projections related to gait phases. This substitution avoids the complex computational requirements of separating gravity acceleration from sensor acceleration, as the magnetometer measurements are not affected by gravitational forces.
4Ease of operation
If magnetometers are used, then ease of operation is improved, but measurement precision may deteriorate
Solution Approach 1:
The patent performs preliminary calibration to determine the orientation of the magnetometer relative to the tibial segment and the projection of the magnetic field. This preliminary action establishes reference frames and calibration parameters that enable accurate gait phase identification from subsequent magnetic field measurements, ensuring measurement precision is maintained.
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 comfortable gait analysis with minimal discomfort, providing detailed insights into gait phases and pace without the need for specific walking directions or straight-line paths, while minimizing computational complexity and power consumption.
Implementation Method 1
a magnetometer intended to be attached to a tibial segment of said person, to generate a signal representative of at least one projection in a sagittal plane of an ambient magnetic field in which it is immersed
Data Source
AI summary
The device has a three-axis magnetometer (M3) fixed at a tibial segment (ST) of a person (P) for generating a signal representing projection in a sagittal plane of an ambient magnetic field (CM) in which the person is involved. A signal processing unit (MT) i.e. desktop computer, processes the signal generated by the three-axis magnetometer to identify the instant e.g. heel-strike instant, and person walking characteristic phases.