Foot Sensor Gait Measurement for Lower Limb Modeling
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Solution Overview
Problem
Existing gait analysis methods require sensors to be attached to multiple positions on the legs, and the length of the lower leg must be measured in advance to estimate knee and thigh positions, limiting their applicability and accuracy.
Innovation Solution
A measurement device that detects gait events from time-series sensor data using a single sensor on the foot, employing a geometric model with constraint conditions to perform lower limb measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensors are attached to multiple positions on the legs, then measurement precision of lower limbs is improved, but device complexity and ease of operation deteriorate
Solution Approach 1:
The patent segments the measurement function by using a single sensor on the foot to capture gait events, then processing the data through geometric models with constraint conditions to derive measurements for multiple lower limb segments (thigh, shank, foot) without requiring physical sensors on each segment
Solution Approach 2:
The patent introduces geometric models with constraint conditions as intermediaries between the single foot sensor and the multiple lower limb measurements. These models act as mathematical mediators that translate foot motion data into estimates of knee, hip, and other joint positions based on anatomical constraints
2Measurement precision
If sensors are attached to multiple positions on the legs, then measurement precision of lower limbs is improved, but ease of operation deteriorates
Solution Approach 1:
The measurement system is segmented into data acquisition (single foot sensor) and data processing (geometric models with constraint conditions) components, allowing precise multi-joint measurements while simplifying the user's task to merely wearing one sensor on the foot
Solution Approach 2:
The system performs self-calibration and automatic measurement through the geometric models that use constraint conditions to derive lower limb measurements from foot sensor data without requiring manual measurement or positioning by the user
3Measurement precision
If the length of the lower leg is measured in advance, then measurement precision of knee and thigh positions is improved, but loss of time and ease of operation deteriorate
Solution Approach 1:
The patent incorporates lower leg length measurement as part of the initial calibration process that occurs automatically when the system is first set up, rather than requiring separate pre-measurement steps. The constraint conditions in the geometric models include the lower leg length as a parameter that is determined during this initial calibration and then used for all subsequent measurements
Solution Approach 2:
The system performs self-calibration by automatically determining the lower leg length and other anatomical parameters through the geometric models with constraint conditions, eliminating the need for manual pre-measurement by the user and reducing both time loss and operational complexity
Data Source
AI summary
A measurement device that includes a detection unit that detects a gait event from time-series data of sensor data related to motion of a foot, and a measurement unit that performs a measurement of lower limbs by using the sensor data for a prescribed period with a timing of the gait event as a start point, based on a geometric model on which a constraint condition related to motion of the lower limbs is imposed.