Foot-Mounted Acceleration Sensor for Heel Strike Detection
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Solution Overview
Problem
Existing methods for detecting gait events, such as heel strike, are limited by the requirement for specific sensors to be attached to specific body parts, and they may not function accurately at lower sensor frequency settings.
Innovation Solution
A detection device that acquires data including dorsiflexion peak time, plantarflexion peak time, and travel direction acceleration from sensor data on a foot movement, and uses this data to detect a candidate time for heel strike by identifying a feature signal point in the travel direction acceleration within a specified investigation time period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pressure sensor is installed inside a shoe to analyze gait state, then gait analysis is enabled, but the device becomes complex and requires precise sensor placement
Solution Approach 1:
The patent extracts the gait detection function from complex pressure sensor systems and implements it using simple acceleration sensors that measure heel strike events. This eliminates the need for complex pressure mapping systems while maintaining gait analysis capability through a simpler sensor-based approach.
Solution Approach 2:
The patent replaces mechanical pressure sensing systems with inertial measurement systems using acceleration sensors. This substitution allows gait detection without requiring complex pressure sensor installations, using instead the acceleration data from heel strikes to identify gait events.
2Reliability
If an acceleration sensor is attached to an ankle to analyze gait state, then gait analysis is enabled, but the device becomes complex and requires precise sensor placement
Solution Approach 1:
The patent extracts the gait detection function from complex multi-sensor systems and implements it using simple acceleration sensors placed on the foot. This eliminates the need for complex sensor assemblies while maintaining gait analysis capability through focused measurement of heel strike events.
3Reliability
If a smartphone is attached to a body trunk and a pressure sensor to a sole of foot to analyze gait state, then gait analysis is enabled, but the device becomes complex and requires precise sensor placement
Solution Approach 1:
The patent extracts the gait detection function from complex multi-device systems and implements it using a single acceleration sensor on the foot. This eliminates the need for both smartphone and pressure sensor combinations, simplifying the system while maintaining gait analysis capability through direct acceleration measurement.
4Reliability
If the operation frequency of the acceleration sensor is 100 Hz or more, then heel strike event detection is enabled, but the device cannot function at lower frequencies
Solution Approach 1:
The patent changes the detection parameter from high-frequency acceleration peaks to low-frequency gravitational acceleration changes. This parameter transformation enables heel strike detection at lower sensor frequencies (below 100 Hz) by measuring the characteristic acceleration pattern rather than relying on high-frequency sampling.
Data Source
AI summary
A detection device that includes an acquisition unit that acquires data including a dorsiflexion peak time, a plantarflexion peak time, and travel direction acceleration acquired from sensor data regarding a movement of a foot, a candidate detection unit that detects, as a candidate time for heel strike, a time of a feature signal point extracted from time-series data of the travel direction acceleration in an investigation time period starting from an acceleration peak time detected from the travel direction acceleration based on the dorsiflexion peak time, and an output unit that outputs the detected candidate time as a heel strike time.