Force Sensor Data Analysis Using Inflection Point Detection
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Solution Overview
Problem
Existing systems for analyzing force sensor data from underfoot sensors face challenges in accurately detecting foot contact events and ground reaction forces, especially in real-world settings outside laboratory conditions, due to the need for precise threshold crossing methods and costly equipment.
Innovation Solution
The system analyzes force sensor data by identifying inflection points to detect foot contact events, allowing for more sensitive detection of foot contact and foot off, even at different force signal heights, and uses inertial measurement unit (IMU) data to adjust ground reaction force signals for improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If threshold crossing methods are used to detect foot contact events, then detection can be performed with simple equipment, but detection accuracy deteriorates in real-world settings outside laboratory conditions
Solution Approach 1:
The patent transforms the detection approach by changing from threshold-based detection to inflection point detection based on signal derivatives. This parameter change in the detection method allows accurate foot contact event identification in real-world settings while maintaining compatibility with simple wearable force sensor equipment
Solution Approach 2:
The patent replaces the mechanical threshold crossing method with a mathematical approach using signal differentiation and inflection point detection. This substitution enables more accurate detection of foot contact events by identifying changes in the rate of force signal change rather than relying on fixed thresholds
2Measurement precision
If inflection point detection is used to identify foot contact events, then detection sensitivity improves, but signal processing complexity increases
Solution Approach 1:
The patent applies preliminary filtering and preprocessing to the force sensor signals before performing inflection point detection. This preliminary action reduces noise and prepares the signal, making the subsequent derivative calculation and inflection point identification more reliable while managing processing complexity
3Measurement precision
If force sensor data is analyzed to determine ground reaction forces, then accurate biomechanical data can be obtained, but costly laboratory equipment is required
Solution Approach 1:
The patent creates a computational model that replicates the function of expensive laboratory force plates using inexpensive wearable force sensors. By processing signals from multiple low-cost sensors and applying signal differentiation techniques, the system copies the ground reaction force measurement capability of laboratory equipment at a fraction of the cost
Solution Approach 2:
The patent makes the wearable force sensor system multi-functional by enabling it to perform both foot contact event detection and ground reaction force determination. This universal approach allows a single inexpensive wearable device to replace multiple specialized laboratory instruments
Data Source
AI summary
A system, method, and computer program product for analyzing force sensor data is provided. Force sensor data collected from a plurality of force sensors positioned underfoot is analyzed to detect foot contact events and/or a foot contact period. Foot contact and/or foot off can be detected based on inflection points identified in the force signal data received from the plurality of sensors. Identifying foot contact events by detecting inflection points in the force sensor data can increase the sensitivity of detecting both foot contact and foot off. The use of inflection points also allows both foot contact and foot off to be identified even when these foot contact events occur at different force signal heights. Methods for determining ground reaction force data and correcting the magnitude of ground reaction force signals are also provided.