Insole Pressure Sensing for Latency-Resistant Toe-Off Detection
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Solution Overview
Problem
Existing toe off detection methods using sensing cells are imprecise due to latency in dielectric materials, leading to time delays and requiring complex, expensive systems that can only be used in controlled environments, limiting their applicability and precision.
Innovation Solution
A method utilizing an insole with sensing cells that identifies a discharge period, collects and processes signals during this period, and triggers toe off based on predetermined thresholds to correct for latency and noise, allowing precise detection outside controlled environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensing cells with dielectric materials are used to detect toe off, then the system can measure pressure during gait, but latency in the dielectric materials causes time delay and reduces measurement precision
Solution Approach 1:
The patent applies preliminary action by identifying the discharge period (when load is decreasing) before toe off occurs and pre-calibrating threshold values during a calibration phase. This allows the system to anticipate the toe off event and prepare the detection criteria in advance, compensating for the latency-induced time delay in the sensing cell response.
Solution Approach 2:
The patent uses feedback by comparing the measured signal from sensing cells against predetermined calibration thresholds that were established during a calibration phase. The system continuously monitors the signal and triggers toe off detection when the signal falls below the threshold, creating a closed-loop feedback mechanism that compensates for latency effects.
2Measurement precision
If thousands of sensing cells and multiple sensors are combined to improve detection accuracy, then measurement precision improves, but device complexity and cost increase significantly
Solution Approach 1:
The patent merges the functions of multiple sensors into a single integrated insole system with a unified controller that manages all sensing cells. Instead of combining separate pressure sensors, camera systems, and gyroscopes as in prior art, the invention integrates all sensing functionality into the insole fabric, reducing overall system complexity while maintaining detection accuracy through signal aggregation from multiple sensing cells.
Solution Approach 2:
The insole system performs multiple functions using the same hardware components: it detects toe off, measures gait parameters, and monitors pressure distribution throughout the foot. The sensing cells and controller serve universal purposes, eliminating the need for specialized equipment for each measurement type and reducing overall device complexity.
3Measurement precision
If multiple sensors and complex systems are used for toe off detection, then measurement precision improves, but the cost and requirement for controlled laboratory environments increases
Solution Approach 1:
The insole system performs self-calibration during a calibration phase where the user wears the insole and walks naturally. The system automatically establishes threshold values based on the user's own gait characteristics without requiring laboratory equipment or technician intervention. This self-service capability enables deployment in natural environments without controlled laboratory settings.
Solution Approach 2:
The system adapts dynamically to different users and environments by establishing personalized calibration thresholds during initial use. Rather than requiring fixed laboratory conditions, the insole adjusts its detection parameters based on individual user characteristics and natural walking patterns, enabling versatile deployment in various real-world environments.
Data Source
AI summary
A method for determining toe off using a plurality of sensing cells, the method including: during the discharge period, collecting the measured signal from each sensing cell, outputting, for each sensing cell, a null output if the signal is lower than the predetermined cell calibration threshold or the measured signal if the signal is larger than or equal to a predetermined cell calibration threshold, triggering output of the toe off when the total signal is lower than a predetermined toe off threshold.