Wearable Gait Start Detection via Center of Pressure Shift
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Solution Overview
Problem
Current gait start intention detection systems for individuals with impaired mobility are inefficient in pre-detecting the intention to walk, as they only detect the intention when the walker has already started moving, resulting in delayed detection.
Innovation Solution
A gait start intention detection device utilizing multiple sensors on the soles of both feet to measure ground reaction forces, calculate the center of pressure (COP) location, and identify the gait phase, allowing for real-time detection of the intention to walk by analyzing the increase in ground reaction force of the swing foot heel and movement of the COP to the rear side.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ground reaction force magnitude peak detection is used to detect gait start intention, then detection can be achieved when walker moves to some extent, but detection time is delayed and cannot detect intention early enough
Solution Approach 1:
The patent applies preliminary action by detecting anticipatory postural adjustments (APAs) that occur before the actual gait initiation. The sensor array detects subtle weight shifts and center of pressure changes that precede voluntary movement, allowing the system to predict gait start intention before the walker actually moves, thus providing earlier detection without sacrificing accuracy
Solution Approach 2:
The patent segments the foot sole into multiple sensor units arranged in a grid pattern, allowing detection of localized pressure changes. This segmentation enables the system to detect subtle APAs at specific foot regions (heel, midfoot, forefoot) independently, improving early detection capability by identifying preliminary weight shift patterns that indicate impending gait initiation
2Measurement precision
If multiple sensor units are deployed on foot soles to improve detection accuracy, then gait start intention can be detected earlier with higher precision, but device complexity increases
Solution Approach 1:
The patent makes the sensor array multi-functional by using the same pressure-sensitive sensor grid for multiple purposes: detecting gait start intention, tracking center of pressure trajectory, analyzing weight distribution patterns, and identifying different phases of gait initiation. This universality reduces overall system complexity by consolidating multiple detection functions into a single sensor array rather than requiring separate sensors for each function
Solution Approach 2:
The sensor array performs self-service by automatically processing raw pressure data through embedded algorithms that calculate center of pressure, detect weight shift patterns, and identify gait initiation events without requiring external complex processing systems. The system uses its own sensor data to trigger detection events and provide feedback, reducing the need for additional control hardware
3Measurement precision
If force plate or force sensing resistor sensors are used to detect ground reaction force, then gait start intention can be detected, but the system is not wearable and lacks ease-of-wear
Solution Approach 1:
The patent uses flexible pressure-sensitive sensors embedded in an insole configuration, allowing the measurement system to conform to the foot's anatomy and be worn during normal activities. This flexible film-based sensor array maintains measurement accuracy while enabling wearability, unlike rigid force plates. The thin-film sensors capture ground reaction forces through the insole without interfering with natural foot movement or comfort
Solution Approach 2:
The patent replaces the traditional mechanical force plate system with a lightweight electronic sensor array integrated into a wearable insole. This substitution transitions from a bulky, stationary mechanical measurement platform to a compact, flexible electronic system that can be worn on the foot, maintaining measurement capability while dramatically improving portability and ease of wear
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 early detection of gait start intention, providing sufficient lead time to control gait assistive devices, with high consistency and accuracy, improving the efficiency of gait assistive technologies.
Implementation Method 1
a plurality of left foot sole sensor units to measure a left ground reaction force signal generated from a left foot sole while walking, a plurality of right foot sole sensor units to measure a right ground reaction force signal generated from a right foot sole while walking
Data Source
AI summary
Disclosed is a gait start intention detection device for detecting a walker's gait start intention, including a plurality of left foot sole sensor units and a plurality of right foot sole sensor units to measure ground reaction force signals generated from foot soles while walking, and a calculation unit to receive and calculate the left ground reaction force signal and the right ground reaction force signal, wherein the calculation unit calculates a center of pressure (COP) location in a walking direction and a direction perpendicular to the walking direction using data of the ground reaction force signal measured from each sensor unit, and detects the walkers gait start intention when a ground reaction force of a swing foot heel of the walker increases, and at the same time, the COP location moves to a rear side of the walker.