Capacitor Sensor Array for 3D Force Detection in Athletic Footwear
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Solution Overview
Problem
Existing foot force monitoring systems are bulky, prone to quick sensor failure under high impact, require frequent battery charging, provide only Z force information, have low sampling rates, and are not suitable for use during games or practices, limiting their effectiveness for elite athletes.
Innovation Solution
A capacitor-based sensor array integrated into shoes that provides X, Y, and Z force data with high sampling rates, is ultra-low power, and durable enough for extended use, allowing for accurate direction and magnitude analysis of ground reaction force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a foot force monitoring system is designed to be portable and wearable, then it enables monitoring during athletic activities, but it becomes bulky and requires frequent battery charging
Solution Approach 1:
The system uses periodic wireless power transfer through the sole of the shoe, charging the battery during normal athletic activities rather than requiring separate charging sessions. The power transmission occurs in periodic bursts as the athlete moves, converting mechanical motion into electrical energy continuously during use.
Solution Approach 2:
The system harvests energy from the athlete's own movements during athletic activities to charge the battery, making the device self-sustaining during normal operation. The foot force monitoring system converts the mechanical energy of running or walking into electrical energy to power itself.
2Measurement precision
If pressure sensors are placed directly on the insole for accurate force detection, then measurement precision improves, but sensor failure rate increases under high impact
Solution Approach 1:
The system uses a nested structure where an outer compression plate is placed within an inner compression plate, creating a protective enclosure for the pressure sensors. This nested arrangement allows the outer plate to absorb and distribute impact forces, protecting the inner sensors from direct high-impact contact while maintaining measurement accuracy.
Solution Approach 2:
The compression plates are positioned between the foot and the pressure sensors to provide beforehand cushioning against impact forces. This protective layer absorbs shock before it reaches the sensors, preventing damage while allowing accurate force measurement during athletic activities.
3Measurement precision
If multiple layers of pressure sensors are used to capture detailed force data, then measurement precision improves, but device complexity increases
Solution Approach 1:
The system transitions from using multiple stacked layers of sensors in the vertical dimension to using a single layer of sensors with multiple compression plates in the horizontal dimension. This dimensional change allows detailed force measurement across different areas of the foot without increasing vertical complexity or requiring multiple sensor layers.
Solution Approach 2:
The system divides the force detection function into multiple compression plates positioned at different locations, each with its own pressure sensor. This segmentation allows detailed force data collection across the foot surface while keeping each sensor unit simple and the overall structure manageable.
4Measurement precision
If high sampling rates are implemented for accurate force analysis, then measurement precision improves, but power consumption increases
Solution Approach 1:
The system maintains continuous high-rate sampling of force data during athletic activities without interruption, enabled by the continuous wireless power transfer. The periodic power bursts occur frequently enough to support high sampling rates while the system remains powered throughout the entire activity duration.
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 reliable, high-frequency data collection during athletic activities, improving power and consistency by providing detailed ground reaction force data, suitable for both training and competition.
Implementation Method 1
A capacitor-based sensor array integrated into shoes that provides X, Y, and Z force data with high sampling rates
Data Source
AI summary
A force detection system includes first and second sets of pressure sensors, memory, and a processing module. The first set of pressure sensors are in an insole of a shoe and the second set of pressure sensors are in an outsole of a shoe. The processing module receives first data regarding the first set of pressure sensors and generates a first digital representation of the first data. The processing module also receives second data regarding the second set of pressure sensors and generates a second digital representation of the second data. The processing module also writes the first and second digital representations to the memory.