Capacitive Foot Presence Sensing for Automated Footwear Lacing
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Solution Overview
Problem
Existing motorized lacing systems for footwear face challenges such as high cost of manufacture, complexity, assembly difficulties, lack of serviceability, and fragile mechanical mechanisms, and premature activation issues due to improper foot detection in footwear.
Innovation Solution
A modular footwear platform with a mid-sole plate that accommodates interchangeable motorized and non-motorized lacing engines, incorporating a capacitive foot presence sensor to accurately detect foot presence and orientation, providing tactile and visual feedback, and enabling reliable, automated lacing control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If motorized lacing systems are implemented in footwear, then automated lacing function is achieved, but manufacturing cost increases
Solution Approach 1:
The lacing system is divided into independent modular components: motor unit, spool assembly with lacing string, capacitive sensor module, and control circuitry. Each module can be manufactured separately and assembled into the footwear, reducing overall manufacturing complexity and cost while maintaining automated functionality.
Solution Approach 2:
The motor unit and spool assembly are designed as universal components that can be integrated into different footwear types and styles. The standardized interface and mounting system allow the same automated lacing mechanism to serve multiple product lines, reducing per-unit manufacturing cost through economies of scale.
2Extent of automation
If motorized lacing systems are implemented in footwear, then automated lacing function is achieved, but device complexity increases
Solution Approach 1:
Multiple functions are merged into single components to reduce overall system complexity. The spool assembly integrates string storage, winding mechanism, and tensioning function. The capacitive sensor combines foot presence detection with activation triggering. The motor unit directly couples to the spool, eliminating intermediate transmission mechanisms.
Solution Approach 2:
Complex control logic is extracted from the mechanical system and implemented in software/firmware within the control circuitry. This separates the simple mechanical actuation (motor rotating spool) from the complex decision-making (when to tighten, how much tension), reducing mechanical complexity while maintaining automated functionality.
3Extent of automation
If motorized lacing systems are implemented in footwear, then automated lacing function is achieved, but assembly difficulty increases
Solution Approach 1:
The system is segmented into pre-assembled modules (motor unit with spool, sensor module, battery compartment) that can be manufactured and tested independently before final integration into footwear. This modular approach allows parallel assembly processes and reduces the skill level required for final assembly.
Solution Approach 2:
Critical sub-assemblies are pre-assembled and pre-tested before integration into the footwear. The motor unit comes pre-attached to the spool assembly with lacing string pre-threaded, and the capacitive sensor is pre-calibrated. This preliminary preparation significantly reduces on-site assembly complexity and potential errors.
4Extent of automation
If motorized lacing systems are implemented in footwear, then automated lacing function is achieved, but serviceability decreases
Solution Approach 1:
The modular architecture allows individual components (motor unit, battery, sensor) to be independently accessed and replaced. If one component fails, only that specific module needs to be serviced rather than the entire system, significantly improving serviceability while maintaining automated functionality.
Solution Approach 2:
The design allows for easy replacement of wear-prone components like the lacing string and battery as consumable parts, while the durable motor unit and control electronics can be retained and reused. This selective replacement strategy improves serviceability by focusing maintenance on specific components.
5Extent of automation
If motorized lacing systems are implemented in footwear, then automated lacing function is achieved, but mechanical reliability decreases
Solution Approach 1:
The capacitive foot presence sensor replaces mechanical switches or pressure sensors that have moving parts and contact wear. The capacitive sensing uses electrical fields to detect foot presence without physical contact, eliminating mechanical failure modes while enabling automated activation.
Solution Approach 2:
The motor shaft is directly coupled to the spool assembly, eliminating intermediate gears, belts, or linkages that could fail. This direct-drive configuration reduces the number of moving parts and potential failure points, improving mechanical reliability while maintaining the automated lacing function.
6Measurement precision
If capacitive foot presence sensor is used, then foot detection accuracy is improved, but premature activation is prevented
Solution Approach 1:
The capacitive sensor uses electrical field detection instead of mechanical pressure sensing. This allows for adjustable sensitivity thresholds and signal filtering algorithms that can distinguish between genuine foot presence (large capacitance change) and false triggers (small environmental variations), improving both detection accuracy and preventing premature activation.
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
The solution provides a robust, serviceable, and customizable footwear system with reliable automated lacing, reducing assembly complexity and ensuring proper foot detection, enhancing user experience by preventing premature activation.
Implementation Method 1
the sensor system includes a capacitive sensor configured to sense changes in a capacitance signal in response to proximity of a body
Implementation Method 2
A dielectric member can be provided between the capacitive sensor and the body to enhance an output signal from the sensor
Data Source
AI summary
A foot presence sensor system for an active article of footwear can include a sensor housing configured to be disposed at or in an insole of the article, and a controller circuit, disposed within the sensor housing, configured to trigger one or more automated functions of the footwear based on a foot presence indication. In an example, the sensor system includes a capacitive sensor configured to sense changes in a capacitance signal in response to proximity of a body. A dielectric member can be provided between the capacitive sensor and the body to enhance an output signal from the sensor.