Capacitive Step Counter in Garment Fabric
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Solution Overview
Problem
Traditional step counters often inaccurately count steps due to false readings from acceleration without physical activity, and existing solutions like EMG sensors and strain gauges are uncomfortable and expensive.
Innovation Solution
A wearable step counter system integrated into garments using capacitive electrodes and microcontrollers to detect parasitic capacitive coupling between the electrodes and the wearer's legs, allowing for accurate step counting without the need for bulky sensors or complex materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional accelerometers are used for step counting, then the device can detect movement, but it produces false readings when the user experiences acceleration without physical activity (e.g., driving a car)
Solution Approach 1:
The patent replaces the traditional mechanical accelerometer-based detection system with a capacitive sensing system. The capacitive electrode detects changes in capacitance caused by the proximity and movement of the leg, rather than measuring acceleration forces directly. This substitution eliminates false readings during acceleration events like car driving, as the capacitive sensor only responds to actual leg movement relative to the electrode.
2Measurement precision
If EMG sensors are used to detect leg muscle activity, then step counting accuracy improves, but the system becomes uncomfortable and expensive due to requiring multiple skin-contact electrodes
Solution Approach 1:
The patent extracts the sensing function from the complex EMG electrode system and implements it through a simple capacitive electrode that can be integrated into the garment fabric itself. This eliminates the need for multiple skin-contact electrodes while maintaining accurate step detection through capacitance changes caused by leg proximity and movement.
Solution Approach 2:
The patent changes the detection parameter from electrical signals requiring skin contact (EMG) to capacitive coupling that occurs naturally through the garment fabric. By measuring capacitance changes between the electrode and the leg, the system achieves accurate detection without uncomfortable skin-contact electrodes.
3Measurement precision
If strain gauges are used on shoe soles to detect user weight, then step counting can be performed, but the system becomes complex and difficult to implement due to signal acquisition challenges
Solution Approach 1:
The patent replaces the mechanical strain gauge system with a capacitive sensing system. Instead of measuring physical deformation or weight directly, the capacitive electrode detects changes in capacitance caused by the proximity and movement of the leg, providing step detection information without the complexity of strain gauge signal acquisition.
4Ease of operation
If capacitive electrodes are integrated into garment fabric, then the system maintains comfort and stylish appearance, but the electrode needs to be electrically isolated from the conductive yarns
Solution Approach 1:
The patent applies local quality by creating an electrically insulating layer only at the specific location where the capacitive electrode contacts the conductive yarns in the fabric. This localized insulation prevents electrical shorting while maintaining the overall comfort and flexibility of the garment, allowing the capacitive sensing function to work effectively.
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 system provides accurate and reliable step counting while maintaining comfort and stylish appearance, capable of detecting different gait styles and independent from acceleration, making it suitable for daily use.
Implementation Method 1
The textile fabric portion is arranged on the garment for providing a parasitic capacitive coupling between the capacitive electrode and a wearer's leg
Implementation Method 2
The microcontroller is electrically connected to the capacitive electrode for evaluating the parasitic capacitive coupling so that the relative movement between the wearer's legs is detected by the microcontroller
Data Source
Figure 1
Figure 2A~2B
Figure 2C
AI summary
Disclosed is a wearable step counter system (100) comprising a garment (10) for a wearer's legs, a capacitive electrode (3) and a microcontroller (1), said garment (10) comprising a textile fabric portion (12), said capacitive electrode (3) comprising an electrically conductive yarn (22) woven into said textile fabric portion (12), said textile fabric portion (12) being arranged on said garment (10) for providing a parasitic capacitive coupling between said capacitive electrode (3) and a wearer's leg, said microcontroller (1) being electrically connected to said capacitive electrode (3) for evaluating said parasitic capacitive coupling so that the relative movement between the wearer's legs is detected by the microcontroller (1).