Over-Shoe Contact Sensor for Gait Measurement

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Solution Overview

Problem

Existing gait tracking methods are costly, bulky, and lack open architecture, making them unsuitable for integration with custom robotic rehabilitation hardware and software, and they often fail to accurately measure under-the-foot forces essential for detecting gait abnormalities.

Innovation Solution

An over-shoe contact sensor with five metal sheets and conductive rubber pads is used to detect gait events and measure under-the-foot forces. The sensor is compact, durable, and encased in a rubber shell, allowing for accurate force distribution analysis and integration into custom rehabilitation systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If external instrumentation such as anchored infrared-based motion capture systems or portable inertial measurement units are used, then gait tracking information can be obtained, but the cost becomes prohibitively high and the physical footprint becomes large

Engineering Contradiction:

Improvegait tracking accuracyVSAvoidsystem size and cost

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex optical/mechanical gait tracking systems with a simple electrical contact sensing system. Instead of using infrared cameras or IMUs, the invention uses conductive rubber pads that create electrical circuits when compressed by foot contact, providing gait event detection through basic electrical measurements rather than complex mechanical or optical systems

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent employs inexpensive conductive rubber pads as the sensing element. These simple, low-cost components can be easily replaced or reconfigured, eliminating the need for expensive proprietary hardware while providing sufficient functionality for gait analysis in rehabilitation settings

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Ease of operation

If insole pressure sensors are used, then some gait information can be provided, but the ability to accurately measure under-the-foot forces is lacking

Engineering Contradiction:

Improvesensor placement convenienceVSAvoidunder-the-foot force measurement accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

Instead of placing sensors inside the shoe (insole), the patent inverts the approach by placing the contact sensors on the bottom surface of the shoe. This external placement allows direct measurement of forces applied to the shoe sole, providing accurate under-the-foot force data while maintaining ease of operation through simple attachment to the shoe exterior

Inventive Principle:

Principle #13The other way round (Inversion)

3Reliability

If existing gait tracking systems are used, then gait events can be detected, but reliable integration with custom robotic rehabilitation hardware and software is precluded

Engineering Contradiction:

Improvegait event detection reliabilityVSAvoidintegration flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent creates a universal sensing interface using standard electrical components (conductive rubber pads, foil sheets, breadboards) that can be integrated with any custom robotic rehabilitation system. The system provides multiple functions including force measurement, gait event detection, and open architecture integration, making it adaptable to various research and clinical applications rather than being locked into proprietary systems

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 over-shoe contact sensor provides reliable and accurate timing of gait events and force distribution, overcoming the limitations of existing methods by being cost-effective, compact, and durable, thus enabling effective integration into robotic rehabilitation systems.

Implementation Method 1

Each conductive rubber pad functions as a pressure-sensitive resistor, with its resistance decreasing as the pressure on it increases

Methodology Applied

Scientific EffectPiezoresistive effect: Piezoresistive Effect

Implementation Method 2

When the sensor is compressed, the foil sheets move towards each other until they contact the conductive rubber, creating an electrical short that is measured to determine if the sensor is compressed in that given area

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS20250169756A1Over-Shoe Contact Sensor for Gait Measurement in Physical Therapy

Publication Date: 2025.05.29 NEXTSTEP ROBOTICS INC

AI summary

An over-shoe contact sensor device enabling a novel method and a portable embodiment for reliably and accurately detecting multiple gait events with several key attributes particularly advantageous in physical therapy applications such as compact size, quick donning and doffing, and durability to wear and tear. The device is a cost-effective alternative to existing anchored motion tracking systems when utilized for the same purpose. The device comprises a plurality of sensors for measuring gait events and under-the-foot forces and processing data collected from the sensors to provide a useful output for physical therapists and the like to determine the gait of the wearer.