Crutch Load Monitoring via Spring Compression and Capacitive Sensing

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Solution Overview

Problem

Existing devices for monitoring the load on a patient's leg when using crutches are either unreliable or complex in construction and expensive, with difficult assembly processes, making them unsuitable for widespread use.

Innovation Solution

A device comprising a first compression spring and a capacitive or inductive measuring device connected to the crutch's foot area, allowing for reliable load measurement and integration into standard crutches with a simple, cost-effective design that can be easily retrofitted by the patient.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If piezo sensors or load cells are used to measure force in walking aids, then measurement capability is provided, but device complexity and cost increase

Engineering Contradiction:
Improveload measurement capabilityVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex electronic sensing systems (piezo sensors, load cells) with a simple mechanical measurement system. A compression spring mechanically converts the force applied to the walking aid into a measurable displacement, which is then detected by a simple capacitive or inductive sensor. This mechanical substitution eliminates the need for complex force-sensing electronics while maintaining measurement capability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent employs inexpensive measurement components (capacitive or inductive sensors) combined with a mechanical spring system rather than expensive force sensors. This approach uses simpler, cheaper components to achieve the same measurement function, reducing overall device cost and complexity.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Measurement precision

If complex measurement devices are installed in crutches, then load monitoring is achieved, but ease of installation deteriorates

Engineering Contradiction:
Improveload monitoring capabilityVSAvoidease of installation
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent divides the measurement system into separate functional modules: a compression spring element that can be independently installed in the crutch structure, and a separate capacitive/inductive sensor component. This segmentation allows the spring mechanism to be installed mechanically without requiring integration of complex electronic systems, simplifying the installation process.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

By replacing electronic force-sensing components with a mechanical spring-displacement system, the patent enables installation using basic mechanical assembly techniques rather than requiring complex electronic integration, thereby improving ease of manufacture and installation.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If accurate force measurement is implemented, then reliability improves, but device complexity increases

Engineering Contradiction:
Improvemeasurement reliabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent achieves reliable force measurement by substituting electronic force sensors with a mechanical spring system that provides inherent mechanical linearity and stability. The spring's physical properties ensure consistent measurement behavior, while the simple capacitive or inductive detection mechanism maintains measurement reliability without adding electronic complexity.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 device provides accurate load monitoring on the patient's leg, allowing for effective relief and improved walking comfort by measuring the vertical components of reaction forces and angles, with a robust and space-saving design that does not increase the crutch's length, and can output overload signals for user adjustment.

Implementation Method 1

a first capacitive or inductive measuring device, wherein the first capacitive or inductive measuring device measures a compression of the first compression spring

Methodology Applied
Scientific EffectCapacitive sensing: Capacitance

Implementation Method 2

a first capacitive or inductive measuring device, wherein the first capacitive or inductive measuring device measures a compression of the first compression spring

Methodology Applied
Scientific EffectInductive sensing: Electromagnetic Induction

Implementation Method 3

a first compression spring connectable to a foot region of the walking support

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 4

the first capacitive or inductive measuring device measures a compression of the first compression spring when the walking support is loaded

Methodology Applied
Scientific EffectHooke's Law: Hooke's Law

Data Source

PatentEP4115868B1Device for monitoring the load of a patient's leg
Publication Date: 2024.03.06 KLAUS WURSTER GMBH
  • EP4115868B1 patent drawingFigure 1~3
  • EP4115868B1 patent drawingFigure 4~5
  • EP4115868B1 patent drawingFigure 6~8

AI summary

The invention relates to a device for monitoring the load on a patient's leg when using a walking aid, wherein the device comprises a first compression spring connectable to a foot area of ​​the walking aid and a first capacitive or inductive measuring device, wherein the first capacitive or inductive measuring device measures a compression of the first compression spring when the walking aid is loaded.