Portable Load Cell for Weight Stack Strength Testing

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Solution Overview

Problem

Current methods for measuring muscle strength in clinical and fitness settings lack reliability and accuracy, particularly for patients in rehabilitation or with chronic conditions, as they rely on subjective manual tests or expensive isokinetic dynamometers, which are not portable or practical for widespread use.

Innovation Solution

A portable, adaptable isometric strength testing device that mounts to a weight stack, featuring a load cell and modular design with adjustable components, allowing for accurate force measurement and data recording via a connected electronic device, ensuring hands-free operation and compatibility with various exercise equipment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If manual muscle testing is used for strength assessment, then the testing process is fast and simple, but the reliability and accuracy of measurement deteriorates

Engineering Contradiction:

Improvetesting process simplicityVSAvoidstrength measurement accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent introduces a load cell as an intermediary device between the patient and the measurement system. The load cell objectively measures force applied during exercise, eliminating the subjectivity inherent in manual muscle testing while maintaining ease of operation through simple integration with existing exercise equipment.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the mechanical/manual assessment system with an electronic sensing system. Instead of relying on clinician judgment and manual resistance application, the load cell electronically measures force, providing objective and repeatable data while keeping the overall system simple to operate.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If isokinetic dynamometers are used for strength testing, then measurement accuracy is improved, but device cost and portability deteriorate

Engineering Contradiction:

Improvestrength testing accuracyVSAvoidequipment cost and portability

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts the essential measurement function (force sensing) from the complex isokinetic dynamometer system. By using only a load cell to measure force while allowing natural movement, the invention eliminates the need for expensive, complex isokinetic machinery while retaining accurate strength measurement capability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent employs inexpensive load cells instead of expensive isokinetic dynamometers. The load cells provide sufficient measurement accuracy for clinical purposes at a fraction of the cost, making the system economically viable for widespread use in various healthcare settings.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Loss of time

If hand held dynamometers are used for strength assessment, then setup time is reduced, but measurement reliability deteriorates due to clinician positioning and resistance application

Engineering Contradiction:

Improvesetup timeVSAvoidmeasurement consistency

Core Design Contradiction:

Loss of timeVSReliability

Solution Approach 1:

The patent enables the measurement system to serve itself by having the patient perform natural exercises while the load cell automatically records force data. This eliminates the need for clinician positioning and manual resistance application, ensuring consistent and reliable measurements without increasing setup time.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

Instead of the clinician applying resistance to the patient (traditional approach), the patent inverts the system by having the patient apply force to the exercise equipment while the load cell measures the resulting force. This reversal eliminates clinician variability and improves measurement reliability.

Inventive Principle:

Principle #13The other way round (Inversion)

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

Provides a reliable, valid, and objective measurement of muscle strength, reducing user variability and equipment costs, while being easily transportable and suitable for diverse clinical and fitness applications, such as post-surgical rehabilitation and chronic condition management.

Implementation Method 1

The sensor is adapted and configured to measure a force applied to the pin when the pin is inserted into the hole and a subject exerts force to the weight stack machine

Methodology Applied

Scientific EffectLoad cell force measurement: Force

Data Source

PatentUS11099089B2Portable load testing device

Publication Date: 2021.08.24 GOODSTADT NOEL M

AI summary

In described embodiments, a strength testing device that can be applied to a weight stack is provided. The strength testing device can be used in physical therapy, chiropractics, or other rehabilitation professionals to assess the strength of a patient. The strength testing device can also be used in the fitness industry by strength coaches and personal trainers.