Lower Limb Prosthesis Transmission With Spring-Assisted Gait Torque

Solution Overview

Problem

Current lower limb prostheses face challenges in providing efficient energy propulsion and adapting to uneven terrains due to increased size, weight, and power requirements, limiting their suitability for pediatric patients and others who require less energy expenditure and longer battery life.

Innovation Solution

The design incorporates a main body with a foot member that rotates at a joint, featuring a transmission system with epicyclic stages and a spring mechanism that provides additional torque and energy storage, controlled by sensors and a controller to optimize gait phases and terrain adaptation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If microprocessor control and active propulsion components are added to provide more natural motion, then the motion naturalness is improved, but the size, weight, and power requirements increase

Engineering Contradiction:

Improvemotion naturalnessVSAvoidprosthesis weight

Core Design Contradiction:

Ease of operationVSWeight of moving object

Solution Approach 1:

The patent replaces the microprocessor control system with a passive mechanical system using spring elements and cam mechanisms. The spring elements store and release energy to provide active propulsion, while cams convert user's passive movements into active propulsive forces, eliminating the need for electronic controllers and reducing overall system weight.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The prosthesis is designed to utilize the user's own movement energy to power the propulsion mechanism. The spring elements are automatically compressed and released during the gait cycle, and the cam mechanisms are actuated by the user's natural foot movements, creating a self-sustaining system that requires no external power source.

Inventive Principle:

Principle #25Self-service

2Ease of operation

If microprocessor control and active propulsion components are added to provide more natural motion, then the motion naturalness is improved, but the power requirements and battery life are worsened

Engineering Contradiction:

Improvemotion naturalnessVSAvoidpower consumption

Core Design Contradiction:

Ease of operationVSUse of energy by moving object

Solution Approach 1:

The patent replaces the microprocessor control system with a passive mechanical system using spring elements and cam mechanisms. The spring elements store and release energy to provide active propulsion, while cams convert user's passive movements into active propulsive forces, eliminating the need for electronic controllers and reducing overall system weight.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The prosthesis is designed to utilize the user's own movement energy to power the propulsion mechanism. The spring elements are automatically compressed and released during the gait cycle, and the cam mechanisms are actuated by the user's natural foot movements, creating a self-sustaining system that requires no external power source.

Inventive Principle:

Principle #25Self-service

3Adaptability or versatility

If passive mechanical converting mechanism is used to convert angular change into load change, then the adaptability to uneven terrains is improved, but the device complexity increases

Engineering Contradiction:

Improveterrain adaptabilityVSAvoidmechanical mechanism complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent combines multiple functions into integrated components. The spring elements serve both as energy storage devices and as terrain adaptation mechanisms. The cam mechanisms simultaneously control the timing of spring release and the distribution of propulsive forces, reducing the number of separate components needed.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The spring-cam system is designed to perform multiple functions: energy storage, terrain adaptation, and propulsion timing control. This multi-functional design reduces overall system complexity while maintaining adaptability to various terrains and walking conditions.

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

This configuration enhances energy efficiency and adaptability, reducing the energy required for ambulation and extending battery life, making the prosthesis more suitable for a broader range of users, including pediatric patients.

Implementation Method 1

a spring mechanism that provides additional torque and energy storage

Methodology Applied

Scientific EffectElastic potential energy storage: Spring

Implementation Method 2

a transmission system with epicyclic stages

Methodology Applied

Scientific EffectMechanical advantage through gear transmission: Epicyclic Gearing

Data Source

PatentEP3265035B1Lower limb prosthesis

Publication Date: 2023.09.13 OTTOBOCK PROSTHETICS LLC

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AI summary

Powered limb prostheses with multi-stage transmissions are provided.