Magnetic Prosthetic Joint Actuator for Secure Heel Height Locking

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Solution Overview

Problem

Existing prosthetic joints lack efficient mechanisms for adjusting heel height and locking the position securely, which affects the comfort and functionality of prosthetic devices.

Innovation Solution

An actuator mechanism with a central component having magnets that attract and lock into position, allowing adjustable height adjustment and secure locking through magnetic forces, utilizing a central component with alternating polarities and markings for precise alignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a linear actuator with screws and a rotating nut is used to adjust heel height, then height adjustment is achieved, but the locking mechanism is insufficient and may allow position drift

Engineering Contradiction:
Improveposition locking reliabilityVSAvoidactuator mechanism complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the purely mechanical screw-nut locking system with a magnetic field-based locking mechanism. Magnets embedded in the rotating nut interact with corresponding magnets in the stator to create secure positional locking without relying solely on mechanical friction from screw threads. This substitution provides more reliable positioning while maintaining actuator functionality.

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

Solution Approach 2:

The patent combines the height adjustment function and position locking function into a single integrated mechanism. The rotating nut simultaneously performs both functions: it adjusts heel height through screw thread engagement while also providing secure locking through magnetic field interaction with the stator. This merging eliminates the need for separate locking mechanisms.

Inventive Principle:
Principle #5Merging (Combining)

2Stability of the object's composition

If multiple screws extend from opposite ends of the actuator, then structural stability is improved, but the manufacturing precision requirements increase

Engineering Contradiction:
Improveactuator structural stabilityVSAvoidscrew alignment precision
Core Design Contradiction:
Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The rotating nut is designed as a universal component that performs multiple functions: it engages with both screws simultaneously for structural stability, provides height adjustment through thread engagement, and enables magnetic locking through embedded magnets. This multi-functionality reduces the need for high-precision alignment of multiple screws while maintaining actuator stability.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Reliability

If an elongate magnet is coupled to the nut and surrounded by a stator with coils, then magnetic locking is achieved, but the device complexity and energy consumption increase

Engineering Contradiction:
Improvemagnetic locking reliabilityVSAvoidcoil energy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The magnetic locking system is designed to be self-sustaining through permanent magnets embedded in the rotating nut that interact with corresponding permanent magnets or magnetic elements in the stator. Once the actuator reaches the desired position, the magnetic fields automatically lock without requiring continuous energy input from coils, eliminating ongoing energy consumption for maintaining lock position.

Inventive Principle:
Principle #25Self-service

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 actuator mechanism provides secure and reproducible height adjustment, enhancing the comfort and functionality of prosthetic joints by allowing precise positioning and energy storage, mimicking natural ankle motion.

Implementation Method 1

An actuator mechanism with a central component having magnets that attract and lock into position, allowing adjustable height adjustment and secure locking through magnetic forces

Methodology Applied
Scientific EffectMagnetic force: Magnetism

Data Source

PatentEP3349697B1Magnetic locking mechanism for prosthetic or orthotic joints
Publication Date: 2025.08.06 OSSUR ICELAND EHF
  • EP3349697B1 patent drawingFigure 1
  • EP3349697B1 patent drawingFigure 2
  • EP3349697B1 patent drawingFigure 3A

AI summary

A magnetic locking actuator for a prosthetic or orthotic device is provided. The actuator includes a first component including one or more magnets and a second component including one or more magnets. The first and second components are coupled to separate portions of the device. The magnets allow for adjustment of a length of the actuator to adjust an angular orientation of the first and second portions of the device. When magnets in the second component are aligned with magnets in the first component having an opposite polarity, a position of the second component is fixed relative to the first component, locking the actuator. When magnets in the second component are not aligned with magnets in the first component having the opposite polarity, the position of the second component is adjustable relative to the first component, thereby allowing adjustment of the height of the actuator.