Magnetic Overload Coupling for Prosthetic Hand Position Locking

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Solution Overview

Problem

Orthopedic devices, such as prosthetic hands, face challenges in maintaining the position of end effectors without damage from external torques, which can lead to damage of the locking mechanism and other components, especially when external forces exceed the threshold, potentially rendering emergency opening mechanisms inoperable.

Innovation Solution

Incorporating an overload protection system with magnetically coupled coupling elements that allow torque transmission only up to a limit torque, preventing damage by decoupling and absorbing excessive external torques, and utilizing a locking device to maintain the end effector's position without external movement unless the limit torque is exceeded.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a locking mechanism is used to maintain the end effector's position, then the position stability is improved, but the risk of damage from external torques increases

Engineering Contradiction:
Improveposition stabilityVSAvoiddamage risk from external torques
Core Design Contradiction:
Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a magnetic coupling system as an intermediary between the drive device and end effector. The magnetic coupling transmits torque up to a threshold while allowing slip when the threshold is exceeded, protecting the locking mechanism from damage while maintaining position stability under normal operating conditions.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The magnetic coupling elements are designed to absorb and dissipate excessive external torques before they can reach the locking mechanism. This beforehand cushioning prevents damage by allowing controlled slip when torques exceed the magnetic coupling's holding force, protecting the locking mechanism from harmful forces.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

2Stability of the object's composition

If the locking mechanism blocks all external forces, then the position maintenance is improved, but the emergency opening capability is compromised

Engineering Contradiction:
Improveposition maintenanceVSAvoidemergency opening capability
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The magnetic coupling provides dynamic torque transmission - it maintains a firm connection under normal operating torques to ensure position maintenance, but automatically slips when excessive forces are applied. This dynamic behavior allows the system to maintain position while still permitting emergency opening when necessary forces are applied.

Inventive Principle:
Principle #15Dynamics

3Power

If the magnetic coupling elements are strongly coupled, then the torque transmission efficiency is improved, but the overload protection capability is reduced

Engineering Contradiction:
Improvetorque transmission efficiencyVSAvoidoverload protection capability
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The magnetic coupling strength is carefully calibrated to operate at specific torque thresholds. By adjusting magnetic field strength and coupling geometry, the system achieves optimal torque transmission efficiency for normal operations while maintaining the ability to slip at predetermined overload thresholds, balancing both torque transmission and protection capabilities.

Inventive Principle:
Principle #35Parameter changes

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 overload protection system effectively prevents damage to the orthopedic device components by allowing controlled movement in one direction due to external forces, ensuring the locking mechanism is not damaged and maintaining the end effector's position within safe torque limits, thus extending the device's functionality and reducing repair costs.

Implementation Method 1

the overload protection device has at least a first coupling element and a second coupling element which are rotatable relative to one another and magnetically coupled

Methodology Applied
Scientific EffectMagnetic coupling: Magnetism

Data Source

PatentEP3678606B1Orthopedic device with overoad protection
Publication Date: 2024.01.10 OTTO BOCK HEALTHCARE PROD GMBH
  • EP3678606B1 patent drawingFigure 1
  • EP3678606B1 patent drawingFigure 2
  • EP3678606B1 patent drawingFigure 3

AI summary

The invention relates to an orthopedic device comprising an end effector (8) and a drive device (2) which is designed to drive the end effector (8) by transmitting a torque from the drive device (2) to the end effector (8). The invention is characterized in that the orthopedic device has an overload protection (4) which is designed to prevent the transmission of a torque from the end effector (8) to the drive device (2) only up to a threshold torque in at least one direction, wherein the overload protection (4) has at least one first coupling element (12) and a second coupling element (14) which can be rotated relative to each other and which are magnetically coupled.