Finger Motion Assist Device With Constant-Distance Arm Pivot

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Solution Overview

Problem

Conventional wearable motion assistive devices for fingers are bulky and heavy, imposing a significant burden on users.

Innovation Solution

A motion assistive device with a simplified mechanism that includes at least one arm pivotably supported by an arm supporting mechanism, connected to the finger via a connective member, and driven by an arm driving means, allowing the arm to pivot while maintaining a constant distance from its pivot center, thus reducing complexity and weight.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a pivoting mechanism is provided for each joint of each finger, then finger joint movement can be assisted, but the device becomes large and heavy

Engineering Contradiction:
Improvefinger joint movement assistanceVSAvoiddevice weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The patent merges multiple pivoting mechanisms into a single integrated mechanism. Instead of providing separate actuators and pivoting mechanisms for each finger joint (MP joint, PIP joint, DIP joint), the invention uses one pivoting mechanism that simultaneously assists all three joints through a connected link structure. This consolidation dramatically reduces device weight while maintaining the ability to assist finger joint movement.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The single pivoting mechanism is designed to perform multiple functions by assisting movement at multiple joints (MP, PIP, and DIP joints) simultaneously. The connected links transmit the driving force from one pivoting mechanism to multiple finger joints, making the mechanism universal in its application across different joints rather than dedicated to a single joint.

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

2Reliability

If a pivoting mechanism is provided for each joint of each finger, then finger joint movement can be assisted, but the device complexity increases

Engineering Contradiction:
Improvefinger joint movement assistanceVSAvoidmechanism complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges multiple pivoting mechanisms into a single integrated mechanism. Instead of providing separate actuators and pivoting mechanisms for each finger joint (MP joint, PIP joint, DIP joint), the invention uses one pivoting mechanism that simultaneously assists all three joints through a connected link structure. This consolidation dramatically reduces device weight while maintaining the ability to assist finger joint movement.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The single pivoting mechanism is designed to perform multiple functions by assisting movement at multiple joints (MP, PIP, and DIP joints) simultaneously. The connected links transmit the driving force from one pivoting mechanism to multiple finger joints, making the mechanism universal in its application across different joints rather than dedicated to a single joint.

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

Data Source

PatentEP4101435B1Motion assist device
Publication Date: 2025.09.17 FRONTACT LTD
  • EP4101435B1 patent drawingFigure 1A
  • EP4101435B1 patent drawingFigure 1B
  • EP4101435B1 patent drawingFigure 1C(a)~1C(b)

AI summary

This motion assist device 100 assists with flexing and extending of fingers F1, F2 of a user, the motion assist device 100 comprising: at least one arm 10; at least one connection member 20 configured so as to be capable of connecting the at least on arm 10 to each of the fingers F1, F2; an arm support mechanism 30 that turnably supports the at least one arm 10, the arm support mechanism 30 being configured so as to be mountable on the back Hb of the hand H of the user; an arm drive means 40 that causes the at least one arm 10 to turn; and a stopper 50 that extends from the arm support mechanism 30, the stopper 50 being configured so as to restrict movement of the proximal phalanges of the fingers of the user by being in contact with the proximal phalanges. The at least one arm 10 is configured so as to turn while the distance Dr between the at least one connection member 20 and the turning center Cr of the at least one arm 10 is kept fixed.