Hand Exoskeleton Three-Layer Sliding Spring Mechanism

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Solution Overview

Problem

Conventional hand exoskeleton devices face challenges in being small and light while maintaining sufficient power for supporting finger motions, with existing mechanisms like link, wire, and fluid drive systems either increasing size, being complex, or requiring additional actuators.

Innovation Solution

A three-layered sliding spring mechanism is used, where zeroth, first, and second outer mounting parts are connected by upper and lower springs, with a drive spring capable of sliding longitudinally, allowing for adjustable torque application to finger joints, enabling natural flexion and extension movements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If a link drive mechanism is used to transmit finger motions, then sufficient power for supporting motions can be generated, but the device size increases and mechanical play occurs

Engineering Contradiction:
Improveoutput powerVSAvoiddevice size
Core Design Contradiction:
PowerVSVolume of moving object

Solution Approach 1:

The device is divided into multiple link members (first link member, second link member, third link member) that can independently move relative to each other. Each link member is connected through joints that allow relative motion, enabling the transmission of finger motions while maintaining a compact overall structure. The segmentation allows power transmission through multiple small components rather than one large component.

Inventive Principle:
Principle #1Segmentation

2Volume of moving object

If a wire drive mechanism is used to drive joints, then the transmission route can be reduced in size, but the power part mechanism becomes complicated and the wire extends and shrinks

Engineering Contradiction:
Improvetransmission route sizeVSAvoidpower part mechanism complexity
Core Design Contradiction:
Volume of moving objectVSDevice complexity

Solution Approach 1:

The patent replaces the wire drive mechanism with a direct mechanical link drive system. Instead of using wires that extend and shrink, the invention uses rigid link members connected by joints that directly transmit motion. This substitution eliminates the complexity of power transmission mechanisms while maintaining a compact size, as the link members form a straightforward mechanical chain from the finger tip to the base.

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

3Weight of moving object

If a three-layered connecting sliding spring mechanism is used, then the device can be made small and light, but the structure becomes complicated with multiple movable parts

Engineering Contradiction:
Improvedevice weightVSAvoidstructure complexity
Core Design Contradiction:
Weight of moving objectVSDevice complexity

Solution Approach 1:

The patent merges multiple functions into the link members and joints. Each link member serves both as a structural component and as a power transmission element. The joints serve both to connect link members and to enable relative motion. This merging reduces the number of separate movable parts compared to a three-layered sliding spring mechanism, simplifying the overall structure while maintaining light weight and compact size.

Inventive Principle:
Principle #5Merging (Combining)

4Power

If the link drive mechanism is used, then relatively large output can be achieved, but the device is likely increased in size

Engineering Contradiction:
Improveoutput powerVSAvoiddevice length
Core Design Contradiction:
PowerVSLength of moving object

Solution Approach 1:

The link members are designed to nest within each other when the finger is in a flexed position. The first link member can be positioned within the second link member, and the second within the third, creating a compact nested structure. This nesting allows the device to achieve relatively large output power through the link mechanism while minimizing the extended length when not in use, solving the contradiction between power output and device length.

Inventive Principle:
Principle #7Nested doll (Nesting)

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 device is compact, lightweight, and capable of transmitting significant power, supporting natural gripping motions with a single drive mechanism, while reducing the number of parts and simplifying the structure, making it safe and efficient for rehabilitation and daily activities.

Implementation Method 1

upper springs and lower springs arranged in parallel... each upper spring comprising fixed ends for engaging sliding mechanisms... the lower springs for fixing lower portions of the respective outer mounting parts are fixed at both ends to the respective outer mounting parts

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP2954988B1Hand exoskeleton device
Publication Date: 2020.05.06 KYUSHU UNIV
  • EP2954988B1 patent drawingFigure 1~2
  • EP2954988B1 patent drawingFigure 3~4
  • EP2954988B1 patent drawingFigure 5

AI summary

Provided is a hand exoskeleton device that is compact, lightweight, is worn at the fingers of a human body, and is capable of assisting in activities of daily living. The hand exoskeleton device performs motion conversion by means of a single drive means by means of a three-layer sliding spring mechanism, thereby transmitting motive force with respect to the metacarpophalangeal joints, the proximal interphalangeal joints, and the distal interphalangeal joints of the fingers of a human, thus being able to assist in activities of daily living. By means of the hand exoskeleton device, it is possible to achieve a device that supports the grasping action of the fingers of a human body in a manner that is more lightweight and compact than has been conventional. The hand exoskeleton device is characterized by being able to transmit a large driving force and being able to drive the flexion and extension of the three joints of the fingers by means of a single drive means. Furthermore, the device main body has flexibility, and so driving is possible in a safe manner.