Research and development of decorative electric prosthetic hand

Akira Otsuka

Prefectural University of Hiroshima Faculty of Health and Welfare Department of Physical Therapy

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RPR

Outline

1. Background
2. Purpose of research and development
3. Examination of the mechanism of the prosthesis
4. Simulation
5. Four types of constraints
6. Analysis result
7. Consideration
8. Summary

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Background

69 out of 403 people (17%) are using two or more types of prosthetic hand, such as decorative prostheses and electric prostheses.

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Decorative prostheses

Electric prostheses

Active prostheses

Background

• The number of users of decorative prostheses was 334 (80%)

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• The number of active prostheses was 86 (21%)

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• The number of electric prostheses was 6 (1%)

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(There are duplicate answers)

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Background

There are some parts that are visually and functionally unsatisfactory with respect to the active prosthesis

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If these improvements make the active technique easier to use, it is thought that the number of people using the active prosthesis will increase.

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Purpose of research and development

An active decorative prosthesis as a prosthetic hand that combines the merits of both a decorative prosthesis and an active technique.

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By introducing a soft fingertip mechanism, it is possible to realize a more human-like gripping motion, which is a specification that sets it apart from existing active techniques.

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Examination of the mechanism of the prosthesis

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Problem:

The wrist joints are fixed and require an unnatural posture when operating the prosthesis.

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Simulation

1. Extend your hand to the object on the table.

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• Grab an object

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• Lift vertically upward and place the object on the table again.

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• Return the hand to the initial position.

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Four types of constraints

1. Free wrist and thumb

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• The wrist joint is fixed and the thumb is free

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• The wrist joint is free and the thumb is fixed

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• Fix wrist joint and thumb

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Analysis result

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Consideration

• When the exercise is applied only to the wrist joint or only the thumb, the operability during the grasping / moving motion is improved as compared with the case where both the wrist joint and the thumb are fixed.

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• It was also found that the prosthesis can be operated with less muscle activity.

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Consideration

• However, the freedom of the wrist joint is difficult to realize in terms of control and mechanism with an internal force source, and is realized with an external force source.

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• Therefore, this time, we created an artificial hand that freely approximates only the thumb, which has the same operability as the mechanism of wrist joint freedom.

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Summary

By conducting motion analysis experiments with healthy people, it was found that the movement of the wrist joint and thumb is important when a person grabs an object.

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Summary

The newly designed design with a thumb that is easier to operate is mounted inside a commercially available decorative artificial hand.

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As a result, we realized the prosthesis that combines the merits of both the decorative prosthesis and the active prosthesis, which is the purpose of this research.

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