WO2015060793A1

WO2015060793A1 - Bionic and hybrid prosthetic hand embodiment

Info

Publication number: WO2015060793A1
Application number: PCT/TR2013/000363
Authority: WO
Inventors: Erkan KAPLANOGLU
Original assignee: Ozyegin Universitesi
Priority date: 2013-10-25
Filing date: 2013-12-27
Publication date: 2015-04-30

Abstract

The present invention relates to an active hybrid prosthetic hand working with Electromyography (EMG) signals taken on the front arm, so as to provide a hybrid embodiment by using the shape memory alloy (SMA) and DC motors at the same time, characterized in comprising flexor tendon facilitating the closing movement of the fingers; extensor tendon which is located at the back part of fingers, not in alignment with the palm, and which helps said phalanges springs (4) for the extension movement of the fingers; flexor-actuator SMA which provides the hand to close and grasp and which is connected with the flexor tendon; extensor-actuator SMA which facilitates the returning movement of the fingers by making an extension movement following the grasping and which is connected with the extensor tendon.

Description

DESCRIPTION

Bionic and Hybrid Prosthetic Hand Embodiment Technical Field

The present invention relates to hybrid artificial organs.

The present invention especially relates to active hybrid prosthetic hand which works with Electromyography (EMG) signals taken on the front arm.

State of the Art

Currently, as a result of the researches conducted on the prosthesis users, it is found out that the factors relating to the performance of a prosthetic hand are the functionality, interaction with the surrounding, low weight, high speed of grasping and power, being noise- free or minimum level of noise and visuality.

The ideal prosthetic hands need to meet these criteria. In order to provide the "grasping" function in the active prosthetic hand embodiments available in the state of the art, various kinds of direct current motor are used on the part which moves the fingers.

The functionality and the grasping power in the systems that are moved by means of direct current motor are high. However, the system works in a noisy way, and it poses a disadvantage compared to a normal human being hand in terms of natural view of a hand and its weight.

Although not that common, in some of the robotic hand embodiments, Shape Memory alloys are used. Shape memory alloys (SMA) are the materials with shape memory which can turn into its original shape from the temporary shape that it is in with the effect of the surrounding stimulators such as temperature, pH, light by preserving its original shape within its memory. In the robotic prosthetic hands where SMA is used, on the other hand, the grasping speed and power is not at an adequate level compared to the healthy hands because of the general characteristic of SMAs. Moreover, it is also considered as a disadvantage that the reaction duration of the SMA used in the prosthetic hand is long. The international application with the number WO2010080774A2 relates to a prosthetic finger activator and a method of activating that prosthetic finger. For the tendons of said finger embodiment, SMA is used as the smart material. Therefore, the prosthetic finger comprises more than one cable/connection made of SMA material and each cable/connection comprises a cooling mechanism within itself. The smart material used in this embodiment is only SMA (Shaped Memory Alloy).

The American application numbered US6379393B1 , on the other hand, relates to a robot hand embodiment which is activated with the memory-smart materials. Within the patent- protection, an electrical structure is mentioned which enables the robot hand to be activated and moved. As it is seen in the figures of the relevant application, the embodiment comprises items (item numbered 210 in US application) equivalent to the flexor tendon (5). However, no item is available which is equivalent to the extensor tendon (6). Moreover, it is not possible to use DC motor, shape memory material and said tendons (5,6) simultaneously in one single embodiment.

The hybrid prosthetic hand embodiment according to the present invention provides a solution for a technical problem different than the technical problems that the above- mentioned application has solved.

Consequently, because of the above-mentioned disadvantages and the insufficiency of the current solutions, different than the known methods, it has become necessary to provide an improvement or development in the field of bionic prosthetic hands. Object of the Invention

The object of the present invention which is created with an inspiration from the current conditions is to eliminate the disadvantages related to the above-mentioned bionic hand embodiments and to the materials used in those embodiments, and to improve the bionic prosthetic hands.

The main object of the present invention is that said hybrid hand can fulfill the daily-life activities and it can be used in a lighter and more effective manner. Another object of the present invention is to provide a high grasping speed and power by using DC motor in the first three fingers as they are more actively used than the other two fingers (ring and little fingers). Another object of the present invention is to provide a hybrid embodiment by making use of DC motor and shape memory alloys. A further object of the present invention is to provide light and noise-free working by using SMA actuator in the ring and little fingers which move less compared to the first three fingers.

Another object of the present invention is to decrease the duration of SMA reaction by using extensor tendon.

An object of the present invention is to extend the battery life by making use of SMA actuator. Another object of the present invention is to provide low weight, natural view, noise-free working and low energy-consumption which are necessary for a prosthetic hand performance by making use of SMA.

So as to fulfill the above-mentioned objects, the present invention relates to a bionic hybrid prosthetic hand embodiment comprising phalanges springs providing the fingers to return back following the grasping; so as to provide a hybrid embodiment by using the shape memory alloy (SMA) and DC motors at the same time, wherein it further comprises;

Flexor tendon facilitating the closing movement of the fingers;

Extensor tendon which is located at the back part of fingers, not in alignment with the palm, and which helps said phalanges springs for the extension movement of the fingers;

Flexor-actuator SMA which provides the hand to close and grasp and which is connected with the flexor tendon;

Extensor-actuator SMA which facilitates the returning movement of the fingers by making an extension movement following the grasping and which is connected with the extensor tendon.

In a preferred embodiment of the present invention, each of the ring and/or little fingers has flexor tendon.

In a preferred embodiment of the present invention, there is a flexor-actuator SMA which is connected with said flexor tendons available in the ring and little fingers. In a preferred embodiment of the present invention, each of the ring and/or little fingers has extensor tendon. In a preferred embodiment of the present invention, there is an extensor-actuator SMA which is connected with said extensor tendons available in the ring and little fingers.

In a preferred embodiment of the present invention, each of the thumb, index and middle fingers has at least one DC motor.

The present invention, in its preferred embodiment, comprises electromyography (EMG) signals taken on the front arm, which enable said prosthetic hand to work.

The structural and characteristic aspects and all the advantages of the present invention will be more clearly understood by means of the following figures and the detailed description written with certain references to these figures, and therefore this detailed description should be considered while making the evaluation.

Figures for a Better Understanding of the Present Invention

Figure 1 is the general view of the hybrid prosthetic hand embodiment according to the present invention.

Figure 2 is a view belonging to one of the fingers of the hybrid hand embodiment according to the present invention, wherein said fingers comprise flexor and extensor tendon.

Description of the Part References

1. DC Motors

2. Extensor-actuator SMA

3. Flexor-actuator SMA

4. Phalanges springs

5. Flexor tendon

6. Extensor tendon SMA: Shaped Memory Alloy

DC: Direct Current The drawings do not necessarily need to be scaled and the details which are not necessary to understand the present invention may have been ignored. Apart from that, the elements or process steps which are identical to a great extent or which have at least identical functions to a great extent are shown with the same reference numbers.

Detailed Description of the Invention

In the hybrid prosthetic hand embodiment according to the present invention, different than the prior embodiments, all the fingers of the prosthetic hand are moved by means of a hybrid structure instead of only one single actuator (only DC motor or only SMA).

As the tendon-effect actuator of the two fingers (Little and Ring Fingers) which are a part of the developed hybrid hand, SMA (2,3) is used. As the other three fingers have more functions compared to the other two, they are moved by means of brushless DC motor (1).

The hybrid hand according to the present invention has been developed so that it can fulfill the daily-life activities and be used in a lighter and more effective manner. Therefore the actuators (2,3) have been selected in a way that they can meet necessary power and speed requirements so as to fulfill these conditions and the drivers are developed accordingly. The drivers which are constituted with power electronics elements are current control driver circuits working with pulse width modulation (PWM).

The actuator used for the flexion movement (closing) of the hand is the flexor-actuator SMA

(3) . Following the flexion movement of the hand, the grasping function takes place.

The extension movement (opening) of the hand is provided by means phalanges springs (4) in the fingers (thumb, index and middle) that are moved with DC motor, and by means of SMA extensor tendon (6) in the fingers (ring and little) which are moved with SMA. In the current embodiments, there is a flexor tendon (5) available which helps the closing movement of the hand. However, in the hybrid prosthetic hand embodiment according to the present invention, as different than the other prosthetic hand embodiments, a channel is created on the outer part of the fingers moved with extensor-actuator SMA (2) and flexor- actuator SMA (3). In this channel, extensor tendon (6) is located as a second tendon. Thanks to this second tendon, a help is provided to the spring system (phalanges springs

(4) ) for the extension (opening) movement of the fingers. The SMA used as the extensor tendon (6) has the same technical characteristics with the SMA used as flexor tendon (5). Therefore a natural hand behavior is observed.

In the hybrid prosthetic hand embodiment, by making use of actuator SMAs (2,3), the factors such as low weight, natural view, noise-free working and low energy-consumption which are necessary for a prosthetic hand performance are fulfilled. By making use of DC motor (1), high grasping speed and power is obtained.

In this detailed description, the preferred embodiments of the hybrid prosthetic hand which is embodied simultaneously with the SMA and DC actuators according to the present invention are described only for the subject to be understood better.

Claims

1. A bionic hybrid prosthetic hand embodiment comprising phalanges springs (4) providing fingers to return back following grasping; so as to provide a hybrid embodiment by using the shape memory alloy (SMA) and DC motors (1) at the same time, characterized in further comprising;

- Flexor tendon (5) facilitating closing movement of the fingers;

- Extensor tendon (6) which is located at back part of fingers, not in alignment with palm, and which helps said phalanges springs (4) for extension (opening) movement of the fingers;

- Flexor-actuator SMA (3) which provides hand to close and grasp and which is connected with the flexor tendon (5);

- Extensor-actuator SMA (2) which facilitates returning movement of the fingers by making an extension movement following the grasping and which is connected with the extensor tendon (6).

2. A bionic hybrid prosthetic hand embodiment according to Claim 1 , characterized in that each of ring and/or little fingers comprises flexor tendon (5).

3. A bionic hybrid prosthetic hand embodiment according to Claim 2, characterized in comprising flexor-actuator SMA (3) connected with said flexor tendons (5) available in ring and little fingers.

4. A bionic hybrid prosthetic hand embodiment according to Claim 1 , characterized in that each of the ring and/or little fingers comprises extensor tendon (6).

5. A bionic hybrid prosthetic hand embodiment according to Claim 4, characterized in comprising extensor-actuator SMA (2) connected with said extensor tendons (6) available in ring and little fingers.

6. A bionic hybrid prosthetic hand embodiment according to Claim 1 , characterized in that each of the thumb, index and middle fingers comprises at least one DC motor (1).

7. A bionic hybrid prosthetic hand embodiment according to Claim 1 , characterized in comprising electromyography (EMG) signals taken on front arm which enable said prosthetic hand to work.