【Prosthetic Hands】08 First Generation - Demonstration and Summary

 After months of development, my first generation of prosthetic hand was finally close to its completion. The hand was capable of performing several gestures, including Power Grasp, Hook Grasp, Centralized Grip, Three-Jaw Chuck, Cylindrical Grasp. In addition, the wrist joint could also move.

  

(a) Power Grasp      (b) Hook Grasp     (c) Three-Jaw Chuck

(d) Cylindrical Grasp     (e) Centralized Grip

After making sure all the needed gestures could be performed, the next step is to control the hand with my own hand gestures, just as the following slide.

Here I recorded a video demonstrating how I could control the prosthetic hand with my EMG signals.

That's it! My first generation of prosthetic hand. Though the result surpassed my expectation, there were some major problems that made it impossible for this hand to be applied in the real world:

1. The length of the forearm part

As you can see in the pictures and the videos, the hand is too long for a forearm amputee to be equipped with. This is because of the goal to shrink the volume of the palm, which eventually made me relocate the actuators to the forearm part.

2. The insufficient grasping strength

As the first generation, the primary goal of the hand was not directly develop a hand that could be utilized in daily life. Instead, I wanted to test all kinds of concepts and mechanisms and see which ones were more feasible and reliable. Consequently, I did not consider the grasping strength when choosing actuators. The strength (torque output) of the actuators was eventually proved to be insufficient, which limited the objects it could lift.

3. The structural integrity 

The last primary problem is that the structural integrity of the hand was not enough, especially at the joints of the fingers. This uncertainty of joint strength impeded me to further test any objects heavier than tennis balls. The structural integrity also greatly affect the user experience. After all, people's life would not be improved if they have to worry about their new prosthesis falling apart.

Thanks a lot for finish reading these articles. If you have any question, please leave a comment below or send me an Email (tp6yk6m3@gmail.com).

In the next series of article, I will introduce the second generation of my prosthetic hand. Hope you enjoy them.