Developing an Affordable Open-Source Bionic Hand

This project explores the feasibility of developing an affordable, open-source, bionic prosthetic hand to develop an alternative to be used in applications where traditional prosthetics are not an option. Developing a functional prototype based on proportions taken from a human hand provided a solid foundation for the rest of the project. The initial prototype served as a testbed, allowing me to test different methods of control. Such as input from an electromyography amplifier and accelerometer module, that when processed by an Arduino microcontroller can be used to control servos that open and close the hand. The project aims to provide a functional prototype, design schematics, and CAD models as reference material. To be used by others in the pursuit of developing and delivering non-traditional prosthetics options.

INTRO:
Welcome to a brief overview of my Undergraduate Student Research Project, Developing an Affordable Open-source Prosthetic Hand.

BACKGROUND:
The initial prototype I designed was part of a group project for my introduction to engineering class. It was controlled by a mobile app that connected to a microcontroller via Bluetooth module. This prototype had several shortcomings, most notably the single motor set up didn’t deliver enough power to close the hand properly. This issue was compounded by the hand’s lack of flexibility.

SECOND PROTOTYPE:
When developing the second prototype, I mitigated these problems with additional motors on the back of the hand and included a horizontal joint in the upper half of the palm, allowing the hand to flex.

FINGER DEVELOPMENT: 20 sec (show pictures of finger prototypes and them video of them flexing)
When designing the fingers, I developed multiple prototypes to test different tolerances for the hinge joints. I used dual pivoting joints for the fingers to increase flexibility and extended the supports on the back of each of the links to prevent them from flexing backwards.

MATERIALS
I tested multiple materials for this project including PLA+, PETG, and Resin. Resin provided the highest level of detail with resin. However, the most practical option was PETG. It’s stronger and more heat resistant then PLA+, and unlike resin it can be printed on a standard FDM printer.

CONTROL METHODS
I experimented with multiple control methods, using an off the shelf electromyography amplifier, also known as EMG, and custom-built amplifier. I was able to control the hand using the input from an accelerometer module. When the module detects a tilt the motors wind mono filament line closing the hand. When the module is tilted back the motors spin the opposite direction, unwinding the line and opening the hand. One area for improvement is with the EMG amplifier. I was unable to control the hand using input from the EMG amplifier.

CONCLUSION
There are some improvements that can be made to the project. Specifically, further testing of the EMG component as well as exploring other methods of control, to provide diverse control options to potential users. Additionally, certain components of the hand such as the cable guides and elastic retainers could be redesigned to print as one piece. This would also reduce and optimize the materials needed to construct it. I would also like to integrate a Bluetooth component to the hand, to allow the user to configure specific gesture presets through an app.