My goal with this project was to create an affordable, compact, and 3D printed prosthetic device with adaptive grip—all while simultaneously gaining knowledge in mechatronics and 3D design. At the time I began this project I was very interested in engineering applications within the biomedical field.

There are many technologically advanced prosthetic devices out there, but the challenge is that most of the world's population in need of them are living in third-world countries and they cannot afford them. Another challenge is that individuals with only wrist amputations cannot use many commercial prostheses because components are often stored in a forearm section. 

Due to budget constraints, this project has not been completed, and is still ongoing. More updates to come.

The design was inspired by Alvaro Villoslada and Mahdi Hussein's own takes on prosthetic hands. Check out their projects here, respectively: 

https://hackaday.io/project/9890-dextra

https://mdesigns.space/projects/compact-bionic-hand

I designed all components iteratively in SolidWorks. Inside the palm there are five high-torque DC motors, each with a spool to flex the tendons and a potentiometer for position reference, and they rest inside of the palm. There is also a servo to control the thumb's rotation inside the palm.

Figuring out how to flex and extend the fingers was fun. There are two methods to do this:

• Mimic biology and use an internal tendon-driven system (as shown upper right)

• Use stiff mechanical linkages

Each has their advantages and disadvantages. Most commercial hands use linkages because they are dependable. I opted to use tendons in order to achieve adaptable grip, meaning that when one joint encounters resistance, the other joints are still free to move. However, this presented many challenges with reliability and calibration. 

Of course, 3D printing is the only way that something with such complex geometry could be made. Plus, it's cheap. All structural components were 3D printed.

After it was printed and I had all of the motor connections soldered, I used an Arduino to control them. 

More updates coming soon!