Custom protoboard of the prosthetic hand
Final version of glove hand. Electronics are not sewed on glove to provide better mobility
Glove Hand, with protoboard sewed on top
Final version of prosthetic hand, with all electronics in device
Testing the prosthetic hand with a power supply

Inspiration

Currently available prosthetics are either completely mechanical, with limited independent movement between joints, or costs thousands of dollars and require surgery to create an interface between nerves and the system. Our project proposes a way of improving low-cost prosthetics in cases where the user has an able hand, so that we can have it control the movements of the prosthetic. Therefore, adding functionality to the prosthetic by giving greater control over the prosthetic fingers to the user.

The Mirror Hand device consists of two parts, a sensor glove and a prosthetic hand. The glove reads the current position of each finger in the able hand and sends the data to the other part, where the fingers' position will be mimicked.

Goals

We established four baseline goals in order of dependency to guide our priorities for this project:

1 - Have a glove on the patient’s hand that can detect movement at individual fingers

2 - Microcontroller in glove can communicate information wirelessly

3 - Build a solid 3D printed prosthetic hand

4 - Have servo motors on the prosthetic that give us 5 degrees of freedom.

Additionally, three reach goals were created having in mind what an ideal device should be:

1 - Increase DOF of prosthetic hand

2 - Use low cost, small, capacitive strain sensors on the glove (improve accessibility)

3 - Achieve 12 DOF reading with the glove.

Milestone 1

At the point of Milestone 1, we had a glove with one sensor at the thumb, interfaced with an Mbed, capable of reading the position of the finger and sending via Bluetooth to a smartphone.

Milestone 2

At the point of Milestone 2, all the five sensors of the glove were attached, and the prosthetic was printed. The master-slave communication between the two parts started to work, however the data was sent only 5 times per second, causing the servos to not move in a fluid way.

Baseline Demo

At this point, we had achieved the four baseline goals initially created. The glove could read each sensor, send the data wirelessly, and the prosthetic hand processed the data to mimic the behavior of the glove. Additionally, we had a button to freeze the position of the prosthetic such that tasks like carrying bags and holding small objects could be made with the prosthetic hand with little interference of the other hand.

Reflections

We were proposed to update the reach goals to focus more on usability of the device. Given that we around one week, most of the reach goals were not reasonable. We opted to not make drastic changes to the hardware of the device. Instead, our new goals were to use a potentiometer as a timer for freezing the position of the prosthetic and customize parts of the hardware or software such that our device could have better functionality for disabled people.

Reach demo

We addressed concerns regarding size of the device and positioning of the electronics. The device could cover a better range of activities as you can see in these videos:

https://www.youtube.com/watch?v=0YRK3EDscS8

https://www.youtube.com/watch?v=HV1luiP_14o

https://www.youtube.com/watch?v=bbDRLOT-rF0