MIT Biomechatronics Group Visit

This past Friday, Meghan and Myles went to the MIT Media lab to visit the Biomechatronics group, which researches and develops some of the most advanced lower-limb prosthetics in the world. More specifically we were there to see David Hill, a graduate student and friend of one of our professors who kindly agreed to give us some of his time. While there, we also got to meet and speak with Luke Mooney, another graduate student in the Biomechatronics group. David is on the physics side and specializes in the dynamics of human locomotion to develop a human running model. Luke is a mechanical engineer who is designing a lower-leg exoskeleton.

Admittedly, we did not enter this conversation with many specific questions. We were there to absorb whatever information we could from people deeply involved in the field and to establish some initial contacts, and we were successful on both fronts. In short, we got some advice on the direction of our project. In our discussion, Luke suggested three potential roads that this project could go down:

1.) Socket Design. Sockets are apparently one of the most fundamental problems in prosthetics today. People’s bodies are neither rigid nor unchanging, yet most sockets are designed as though they were. The Media Lab is actually taking steps already to improve on that by designing custom 3D printed rubber sockets with varying hardness regions, providing both maximum support and comfort for the user.

2.) Reading “Intent.” This refers to the idea that, since we are working with hands, we need a channel through which the user can signal a desired action to the prosthetic. In our case, this refers to the circuit we are trying to develop to read the electrical pulse of muscle contractions from the skin. Other potential methods that have been tried for reading intent include EEG, mechanical control, and electrode arrays implanted in the brain.

3.) Device Design. This is what most people think of when they think of “prosthetic design.” It refers to the design and construction of the device itself. Luke and David suggested that, to avoid unwieldy complexity, we consider making specialized limbs for different tasks since these can be much cheaper and easier to make while still providing enormous benefit to the user.

Though our team is still waiting until tomorrow to re-unite and de-brief on how this visit will affect our direction, this advice gives us a much more solid bearing on what is possible from the view of experts in the field.

More to come soon,

-The Prosthetic OSS Team

Hackathon #1

Hey everybody, sorry for the lack of blog activity lately. It has been a crazy couple of weeks so we never got a chance to report on the results of our first hackathon on September 28th!

Our hackathon table

For this six hour adventure, we had two pieces to prototype: an under-actuated finger and a muscle-reading circuit. To accomplish this, Meghan, Nitya, and Raagini took on the circuit (the hard part) while Myles CADed up a finger prototype.

With the help of cookies and Fruit by the Foot, we made a whole lot of progress on both missions. Unfortunately, the electrical signals from muscles are really hard to detect on the surface of the skin, so we never got a consistent, clean signal from the body. The circuit as we constructed it consisted of a band-pass filter followed by an instrumental amplifier. The time was not wasted, however, because the process allowed us a lot of iteration so that we can set better headings for future development.

The circuit in its fully-wired glory.

Raagini cheerfully reading signals from her cheeks.

On the mechanical end, we just barely got a 3D printed prototype cranked out by end of the hackathon. Very simple in nature, it consists of 3D printed joints (measured from Myles’ left index finger) with a couple of dowel pins as the pivots and a strings running through the front and back of all the joints, eventually coming to a loop that, theoretically, could be controlled by a servo. It is still a bit clunky, so stay tuned for a second iteration!

3D printed finger prototype with the front strung up.