Hackaday Prize Entry: A 3D Printed Prosthetic Foot

For the last few years of the Hackaday Prize, there have been more than a few prosthetic devices presented. Almost without exception, the target for these projects are prosthetic hands. That’s a laudable goal, but mechanically, at least, feet are much more interesting. A human foot must sustain more than the weight of the human it’s attached to, and when it comes to making this out of plastic and metal, that means some crazy mechanics.

This Hackaday Prize entry is a complete reversal of all the prosthetic limbs we’ve seen before. It’s a prosthetic foot, and in the tradition of easily made and easily modified prosthetic arms, this prosthetic foot is mostly 3D printed.

A foot will take a lot more abuse and weight than a hand, and because of this 3D printing all the parts might not seem like the best idea. Exotic filaments exist, though, and the team behind this project does have access to a few pieces of test equipment in a materials engineering lab. With the right geometry, everything seems to support the load required.

There are some relatively new twists to this 3D printed prosthetic foot, including electronic control, a micro-hydraulic power plant, and sensors to measure and adjust the user’s gait. It’s all very cool, and deserves a lot more engineering than even the most complicated 3D printed prosthetic hand.

Hackaday Prize Entry: Robotic Prosthetic Leg Is Open Source And 3D-Printable

We’ve been 3D-printing parts for self-replicating machines before, but we’ve been working on the wrong machines. Software and robotics engineer [David Sanchez Falero] is about to set it right with his Hackaday Prize entry, a 3D-printable, open source, robotic prosthetic leg for humans.

[David] could not find a suitable, 3D-printable and customizable prosthetic leg out there, and given the high price of commercial ones he started his own prosthesis project named Drakkar. The “bones” of his design are made of M8 steel threaded rods, which help to keep the cost low, but are also highly available all over the world. The knee is actively bent by a DC-motor and, according to the source code, a potentiometer reads back the position of the knee to a PID loop.

drako_footWhile working on his first prototype, [David] quickly found that replicating the shape and complex mechanics of a human foot would be too fragile when replicated from 3D-printed parts. Instead, he looked at how goat hooves managed to adapt to uneven terrain with only two larger toes. All results and learnings then went into a second version, which now also adapts to the user’s height. The design, which has been done entirely in FreeCAD, indeed looks promising and might one day compete with the high-priced commercial prosthesis.

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Artificial Leg Comes with a Normal Gait!


Did you know over 50% of amputees take at least one fall per year due to limited prosthetic mobility? That compares to only about a third of all elderly people over the age of 65!

[Professor Mo Rastgaar] and his PhD student [Evandro Ficanha] set out to fix that problem, and they have come up with a microprocessor controlled prosthetic foot capable of well, to put it bluntly, walking normally.

Working with a scientist from the Mayo Clinic, the pair have created a prosthesis that uses sensors to actively adjust the ankle to create a normal stride. Commercially available prosthetics can do this as well, but can only adjust the foot in an up-down motion, which is fine — if you only plan on walking in a straight line. In addition to having an ankle that can also roll side-to-side and front-to-back based on sensor feedback, they have also moved the control mechanism up the leg using a cable-driven system, which lightens the foot making it easier to use.

We find the test apparatus almost as interesting as the prosthesis itself. The researchers had to come up with a way to measure the performance of the prosthesis when used to walk in an arc. The solution was the turn-table treadmill seen above.

If you have time, check out the video demonstration on the main article’s page which covers the leg and the treadmill build.

[via Reddit]