During my final year of college, I was tasked with leading a team of four Mechanical Engineering students in order to create a prosthetic limb for a dog from Boulder Colorado with only three legs.

Pictured on the left is Drake, the Dog. Sadly, three years ago was hit by a car leaving one of his front limbs unsalvageable and the other with severe nerve damage. Without the use of a prosthetic limb, Drake would put too much weight on his remaining front limb. Weighing in five pounds and only staying on for ten minutes at a time, Drake's old prosthetic limb proved ineffective at providing the support you would expect from a modern day prosthesis. Not to mention, the prosthesis cost $2000 which is much too expensive for what Drake was getting. With this information, my team worked closely with Drake to design a lightweight, affordable, and easy to use prosthetic limb for him and his owner.

Pictured on the left is the original prototype with our final design pictured on the right. In both designs, we split the prosthetic into three sub-assemblies titled the socket, pylon, and foot. The main difference between the two designs would be the sever reduction in components. Whereas the first design required over 80 components, our final design used 13 custom components and only 20 fasteners.

The purpose of the socket sub-assembly is to create an interface between the residual limb and the rest of the prosthetic. Our socket was designed by taking a fiberglass impression of Drake's residual limb, and then 3D scanning the imprint into Solidworks. That way, we were able to create a socket that fits nicely to Drake's leg. We 3D printed our design using a Form 2 3D printer, printing the socket out of the Durable resin.

The purpose of the pylon sub-assembly was to provide rigid support as the Drake walks, while also creating some points of adjustment for the owner. The yellow and red pieces mate together in several different angular positions, allowing for the angle of attack of the prosthesis to change in 18 degree increments. Furthermore, the yellow and orange components thread together to allow fine vertical adjustments to change the total height of the prosthetic limb. All components in this assembly were printed on the Form 2 with the machinable resin from Form Labs.

The foot sub-assembly provided a strong base for the prosthesis, while also mimicking the natural stiffness in the walking gait of a dog. This part was manufactured with a precise number of fiberglass strands within the C-shaped foot. Furthermore, we added a leaf spring that can be added to increase the stiffness of the foot if more stiffness is desired. 

When finished, our prosthetic limb fit Drake, weighed half a pound, and cost the team $116 to manufacture. Although there are still improvements being made, we felt that our project was successful in creating an improvement to the current consumer prosthetic products on the market today, both aesthetically and functionally.