College - Author 1

College of Engineering

Department - Author 1

Biomedical and General Engineering Department

Degree Name - Author 1

BS in General Engineering

Date

6-2019

Primary Advisor

Jim Widmann

Abstract/Summary

The purpose of this project was to devise a solution for Jorge Segura, a US Marine who was wounded in Afghanistan and had to have his non-dominant arm amputated above the elbow. His current prosthetic attachments are not suited to cooking tasks, so he needed a way to cook more effectively with either prosthetic attachments or accessibility devices. The main tasks that he needed help with was holding down food on cutting boards and stabilizing pots, pans, and bowls especially when stirring. After background research, exploring commercially available devices, and talking with our challenger, our solution was to design three prosthetic attachments with a quick-change wrist to enable Jorge to stabilize pots, pans, and bowls, as well as hold food down on a cutting board and switch between the attachments efficiently.

The quick-change wrist operates in a twist-and-lock fashion, with the wrist inserts mating into the wrist receiver and locking into place with magnets on each component. The wrist receiver easily mates with Jorge’s current wrist so that he can efficiently and easily install our quick-change wrist into his existing wrist. The wrist is predominantly made from delrin to reduce weight and improve component machinability. The prototyping process for the wrist cost $144.58 to develop our functional prototypes, while the estimated mass production cost is only $13.99 per wrist assembly.

The clamp attachment interfaces with Jorge’s current body powered prosthetic arm through a connector plate mounted on the attachment body. Jorge is able to engage the cable to open the clamp so that it can fit over various sizes of pots and bowls, and release the tension in the cable to allow it to close over the pot or bowl. The clamp is also fully adjustable, with a trifold face designed with springs to conform to different diameters, and an angled guide that is adjustable with thumb screws to allow Jorge to angle the trifold to fit on curved bowls. It also includes a set of angled and straight inner prongs that can be removed for easier cleaning. The clamp is predominantly made from aluminum to reduce weight, and has an estimated cost of $209.55 to develop our functional prototypes, while the estimated mass production cost is only $43.25 per clamp assembly.

The sleeve attachment allows Jorge to stabilize shallow pans with long handles. The design includes a simple diamond-shaped opening to fit over a variety of pan sizes, and has no moving parts for simplicity. Made from a 3D printed core and sheet metal inserts and connections, the sleeve is relatively lightweight and easy to manufacture. Design development to make our sleeve prototypes cost $124.91, while the estimated mass production cost of one sleeve is only $8.05.

The cutting tool attachment enables Jorge to secure various sizes of food onto a cutting board. It is made of clear acrylic to allow Jorge to receive visual feedback from what he is cutting. The design of the cutting tool attachment includes several ridges to allow for better grip, and a narrow slit on the base to allow for perpendicular knife cuts. The cutting tool has an estimated development cost of $70.86 for the prototypes, with an estimated mass production cost of $4.72 per assembly.

For future manufacturing of the wrist, we recommend that the wrist inserts be made from aluminum instead of delrin to improve the strength of the epoxied and press-fit joints. This would increase the weight of the device and decrease the cost slightly. We recommend that future iterations of the clamp include a more robust prong design, and a more secure connection for the angle guides. To manufacture more copies of the sleeve, we recommend adding a key to both sides of the connecting rod to fully restrain the rotation of the connecting rod. This would increase the weight and cost of the sleeve marginally. Finally, for future iterations of the cutting tool we recommend looking into a solid construction cast from food-safe resin in order to improve cutting tool durability with respect to impact loads.

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