Team Members:  John Dewing, Daniel Dugan Dotson, Samantha Galicinao, Christopher Urasaki

Mentor:  Alan Strasbaugh

Faculty Advisor:  Dr. Lily Laiho

QL+ Program Manager:  Vanessa Salas

QL+ engineering students from Cal Poly were tasked with the challenge of designing and building a prosthesis for use on the sand for QL+ Challenger, Sgt. Brady. After consulting with Sgt. Brady and QL+ and performing extensive research, this team defined customer requirements and engineering specifications to meet these requirements. Comfortability, durability, and sand proof were key customer requirements.

Several conceptual models were brainstormed and a final design was selected based on the best design concepts of all considered models. The first prototype was composed of aluminum, carbon fiber, and polyurethane rubber -- all waterproof, sand proof, and non-corrosive materials -- and includes a curved toe design and rubber block used to mimic a flexing ankle and thus improve comfortability and functionality and several drains to waterproof and sand proof the prosthesis.


Manufacturing occurred on the Cal Poly campus utilizing the Mustang 60 machine shop, the Cal Poly Composites Lab, and the QL+ lab.  Funds were available to outsource parts if needed.  The Sand Foot team manufactured the first prototype and sent it to Sgt. Brady for product testing and feedback. Unfortunately, the carbon fiber sole broke in transit to Sgt. Brady, and a thorough investigation determined the break was caused by impact.  Poor manufacturing practices and unfamiliar materials resulted in a brittle sole.

The team quickly pivoted and redesigned the sole using aluminum tubes, aluminum fittings, and canvas.  The new design featured a curved toe and fit with the intended flexing ankle mechanism.  A local amputee tested the final design. The amputee positively comments on the prosthesis’ functionality and comfort, while weight, shape, and whether it was sand proof were concerns. The feedback was helpful for the team as well as engineers and student who wish to adapt the design and improve others’ quality of life.