Engineering task: Build a working arm on $40 budget

Teams from Desert Shadows, Tucson Magnet earn awards at national contest in Oregon
2013-07-05T00:00:00Z Engineering task: Build a working arm on $40 budgetVeronica M. Cruz Arizona Daily Star Arizona Daily Star
July 05, 2013 12:00 am  • 

Two teams from Southern Arizona schools earned awards at a national engineering contest for their prosthetic-arm designs, created from materials including cardboard, wood, magnets and a flip-flop.

Math Engineering Science Achievement teams from Tucson High Magnet School and Desert Shadows Middle School from Nogales were among 18 teams who earned spots at the MESA USA National Engineering Design Competition, held June 21-23 in Portland, Ore.

The students were tasked with creating a prosthetic arm for a fictional teenage girl that had the ability to pick up, place, move and throw objects, all on a $40 budget. Teams also had to write a research paper, make a display and give an oral presentation.

The most difficult task was the dexterity challenge that required picking up three different-sized bolts, placing them in appropriate holes in a wooden base and then picking up the corresponding nut and threading it on the bolt, said Kerstin Moyer, who will be a senior this year at Tucson High.

The Tucson High team spent a lot of time perfecting their prototype made from wood, an aluminum angle, string, magnets and rubber bands to accomplish that task, Moyer said.

Their design used a harness that attached to the shoulder opposite the prosthetic arm and the opposable finger on the arm opened and closed when the arm was moved, Moyer said.

"To do the task it also had a lot to do with the way you angle your body because the finger only opens if you move your arm a certain way," she said.

Aside from the months of practice at the team's meetings throughout the school year and into summer vacation, she'd also practice her body orientation while doing things at home like cooking.

The hard work paid off: The team took home third place in design dexterity, design efficiency, academic display and third place overall in the whole competition.

Other members of the Tucson high team are Alicia Duran, Fernando Najera and Jonah Trujillo.

While most teams took a mechanical approach for their designs, the Desert Shadows team went a different route by incorporating electronic motors into their arm prototype.

Team member James Harrison, who is interested in robotics and electronics, came up with the idea of using small motors, called servos, to open and close the fingers. The rest of their design was made from duct tape, cardboard and a flip-flop.

As part of the competition's rules, teams were not allowed to use their free hand to control the prosthetic hand, and the team had to figure out how to operate the servos with switches, so the problem was solved with a flip-flop.

The team attached a switch in the toe area and one in the heel of a rubber flip-flip and they were activated by foot, said team adviser Roxanne Bell.

For the distance accuracy-relay part of the competition, team members had to use the arm to throw three different sized balls into different buckets at different distances, said Harrison, who just finished eighth grade.

"The design of it being controlled by a flip-flop was in our early thoughts because we wanted an easy approach when we had to throw items," said Harrison.

The Desert Shadows team was the first Nogales team to ever make it to the national competition and it won second place in the oral presentation portion, Bell said.

This was the first year Samantta Garcia was on the team. The incoming seventh-grader loves to build things.

She said the best part of her experience was "learning how to move the arm and connect all the wires and fix servos and being able to go out and compete with other people and meet other people from other states."

Other Desert Shadows team members are Juan Pablo Rodriguez, Coral Dober and alternate Ulisses Valenzuela.

(The best part) was "learning how to move the arm and connect all the wires and fix servos and being able to go out and compete with other people and meet other people from other states."

Samantta Garcia, member of the Desert Shadows team

Contact reporter Veronica Cruz at vcruz@azstarnet.com or at 573-4224.

Copyright 2014 Arizona Daily Star. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

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