Prosthetic Arm Force Reducer Team 1 – Halliday's ... - Ohio University

operation necessary. This convertibility also applies to future times when Tim receives a new
forearm from the company. Every 3 years the forearm and cable are replaced by insurance, so
Tim could do the future changeovers of the mechanical advantage system to the forearm himself
or with the help of BVR engineers. The cable should then be able to last another 3 more years
until the next changeover. As seen in Table 8.0.1, the system will last 13,675 cycles which is
approximately equivalent to 3.8 years (360 working days a year using the system 10 times per
day). This lifecycle number is based on the cable being the limiting factor.
The project met all of the specifications as outlined in Section 3.0. The following table
summarizes these specifications and relates them to the actual performance of our design.
Table 8.0.1 Performance Relative to Specifications
Specification Actual
Avg. 9.5 lbs (47%
Acceptable?
Input Force Avg. 18 lbs
Reduction)
Equivalent to 11 rubber
Yes
Closing As strong or stronger bands at hook’s highest
Force than 7 rubber bands
setting Yes
Unit Price Less than $700 Total Prototype cost $575 Yes
Unit Fit into Tim’s prosthetic Fits into Tim’s prosthetic
Dimensions forearm
forearm Yes
Unit Life 10,800 Cycles (3 years) 13,675 Cycles (3.8 years) Yes
Unit Weight Less than 5 lbs 4 lbs Yes
The true value of this design allows Tim a way to more comfortably work in the fields exerting
one-half less input force than he traditionally had to use with his former prosthetic. This will
greatly lessen the discomfort that he experiences from using the prosthetic in his daily work.
The system is easily cleanable, corrosion resistant, simple to operate, and utilizes the standard
cable and cable connectors that both Yankee Bionics and Tim are familiar with already. The
mechanical advantage system being fully contained in the forearm is extremely unique.
Currently, no product on the market like this exists. The system is very compact, yet the
materials chosen are quality and easily machineable and replaceable.
Our recommendation is to continue with our mechanical advantage project. The user would send
in his/her forearm to our company and we would install the mechanical advantage system for
them. Though maintenance is relatively simple, we would also offer maintenance and
replacement services to our customers. Our company would be in partnerships with prosthetic
forearm manufacturers such as Yankee Bionics. If we needed to modify the design to fit a larger
range of forearms, we would do so in the future to help the maximum amount of people.
The prosthetics industry is very specialized for each user. Our product can be adjusted for
different sized forearms by modifying the outer diameter dimension of the two rings. Further,
the system is bolted to the forearm using 8 rounded head bolts. The only variable tasks in our
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