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When Compared to natural human wrist function, the motions of extension and flexion do not compare. However, mobility in this aspect lacks across most types of body-powered prosthetics. The main aspect of this design is that extension is roughly the same as the original design, as that is what determines the grip strength of the device.
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The most important aspect of analysis is how the modified rotational movements compared to the natural wrist motion. As shown, the device was well within the desired range of motion.
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The graph illustrates the ability of the device to produce the same values over an extended period of time. The data listed is reflected of the original design (0) and the modified design(1).
Test 1: Range of Motion
The Raptor Reloaded prosthetic hand was modified with the intention that it could allow more degrees of freedom in the wrist without sacrificing grip strength. It is expected to be more adaptable in its mounting capabilities as well. In regards to the to the degrees of freedom, it should be capable of an extension of 70 degrees and a flexion of 75 degrees, as well as an internal rotation (pronation) of 20 degrees and an external rotation (supination) of 30 degrees about the longitudinal axis in transverse plane of the wrist. The transverse plane will be the cross-section of the wrist and the longitudinal axis is one that goes straight through that cross-section. All motion references are assumed to be in anatomical position.
Results 1: Range of Motion
Complications in testing the range of motion for a device that can rotate as well as flex and extend, means that getting readings on a purely axis by axis basis is rather difficult. This is due to the fact that the device has a tendency to rotate as well as extend or flex, so reading may be off when only analyzing one aspect.
Schedule/Budget: Range of Motion
*There was no budget for the testing portion of this project, as all items were available at the University
Testing Complications 1: Range of Motion
APPLICATION
BUILD
The grip strength of the modified prosthetic hand was measured using a scale. The hand was set on a block where the fingers rested on the surface plate of the scale. After zeroing out the scale, the gauntlet was rotated down to it's maximum flexion capacity and the value on the scale was recorded. The test was done on both the original design and the modified design to compare results.
Testing Reports
Test 2: Grip Strength
The grip strength test showed that the modified design at its maximum difference had a strength of .07 lbf less than the original design and at its best was roughly equal to the original design strength at about 1.21 lbf.
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The difference in strength capability was due to the interference of the socket and the gauntlet limiting it's range of motion.
Result 2: Grip Strength
For the grip strength test I wanted to use a hand-held dynamometer. I was able to get a hold of one, but the minimum the grip strength of the hands were not enough to be measured on the device.
Testing Complications 2: Grip Strength
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