It seems everything and everyone has been touched in some way by the outbreak of SARS-nCov-2 also known as "the Coronavirus" or "the 'Rona" depending on whether you reside in Texas or literally anywhere else. This project is no exception. With global supply chains disrupted and local retailers all but shutdown there's a lot with my project I was unable to accomplish. While the mechanical design was completed and fabricated - it had to be made using subpar and sub-spec PLA+ rather than the designed Nylon 6-6 and ABS. Numerous parts suffer undue mechanical wear tight fitments due to this. A few design changes still should be made in light of the manufacture of the Mark 3 - most pressingly a more compact radius on the palm-wrist joint as well as designated areas for fiberglass reinforcement (A technique experimented with during the design stage but deemed unnecessary as the design would originally be cast from high strength polymers). While the mechanical side of this project definitely suffered setbacks and hits, it is more or less complete and ready to be fabricated by anyone around the world.
The true loser here was the electronics side of the project. Electromyography is an incredibly complicated and nuanced application of ultra-high gain amplifiers. It doesn't help that to do it transcutaneously one needs to be able to receive signals through human skin (which while miraculous is perhaps the worst electrode possible). Not only do you have to deal with minuscule current flow and tremendous impedance - but such signals must be almost perfectly matched in frequency to a receiving amplifier or else nothing will be readable. For this purpose a rather specialized LT1167 amplifier was needed - one which would no longer have prioritized shipping and would take too long to arrive. No control electronics means no control software. All testing was done initially with a modified EKG shield for an Arduino which proved somewhat capable for collecting basic data on nerve impulses but was far too noisy to glean useful control data from. Could it have been made to work? Definitely, suitable high frequency filters and analog gain control circuitry would have made it perfectly usable for the task - but I simply lacked the time to do so. Instead I opted to design an alternate control system but again did not have time to build it. Everyone was blindsided by the pandemic but I could have definitely prepared better for it. If I had ordered components once I designed their necessary circuits and procrastinated less into the year I would have been able to complete far more of this. I was far too tempted to leave things off until my spring break to work on them when I figured I would have plenty of time. Of course by that point the pandemic was shutting down factories and supply lines around the world. I will still of course be releasing all pertinent files completed on GitHub - but they are no-where near as complete as I would have liked.
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AuthorMy name is James Falcon Doss. I'm a member of Severn School's class of 2020 and have a passion for all forms of engineering. Archives
May 2020
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