Sixty or so hours later and I somehow finished the robot assembly. It’s been a week and a half of 12 or more hour days to get it done and I’m exhausted. Still nothing feels better than when you finish, flip the switch and everything goes exactly how you hoped. Unfortunately I’m not quite at that stage… maybe?
The “robot” is not quite a robot, it’s more of an assistant for people with SCI and not nearly as fancy as you may be imagining, still it’s pretty cool. The good news and bad news is that I did not build it. That’s good because it was a significant amount of time to create, the bad news is because I didn’t build it, I have no idea what’s going on with it.
I was simply the person doing the assembly. There was a ton of soldering and wire cutting, then more soldering, followed by a lot of cursing. Happily I only burned myself once and first blood went to the robot, I also somehow got a metal splinter, which is never my favorite, yet it seems to happen often. Despite those struggles and the fact that I’ve been almost exclusively hunched over the whole time so my back is not happy, the thing that kept me going was the fact that it was going to be exciting to flip the switch and see it working perfectly.
Last night, well after the hospital closed, hospital-PI and I were hard at work attaching all the electronics needed to control the robot. It was almost 11 hours at that point for the day, but we did it. Then we turned the power on and nothing exploded, caught on fire, melted, smoked, or smelled odd, a victory! That is, until we sent a command to it and nothing happened. Eventually we realized one of the connectors was (probably) flipped, this fixed part of the problem, one side worked the way we wanted, the other side however was not so lucky.
Taking everything apart we discovered that one side wasn’t turning on, but the power was routed to both so if one was on the other should be on too. After poking around we figured out that the internals got power from the cable that the connector was flipped on, so we tried flipping that sides plug as well just in case, but nothing.
Fearing we somehow burnt out the electronics, we swapped the cable and everything worked, so obviously the problem was with the cable. Well that was confusing because there are ~15 pins spread out around a four row 20 pin per row connector (I think it’s 20 pin I haven’t counted) and the two cables were definitely not soldered the same way. I wrote down a pinout diagram for one and when I did the other it was so startling that I instantly recalled it when we had this issue.
So I resoldered the cable, plugged it in, turned it on (just a few hours ago) and got zero. Since I knew the cables were the same, I figured it was something stupid. I’ll preface this by saying it’s always the little things that somehow ruin everything. The cables we were given had a cover that made the plug look very fancy and gave us the ability to screw it down to hold it in place. On a hunch I removed the cover and turned it on.
As far as I can tell, the cover has a metal bar that attaches to the cable to provide strain relief (to keep you from pulling on the soldered bits). For whatever reason the bracket was coming into contact with some of the unused pins and causing a short somehow. That’s the assumption I’m working on anyway. I’m hoping that once I add a cover to the metal tab (heat shrink is great for this by the way), once I put the cover back on everything will work how we want.
Someone’s looking out for us though, the huge meeting we had today with someone from the government to see what we’re doing, it got pushed to tomorrow. The person is still roaming the hospital, but they won’t be visiting us specifically until tomorrow afternoon. Plenty of time (I hope) to solve this mystery.
Hospital-PI has reached out to my Russian counterpart (Russian Alex) to get his input on the situation and we’re meetin here in just a few minutes. Mostly I’m confused why the two wires were soldered differently, he is apparently a little on edge, so today’s meeting will probably be a little rough if he thinks I did something wrong, but I feel a bit better knowing that the removal of the cover fixed the problem.
Technology, what a pain.