Friday, September 5, 2014

GenCon 2014 recap

 I went to GenCon 2014 and had a great time.  I made the two-day drive out along with my wife and another friend, staying over in western PA because I'm getting a little too old and weary to drive 13 hours in one day.  Next year I might fly instead.

GenCon itself was, as always, hugely crowded (something like 56,000 attendees this year?).  Despite that the convention itself ran smoothly.  The Will Call line was amazingly fast and efficient this year, and the convention center itself seems to still have plenty of room.  The surrounding city is showing more strain, getting housing was a nightmare and getting food required waiting an hour or more in line.

Most of my time at the convention was spent gaming.  I go to GenCon for the gaming events, and this year I was fortunate enough to get into nearly all of my first choice of events.  When I wasn't at games, running between events, or waiting in line at the food trucks I did manage to get several hours of demo time in with the new little walking robot.  The robot did great - held up through the entire convention, and ran through about four of the five battery packs I had for it each day Thursday, Friday, and Saturday.  Radio reception was only a problem when the antenna came loose from the transmitter - easily fixed by screwing it back on tightly, but I might want to secure it better for next time.  It had enough traction to walk well on the convention center carpet.  Tile floors were a problem, so I avoided them, and I never got around to trying it outside.

I don't have any video of the robot at GenCon yet.  Running the robot takes two hands, and I can't work a camera and make the robot walk at the same time.  I've been looking on Youtube for uploaded videos of it, but haven't found any yet.

I did go through some spare parts.  I had two servos fail due to the robot switching on while still in my carrying bag.  I was in the habit of keeping a battery half-inserted while walking around with the robot in the bag, so it would be easier to pull out and switch on for a demo.  It turns out that if I hit the robot just right I would jostle the battery into place enough to power on the robot.  The first thing that the robot does when powered on is center all the servos, and when this happens while in a confined bag it can result in stripped servo gears.  I will be updating the software in the robot so that it doesn't send any motion commands to the servos until it receives a valid radio signal.

I had two servos in the robot destroyed when someone stepped on it.  I don't know if it was on purpose - I had originally thought not, but the person who did laughed and ran off when I confronted them, so it may have been intentional after all.  Fortunately it was easy enough to repair the damage to these and the other two failed servos.  I didn't even have to remove them from the robot, just open them up enough to swap the gears out.

One servo failed spontaneously when the feedback system failed.  It locked up at one end stop, and then when I tried to test it erratically smashed back and forth between the travel limits until the gears failed.  I haven't taken it apart enough to find out what the problem was - I suspect a broken wire or solder joint, but when the servos cost less than $3 each I'm not inclined to put much effort into troubleshooting them.  This was a slightly more difficult job than the others since I had to replace the entire servo, which also required taking the core of the robot apart to get at the wiring.  Still not a big deal, the bot was designed to be modular and I had all the tools and spare parts in my convention bag.

Late on Saturday night the transmitter failed, a broken connection in the wiring to the left-hand joystick.  I didn't have the tools with me to troubleshoot or repair the damage, and was just about ready to collapse in exhaustion anyway, so I just packed it up and was done with the robot for the convention.  The transmitter was re-used unchanged from the previous robot, and is really in need of a complete tear-down, redesign and rebuild soon anyway.  The failure only meant that I wasn't able to show the robot off on Sunday, which was not much of a loss since Sunday morning was when we were packing up and heading home anyway.

The robot was a great success at GenCon.  Up; until Sunday my demo time was only limited by the amount of free time I had between events, which admittedly wasn't much.  I never ran out of battery packs, but I did get down to my last pack for the day more than once, so I didn't have much wasted capacity.  I only had one servo fail due to non-external causes.  That last bit really surprised me - I was expecting these cheap servos to fail just from the effort of walking around, but they held up far better than I expected them to.

The big question everyone kept asking was where I got the robot - and when I told people I made it myself, was I planning to sell them?  I'm still not ready to actually sell working, finished, consumer-ready robots.  It's a huge investment in time and money to actually set up, and I really don't want to be the one doing customer support for a potentially large number of hand-made robots breaking in the field.  While the robot itself seems to work for a while without breaking, the servos are fragile and easy to break with careless handling.  Furthermore, I'd still be hand-making each robot, and even with the 3D printer it takes a while to build all the pieces for one.  That means a lot of my time invested in each sale, and I'd have to charge an unreasonable amount to make it worth my time.

I do plan on publishing the 3D files, schematics, and source code so people can make their own reproductions of the robot.  I may be willing to sell kits of parts at some point as well.  Stay tuned.