While there is quite a bit a great information online regarding the various aspects of robot design, fabrication, scouting, team organization, etc., there doesn’t seem to be as much out there regarding what the higher-performing teams do to help ensure that their robots survive the rigors of competition. Our team has been fortunate to compete in the regional playoffs the past few years and one thing that we’re still learning the hard way is that these robots take an absolute pounding throughout the course of a 3-day regional competition.
So I’m curious what sorts of rules-of-thumb that you’ve developed over the years related to this. A couple that we’ve adopted:
Don’t overlook the bumpers. We were disabled 2 years ago in a quarter final match because of too much red showing on our blue bumpers. Last year we had to heavily modify bumpers in order to pass inspection at our first regional and had to re-build one set due to damage sustained over the course of competition.
Strong Battery Mount. This lesson was learned last week in Utah after 3245 (really good “De-Feeder” bot) put a beatdown on us and knocked our battery mount completely loose.
Secure All Wire Connections. Another one learned last week. Multiple runs over the RZ boundaries as well as contact with other bots during the course of the matches would rattle a surprising number of connections loose - including the battery connectors and CAN bus connectors at the PDP. We had never encountered this before and frankly had taken for granted that once they’re plugged in their would just stay plugged in.
Would love to hear others’ lessons learned / “always do” methods and processes to minimize nagging repairs and in-match failures during competition - especially during elimination matches after 2.5 days of pounding. Hopefully this will help other teams enjoy more success in competitions in the future.
In addition to the key things you said, we try to maintain a pre-match checklist of things that need to be maintained or checked out before every match. It would include a lot of the things you said, but also specific maintenance tasks like tightening up mechanisms that see a lot of wear, wiping down compliant wheels to maintain grippiness, looking everything over for proper lubrication, verifying/testing the position of mechanisms to make sure they’re in the right pre-match configuration, inspecting ropes for abrasion. Sometimes it takes until mid-season for us to get a handle on what matters and what doesn’t, so the list evolves with every competition.
Everything here is exactly correct but to change one detail. Pre-mactch checklists are completed at the 11th hour. To make the most out of the precious minutes between games you need to complete everything listed here as a Post-match checklist and systems check. It will save you the headache in the queuing before the match.
We lost a very close match when an alliance-mate’s bumpers fell off in the endgame.
We saw two batteries ejected from robots at GKC.
And this one bit us, both leads from one of our shooter motors got jostled off (thank goodness we had a picture to show which went where). They all got a good soldering after that.
I also agree having a between-match check/reset list is I think essential – you’re often pressed for time, so having a checklist helps insure everything gets done under pressure.
The final things I would add, and these are somewhat in conflict with each other, is to design for ruggedness (protecting your soft inner bits) and design for repairability (if there’s a thing that’s likely to wear out or break or get distorted or whatever, if you can’t fix the design at least make sure you can replace it as easily as possible).
One lesson we learned the hard way in 2017 was performing health checks on batteries. After ordering additional batteries, we started labeling them with the year we got them and an overall assessment (good, ok, bad, etc). We try to reserve the new/good ones for competitions, and use the decent and older ones during our meetings.
Well theoretically post match and pre match are the same thing. My team does our checklist once the robot is out of a match and into the pits, whether that is considered post match or pre match is completely up in the air. However we have a smaller checklist that is done by driveteam while in queue to make sure nothing was overlooked.
Every threaded fastener should either be secured with a locknut (preferred) or with threadlocker (not as good). Even better are zipties.
Bring spares to the competition of every actuator (motors and pneumatic cylinders) and every sensor on your bot.
Design for easily field replaceable modularity. If it’s not easy to quickly swap out any part of a mechanism, be sure you have a completely assembled spare you can swap onto your robot while the original is being repaired between matches. Be sure that hose lengths and cable lengths are identical on both mechanisms so they are drop in replacements.
If you are nervous about driving your robot full speed into a wall, you haven’t built your robot tough enough. See the beginning of our 2019 reveal video for an example.
Expect everything you extend over your bumpers to be smashed, either by defender robots, or by your driveteam ramming it into a wall. Build it so it can either take the hits, or can be easily repaired.
Protect your expensive actuators with mechanical fuses, if necessary. Mechanical fuses are easily replaceable parts designed to break before more expensive, harder to replace parts do.
Build stuff out of lexan. Aluminum bends and breaks. Lexan flexes. Use this to your advantage.
Don’t expect that just because your electronics are inside your frame perimeter that they are safe. Defender robots WILL reach into your bot. Protect your electronics with removable shielding so they aren’t damaged. Defenders might be penalized if they damage you, but that’s exceedingly rare. Even of they do get caught, you may lose the match because of their damage, and that’s not something a piddly penalty can fix. Don’t let yourself be victimized by illegal defense.
Way more common than match losses from robot damage are match losses due to driver station problems. Harden your driver station hardware and software. This video explains how to prevent one extremely common drivers station failure.
Strain relieve all your wiring connections. Run wire neatly, for easy servicing and troubleshooting. Mechanically secure your electrical connectors. Use Anderson powerpole connectors on all your heavy gauge motor wiring, and secure them with retention clips.
Overbuild your intakes or any mechanisms that are past your frame perimeter, to the best of your ability. They will get banged up by other robots. This includes mounts and pivot points, which could get broken. Anything that requires delicate alignment or precise operation should either be well protected or rethought completely.
Make sure all your electrical connections are really solid all over the robot. I should be able to reach into your robot, grab any wire and give it a solid tug. Use ferrules if you can. For PWM, DIO, etc. connectors coming off your RoboRio, tape or tie the wires down so they cannot accidentally slide off. For Anderson PowerPole type connectors, use zip ties, electrical tape, or those little locking pins, to hold them together. Test all your crimps by giving them a solid tug.
As ToddF says, you should not be nervous about slamming your robot full speed into a wall, or dropping your robot from a few inches off the ground. In fact you should do exactly this, because if you don’t, another robot will.
Stress your drivetrain by driving into a wall or spinning in circles to see if battery voltages can drop to a point where things can brown out. If they do, look into current limiting and/or replacing old batteries.
3D printed parts make good mechanical fuses. Make spares.
In addition to all of this, make sure your Pressure Release Valve and Main Breaker are easily accessible at all times, not just when a mechanism is in a certain position, or reaching in from a certain angle.
Last year, we had our breaker out in the open, in a very vulnerable spot, which caused it to be hit by cargo and shut off a couple times. To try to prevent that this year, our robot’s electronic were nicely tucked away. We didn’t realize some of what we did would be an issue until we went to get inspected at our first competition. Our intake folded down in order to intake over the bumper, with a polycarbonate plate connecting the two sides, covering the opening between the supporting axle for the intake and our bumpers to prevent balls from getting stuck there. We had mounted our main breaker on the edge of the robot, right inside of the frame, in that protected area, but underneath where the poly plate was when the intake was down. We didn’t realize this would be an issue at first because we could easily access the breaker when we flipped the mechanism up. Long story short, it was an issue, and we had to cut away material in the poly plate as well as our indexing ramp big enough for a large fist to reach down into the robot and flip the breaker. There was a similar issue with our pressure release valve. While we could easily flip it open when we reached into the robot from the side, you could not reach it from the back without going around a 2x1 support. For this, we were thankfully able to just cut the zipties and move it out into the open.
TL;DR:
Just make sure your important components are out in the open, not just out in the open sometimes.
Testing batteries is definitely important. No matter how new or unused a battery is, you can get a dud. We had an alliance-mate die mid-match because a brand new, recently tested battery had an internal failure. We test all our batteries once a year on an analyzer (we use the Andymark one https://www.andymark.com/products/computerized-battery-analyzer), because it’s not enough to just test the voltage or even use a battery beak. We definitely use the battery beak in the pit pre-match to make sure our level of charge looks good, but the only way to screen out a dud is to run through the full battery analyzer or at least use it for an extended discharge every once in a while to make sure it runs as expected.
Exactly! Einstein Runner up alliance member 5406 at Detroit worlds last year accidentally got disabled by I think some field lexan piece pushing the disable switch nestled well within their frame during Ontario district champs last year. Hopefully someone from Celt-X can confirm or refute that?
So it’s not even always just another robot taking out your electronics, can be field elements or game pieces too.
another option to testing your batteries that is specifically for FRC I would say to look at the battery test kiosk my team developed. You can find our battery presentation that we presented at worlds here. If you want more information feel free to pm me and the other electrical people on our team along with me would be more than happy to answer any of your questions. Remember batteries are possibly the most important component of your robot and its ability to compete
Either that happened to them and us or you might be thinking of our team (the former is quite likely) but that definitely happened to us during DCMP 2019 during quarterfinals. We were pushed into the cargo ship by a defense bot and somehow something in the field sliced right through an Achilles heel in our electronics mounting and cut the power to our radio. Seconds later our alliance partner was tipped over, and there went the match and our season.
Reusable zip ties around the SB50 connector. That’s my go-to fix for the second-pick robot on our alliance. Not having one cost us the 2017 district champs playoffs.
We actually prefer to use a small Velcro strap around the battery connector. Zip-ties can break loose due to impacts and such, the Velcro strap has been the most fool-proof method we have found for never coming loose.
Also we use a large Velcro strap for securing the battery itself to the robot in whatever battery tray the robot has that season.
