Nightmare Repairs At Competition

In 2010 at the championship in our second to last match on Friday we fell off the bar when our climbing cable crimp failed.

We had to rebuild half our articulating drivetrain in 70 minutes between matches to get back out for the last match of the day. We knew we needed to prove to everyone our robot was functional before pick lists were made that evening. We had most of the inspectors in the division and a couple of nearby teams watching the whole ordeal because they couldn’t believe that we had planned for this, had the parts ready and actually pulled it off.

Our plan worked we were back together and played our last match. The event effect divisional picking in our favor allowing this to happen…
http://www.chiefdelphi.com/media/photos/35698

I have never been prouder of our students than that day because of how they handled this situation. Our mechanical team in the pits knew what they had to do and did it no griping no issues, just get it done as fast as we can.

In 2011 our team used a crab drive from 221 robotic systems for our drive train. It was set up with a window motor steering all 4 modules together, but the window motor was overheating frequently at both of our regional competitions. This led to the thermal switch in the window motor tripping and our modules would stop steering as a result. At Connecticut we ended up switching out one of our modules for a spare, thinking that perhaps the axial shaft of the module was too “beaten up” (it appeared fairly marred as compared to what we expected). This turned out to be the wrong explanation, but we left the module in anyway since nothing had changed for better or worse.

Upon returning back home, we noticed a thin ring of metal that appeared shaven on the bottom plate of the swerve module. We then reasoned that the likely reason for the window motor issues was this rubbing between the bottom plate of the swerve modules and the bottom of the frame. We came up with a plan for how to deal with the issue if this was in fact the problem at Championship, since not being able to drive would be the worst thing that could happen. We gathered thrust bearings and material for spacers to be machined once we arrived if we found this was the issue.

On Wednesday night at Championships, we send in our five people: me, our pit mentor, our driver, a programmer, and the programming mentor. We used a piece of paper to see if the pieces of metal that we suspected to be rubbing were. 3 out of the 4 modules had the issue, so we had to add thrust bearings in the axle shafts, get the bronze bushings that the snap rings sat on turned down, and have several delrin spacers machined to the proper height. In 3 hours we ripped apart the entire drive train, got the machine shop to precision machine 20 parts for us, put the drive train back together, then ran some systems test. The drive train worked beautifully for the rest of the competition, and had our autonomous worked or a button on our controller (of course the all important minibot deployment button) not failed, we may have been selected for eliminations.

The best part was returning to the hotel and reporting back to the team what we had accomplished. One of the kids said completely seriously, “You mean you ONLY got the drive train fixed!?!?”

West Michigan District 2011, we destroyed our drivetrain.

One of the bolts in the drivetrain came loose during a match, and the wheels on that side stopped turning. The drivers kept driving on it because they had no way of knowing if it was an electrical, code, or mechanical problem. I didn’t see the match because I was cleaning the pit, but when they brought the robot back after the match, I nearly cried.

http://d3j5vwomefv46c.cloudfront.net/photos/large/260447392.jpg

Unfortunately, this is the best picture I have. You can’t see the full extent of the damage, which is several chunks/teeth missing. I think there was some damage to the chain and maybe the axle it was on, but I don’t remember - I wish that in our state of panic, we would have thought to get a picture. It was bad. That sprocket was on the center axle and was welded to a hub with another sprocket to form a sandwich. We sent the sandwich and a new sprocket with a mentor allllll the way to the machine shop on the other side of campus to be welded and worked on cleaning all the metal shavings out of the robot and fixing other problems (it turns out that 24V valves in your pneumatics won’t work too well) while waiting for it to come back.

Mentor comes back with the destroyed sprocket (IIRC it wasn’t bent that badly before sending it there, that was just a result of getting it off of the sandwich) and the new sandwich…which was still not usable. Apparently the welding machine jumped and the result was a tooth that was completely missing and some other tooth deformation. Sent it back to see if anything else could be done, and asked frantically through the pits to see if anyone else had a spare sprocket that we could have. We found one, and decided to drill some holes in our only spare hub and bolt everything together. Ten minutes of ratcheting and two sore wrists later, we had a sandwich that was usable.

It was by no means the best fix, but we had already missed several matches and our next one was in a few minutes. We made it out to the field literally just in time to play for our last match of the day.


Not a nightmare repair at the competition, but definitely a pain in the everything:
http://www.chiefdelphi.com/media/photos/35270
See that bent corner? Having to attempt to straighten it after every match that we moved in was the bane of my existence that year. That robot was all about poor design choices, and the frame was one of them.

http://i.imgur.com/byyZ9qwl.jpg](http://imgur.com/byyZ9qw)

This is a picture in the middle of the repair. The ‘before’ – which I don’t have a picture of, unfortunately – was pretty terrible.

We collided with 360 at full-speed midfield. Our frame, which wasn’t designed to play the kind of defense we ended up playing in Portland because of a too-complicated collection system, completely collapsed. The front cross member bent inward as far as the intake roller and split in half at one of its rivet holes. The left-side frame rails collapsed as well. There are ripples in the flanges along the entire length of the left-side of the robot.

The rear-mounted gearbox and final gearing stage were knocked wildly out of alignment. The gear mesh distance was busted up and destroyed the teeth on the final gear attached to our wheel. None of the wheels remain planar with one another.

http://www.youtube.com/watch?v=r_OZi6iBhoA&feature=youtu.be at about 2:35.

We fixed it with a hammer and by riveting some aluminum angle along the front edge of the robot to keep everything square. The drive gearing remained mostly broken for the rest of the event; we were able to adjust it before each match so we could drive, but it’d go bad by the end.

We’re replacing some of the frame parts at our event this weekend and replacing the gear stage with another chain and sprocket stage. We’ve also rebuilt our entire frisbee collection, storage and shooting system.

Some of this will be nightmare repairs, and some will be just nightmare problems. As a caution, this might be kind of long.

2009 - Troy District:

  • Get hit by a robot at some point, breaks ball collection, add protective metal bar in front of replacement (nightmare is that it was held with zipties), zipties slip in quarterfinals, sole reason we don’t advance to semis :(.

2011 - West Michigan District?:

  • Try hanging a tube, I think in autonomous, and we managed to get our robot’s lift jammed to the hooks. That was interesting to remove from the field, especially as I think the window motor thermal lock probably tripped.

2012 - Traverse City District:

  • Robot falls over from bridge, bends lots of things, but we weren’t using them, so they just get taken off.

2013 - Traverse City District:

  • It is the semifinals, and if I recall correctly, we were unable to shoot discs our first match. After metaphorically banging my head against the wall for a few moments, I realize that its victor isn’t powered and the WAGO connection has come out. We take a time out and set to putting it back in (even though we got it done in enough time [read: almost to the second] that we didn’t really need it, but a time out once called isn’t easily rescinded). Able to shoot that second match, but our competition beats us and goes on to win the whole thing.

2013 - St. Joseph District:

  • It is Thursday, and we wonder why the shooter isn’t working, after having little mechanical difficulty with the shooter at TC. We determine that the gearbox (bought this year!) is slipping under load when trying to shoot, meaning the arm cannot move. We finally determine that a gearmotor from spare parts will work, and get it put on for Friday.
  • It is Friday, so many things go wrong all day, but no nightmare repairs (mostly small, annoying ones). The worst was why we were having serious communication issues. I was told it was the cRIO rebooting (and so tried a bunch of fixes to secure its power, which kept coming loose). Prior to one qualification match I found that the positive line to the cRIO has come out, and as we didn’t have a small-enough screwdriver with us, someone had to run and get one. This time, we got it done in time for the match. On the practice field at the end of the day, we find that the main comms issue (or possibly another) is that the dLink is rebooting, and that issue was fixed with a single ziptie :rolleyes:)
  • Saturday went really well, aside from heavy defense…

PS Why does this year seem to have more nightmares, even though we did better? It also seems to have more repairs than outright removals :D.

I guess we’ve been lucky to not have any disastrous on-field collisions/accidents. The worst repair I can remember us needing to do was during inspection in 2011. We drew quite possibly the harshest of the inspectors, and he proceeded to pick apart everything that he thought was wrong with our robot (the rounded corners were “too sharp” and had to be duct taped, every single wire connection was “too loose”, the chains were too loose or too tight). After close to fifteen minutes of this, one of our mentors, frustrated, went to tighten the (already carefully tightened both during build season and earlier that day) battery terminals on the PD Board - and the entire bolt snapped off.

Due to our design that year, our power distribution board was on the lowest level of the robot (on our drive base), and a second board with all of our pneumatics equipment was mounted directly above it.

Fortunately, we had an extra board with us, and it only took about 45 minutes to reach through the chains and transfer all the wires from the old board into the new board.

The broken board now sits in our shop as a reminder to all team members to never let that mentor tighten any part of the robot :slight_smile:

Look what little tidbit I stumbled across! 1712 Snapping their arm in 2008

Never realized my old team was out there that match also. :smiley:

That reminds me of a team we competed against in 2012 whose shooter broke off twice and still won the Quality Award. Funny how that happens.

The biggest nightmare repair I’ve been a part of was in 2011, we fried both our cRIO AND our 2 digital sidecars. Found out during the second and more extensive replacement session (included cRIO and multiple suspect wires) that we had pinched and shorted the connector between the two.
Missed a couple matches, still ended up 8-4 alliance captain #7. Lost in the first round. :confused:

Funniest repair (what?) was at Sweet Repeat in 2006, we popped a pneumatic front tire and had to replace it. Got the tire and axle on, but didn’t have time to put the second bolt through the aluminum pillow block, so we zip-tied it on.
On the field, after auto, we drive forward and stop, but the wheel keeps rolling forward. We then proceed to leave a trail of parts behind us for about 2 feet and eventually fall over for the rest of the match.

Gee… thanks. :rolleyes:

That brings back memories. I remember being in que for our Quarter Final matches when that happened. What’s so impressive about that match is 1712’s seemingly blatant disregard for the state of their claw. ‘Can’t hurdle trackballs? Better run laps’.

Memories indeed …
Yes the drive crew did a great job with the quick adjustment to run laps. There are people that still owe me the lunch I never got that day because of the lunchtime claw replacement…

Last qual match before alliance selections, we were essentially locked into our ranking before the match began, and just as I sit down in the stands to watch the match someone tells me, “We’re trying a new autonomous program for more points. We’re going to turn the corner.”

Knowing that the “new” auto program was most likely a glorified dead reckoning program (we never got the sensors or IR tweaked out the right way in that robot to “sense” for the corner), my response was, “WHAAAAAAAAT???”

“Don’t worry, Kressly. What could go wrong?”
Of course I’m thinking about penalties at minimum, or hitting our partners, or getting stuck, or damage…
“3, 2, 1…GO…”

If you look at the vid closely when the bot hits the wall, our human/hybrid player who put his hands on his head is the one who wrote that “improved program” and I’m happy to report we let him live and he’s finishing his degree at Ga Tech. He was given half the claw as a reminder to ALWAYS test his work before USING IT for real. The other half of the claw is still in the 1712 lab somewhere.

I never saw the end of that match…as soon as the bot hit the wall I grabbed alum mentor Zac Cohen (now leading FRC1111) and a few students and we immediately went to work prepping the spare* claw (which was nowhere near ready to mount) and continued to work through alliance selection and lunch, right up to field side at the start of QF1. There may still be pics and vid of that pit repair scene floating around somewhere.

Good find, and good times indeed.

  • and by “spare” I mean wood structure only, maybe the grip material was stapled on, but I doubt it. No motor, roller claw, bearings, aluminum reinforcement plates where the spring pins locked in, no wiring, no holes for the wiring to path correctly, no holes (about 30-40 of em) to get the claw within weight allowance. Yeah, it was complete surgery of the ugliest kind. The roller claw never ran in QF1-1. My heart rate was probably about 230 at the time and I couldn’t debug the wiring connection issue. So we ran laps and played a little ball keep away that match. Mike Williams found that issue and solved it prior to QF1-2, so 1712 was able to at least hurdle in the Quarters where we were eliminated by a strong #1 alliance led by FRC103 (how ironic is that?).

So there’s your story … Now, where’s my lunch??? :slight_smile:

That was one glorious pizza. Not my fault when the message to me was “here, take this pizza and go get your head ready for elims. No driving on an empty stomach. Don’t worry about the robot, it will get to the field ready for you.”

I took that as “Hey Chuck, we bought you a pizza. Go stuff your face before you have to drive against the #1 alliance.”

Don’t worry old man, I’ll get you your lunch. :wink:

At least that pizza was free…

2012 Israel Regional. We get to the venue early in the morning of practice day with high spirits, take our robot to the boxs, try and get it in, and oops, doesn’t fit. It was a tiny bit too wide.
Our drive had a KOP frame base, so what we did was take the outer c-channels out, cut their corners, and put them back in the opposite direction (with the open side pointing out) so the axle bolts’ heads won’t stick out.
Doesn’t sound like much but it took us the whole day to do, and made an already ugly bot a lot uglier…
No one’s proud of that year. Fortunately we compensated that this year when we bearly did any work on the robot :smiley:

You’re your father’s son, aren’t you :smiley:

This story has given me nightmares ever since it happened.

It was 2002 on Einstein, the last year at Disney. I was the field coach for 308 (The Monsters) back then and our alliance of 180 (SPAM) and 311 from Islip, NY made it out of our division after some rough matches.

Back in those days the matches were 2 vs 2, but the alliances had 3 robots. You had to play all three robots in each round in order to advance. The typical strategy was to have one robot be your anchor and the other two robots would swap. Our robot was the anchor of our alliance as we had the ability to quickly grab two of the goal and then lift them up to transfer the weight of each goal (at 180 lb each, if I remember correctly) to our robot. We could basically drive wherever we wanted once we had the goals lifted. We had a third arm to grab the last goal which would basically ensure us the win.

We were able to win the first round on Einstein in two straight matches agains a great alliance of 118 (Robonauts), 233 (Pink), and I want to say 144 (Who?), but I’m not sure about the third. It was on to the final round for the world championship!

The finals were set once 71 (The Beatty Beast), 173 (RAGE), and 66 (the Penguins back in those days) advanced in two straight in their semi-final. It was going to be epic. Team 71 seemed to be unbeatable, be we thought that we could lift the goals high enough to lift their robot’s file cards off the ground (one last trick up our sleeve that we haven’t shown yet). I couldn’t wait.

Then, the nightmare occurred.

One gear in the gearbox on the left side of our drive train started to shift so there was only about 50% of the face-width engaged, and we didn’t see it. The match started and we raced to the center of the field to meet 71 at the goals. A big collision occurred, and every tooth from the gear box in that reduction stage sheared off. We were useless as the left side of our drivetrain could transfer no torque. Needless to say, we lost that match.

In match two, SPAM and 311 went in while our pit crew tried to see if we could make a fix. In the 2nd match, SPAM and 71 had an even bigger collision at the center goal causing 71’s goal grappler to break. SPAM and 311 were able to manipulate the goals with enough authority to win match 2.

One match for all the marbles…

Our pit crew couldn’t replace the gear in time. However, since the gear had shifted to having 50% of the facewidth engaged, only 50% of each tooth sheared off (we were using aluminum gears to save weight). The pit crew pounded the shaft over so that the remaining teeth were engaged. The drivetrain ran, but I knew it wouldn’t stand up to another collision with 71. When it came time to pick who was going to play and 311 (our alliance captain) asked if we could go, I told him that 311 and 180 won the last match, they should try it again.

Then, the 2nd nightmare occurred: 71 took themself out of the match, leaving 66 and 173 to play. 66 had plenty of torque, but they were a single speed robot. We had a high gear (about 10 ft/s to race to the goals), and an ultra low gear (about 1.5 ft/s for push once we got the goals lifted). I KNEW we could be 66 to the goals, get them lifted, and the match would be over. I ran to 311 and told them we could go against 66, but it was too late. The referees said that we had already submitted our two robots to the match.

Needless to say, 173/71/66 won the match and I’ve never came that close to being on a world championship team.

I tried to convince myself that “maybe the half-sheard gearbox wouldn’t have even been able to drive.” When we finally got the robot home, we just had to set it on the field and see what might have been. The robot raced to the goals, lifted them, shifted to low, and was able to push them into another robot with no problem. Oh what might have been. I’ve been haunted by that ever since.

I have pictures of that gearbox that were taken immediately after that first match ended. I’ll have to see if I can find them.

Edit: I found the pics. Here’s one of them:

Well, yes. I challenge you to find someone who isn’t their fathers’ son. :rolleyes:

But I still remember being pleased we gave out enough of those fliers for Ed’s to give us a free pizza. Then Chuck went and devoured it before I got any…

A daughter? I digress…
this is a GREAT thread, and I LOVE Hibner’s story.

Thanks for the memories Chris. If you need a refresher try this link:

Storm Robotics Team, 2729 had to do a fair amount of repairs for faults during the 2013 competition season so far, all of which carry some good and simple lesson’s learned I think so I’ll share briefly. The issues are not nightmares like some of the others in the thread by any means. [This is turning out to be way longer than I intended, but hopefully serves a purpose to someone out there :)]

First, nearly all the issues are related to the ruggedness (or lack of) on our electrical system. In the 5 years of Storm we haven’t had issues like this. Luck be it, or possibly because we were defended on much more this year, we had several cRIO reboots, router reboots, etc.

At MAR Hatboro Horsham, at the end of the competition (last match) our cRIO ‘died’. 24V was verified but no LEDs came on when the bot was powered on. We had to pull the cRIO, bag it and give up. We later found that a single copper strand of wire, about 1/4 inch long had fallen into one of the cRIO module DB9 slots and lodged itself between a few of the pins, shorting them and the overall cRIO boot (would love to know the pinout of that DB9 connection to see how that is even possible). This was under the black DB9 cap which was installed. Our best guess is that the strand was sitting in the cap when it was installed. The cap had been vacuumed out once and then found in the shop vac, so possibly the strand stuck in the cap from static charge, was installed with the strand in it, and then the strand fell out later and lodged in the pins. Or it was sabotage. :slight_smile: But for GP’s sake we are going with bad luck :slight_smile: *

At the MAR Lenape regional we had a cRIO reboot early on which was traced in the pit later (after another luckily good match) to the 24V+ wire coming lose in the connector on the cRIO side. We tightened it best we could, hot glued it and continued on. Unfortunately later that day we had faults that looked similar, in another qual match and in the Finals Match 1. The Field folks said it was a router reboot.

After the competition we studied the DS logs and determined it to be a router reboot in both cases. Wiring seemed fine from the PDB through the regulator and to the bridge, but we noted to make it more rugged at MAR champs. After further log analysis we saw some deep voltage dips on the matches where the router rebooted. The best guess we came up with was bad connections on the batteries or bad batteries. The Good news - we keep battery logs during the competition to help ensure we use charged batteries and we can identify bad batteries. The Bad news - the log wasn’t kept after the competition, it never made it back to the school. :frowning: So we can’t prove which batteries caused the issue, but we checked and had 4 batteries with loose wires at the terminals. We replaced with better suited hardware and had no router reboots or cRIO reboots at MAR champs.
Note - we plan on posting the full log analysis on CD with screen shots when we have time to clean it up and will use them as a workshop later this year with electrical and software.]

  • The moral to this one is - keep (long term) your battery logs to identify problem batteries, check your wires often doing a visual spot check between matches, and whenever you think you have made your wiring ‘strong’ enough during build season, do some more! Inevitably something will fail when 120 lb robots collide, but you can prevent a lot of it. We learned that the hard way this year.

At the MAR championship we seem to have fixed our HH and Lenape issues, but instead saw some new ones. In QF Match 2 we took a not too memorable hit from an opponent, 224 in this case. You can see Electra (Storm’s robot name for 2013) roll away in a pitiful retreat, dead for the match. In the pit we found that the power pole between the PDB and the regulator unplugged. Surprising though as the hit was quite gentle compared to others survived this year.
-The moral to this one - even though power poles are strong - zip tie them or use the locking pins! A simple zip tie would have absolutely prevented that failure.

We had another failure at MAR champs, with only about 10 minutes to find and fix. After a match Electra had a bad “let the magic smoke out” smell. We ran through tests on every system and all were functioning without obvious issue. We continued to persistently search for a sign, and finally caught it when we saw a shiny corner (from melted plastic) on a Victor 884 that controls the drivetrain. We removed it and opened it up, and it turns out that the Victor FETs had self destructed horribly, but it was still functioning at a unit test in the pit. Interestingly the fan 12V wire looked like it had shorted to an FET. Not sure what happened first, the FET failures or the fan short (or maybe the short caused the failure).

  • The moral to this one - Don’t ignore your nose, I doubt a smell that bad can ever be a good sign. Study your robot until you find the source, nobody knows it better than you. Never be complacent or the failure will just pop up later.*