Mistakes
 

Ever have a tiny, but devastating mistake occur while building, fixing, or playing with your robot?

What'd you learn from it?

Re: Mistakes
 

we were raising the robot on our lift cart and we werent paying attention and we busted an flourecsent light

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I was demoing a robot and one of the power distribution block's wires came out. I didn't know where it was supposed to go (and no electronics subteam members around), so I tried plugging it into a different slot.
Sparks. Lots of them. :ahh:
Luckily no harm was done whatsoever. I did learn that I probably wasn't a good fit for the electronics subteam. :p
Also to pay a bit more attention to safety. It's a good idea.

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Two, though no permanent / major damage was done.

First, I ran our robot backwards, full speed, into a pole in our courtyard at our school... this resulted in our battery holder flying off the robot. Who would only attach it with ONE screw? (Answer: our team.) Luckily, it did no real damage to either the robot or the pole and we got that problem fixed so it didn't happen in a real round.

Second, when we were first testing our arm, our coach told me to start raising it, I think... but I thought he told me to lower it. He got startled, since he was underneath it, and kind of backed away from it, tripped over a box, and ALMOST fell into a bunch of screw drivers and drill bits... We almost lost our coach! Luckily, nothing happened.

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Last week at Pascack Panda-Monium we needed to add a brace underneath our new hurdling device. We decided it would only take a few minutes and went to lunch first. We came back, assembled it, put it on the field...and it was assembled backwards...

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I believe it was the 2004 Great Lakes Regional when the TechnoKats made a minor modification to our robot that had huge consequences. That year was FIRST Frenzy. We made a rather ill attempt at a hook to lift our robot off the ground. It almost worked if I remember. However, we were trying to cut weight off for the elimination rounds, so we decided to take the hook off. Not realizing it was a rather load-bearing hook for our massive "claw" that year, the wrist of our gripper decided to break off in the middle of the match.

This was us trying to fix the arm:

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Learning by failure is quite common.

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Indeed, the more ways you fail, the more ways you know something doesn't work.:)

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I remember back in 2007, when I was on 269, we had problems at the Wisconsin Regional wherein our ramps would deploy in autonomous. We eventually go it fixed, but it killed our Friday.

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Last year at Great Lakes Regional we had a bug in our autonomous code (not surprising as I hadn't been able to test it) and needed to debug. I was the head programmer for my team, and I got to work.

I created a while loop that read sensor data and output them to screen continuously, and put it in the top of the autonomous program. I found the bug, but forgot to remove the test from the code, so all auton mode long our robot sat in debug mode. Thank goodness operator mode still worked. In forgetting to remove the test, I had cost myself and the rest of my team an entire autonomous mode's worth of operation.

The worst part though was when it happened again two matches later. :(

The blame totally fell on me, which was correct as it was definitely my responsibility to get the autonomous mode working. The experience was very disheartening at the time, but as a programmer it has taught me to think more about my code and what I am doing/have changed recently, and especially to learn from my mistakes in order to keep from repeating them.

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yeah our team had 2 mistakes over the past week, someone (we don't know who) zip-tied the wires on our forklift motors to the forklift so as it lifted it ripped them out damaging the motor so it had to be replaced.

To follow that up, I used too much solder on the connections for our new motor, so that it touched the motor, connecting our chassis to the electrical system, never a good thing. We have since removed the extra solder, and fixed those problems, but we all definitely learned some lessons from that.


And back in february we were practicing at Saint Francis HS when we left our tether cable in prior to the match, we chased it during autonomous, and managed to get it out before it did any damage.


It helps to learn from stuff like this. Though hopefully we can just learn from books, and other people's experiences from now on. :D

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Back in the day (2004), one of our team members had a great idea of building an 8 victor stack that looked like a christmas tree. Unfortunately one of the victors was wired in backwards and it took forever to diagnose the problem and it had to be the center victor that was the hardest to reach. Not something you want to do on the Thursday before a competition.

Or how about a battery that came loose in the crate (2003). We opened the crate and found a battery half melted down laying next to our robot. Amazingly enough it didn't leak or cause a fire!!

I think it is good to share these stories so that we all can be vigilant when it comes to safety and the importance of trying to do it right the first time so to avoid engineering mistakes. While making mistakes is a normal part of this process, how much we learn from them and from others will set engineers apart from tinkerers.

Re: Mistakes
 

All tools are powered by magic angry noise.

When tools make nice noises, they work great. However, anyone who has worked in a machine shop knows that as soon as you let the angry noises out of tooling, they automagically stop working.

So you can see where this is leading...

I hit a fixturing bolt with a 1/2" carbide end mill at 8000 rpm in a CNC machine once, which made a lot of angry noises as it exploded into thousands of pieces of shrapnel. It was not fun.

Re: Mistakes
 

I remember seeing that happen, I think we were even with you guys as an alliance once.

But oh man mistakes were do I begin, so many, so many.

Well one would have to be while I was showing others some of the basic electrical parts on a dummi board I had turned power on to demonstrate some stuff. Well I went to point something and when I went to point at something, I touched a PWM cable. Well that cable happened to be connected to the RC and the other end, well was plugged into nowhere. Well the metal leads on that touched the power source on a victor and there was a nice mushroom cloud of blue smoke.

Lesson learned. CHECK FOR Loose or unplugged wires BEFORE turning the robot ON!!!


That is only one out of many, I could go on forever but I won't, and I am sure others could do the same.

Re: Mistakes
 

Don't break the last blade to your bandsaw. It's a rough road from there....

Oh, another one that rookies and veterans should both take a lot of care to watch out for:
Don't forget to turn your robot on before the match!!!

I can't count how many matches we sat out because the driving crew forgot to check the switch. I've done it so many times.

Re: Mistakes
 

The most wonderful mistake of all:

We were in the eliminations this year (2008), and in the first round of the sem-finals, our robot just stopped moving.
I perosnally checked all electronics were ok, robot powered on, radio connected and everything, but the robot won't move.
So, I presumed that it was a radio connection problem, sinc USUALLY robots don't move when there is no radio connection.

So, I go on to check with the FMS guys, check what's up with thier systems, and they say it's all good. I tell them, "Our robot was OK!" and start arguing with him.

Later on, before the seconed round of the semi-final (oh, yeah, we lost the first round by 6 points) we got a timeout.
We used this time to check all robot systems.
I checked the power distribution, the gold thingy where power is given to the CIM victors (40 Amp) (I wasn't in the electrical team, but I'm familiar with how it works). I looked at the victors for a seconed before I touched some wires over there and I noticed the lights of the victor going on and off, and then soudnly it was solid orange, so everything was fine.

Seconed round starts, autonmous start.
A few seconeds of tention, and the robot soars to the first line. Me and the rest of the drivers cheer.

Teleop, 15 seconds to end.
Robot was working flawlessly with no problems, I was turning around the opposite side towards the opposing alliance's overhead to take out the ball they placed.
I stop the robot right underneath the ball so we can pop it out.

To my manipulator driver: "Ok, raise the arm!"
him: "I'm trying!!!"
announcer: "5,4,3,2,1 and times up!".

All the electrical wires going through the gold thingy got loose just as I stopped the robot, so all mechanisims (the arm and the drivetrain) didn't responed at all.
I only realised it wasn't the radio after the end of the day.

Moral:
Keep rolling (atleast in the game of Overdrive). :rolleyes:

Oh, yeah, we lost by 2 points. Soo....yeah....major bum.

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Test driving our robot and it hit a pillar and severely bent the forks in front. After this we added a new rule for our team: Don't let David Killoran drive the robot!!![

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Fail Faster, Learn More, Focus and Execute. Thursday, Friday, and Saturday mottos on Team Rush.

As far as personal failings, I cannot TELL you the number of times I have flipped logic in the code. I usually end up exclaiming, "Just do what I want you to do, not what I tell you to do! " Needless to say, I cant stand how long it takes to download.

Mechanical failings, put me near any tool, I will fail with it, I promise.

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i forgot about ths in my first post but always were saftey glasses around tools even if your not using them!!



i was making the diamond plate triangal corner gussets for our forks and i had to sand each three edges down on each one i think i did like 40 of them I had asked one of our mentors dave to show me an easier way to do it (on our combo bench and circular sander) and he took the triangle and started showing me and the sander sucked it out of his hands and shot it through the gap between the metal bench and the sandpaper and flung it out the other end VERY FAST!! We dident relieze what had happened untill i saw it fall out of the air and onto the floor 30 feet away

it had come about two inches from my face and the back of daves head!!


the moral- always pay attention if anyone is working even if you are very far away!

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The black wire on the PWM cable goes closest to the fan on the victor, plugging it in backwards ONCE will destroy the unit.... It took our team 2 years of random dead victors before we read the manual and obtained this key bit of information.
It really didn't help that our troubleshooting method before we obtained the manual was to plug the wire in the other way to make sure it wasn't backwards.

Another problem we had was one when the serial cable plugged into the radio on the robot came loose. The end plugged into robot controller was still secure. Somehow, the positive lead from the battery was also loose (after the main breaker). Someone went to turn on the robot and we had smoke everywhere. The battery grounded through the RC via the serial cable ground casing, causing the wire to heat up and burn the insulation.
Fortunately, no permanent damage other than the serial cable.

Re: Mistakes
 

1. During the build season, the programming team uploaded new code, and when we turned our bot on, the motors were Default all forward. Ran over a mentor. Luckily noone was hurt. We learned that the wheels should be raised when testing a new change ^.^

2.We spent about 3-4 hours, for 3 straight days trying to figure out why our robot wouldn't move. Turns out we were using 2 reciever boxes instead of 1 transmit 1 recieve >.<

Re: Mistakes
 

Oh yeah, a mistake was definitely letting me operate our robot's arm/elevator...for some incredibly odd reason, the cover wasn't on the electronics board, and I moved the joystick for the arm, intending to move it out of the starting configuration...
Wrong joystick. I accidentally moved the elevator down, and rammed the fingers of our manipulator into the mess of wires. We untangle them, and I try again...and do the same thing :eek: (I'm the reason the joysticks are now labeled)

And another thing...lathes and hacksaws don't mix. One of our mentors was using a hacksaw to trim something down on the lathe, the blade caught on the metal, and got totally bent into what resembled a lightning bolt. The he decided to do it again, and the same thing happened...I'm not sure why, but we handed him a brand new blade after that, and he managed to not break it (I don't even know why we let him have a second shot at it).
Moral of story: Hand tools should NOT meet machinery.

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Same thing, except not minor in any way. 2.5" carbide insert facemill spinning at 6,000 RPM straight down into the top of my vise at 1,000 inches/min.

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oooohh, any pics?

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I was driving the robot at a demonstration, and the Victors were in coast to make the driving a little smoother (we had really bad driving code that year, with no speed scaling whatsoever). It was heading a little fast towards us, so the other driver hit the E-stop. Unfortunately, E-stop wasn't wired to switch the Victors to brake mode, and it almost hit our table.
Lesson: while E-stop prevents you from moving the robot, it also prevents you from stopping it.

Also, during a test of a Victor, I supplied power to the wrong side, and blew out one direction. (it was unfused, but it probably would still have happened with a 40A fuse). EVERYTHING should be labeled and color-coded (nail polish works well. A dab of white on the fan blade also helps tell if it's moving or not).

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We installed a sonic sensor on the front of the robot to detect objects and stop before a major collision.

I believe I may have been the person who suggested that we have a student holding a piece of cardboard stand in front of it to make sure it was working.

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Ever see a CNC machine try to tap 2 inches of threads into a 1.75 deep hole?

:ahh:

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449's mistakes

-Leaving a flashlight in the drivetrain (Trenton)
-Removing programming cable while downloading, and assuring programmers that the light turned green (Cheaspeake)
-leaving critical sensors unarmored (Chespeake)
-designing easy-to-break armor for sensors in question (Chesapeake)
-cutting steel on a chopsaw with a light metal blade (no one was hurt, but the blade makes a great clock)
-making a chat system connecting the pit and the stands (freshmen...)
-scuff up floors at school
-scuff up ceiling!

Re: Mistakes
 

we had a couple of small metal shavings fall into the victor, it didnt move very far when we put the robot on the field.
The programing team also forgot to put an absoute value into the mecanum programing, That robot only went left, and later we decided to name it lefty

Re: Mistakes
 

????!!!!!

Explaination?

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We had this happen a couple times at RUSH, after spending 3 hrs trying to figure out what the error was (this is why you should always consult the manual FIRST kids) I had a nice long chat with one of the mechanical mentors about how he is never to drill without covering the brain again. I just reminded him that if he did it again we might not be so lucky and something could of been damaged.

Always the fault of the programming team eh? :p

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Always shave down the metal AWAY from the RC!!! And then we learned that its not always the programmers fault...

Also, 2 days ago at Cage Match in Indianapolis. Make sure you use a insulated tool when working on batteries. It turns out that the negative side which was taped up had been pulled out slightly, and i did not see the revealed wire. So the all metal multitool that i was using made contact with both polarities and sparks flew. Then i pulled the tool away from the battery. Only then did i realize how hot the tool had become. Now it has burn marks on the tool i was holding, and i could not feel my fingers while driving in the elimination round. In order to remind me, i think i may make shirts that say "Samir, don't electrocute yourself" with a pic of a body getting hit by a lightning bolt inside one of those red circles with a slash down the middle.

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I guess anyone at Silicon Valley in 2006 may remember this- our robot was doing really well, got picked by the Cheesy Poofs, and then in one after-lunch match, one of our wires connected with the battery and our robot literally burst into flame. Already one person on our team was running to the robot with a fire extinguisher, but luckily fire went out before extinguisher was necessary. Phlebas the Informer/Transformer was nicknamed Smoky Bear (our team name is M-A Bears, nicknamed Ma Bears in 2006).

Lesson- always recheck wires before quarters, semis or finals, because that's when Murphy's law really kicks into gear.

Oh yea, speaking of Murphy's Law, there was a time a mistake qualified as Epic Fail. Also in 2006, we were doing well at Cal Games when during the semis, every single ball bearing broke at the same time. We only found out when our robot began leaking little steel balls everywhere... and couldn't move.

Lesson- make sure your sizes are right! The whole season, summer and qualifying matches the spacers on the bearings were too big and ground into the bearings every time we moved. The final crash was just too much for said bearings.

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Murphy's law always kicks in at the worst times doesn't it?

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IRI was a real bummer this year. You guys broke your front forks, got it fixed in a miraculous 5 minute period, only to go out and find that a PWM cable had come loose. This past year was one of your best robots ever, and its a shame that it had to go out like that.

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I'll pass on the compliments, I don't work with RUSH that much anymore. You know that whole thing where the kick you out of high school for having accumulated too many credits? Yeah had that happen after the 2007 season. Let me tell you though, having the team I work with now (397) partner with RUSH at Kettering was possibly the highlight of my years in FIRST.

Story time from 397 now though, we were testing autons. In every auton the feather raises right at the start, well, we got tired of putting it back down manually so we pulled the power to it. The mistake? We never plugged it back in. And as anyone who has seen our machine can tell you, if the feather doesnt come up our entire machine is useless because the forks cant deploy. Which meant we were pretty well screwed that match.

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a few years ago at the Denver regional (rack and roll challenge) we made semi finals but our chain keept poping off, and we had no idea why. Our robot couldn't compete, and we may have won the regional if this had not have happened.... later, after the competition, we found a very very small 20 gauge (maybe) wire stuck in the gear box that was causing our gearbox to screw up and dechain our robot. (i don't even know how....?) It sucked..... :[

we learned that it was all electricals fault and that those jerks should keep their wires organized! lol. jk. the whole team learned the importance of being organized...

the sad part is that we still are not organized.

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Oh yeah, thats probably one of the most important parts of being in electrical, keeping it all organized and understandable.

That's why this year I'm laying schematics before we start.

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ya, seriously, you electrical people need to keep all your junk from the moving parts, i'm so sick of stuff like that happening!
lol. just kidding. XD

every year we make a schematic and it looks nice, but then we keep adding wires, we forget something, like a sensor that we added at the last minute (which never did end up wordking. lol) or something...

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Our lead electronics head last year was playing around with one of the circuit boards and somehow bridged two wires together and like the wires went crazy red and then melted like half of the board. No really bad injuries thank goodness, just a little cut on the finger.

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and that's why we have fuses.:D

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fuses..... why I hardly know the meaning of that word. lol. you mean a piece of tin foil crumpled up????

lol. :D

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No pennies, they fit nicely in the 40A fuse block.

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mistakes- how about your Robocoach making a perfect run and knocking down both track balls - and then suddenly realizing we are the OTHER color?

oops!!

WC :cool:

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really? awesome!
although with resetting fuses, they never go bad and there is no need for pennies.... lol


thats not a mistake, its called Gracious Professionalism.
ok, maybe it is a mistake. I just wanted to use my vocabulary. lol :D

Re: Mistakes
 

One time, when Brein was running the autonomous in our barn, he was trying to get the ball on the right side of the overhang in front of the red alliance. The autonomous started, all was going well. He then turned toward the right wall, and came a little too close to the wall and the side of the bot got caught on the wall, lifted the front and middle 4 wheels off the ground and completely bent the wall. :eek:
He then bent the wall back, and checked all the systems. All was good, so we tried to run the autonomous again. The robot started off, he turned it again towards the outside wall, and proceeded to lift the bot off the ground yet again. Bent the wall the same exact way he did before. :yikes: Once again, all was good, somehow.

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wait, a barn?

is that just the place where you test your robot or do you build it there too?


my team uses the student center in our school for testing. We use to test in the halls but the janitors told us we couldn't do it there anymore because we kept putting holes in the drywall and chipping the corners of the bricks. :D that was back when our driver was new. lol. well even when our driver was experienced it happened..... XD

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to call it a barn would be modest- it is a complete field in a robot wonderland


(jealous!)

WC

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Not as bad as making that same mistake but during regular match play, and that being the last match at nationals which we needed to win to finish in the top 20 and hoping for an alliance pick.

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I, for one, am perfect and therefore make no mistakes. Unless you count all the times that I completely screw up.

Seriously though, In 'Aim high' my team was a rookie. I was in charge of rules and had only read the "important" parts. Apparently, the parts you make the bot out of was an important part. Oops. We used illegal motors and had to completely redesign our robot at the event. Still had fun, but I learned to at least skim through the whole manual...if you don't have to actually read it.

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lol. ya. totally jealous. actually I kind of am.... our student center is small for practicing.... how ever, we could always do loops in the bus loops. lol.


of course we don't count that...... why would we?
Can I steal that form you? that is really funny.