Mistakes

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

What’d you learn from it?

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

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. :stuck_out_tongue:
Also to pay a bit more attention to safety. It’s a good idea.

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.

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…

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:
http://technokats.org/gallery2/d/5015-2/fixing+the+arm2.jpg

Learning by failure is quite common.

Indeed, the more ways you fail, the more ways you know something doesn’t work.:slight_smile:

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.

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. :frowning:

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.

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. :smiley:

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.

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.

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.

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.

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.

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!!!

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.

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!

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.