What is the strangest issue with a robot you have ever seen?
 

What is the strangest issue with a robot you have ever seen?

This can be either your robot or another team's, just the strangest issue you've ever seen. Bonus points if you tell us how it was solved.

Re: What is the strangest issue with a robot you have ever seen?
 

When we were working on our 2015 autonomous, our robot always seemed to go towards me, wherever I was standing, instead of going forward. We never really figured that one out.

Re: What is the strangest issue with a robot you have ever seen?
 

On the day before stop build, our RoboRio started acting up at a scrimmage. We had an intermittent loss of our USB camera, but the rest of the robot worked fine. We reflashed the RoboRio, and that appeared to solve the issue, and we bagged the robot the next day. Flash forward to SVR. We've just been selected for the playoffs, and the camera starts acting up again. We try frantically to reflash the RoboRio but to no avail. We keep getting errors. Somehow, right before we are set to queue before our first playoff match, the issue resolves itself. We didn't think much of it and were just happy the camera was working, and the robot went back in the bag for Champs. At Champs, the same issue started again, although this time we were too nervous to attempt flashing the RoboRio. Some matches the camera worked, some matches it didn't. We finally have two CSAs come over during lunch on Friday. They take a look, and confirm our worst fear: there is an intermittent short in the 5V rail on the RoboRio, causing the camera to work sometimes and then mysteriously fail. Cue us staying through lunch and taking the rear of the robot completely apart to replace the RoboRio. Luckily once the new one was in there was no further problems. The cause of the short turned out to be metal shavings from the build season finding their way into the USB port.

Lesson learned: Either use a vacuum or be REALLY careful when drilling near electronics.

Re: What is the strangest issue with a robot you have ever seen?
 

2016, SCRRF Spring Scrimmage. 4276 goes just about 100% on finding the portcullis in autonomous. They were aiming for the rock wall, which happened to be next to it. They did eventually get that mostly worked out... but it did crop up about once an event after that.


I've also heard of an E-stopped robot continuing to wander slowly across the field. (This was over 10 years ago.) Seems the batteries were surface charging, and the controller had enough voltage to drive the motors--slowly--but not enough to read an E-stop signal from the radio. :confused:

Re: What is the strangest issue with a robot you have ever seen?
 

I would be somewhat terrified to see an E-stopped robot still moving across the field.


Just after our Rookie season, we were demo-ing our robot at the main office building of our biggest sponsor along with two other teams. We were outside, and for some reason, did not have the robot cart for the driver's to set the laptop on to drive. So one person was holding the driver's laptop while the driver held the joystick in one hand and drove with the other. As the driver was turning all the way in one direction, the person holding the laptop accidentally hit the power button, setting the laptop to sleep. For some reason, instead of disabling the robot or ceasing input, the robot locked into the last signal it had received from the driver: turning in place at full speed.
Soon, the force from the robot spinning flung the battery out of the robot and sent it sliding against the concrete.

So, as any group of high schoolers would do, we brushed the battery off and zip-tied it back in. But as soon as the driver re-enabled the Driver Station, the robot immediately went back into its death spin and flung the battery out in exactly the same fashion. To this day, we don't drive the robot unless the laptop is firmly secured onto the cart or the Driver's Table, just like at a competition.

Re: What is the strangest issue with a robot you have ever seen?
 

We had an absolute encoder on an arm that would sometimes randomly read 180 degrees from where it actually is, causing the arm to ram down into the robot and stall the motor in an attempt to dig into the ground.

Our programmer solved it in software by ignoring the encoder value if it goes crazy.:]

Re: What is the strangest issue with a robot you have ever seen?
 

One of our drive team's accidentally flipped the robot crossing the drawbridge. During the match, one of our fellow alliance members tried flipping us back over. Well, that team ended up cracking our shooter's lexan completely in half. What can fix anything?.... DUCT TAPE! This surprisingly got us through 2 more competitions, including the MARC, an off season competition. The robot still works fine :)!

Re: What is the strangest issue with a robot you have ever seen?
 

We were going for audience reaction... I swear.

2011, Logomotion, my rookie year (mentor), and we could NOT get our robot to stand still during auto. We were using LabView, and even put a motor->off block into the auto code and it still would wander. We only attended one event that year, so for 9 matches we drifted during auto. Only once did that interfere with an alliance partner.

Re: What is the strangest issue with a robot you have ever seen?
 

At least you won't have to worry about that at Beach Blitz. :p


I've seen some magic smoke from robots this year, but the one that had me wondering was the rookie team who smoked their intake's BAG motor. Fortunately, a quick fix by replacing the motor... but smoking a BAG, used in its (at least generally) designed use? Takes talent.

Re: What is the strangest issue with a robot you have ever seen?
 

Well, this doesn't have to do with a FIRST robot, but it was certainly a strange issue... and the robot it was with was indirectly responsible for me becoming a mentor :).

Back in college, I took an autonomous robotics class. Basically, create a robot from Legos, motors, sensors, and a provided logic board to play a game involving searching for brightly colored plastic eggs and returning them to a nest. Got quite a ways into development of our robot, and were testing it out in the lab, along with several other groups.

Anyways, our robot was having some sort of programming issues... it was seemingly randomly going off-script and acting in ways that weren't actually possible according to static analysis of the code. We started adding in some print statements (there was a small display on the logic board allowing maybe a dozen characters to be displayed at a time). As we added more and more print statements to see what it was thinking, the behavior got worse and worse - literally the only changes were some print statements, yet it was going off-script faster and faster as we tested.

After a few days, we found out this was a bug with the display buffer on the logic board that the professor never bothered to tell anyone about - something about the way it worked behind the scenes caused the memory on the board to get corrupted if you tried to display an odd-length message. So with each print statement we added, there was a 50% chance it would corrupt the memory (as the message could have either an odd or even number of characters). We went through and "even-padded" every print statement (including the one that originally caused the problem) and the robot worked perfectly without any other modifications.

Re: What is the strangest issue with a robot you have ever seen?
 

https://www.chiefdelphi.com/forums/s...d.php?t=145297
I'm not sure whether to laugh or cry about the fact that out of 11 years of FRC, the 2016 season takes the cake for strangest issue to date.

Anyways, here's the short summary:

"Sirius" got in the habit of randomly spinning up various motors to top speed... while disabled.

The issue affected PWM and CAN-driven motors alike, and even happened several times while connected to the FMS. Since this kind of problem is pretty much the very definition of an "unsafe condition," we were disqualified from play for several qualifying matches in a row.

Re-seating the wires in question didn't appear to have any effect, and re-flashing the code didn't help either. Running low on options, we resorted to completely reformatting the RoboRIO; after that, we were no longer able to reproduce the unsafe behavior. The FTA eventually let us back onto the field, with the understanding that we would need to swap to a loaner RoboRIO if the problem ever happened again.

For my part, I was never completely satisfied with the hand-waving explanation of "something must have gotten corrupted;" seeing as the problem never recurred, however, all we've got left is hearsay.

Re: What is the strangest issue with a robot you have ever seen?
 

Not a robot problem, but I think it's still interesting.

Lone Star this year (I was FTAA). One robot refused to connect to the Driver Station, and the Driver Station refused to connect to FMS. As it was practice day, we were willing to take extra time and figure out what the issue was.

The first time this team come up to play, they had an odd configuration issue on the Driver Station laptop which seemed to preclude connection to the FMS. We sent CSA's with them after the match to help them do a clean install of the Driver Station on a new laptop and thought that was the end of it.

The second time they came to play, the same issue occurred on the new laptop (lack of FMS connection to the DS). Curious what the the issue was, we tried using one of the Spare Parts Classmates as the Driver Station as those are basically bare-bones installs and should always work. No dice. That Classmate worked fine as the DS for the two alliance members, but failed horribly for that team.

Fast forward 30 minutes, still no progress. We have re-run FMS pre-start at least 4 times; the 5 other robots come up fine, but this Driver Station and robot refuse to budge. The team is understandably panicking that they may not be able to compete at all. As a shot in the dark, I turn to the FTA and ask if the Field could be getting a 10.41.*.* IP address from the convention center. As it turns out, the field was getting a 10.41.255.* address with a subnet that conflicted with the 10.41.55.* addresses that the team needed to use.

5 minutes later, the problem is resolved and both of the teams laptops are working fine. The Field exterior IP address is usually checked during setup day for possible conflicts, but must have been missed for some reason. The team was extremely grateful for the resolution and was patient and helpful the entire time.

TL;DR: A 1 in ~650,000 chance that the FMS wants your IP as its IP.

Re: What is the strangest issue with a robot you have ever seen?
 

During out third match at FLR our robot switched out of the autonomous mode it was set in to another one which caused our robot to drive up onto to Portcullis and flip over instead of lifting open the Portcullis and driving through like it was supposed to.

Re: What is the strangest issue with a robot you have ever seen?
 

We had two very strange things happen this year. One was solved, one was not.

In one match at FIM Southfield our robot took off at full speed in reverse just before the start of the match. It seems to have happened at the exact moment it connected to the field. It never happened again and we have no idea why it happened.

At our second event in Livonia. Twice we suffered a complete reboot of the robot just after we cleared under the low bar. We spent hours going over every inch of our robot trying to find some sort of short. Then it happened a third time. This time we got lucky our press person was right next to it and saw what happened.

The polycarb sides on the field were not installed correctly. There was a small gap which allowed the side plate on the arm to get caught. The side plate for the arm was sloped and driving forward pushed the bot into the ground. This meant we could not free spin our wheels and would overload our drive motors going into full brownout.

Re: What is the strangest issue with a robot you have ever seen?
 

Our 2014 bot was a plunger shooter (single cocked back PVC tube with a plate on the end tensioned with elastic tubing) and we had some difficulties over the year stopping it, and the plate that was in charge of that duty broke multiple times, and a few resulted in the rest of the mechanism following the ball. There is nothing like shooting your ball at the goal, seeing it fly true, and seeing part of your robot right behind it.

Re: What is the strangest issue with a robot you have ever seen?
 

Back in 2009 when the new cRio control system had just come out, we were experimenting with it on one of our older robots to test out the new control system. This was back before Watchdog was a thing (or at least a thing that worked), so momentary signal losses would cause strange behaviors with robots. Consequently, our first attempt to drive the robot with the new system resulted in said bot driving full speed across our practice field and slamming into the cinder-block wall of the building.

Ironically, the robot was fine, the wall got a nice hole in it though (which is still there to this day). :ahh:::safety:::yikes:

Re: What is the strangest issue with a robot you have ever seen?
 

I was working a field at Buckeye for Aerial Assist. The giant ball comes flying across the field, 303 driver makes an amazing manuver to get the catch. Ball lands squarely on the off switch. Robot shut down instantly.

Re: What is the strangest issue with a robot you have ever seen?
 

Our issue was one that made absolutely no sense. Whenever our robot went under the low bar in autonomous while on the red alliance in Philomath, it would brownout for 60 seconds and completely take another robot on our alliance offline. This happened three times in a row. After that, they spent half an hour rebooting the field and it started working fine. Still don't know what happened

https://youtu.be/apulBWRFrQ4

Re: What is the strangest issue with a robot you have ever seen?
 

Our robot kept losing connection during our first couple matches at our first district event. The problem was every time we went over a defense our sponsor board would flex a bit and tapped our main breaker button just enough to reboot the radio....

Re: What is the strangest issue with a robot you have ever seen?
 

Oh god something like this happened to us at one of our events. Our method of mounting our top plate was a bit janky (we put it in the slot of some REV extrusion with some bolts on either end) and it sometimes fell out mid-match. We were in Q31 and Q37, meaning we had no time to fix the issue between matches. We had a proper mounting method in the works but the time it would have taken to put it on would have made us miss our next match. We went the match without the plate and forgot that our penumatic release valve was normally attached to this plate, meaning it was free-flopping. We went over the moat and got stuck. After a team member pushed us we went completely offline. Our driver checked it out and noticed that the button had been pushed JUST enough to put it offline. :/

Re: What is the strangest issue with a robot you have ever seen?
 

I can think of 2 pretty weird issues. The first one was my fault, we used an encoder with too many ticks per rev connected to a CIM. We had this feed into a jaguar for I think speed control, but I don't remember. When the CIM would spin up to full speed, the jaguar controller could not keep up with the interrupts and would lock up. Even disabling would not cause the motor to stop.

Another issue was at 2013 Bridgewater. I was in the pits as a CSA and the FTA radioed me that a team was hanging after a match, but half their drive train was still moving. Couldn't replicate in the pits but we did fine some swarf near the Victor's PWM pins, and that Victor did power the problem drive motor.

Re: What is the strangest issue with a robot you have ever seen?
 

Ok, this one is really weird.
So after the SFL regional (or at the regional, really) our shooter stopped holding position while getting ready to shoot, which would cause it to go up or down REALLY fast because of the force of the spinning shooter wheels (we have a U shaped shooter similar to 987). I couldn't figure out why this problem was happening as I was really busy with drive coaching at this event.
After World's (we didn't really look into this problem as we intended to do low goaling and defense at World's only), I looked over all of our code and found the issue: we had somehow deleted the lines of code that set the motor command to the output determined by our PID loop.
Now this is where is gets weird
By doing so, we actually ended up saving our robot... In that same code examination I realized that the other programmer, in an effort to make our code more concise, was now using the exact same variable for our shooter RPM goal and our angular Goal for the shooter. In other words, if we would have gone to position and then set the flywheels to our shooting speed, the goal (for BOTH!) would have been 3300 instead of the rpm's goal being 3330 and the angular goal being 80. If we had actually run the shooter like this, the shooter would have slammed down and ripped the robot's bellypan in half.
This mistake ended up being a good opportunity to teach others about testing code changes before deploying at least ;)

Re: What is the strangest issue with a robot you have ever seen?
 

I have a few:

1. Joysticks only moving one side of a tank drivetrain very slightly. Joysticks were swapped, their ports were changed, and a controller was used in place of the joysticks, but only one side would twitch forward or reverse. I'm not sure what happened or how it was fixed, but I think it may have been a programming issue. This was probably the strangest I have seen so far.

2. Loss of comms when the battery was a bit low, but still ~11 volts. The robot would just freeze, then it would reconnect to the DS, and driving a bit would disconnect again. A full battery would fix it until that was discharged to the same level. The motors didn't seem weaker when this happened(mecanum drive), so not sure what caused it. That same RoboRIO was used in another robot, and it did the same thing once, but with new code, a full battery, and(I think) an OpenMesh radio. Strangely, it didn't happen again, even a few times when the battery dropped below 10 volts.

Re: What is the strangest issue with a robot you have ever seen?
 

This year at the NYC regional we came in without much to do. The robot was in good working order after our week 0 and we did not have any planned upgrades. So, we got inspected quickly and proceeded to participate in some practice matches. After 2 practice matches we went to the pits and tried to shoot a boulder for a kid visiting our pit and well.... nothing worked. The robot would not inititialize and we kept getting weird errors. Nothing looked wrong anywhere and we had not changed anything since our last practice match. Turns out our programmer accidentally wrote a line of code (Not a programmer so sorry if I am saying this oddly) saying if the controller joysticks were not 0 to set all motor values to 0. He claims he never wrote the line but no one else would have. And... we will truly never know. My guess is we slightly damaged one of the joysticks so they were not completely 0ed and it broke everything....

4 hours of troubleshooting later
every CSA at the event later

We fixed it.

Re: What is the strangest issue with a robot you have ever seen?
 

On our 2015 robot, our driver would always complain the the left side of the robot would be slightly slower than the right. Throughout the entire season, we tried all different methods to track down the issue, and eventually came to live with it. At some point, a modification needed to me made that required taking of the entire left drive plate (a process far more difficult than it probably should have been) where we found that a nut had somehow gotten wedged in one of our wheels causing this https://drive.google.com/file/d/0B3d...5hRWE1Njg/view

If we had kept that up long enough we'd have been close to carving through the entire thing.

Re: What is the strangest issue with a robot you have ever seen?
 

still not sure what happend during the auto of this match. ourselves,COMETS, (3357), Average Joes (3620) and Code Red Robotics (2771) all had been having near flawless auton routines. then this match things went wonkie. any thoughts? our code skipped over 2 fail safes in the process and Joes said after the match that there was no feasible way for that to have occurred in auto.. as you can see the rest of the match everyone was functioning perfect on our alliance.

http://www.thebluealliance.com/match/2016miken_qm64

Re: What is the strangest issue with a robot you have ever seen?
 

In 2014, before this demo started, we were testing our robot to make sure everything worked fine. We were in a packed common area, and all of the sudden, the robot went in circles. E-stop didnt stop it. I ran and literally stopped it with all my force and hit the breaker off... This is why digital sidecars and metal shavings do NOT go out with each other.

Re: What is the strangest issue with a robot you have ever seen?
 

We were training drivers using the robot during the 2015 season and the robot kept getting a super high ping when it got fast enough... Every single time. And every time this happened, it was stuck in a state where it would turn the exact way to aim for a garbage bin and ram it. We broke a lot of bins that day. We figured out that the ping was simply due to an overloaded code but we didn't get why it was triggered with speed.

Re: What is the strangest issue with a robot you have ever seen?
 

At BattleCry@WPI this year we were in the finals (Thanks 166!) against 195, 2791, and 501. Finals match 2, everything was fine until about 30 seconds into the match when we drove over the rock wall. Comms and robot code dropped, comms came back, but we were stuck without robot code for the rest of the match which sadly led to our defeat. RSL was solid I believe. After the match, we checked our 5v rail and it was fine and once we power cycled the problem was resolved.

Needless to say, we replaced our rio for IRI.

Re: What is the strangest issue with a robot you have ever seen?
 

Sounds like a combination of loose power cables on the Rio and on the radio. Seems a bit excessive to replace the Rio...

Re: What is the strangest issue with a robot you have ever seen?
 

During one of our matches this year, we were the victim of a excessively hard autonomous. While our drivers caught the driver station, the lid on the laptop shut causing it to go to sleep. We ended up needing the FTA to bring over a spare driver station. After that we made sure that we disabled sleep mode on the driver station.

Re: What is the strangest issue with a robot you have ever seen?
 

One team at one of our competitions had a very forceful appendage on a long swinging arm with a small point on the end, designed for drawbridge and stuff. It ended up swinging down directly onto the power cord of our radio, ripping the tape off and yanking it out. Fun.

Re: What is the strangest issue with a robot you have ever seen?
 

We ended up switching to C++ because in 2014 we were running labview, and its CPU would randomly max out then the robot would crash and you would have to cycle the power.

Re: What is the strangest issue with a robot you have ever seen?
 

I had that too... Though if I clean my code it's fine.

Re: What is the strangest issue with a robot you have ever seen?
 

We had another programmer that knew labview and I told her she should let me try C++ and it fixed it. but yeah, Labview is the worst

Re: What is the strangest issue with a robot you have ever seen?
 

It may have been loose cables, but that was the first thing I checked when we got back to the pit. They all seemed fine. When we asked the FTA if he had any idea what happened, he didn't know. Better safe than sorry, really no harm in putting in a fresh rio after a season of 120+ matches.

Re: What is the strangest issue with a robot you have ever seen?
 

In the original firmware for the 2007 modem there was a bug that could cause robots to "hold last value" and not see the E-Stop. We had modified the AM Shifters of the time to include a 3rd higher gear, and were testing them out on the shop floor of the vocational school we worked in. We had noticed some weird behavior, but we were just playing around and most of the driving was being done by students without much practice so we kept playing around.

There was a nice long straight away, with the auto workshop at the far end. We were zooming down the straight away when the driver noticed the robot wasn't responding... he hit the E-Stop about halfway down the straightaway, and the robot didn't stop. It continued until the top of the electronics board collided with the undercarriage of a truck in the auto workshop a few seconds later. The universe definitely conspired against us on this one, as the Victors on the electronics board were exactly at the right height to be "the impact zone", and since it was our prototyping electronics board we had 10 Victors on that board -- all of which were destroyed.

Re: What is the strangest issue with a robot you have ever seen?
 

Does anyone remember the story of Harlem_Shake.vi?

Re: What is the strangest issue with a robot you have ever seen?
 

So last year, our lifting mechanism for the totes kept twitching up and down. This would happen whenever the bot was enabled, even when the controller wasn't connected. We calibrated the motor controller, but that didn't fix it. We went through the lifter code line by line and there was nothing there that could have caused the twitching. To this day, we still don't know what caused the twitching, but it doesn't matter because we cannibalized the control system for our 2016 bot :D.

Re: What is the strangest issue with a robot you have ever seen?
 

Not when it happened, but I have read about it through highlight posts. Two words: Price Less.

Re: What is the strangest issue with a robot you have ever seen?
 

We've semi consistently had issues with motors "jerking" while the robot disabled with no one touching the driver station. I've been told it's impossible but it has happened multiple times on multiple robots.

Re: What is the strangest issue with a robot you have ever seen?
 

In the build season of 2015, I had an interesting issue. We were testing an idea for a 6 wheel mecannum drive. It worked at first and then another programmer wanted to add PID loops. Lets just say when the RIO rebooted it ran full speed over my laptop. To this day my trusty laptop has some of its battle scars. (The screen and trackpad needed to be replaced, the frame of the laptop remains with gouges out of the aluminium.)

Re: What is the strangest issue with a robot you have ever seen?
 

For 2015 we were testing out our Auto and something happened and our robot started spazzing out and kept spinning around in circles, this only happened once and we don't know what really happened. Also with the same robot, sometimes when the arm mechanism is closed it starts twitching so we called it "hugging" now everytime it starts to twitch everyone says that all the robot wants is a hug.

Re: What is the strangest issue with a robot you have ever seen?
 

YOU'RE WELCOME!!!

Re: What is the strangest issue with a robot you have ever seen?
 

That time the e-stop completely malfunctioned and a robot broke out in auto to terrify the front row. The robot uprising has begun.

Re: What is the strangest issue with a robot you have ever seen?
 

We were at that one. Eventually something gets through all the safeties. The key is that it doesn't happen often.

We made an interesting discovery this year with our robot. It's a 6 wheel drive using pneumatic tires. With the right PID values, we can make it go sideways by rocking/bouncing forward and back. We should have some short video of this somewhere. We think it's probably killer on the WCD though.

Re: What is the strangest issue with a robot you have ever seen?
 

The strangest issue we had was at our Ann Arbor event when our robot kept flipping over. Our robot had never flipped before, even at our shop. We flipped 3 times in a row, in the playoffs. We didn't change anything from our first event besides take weight off our arm which actually should have made it less likely to tip. We ended up just adding a total of like 15 pounds to the front of our robot and we never tipped, we never even rocked anymore, we would just roll right over defenses and we level when we got off them.

Re: What is the strangest issue with a robot you have ever seen?
 

This year I saw two strange issues. One from my team and another from a nearby team.

First, a team in the sterling competition in michigan missed a decimal point in their coding for autonomous. When they started the match their bot went nearly full speed into the wall under the red alliance drive stations. The bot broke five welds on that side of the field.

Second, we had a catapult type arm that fed into our wheel shooter. Originally we thought of putting a hand type device on the end of the lever but in the end it turned out to be a plastic salad bowl. The plastic salad bowl actually worked better than a stainless steel on we got but it would need replacement every couple matches. FRC actually wrote in official documentation the term "salad bowl" which is cool.