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

[aristochaotic]

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.

[ASD20]

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.

[frcguy]

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.

[EricH]

Originally Posted by ASD20

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.

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.

[Cothron Theiss]

Originally Posted by EricH

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.

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.

[Chak]

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.

[Mr.Twister]

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 !

[SenorZ]

Originally Posted by EricH

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.

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.

[EricH]

Originally Posted by SenorZ

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

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


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.

[Jon Stratis]

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.

[Ryan_Todd]

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.

[Aaron.Graeve]

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.

[Koko Ed]

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.

[Chris Mounts]

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.

[TogetherSword8]

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.