Weird failures


So twice this past weekend we had weird failures.

One was that the right side of our robot failed to move, at all (fortunately this was in our pit during a pre-check for a match) – the talons had power but were not changing state at all.

The other was that a joystick failed during a match–we had neither motor control with the stick, nor pneumatic control with the buttons, so it wasn’t a PCM or Talon glitch; it could have been both simultaneously, but that seems unlikely.

Logs showed no errors in either case.

Both of these glitches were fixed by closing and then reopening the Driver’s Station.

Any ideas? We’d rather this not happen at FLR this week.

Thanks, all!


Something similar happened to us during our first match at Montreal. The driver had complete control, but the operator controls were completely nonfunctional. Turns out, the operator controls had become unplugged/no longer recognized by the USB hub inside the controls…

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In Q26 at Palmetto, we had a “Weird” issue that never arose again. After sandstorm, our robot was fine, we go over and score in the ship, but after, our robot stops, we had no control, and then it started spinning in place, then drove around the ship and hit our partner 4075, drives around a bit more then stops for the rest of the match. The drivers were hands off after they realized it wasn’t them driving the robot.

Still not sure of the cause. I’m wondering if had to do with a low battery on the driver station laptop.


Not sure if it counts but the Wildstang incident at Midwest before Finals 2 was definitely a thing to see. And to be apart of.


Did you check the joystick section of the driver station before closing it? Was the joystick still in the right spot? Did the driver station still read the input values?


In our case, the joysticks still showed they were in the right spots and were functioning, just not controlling the robot


On the failure where we weren’t in “MUST WIN GO GO GO!” mode, the driver station looked normal, with the joysticks registering in the right spot. On the other situation, no, we didn’t do anything but near-panic try to get it working again.


Sounds like an intermediate short that is disrupting your CAN chain. This usually persists until a power cycle. My team had an issue similar to this on two counts: One was potentially due to how one of our talons was wired to on our carriage apart from the rest of the Talons (Multiple chained CAN wire having multiple potential points of failure), and a second due to an Arduino’s bottom touching our robot frame. For the talon, we split it off using a CAN bus splitter so it doesn’t take out half of our robot if it fails. The second we just put electrical tape at the bottom of the Arduino to stop it from shorting. The root of this was if it’s power connector which is connected to the VRM, touches the frame, you get CAN issues. So I would double check any power connections out of your VRM as well.


How would a short be solved by closing and reopening the Driver Station?


Loosing control of half of your robot is often time attributed to shorts due to bad CAN wiring/shorts.

The other suggestions related to bad joysticks USB have already been suggested, so I was offering another potential cause.


Maybe try to re-scan the joysticks next time? sometimes if one gets jostle and temporarily get loose it can loose connection with the drivers station. to fix it you can do as you did, restarting the drivers station, or re-scanning the joysticks… I hope this helps!


Our first two matches at Haymarket we had our operator controller cut out during the match and not coming back w/o restarting the driver station. After switching to a spare drive controller and remapping the buttons everything worked fine. Also this climb was great, it was impossible for the drive team to figure out what was going on too.

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I think I saw something similar this weekend in the pit of a team I was inspecting. They had three apparently unrelated problems. One of the students unplugged and replaced the USB plug for the joystick, disabled and re-enabled, and the problems went away, at least for a while; it appeared that he’d seen the issue before.


Thanks, all. We’re quite certain that our CAN wiring is secure and not shorted anywhere, but we’ll double-check anyway.


Did you ever resolve this? Somehow I stumbled on this thread again and come to think of it we had some similar failures at SF. Which controller are you using? Did you happen to look at the joystick values in the driver station? In our case we thought the issue was our Logitech controller changing input modes due to the switch on the back. Sorry to necro this issue but was wondering if this could shed some light.


Although it wasn’t a true failure we had to replace it


I see a very critical piece of plastic that sheared off due to fatigue. I’ll call that a failed part, and a failure mode I’ve never seen before.


In Qual 37 at NC DCMP, someone zip-tied our elevator carriage wires to the arm. Since the drivers had no idea, when they flipped to the other side, the entire intake mechanism disconnected. Our cargo intake was rendered useless that match.


Get on my level. I hate the cargo ship…

This happened in elims…


On the one hand, thank you for putting the breaker in a spot that is easy for my colleagues to get to. On the other hand, HOLY CRAP! I can now not say that I’ve seen the inside of an FRC breaker again.