Weird disconnection/reset issue

Hello all,
My robot seems to be experiencing a weird issue where during driving it will suddenly reset/disconnect. When the disconnect happens, the lights continue to blink normally on the cortex and joystick (i.e. There is no slow flashing red light indicative of a disconnect), but the LCD indicates the program is restarting (it displays “Startup”). I think that it is not a loose battery or vex net key because those cause the slow flashing red light. However, I do know that the problem gets worse as battery gets low. Any ideas?

Edit: I am using one IME. Could that contribute to this?
Edit 2: I have already tried updating firmware on cortex and joystick, but that does not work. Also, could my RobotC version affect this (I am currently using 4.52 instead of 4.54)?

How old is your cortex maybe the connectors inside it that split and have become wider. Thats what happened to our cortex

We are experiencing the same problem. In the middle of the match our robot stops responding to Joystick input for a few seconds while the code still executes and all lights are normal.
We are also using IMEs and are using RobotC 4.54

The same exact thing happened to one of our teams around state finals. I’ll contact their team lead and see what the exact problem was, but I know it was really bizarre and tech support has almost nothing to say. I don’t know if you have the same problem, but if so I may be able to help. A temporary fix that they did was to reduce static charge to the cortex either by putting a sock on the robot or dragging a piece of metal on the field. (ground the bot) If either of these things help at all, you may have the same problem. How old is your cortex?

My cortex is ~3 years old. I am hoping that this problem is just a thing that happens only during driver practice; so far we have not experienced it in competition.

So the green lights on the controller and cortex stay on throughout the disconnect?

If it were me I would just look at all of the possibilities and test them one at a time (if you havent already)

So far I have tested battery disconnecting and disconnecting each vex net key, but both scenarios are different from what I am seeing.

We have experienced it in almost every match of our most recent competition. But have, as of now, failed to reproduce the problem when we are not in a competition (not connected to the match controller). Perhaps this could be an issue?

One thing that we haven’t tried is to isolate the vexnet key from the robot by using an extension cable, it is quite possible that interference from metal around the cortex is causing issues with vexnet.

One thing I noticed with the field is that I walked on it with shoes on for a brief period and built up a rather large static charge which has never happened before using the same clothing (uniform). Maybe something on the field is causing more static to build up this year?

Would a frame made of metal around the cortex be involved as that will interfere with the connection possibly

Are you using a backup battery? The symptoms could be a low voltage condition due to excess power draw. The Cortex switches off when the power drops too low, and then restarts automatically. Usually you can see this on the Cortex status lights, but you may not on the joystick.

I am using a backup battery. What you said seems reasonable, but the cortex lights do not seem to change during the reset. Rather, they act like the cortex is still connected.
If what you said is true, that would explain why the problem is more frequent at lower power levels.

Just a thought , but could the cortex be browning out? I believe (not very certain) that a brown out would cause the cortex to stall, until the voltage is restored to a better level. From my experience with FIRST, the roboRio micro controller has “Brownout Protection State”, where any outputs will be cut off as long as the supplied voltage is below a certain point, and they return to normal when a higher voltage is restored. The issue with this idea is that during a brown out, the Robot LED should have turned yellow. Along with this, the fact that the program itself restarts is strange, and I don’t think a brown out would do anything like that.

A similar problem was discussed in this thread, there may be some information in there that could help

Is there any noticeable change to the robot’s performance before it cuts out?

Ah, I have an update. Check for shorts everywhere you can. This was the problem with 9551C’s bot last year and they unfortunately didn’t catch it early enough and fried their cortex.