[ahartnet]

Hello,

This past weekend, we took our robot to a demo and found that we could not maintain a radio connection for very long. We did what we could there, but today we went back to the school to try to track down the issue, and I can not find anything that seems to reliably cause the issue. A run down of observations and attempted resolutions:

Observations:
1) Robot loses comm.
2) Can not recreate by wiggling wires, fuses, or components.
3) Only loses comm when driving. Doesn't even have to be up rockwall or moat. Sometimes it loses comm driving up the batter or over the ramp for the low bar. Sometimes it drives fine over the rockwall or moat and does not lose come.
4) If robot is enabled and we pick up and drop the robot from any "worst case" angles, robot still maintains comm
5) Robot does not lose comm if we manually push the robot over the moat/rockwall/back and forth on the batter
6) Robot does not lose comm from driving back and forth aggressively/full speed. Seems to have to be at an angle
7) Comm loss does not appear to come solely from a flakey radio. I watch almost all the lights on the rio turn off then on. RSL turns entirely off/dark.
8) No stuttering of robot motors - I do not believe that this is from brownouts (which rio logs support)
9) Robot does not need to encounter an aggressive hit for loss of comm. It's happened going up the ramp to the low bar at a slow speed.

Attempts to resolve:
1) trying to recreate loss of comm/rio power cycles by wiggling wires, shaking components, etc
2) Try to recreate loss of comm by lifting the end that goes over the moat/rockwall and dropping. Does not recreate loss of comm
3) Try to recreate loss of comm by shaking robot aggressively, no luck.
4) Replaced PDP (we tried using ferrules and I think the weidmuller terminals lost some of their effectiveness. We have since changed back to not using any ferrules
5) Replaced RIO
6) Replaced a potentially bad power cable from the switch to PDP
7) Replaced a potentially too short (insufficient strain relief) 18 awg wire from the PDP to the Rio.
8) Added ramprate for drive code. THe fact that this only seems to happen while being driven points me towards a current/programming issue
9) Replaced code with a very simple project that only drives with a ramprate
10) enable robot, wiggle one set of wires, disable robot, check rio logs, repeat with a different set of wires. I was hoping that maybe the rio logs would catch some quick disconnects that are quick enough that the rio maintains connection.
11) Wiggling wires above includes wiggling the 10 amp fuse on the PDP for the rio.

I've attached rio logs (I hope). I haven't encountered a problem like since the rio logs have come out, but I would suspect that the fact that I lose data about the voltages/currents/etc prior to the actual radio disconnect is suspicious. It made me wonder if the can bus cable could be bad. I'm fairly certain there has to be something in the power path to the rio that is the cause because it looks like the rio resets when we lose comm. Do the rio logs help point anyone to an issue?