Thanks, David, that's a very interesting idea.
We do see (via 2Can diagnostics page) the voltage dropping to around 7 amps at the same time the Amps jump to ~40 when the shutdowns occur - so this hypothesis is very plausible. I'll see if we can get an onboard voltage history made to monitor the minimum voltage on the VBus.
After reading your mail, I found elsewhere on ChiefDelphi a post saying that post-brownout, the Jaguar would need to be re-initialized for speed-mode to work again. That makes sense!
To seal the deal, some follow-up questions come to mind:
- Via BDC-Comm, after one of these events, we didn't see any other faults than the "comm" faults in the Jaguar. No indication of voltage faults (too bad, because this is the only indicator that makes me question the under-voltage brown-out hypothesis). In the case of a brown-out, what indication should we see via BDC-Comm? Or put another way, is there a deterministic way via on-board Jaguar logs to prove this is what's happening?
- How to best deal with this case, which is surely going to happen in tele-op mode during competition? After reading further on ChiefDelphi, I'm thinking of detecting the "possibility" we're in that state by exception-handling on commands to the motors. Thereafter, to poll the Jaguar's GetPowerCycled() state (which I assume should transition to TRUE after a reset completes), and if it does indicate the Jaguar was power cycled, to re-initialize it so speed mode works again. Does that sound like a good approach to you?
- Are you aware of any support for a "persistent configuration" (configurable startup defaults) in the Jaguar so that after reboot, in our case, it could enter speed mode automatically?
Thanks again for your valuable insight. I think this debugging process is inspiring to at least one of our senior students who is working on the software team.
- scott