Hey @tony-white, we did a ton of hard diving over the weekend. About 25 dives/day at 100-150 feet deep. Water temperature ~85F. Air temperature ~90F. Cabin temperature ~75F.
I’m on the current version of BlueOS (updated everything last week). BlueROV Heavy with a Navigator AP and RPi 4. Stock camera and a Ping 360 installed (latest firmware)
We had about 6 instances of connectivity issues during dives this weekend. Either bad lag (1-3 second freezes in the video and telemetry feed) that continue for the entire dive, or a connection that dropped completely for about 10 seconds before the ROV reconnected. (The ROV would be disarmed when it awoke from these longer disconnections)
I noticed that our CPU temperature climbed to >70C degrees during dives. I started bringing the ROV into the air conditioned cabin on the boat between dives, but I still saw almost 80C a couple times if I left it running during short (5-10 minute) surface intervals.
I noticed that I had some really high CPU usage by a few processes a couple times when I checked. See below. Sometimes the percentages would jump even higher for a few seconds.
I am almost certain that our connectivity issues started when temperatures were high and the battery voltage had fallen to around 12.3V. After swapping in a fresh battery and letting the ROV rest for a few minutes in the air conditioning, the ROV was usually OK for a few dives. Only later would connection issues occur.
Question: Are these temperatures and CPU usages normal?
Hi @StrikeLines -
Sorry for the issue! That sort of performance doesn’t seem normal….
The process view in BlueOS doesn’t quite show the right cpu% - this is a known bug being addressed. You can get a more accurate idea of things by running htop in the terminal (may need to take the red-pill.)
If you could please download and share both a .BIN autopilot log from a dive you encountered issues on, as well as the BlueOS log files (from gear icon in lower left) then we could dig into what may be going wrong here.
Do you have any other accessories connected to the system, like sonars or other cameras? This is a clear acrylic main electronics enclosure? Can you share the specifications of your topside computer?
The USB camera can be more sensitive to high temperatures than the Raspberry Pi - so keeping the vehicle out of the sun and even in a tub of water when not in use can be necessary in hot climates like the one you’re operating in. Turning off the system when not in use also helps!
You may want to verify your tether isn’t causing issues by running a network test, and/or installing the tether diagnostics extension and verifying the available bandwidth (purple/blue line graph on upper right.)
Finally, if the resting voltage of your battery was only 12.3, you may have over-discharged it an permanently lost a bit of capacity - you really don’t want cell voltages to dip much below 3V, which corresponds to 12V, and when a 12.5V battery takes a strong load it may easily dip lower than that…. We recently updated the battery care guide with some detailed information if you’re curious -the discharge curve near the top really explains the issue graphically!
Hey @tony-white, my tether diagnostics results are posted here. I think it’s unlikely that my tether is the problem.
The ROV is in the clear tube. The Ping 360 and lumen lights are the only connected accessories.
The topside computer for this trip was a PC, i7 8core processor, 32GB RAM running BlueOS and Cockpit in the web browser. (I tried the desktop version but could not get it to recognize my controller.)
I’ll download and post the logs when the ROV gets back to the office in a couple of days.
What are normal CPU temps for the BlueROV during operation?
