Cannot Connect to BlueROV2 Properly (BACKEND_OFFLINE)

General Discussion
1

Hi everyone,

I hope you’re all having a great summer.

I’m experiencing several issues with my BlueROV2, but the main problem right now is that I cannot connect to BlueOS properly. Before describing my issue, blew is my BlueROV info

System Information

  • Configuration: Heavy
  • BlueOS: 1.4.3
  • ArduSub: 4.5.7
  • Onboard Computer: Raspberry Pi 4B
  • Power Supply: Outland Technology Power Supply

Connected Devices

  • Ping Altimeter
  • Omniscan 450FS
  • Water Linked DVL-A50
  • Newton Subsea Gripper
  • 2 × Lumen Lights

Main Issue

I cannot reliably connect to http://192.168.2.2.

The BlueOS interface repeatedly disconnects and shows the BACKEND_OFFLINE error.

Interestingly, I can connect using:

​http://blueos-avahi.local/

However, when connected this way, most of my peripherals do not function correctly.

Specifically:

  • Ping Altimeter is not detected.
  • Omniscan 450FS is detected, but the Drive Test and Tap Test fails.
  • The DVL page never opens.
  • The BlueOS Network Speed Test also fails.
  • Overall, BlueOS appears to be only partially functional.

When Did This Start?

A few weeks ago, our BlueROV2 experienced a small water leak during operation (got leak warning).

I immediately recovered the vehicle and let it dry for about one week before powering it on again.

The first time I powered it up after drying, everything appeared to work normally.

However, after that first successful connection, the issues described above started appearing.

Previous Issues (Before the Leak)

Even before the leak, I had been experiencing several intermittent issues.

1. MAVLink Heartbeat Loss

Occasionally the vehicle would lose heartbeat communication.

I suspect this was also causing the DVL EKF to fail (EKF3 IMU0), resulting in:

  • Overestimated vehicle velocity
  • Large FOM (Figure of Merit) during dead reckoning

Has anyone experienced heartbeat loss causing DVL navigation issues?

2. Omniscan 450FS Doppler Mode

I have also been unable to use the Omniscan 450FS in Doppler mode.

Although Doppler mode is enabled in SonarView, the displayed data does not update correctly.

Instead, the sonar display remains fixed at the vehicle position, as if Doppler information is not being used.

EKF_IUM0_Error
EKF_IUM0_Error1920×1032 255 KB

Connection_with_192.168.2.2
Connection_with_192.168.2.21920×1080 305 KB

Connection_with_​avahi.local(4)
Connection_with_​avahi.local(4)1628×820 110 KB

Connection_with_​avahi.local(3)
Connection_with_​avahi.local(3)1647×902 72.1 KB

Connection_with_​avahi.local(2)
Connection_with_​avahi.local(2)1660×860 42.6 KB

Connection_with_​avahi.local(1)
Connection_with_​avahi.local(1)1919×924 196 KB

Any suggestions or troubleshooting advice would be greatly appreciated.

Thank you!

2

I have an update after doing some additional testing.

At one point, I was able to connect successfully via via http://192.168.2.2 and enter Cockpit. The lights, camera tilt, and video feed all worked normally.

However, as soon as I operated the gripper, the connection immediately dropped.

I then disconnected the gripper and tried reconnecting. After that, the BACKEND_OFFLINE issue kept repeating.

After waiting for a while, I tried connecting again, and this time it worked normally again.

The DVL was detected and functioning correctly.

However:

  • The Ping Altimeter is still never detected.
  • The Omniscan 450FS is detected initially, but both the Driver Test and Tap Test fail.
  • The Driver Test succeeded once, and the Tap Test briefly responded once, but after that they failed again.

Eventually, I also started experiencing repeated heartbeat loss again.

At this point, I suspect the issue may be related to the power, but I’m not sure. Since the connection dropped immediately after operating the gripper, I’m wondering if this could be related to a power issue.

Any advice or suggestions would be greatly appreciated.

Thank you.

3

Hi @dayhong -

Sorry to hear about your issues! Some thoughts -

  1. Have you tried the tether diagnostic extension? How long is your tether? It may help diagnose if your issues are related to a poor network connection.
  2. Do you see any signs of corrosion on any of the power connections to the Ping or Omniscan? A small leak can lead to corrosion and a bad connection - the inconsistent connection to those devices could indeed be a power issue…
  3. If you reach BlueOS via the IP address from its WiFi connection, is the connection more stable? You can find this IP address by clicking the wifi icon in the upper right, and then going to it in a browser on a computer that is connected to the same network.
  4. Unplugging all your peripherals to see if things are nominal is a good first step. Then, add each payload one by one and test to see if the performance changes. If it does, isolate with just that component connected to see if it is the root cause!

A leak of any size can cause havoc - a “small” water leak is relative. Would you say a few drops, a teaspoon, a cup of water made it into the enclosure?