Scanning Sonar Thoughts

[EliotBR (Eliot)]

I meant to respond to this a couple of days ago but must have closed the tab - my apologies.

@Rov36

I installed QGroundControl and the RasPi software with a few problems.
The download has to be from Blue Robotics.
I had to change my Ethernet IP to 192.168.2.1 or it will not work.

BlueROV users will generally follow the BlueROV2 software setup documentation, which provides the relevant download link for QGroundControl, and specifies the IP requirement. Given you’re not coming from that direction, it’s understandable that was a bit harder to find for yourself - if I’d thought of that I would have linked to those docs in one of my previous comments.

@Rov36

There is no indication that my Win10 computer was talking to the RasPi companion computer on the Ethernet cable because I had no camera or Pixhawk connected.
Pinging the RasPi worked to prove it was connected.

These make sense.

@Rov36

I used the Companion Webb Interface on http://192.168.2.2:2770/ and when I connected a webcam to the pi it showed as connected even though there was no video (my camera is not compatible).

The web interface is really useful for things like that - it displays any named screen sessions running on the RPi, as well as any detected devices

@Rov36

I’m starting to order parts for video and sonar. I am impressed with Youtubes I have watched. It would take years for me to design a system like those Sonar.

Cool! And yes, the Blue Robotics R&D and software teams have worked really hard to make the sonars low cost but still high performance and adaptable to different use cases

@Rov36

Question: Which raspberryPi 4 should I order for the surface computer? 2, 4, or 8GB?

More RAM lets you store more temporary data at any given point in time. For your use-case of streaming 1080p video and telemetry data I’d expect you can get away with 2GB, but I’m not sure how RAM-intensive Raspbian or QGroundControl are and unfortunately can’t test them right now (a quick test of PingViewer on my laptop had it using 150MB, so that’s not too big of an issue). Personally I’d err on the side of higher “just in case”/for future-proofing, but my expectation is you can likely get away with 2GB.

@Rov36

Question: There is an attitude instrument on the QGC screen. It only shows +/- 10 deg. My ROV can dive vertically so, assuming I can interface my PIC to the pi, can that be changed easily?

Assuming you’re talking about the pitch indication, I believe the numbers change as you tilt further. I’ll ask someone internally to confirm since I’m currently unable to test.

The attitude measurement will be sent up from the companion computer as a mavlink message, so assuming you can get the value from the PIC to the RPi then you should be able to set up a script using pymavlink to send the value up to the top. The mavlink part you can test without the sensor actually being connected - you can make a script that just cycles through values and sends them up as pitch messages, and see what happens on QGroundControl to the attitude display. This post should be helpful in getting a working mavlink connection between the companion computer and QGC. You’ll need to swap out the named_value_float message with an attitude message.