With the availability of an improved IMU/Depth sensor, I have been doing some thinking and discussions with other members, namely @codewithpassion on how to improve ROV positioning, without having to look directly at the ROV. This gets more into the tele-robotics real that @Eric_Stackpole loves.I have also been watching a lot of the OpenROV videos on OpenExplorer and Youtube and have noticed that most dives are relatively shallow, but with some distance attached.
Anyway, @codewithpassion had an intermediate solution to put an independent GPS module on an OpenROV that could relay coordinates back to a base station while the ROV was on the surface. Obviously, once the ROV dove, you would lose GPS signal and you would have to rely on the compass. Even with that hindrance, this concept of knowing where you are while “surface swimming” is important enough that I think it warrants some R&D until @Jim_Trezzo’s system is fully up.
Let me illustrate:
- Suppose you have identified a shipwreck on multi-beam sonar data and want to go investigate.
- You over lay your data and then take your boat out to the site.
- Obviously, you don’t want to anchor on the site and damage it, so you anchor in shallower water.
- From here you deploy your ROV in the water.
- If you have a GPS module mounted on your ROV sending back positioning data to your laptop, you can see where the ROV is via what is known as a “Google Earth Bridge”. and your vessel and ROV position can be overlaid directly on the multi-beam layer you have made.
- Once you are directly over the site, you can engage the vertical thruster and drop down directly on top of the wreck site.
- Even if the currents push you a bit, you at least have a general idea where you are or you can use the compass to keep a constant heading toward the site.
I have given the “Independent GPS” option some thought and found a pretty good set-up that would work for my purposes: GPS to Google Earth using Arduino
Even though it is wireless, it would have limited range and be pretty bulky. I could fit it atop my “beast” as @Scott_W calls it and waterproof it, but it wouldn’t fit on a stock OpenROV.
But alas, we have a small computer onboad! I’m no programmer, but would it be possible to split the I2C and integrate a GPS module for surface navigation with an I2C GPS module? The NMEA 0183 positioning data could be sent via the tether instead of wirelessly.
The NMEA 0183 data could then be read via a separate port (like how :8090 is used for the video streamer) and then uploaded to Google Earth to show position in real time in another window.
It might be too much work for what it’s worth, but it would be nice to see where the ROV is in relation to the bathymetry.