Underwater GPS <-> DVL-A50 integration is most definitely coming. As you say, this integration will increase the total performance significantly. I don’t have an absolute schedule for this, but it is very high on our list of priorities!
Hi all,
We’ve bought a WL DVL; has the interface with the BlueROV2 been worked out yet ? We have a project we’d like to use it for in a couple of months, so keen to get it working.
Any advice appreciated !
Willian from Blue Robotics has been working on the DVL interface, which has reached a stage where it can be manually installed and tested. Last week our team at JM Robotics carried out a field test with the new interface, and it was very successful! If your project is in a few months it is very possible that the interface will be available by then, but I’d be happy to help you get your BlueROV running the experimental companion firmware beforehand if you’re interested.
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Hello @robins
I’d very much like that, if its possible. Is the interface depended on using a topside ?
For our project we need some sort of API to get the position/velocity
Perfect - will get in touch shortly
The interface runs on the companion, and is accessible through the Companion Web GUI. The interface itself receives inputs over TCP from WaterLinked’s Web GUI (documentation), so it may be easier to get the data directly from there. If you also need the vehicle’s position I believe you’ll have to instead parse mavlink messages, as the DVL only measures the vehicle altitude and relative velocities, which is later integrated by the EKF in Ardusub.
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Hi Kristian,
How did your DVL connect to ROV2 before?Serial or Ethernet?
Ethernet
Hi @wlkh
Can you confirm if the DVL can be integrated with the UGPS?
I see there were issues previously with the A50 sending an estimate of position to the EKF.
But is it now possible to take in velocity from the DVL and the positions from the UGPS?
Are there any guides on how to set up the DVL and UGPS?
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Hi @XYZEng ,
What I was referring to there was a separate solution from Water Linked that would merge the UGPS position together with the DVL position estimate. Unfortunately that solution has not materialized.
I haven’t seen anyone combining the DVL and UGPS position in the EKF of the BlueROV, but please let us know if anyone has gotten it working.
Hi Kristian,
Thanks for responding. I’ve spoken to others who are trying to fuse the velocities with usbl/lbl positioning.
Note @williangalvani is prototyping a lua script to more seamlessly switch from GPS positioning to DVL positioning which would make using waterlinked components much easier. It would allow you to acquire GPS at the surface before diving to the working depth.
I’m sure it could be adopted to take in UGPS values.
Ultimately Kalman filtered positioning incorporating DVL, Usbl/lbl and INS data would be the best solution. It’s what’s used on survey spec’d ROVs that have to maintain a very high degree of accuracy in the data string.
Ardupilot EKF (Kalman filter)
I don’t know whether or not the data can be fed into ardusubs inbuilt Kalman filter, on the surface it seems like it would work, but I’m sure there are obstacles. The fact that depth is used for altitude in the ardupilot ekf, or an issue arising from “number of satellites” data and how error varies with depth. But those are all guesses. A lot of people on here know more about this stuff than me.
Processed on topside
Kalman filtering is supposed to be quite doable in an external script ran on the topside unit (though not doable enough for my skill level).
Also data can be Kalman filtered “after the fact” so could potentially be developed and tested using logs.
I guess if waterlinked had a proprietary kalman filter that ran on the topside computer, you could send corrected data down to the ROV using NMEA injector.
It would encourage people who already own a DVL to get a UGPS and vise versa 
It would certainly encourage me for what that’s worth.
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