Blueprint Subsea Seatrac USBL Interface

BayDynamics · July 14, 2018, 3:22am

Hey Guys

I was wondering if anyone has used the Blueprint Subsea Seatrac USBL system with the BlueROV yet?

If not, im wondering what NMEA strings it would need to output to QGC in order for waypoint targeting to work? Im wanting to set target locations via the Seatrac software, which can output virtually any kind of data string, and have the BlueROV move to that location.

Any suggestions on the data interface into QGC please?

Matt

rperkins · July 15, 2018, 7:07pm

Hi Matt
I did some work recently to integrate info from a Subsonus USBL system from Advanced Navigation into a BR2/QGC setup. QGC can be used to set up all the waypoints you’d like, but to get this to work you’ll want to feed the vehicle’s position via NMEA data to the vehicle itself, specifically to some software that’s running on the Pi companion computer that will relay the info to the pixhawk. GGA, GLL or GNS messages will work. You can see the relevant companion code here:

github.com

bluerobotics/companion/blob/master/tools/nmea-receiver.py#L97


      
          if not datagram: # TCP disconnect
              print("Remote has hung up")
              sockit.shutdown(socket.SHUT_RDWR)
              sockit.close()
              sockit = waitConnection()
          else:
              for byte in datagram:
                  for msg in parser.next(byte):
                      if msg.sentence_type == 'GGA':
                          data['lat'] = msg.latitude * 1e7
                          data['lon'] = msg.longitude * 1e7
                          data['hdop'] = float(msg.horizontal_dil)
                          data['alt'] = float(msg.altitude)
                          data['satellites_visible'] = int(msg.num_sats)
                      elif msg.sentence_type == 'RMC':
                          data['lat'] = msg.latitude * 1e7
                          data['lon'] = msg.longitude * 1e7
                      elif msg.sentence_type == 'GLL':
                          data['lat'] = msg.latitude * 1e7
                          data['lon'] = msg.longitude * 1e7
                      elif msg.sentence_type == 'GNS':

So your surface Seatrac unit will want to be sending UDP data to the companion at 192.168.2.2:27000 or TCP info on port 27001, as shown here:

github.com

bluerobotics/companion/blob/master/tools/nmea-receiver.py#L9


      
          #!/usr/bin/python
          
          
import time
          import pynmea2
          import json
          import socket
          from os import system
          
          
# destination / output
          ip="127.0.0.1"
          portnum = 25100
          sockitOut = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
          sockitOut.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
          sockitOut.setblocking(False)
          
          
# UDP source
          sockitUdp = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
          sockitUdp.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
          sockitUdp.setblocking(False)

If I recall correctly, the Seatrac units don’t do NMEA data by default, or at least not UDP or TCP, just a serial output… in that case you’d need something to shift that data into NMEA output. I’ve looked into these units too, I’d really like to get one.

jwalser · July 16, 2018, 3:16pm

The autonomous functionality of ArduSub is still in development and is not stable.

rperkins · July 16, 2018, 5:24pm

I can attest to Jacob’s comment, vehicle behavior in position-enabled modes has been unpredictable-- often perfect, sometimes quite wacky.

BayDynamics · July 16, 2018, 9:46pm

Thanks for the info Richard

What kind of scenarios have you experienced where the sub has gotten “wacky”.
Where there common details that caused it?

Iv placed my order with Blueprint Subsea so now its time to get the interface sorted. Autonomous travel isnt critical but i guess ill be ready to use it once its stable enough.
How have you found your Subsonus system? Any feedback after using it in real life??

rperkins · July 18, 2018, 10:51pm

Hi Matt
The wacky behavior mainly shows up when entering a position-enabled mode or starting a programmed mission. Despite having a stable, accurate position from the subsonus system (or GPS antenna on a pole on my vehicle), sometimes when you enter one of these modes or start a mission the vehicle just takes off in the wrong direction and accelerates or starts descending rapidly. If you enter one of these modes or start a mission and things start out properly, I don’t think I’ve seen it go really wrong after that, which is good, but there’s no predicting which way it’s going to go when it starts.
The subsonus system is really nice. The user interface is a beautiful bit of design and the hardware works really well. There are frustrations, like some of the documentation could be better and some non-standard choices they made in their implementation of NMEA messaging are puzzling, but all in all it really works well. It would be even better if we didn’t already have a good AHRS on board our vehicles courtesy of the pixhawk. When their new “mini” transponders are available it’s going to be a really compelling system.

BayDynamics · July 18, 2018, 11:32pm

hmm … interesting about the automation initiation issues. I wonder what development is still to be done with it?
Im guessing its way down the BR list of things to do.

Im glad your Subsonus system is working for you. It looks like a really nice system. Im hoping when my Seatrac system from Blueprint Subsea arrives I dont have to many issues interfacing it. But without a stable release on the BR i guess ill just use it solely for tracking which will make life easier to start with i suppose untill the system is proven reliable.

BayDynamics · July 22, 2018, 11:36am

Hi Guys
Im wondering how im going to get the data from the surface unit into the Pi for position data.
If the topside USBL unit is connected to a COM port on the topside QGC computer and the Pi is on the BlueROV network surely i can send the pi the position data direct across the network?
I would have to look into this.

I dont have any wires on the tether to transmit it via serial direct.

Thoughts / suggestions?

jwalser · July 22, 2018, 3:37pm

Check it out:
https://www.ardusub.com/developers/gps-positioning.html

Eloi · May 13, 2019, 2:27pm

Hello,
Could anybody give some feedback on how they integrated the SeaTrac mechanically (and possibly power) onto the BlueROV2?
Thanks

Benji · May 14, 2019, 9:14am

Hello @Eloi,
I 3D-printed some holders, and am using the battery that came with the USBL, so no need for a penetrator, and you’ll still be able to locate it even if the ROV battery is dead / enclosure flooded etc. I use a little rope to secure it in case the 3D printed part breaks.

Some pictures:

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