After having build a few drones, (6 in total, but domestic pressures led to selling 3), and an autonomous Hexapod - one of my good friends has challenged me build something to explore the great harbour full of islands and reefs that sits on our doorstep.
This has led to a lot of research over recent months. There are of course lots of choices, but I’m continually drawn back to Blue Robotics.
I love the look of the T100/200 thrusters
The ROS package is another attraction. Having spent some time getting my head around ROS for my Hexapod, I'm keen to put that learning into practice with my next project.
The maneuverability of the ROV kit is impressive
Very tempting to leap straight into a project with the BlueROV. This seems good value given the cost of 6 T200's and ESC's is not far off the price of the full kit.
Two parts I’m still a little uncertain on are:
The best type of tether cable. I'm thinking industrial, stranded Cat5e.
The hardware for the controller. Probably Rpi2 and a PWM cape to control the ESC's and connect sensors.
For those who have gone before me, any words of wisdom or "watch-outs" gratefully received.
Look through the posts for cat5e discussions. Lot’s of opinions. I am actually using stranded cat5e for a tether on my project that now has several hours in the ocean and a lot of abuse. It is still holding up fine. I also ran actual strength tests. There is concern about the copper wire yielding, but I believe the PVC outer coating will prvent excessive yielding of the wire.
I found a post I’d missed earlier referring to Quabbin Wire 5710. This looks like a good option but way outside my budget for a full roll. Managed to find shorter lengths on Ebay though so might give that a try.
I’m glad you’re interested in diving into marine robotics
We’re going to be working on the ROS and APM code quite a bit in the next few months. Currently, the APM acts as an interface layer to connect the Raspberry Pi to the sensors and outputs. We’re going to be expanding the role of the APM to perform most of the low-level control of the ROV. The Raspberry Pi will continue to run ROS and will handle the more sophisticated functionality like integrating with more complicated sensors.
Happy to discuss or help with any other questions you might have.
Talking through the project with a few people here over the holidays has certainly generated a lot of interest.
My original thinking was to use an Adafruit PWM driver / Arduino combo to interface the RPi with the ESC’s and various sensors, using a modified version of the ros_arduino_bridge package.
But if the main ROS development path is expanding the use of the APM I may rethink that option.
I’ve got a couple of ROS related questions which I’ll flip over to a post on the ROS topic.
Keen to be involved in helping with development of the code and testing where I can assist.
