I think having the ability to see what is going on underneath the water is just one of the most fascinating things we are able to do. Granted if somebody gave me the control of a Mars Rover I would be on that in a heartbeat. That is unlikely to happen and chances are pretty good that I won't ever make it onto another planet in my lifetime. So it's exploring what's in the oceans and lakes and being able to peer underwater is what really interests me. It's probably why I enjoyed scuba diving so much and why I am also intrigued by what a ROV can do. Since this discussion is related to adventures, I thought I would take this opportunity to put down in words what I plan to do with an OpenROV.
I live near Chicago, and while Lake Michigan would be a fascinating place to explore it's a bit out of my league (at least at this point). My plans are a bit more simple.
I have two very small lakes, actually one is a large retention pond, another a spring fed man-made lake which are walking distance from my house. I would be very happy if I could simply explore those. I understand the man-made lake was formed about 40+ years ago during construction of the neighborhood where a spring was hit and flooded the area. Rumor has it that a bunch of construction equipment (cranes, dozers, etc) couldn't be removed in time. They lie there at the bottom of what is said to be a 90-foot deep lake. There are a lot of nice houses there now and the lake is beautiful. I guess I want to see what exactly is down there. Residents keep the lake well stocked with fish, many which you don't see very much of around here and I am sure there are lots of fun things and fish to discover there.
Eventually I would like to build what I would best describe as a catamaran; something that would sort of tow the ROV around while I explore. I have read of similar plans by others so I might not be too far off here. The idea is to build a small somewhat stable surface structure (perhaps similar to a buoy) as a floating base station of sorts. The catamaran would be drivable like an RC boat, although I am considering perhaps a 2nd re-purposed OpenROV might due just as well, at least from the controls standpoint.
It would have a servo-surface camera, GPS, WI-FI access point, props, batteries and perhaps a solar charging panel. More importantly it would have a mechanism to let out or pull in a tether. But I don't need much. Maybe only 30-40 feet. The idea would be to drive around the catamaran with a ROV nearby underneath it. Remotely the ROV could be deployed around the catamaran. This just seems like it would be a lot of fun.
My goals would also include being on shore with a tablet and steer the catamaran out some distance, lower the ROV and switch to the ROV control and explore. GPS on the surface would provide approximate position of the ROV. Other surface sensors (temperature, wind speed) would provide data about surface weather conditions. Depth, temperature and other sensors on the ROV would provide information about what it looks like underneath the surface. I could collect the data and perhaps arrive at a complete map of the lake over time. Just for fun.
If it works out, I might even be able to extend the network to my house, tie it in to my home network and open it up for others to see and control remotely. Granted it's not a fascinating location, but it might be a really nice proving ground for this sort of thing since the environment is very forgiving. Even if I loose it, it isn't too far.
Anyway, in a nutshell these are my plans. Probably wont accomplish all of them, but I hope to accomplish some of them. Looking forward to receiving the OpenROV kit soon. It'll give me something to work on this winter when I am not shoveling snow.
Maybe you could use a float with a line ending in a noose. It could be attached to the ROV by a simple burnwire release. (A burnwire release is a light piece of wire that you connect to an electrical switch, so when you want it to break you put a little voltage on it and it quickly corrodes away. No moving parts!)
Another approach you could take would to not try and control the floating deployment barge. You already have propulsion in your ROV. If you where to use a continuous rotating servo you could use that attached to a spool to wind/unwind the tether to the ROV. If the ROV is 1" under the water with a tight tether it will take the barge with it wherever it goes. When you are ready to deploy you can spin out the tether via a Arduino board. You will need to come up with communications from the barge to land anyway so if you replace the Arduino with another Beagle Bone and use a wifi usb dongle on the Barge based BeagleBone you have your communications setup. your BeagleBone on the barge would - for all intents and purpose - be a barge based web serving router that would give you the link to the ROV and to your land based operations.
If you build the barge on some sort of sponsons that get the platform a bit off the water the ROV camera will give you the eyes you need as well.
I love this idea. I was watching the Robotboat kickstarter and dreaming about a catamaran rigged setup like this. http://www.kickstarter.com/projects/robotboat/robotboat-mark-vi
There is a guy in the community who owns a company making these types of low cost remote catamarans with payload potential. I'm KICKING myself now for not saving the link.
Thats very much the same idea I had in mind. I do have a readyset from http://fenixintl.com/products/readyset-solar-kit/ and an old wrt54-g which I like to use.
I like your idea and as Dan Myers pointed out the propulsion system in the ROV might be enough to control the floating boat but I'm afraid this might not work against high wind/sea currents. In this case I've thought of using a 'joystick' mechanism to guide a self propelled catamaran towards the ROV.
For this you might use an inverted joystick fixed onto the center of the catamaran, just above the water, with the tether attached to its tip. An onboard Arduino would then use the readings to swerve the catamaran towards the ROV as it moves about and vary its velocity according to the magnitude and direction of force on the joystick.
I guess the ability to auto let out or pull in the tether can also be achieved by adding a pressure sensor to the ROV in addition to the motor powered reel on the boat. Then again an algorithm on the Arduino could then take over by basing itself on the pressure sensor readings and the angle of pull on the joystick to calculate the depth of the ROV and use this to control the reel motors.
Those are just a few ideas I'd like to implement myself once I get my hands on this little beast;)