This project is in the very early stage of development. I've got a couple ideas that I want to explore and need a suitable platform to work with. The following are some of the components I hope to use to assemble this platform.
The objective of this project is to design a very small boat ( roughly 1 meter LOA ) that will be capable of autonomously traveling a preset survey grid to produce a sonar bottom scan. For this first iteration of the project I hope to use all off the shelf components, the only customization will be some custom code I will need to write.
HP Mini 311 - The brains of the boat. Probably over kill for the task, but I happen to have one.
Windows XP - Mostly because of the wide range of free tools and info available for it.
RoboRealm - This very cool software is really a key element to the whole system. It supports a wide variety of hardware (servo controllers, GPS sensors, serial interface, etc.) and provides a simple interface for making them work together.
Motor / Servo Control
Parallax USB Servo Controller - This will be used to control the boat's propulsion motor(s) and rudder(s).
GlobalSat BU-353 USB GPS - The GPS will be used primarily to provide position, course to steer and distance to waypoint. It will not be used for heading information as GPS heading is almost completely worthless at slow vessel speeds.
Silicon Labs USB tilt compensated compass - A very inexpensive, tilt compensated, USB interfaced compass that I just happen to have.
Polar View - A free chart viewer, route planning application. A track can be marked on a chart and then saved as an ASCII CSV file, which will then be used by the autopilot software I hope to write.
Remote monitoring / Control
Wifi + VNC - My plan is to use a 1 watt router connected to my shore based computer, and then a 1 watt USB dongle network adapter on the afloat computer. The goal will be to be able to monitor the boat's position and sensor data as well as being able to update/change the autopilot's route. I have no idea what the potential range is for Wifi over water, but hopefully 1 watt will give me at least a couple hundred meters.
I'm still sorting this out. I'd prefer to use something off the shelf (ie. a large RC boat) but most don't have the weight carrying and stability capabilities I will need. The hull will likely be a catamaran or trimaran and propulsion will be by electric motor. The final system will need to be hand carried by one person, so the size will likely stay at roughly 1 meter LOA.
I agree that it will be easier to debug in the boat. The actuator isn't that fast that I couldn't take control in the event that I needed to. Not much can happen at low to moderate speeds anyway.
Since I don't have the time to map the lake with any spatial resolution, I've been working on an autopilot for one of our boats. I'm using a Make Controller to interface with the Lowrance via serial, a linear actuator to control the tiller on an 8 Hp motor, and a very old boat. Obviously, safety is the most important part of the project, so it'll have some routines running to check the position and kill the motor if needed.
As a side note, I often wonder why I don't see more projects using the make controller. Just having the ability to write in C makes it worthwhile for me. Its obviously a bit big and heavy for a small aircraft, but for other vehicles I think it could be useful.
@Sgt Ric - This is just a test platform to experiment with. My last project was an underwater ROV that was rated to 250' depth, so I'm well aware of the affects of water on electronics. I may never put this first model in the water, but if I do it will go in a Pelican case or something equally water tight.
@Mogly - I've got the Parallax USB SSC and it's supported by RoboRealm so that's what I'll use. I also have a Pulolu Micro Serial Servo Controller which I might use later if I decide to go with RS232 instead of USB. I've used both in other projects and haven't had any issues with either one.
skip the PC and use an Ardupilot instead!
1. Much cheaper
2. Much easier for the integration of RC equipment and GPS
3. Less weight
4. An Ardupilot may survive beeing submerged, a PC definitely not :-)
5. The Arduino environment is very very easy to start up.
6. don´t know...