June 2005 - How it all began

Idea: Inspired by projects such as an autonomous glider thats gets dropped from a weather baloon at 60,000ft I started thinking about a computer-controlled vehicle.

Basic options: Ground/Air/Sea. "Air" is not an option since I have no experience with planes and I figure this option has a high entry barrier. "Ground" is OK, but where in Germany can you really explore (without getting run over by a car)? So "sea" seems to be interesting: Münster has lakes and a canal, and both offer quite a bit of freedom (submarine, anymone?!).

Early draft: A submarine Decision: A boat or a submarine. I choose the boat for starters, since my model experience is zero. Since the computer is the focus, the ship should be reasonably easy to build. I'm thinking of a gravel lighter design which may lack charm but should be easy to build (square shape). Since propellers and rudders can be cought in mud and plants: how about a covered drive (directable jet?), and a bow propeller.

I'm not an electronics guru either. So the inital idea hovers around an ITX board, WLAN, car battery, and remote control via laptop/joystick.

Actuators? Luckily I stumbled across a USB-connected device which controls 16 or even 32 conventional model servos. Perfect! So: brushless engine for main drive, brushless controller, small engine for bow rudder (will this be good enough for easy maneuvering?), and another controller for that. Propellers operating in PVC tubing.

Will the ITX board consume too much power? An ITX board itself consumes about 25W under full load, and needs a power converter. Lead acid batteries are pretty heavy (not so bad with a ship). This does not include WLAN, harddisk and servo box. Option: Lower power embedded PC (problem: OS), or embedded controller like Basic Stamp. Problem in both cases: interfacing devices, nastly programming (C or even Basic).

What I have described so far is using a WLAN-connected computer as a fancy remote control, though transmitting data is very convenient (high bandwidth IP; good for web cam etc.). But I could connect my old GPS and buy an electronic compass to obtain information on position and orientation. This should allow for some autonomous operation (a plane has more tolerance to positioning, less tolerance to orientation; a ground vehicle has rather less tolerance to positioning, but dead reckoning is pretty accurate).

So what could the computer do? "Keep position". "Get me from A to B". "Avoid obstacles". Intelligent operation of servos.

I started to look for low power consumption PCs with Google, and came up with a number of PC104 boards, namely Micro886ULP. I later got a quote beyond $2000; I got the impression they don't want to deal with individuals. The other board is the IPC/NETIPC-5A by SYSLOGIC, but I did not follow up because I decided for an ITX board: full PC, no compromise, and should run for at least 2h on a moderately sized 12V battery (about 20W consumption).