Board Computer for Model Boat
When we (me and my brother, Rico) were young we built small model boats. While my interests tended more to computer hardware my brother stayed at this area. Finally, it was only a natural conclusion to make a combination of both things.
What is the job of such a board computer?
The model boat for which this system was developed for was (or is) a two-engine boat with two 7.5ccm combustion motors. These motors are basically independent and drive two independent propellors. Both motors are equipped with electric starter motors controllable via the remote control. This allows to restart the motors without the need to touch the boat.
The most interesting jobs initially planned to be performed by the computer are:
The picture below shows the core processor board.
It is made completely by hand - especially making the vias was a terrible soldering job ...
The formfactor of the board is a little bit strange because it had to fit into the bow-section of the boat.
The following components can be seen there:
The large connector at the right side contains a lot of I/O lines that are connected to other supplemental boards.
The smaller connector is used to control an alphanumeric LC Display (LTN211, 2 lines each 16 characters).
I wrote a small realtime operating system for this computer. This OS is able to handle several pseudo-concurrent operations and the I/O system (maily the LC Display handling). The OS I used in my DAT Recorder is based on this Operating System but has got a lot of improvements.
Status (What is really working?)
Three major functions are implemented for now:
The most interesting functions such as engine syncronization and tuning were never implemented. There are several reasons for this.
One problem was the reliability of the combustion engines. At that time we built this boat we had not that much money to buy very expensive engines. I don't know the situation today, but one should invest about 250 - 500 Euros in a good model combustion engine. Because the engines we used made a lot of troubles it was sometimes very difficult to get both engines running in a well state to make some tests.
Another problem was the reliability of the board computer itself. Although this is not completely true. The computer itself is running very well under laboratory conditions. But the electrical system of the boat caused sometimes system crashes. This is because I made the mistake to not make an optical isolation of the computer from other peripheral devices. So especially the starting process of the main engines often led into a crash of the computer because of heavy electrical bus instabilities (and there was nothing like a watch dog timer ...). Even a separate computer power supply has brought no major advantages. There's still a common ground and the computer controls more or less directly some servos and relais.
Since around 1995 this project is standing still and it is unclear whether it will be continued. There are several ideas in my mind for improvement of a lot of things and there's enough money available to invest in very good combustion engines and a new professional hardware. Also I collected a lot of experience in hardware design meanwhile. However, there are a lot of other projects and time is the problem. Also my brother is working on a real sailing yacht now rather than on model ships.
Today one would choose a microcontroller or DSP with lots of things integrated rather than building such a system out of "discrete" components.
For questions and comments send your emails to Mario.Trams@digital-force.net