We wanted to design a device which could carry out different research tasks fully autonomously under water. To control it we needed a computer which we could program. The nature of the task came from an assignment given by the Lego League for the “2005 Challenge: Ocean Odyssey”.

The idea was to construct a fish that would have some advantages over a submarine. Since our Robofisch has no propeller, it no longer endangers fish or swimmers, or churn ups sediment. And due to its fishlike appearance, it is camouflaged. It can take water samples at predetermined depths for subsequent lab analysis, measure the water’s depth via pressure sensors and its temperature and clarity via optical sensors, as well as do underwater photography. The RCX Lego computer used to control the robot was programmed with ROBOLAB software. The first functioning model we built had an engine, a hydroplane and a rudder for diving, and a device for taking water samples. So that the “fish” can tell when it has reached the bottom, we equipped it with wire whiskers and these act as sensors. Once the fish gets to the bottom, the whiskers “feel” it via a touch sensor and the program turns off the engine. Simultaneously it begins to collect water samples. As soon as it has the samples, the engine goes on again and the fish surfaces. Then the samples can be removed.