This degree dissertation is part of a project being carried out at the AI-Lab of the University of Zurich. The University of Zurich developed autonomous swimming robots that are able to detect obstacles and to avoid them. They are also able to swim in swarms. The problems associated with building and testing these robots confirmed the need for a new construction, a different method of achieving communication between the robots and a debug-interface, connecting the robots with a PC. The aims of the dissertation could thus be defined as:

• To build an under water communication system for the robots if possible based on inductive transmission. The robots should be able to transmit and decode at least two commands.
• The direction of the communication reception was to be determined.
• A wireless link between the robots and an external controlling station, a PC, that would allow the remote control of the robot had to be included. Furthermore, the robots should be able to communicate with a PC. This link is used to transmit debug data and to control the robot manually.
• A new construction was to be made.

All above mentioned goals were achieved.

The communication link to the PC was achieved with a Bluetooth interface.

The inter-robot communication was achieved with a magnetic field which in contrast to optical and ultrasonic communication displays the same properties above and below water. The source of received communications can be determined with an accuracy of 90? using the same antennas as for the data link. Two commands and associated behaviour have been implemented, "FOLLOW ME" and "GO AWAY" and can be demonstrated.

The newly developed hardware has interfaces to the original robot hardware using both SPI and RS232 interfaces.

The new robot is constructed as a swimming cylinder moving under the backstroke principle. It is powered by twelve NiMH rechargeable-batteries.