Sensor systems for robotic applications under water

For applications of robots in industrial underwater environments sensor systems are required to identify the observed scene and to determine the position of the tool-center-point (TCP) of robots. A laser radar for guidance of a mobile underwater vehicle is based on a different absorption distance measurement method, which calculates the distance by the different attenuation behaviour of water at two different laserlight wavelengths. Therefore, scattering and attenuation processes in water have to be incorporated. An ultrasonic measurement system is built as a trilateration system. It consists of piezoactuators and uses a time-of-flight method combined with a phase-shift measurement. Thus it is possible to identify the exact position and orientation of the actuator of an underwater robot with a very high accuracy.