Ultrasound sensors transmit sound waves in a high frequency range towards their target object, which reflect the sound waves as an echo. The sensors receive these signals and are able to calculate the distance using the time interval until the echo is returned. Distances can be measured and one’s own position can be determined using this measuring principle.

The underwater robot BionicFinWave with its undulating fin motion uses the technology to swim collision-free through a transparent pipe system. Five ultrasound sensors on its head and the inertial sensor technology constantly measure the distances to the walls and its actual direction through the water. A processor analyses this data and uses it to work out when there is a curve in the pipe system. It controls the fins in such a way that the BionicFinWave swims as centrally as possible and does not hit the walls.