ARIS Forward-Looking Sonar: first tests

Last month the UdG team received a new piece of equipment for the PANDORA project: the ARIS Forward-Looking Sonar (FLS). This sonar generates high-resolution acoustic images at a near-video rate, and can play a key role on those underwater inspections where the water visibility does not allow the use of optical cameras. In the chain scenario of the PANDORA project, the process of cleaning the chain is prone to generate turbidity in the water which can difficult the algorithms taking control of the cleaning process itself as well as the subsequent inspection. By using a forward-looking sonar we plan to work with acoustic images and overcome this lack of visibility.
We have worked towards the development of an algorithm for the generation of acoustic mosaics and we have done some preliminar tests with the ARIS sonar in the water tank of the UdG. Although the sonar is still not integrated to Girona-500, it has been attached to the vehicle and we have used the ARIS commercial software to gather images of several small objects placed on the bottom of the water tank. The robot was driven in a zig-zag trajectory along three different tracklines gathering around 1500 different sonar frames. The developed mosaicing algorithm was able to register successfully a high number of frames, including many loop closures, achieving the consistent mosaic shown in the figure below.

Girona-500 with ARIS

Girona-500 with ARIS installed for the experiments.

Mosaic generated from ARIS frames

Mosaic generated from the ARIS frames.

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