Monthly archive - March 2013

Sonar mosaicing of chain scenario

After the first successful tests with the ARIS sonar, the UdG team worked towards reproduction of the chain scenario of PANDORA project. A chain of 13 links and a total length of about 7 meters has been built simulating a real mooring chain.

chain scenario

Reproduction of the chain scenario at UdG’s water tank.

Before the first year review of the project, we conducted some experiments inside the UdG water tank to simulate inspection of the chain by means of sonar.

Girona-500, equipped with ARIS, was manually teleoperated along the chain gathering images at a short range to generate afterwards an acoustic mosaic of high resolution.

The following video summarizes the mosaicing process of the sonar images:

The figure below shows the obtained full chain mosaic:

chain mosaic

Girona500 AUV performing a visual servo control

One of the demonstrations shown during the first year review was a visual servo control performed by Girona 500 AUV in front of a valve panel. This work has been carried out by the NTUA CSL group together with UdG. Three main algorithms work together to achieve this task: A visual detector identifies the valve panel and computes relative positions to it; an EKF-SLAM algorithm combines these updates with navigation sensor measurements to localize the vehicle while mapping the panel in the world. Finally, a control scheme navigates and stabilizes the vehicle in front of the detected target. The control scheme algorithm has been reported in a paper submitted at IROS 2013.