Path re-planning method for an AUV to image rough terrain by on-site quality evaluation

Although autonomous underwater vehicles(AUVs) are suitable for seafloor imaging, it is currently difficult for them to evaluate the results on-site. Therefore the obtained image map often has unscanned areas caused by occlusions, disturbances, and so on. In order to improve the coverage of the map, operators have to plan a new path and then deploy the AUV again. This process is quite time-consuming and troublesome. The authors propose a new method for an AUV to obtain a full-coverage 3D image of rough unknown seafloor in a single deployment. Firstly the AUV observes the seafloor by following a pre-determined path. Secondly the AUV calculates the following on site based on the obtained data: 3D bathymetry map, unscanned areas on the map, and the next path which can be taken to image the unscanned areas effectively. Then, the AUV follows the new path to obtain better results. The performance of this method was verified by tank experiments using the AUV Tri-TON and its precision was evaluated.