Technical issues of underwater surveying in Urban rivers

Maritime Autonomous Surface Ships (MASS) are expected to be used in logistics, transportation, security, etc. in the future. When operating a ship, we have to pay attention to invisible objects under the water. Objects above the water surface can be detected by the camera system. On the other hand, underwater objects are generally detected by acoustic sensors called “sonar”. Almost all sonar products are expensive, so it is not realistic to mount them on all MASS. Therefore, surveying underwater with a survey ship and preparing charts that includes underwater objects, it realizes safe and reasonable navigation of MASS. Since mobility systems for tourism and transportation are required in urban areas, MASS is one of the solutions for those systems in urban rivers. However, it is difficult surveying in urban rivers. This paper describes some experimental results, technical issues, and the solution for underwater surveying of urban rivers, for which the demand for MASS is expected to increase in the future.