Introduction to an AUV "r2D4" and its Kuroshima Knoll Survey Mission

In this paper, a newly developed AUV "r2D4" is introduced and its mission of surveying Kuroshima Knoll is addressed. As the successor of the AUV "R-One Robot", r2D4 was designed by IIS, the University of Tokyo, and constructed by MES, with the primary missions being the investigation of deep sea bottom and AUV intelligence. r2D4 is a highly reliable AUV with its length of 4.4 (m), demonstrating sufficient compactness as well as multifunctional capabilities and large maximum operating depth of 4000 (m). The first sea trial of r2D4 was carried out at Suruga Bay, July 2003. After the exploration off Sado Island in the Sea of Japan, r2D4 was deployed for the investigation of Kuroshima Knoll in December 2003. During Kuroshima mission, high quality acoustic images of seabed using interferometry sonar were obtained through the operation of r2D4, which could only be achieved by accurate and robust attitude control. The method of on-site position error correction was developed and testified during the Kuroshima Knoll mission. In this correction, based on the optimal estimation of SSBL position, regressions of actual vehicle trajectories are carried out to estimate the deviation between reference and actually formed way points. On the basis of the success in Kuroshima Knoll survey mission, r2D4 would be deployed in Mariana back-arc basin, toward the discovery of newly activated hydrothermal vents.