Gun Rae Cho et al.. “3D Space Trajectory Tracking of Underactuated AUVs using Back-Stepping Control and Time Delay Estimation⁎This research was supported by Institute of Civil Military Technology Cooperation(ICMTC) of Agency for Defense De-velopment(ADD), funded by Defense Acuisition Program Ad-ministration(DAPA) and Ministry of Trade, Industry and En-ergy(MOTIE)(Developement of multisensor fusion based AUVs terminal guidance and docking technology, 17-CM-RB-16)..” IFAC-PapersOnLine, vol. 54, no. 16, 2021, pp. 238–244. http://access.bl.uk/ark:/81055/vdc_100160116255.0x000003