Underwater glider trajectory control based on virtual hinges of multi-body model

Due to the influence of ocean currents, it is difficult to make the heading angle of underwater glider (UG) converge towards the course angle, resulting in a large distance error from the surfacing locations to the target location or path. To reduce the error, this study establishes the multi-body model of a UG and the target location. The two-dimensional (2D) and three-dimensional (3D) models are established and verified by simulation study, and the 3D model shows a smaller error in station keeping against currents. The 2D and 3D models for station keeping are tested in the sea trial of 2020, and the average errors of 3D model, 2D model, and the regular method are about 2 km, 3 km and 4 km, respectively. The results show that the 3D model is the most practical. Based on the 3D model, the target path is expanded into a channel for path tracking to avoid frequent course direction adjustments. In the sea trial of 2021, the average errors of 3D model and the regular control method are about 1 km and 2.5 km, respectively, which proves that the proposed 3D model can enhance the travel efficiency and the path tracking of UGs.