A UUV needs to have a robust path following performance because of unpredicted current disturbances. Because the desired path of a UUV is usually designed by considering the locations of obstacles or geographical features of the operation region, the UUV should stay on the desired path to avoid damage or loss of the vehicle. However, conventional path following methods cannot deal with strong countercurrent disturbances. Thus, the UUV may deviate from the desired path. In order to avoid such

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... iation, a backward path following method is suggested. This paper proposes a path following method that combines pure pursuit guidance and nonlinear guidance for the UUV under an unpredicted strong ocean current. For a stable path following system, this paper suggests that the UUV adjust its heading to the current direction using the pure pursuit guidance method when the system is in an unstable region, or the UUV follows the desired path with nonlinear guidance. By combining the pure pursuit guidance and nonlinear guidance, it was possible to overcome the drawbacks of each path following method in the reverse path following case. The efficiency of the proposed method is shown through simulation results compared to those of the pure pursuit method and nonlinear guidance method.