Adaptive integral terminal sliding mode based trajectory tracking control of underwater glider

An adaptive non-singular integral terminal sliding mode control (ANITSMC) scheme is designed to control the position and attitude of the underwater glider (UG), considering the uncertainties of the dynamic model and unknown external disturbances. First, a kinematic controller based on a non-singular integral terminal sliding mode control (NITSMC) is designed to ensure that the trajectory tracking error converges to the neighborhood of zero in finite time. Then, a dynamic controller based on the NITSMC can make the tracking error of the reference velocity converge to the neighborhood of zero in finite time. An adaptive mechanism estimates the upper bound of the lumped disturbances. Moreover, a finite-time velocity observer is designed to assess the unavailable surge velocity of UG. Finally, through numerical simulation, it is verified that the ANITSMC scheme can achieve the desired trajectory tracking of the zigzag motion of the UG. Compared with the traditional proportional integral sliding mode control scheme, it is shown that the proposed method can have a better convergence rate and stronger robustness against lumped disturbances.