Variable structure controller for longitudinal control of deep-submergence AUV

In the process of deep-submergence AUV changing depth, the error of small-perturbation linearization model is large, and the trajectory parameters change noticeably. Aiming at this problem, a variable structure controller (VSC) for the longitudinal control was proposed. The controller which is easy to realize consists of switching function and control algorithm. The motion of system in state space was analyzed, and the reachability of switching manifold and the stability of control were proved. To reduce the chattering, a modified controller was proposed. Based on Simulink, the AUV 6-DOF motion was simulated. The result shows that the AUV with modified VSC can chang depth fast, and its trajectory is smooth, which brings high performance.