Depth control of remotely operated vehicles using nonsingular fast terminal sliding mode control method

Sliding mode control (SMC) method has been widely used in the trajectory tracking control of remotely operated underwater vehicles (ROVs), due to its great robustness against modeling uncertainties and external disturbances. But almost all the applications with SMC method in the control of ROVs are linear hyperplane-based, which means a large control gain is needed to accelerate the convergence speed and improve the tracking precision. However, a growing control gain may cause serious chattering and destroy the performance of the control system. To solve this problem, a new continuous nonsingular fast terminal sliding mode control (NFTSMC) method is proposed. Theoretical analysis and simulation results show that the proposed method can obtain faster convergence speed and stronger robustness compared with conventional continuous SMC method.