A Time Delay Controller included terminal sliding mode and fuzzy gain tuning for Underwater Vehicle-Manipulator Systems

An improved Time Delay Control (TDC) method for an Underwater Vehicle-Manipulator System (UVMS) is proposed. The proposed controller consists of three terms: a time-delay-estimation term that cancels nonlinearities of the UVMS dynamics, a Terminal Sliding Mode (TSM) term that provides a fast response and a PID term that reduces the tracking error. In addition the proposed controller uses fuzzy rules to adaptively tune the gains of TDC and PID terms. A full dynamic of UVMS is presented and some simulation studies are done. Simulation results demonstrate the effectiveness of proposed method. The proposed controller not only provides the high performance in trajectory tracking, but it also has an acceptable robustness in presence of the external disturbance and unknown forces/torques in comparison with conventional sliding mode controller. •An improved robust Time Delay Controller (TDC) is designed.•PID-sliding mode controller for an 8 DOF underwater robot is used.•A fuzzy controller for gain tuning of sliding mode controller is designed.•The tracking error is reduced.•The speed of converging with respect to the conventional TDC is increased.