Super Twisting Sliding Mode Controller for a Diving Autopilot

This paper proposes a robust control technique based on Super Twisting Sliding Mode Controller for the depth control of an Autonomous Underwater Vehicle (AUV). The linearized diving subsystem of an AUV is modelled and a conventional Sliding Mode Controller was developed for depth control in turbulent marine environment. However, as conventional Sliding Mode Controller suffers from the drawback of chattering in the control input, a Super Twisting based Sliding Mode Controller for this particular application is being proposed for the first time. The proposed control algorithm satisfactorily eliminates chattering in control input. The robustness is verified against un-modelled system dynamics and external environmental dis-turbances. A time domain performance comparison between the proposed control algorithm and existing Proportional Derivative controller, Pole Placement State Feedback Controller and Sliding Mode Controller is done and the simulation results show the efficacy of the proposed control algorithm over others.