904-913This paper presents a robust control design using variable gain super twisting sliding mode control application in
Autonomous Underwater Glider (AUG). AUGs are known as underactuated systems and very nonlinear in nature make
difficult to control. The controller is designed for longitudinal plane of an AUG that tracks the pitching angle and net
buoyancy of a ballast pump for nominal system, system in existence of external disturbance and parameter variations in
hydrodynamic coefficients. The Lyapunov stability theorem has proved that the proposed control law is satisfied the
stability sufficient condition. The simulation results have shown that the proposed controller has improved the transient
response, reduced steady error and chattering effects in control input and sliding surface in all cases