Sliding Mode Controller for Positioning of an Underwater Vehicle Subject to Disturbances and Time Delays

Unmanned underwater vehicles are crucial for deep-sea exploration and inspection without imposing any danger to human life due to the extreme environmental conditions. But, designing a robust controller that can cope with model uncertainties, external disturbances, and the time delays for such vehicles is a challenge. This paper implements a sliding mode position control algorithm with a time-delay estimation term to a remotely operated underwater vehicle to deal with disturbances, such as waves, and time delays. The controller is implemented on an underwater vehicle (BlueRov) and compared with a proportional-integral-derivative (PID) controller in a wave tank with different disturbances and when there exist delays within the communication channel. The
experimental results show that, the proposed control method provides signicantly better performance than the conventional PID in the presence of extreme disturbances.