DISTURBANCE OBSERVER-BASED HIGHER ORDER SLIDING MODE CONTROL FOR DYNAMIC POSITIONING OF SHIP

Abstract

A dynamic positioning (DP) system is a computer-controlled system that automatically maintains a vessel's position and heading using its propulsion system, thrusters, and other devices. DP systems are also being extensively used during slow-speed movement and maneuvering marine crafts and sea-going vessels at high seas while carrying out very specific tasks which require a high level of precision and accuracy. The environmental disturbances in the form of wind, waves, and ocean currents are present and continually varying thus the vessel deviates from the desired track/position thereby hampering maritime operations. Therefore, to overcome the above-mentioned obstacles, a suitable control technique is required to maintain the heading and orientation of marine crafts and sea-going vessels. It is a well-known fact that PID controllers have a very strong presence in almost all domains of control application simply because of their modest structure, compatibility with analog and digital applications, and insurmountable record of success. However, in the application of a Dynamic Positioning (DP) System, the challenging part is to establish a decent tuning procedure for PID-based controllers.