Robust Output-Feedback Control in a Dynamic Positioning System via High Order Sliding Modes: Theoretical Framework and Experimental Evaluation

Despite being an established and mature technology, Vessel Dynamic Positioning Systems are always in focus for the development of novel control applications in order to increase their operational capacities. Rapid and robust transient response without loss of control accuracy is, for instance, a requirement for autonomous operations. Standard technologies currently applied by the industry lack such properties. Emerging methods, such as nonlinear robust control techniques, may help to achieve this goal. This paper proposes using a Super-Twisting Controller, allied with a High Order Sliding Mode Observer to perform the Dynamic Positioning Task. This method provides the robustness of standard Sliding Modes Controllers while keeping accuracy and chattering suppression. A novel nonlinear sliding manifold and wave-frequency filtering is proposed for the Dynamic Positioning problem. The efficacy of this control structure is demonstrated in a series of experimental tests, whereby the subject vessel is controlled while disturbed by wave action.