Design of a dynamic positioning system for a moored floating platform using QFT robust control

This paper describes the design of a dynamic positioning system for a moored floating platform by using robust control techniques, particularly Quantitative Feedback Theory (QFT). The goal is to minimize the drift resulting from the wave action by appropriate thrusters control. The model of the platform is a SIMO (single-input multiple-output) system, therefore an interesting question is that the plant has less degree of freedom for actuation and is difficult to control. The control problem of the underactuated system is solved by an iterative multi-stage sequential procedure. Simulation results are presented to demonstrate that the control achieves efficiently the dynamic positioning system. Therefore robust techniques based on QFT methodology constitute attractive alternatives in the application of positioning control of an underactuated marine system.