Abstract
A dynamic positioning (DP) system is a computer-controlled system which maintains the positioning and heading of ship by means of active thrust. A DP system consist of sensors, observer, controller and thrust allocation algorithm. The purpose of this paper is to investigate the performance of proportional derivative type fuzzy controller with Mamdani interface scheme for dynamic positioning of an oceanographic research vessel (ORV) by numerical simulation. Nonlinear passive observer is used to filter the noise from the position and orientation. A nonlinear mathematical model of the ORV is subjected to the wave disturbance ranging from calm to phenomenal sea. Robustness and efficiency of the fuzzy logic controller is analysed in comparison with the multivariable proportional integral derivative (PID) and the linear quadratic regulator (LQR) controller. A simplified constrained linear quadratic algorithm is used for thrust allocation. The frequency response of the closed loop system with different controllers is analysed using the bode plot. The stability of controller is established using the Lyapunov criteria.
Highlights
The foundation of Dynamic Positioning (DP) can be traced to 1930’s where decoupled control for surge, sway and yaw were used
The purpose of this paper is to investigate the performance of proportional derivative type fuzzy controller with Mamdani interface scheme for dynamic positioning of an oceanographic research vessel (ORV) by numerical simulation
Robustness and efficiency of the fuzzy logic controller is analysed in comparison with the multivariable proportional integral derivative (PID) and the linear quadratic regulator (LQR) controller
Summary
The foundation of Dynamic Positioning (DP) can be traced to 1930’s where decoupled control for surge, sway and yaw were used. Application of the acceleration feedback based PID controller can be found in [10, 22] This was first instance of use of Cybership II, a scaled model of an offshore supply vessel to study dynamic positioning. This model is used to investigate performance of various other control schemes. Dynamic positioning of an offshore research vessel is simulated in different sea conditions (calm to phenomenal). A control scheme based on three separate fuzzy logic controller with an non linear passive observer and a feed-forward decoupling compensation for the yaw and the sway is designed, discussed and validated in comparison with the PID and the LQR. The frequency response of the fuzzy controller is compared with the PID and the LQR using the bode plot
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