An Enhanced Fuzzy Control Strategy for Low-Level Thrusters in Marine Dynamic Positioning Systems Based on Chaotic Random
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An Enhanced Fuzzy Control Strategy for Low-Level Thrusters in Marine Dynamic Positioning Systems Based on Chaotic Random Distribution Harmony Search Defeng Wu1,2 • Yuxiang Liao1 • Chaodong Hu1 • Shuanghe Yu3 • Qingyuan Tian1,2
Received: 22 February 2020 / Revised: 6 October 2020 / Accepted: 13 October 2020 Taiwan Fuzzy Systems Association 2020
Abstract The required control force vector is distributed by the thrusters in marine dynamic positioning system (DPS) to obtain the desired thrust and angle of each thruster. The thrust of the thruster is mapped to the speed of the thruster, and the low-level thrust controller adjusts the speed of the thruster to achieve the vessel’s dynamic position. Based on the previous research, the permanent magnet synchronous motor (PMSM) is selected as the lowlevel driving motor, and it is combined with the propeller to form the low-level thrusters for the DPS. The fuzzy control strategy is selected for the PMSM controller design, and the proposed chaotic random distribution harmony search (CRDHS) algorithm is used to optimize the fuzzy controller rules’ weights. The proposed CRDHS employs a chaotic map for rule weight adaptation in order to prevent the conventional harmony search to get stuck on local solutions. By adjusting the weights of each fuzzy rule via CRDHS, more consistent control performance is achieved. The required fuzzy output and the fuzzy controller are used for control of the PMSM. Simulation results show that under load disturbance, the fuzzy controller based on CRDHS has better control performance.
& Defeng Wu [email protected] 1
School of Marine Engineering, Jimei University, Xiamen 361021, People’s Republic of China
2
Fujian Provincial Key Laboratory of Naval Architecture and Ocean Engineering, Xiamen 361021, People’s Republic of China
3
School of Marine Electrical Engineering, Dalian Maritime University, Dalian 116026, People’s Republic of China
Keywords Dynamic positioning Low-level controller Permanent magnet synchronous motor Fuzzy control Chaotic random distribution harmony search
1 Introduction The dynamic positioning system (DPS) has become a necessary support system for ocean explorations. After the thrust allocation algorithm in DPS distributes the expected resultant force and moment to each thruster, each thruster obtains a command of the desired thrust and then adjusts the rotational speed of the thruster through the local controller of the thruster to achieve the desired thrust. The thrusters in DPS are mainly classified into three types, namely, tunnel thrusters, azimuth thrusters and pod thrusters. Tunnel thrusters and azimuth thrusters are the most widely used in DPS. As the executing agency of the fixedpoint positioning task of the power system, the accuracy of thrust generation and the reliability and safety of operation are related to the survival of the dynamic positioning (DP) of the ship. This parameter is an important guarantee for the successful completion of special operations at sea; therefore, thruster control plays a vi
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