Research On The Thrust System Of The 1000m Mining Dredger's Dynamic Positioning System

As human's exploitation of marine resources goes deep and extends to a broader area, the ship dynamic positioning system (DPS) launches forth on an important mission. Depending on its own power, resisting external interferences (wind, wave and ocean current etc) in command of control system, the fundamental goal of dynamic positioning is to keep ship steadily in given position and yaw angel .It has no influence of ocean depth, positions accurately and rapidly, and operates expediently. DPS consists of three parts-measurement system, control system and thrust system. This paper, according to practical construction object requires takes the research, its' aim is to design and study the thrust system of 1000m mining dredger DPS .The main research works in the paper are summarized as follows.With academic research, this paper reinvents the mathematical models of the ship DPS: two coordinate systems applied into the ship mathematical models; the mathematical models of low frequency and high frequency movements; the mathematical models of environment factors. On the basis of the mathematical models of DPS, this paper establishes the measurement system of DPS, which includes: the position measurement equipment, yaw measurement equipment and some sensing devices. Then the thruster-the actuating mechanism of the ship DPS is analyzed and designed initiatively: beginning with the generic performance, the class of thruster and max needed power, the thruster of the ship DPS is analyzed and collocation scheme of bow and stern screw thrusters is established gradually, by selecting drive mode and taking positioning capability analysis, we get the rational collocation scheme. Finally, this paper establishes the drive model and the thrust distribution unit: the drive model consists of motor, thrust control system; feedback and performance sensing devices; the thrust distribution unit takes charge of distributing composition of forces and torque from control unit to every thruster, where the paper took concreteresearch and simulated by Matlab software tool box, the simulated result satisfies the requirement of DPS.The research in this paper is a simple and brief framework of the ship DPS. DPS scheme verification is needed and in some portions further investigations improved and modified before it putting into practice. In addition, the paper summarizes some experiences used for reference to subsequent work.