Research On Optimization Algorithm Of Thrust Allocation In Semi-submersible Platform DP System

With the human research on the ocean more and more in-depth,many marine-related areas of science and technology products were born,the dynamic positioning system is one of the most widely used products,it refers to a closed-loop control system that a ship or other marine device using the control system to control its own propulsion system withstand the effects of environmental disturbances and keep it at the desired position and heading.The thrust allocation unit is an important part of the dynamic positioning system,its main task is to allocate the force and torque commands issued by the controller reasonably and efficiently to the various propellers of the ship to satisfy the basic requirements of the total thrust generated by all propellers to offset external environmental disturbances and to make the energy consumed by the system minimal.In this paper,optimization algorithm is researched for the thrust allocation system of a semi-submersible drilling platform.Firstly,based on the outline of the motion-related coordinate system of the platform,the mathematical model of the semi-submersible platform and the disturbance of the marine environment(wind,wave and flow)are established,and a PID controller is designed.The simulation of platform mathematical model is carried out by without environment interference and environmental interference.Secondly,an optimization model of thrust allocation is established,and an improved particle swarm optimization algorithm is proposed.Summarize the thrust allocation problem,detail the thrust allocation actuator and propeller arrangement,and establish the mathematical model of thrust distribution.In order to improve the defect of the particle swarm optimization algorithm,an improved particle swarm optimization algorithm based on the average evaluation value is proposed,the algorithm is verified by the classical test function,the simulation results show that the effectiveness of the algorithm.Then,after the objective function of the thrust allocation of the semi-submersible platform is given,the process of implementing the thrust allocation based on the improved particle swarm optimization algorithm is designed,which is prepared for further thrust allocation simulation.Then,the optimization algorithm of thrust allocation is simulated.In two different test environments,the simulation of the thrust allocation with the improved particle swarm algorithm is carried out,the simulation results show the effectiveness of the proposed algorithm in thrust allocation.Then,the simulation and analysis of the thrust allocation based on the sequential quadratic programming algorithm and the standard particle swarm algorithm are carried out in the first test environment,and the advantages and disadvantages of the three algorithms are analyzed.Finally,the research work of this paper is summarized systematically and the shortcomings are put forward,which points out the further research direction of thrust distribution of dynamic positioning system.