| The propulsion system and control system both core subsystems of the dynamic positioning system(DPS).The propulsion system mainly includes azimuth thruster,lateral thruster and rudders,while the motion control system includes motion planning,guidance,controller and thrust distribution module,etc.The thrust distribution module is a key part.When designing it,not only the operating sea condition and task requirements,but also various constraints such as the rotation prohibition zone of thruster,rotation speed,maximum thrust and power distribution,must be considered.Whether the thrust distribution module is designed properly will directly affect the operation performance of the DPS.In this paper,a complete set of dynamic positioning control simulation system for the HYSY286 ship is designed.The main contents of this article are as follows:1)First,a combination of momentum conservation principles,geometric principles,and empirical formulas is used to set up the hydrodynamic and kinematic model,as well as environmental load model for the ship.And the relative coefficients are revised based on the DPS analysis report.Second,based on the FS3510 azimuth thruster installed on the HYSY286 ship,an asynchronous control frequency simulation method for the slewing dynamics system of the slewing thruster is established,and a control method for quick tracking of the target azimuth is proposed.The azimuth and angular speed of the thruster,and dynamic characteristics of the hydraulic system under different target azimuths are analyzed.Then,based on the squirrel-cage asynchronous motor driven propeller rotation system of the main thruster of the HYSY286 ship,a mathematical model of the propeller dynamics system driven by the inverter controlled asynchronous AC motor is established.Dynamic response characteristics of motor and propeller load under constant and changing propeller speed are analyzed.Finally,the physical response constraints of the thruster in the mathematical model of thrust distribution are obtained through simulation analysis.2)For the Joystick&automatic mixed control mode of the dynamic positioning system,a control method combining PID control technology and tracking guidance with three typical modes is proposed,which solved the three path guidance laws of the Joystick&automatic mixed control mode.Motion controllers with three typical mixed control modes are designed,and a DPS simulation system with Joystick&automatic mixed control is built.The control law and ship attitude for the three modes are analyzed through numerical simulation,which proves the effectiveness of the mixed path guidance algorithms and the control methods.3)Firstly,a time-sensitive direct thrust allocation method and a pseudo-inverse thrust allocation method are designed.Secondly,an action set thrust optimization method is proposed to improve the local search capability.Then,a complete DPS simulation system is set up based on the configuration and layout of HYSY286 thruster.Finally,under the fixed control mode,the positioning function and dynamic responses of the DPS based on the three thrust allocation algorithms are compared and analyzed.The influence of the penalty term in the active set method on the allocation deviation is analyzed.The advantages and disadvantages of the three methods are summarized.The results show that the direct allocation method needs less calculation and is stable,but it’s unsuitable for inequality constraints.The pseudo-inverse algorithm is good at real-time operation and is more efficient for propellers with fixed angles,but it can’t be used for multi-objective optimization.The function set method can fully consider the physical response constraint of thruster.It can reduce the thruster worn and has great real-time performance.4)The UI is designed using the Qt Creator software.First,the DPS framework of the ship is built using the dynamic link library.Second,the subsystems of the DPS are programmed into C/C++ code and the API interface is set.Finally,the performance of the DPS simulator are verified through simulation,which provides an important research basis for the design and engineering application of the DPS simulator. |
PDF Full Text Request