Motion Tracking Control Of Actuator In Active-truncated Model Test Of Mooring System

With the increase of working depth of the deepwater platform,truncated mooring system test has been researched at home and abroad.The active-truncated mooring system test is one of the current research orientations,which can solve the contradiction between the existing wave basin and the water depth of deepwater platform.Besides,it can also meet the dynamic characteristic similarities of the mooring system.The main problem of the active-truncated mooring system test is the motion tracking control of the actuator at truncation point,fast calculation of mooring system characteristics,etc.This paper focuses on the study of the actuator at truncation point and its motion tracking control.Firstly,the applicable actuator such as Stewart platform is selected and its advantages are analyzed.The kinematics of the actuator is studyed and its simulation model is built by MATLAB/Simulink.The correctness of the simulation model is verified using irregular displacement motion signals.What's more,the workspace range is solved by using the kinematics of the actuator.Secondly,for the driver that drives the actuator motion,the simulation model of driver is built by MATLAB/Simulink.The general characteristics of the driver and the factors that cause errors are studied.The MATLAB system identification toolbox and RBF neural network identification method are used to establish the mathematical model of driver,which is used to describe the driver output characteristics and perform control algorithm research instead of the driver.Combining the identification results of the two methods,the control algorithms such as feed-forward control,disturbance observer,minimum variance self-correction control,RBF neural network inverse model control and the control effect of the driver under these algorithms are studied.The motion tracking effect of irregular displacement motion is compared to analyze the advantages and disadvantages of these methods.Thirdly,combined with the actuator kinematics model,the driver model and the control method,the effectiveness of control methods for the actuator is studied.Finally,the large time-delay process in the active-truncated mooring system test is studied.The compensation effect of the cubic spline interpolation method on the time-delay process is studied.The effect of collected historical data points,time delay and sampling time on the compensation effect is studied.The selection criterion for sampling time is also studied.The results show that the established Stewart platform kinematics model is correct,feed-forward control,disturbance observer,minimum variance self-correction control,RBF neural network inverse model control can effectively improve the motion tracking accuracy of driver,and each of the four algorithms has its own application.The control algorithms designed for the driver are still valid for the Stewart platform.The cubic spline interpolation algorithm can effectively compensate the time delay,and the smaller the sampling time,the higher the compensation precision.The research results of this paper provide a theoretical and methodological reference for the motion tracking control of the actuator at truncation point in active truncated mooring test of deepwater platform.