Research On Sliding Mode Control Of Crane Heave Compensation System Based On Motion Prediction

Heave compensation devices are now widely used in the exploration and development of marine resources.When working on a deep-sea floating drilling platform,the platform will produce up and down movements due to the action of waves,which seriously affects the safety and performance of deep-sea operations,The heave compensation device can effectively buffer and compensate the heave displacement of the platform,so that the drill string is protected from the heave motion of the platform.At present,only the United States and other countries in the world have mastered the heave compensation technology of offshore platforms.However,it started late in the country.In order to break the foreign monopoly,this paper conducts related research on the heave compensation system of the crane on the offshore platform.The heave compensation system of compound cylinder crown block was proposed in this paper.Aiming at the nonlinearity and time delay of the heave compensation system,the Variable Structure with Sliding Mode control and the research on motion prediction were carried out.The main contents of this paper are as follows:In this paper,based on the lifting and sinking compensation system of 350 t crown block,the load condition of the system is and the heave compensation system were analyzed theoretically.The mathematical model of heave compensation system of the compound cylinder crown block was established and the whole simulation model of the system is established in Simulink,which provided a basis for the follow-up control strategy research.On the basis of the mathematical model,a terminal sliding mode controller based on the backstepping method was designed.The sliding mode surface was formed by the displacement error of the traveling block hook,the control law of the system was designed and the stability of the system was judged by the Lyapunov function.Through simulation analysis,it was found that the terminal sliding mode control algorithm could stabilize the control system and made the system get high compensation accuracySiemens S7-300 PLC was used to establish an experimental platform for the crane heave compensation system.Aiming at the problem that complex algorithms were not easy to implement in PLC,the OPC communication protocol was used to implement the control algorithm in Simulink,the terminal control in PLC and the the exchange of Simulink,Win CC and S7-300 PLC.A terminal sliding mode control experiment was carried out to verify the feasibility of the algorithm.Aiming at the problem of time lag of the MRU in the ocean platform,which will affect the compensation performance of the system,the autoregressive AR model motion prediction research was carried out to predict the heave displacement of the ocean platform.The motion prediction was combined with the terminal sliding mode control algorithm and the control model of the system was established.The simulation results show that the compensation rate of the system was improved.