Research On Sliding Mode Control Strategy Of Active Heave Compensation For Deep-sea Crane

With the gradual depletion of petrochemical resources on land,offshore oil and gas resources have become the focus of exploration and development in the world.In recent years,China has also strengthened the exploration of seabed resources.As one of the important equipment of ocean exploration engineering,the deep-sea crane will swing up and down with the undulation of waves during the operation at sea,which has a great impact on the positioning accuracy of lifting.Therefore,the heave compensation equipment must be added between the mother ship and the load,and the active heave compensation technology must be adopted to compensate the heave motion of floating structure at sea.Improve the safety and efficiency of crane deep-sea operation.Based on the sliding mode control theory and combined with MATLAB simulation research,this paper explores the sliding mode control strategy of active heave compensation for deep-sea cranes.The main research contents are as follows:Firstly,the analysis and modeling of each structural link of the deep-sea crane system are carried out,which lays the foundation for the subsequent control strategy research.At the same time,the principle and mode of active heave compensation are elaborated in detail.Then,due to the output delay between the active heave compensation devices of deep-sea cranes,the measurement of load velocity and displacement signal is not accurate enough,which affects the effect of active heave compensation.A class of time-varying output delay observer is designed,which is combined with sliding mode control to control and correct the velocity and displacement measurement signals of load.The delay observer of the system is designed by the delay output signal measured by the load,and the time-varying factor of the system is taken into account.The error feedback between the observed value and the load delay output signal is compensated into the sliding mode controller,so that the corrected load displacement and velocity signal can approximate the ideal signal as much as possible,and the load signal is observed and corrected.Secondly,in order to solve the problem of poor control effect caused by phase lag and system nonlinearity in the deep-sea crane active heave compensation system,a composite control strategy combining sliding mode control with high gain observer and model predictive control was proposed to compensate the load heave velocity.Based on the excellent characteristics of sliding mode control and model predictive control,a sliding mode observer is designed according to the transfer function of load to mother ship,which can track the heave velocity of mother ship in real time and eliminate the phase difference between mother ship and load.At the same time,a model predictive controller is designed to actively compensate the heave velocity of tracked load and improve the control performance of the system.Finally,from the perspective of displacement compensation,aiming at the time-varying parameters of the deep-sea crane active heave compensation system,a fuzzy sliding mode control scheme based on active disturbance rejection is proposed.In order to make the control system in the initial state on the sliding mode surface,eliminate the arrival section,and improve the reference track of the sliding mode surface,the integral sliding mode surface is designed and used as the input of the fuzzy controller to enhance the robustness of the system.The load displacement output controlled by fuzzy sliding mode is introduced into active disturbance rejection controller for active heave compensation.Simulation experiments are carried out under different sea conditions and different model parameters.The results show that the proposed method has high compensation accuracy and excellent robustness,and fully meets the control requirements of active heave compensation for deep-sea cranes.