| Under the background of the large-scale ships and the continuous expansion of the navigation scope of the marine cargo transportation,in order to better deal with the unexpected sinking of ships and other emergencies,the wreck salvage technology begins to develop in the direction of large depth and large tonnage,which poses a new challenge to the rescue and salvage equipments.In recent years,with its excellent performance,the wreck salvage scheme based on hydraulic synchronous lifting technology is more and more widely used in the salvage engineering of large tonnage and deep sunken ships.But the hydraulic synchronous lifting technology also shows some shortcomings in practical application.In the case of worse sea conditions,it is difficult to meet the requirements of high-precision control by using the traditional control methods.This paper mainly studies and analyzes the synchronous control method of hydraulic lifting system for wreck salvage.The main contents are as follows:(1)The motion response of barge in frequency domain and time domain is calculated by Aqwa.On this basis,Adams is used to simulate and analyze the tension change of steel strand in the process of wreck salvage,which lays the foundation for the next stage to investigate the robustness of the algorithm.(2)The mechanical structure and hydraulic system of the hydraulic lifting device are designed.The characteristics of the proportional directional valve and the hydraulic lifting cylinder are analyzed,and the state space model based on the position variables is created.The hydraulic model of the hydraulic lifting system is established by using AMESim-Matlab joint simulation platform,and the mathematical model of each hydraulic lifting cylinder is identified by using the least square method,which lays the foundation for the next stage of control algorithm design.(3)The main influence factors of synchronization performance of hydraulic lifting devices are analyzed in detail.Considering the actual working environment of hydraulic lifting devices,the compound control algorithm with speed feedforward and position feedback is adopted to design the controller of hydraulic lifting cylinders.On this basis,the synchronization performance of adjacent cross coupling synchronization,equivalent synchronization and master-slave synchronization control strategies are compared.In order to solve the problem that the coupling compensation coefficients are not easy to determine in the adjacent cross coupling synchronous control strategy,an adaptive fuzzy compensator is introduced and verified by numerical simulation.(4)In order to further improve the control performance of the system,a discrete fuzzy sliding mode control algorithm is introduced based on the adaptive fuzzy adjacent cross coupling synchronous control strategy.Firstly,the basic theory of discrete sliding mode control is analyzed,and the discrete sliding mode controller is designed according to the model of hydraulic lifting cylinder.In order to weaken the chattering of the system and strengthen the robustness of the system,a fuzzy controller is designed to adjust the reaching law parameters.The simulation results show that compared with the compound control algorithm with speed feedforward and position feedback,the system with discrete fuzzy sliding mode control has better performance in position tracking and synchronization control. |
