Research On Sliding Mode Control Of Dynamic Positioning For Semi-submersible Platform Based On Low Pass Filter

In recent years,half of the discoveries of major oil and gas fields around the world are in the ocean,especially in deep water area.As a major maritime country,China has the world fourth long coastline,the area under whose jurisdiction covers a third of the territory.And China's south sea is one of the world's four major offshore oil and gas resources.Therefore,China has a unique advantage in deep-sea oil and gas exploration.However,compared with the developed countries,the development and utilization of marine resources in China lacks the experience and expertise deep-sea projects.For this reason,China national offshore oil corporation and the United States jointly designed and built the first deep-water special marine equipment—China national offshore oil and deep-water semi-submersible drilling platform,the maximum operating depth is 3,000 meters,the maximum drilling depth is 10,000 meters.This thesis takes the semi-submersible marine drilling platform as control plant,mainly researches on the core technique—dynamic positioning technique.The mathematic model of semi-submersible marine drilling platform and the model of marine environment disturbance and model uncertainty are given from the angle of kinematics and dynamics mechanism.In view of the chattering control input problem caused by the actual industrial system operation and the Marine environment disturbance and model uncertainty,a robust sliding mode controller based on low-pass filter is designed,the rationality of the controller is verified by the Lyapunov stability proof,the stability and effectiveness of the designed controller is verified by program simulation.In view of the velocity and acceleration signal is difficult to measure in real time and accurately in actual operation of the industrial system,the differentiator based robust adaptive sliding mode controller is designed,adaptive control is added on the basis of the differentiator observation,the dynamic positioning system of ocean platform is controlled more micro and precisely.Finally,in view of marine environment disturbance and model uncertainty is difficult to measure in real time and accurately in the process of dynamic positioning of semi-submersible drilling platform,a sliding mode controller based on the second-order sliding mode disturbance observer is designed.The problem of disturbance observation and elimination is solved.Simulation results showed that the three control schemes could ensure the semisubmersible drilling platform track the desired point and trace steadily and precisely in the dynamic positioning process,and kept strong robustness to the environment disturbance and model uncertainty.