Study On Bounded Control Of The Active Heave Compensation System

The sea is rich in energy and resources.With the increasing of population,the available energy and resources on the land are decreasing or even exhausted,and people's exploration and development of the ocean is becoming more and more diversified.It is particularly important to have relatively perfect offshore production installations on this basis.In many Marine mining activities,most of them involve the underwater operations of the ocean.However,due to the interference of ocean waves,ocean currents and ocean breeze,Marine equipment will generate motions of 6 degrees of freedom,makes the position of underwater working equipment affected and difficult to accurately control.After installing the hydraulic cylinder heave compensation device,and because of the hydraulic cylinder stroke has the boundary,it is easy to produce the bump.All of these have brought the extremely difficult to the Marine work.In this paper,motion compensation in heave direction is mainly studied.The main research contents of this paper are as follows:In the first chapter,this chapter firstly investigates the development situations of heave compensation system at home and abroad.And on this basis,analyze the advantages and disadvantages of existing system of heave compensation.Then find the common defects existing in the heave compensation systems of the hydraulic cylinder type:when the hull heave exceeds the stroke of the hydraulic cylinder in severe sea conditions,if the compensation is carried out according to the existing heave compensation algorithm,the system will have a serious impact.This chapter proposes a preliminary solution after analyzing this problem.In the second chapter,the heave compensation electro-hydraulic control system is designed,the force situation of underwater towed body is analyzed,the electro-hydraulic control system is simplified and the mathematical modeling is carried out,then the collision problem of compensating hydraulic cylinder is also analyzed.Finally,the key components of heave compensation system are selected and the system model is built in Amesim.In chapter 3,on the basis of the mathematical model of the system,the heave position compensation control algorithm was proposed which is based on the sliding mode control algorithm.And the effectiveness of the algorithm was verified through Amesim-Simulink co-simulation.Then,in order to illustrate the severity of collision caused when the heave of marine engineering equipment exceeds the stroke of hydraulic cylinder,the working condition of the collision is simulated by adding a switch valve to the original system.And it is pointed out that the protection system based on simple switch valve has limited protection effect on the system in the case of impact.The fourth chapter aims to solve the problem of compensating hydraulic cylinder collision in the severe sea condition by improving the control algorithm.The phenomenon of collision is analyzed from the phase trajectory,and the solution of the bounded control problem is proposed based on the relationship between the synovial surface and the bounded phase plane.After discussing the advantages and disadvantages of several solutions,the bounded control based on the speed limit is selected.Then,the bounded controller was added on the basis of the displacement controller designed before.So that the target was achieved that when it's large values there is no collision,and small values are normally heave to compensate.In this way,the maximum utilization of the stroke of the compensating hydraulic cylinder is realized.Finally,the simulation is carried out with real sea data.In chapter 5,firstly,the basic structure,key component model and operation method of the experiment table are introduced.At the beginning of the experiment,a series of sinusoidal signals with different frequencies and amplitudes are used to carry out relevant experiments on the controller.On this basis,the real wave signals were tested and good control effects are obtained,which verified the feasibility and reliability of the controller design in this paper.In chapter 6,summarize the job schedule and point out the further research direction.