Research On The Bi-direction Electro-hydraulic Proportional Tension Control System With High Inertia Loads

The electro-hydraulic proportional tension systems with high inertia loads have been used widely in many fields, for example the ocean winch using in cabling undersea, the tensioner, jigger, and so on. Because of the high inertia loads, when the tension systems move from one stable state to another, for instance, during the process of system startup, accelerated or decelerated motion, etc, the tension oscillates and fluctuates severely, and the relative stability of the system is rather worse. It will destroy the cable and cause the grave accident. So it is a vital issue that how the tension systems with high inertia loads improve the dynamic characteristic and anti-interference capability to insure the stability, precision and celerity of tension control. However, the research on these aspects cannot be attached importance to enough.Under the background of the above-mentioned, target project is the loads simulation tension winch system. Based on analysis on a great deal of domestic-abroad materials and all kinds of tension systems, a new electro-hydraulic tension compound control circuit based on pressure regulation circuit adopting electro-hydraulic proportional relief valve with throttle control unit is presented. Employing some methods combining the theoretical analysis and the experimental research, the control characteristic of variable-tension control and the anti-interference capability of the proposed tension system with high inertia loads are studied more systemically and profoundly. Not only there is a higher scientific value, but also the device is applied and there exists a higher engineering value. It gives some design and experimental ideas to the farther research on the design and control for the electro-hydraulic proportional tension systems with high inertia loads.The main content of each chapter is summarized as following:In chapter 1, at first, the cause of formation of tension, the fundamental and significance of tension control are expatiated on. Then, the development status in quo of the electro-hydraulic tension systems and the main focus of research are summarized. Based on the above-mentioned, the proposal and research content of the thesis are proposed.In chapter 2, a new electro-hydraulic compound control circuit based on pressure regulation circuit adopting electro-hydraulic proportional relief valve with throttle control unit is presented, the mathematics model is built and the theory is analyzed. The new tension system not only can realize bi-direction tension control, but also can improve the relative stability of the system by utilizing the pressure-flow gain of throttle control unit to enhance the damping of ratio. At the same time, aimed at the column of the cable, the automatic structure of arranging cable is designed. At last, the experimental device of the loads simulation tension winch system with high inertia loads is introduced.In chapter 3, at first, the selecting-space and realization rule of the pressure-flow gain are studied. Through the rsearch on the dynamic and static characteristic of the closed-loop tension system with PD controller, it is pointed out that the pressure-flow gain of throttle control unit can resolve the contravention between improving the tension response speed and enhancing the damping of ratio of the tension system. Based on above-mentioned, for realizing the stability, precision and celerity of variable-tension control, a segmented variable coefficient PID control strategy with dynamic limit is proposed, and the validity is proved by experimental research. At last, the characteristic of variable-tension control of adjusting velocity is discussed theoretically.In chapter 4, a higher accuracy control strategy—adaptive robust control method is introduced. Through the analysis and research on the theory, according to the differences between the winding and unwinding, a direct adaptive robust electro-hydraulic tension control method is proposed. The method is also carried out experimental study on precision of constant tension control along with segmented variable coefficient PID control strategy with dynamic limit. The theoretical analysis and experimental results show that the direct adaptive robust electro-hydraulic tension control method is effective to the uncertain factors and nonlinearity of electro-hydraulic tension system, and the precision of tension control is higher. It is very good for the high accuracy control to the tension control systems.In chapter 5, the study is on the interference when feeding velocity is altered under winding or towing velocity is changed under unwinding. Based on the electro-hydraulic compound control circuit, a new compound control strategy is proposed, which the torque controller works cooperating with the pressure-flow gain controller. It can obtain optimal dynamic damping ratio through real-time altering pressure-flow gain of the throttle control unit to improve the dynamic characteristic and anti-interference capability of tension follow-up control for the tension system with high inertia loads. The experimental research is also done.All achievements of the dissertation are summarized and the further research work is put forward in chapter 6.