Research On A Water Hydraulic Position Synchro Control System

The hydraulic position synchro systems have many advantages such as simple structure, easy to buildup, easy to control by automation and output power is great. So the hydraulic system has wide applications in many fields. The traditional hydraulic systems use oil as the work medium and are restricted for the purpose of safety and cleanness. Water hydraulic system is anti-burning and more safety and clean to environment. It's one of the develop directions of current international fluid transmission field. It can replace the oil hydraulic system in some occasions which has high requirements of anti-fire and environment protection, for examples the food production, upper water stage and sea engineering. It has a wide prospect.This thesis makes a research on development of water hydraulic technology and buildup a water hydraulic position synchronizing system in the condition that water hydraulic control valves are limited. It also studies on the control theories and testing methods of the system. The main works of this thesis include:This thesis points out that the system is actually a position control system with position feedbacks. It classifies position synchro systems to several kinds and analyzes the characteristics of them. The system's two cylinders are controlled separately. One is controlled by Danfoss's manual throttling control valve and the other one by two Danfoss's proportional flow control valves. The latter cylinder should follow the former. The two proportional valves'input signals are also discussed in the thesis.Design of the low friction cylinder which will be used in this system is done. In order to obtain high performance, the low friction is essential for cylinder. The thesis studies on the friction phenomenon and some improvements are put forwards to reduce friction and stick-slip of the piston. Some strategies are pointed out to solve the leakage, corrosion and low lubricant problems of water hydraulic cylinder in thesis. A test is made and the result shows the cylinder works normally and has low friction.The mathematical models of the flow control valves, cylinder and the whole control system are built. Some parameters of these models are expatiated. The relating real-time simulations are built by using the MATLAB/SIMULINK toolbox. The simulating result shows factors which influence the natural frequency and damping factor of cylinder. The static and dynamic characteristics of control system are also get from simulating models.