Research Of Fuzzy PID Control For Water Hydraulic Parallel Cylinders Synchronous System

Water hydraulic technology is an important research direction in the field of fluid transmission.It meets the requirements of energy-saving,environmental protection and sustainable development.It has a broad prospect of application.The synchronous control of water hydraulic parallel cylinders is an important application field of water hydraulic system.It has many advantages such as simple structure, non-pollution medium ,green and environmental protection, antiflaming, etc.It has been widely used in the environment of higher requirements such as food and medicine, with the development of science and technology, the application filds of Water hydraulic technology will be more and more widely .Combining the global development status of water hydraulic technology and synchronous control system, the operation process of the master-slave mode synchronous position control of water hydraulic parallel cylinders has unsatisfactory synchronous control results.Water hydraulic system and oil hydraulic system are compared.the different synchronous control mode are analyzed.the synchronous control strategys are researched. The main works of this thesis include:The mathematical model of the master-slave mode synchronous position control of water hydraulic parallel cylinders is established, especially the mathematical model of water hydraulic proportion flow valves and water hydraulic cylinder.the stability and dynamic performance of system are analysed.The influence of load to the natural frequency and damping of cylinder and the whole control system are researched.For the dynamic function of the system is not ideal, conventional PID controller is designed to rectify the system, and the proportional degrees meathod is used to set conventional PID parameters. Because the system exists factors such as time-varying and nonlinear, PID controller is hard to adapt to the changes of system parameters, the results of control is not ideal. Fuzzy self-tuning PID controller is designed to realize PID parameters online adjustment, small overshoots,fast response time, and the displacement of the two water hydraulic cylinders follows well, two cylinders synchronous displacement difference value is small,the control effect are superior to the conventional PID control.Lastly the controller based on the BP neural network fuzzy PID control technology is proposed.It combined the fuzzy control and neural network control. the control effect such as response time, overshoots and steady precision are superior to the fuzzy self-tuning PID control.