Research Of Real-Time Control Strategies For Internet-Based Hydraulic Position System

Networked Control System received great concern both from theoretical research and engineer application fields. And the Internet-based real-time control system is the most challenge subject in that field. Meanwhile, hydraulic position system is widely used in engineering.The application of Internet-based real-time control in a hydraulic position system, which is based on high speed on/off valve, is studied in this thesis. The research work is focused on the theory and experiments of the application of fractional order PID (FOPID) in this system and algorithm to compensate large Internet induced delay. The main work is as follows:1) The principles of Internet-based real-time control system and high speed on/off valve based hydraulic position system are introduced. And the origins and influence of challenge problems, such as network-induced delay, data dropout, data transmission noise and nonlinear properties of high speed on/off valve, are investigated in the thesis. 2) The mathematical and AMESim-based models of the hydraulic position system are built in this thesis. And S-function based Internet channel model is established according to the test results.3) The FOPID algorithm is introduced for this control system. The co-simulation, Hardware-In-Loop experiments and Networked Control experiments show that the control system's performance, such as stability, precision and noise rejection, is promoted by this algorithm.4) Based on the FOPID, another new algorithm, which is called FOPID with reference signal's derivatives forward feed, is proposed in this thesis. The co-simulation, Hardware-In-Loop experiments and Networked Control experiments reveal that it can significantly improve the system performance under the large Internet-induced delay.