Research On Digital Valve Nonlinearity And Flutter Compensation

The nonlinearity of electro-hydraulic control system is mainly the result of electro-hydraulic control valves and power components - load bodies, they are largely restricted the system performance improvement. Since the nonlinearity effect, the actual output of the system fluctuates around the expected value, it affects the control accuracy of the system, even turns up limit cycle oscillation, brings about system instability. The control valve is playing power amplification role in electro-hydraulic control system, its nonlinearity adverse effects had on system also is able to be enlarged. Therefore, the superior or inferior of the control valve function plays an all-important role.2D digital valve's gear transmision organization has hysteresis, and plus lap of valve port is also to form nonlinearity, they may creat adverse effect to accuracy and function of electro-hydraulic control system. The flutter can compensate for the nonlinearity of digital valve,through the establishment of digital valve related mathematical models and simulation analysis of MATLAB, then to form a theoretical foundation. On this basis to build an experiment platform, the experiment result indicates: the input of digital valve overlays the flutter signal, can come true to compensate the hysteresis nonlinearity. The main tasks of this dissertation are listed as followed:Chapter 1, simplely introduce the background and significance of nonlinearity characteristic property of the digital valve; expound current situation at home and abroad; then sum up the field of electro-hydraulic control components and the developing of electro-hydraulic control technology; at last list the main problem mission.Chapter 2, study the hysteresis of digital valve and flutter compensation, one by one to introduce that the concept of hysteresis, summarize digital valve's operating principle, build up digital valve mathematic models, analyze the cause of hysteresis, briefly expound the compensate mechanism, build up the backlash models as well as simulation analysis under MATLAB environment.Chapter 3, study the dead-zone nonlinearity of digital valve and flutter compensation, one by one to introduce that the concept of the dead-zone nonlinearity, build up mathematic models of the dead-zone nonlinearity, analyze the cause of the dead-zone nonlinearity, briefly expound the compensate mechanism as well as simulation analysis under MATLAB environment.Chapter 4, an experiment system was built to research the nonlinearity characteristic property of the digital valve and flutter compensation, and tell the details; and then, respectively study and analyze the hysteresis nonlinearity; at last get the experiment conclusion in studying from the experiment.Chapter 5, the summarization of this dissertation and the prospect of this research are given.