比例閥開迴路學習控制系統之研究

Abstract

The use of hydraulic proportional valves in industry is very popular. Because ofthe low frequency response and the effect of time delay in valve dynamics, open-loopcontrol is usually used in proportional valves. So it can not get high- accuracyperformance. In our study, a open-loop learning control system is proposed to improvethe accuracy of proportional valves based on the hardware of original open-loopcontrol system. The system we faced is the inject system of an inject machine and the injecting speed is controlled by a proportional valve. First, we got the first-order linearmodel by the method of identification and then we built the nonlinear model of this system based on the nonlinear characteristics from the analysis of the data we measured. To analyze the property of open-loop learning control system, a similar PID controller like in closed-loop control system was used in a first-order linear system in our simulation of open-loop learning control system. Some nonlinear situations like saturation, disturbance, noise, delay, etc. were also included in our simulation. The results have shown that open-loop learning control can improve the accuracy of the system and could overcome the effect of some nonlinear conditions. In the end, we applied the nonlinear model of the proportional valve to the simulation, the results also showed that it could achieve good response. In the future, we hope to apply the open-loop learning control system to a real system to improve the accuracy.