| Summary: | 碩士 === 淡江大學 === 機械工程學系 === 88 === The objective of this thesis is to develop fuzzy pressure and thermal models for a thermal barrel of an automatic plastic extrusion process. Meanwhile, an internal model control low is designed to verify the performance of the proposed fuzzy systems.
Based on the input and output information about the pressure at the outlet and the temperature inside the barrel, the clustering method is utilized to model and identify the structure and parameters of the fuzzy systems. In pressure model, the input command is the rotor speed of the driving screw, while the heat-flow rate of the heater is the command of the thermal model. Compared to a linear model in the literature, the developed fuzzy systems have smaller values of mean squared error (MSE) with the real input-output systems.
An internal model control is employed in order to evaluate the performance of these nonlinear fuzzy systems in control processes. The integrated pressure and temperature control system is tested on a plastic extruder. The experimental results show that the steady-state errors are in ±30 psi for the pressure control, and in ±1.4℃ for the temperature control.
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