| Summary: | 碩士 === 國立臺灣大學 === 化學工程學研究所 === 90 === In a multi-loop control system, interactions usually exist among the control loops.Because of these interactions, design of controllers to achieve satisfactory loop performance encounters much more difficulties than that for a SISO loop. In this article, we continue Chiang's research [5]; he defined the Effective open-loop processes(EOPs) from dynamic analysis of processes, then he found FOPDT or SOPDT model to approximate EOPs, and designed controllers. But, to find such approximate models are tedious for multi-loop controller design. In addition, Chiang's research is suitable for use when the transfer function of multi-loop system is known.
In this article, we consider multi-loop controller designs for systems when transfer function is available or not available. If loop's transfer function is available, we utilize the
benchmark system[15] to approximate controllers, and obtain ultimate gain、ultimate frequency、steady state gain in a
specific loop through frequency response data; if loop's
transfer function is unknown, a method that starts with an initial choice of controllers, and use relay feedback test to obtain ultimate gain、ultimate frequency、steady state gain in specific loop. Eventually, parameters of controllers are calaulated by substituting ultimate gain、ultimate frequency、steady state gain into a set of tuning formula.
This design procedure is formulated for 2x2 system, and is extended to other multi-loop system.
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