Applying Fuzzy Logic in a Complex Temperature Control System

摘要

Choosing a control strategy for an unknown process is risky and can set one up for failure. If the process is one-of-a-kind and time constraints are tight, this can pose an even graver risk to success. On the other hand, significant cost and time reduction can be realized. We selected a fuzzy logic control strategy to run a complex test setup requiring multi-loop temperature feedback control, thermal ramping, mode switching, and temperature profile tracking. Setup changes were made almost daily in the beginning, some requiring considerable thought and effort to address. Though the system's behavior was unpredictable and non-linear, fuzzy logic proved to be an amazingly robust and flexible control strategy that worked well for us. It seems to be applicable to virtually any control problem, whether simple or complex, small or large, with a high probability of success. This paper will discuss the particular control requirements of this test, the technical challenges faced by both the system designer and the instrument/controls designer in getting everything working, how well the system performed, and what was learned from the experience that could be applied to practically any difficult control problem to help decide if using fuzzy logic makes sense.