- Winter 1995 "Update" Newsletter Article -

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'Fuzzy' logic
Researchers explore agricultural applications of new computer software technology

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From CATI Publication #950101
Copyright © 1995. All rights reserved.

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A CSU, Fresno Industrial Technology professor is exploring agricultural applications of a new technology that mimics human thought patterns in controlling industrial equipment operations.

Professor Matthew Yen's research is focused on the application of "fuzzy logic" in the control of equipment such as heaters, motors, pumps, valves and sprinklers used in the food processing industry and other automated agricultural operations.

In order to automate these processes, temperature, motor speed, liquid level, pressure, humidity, flowrate and other variables must be constantly monitored and adjusted according to prescribed schedule. Simple on/off controls may overshoot, undershoot or fluctuate around the desired setting values.

"Fuzzy logic control enables the system to tightly follow the control prescription in a smooth manner," Yen said. "It is an emerging technology widely used by the appliance industry and process industries in Japan."

The concept fuzzy logic controls was first proposed in 1965 by L. A. Zadeh and is based on the "fuzzy estimation" or "chunking" of human thinking rather than precise mathematical computation. A control system based on fuzzy logic has the following advantages: 1) It is easy to implement since it uses "if-then" logic instead of sophisticated differential equations; 2) It is understandable by people who do not have process control backgrounds; and 3) Software and hardware tools are readily available for applying this technology.

Generally speaking, the procedures of fuzzy logic control are these: A set of input data from an array of sensors is fed into the control system. The values of input variables undergo a process termed as "fuzzification," which converts the discrete values into a range of values. Fuzzified inputs are evaluated against a set of production rules. Whichever production rules are selected will generate a set of outputs. Output data are "defuzzified" as distinctive control commands.

Professor Yen has received seed money from the California Agricultural Technology Institute to explore potential uses of fuzzy logic in agriculture industries. In an initial project to demonstrate application of the technology, Yen guided an industrial technology student in developing a prototype temperature control simulation unit. The researchers used FIDE software by Aptronix Inc. and an MC68HC11 microcontroller provided by Motorola Inc.

Besides temperature controls, fuzzy logic has been implemented or proposed for many other processes in food technology, namely aseptic processing; diagnosis of principle causes of breakage during drying; determination of key ingredients for new products; evaluation of the "doneness" of beef steak; intelligent irrigation; automated feeding systems; and so on.

"The bottom line objective is to develop a robust and intelligent automation system." Yen stated.

Professor Yen is interested in input and/or support from the private industry on other potential applications of fuzzy logic. He may be contacted through the Department of Industry Technology at (559) 278-4201.

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