Rick Grehan
The
fuzzyTech-MP Explorer
($295) is a combination of software and hardware for learning how to develop a fuzzy application. Though I have seen fuzzy logic applied to decision-making systems such as fuzzy-logic-based spreadsheets, the fuzzyTech-MP Explorer from Microchip Technology (Chandler, AZ, (602) 786-7200; fax (602) 899-9210) concentrates on using fuzzy logic in system control applications.
The hardware side of the Explorer is the fuzzyLab, a small circuit board powered by an AC adapter and populated with LEDs, push buttons, a pair of potentiometers, RS-232 circuitry, a socketed PIC-family processor, and a thermistor/resistor pair (bonded together in a plastic sheath). One output pin
of the PIC processor is connected to the resistor. By varying the duty cycle of a pulse wave out that pin, you can heat the resistor. Via another I/O pin, the PIC processor reads the thermistor's temperature. The processor on the fuzzyLab "talks" through the serial port to the Windows-based fuzzyTech development system. The idea is to produce a fuzzy-logic control program that can heat the thermistor to a target temperature and keep it there.
This sounds simple, but fuzzyTech's tutorial will show you that this is not the case. In the tutorial, you operate the heating manually. I quickly discovered that when you turn the heater up too quickly, you overshoot the optimum temperature. If you back off too fast, it undershoots as it cools down. (I discovered that I would make a lousy thermostat.)
The next step is to activate the fuzzyTech development system. You define "crisp" values: real-world inputs and outputs (e.g., temperature and duty cycle). The crisp inputs are read into the system and "fuzzi
fied" into linguistic terms: A temperature of 30C might "fuzzify" into the linguistic term too_cold. Linguistic terms pass through a set of IF...THEN statements that you construct. These statements determine output linguistic terms. The output is "defuzzified" into a crisp output value that controls the amount of current going into the resistor.
All this time, you're learning fuzzy-logic fundamentals: how to define linguistic terms, how crisp input values convert to membership within linguistic terms, how output linguistic terms convert to crisp output values, and so on. Best of all, you can see if what you've learned works using the included fuzzyTech software.
The fuzzyTech development system provides a visual IDE (integrated development environment). Your system's details are all saved in an FTL (fuzzy technology language) source code file. Once your program works properly, you can output PIC16xx-compatible source code. (You need a separate product to assemble the source code into executable
code.)
You can even build a simulation in C and use fuzzyTech to control it. The product uses Windows messages as the communications route. Source code for this interface is provided. Microchip includes a sample program that uses this technique. It simulates using a crane to unload boat cargo and uses fuzzyTech to control the crane's motor. If you want to get your fuzzy feet wet, I can think of no better way than this.
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Microchip's fuzzyTech-MP Explorer includes hardware (shown) and software that lets you explore fuzzy-logic programming.
Microchip's a Hands-On Introduction to Fuzzy Logic
