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Issue
103, February 1999
Truck
Speed Limiter Control
by
Constantin von Altrock
Start
•
Control
Requirements •
Mechanical
Design •
Fuzzy-Logic
Controller •
Implementation
•
Results
•
References
& Sources
RESULTS
After optimizing the fuzzy-logic
rule strategy on different trucks and various load conditions,
the speed limiter demonstrated the response curve shown
in Figure 1 (blue line). The fuzzy-logic controller achieves
a much smoother response, doesn’t show overshoot
behavior, and provides a higher accuracy of keeping the
speed limit compared to a conventional controller.
The final fuzzy-logic system
was compiled to PIC assembly code by fuzzyTECH
and required 417 words of ROM space and 32 bytes of RAM.
The RAM space can be used for other computation tasks
such as preprocessing and filtering while the fuzzy-logic
system isn’t running. The entire fuzzy-logic system
needs less than 2 ms to compute on the PIC16 MCU.
I’ve demonstrated that,
with a little bit of fuzzy logic, you can solve difficult
control problems using conventional design techniques
and by putting your own engineering experience to work.
Not only that, but you can
design a solution using visual software tools and generate
highly optimized assembly code for most microcontrollers
at the push of a button. Now you’re on the way to
significantly reducing design time.
Constantin von Altrock
began research on fuzzy logic with Hewlett-Packard in
1984. In 1989, he founded and still manages the Fuzzy
Technologies Division of Inform Software Corp., a market
leader in fuzzy-logic development tools and turn-key applications.
You may reach him at cva@inform-ac.com.
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