Hi!

I'm doing electrical heating control project with 8052 (final year project in enrgetics). I got it done with PI-law and the result was acceptable. And now I try to do it with fuzzy logic (just for to get my project longer).

I have never implemented fuzzy logic before, but I think I have understood the main process of it. I wrote the program, but I have troubles in composing right the rule base. I implememented it on heating a litre water, but the the transient response is quite bad. The temperature is oscillating around setpoint (+0,4 and -0,8 degrees celsius) like with on-off control. I think I will get a litle better reaction after furter tuning, but maybe I have implememnted it in wrong way.

What will be the output variable when error and change in error is zero? I have seen that some authors put medium output value (output membership function) to compensate the heat loses. But in those case i have put very low output value.

And for second, I have 7x7 rule base and use 8-bit ADC to get resolution 0,2 degrees celsius. The sampling time is 2,5 seconds. That kind of resolution might be to less to get smooth output?

Thank you!

Hendrik