I would say that FL is more complex to implement properly, than PID, with full de-fuzzification, weighted functions etc? Sure the basic if-then statements are simple but they arent technically FL until you combine all outputs, defuz with weightings etc etc...? I've implemented PID on an 08M for fan control in the past, that wasn't too interesting (or effective), i was looking for something a tad more fun really:
My system is quite complicated in operation for on 08M, it consists of 3 parts:
Fan - PWM control
Radiator (2 temp sensors, one checking ambient temp air, the other water exit temp)
Heat exchanger (that the rad cools the water for)
The heat exchanger sits atop an engine and tends to heat up while stationary, likewise the rad gets no natural airflow, in this state the water heats rapidly and if not kept cool will rapidly heatsoak the hardware, taking ages to cool the HE back down. However the heat exchanger often heats up small "batches" of passing water in small quantities, these tend to be less important as they mix with cold fairly well to reduce the effect.
Hence I'd like a system that knows if the system is heating up long term (stationary) or just transiently, in which case the fan wont be quite so full-on, to save power.
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I think the point of FL is that it can work very effectively with vague ideas of control, it doesnt need modelling and it doesnt need precise parameters to be tuned like gains on a PID - it takes care of that, for the most part, without too much interference. I think a specifically tuned PID would be a better solution, in terms of ideal response, but the fuzzy can be implemented without much effort and work to 95% of that of the perfect PID. Also fuzzy extends to multiple inputs without vast increases in the number of functions to be tested? I've not looked in massive detail, but I do have reports of fuzzy working as well to control robot manipulators with guesses at parameters as a fully tuned PID, hence my interest really. I think it might be overkill for a fan controller, but im interested and what else is spare time for?!
I think FL is also very much parameter independant - the classic example thats quoted is the inverted pendulum test, a FL controller was set up to control an inverted pendulum, the guy then placed a mass on top of the pendulum (which would screw up a PID as the process parameters have changed) and the FL adapted quite happily, keeping the pendulum upright.