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Macgyver BR

Plc's Fuzzic Logic

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I agree that temperature and motion/hydraulics controls are not the same and also that Honeywell is one of, if not the best on controllers, I have many (100's) and I have been very satisfied with their product I think one of the reasons that the WAG theory has worked for me is, I have the time to watch the process, by attaching my meter and watching what the controller is doing vs the PV, if I over shoot by 5deg not a big deal, I can adjust it out and the next time around I will get a better response But when it comes to my hydraulics or motion, I tend to watch my step, it can be a devastating if you dont watch what you are doing, high pressures on my presses are over 900000 pounds of force, to me this is a lot With Honeywell's fuzzylogic that Dan posted there are other ways that it can be accomplished, such as limiting the valve, or setting other variables in the PLC As far as Honeywell's Profit Loop, I do like where manufactures are heading...helping us do our jobs better

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This depends on the quality of the system. The mathematics are tough if not impossible to beat if the system is designed if it is linear. When it isn't then people have an advantage because they know what tradeoffs to make. When I first derived the autotuning equations it was a shock to me. I thought I was doing so well for all these years and then my eyes were openned by the mathematics. Temperature control is a very slow process to there is plenty of time to estimate models on-the-fly. Motion controllers can't do that because they must close the loop at millisecond intervals or shorter instead of second intervals. A well tuned system doesn't need two set of parameters to keep from overshooting. What is necessary is to know when a lot of cold material is being inserted into the oven or whatever the disturbance is. A feed foward or disturbance rejection scheme is required because the extra mass will change the time constants and definately aborb more energy ( heat ). Most temperature controllers are PID only. There is no knowledge of the big picture. The problem with fuzzy logic is that is suffers from the same problems as PID and is FAR more complicated because there are more variables and ranges to screw around with. I have yet to see where Fuzzy logic improves anything. One still needs an integrator and a derivate input into the fuzzy controller. A fuzzy controller can not control temperature without the integrator.

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U can use Allen-Bradley Logix Family to implement a fuzzy controller... Just need the add-on FuzzyDesigner for RSLogix 5000 v.16... I hope it helps u!!!

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