tension controll


Thread Starter

Double 3

I want to control tension by the PID instruction of OMRON PLC(C200HE).But I don't know how to tune
it. Can anybody who have experience tell me how to get the perfect P¡¢I¡¢D.

thanks a lot!

Thomas Allen

I was just playing with PID controls for the first time, and once the smoke and mirrors are removed they are really not that bad.

First of all make sure that any goofs you make will not hurt anyone, because you probably will mess up before you get it just right.

You usually have two inputs and one output on the PID function. A set point, input, and an output. The set point will drive the output to make the input match the set point.

You have three "important" terms, P I D

P is the proportional. It is just a multiplier. The bigger the difference between the set point and the input the more it will affect the output.

I is the integral. This is the "Area under the Curve" term. A small difference between the input and the set point over a long time will give you a sizeable output, where a sine wave on the input will never give you an output from this term.

D is differential, or the rate of change. A large difference between the set point and the input that doesn’t move will have no affect on this term, but if the input or set point were to suddenly change the output would have a spike.

The last thing that you need to keep in mind is that the Controller needs to be ten times faster than the Controllee. That means that you need to guess at how fast you’re application can change. It sounds like a mass on a spring, if it is this rate is how fast it will oscillate.

Good luck, and play safe.

Thomas B. Bullock

Click on the BULL! luminary on the Control.com home page and you will find 2 tutorials regarding PID and servo controls.

Hopefully, these will help understand the basics.
Tom Bullock
[email protected]
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