PID - A simple position control simulator

[croakus]

Not too long...

Peter,
It took 5-10 minutes and was relatively easy. It was made so in the fact that a change is instantaneous and you gave us the target - to get the ISE below 59. I threw out numbers at first, watching the ISE, and then tweeked it via the graph. It was a fun challenge, made so by not having to stay hours past quitting time or worry about trashing thousands of dollars of equipment.

Thanks for taking the time to do this. Good coverage of this subject in school appears to be lacking for a lot of people.

 

[Peter Nachtwey]

Re: poles

Peter what do you mean by 3 real poles and what is radians per second?

A single real pole is like a low pass filter the has been posted on this site many times

y=K*y(n-1)+(1-K)*x(n-1)

A two pole filter is just another filter on the filter.

z=K*z(n-1)+(1-K)*y

1 to 4 Real Poles

The link is to another spread sheet that shows the response of one to four pole filter. The thing to notice is that a single pole filter is much different from the many pole filters. The slope of the response a single pole filter starts steep and then always decreases.
Multi-pole filters will start out not as steep but will get steeper before becomming more gradual. It is hard to tell the multiple pole filers apart but you should be able to tell the difference between a single pole or double pole. Knowing how your system responds to a step input is the first step in knowing how to tune your system.

Other things you might try is modifying the input signal to see how the different filters respond.

Why does the first filter above use x(n-1) instead of x. Remember, we are simulating the response of a physical system.

One more thing, if you look the response of the 4 pole filter you can see that it doesn't look like the filter is responding at first. Some people mistakenly call this dead time. It is sometime very hard to tell the difference between real dead time and a multiple pole system.

 

[swaminathan]

I wonder the link is not Accessable

swaminathan

 

[Paullys50]

I wonder the link is not Accessable

swaminathan

The thread is almost 3 years old, chances are it's been gone for awhile. But being a rookie in the PLC world it would be nice to check this out. So Peter if you're listening, can you re-host?

 

[Peter Nachtwey]

I was able to find all the files but the filter HTML file

It will take time to regenerate that one from Mathcad.
The spread sheets and the power point links should work now.

There is a new group of people here now. Maybe they would like to take up the challenge. I made these excel worksheets because there were people giving advice on how to tune another persons system when the person giving advice knew less about the system than the person asking for help. Every week for about 5 weeks I made a new Excel spread sheet that had a different type of system. This point was to show how each system is different so just because you have tuned one system doesn't mean you can tune them all. Unfortunately there are still 'engineers' that haven't learned that. There are still people giving advice without knowing the first thing about the other persons system.