inverted pendulum

I need help.I'm in my final year of a degree in mechatronics and the project I have been given is to design a control system for an inverted pendulum using a PLC.The pendulum itself is one that is already in the college ;its the Bytronic PCS1 but it is controlled by a computer programme.I have to use a PLC to control the pendulum.I have no idea how to do this as I only used a PLC for the first time about 2 months ago.My supervisor mentioned using a PID algorithm.What is this and how would I implement it?

any help would be appreciated

Your in your final year of a degree program that is supposed to cover mechanical, electrical, and software engineering and you've never heard of PID?

Regardless since you seem to need some help...
PID = Proportional Integral Derivative
It is a very common control algorithm used to control real world variables.

See this link for more information about PID.
http://www.jashaw.com/pid/description.htm

Good luck with this one.

Does the source code for the program you say is controlling it now not have an algorithim to control it? Can you get to the source code? If it a matter of porting the program to a plc based system, that should be easy. If not, it will probably require a lot of math.

Gearoid,

Perform a search on this site for PID, and specifically for some posts by Ron Beaufort on PIDs. He has posted some excellent tutorials on the subject. Once you have looked at that, I'm sure you will be back with some more questions, but the questions won't be 'what is a PID?"


A little more info would be helpful also: What make/model of PLC are you using? Every model of PLC implements PID a little differently, but the basic operation underlying it as a control method is the same.

A google on "Bytronic PCS1" turned up some interesting information, including a picture of pendulum system and some PDFs that show block diagrams of control schemes.

Typically a stand-alone PID is not very well suited to a problem like the inverted pendelum. The inverted pendelum is not a linear process so a single set of gains won't be able to maintain control of the pendelum.

If you know enough about digital controller design you may be able to implement a digital controller directly in the plc using standard math instructions. I really can't help you much there; that's kind of over my head. If I remember right the controllers that work well for this are feed-forward dominated and are based on a relatively thorough system model.

There are a few people on this forum that may be able to help much more than me. Stay tuned.

Keith