PID advanced not working after switching on and off

[philipp.n]

Hello there,

I am trying to simulate the control of an inverted pendulum with the simulation module and the PID toolkit and actually the model runs fine with one problem remaining. When I switch the PID to manual mode and then back to automatic the controller is not able to balance the pendulum to 0 degree like he has done when I started the program.

I have added the project maybe someone has an idea how to get this working because I am not that familiar with these toolkits.

Thanks in advance and best regards

Philipp

PS: I am using two different models in the project but both have the same problem.

[Barp]

Philip,

You zip file is missing "Pendulum sub.vi" could you send that also?

Thanks,

Barp

Control Design and Simulation Group

National Instruments

[philipp.n]

Hi Barp,

here it is, hope this is the only one missing

Cheers

Philipp

[Barp]

Philipp,

The problem that you have is actually a common problem for those who try to use PID for this problem.

When you try to use only one PID to control angle, the controller is able to keep it up right in the beginning. However, when you switch the controller on and off (going from automatic to manual), this perturbance will make the cart to move to one direction (adding momentum to it) and the PID will try to bring it back to the center, but it will be far away from the center. If you give time, it eventually will bring back to 0.

In this link below, you have more information about this problem and, most important, tells you that for practical controllers, you can't use static PID for this problem. Maybe you could use gain scheduling PID or cascade PID to also control position also. In general, the LQR controller works pretty well for this problem.

http://www.engin.umich.edu/group/ctm/examples/pend/invPID.html

Anyway, let me know if that answer your question.

Barp - Control & Simulation Group - National Instruments

[philipp.n]

Hi Barp,

thanks for the fast reply I will try using the controllers you mentioned down below to get it working.

Thanks and have a nice day

Philipp

[Gsteen]

Hello Philipp.

I am working on an inverted pendulum simulatror.
I look at the one you put here and I got some good tips.
There are some things i cant figure out, because i cant mach my math formulas to you simultator.
Could i have a look at your equations?

Best regards
Gøran Steen

[maWence]

Hi Philipp, I'm having problem loading pendulum simulation files you uploaded here.... LabVIEW seems to be missing SIM Chop Build Call Chain.vi file.... among others.... I have version 8.5, so if you can somehow help me, it would be GREAT!!!! Thanx in advance :) Marko

[philipp.n]

Hello maWence,

I haven´t worked with the project for more then a year now. Normally it should work when you download the zip file and the additional subvi.

don´t think that i password protected it, but you will need the simulation toolkit.

cheers philipp