Skip to main content
Engineering

You are not logged in. Your edit will be placed in a queue until it is peer reviewed.

We welcome edits that make the post easier to understand and more valuable for readers. Because community members review edits, please try to make the post substantially better than how you found it, for example, by fixing grammar or adding additional resources and hyperlinks.

4
  • $\begingroup$ Ahh so the issue is really about linear versus nonlinear, which makes sense. In linear systems, then you can write a transfer function and corresponding controller. I was trying to understand the details of both classical and modern/nonlinear systems and was missing that practical understanding. Thanks for your help. $\endgroup$
    – krishnab
    Commented Mar 30 at 16:14
  • $\begingroup$ Yeah, I will have to look for articles on designing classical controllers for nonlinear systems. I am not sure how efficient such a controller would be versus other types of controllers for nonlinear systems, but it is worth investigating. $\endgroup$
    – krishnab
    Commented Mar 30 at 16:19
  • 1
    $\begingroup$ There may be special choices of coordinates which hide the non linearity and allow one to derive a TF and make a PID controller. An example : rather than using angle of the pendulum as a state, some papers choose momentum or energy as the state. I don't know if such techniques exist for this system. $\endgroup$
    – AJN
    Commented Mar 30 at 16:20
  • 1
    $\begingroup$ "The oscillations of the the unstable system would grow (if designed properly) until the amplitude reaches 180 deg; i.e. up position." That wouldn't guarantee that the amplitude would reach 180 degrees, or that it would do so at a low enough velocity that the controller could "catch" the thing and keep it upright. The obverse, however, is certainly true: a controller that can erect an inverted pendulum would, when the pendulum is hanging, have a linearized model that would be unstable. $\endgroup$
    – TimWescott
    Commented Apr 1 at 3:43