Choice of F_Q transfer function in Q-design controller

Given a plant's transfer function, G_o(s), how would one be able to choose the choice of a controller using Q-design method, where Q(s) F_(s)*G_o^(s), where G_o^(s) is the inverted signal of the
plant? More specifically, how would one justify whether to use first, second, or third-order model for F_(s)? Thanks in advance
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
ssylee wrote:

Practically or academically? (Where have I used that before?)
I'm not sure what you mean by the order of the model, but I assume that you're constraining the behavior of your F_(s) to keep the plant drive within bounds -- so do some analysis on the plant transfer function, or try things out in simulation, and see what works best. You want the simplest system that will still attain your goals.
--
Tim Wescott
Control system and signal processing consulting
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

It isn't clear what you are really trying to do? One could do many things. if the controller is 1/G_o(s) then F(s) could be a low pass filter to reduce output noise. Why not simply make F((s) a constant to increase the gain and get the closed loop control closer to unity?
You need to give a precise example as the question is vague. Why bother with Q design in the first place is a better question?
Peter Nachtwey
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.