3 Editing of Plants
In the Root Locus mode, you can edit your plant at the click of a
mouse. The following options are provided. The function of most of
these should be obvious:
-
Undo: Undo one change in the (open loop) plant.
- Add pole: Select the pole to be added by clicking on the
graphics window. If you select a point with nonzero real part, both
the point and its complex conjugate are added. That is, if G(s) is
the current open loop transfer function and you select a complex point
z, the new open loop plant will be
where z* denotes the complex conjugate of z.
- Remove pole: Click on the open loop pole that you want to
remove. If you click on a pole with nonzero real part, both the pole
and its complex conjugate are removed.
- Add zero: Similar to Add pole. Zero(s) are added to open loop
transfer function.
- Remove zero: Similar to Remove pole. Zero(s) are removed from
the open loop transfer function.
- Add cascade: You will be prompted to enter a transfer function
H(s)=a(s)/b(s). If G(s) is the current transfer function, it is
modified to
G(s)× H(s)
You will be prompted to ``accept'' this product. You can edit it if
you wish (to truncate some spurious decimal places etc). This command
is like a simultaneous addition of pole(s) and zero(s). However, in
this case you are required to enter these through the keyboard,
instead of using the mouse for the selection.
- Remove cascade: is like dividing G(s) by H(s), i.e. the open
loop plant is modified to
- Edit plant: The current plant is displayed in a dialogue
box. You can modify it directly by typing in the appropriate value.