Zeros and Poles

Navigation:  Toolboxes > Control Toolbox > Controller Design Editor >

Zeros and Poles

Previous pageReturn to chapter overviewNext page

A continuous-time SISO transfer function can described by the transfer function:

 

gain1

 

This transfer function can be rewritten in pole zero notation with

 

gain2

where pi .. p1 are the poles and zi .. z1 are the zeros and KRL is the Root Locus Gain of the system. The same can be done for a discrete-time SISO transfer function.

ZerosPoles

You can enter zeros and poles by selecting the Zeros & Poles button and clicking the Edit button.

ZerosPolesEdit

 

This opens an editor in which you can enter the real and imaginary parts of the zeros and poles as well as the Root Locus Gain. If preferred, you can also enter the System Gain. Note that zeros and poles always have conjugate when the imaginary part is non-zero. I.e. when you enter a pole with imaginary part 0.5 an extra pole is added with imaginary part -0.5.

Output Delay

To inspect the effects of time delay in your model, you can add output delay. The result will be visible in the various plots that you can show of a linear system. The unit of the output delay is seconds.

Discrete Sample Time

If you want to transfer a linear system from continuous time to discrete time directly (i.e. replace the s by a z), select Discrete Sample time and fill in the sample time value. You can also transfer back directly by deselecting Discrete Sample time.

Commands

Add/Delete: Add or delete selected poles or zeros.
Help: Open the help file.
Apply: Apply the current changes of the system, recalculate each plot that is active (step, Bode, Nyquist, Nichols, pole zero).
OK:  Apply the current changes of the system, recalculate each plot that is active (step, Bode, Nyquist, Nichols, pole zero) and close the editor.
Cancel: Do not apply any changes to the system and close the editor.