# Nyquist Plot generator

Description| How it worksThis app will generate the Nyquist Plot for a transfer function of the form (a + bs) e

^{-ts}/ (g + hs). In process control, Nyquist plots are used for analyzing the stability of controllers.

## Download

.xls file (142 KB) or .zip file (21 KB)## How to use

The use of this app is quite straightforward, simply key in the
values of a, b, g, h and t into the cells B6 through B10. Key in the
frequency range into the cells B13 and B14. Note that the units of
frequency is rad/time. The Nyquist plot is generated.

Lets say we wish to obtain the Nyquist plot of e^{-4s}/(1 +
2s), from 0.01 rad/s to 100 rad/s. We have

a = 1,

b = 0,

g =1,

h = 2 and

t = 4.

Key in these values and the range, the Nyquist plot is shown below.The following couple of images were obtained by running 1000
iterations. The first has a center at (0,0) and span of 4 while the
center of the second at (-1,0) and span of 2.

## Also See:

PID Loop SimulatorBode Plot Generator

Bode Plot using Complex Functions

PI Control of Integrating Process