What is a plant?

A plant is the system under control. Many plants in the motion control world are permanent magnet motors with current drives.

You can make a theoretical model of the plant, but it is often easier and more accurate to measure the plant under control. All of the examples shown in the Frequency Shaping Tuning section use the Bode Tool to acquire plant data.

What makes a good plant model?
You would like the data to be free from errors and noise. Realistically, this means that you want to keep noise low enough to identify key features of the response and accurate enough that the errors in the data are less than the variation of plant that you can tolerate. For instance, if you can only tolerate a 20% change in motor torque constant, then a 30% error would be unacceptable.