ElmoMC SimplIQ Digital Servo Drives-Bell Getting Started - Manual (Page 53)

The SimplIQ for Steppers Getting Started & Tuning and Commissioning Guide
MAN-BELGS (Ver. 1.1)
53
4.2.1 Identification and Uncertainty
The identification produces a frequency response. A frequency response is a
characteristic of a linear, time invariant plant. We take frequency response not
because the plant is really linear and time invariant; but because all the
established control design theory deals with plants having frequency responses.
Knowing very well the limitations of frequency responses, the DFT tuner
identifies many frequency responses instead of one. Each frequency response
describes the plant linearized about a different working point.
After this process, you will have many measured values for the amplitude/phase
of the plant at any given frequency. This set of values forms an "uncertainty set"
for the frequency.
Later, the Conductor will design a controller that optimizes the response to the
entire uncertainty set. This is much better than traditional methods that can only
consider one plant model at a time.
When the Conductor presents the identification result it normally shows one
nominal transfer function. This is because handling a multitude of transfer
functions is very complex.
Identification is an involved process, as it is nonlinear and noisy.
The Conductor is based on many years of trials and collecting data from actual
motion systems.
4.2.2 Identification Results Management
The Conductor stores the identification results in files with the .idn extension.
An identification file stores a list of frequencies and the associated amplitude and
phase values of the plant transfer function.
You can keep several .idn files, each describing the plant with different working
conditions.
Identification file maintenance is from the window that opens by clicking
Identify in the Motion tab of the Conductor.