User`s manual

D-4 Motion Mate™ DSM314 for Series 90™-30 PLCs User's Manual – January 2001 GFK-1742A
D
Tuning a GE Fanuc Digital Servo Drive
The following pages provide you with an introduction to the basics required for tuning a GE
Fanuc Digital servo drive. This introduction shows one method for tuning a servo drive. The
method will not work in all applications, and you should modify the approach based on the
application. In order to display and measure the necessary signal waveforms, the DSM314 analog
outputs must be connected to an oscilloscope. Without an oscilloscope to measure the signals,
tuning the servo drive with the following approach will not be possible. The
Select Analog
Output Mode
%AQ command (47h) is used to select the data that is sent to the analog outputs
during servo tuning. Refer to Chapter 5 for a discussion of this %AQ command.
Tuning Requirements
The module has three main parameters that are adjusted during tuning. The parameters are the
Position Loop Time Constant
,
Velocity Feed Forward Gain
,
and
Velocity Loop Gain
.
The
Position Loop Integrator Time Constant
gives the position loop an additional degree of freedom
but in typical applications is not required.
The approach to tuning the control loops is to tune the inner control loops first. In this example,
the inner control loop that requires tuning is the velocity loop. As shown in the figure below, the
position loop is the outer loop and sends velocity commands to the velocity loop.
Torque/
Flux
Controller
Servo
Amp
Position
to
Velocity
Velocity
Control
Encoder
Interface
Position
Control
Path
Planning
Motor
Velocity
Command
Torque
Command
Position
Command
Figure D-1. Control Loops Block Diagram