User guide

Chapter 3. Basic Operation Setup 99
Tuning
For an overview of servo
control terminology and
techniques, refer to the
Servo Tuner User Guide ,
or to your product's
installation guide.
To assure optimum performance and , you should tune your servo system. The goal of the
tuning process is to define the gain settings, servo performance, and feedback setup (see
command list below) that you can incorporate into your application program. (Typically, these
commands are placed into a setup program – see examples on page 103).
We recommend using Servo Tuner™, a graphical tuning software tool (see note below). If you
prefer a more empirical method, refer to the procedures in your 6000 product's installation guide.
Servo Tuning Software Available
To effectively tune your 6000 servo controller (and any velocity drives you may be using),
use the interactive tuning features in the Servo Tuner™. It greatly improves your efficiency
and gives you powerful graphical tools to measure the performance of the system.
Servo Tuner is included as an integral element of Motion Builder™, an optional icon-based
programming tool. Servo Tuner is also available as an optional add-on module to Motion
Architect (it does not automatically come with the basic Motion Architect software package).
Instructions for using Servo Tuner are provided in the Servo Tuner User Guide and in
Motion Builder's online Help system and Motion Builder Startup Guide & Tutorial .
To order Motion Builder or the Servo Tuner add-on module to Motion Architect, contact your
local Automation Technology Center (ATC) or distributor.
0.000 205.975
0.000 205.975
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Axis 1 Comm Pos (counts) Axis 1 Comm Pos (counts)
Time (millisec)
Time (millisec)
Tuning-Related Commands (see 6000 Series Software Reference or the Servo Tuner User Guide for details)
Tuning Gains:
SGP * ............ Sets the proportional gain in the PIV&F servo algorithm.
SGI * ............ Sets the integral gain in the PIV&F servo algorithm.
SGV * ............ Sets the velocity gain in the PIV&F servo algorithm.
SGAF *.......... Sets the acceleration feedforward gain in the PIV&F
a
algorithm.
SGVF *.......... Sets the velocity feedforward gain in the PIV&F
v
algorithm.
SGILIM....... Sets a limit on the correctional control signal that results from the
integral gain action trying to compensate for a position error that
persists too long.
SGENB.......... Enables a previously-saved set of PIV&F gains. A set of gains
(specific to the current feedback source selected with the SFB
command) is saved using the SGSET command.
SGSET.......... Saves the presently-defined set of PIV&F gains as a gain set
(specific to the current feedback source on each axis). Up to 5
gain sets can be saved and enabled at any point in a move profile,
allowing different gains at different points in the profile.
* 6270 only: Negative gains (SGPN, SGIN, SGVN, SGAFN, SGVFN)
are automatically applied when the position error is negative.
Servo Performance:
INDAX.......... Selects the number of available axes to use (see page 79).
SSFR............ Sets the ratio between the update rate of the move trajectory and
the update rate of the servo action. Affects the servo sampling
update , the motion trajectory update , and the system update .
Feedback Setup:
SFB.............. Selects the servo feedback device. Options
(depending on the product) are: encoder, resolver,
ANI input, or LDT. IMPORTANT: Parameters for
scaling, tuning gains, max. position error (SMPER),
and position offset (PSET) are specific to the
feedback device selected (with the SFB command) at
the time the parameters are entered (see
programming examples on page 103).
ERES............ Encoder resolution (also selects the resolution for a
resolver).
LDTRES....... (6270 only) Sets the LDT resolution.
LDTGRD....... (6270 only) Sets the LDT gradient.
LDTUPD....... (6270 only) Selects the rate at which the LDT position
is sampled.
SMPER......... Sets the maximum allowable error between the
commanded position and the actual position as
measured by the feedback device. If the error
exceeds this limit, the controller activates the
Shutdown output and sets the DAC output to zero
(plus any SOFFS offset). If there is no offset, the
motor will freewheel to a stop. You can enable the
ERROR command to continually check for this error
condition (ERROR.12-1), and when it occurs to
branch to a programmed response defined in the
ERRORP program.