Aerotech UNIDEX 600 Series, Руководство пользователя

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U600 User’s Guide AerTune
Version 1.4
Aerotech, Inc.
5-13
5.4.2. Excitation Parameters
In order to identify the necessary system parameters that the AutoTune algorithm needs
(calculate the servo loop gains), a multiple frequency sinusoidal test input is used to
excite the system. The following set up parameters are available:
5.4.2.1. Amplitude of Excitation in AutoTune
The Amplitude parameter sets the Peak-Peak envelope of the sinusoidal input. The system
will move about its starting position by +/- 0.5 * Amplitude. The Amplitude can be
displayed and entered either in raw machine counts or user units (inches/mm or degrees,
depending on the axes selected). The units can be changed by clicking on the counts or
user units button. Systems with high-resolution feedback devices will almost always
require the amplitude to be raised so that the system will move an adequate amount and
utilize a measurable amount of torque. In general, the AutoTune calculations will be more
accurate the larger the amplitude is, chosen within the constraints of the system.
If the Velocity Trap (VELTRAP) axis parameter is set to a non-zero value, AutoTune
will prevent System Excitation Parameters from being chosen that will violate the
Velocity Trap value.
5.4.2.2. Excitation Amplitude will exceed Velocity Trap Limit
The Amplitude of Excitation in AutoTune has been entered as a value that would cause
the VELTRAP axis parameter to be exceeded. The value will be re-adjusted to prevent
this from occurring.
5.4.2.3. Units: Inches/Degrees or Counts
The units of the Amplitude of Excitation in AutoTune may be entered in machine counts
or user units (inches or degrees), depending on the axis type. Click the desired radio
button.
5.4.2.4. Starting Frequency for Excitation in AutoTune
The Starting Frequency parameter sets the starting frequency of the sinusoid test input.
The units are in Hertz. The default value is usually a good starting point. In general, the
higher the frequency of the input, the more accurate the AutoTune calculations will be.
However, higher frequencies can cause high system velocities and high amplifier currents.
If the frequency is too high, over-current errors, velocity traps, or position errors may
result. In general, the starting frequency can be raised to 2.0 Hz, 2.5 Hz, or somewhat
higher depending on the system. Systems that have high inertia, small amplifiers, or small
motors may require the frequency to be reduced to 1 Hz or lower.
5.4.2.5. Ending Frequency for Excitation in AutoTune
The Ending Frequency for excitation in AutoTune will always be 4 times the Start
Frequency. Additionally, there will be an intermediate frequency generated 2 times the
Starting Frequency.