Examples For The Measuring Methods (Position Control Loop) - Siemens SINUMERIK 840D sl Commissioning Manual

10.5.5

Examples for the measuring methods (position control loop)

Measuring type: Reference frequency response
The reference frequency response measurement determines the transfer behavior of the
position controller in the frequency range. The position actual value is taken from the active
measuring system. The setpoint filters, control loop gain and feedforward control must be
parameterized so that resonance is avoided wherever possible over the entire frequency
range.
Measurement parameters:
● Amplitude
This parameter determines the magnitude of the test signal amplitude. It should be set to the
smallest possible value, e.g. 0.01 mm
● Bandwidth
The bandwidth parameter is used to set the analyzed frequency range. The larger this
value, the finer the frequency resolution and the longer the measurement time. The
maximum value is specified by the position controller cycle (T
Bandwidth
Example:
– Position controller cycle: 2 ms
– Bandwidth
● Averaging
The accuracy of the measurement and in turn the measurement duration increase with this
value. A value of 4 is normally adequate.
● Settling time
This value represents the delay between recording of the measured data and injection of the
test setpoint and offset. A value of between 0.2 s and 1 s is recommended. Do not set too
low a value for the settling times or the frequency response and phase diagrams will be
distorted.
● Offset
The measurement requires a speed offset of a few motor revolutions per minute. The offset
must be set such that no speed zero crossings occur at the set amplitude, and that the axis
continually moves in one direction.
Measuring type: Setpoint step and setpoint ramp
The transient and the positioning response of the position control in the time domain, and in
particular the effect of setpoint filters, can be assessed with the step and ramp excitation
functions.
Setpoint step:
To avoid overloading the machine mechanical system, for the "Setpoint step" measuring type,
the step amplitude is limited to the following value:
MD32000 $MA_MAX_AX_VELO (maximum axis velocity)
Setpoint ramp:
CNC Commissioning: NC, PLC, Drive
Commissioning Manual, 12/2019, A5E48312804B AA
[Hz] = 1 / (2 * T
max position controller
= 1 / (2 * 2*10 ) = 250 Hz
-3
max
10.5 Measuring functions (manual tuning)
position controller
[s])
Drive tuning
):
327