Siemens SINUMERIK 840Di Manual page 425

06.03
Measurement
parameters:
Setpoint and
disturbance
setpoint change
 Siemens AG, 2003. All rights reserved
SINUMERIK 840Di Manual (HBI) – 06.03 Edition
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 measure-
ment time. The maximum value is given by the position control cycle (T
).
controller
Bandwidth [ Hz ] = 1 / (2 * T
max
Example: Position controller cycle: 2msec
Bandwidth = 1 / (2 * 2*10
max
Averaging
The accuracy of the measurement, but the measurement duration, too, will in-
crease with this value. A value of 20 is normally suitable.
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 and 1sec is rec-
ommended. 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 slight speed offset of a few motor revolutions per
minute. The offset must be set to a higher value than the amplitude.
S
The Offset is run up using an acceleration ramp.
S
The acceleration value is defined for one
axis: check MD 32300: MAX_AX_ACCEL
spindle: check MD 35200: GEAR_STEP_SPEEDCTRL_ACCEL
MD 35210: GEAR_STEP_POSCTRL_ACCEL
S
The following applies:
S
The actual measuring function becomes active only when the offset value is
reached.
The transient response (command behavior or disturbance characteristic) of the
speed control in the time range can be assessed using the step excitation. The
test signal is connected to the speed controller output for recording of the re-
sponse to disturbances.
Amplitude
This parameter determines the height of the preset setpoint step change or dis-
turbance change.
Measuring time
This parameter determines the recorded time range (maximum 2048 x speed
controller cycles).
13 Drive Optimization using HMI Advanced
13.4 Frequency response measurement
position controller
–3
) = 250Hz
Acceleration value = 0, no ramp
Acceleration value > 0, ramp active
position
[ sec ])
13-425