Siemens SINUMERIK 840D sl Function Manual page 372

G2: Velocities, setpoint / actual value systems, closed-loop control
7.6 Optimization of the control
Procedure
1. First optimize the position control loop as a proportional-action controller using the tools
described in the previous subsections.
2. Increase the tolerances of the following machine data while measurements are being taken
to determine the quality of the position control with proportional-plus-integral-action
controller:
– MD36020 $MA_POSITIONING_TIME
– MD36030 $MA_STANDSTILL_POS_TOL
– MD36040 $MA_STANDSTILL_DELAY_TIME
– MD36400 $MA_CONTOUR_TOL
3. Activate the position control loop as a proportional-plus-integral-action controller by setting
the following machine data:
MD32220 $MA_POSCTRL_INTEGR_ENABLE ; set value 1
MD32210 $MA_POSCTRL_INTEGR_TIME ; integral time [sec.]
Effect of integral time:
– T
– T
4. Find the right compromise for T
Note
T
can cause machine damage.
It is therefore recommended to set T
Use servo trace to trace the travel-in of an automatic program traveling to and from a target
position.
5. Set the servo trace to display the following:
– Following error
– Actual velocity
– Actual position
– Reference position
6. Reset the tolerance values in the following machine data to the required values, once the
optimum value for T
– MD36020 $MA_POSITIONING_TIME
– MD36030 $MA_STANDSTILL_POS_TOL
– MD36040 $MA_STANDSTILL_DELAY_TIME
– MD36400 $MA_CONTOUR_TOL
372
→ 0:
n
The control error is corrected quickly; however, the control loop can become instable.
→ ∞:
n
Effectiveness of the integral component is almost 0. Behavior of the controller like a
pure proportional controller.
must not be chosen too near the stability limit because the occurrence of an instability
n
has been identified:
n
between these two extreme cases for the application.
n
to no less than 1 s.
n
Function Manual, 01/2015, 6FC5397-0BP40-5BA2
Basic Functions