G2: Velocities, setpoint / actual value systems, closed-loop control
7.6 Optimization of the control
Basic Functions
382 Function Manual, 09/2011, 6FC5397-0BP40-2BA0
MD32810 fine adjustment
Experience has shown that the initial value is only modified slightly during fine adjustment, typically by adding or
deducting 0.25 ms.
For example, if the initial value is 1.5 ms, the optimum value calculated manually is usually within the range 1.25
ms to 1.75 ms.
In the case of axes equipped with direct measuring systems (load encoders) and strong elasticity, you may
possibly accept small overshoots of some micrometers.
These can be reduced with the help of the position setpoint filter for dynamic response adaptation (MD32910
$MA_DYN_MATCH_TIME) and for jerk (MD32410 $MA_AX_JERK_TIME), which also reduces the axis speed.
Identical axis data within an interpolation group
All the axes within an interpolation group should have identical settings in the following data:
MD32200 $MA_POSCTRL_GAIN (adapted using MD32910)
MD32620 $MA_FFW_MODE
MD32610 $MA_VELO_FFW_WEIGHT
MD32810 $MA_EQUIV_SPEEDCTRL_TIME (or MD32800 $MA_EQUIV_CURRCTRL_TIME) (dependent on the
mechanical system and drive)
MD32400 $MA_AX_JERK_ENABLE
MD32402 $MA_AX_JERK_MODE
MD32410 $MA_AX_JERK_TIME
The servo gain display (K
V
) in the axis service screen form is used for checking.
Unequal axis data of an interpolation group
If identical values are not possible for the above data, the following machine data can be used to make an
adjustment:
MD32910 $MA_DYN_MATCH_TIME
This allows the same servo gain value (K
V
) to be displayed.
Different servo gain display values (K
V
) usually point to the following:
• The gear ratios do not match in one or several axes.
• The feedforward control setting data do not match.
Setting the equivalent time constant of the current control loop
MD32800 Equivalent time constant current control loop for precontrol
The same rules and recommendations apply to setting the time constant of the current control loop as to the
speed feedforward control.
However, activation of the torque feedforward control filter with:
MD32620 $MA_FFW_MODE = 4
must, for the purposes of setting the time constant with
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