Siemens sinumerik 840D sl Function Manual page 156

Detailed description
2.3 Start-up of gantry axes
• MD32420 $MA_JOG_AND_POS_JERK_ENABLE (basic position of axial jerk limitation)
• MD32430 $MA_JOG_AND_POS_MAX_JERK (axial jerk)
References:
/FB1/ Function Manual, Basic Functions, Velocities, Setpoint-Actual Value Systems, Closed-
Loop Control (G2)
Dynamics matching
The leading axis and the coupled axis must be capable of the same dynamic response to
setpoint changes. The same dynamic response means: The following errors are equal in
magnitude when the axes are operating at the same speed.
The dynamic response adaptation function in the setpoint branch makes it possible to obtain
an excellent match in the response to setpoint changes between axes, which have different
dynamic characteristics (control loops). The difference in equivalent time constants between
the dynamically "weakest" axis and the other axis in each case must be specified as the
dynamic response adaptation time constant.
Example
When the speed feedforward control is active, the dynamic response is primarily determined
by the equivalent time constant of the "slowest" speed control loop.
Leading axis:
MD32810 $MA_EQUIV_SPEEDCTRL_TIME [n] = 5ms (equivalent time constant speed
control loop for feedforward control)
Following axis:
MD32810 $MA_EQUIV_SPEEDCTRL_TIME [n] = 3ms
• Time constant of dynamic response adaptation for synchronized axis:
The dynamic response adaptation must be activated axially with the machine data:
MD32900 $MA_DYN_MATCH_ENABLE (dynamic response adaptation)
Check of dynamic response adaptation:
The following errors of the leading and synchronized axes must be equal in magnitude when
the axes are operating at the same speed!
For the purpose of fine tuning, it may be necessary to adjustservo gain factors or
feedforward control parameters slightly to achieve an optimum result.
Referencing gantry axes
The positions of the reference points of the leading and synchronized axes must first be set
to almost identical values.
To ensure that the synchronization compensatory motion of the gantry axes is not started
automatically, the gantry warning limit must be set to 0 at the first start-up before referencing:
MD37100 $MA_GANTRY_POS_TOL (gantry axis definition)
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MD32910 $MA_DYN_MATCH_TIME [n] = 5ms - 3ms = 2ms (time constant of dynamic
response adaptation)
Special functions: Gantry Axes (G1)
Function Manual, 11/2006, 6FC5397-2BP10-2BA0