Siemens SINUMERIK 840D sl Function Manual page 457

2.5 Optimization of the control
2.5.1 Position controller: injection of positional deviation
Application
The stability and positioning response of axes with a low natural frequency (up to approx. 20
Hz) and a mechanical design capable of generating oscillations is improved by active
oscillation damping with simultaneous use of the feedforward control.
To illustrate this, the difference in position between two measuring systems is generated
and injected as an additional current setpoint for the feedforward control, according to the
weighting of machine data:
MD32950 $MA_POSCTRL_DAMPING
.
The function is used predominantly for axes with strong tendency to vibrate.
Functionality
The positional deviation is injected in the NC in the position controller cycle of the higher-
level position control loop in the NC.
The difference in position between a direct and an indirect measuring system is generated
and injected as an additional current setpoint, depending on the weighting of machine data:
MD32950 $MA_POSCTRL_DAMPING.
Direct measuring system:
MD31040 $MA_ENC_IS_DIRECT[1]=1
The encoder for position actual-value acquisition is connected directly to the machining
process of the machine (load encoder).
Indirect measuring system:
MD31040 $MA_ENC_IS_DIRECT[0]=0
The encoder for position actual-value acquisition is located on the motor (motor encoder).
Basic logic functions: Velocities, Setpoint/Actual Value Systems, Closed-Loop Control (G2)
Function Manual, 11/2006, 6FC5397-0BP10-2BA0
Detailed description
2.5 Optimization of the control
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