Position Controller - Siemens SINUMERIK 840Di sl Commissioning Manual

11.5.14

Position controller

Control loops
The closed-loop control of a machine axis consists of the cascaded closed-loop control
circuits of current controller, speed controller and position controller.
Figure 11-16 Control loops
Traversing direction
If the axis does not traverse into the desired direction, the appropriate adaptation is made in
the following machine data:
● MD32100 $MA_AX_MOTION_DIR (travel direction)
The value "-1" reverses the direction of motion.
Control direction
If the control direction of the position measuring system is incorrect, it can be adjusted with
the following machine data:
● MD32110 $MA_ENC_FEEDBACK_POL (sign of actual value)
Servo gain
To obtain high contour accuracy, a high loop gain (Kv factor) of the position controller is
required. However, an excessively high Kv factor causes overshoot, instability and
impermissibly high machine loads.
The maximum permissible Kv factor is dependent on the dynamic response of the drive and
the mechanical system of the machine.
If "0" is entered for the loop gain factor, the position controller will be disconnected.
Manual
Commissioning Manual, 05/2008, 6FC5397–4CP10–4BA0
NC Commissioning with HMI Advanced
11.5 Axes and spindles
413