HEIDENHAIN TNC 335 Technical Manual - Manual (Page 148)

8/95
TNC 360 3 Servo Positioning of the NC Axes 4-51
3 Servo Positioning of the NC Axes
This section describes all the control functions which are important for the control and monitoring of
the NC axes.
Further parameters for the NC axes can be found under "Machine axes."
The control of the spindle (S axis) is described in section "Spindle."
3.1 The position control loop of an NC machine
In CNC machines the servo control is normally implemented as a cascade control (see following
block diagram).
The motor speed control and the current control (both in the drive amplifier) are integrated into the
servo position control (CNC control). The servo controlled system consists of the motor and machine
slide.
A
c
tual
rpm A
c
tual
position
Linear/
angle
encoder
Speed
controller
Position
controller
Current
regulator
Drive Tacho
Nom.
cur.
Nom.
pos.
Servo
lag
Nom.
rpm
A
c
tual
cur
rent
A
c
tual
position A
c
tual
rpm
CNC Control Servo amplifier Machine
Block diagram of the position control loop, here as a cascade control