
B-65150E/04 4. SERVO FUNCTION DETAILS
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(3) Control block diagram
Fig. 4.5.1 is a control block diagram
Fig. 4.5.1 Position loop block diagram that includes machine speed feedback function
As shown in Fig. 4.5.1, this function corrects the torque command by
multiplying the machine speed by machine velocity feedback gain, α,
as shown by the bold line. When α = 1, the torque command is
corrected equally by the motor speed and the machine speed.
(4) Adding the normalization function
(a) Overview
If an arc is drawn with the machine speed feedback function
enabled, the arc may be elongated in the direction parallel to the
axis to which the machine speed feedback function is applied. To
solve this problem, the machine speed feedback function was
improved.
(b) Explanation
The current machine speed feedback configuration is as
shown left figure. Assuming that the motor speed
feedback is much the same as the speed feedback at the
tip of the machine, the speed feedback for the
proportional term is (1 + α) times the motor speed
feedback. This causes a conflict to the weight of the
VCMD.
So, the proportional term speed feedback is divided by
(1 + α) to eliminate the conflict.
PK1V/s + PK2V
1/(Jm • s)
1/(JL • s)
+
−
Spring coupling
PK1V: velocity loop integral gain
PK2V: velocity loop proportional gain
α
: machine speed feedback gain
VCMD +
−
MCMD +
−
Kp
PK2V ×
α
1/s
Machine
Motor
TCMD
Speed feedback
Position feedback
+
Machine speed
Motor
Machine
α
Motor speed
feedback
+
+
Speed feedback for
proportional terms
Speed feedback
at the tip of the
machine