Speed Loop Pid Changeover Control - Mitsubishi Electric MDS-D-SPJ3 Specification Manual

3-2-4 Speed loop PID changeover control

This function is used under full-closed loop control. Normally, machine-end position tracking delays
compared with the motor-end position.
Under full-closed position loop control, machine-end position is used for position feedback. Therefore, the
motor-end position tends to advance too much, which may cause overshooting of the machine-end position.
This function can suppress the generation of overshoot by adding the D (delay) control to the speed control,
which is normally controlled with PI (proportional integral), in order to weaken the PI control after the position
droop becomes 0.
3-2-5 Disturbance torque observer
The effect caused by disturbance, frictional resistance or torsion vibration during cutting can be reduced by
estimating the disturbance torque and compensating it.
3-2-6 Smooth High Gain control (SHG control)
A high-response control and smooth control (reduced impact on machine) were conventionally conflicting
elements; however, SHG control enables the two elements to function simultaneously by controlling the
motor torque (current FB) with an ideal waveform during acceleration/deceleration.
3-2-7 High-speed synchronous tapping control (OMR-DD control)
Servo drive unit detects the spindle position, and compensates the synchronization errors. This control
enables more accurate tapping than the previous.
Spindle speed
(r/min)
4000
3000
2000
1000
0
−1000
−2000
−3000
−4000
Speed
Conventional control
Position loop step response
Spindle speed
Servo/Spindle
synchronous error
0 0.5 1 1.5 2 2.5 3 3.5
(sec)
〈Without OMR-DD control〉
MDS-D-SVJ3/SPJ3 Series Specifications Manual
3-2 Servo/Spindle control functions
SHG control
Time
Spindle speed
(r/min)
4000
3000
Spindle speed
2000
1000
0
−1000
Servo/Spindle
−2000
synchronous error
−3000
−4000
0 0.5 1 1.5 2 2.5
With OMR-DD control
〈
3 3.5
(sec)
〉
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