GSK DA98B - 9.4 Servo and orientation controller computation

GSK CNC Equipment Co., Ltd.
72
K
S
Open loop gain of the system，usually 8s
-1
- 25s
-1
; for MC K
S
＝ 20s
-1
；
M
L
—— Load torque（N•m）.
If M is less than the max. torque M
max
of servo motor, the motor speed can be
increased or decreased by the time constant used.
2） Preliminary confirmation of mechanical gear ratio
Calculate the max. mechanical reduction ratio by the highest speed and
highest speed of motor required and collate it to the min. orientation unit with
the min. revolution unit and the reduction ratio. If the requirement of the
orientation precision is very high, increase the mechanical reduction ratio (the
actual highest speed is lowered) or choose a faster motor.
3） Check of inertia and torque
Convert the inertia and torque of load to the motor shaft by mechanical
reduction ratio, and the inertia converted should be less than quintuple of the
motor rotor inertia. And the load torque converted and the effective torque
should be less than the rated torque of motor. If the requirement above can’t be
met, increment of mechanical reduction ratio (the actual highest speed is
lowered) or a higher capacity motor may be employed.
9.2 Electronic gear ratio
Refer to chapter 4 (Section 4.2 Parameter function), chapter 6 (Section 6.2.5
Orientation control run) for the significance and adjustment of electronic gear ratio.
In the orientation control mode, the actual speed of load is:
Instruction pulse speed×G ×mechanical reduction ratio.
In the orientation control mode, the actual min. displacement of load is:
Min. instruction pulse stroke×G ×mechanical reduction ratio
9.3 Stop characteristic
Lag pulse is defined to the difference between the instruction pulse and feedback
pulse when the servo motor is controlled by pulse strings in orientation control mode. The
difference is accumulated in the orientation deviation counter, and its relationship with the
instruction pulse frequency, the electronic gear ratio and the orientation proportional gain
If the electronic
g
ear ratio G is not 1, there may be a remainder when
executin
g
the division for
g
ear ratio, which may lead to position deviation
and the max. deviation is the min. revolution amount of the motor (min.
resolution).