Components of Positioning Control and their Roles Drive mechanism
3 - 12
MITSUBISHI ELECTRIC
Useful equations
To define the system illustrated above, 욼
l
and v
0
need to be determined using a series of equations.
The speed of the moving part (v
0
) is constrained by the mechanical gearing system between the servo
motor and moving part, the pitch of the ball screw, and the specification of the motor as shown
through the following two formulas.
Transfer distance per rotation of motor:
Number of rotations of motor during quick feed:
If N
0
does not exceed the rated speed of the motor, this means that the servo system can be used for
the application. In order to determine if the positioning controller is applicable, the command pulse
frequency during quick feed (f
0
) should be checked to verify it does not exceed the maximum
allowable frequency setting for the "maximum speed" parameter setting of the controller.
Transfer distance per pulse:
Command pulse frequency during quick feed:
During the above process, the Electronic gear ratio (often "CMX/CDV" for Mitsubishi servos) and
Speed reduction ratio can be adjusted to fit the application’s needs.
In each of the absolute and incremental positioning methods, the entire movement distance of the
machine should not exceed the maximum allowable pulse output number from the positioning
controller.
P
B
1
n
Δ
S
=
=
N
0
Δ
S
v
0
Rated number of
rotations of
servo motor
rev
min
=
Δ
Δ
S
P
f
l
(Electronic gear ratio)
mm
PLS
S
=
Δ
S
Δ
f
0
N
0
60
1
l
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