YASKAWA E Series Product Manual page 41

2.1 Selecting the Servomotor Capacity
2.1.2 Capacity Selection Example for a Rotary Servomotor: For Position Control
9.
Verification of the Provisionally Selected Servomotor
• Verifica-
tion of
required
acceler-
ation
torque:
• Verifica-
tion of
required
deceler-
ation
torque:
• Verifica-
tion of
effective
torque
value:
It has been verified that the provisionally selected Servomotor is applicable in terms of capacity.
Position control is considered next.
10.
Positioning Resolution
The electrical stopping precision
The ball screw lead P
following formula.
Number of pulses per rotation (pulses)
The number of pulses per motor rotation is less than the encoder resolution (pulses/rev), so the provi-
sionally selected motor can be used.
11.
Reference Pulse Frequency
The load speed υL is 15 m/min, or 1,000 × 15/60 mm/s and the positioning resolution (travel distance
per pulse) is 0.01 mm/pulse, so the reference pulse frequency is calculated with the following for-
mula.
vs =
The reference pulse frequency is less than the maximum input pulse frequency,* so the provisionally
selected Servomotor can be used.
*Refer to the specifications in the SERVOPACK manual for the maximum input pulse frequency.
It has been verified that the provisionally selected Servomotor is applicable for position control.
2-6
2πn M (J M + J L )
T P =
60ta
≈ 0.552 (N m) < Maximum instantaneous torque...Satisfactory
2πn M (J M + J L )
T S =
60td
≈ 0.274 (N m) < Maximum instantaneous torque...Satisfactory
2
T P ta +
Trms =
≈ 0.192 (N m) < Rated torque...Satisfactory
is 0.005 m, so the number of pulses per motor rotation is calculated with the
B
1,000 υ
1,000 × 15
L
= = 25,000 (pps)
60 × 60 × 0.01
Δ
2π × 3,000 × (0.0659 + 1.25) × 10
+ T L =
60 × 0.1
2π × 3,000 × (0.0659 + 1.25) × 10
− T L =
60 × 0.1
2 2
T L tc + Ts td
(0.552)
=
t
δ
is ±0.01 mm, so the positioning resolution Δ is 0.01 mm.
P B
5 mm/rev
= = = 500 (P/rev) <
Δ
0.01 mm
-4
+ 0.139
-4
− 0.139
× 0.1 + (0.139) × 0.9 + (0.274)
2 2
1.5
Encoder resolution (16,777,216 (pulses/rev))
× 0.1
2