Harmonic Drive RSF supermini Series User Manual

2-4 Duty Cycles
2-4
1
2
3
4
5
6
Selection of the RSF supermini Series
Example: 1
Select an actuator that best suits the following operating conditions:
Rotary speed: 140r/min
Load moment of inertia: 0.9×10
-3
kg･m
2
Since the load mechanism is mainly inertia, the load torque is negligibly small.
Acceleration/deceleration time is 0.03sec (30msec) or less.
(1) Compare these conditions with the [1-5 Specifications of RSF supermini actuators] (P1-4) and
temporarily select RSF-5B-50.
(2) Obtain J
A=1.83×10
-4
kg･m
2
, TM =0.9 N･m, KT=0.54 N･m/A, and IM =2.2A from [1-5 Specifications of
RSF supermini actuators] (P1-4).
(3) The friction torque of the actuator is T
F = 0.54×2.2-0.9 = 0.29 N･m from Formula (3) on the
previous page.
(4) Therefore, the shortest acceleration time and deceleration time can be obtained from Formula (1)
and Formula (2), as follows:
t
a = (0.183×10
-3
+0.9×10
-3
)×2×π/60×140/0.9 = 0.018 sec (18msec)
t
d = (0.183×10
-3
+0.9×10
-3
)×2×π/60×140/(0.9+2×0.29) = 0.011 s (11msec)
(5) Because the assumed acceleration/deceleration time is 0.03sec (30msec) or less, the temporarily
selected actuator can be used for acceleration/deceleration, based on the result of (4).
(6) If the calculation results of the acceleration/deceleration time do not fall within the desired time
range, examine them again as follows.
• Try to reduce the load moment of inertia.
• Re-examine the gear ratio and gear head model.
Calculating equivalent duty
During the selecting process of the RSF supermini series,
the temporal variability of torque and rotation speed need to
be taken into account. During acceleration or deceleration in
particular, a large amount of electricity flows to generate a
large amount of torque, resulting in a greater amount of
heat.
Using the following formula, calculate the duty: %ED when
the actuator is operated repeatedly in the drive pattern
shown to the right.
(4)
ta:
Acceleration time from speed 0 to N
［
s
］
td:
Deceleration time from speed N to 0
［
s
］
tr:
Operating time at a constant speed of N
［
s
］
t:
single cycle time in second
［
s
］
K
La
:
duty factor for acceleration time
KLr:
duty factor for driving time
K
Ld
:
duty factor for deceleration time
100
t
tKtKtK
ED%
dLdrLraLa
×
×+×+×
=
Ta, Tr, Td: output torque
ta
td
N
tr
Time
Speed
t: duty cycle
ts
Time
Torque
Td
ts: stop time

Harmonic Drive RSF supermini Series Specifications

General

Brand	Harmonic Drive
Model	RSF supermini Series
Category	Controller
Language	English