Harmonic Drive FHA Mini Series, Руководство пользователя

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Chapter 2 Guidelines for sizing
FHA-mini
24
Chapter 2 Guidelines for sizing
2-1 Allowable load inertia
To achieve high accuracy performance,
select an FHA-C mini actuator wherein the
allowable moment of inertia (reference value)
is greater than the load inertia.
Refer to appendix 1 for the calculation of
moment inertia.
When selecting an actuator make certain that
the load inertia and the nominal speed are
less than the allowable values are that
indicated in the table below.
Actuator model
FHA-8C FHA-11C FHA-14C
-
30
-
50
-
100
-
30
-
50
-
100
-
30
-
50
-
100
Reduction ratio 1:30 1:50 1:100 1:30 1:50 1:100 1:30 1:50 1:100
Maximum speed r/min 200 120 60 200 120 60 200 120 60
Moment of inertia
of actuator
kg•m
2
0.0026 0.0074 0.029 0.0060 0.017 0.067 0.018 0.050 0.20
kgf•cm
･
s
2
0.027 0.075 0.30 0.061 0.17 0.68 0.18 0.51 2.0
Allowable moment
of inertia
kg•m
2
0.0078 0.022 0.087 0.018 0.051 0.20 0.054 0.15 0.60
kgf•cm•s
2
0.081 0.23 0.90 0.18 0.51 2.0 0.54 1.5 6.0
2-2 Variable load inertia
FHA-C mini series actuators include Harmonic Drive® gearing that has a high reduction ratio. Because
of this there are minimal effects of variable load inertias to the servo drive system. In comparison to
direct servo systems this benefit will drive the load with a better servo response.
For example, assume that the load inertia increases to N-times during its motion (for example, robot
arms). The effect of the variable load inertia to the [total inertia converted into motor shaft] is as follows:
The symbols in the formulas are:
J
S
: total inertia converted into motor shaft
J
M
: moment inertia of motor
R: reduction ratio of FHA actuator
L: Ratio of load inertia to motor inertia
N: variation ratio of load inertia
• Direct drive
Before: J
S
=J
M
(1+L) After: J
S’
=J
M
(1+NL) Ratio:
• FHA-C mini actuator drive
Before: After: Ratio:
In the case of the FHA-C mini actuator drive, as the reduction ratio is [R=30], [R=50], or [R=100] and the
square of the reduction ratio [R
2
=900], [R
2
=2500], or [R
2
=10000] the denominator and the numerator of
the ratio are almost [1]. Then the ratio is [Js’/Js 1]. This means that FHA drive systems are hardly
affected by the load inertia variation. Therefore, it is not necessary to take the load inertia variation in
consideration for selecting an FHA-C mini actuator or for setting up the HA-800 or HA-680 driver.
0.01
0.1
1
10
(kgf•cm•s
2
)
100 200
Nominal speed (r/min)
0
0.001
0.01
0.1
1
Inertia (kg•m
2
)
FHA-11C
-
100
FHA-14C
-
100
FHA-8C
-
100
FHA-8C
-
50
FHA-11C
-
50
FHA-14C
-
50
FHA-8C
-
30
FHA-11C
-
30
FHA-14C
-
30
J
S’
/J
S
=1+NL
1+L