Allowable kinetic energy for the rotary actuator is limited. The limit of rotation time is obtained by calculating
the moment of inertia.
Please refer below to calculate the moment of inertia.
Basic moment of inertia
2
r
m
I
m
: Weight
[ kg ]
r : Center of gravity of load and distance of rotational axis [ m ]
This shows moment of inertia of
“m (weight)” at “r” distance from the axis of rotation.
The calculation for the moment of inertia depends on the shape of the object.
Date 2 shows formulae to find moment of inertia of various shapes.
Model selection
Select a model by applying the calculated moment of inertia to the graph 2 below.
Graph 2. Moment of inertia
– Rotation time
1.
〈
How to read graph
〉
When
・
Moment of inertia
…
20 x 10
-6
・
Rotation time
…
0.14s/90
°
,
MSUA 3 or MSUA 7, 20 will be selected.
2.
〈
Calculation example
〉
Shape of load: Column with a radius of
0.05m and weight of 0.12kg
Rotation time: 0.2s/90
°
2
6
2
10
150
2
05
.
0
12
.
0
m
kg
I
Based on the graph of moment of inertia
and rotation time, find the intersection
by extending a vertical axis (moment of
inertia) 150 x 10
-6
kg
・
m
2
and horizontal
axis (rotation time) 0.2s/90
°
.
MSUA 7 or MSUA 20 is selected
Because the intersection is within the
Selecting range of MSUA 7.
- 25 -
Fig. 1 Moment of inertia
2020-10-13 11:15
DI987004
