Epson C8 Series, Manipulator Manual, Page: 63 / 346

Setup & Operation 4. End Effectors
C8 Rev.13 49
The moment M (Nm) and inertia moment I (kgm
2
) when the volume of the load (end effector
+ work piece) is small can be obtained by the following formula.
M (Nm) = m(kg) × L (m) × g (m/s
2 )
I (kgm
2
) = m(kg) × L
2
(m)
m : Weight of load (kg)
L : Eccentric quantity of load (m)
g : Gravitational acceleration (m/s
2
)
T
L
Joint Rotation Center
The figure below shows distribution of the center of gravity when the volume of the load
(end ef work piece) is small.
Design the end effector so that the center of gravity is within the allowable moment.
If the volume of the load is large, calculate the moment and inertia moment by referring to
Setup & Operation 4.3.2 INERTIA setting - Calculating the Inertia Moment .
Center of gravity of load from the Arm #5 rotation center [mm]
C
ent
er
of
gr
av
ity
of
load f
rom
the A
rm
#6
rot
at
ion
c
ent
er
[mm]
300
250
200
150
100
50
0
0 50 100 150 200 250 300
1 kg
2 kg
3 kg
4 kg
5 kg
6 kg
7 kg
8 kg
Max. Eccentric Quantity of Load
(Distance between the joint rotation center and the load’s center of gravity)
Joint 1 kg 2 kg 3 kg 4 kg 5 kg 6 kg 7 kg 8 kg
#4 300 mm 300 mm 300 mm 300 mm 300 mm 280 mm 242 mm 212 mm
#5 300 mm 300 mm 300 mm 300 mm 300 mm 280 mm 242 mm 212 mm
#6 300 mm 274 mm 224 mm 194 mm 173 mm 158 mm 137 mm 120 mm
When calculating the critical dimension of the load using the allowable moment and inertia
moment, the calculated value represents a distance from the Arm #5 rotation center, not the
distance from the flange. To calculate the distance from the flange to the load’s center of
gravity, subtract the distance from the center of the Arm #5 rotation center to the flange (=80
mm) as shown in the example below.