Motoman PX2750, Manual

Page: 403 / 611

3.11 ARM Control
3-58
<Example 2>
It is necessary to set the moment of inertia at the center of gravity when the entire size of the
tool and workpiece is large enough comparing with the distance from the flange to the center
of gravity position.
Calculate the moment of inertia at the center of gravity roughly from the expression (Refer to
the above-mentioned supplement: "The own moment of inertia calculation for hexahedron and
cylinder"), by approximating the entire tool in the shape of the hexahedron or the cylinder.
If the weight of held workpiece is greatly different like in the handling usage etc, it is more
effective to set tool load information on each workpiece and to switch the tool on each step
according to the held workpiece. Set the tool load information in the state to hold the heaviest
workpiece when the tool is not switched.
Weight: W = 55 + 40 = 95
= approx. 100[kg]
Center of gravity: Position at flange right under 250mm almost
(Xg, Yg, Zg) = (0,0,250)
Moment of inertia at the center of gravity:
The hexahedron of 0.500 x 0.400 x 1.000[m] which encloses the entire
hand + workpiece is assumed.
By the
expression to calculate the
own moment of inertia of hexahedron,
Ix = ( Ly
2
* Lz
2
/ 12) *
= ( (0.400
2
+ 1.000
2
) / 12) * 100 = 9.667 = approx. 10.000
Iy = ( Lx
2
* Lz
2
/ 12) * W = ( (0.500
2
+ 0.400
2
) / 12) * 100 = 3.417 = approx. 3.500
Iz = ( Lx
2
* Ly
2
/ 12) * W = ( (0.500
2
+ 1.000
2
) / 12) * 100 = 10.417
<Setting>
• W : 100.000 kg
• Xg : 0.000 mm
• Yg : 0.000 mm
• Zg : 250.000 mm
• Ix : 10.000 kg.m
2
• Iy : 3.500 kg.m
2
• Iz : 10.500 kg.m
2
Weight of Hand :
Approx. 55kg
Weight of Workpiece :
Approx. 40kg
250
1000
400
500
X F
Z F
Y F