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3-17
CHAPTER 3 Installation
7 Attaching The End Effector
7-1 R-axis tolerable moment of inertia and acceleration coeffi-
cient
1) The moment of inertia of a load (end effector and workpiece) that can be
attached to the R-axis is limited by the strength of the robot drive unit and
residual vibration during positioning. It is therefore necessary to reduce the
acceleration coefficient in accordance with the moment of inertia.
2) The R-axis tolerable moment of inertia and the acceleration coefficient ver-
sus R-axis moment of inertia for each robot model are shown in Fig. 3-9,
Fig. 3-10 and Fig. 3-11 on the subsequent pages. The symbols A
X
, A
Y
, and A
R
in each figure respectively indicate the acceleration coefficients of the X-
axis, Y-axis and R-axis. The symbol I
R
(J
R
) is the moment of inertia of the
load around the R-axis and m is the tip mass.
Example: YK120X
Assume that the mass of the load installed to the R-axis is 0.15kg and the
moment of inertia around the R-axis is 0.0005kgm
2
(0.005kgfcmsec
2
). When
the tip mass parameter is set to 0.2kg, the robot can be operated by reducing
the X, Y and R-axis acceleration coefficients to 50%, as can be seen from
Fig. 3-9.
Be sure to select an optimum tip mass and acceleration coefficient param-
eters that meet the mass of the load and moment of inertia before using the
robot.
To make settings for the tip mass and acceleration coefficient, refer to the
separate "YAMAHA robot controller owner's manual".
3) Methods for calculating the moment of inertia of the load are shown in Sec-
tion 6-2, however, it is not easy to precisely figure out these values.
If a calculated value smaller than the actual moment of inertia is set, residual
vibrations may occur. If this happens, reduce the acceleration coefficient pa-
rameter even further.
!
CAUTION
The robot must be operated with correct tolerable moment of inertia and accel-
eration coefficients according to the manipulator tip mass and moment of iner-
tia. If this is not observed, premature end to the life of the drive units, damage to
the robot parts or residual vibration during positioning may result.