Omron SCARA R6Y-XC Series, User Manual, Page: 58 / 203

3-20
CHAPTER 3 Installation
6 Attaching The End Effector
6-1 R-axis tolerable moment of inertia and acceleration coefficient
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. 3-10
to Fig. 3-61 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: R6YXCH250
Assume that the mass of the load installed to the R-axis is 1.5kg and the
moment of inertia around the R-axis is 0.02kgm
2
(0.2kgf·cm·sec
2
). When
the tip mass parameter is set to 2kg, the robot can be operated by reducing
the X, Y and R-axis acceleration coefficients to 60%, as can be seen from
Fig. 3-11.
Be sure to select an optimum tip mass and acceleration coefficient
parameters 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 “OMRON Robot Controller User’s Manual”.
3) For information on how to calculate the moment of inertia of the load, re-
fer to "6-2 Equation for moment of inertia calculation" in Chapter 3 of the
standard model X user's manual. Note that it is not easy to precisely calcu-
late the moment of inertia.
If a calculated value smaller than the actual moment of inertia is set, re-
sidual vibrations may occur. If this happens, reduce the acceleration
coefficient parameter even further.
CAUTION
THE ROBOT MUST BE OPERATED WITH CORRECT TOLERABLE
MOMENT OF INERTIA AND ACCELERATION COEFFICIENTS
ACCORDING TO THE MANIPULATOR TIP MASS AND MOMENT OF
INERTIA. 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.