Product manual

Model #RB3-065/035 22 R20140519
gripped object directly at a camera also affords the opportunity to
locate and orient the object within the grasp.
Estimating maximum accelerations:
Your model #RB3-065/035 VERSABALL® Gripper behaves slightly
differently for three different types of acceleration – vertical,
horizontal, and rotational. Begin by assessing the maximum vertical
acceleration, as this limit will be used to obtain estimates for the other
two accelerations as well. To estimate maximum vertical acceleration,
simply grip the object as it would be during use, and then conduct a
pull-out force test. Next, with knowledge of the vertical pull-out force
F and the mass of the object m, the maximum vertical acceleration can
be calculated as:
m
F
a
v
=
max,
The maximum rotational acceleration for a gripped object scales from
a
max,r
≈ a
max,v
in the worst case, up to much greater values in the best
case. The worst case for rotational acceleration is when the object has
a round shape along the axis of rotation, for example rotating a soup
can about its central axis, or rotating a sphere about any axis. From
there, maximum rotational acceleration improves as the object’s
number of sides decreases (e.g. from an infinite number of sides for a
circular object, to eight for an octagon, to three for a triangle, to
approximately two for a long narrow object). It is very difficult to
make a generalized prediction for maximum rotational acceleration in
the best case, but suffice to say it should exceed those achievable on
most robot arms.
Finally, to predict the maximum horizontal acceleration, consider
Figure 19. If the gripped object’s center of mass (CoM) is
approximately even with the bottommost edge of the gripper as
shown on the left, then a
max,h
≈ a
max,v
. If the CoM is embedded deeper
within the gripper, then maximum acceleration scales up to a much
higher level, again exceeding accelerations achievable on most robot
arms. If the CoM is located further than the gripper’s bottommost