System Setup
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9.4.2.1 How to calculate tool load information
• Weight: W (unit: kg)
The total weight of the installed tool is set.
It is not necessary to set the correct value. However, it is recommended to set a value
that is somewhat higher than the actual load (round the value up between 0.5 and 1 kg
for small and medium-sized robots and between 1 and 5 kg for larger robots).
• Centre of gravity: xg, yg, zg (unit: mm)
The center of gravity of the installed tool is set here as the position in the flange
coordinates.
Since it is generally difficult to determine an exact center of gravity, an approximate
value can be set. Determine and set the center of gravity as an approximate value on
the basis of the tool's external contour.
Set the value if the center of gravity of the installed tool clearly results from the
specifications.
• Moment of inertia at the center of gravity: lx, ly, lz (unit: kgm²)
The tool's moment of inertia is at the center of gravity.
The value is calculated for each axis of the coordinates that is parallel to the flange
coordinates and whose home position is the tool's center of gravity.
It is not necessary to set the correct value. However, it is recommended to set a value
that is somewhat higher than the actual load.
The setting is used to calculate the moment of inertia for each robot axis. However, the
moment of inertia at the center of gravity does not normally have to be set, since this
value is low enough for the moment of inertia calculated from the weight and the center
of gravity.
This setting is required, however, if the tool's moment of inertia is large (as a rough
guide, a tool is large if it's size is more than twice the distance between the flange and
the center of rotation).
Rough value of the moment of inertia at the center of gravity can be calculated by the
following methods.
• Method for approximating the whole tool in a hexahedron or cylinder.
• Method of calculation from the weight and the center of gravity of multiple loads.
Further details are explained in the examples of settings below.
The size of the tool is not too big. Setting the moment of inertia at center of gravity is
not necessary.
The size of the tool is big. Setting the moment of inertia at center of gravity is neces-
sary.
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