The test planes and test paths of this standard are defined with respect to a cube located inside the workspace of the robot. Various diagonal planes of this cube are used to locate the test planes, paths and points. This standard specifies tests for the measurement of fourteen performance characteristics. The most commonly used characteristics are those of accuracy and repeatability.

From the figure above, the robot was commanded to move to the origin of the coordinate frame (rectangle), but instead attained all the positions marked by the triangles. The centroid of these positions, called the barycenter by this standard, is marked by the cross. The cloud of attained positions usually forms an ellipsoid. The lengths and orientations of the principal axes of this ellipsoid provide significant information about the performance of the robot at this position of its workspace. To average the results of this test over a significant portion of the workspace, both the US and ISO standards require that this test be performed at several locations on the test plane and that the data are mixed together.
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