Abstract: The accessibility of measuring points has to be analyzed before contact probing
with coordinate measuring machines (CMMs) to avoid collision and provide accessible
orientations for the determination of measurement orientations. This paper proposes a generic
accessibility analysis algorithm for common styluses. Users construct interactively the models of
styluses, probes and other CMMs components. Inaccessible orientations of measuring points are
excluded fast according to the kind of stylus tip. Then, the static and dynamic accessibility of
measuring points in each measurement orientation is analyzed through computing the minimum
distance between CMMs components and barriers such as workpiece and fixture. All accessible
orientations of measuring points are obtained accordingly. Because barriers are discretized for
accessibility analysis, this method is suitable for any complicated workpiece.

Key words: measuring points, accessibility, coordinate measuring machines, contact probing