Patent ID: 6952882

Claim:
A portable coordinate measurement machine (CMM) for measuring the position of an object in a selected volume, comprising: a manually positionable articulated arm having opposed first and second ends, said arm including a plurality of joints; a measurement probe attached to a first end of said articulated arm; an electronic circuit which receives the position signals from transducers in said arm and provides a digital coordinate corresponding to the position of the probe in a selected volume; and wherein at least one of said joints further comprise; a periodic pattern of a measurable characteristic; at least one read head spaced from and in communication with said pattern; said pattern and said read head being positioned within said joint so as to be rotatable with respect to each other; and at least one sensor which measures relative movement in said articulated arm with respect to said at least one read head so as to improve the measurement accuracy of said at least one read head.