Portable coordinate measurement machine having a bearing assembly with an optical encoder

摘要

A portable articulated arm coordinate measurement machine having an articulated arm that includes a first arm connected to a second arm segment by a connecting segment. An assembly is provided having a first pair of bearings and a first optical encoder and a second pair of bearings and a second optical encoder The first optical encoder includes a first patterned disk and a first read head. The second optical encoder includes a second patterned disk and a second read head. The first and second patterned disks are both fixed with respect to the connecting segment. An electronic circuit is operably coupled to the first read head and the second read head, the electronics being configured to determine three-dimensional coordinates of the probe based at least in part on a first angle and a second angle measured by the first and second optical encoders.

主权项

1. A portable articulated arm coordinate measurement machine, comprising:
a manually positionable articulated arm having opposed first and second ends, the articulated arm including a plurality of connected arm segments, the plurality of arm segments including a first arm segment connected to a second arm segment by a connecting segment; a base section connected to the second end; a probe connected to the first end; electronics; a first patterned disk having a first periodic pattern of a measurable characteristic and a first read head in proximity to the first patterned disk; a second patterned disk having a second periodic pattern of the measurable characteristic and a second read head in proximity to the second patterned disk; a first pair of bearings including a first bearing and a second bearing which rotate about a first axis; and a second pair of bearings including a third bearing and a fourth bearing which rotate about a second axis; wherein the first arm segment rotates about the first axis, the second arm segment rotates about the second axis, and the connecting segment is fixed with respect to the first axis and the second axis; wherein one of the first patterned disk and the first read head is fixed with respect to the connecting segment, and the other of the first patterned disk and the first read head is fixed with respect to the first arm segment, the first read head producing a first signal, the first signal indicating a first angle of rotation of the first arm segment about the first axis; wherein one of the second patterned disk and the second read head is fixed with respect to the connecting segment, and the other of the second patterned disk and the second read head is fixed with respect to the second arm segment, the second read head producing a second signal, the second signal indicating a second angle of rotation of the second arm segment about the second axis; wherein the electronics is operably coupled to the first read head and the second read head, the electronics being configured to determine three-dimensional coordinates of the probe based at least in part on the first angle and the second angle; and wherein the first arm segment and one of the first patterned disk and the first read head are supported for rotation about the first axis by bearings selected from the group consisting of the first bearing and the second bearing.