COORDINATE MEASURING MACHINE HAVING ARTICULATED ARM

摘要

A coordinate measuring machine includes a support structure (12), an articulated arm (14) having a first end pivotally connected to the support structure (12) and a second end that is movable in a horizontal plane. A Z-ram assembly (16) is mounted to the second end of the articulated arm (14). The Z-ram assembly (16) includes a Z-ram housing (31) and a probe (28) that is vertically movable with respect to the Z-ram housing (31). The probe (28) is movable within a measurement volume defined by the articulated arm (14) and the Z-ram assembly (16). The coordinate measuring machine further includes a measuring assembly for determining coordinates of the probe (28) in the measurement volume. The articulated arm (14) preferably includes first and second arm assemblies (20, 22) that have a parallelogram configuration to prevent substantial rotation of the Z-ram assembly (16) as the articulated arm (14) is moved in the horizontal plane. The angles of the arm (14) are preferably measured using a sensor which includes a pattern of parallel, straight grating lines.