Probe, motion guiding device, position sensing apparatus, and position

Abstract

A probe is mounted on a machine head which has mobility and readouts in three linear coordinate directions. The probe carries a stylus with a tip which has mobility relative to the head in three nonlinear coordinate directions which are nonaligned with the axes of head movement. A mathematical model, produced by a calibration technique before measurements are taken, translates readouts of the stylus tip's position in the nonlinear coordinates into values which are aligned with the coordinate axis system of the machine head. The probe has three flex wire motion guiding devices connected together in series, and each of these devices has a second member movably supported on a first member by flexible wires arranged in two nonparallel sets of parallel wires. The second member is thus constrained to movement in a single arcuate path which lies transverse to the longitudinal axes of the wires in both sets. The distance of movement between the first and second members is sensed by a differential optical transducer which has two light source elements which emit light beams and two light sensor elements which receive these beams. The elements on each of the relatively movable members face in opposite directions so that movement between the members lengthens one beam and shortens the other beam. An electronic circuit compares signals from the light sensor elements and provides an output signal which indicates the position of the second member relative to the first member.