Journal of the Japan Cociety for Precision Engineerig, Vol.66, No. 11 (2000) 1711-1715.

Coordinate Measuring Machine using Parallel Mechanism (4th Report)
-Development of Trial Measuring Machine-

Takaaki OIWA and Shuhei BABA

Abstract

This study has proposed a new coordinate measuring machine (CMM) based on a spatial in-parallel kinematics consisting of closed loop link mechanism. In this report, the construction and the simple calibration have been described for developed CMM. The CMM employs specially made spherical joints and revolutionary joints, precise linear scales built in three prismatic joints, a touch trigger probe and an octahedral truss frame. Variations in the length of the prismatic joints driven by AC servo motors move the probe in three-dimensional space. When the probe touches the measuring object, the probe coordinates are calculated from the scale values. Moreover, the simple calibration of the CMM has been performed by measuring the block gauges in XYZ directions. The kinematic parameters on the location of the spherical joints and the initial length of the struts have been adjusted gradually by repetitive operation so that the lengths of the gauge are correctly calculated. The results of test measurement show that the standard deviation of measured data, or the measuring repeatability is less than 0.21 Ám. Measured deflections, moreover, are less than 10 Ám when measuring the gauge blocks with maximum length of 50mm.

Key words

coordinate measuring machine, parallel mechanism, calibration, kinematic parameter