Scanning probe for coordinate measurement using a translational parallel mechanism (prototyping of the isotropic mechanism and calibration of the mechanical parameters)

Abstract

A 3-dof active scanning probe using a translational parallel mechanism (TPM) is proposed. In this paper, the characteristics of the mechanism, optimum design, prototyping, and accuracy of the TPM are introduced. In the proposed optimum TPM design, the manipulability of the mechanism is equal in all directions. This implies that the positional sensitivities of the TPM share an isotropic relationship. The positional resolution of the mechanism becomes 0.58 μm in a cubic working range with side length of 1.6 mm. An experimental mechanism using the proposed design is introduced. Relationships between positioning errors and mechanical parameters of the TPM are revealed by applying the error propagation analysis. In order to evaluate the accuracy of the TPM, we have developed an experimental system for the measurement of the position of the TPM using image processing. By applying mechanical parameters calibration, the accuracy of the absolute position of the TPM has been improved to 3.4 μm. © 2012 The Japan Society of Mechanical Engineers.