Probe parameters calibration for articulated arm coordinate measuring machine

Articulated Arm Coordinate Measuring Machine (AACMM) is a kind of portable coordinate measuring equipment with a flexible structure, which employs a series of rotating components around generally perpendicular axes. As a portable device, the probe parameters of AACMM will change after probe switching or dismounting and reassembling the same probe during shipping AACMM from one place to another to carry out measurement tasks. As incorrect coordinates will be given without the correct probe parameters, the probe parameters must be re-identified. By analyzing the identifiability of geometrical parameters of kinematical model and presenting the non-redundant-parameter model in this paper, a simple approach for the probe parameters calibration of AACMM is proposed, to improve its portability and ensure the accuracy of AACMM. In addition a very simple accessory was designed to hold the spherical probe as a data capture device. Gauss-Newton method was adopted as an optimization method to figure out the probe parameters. A program was developed to carry out the calibration process. Experimental results prove that the calibration approach proposed in the paper was effective.