Articulated Arm Coordinate Measuring Machine Calibration by Laser Tracker Multilateration

Abstract

A new procedure for the calibration of an articulated arm coordinate measuring machine (AACMM) is presented in this paper. First, a self-calibration algorithm of four laser trackers (LTs) is developed. The spatial localization of a retroreflector target, placed in different positions within the workspace, is determined by means of a geometric multilateration system constructed from the four LTs. Next, a nonlinear optimization algorithm for the identification procedure of the AACMM is explained. An objective function based on Euclidean distances and standard deviations is developed. This function is obtained from the captured nominal data (given by the LTs used as a gauge instrument) and the data obtained by the AACMM and compares the measured and calculated coordinates of the target to obtain the identified model parameters that minimize this difference. Finally, results show that the procedure presented, using the measurements of the LTs as a gauge instrument, is very effective by improving the AACMM precision.

Measurement technologies for precision positioning

“…The multilateration method was initially proposed for high-accuracy surface form metrology [81]. Recently, it is widely used for calibrating CMMs and machine tools [183]. A laser-based multilateration system is typically composed of three laser-based measuring stations and a wide-angle retroreflecting target.…”

Verification of an articulated arm coordinate measuring machine using a laser tracker as reference equipment and an indexed metrology platform

“…Furthermore, it is proved with these tests that the real accuracy of the laser tracker obtained in the experimental procedure, ±0.005 mm, is better than the one specified by the manufacturer in the product specification for the model Leica LTD600D, ±10 lm ± 0.5 lm/m, corresponding to an accuracy of ±10.6 lm for a 1.2 m length. A proposal for fixing the lack of accuracy of laser trackers that is required for AACMM's calibration is the use of multiple laser trackers through multilateration [34,10]. This technique enables a decrease in the measurement uncertainty by means of angular noise reduction.…”

“…Kovac and Frank [6] developed a new high precision measuring device for AACMM testing and calibration based on laser interferometer measurements along a line gauge beam. Santolaria et al [5,[7][8][9][10] reported a method to calibrate an AACMM based on the Denavit-Hartenberg kinematic model parameters [11]. These parameters are optimized measuring a calibrated ball bar gauge located at different orientations and positions of the AACMM working volume.…”

A Novel Kinematic Parameters Identification Method for Articulated Arm Coordinate Measuring Machines Using Repeatability and Scaling Factor

“…Due to its flexibility and portability, there is a growing demand for applications at industrial sites [3]. However, as a multi-joint serial structure like robotic arm [4,5] AACMMs have lower accuracy comparing with the normal coordinate measuring machines.…”