Patent ID: 8825427
Filing Date: 2014-09-02
Classification: G01B

Abstract:
1. A method for calibrating a coordinate measuring machine having a sensor head and an evaluation and control unit that controls movements of the sensor head, the method comprising the steps of: providing a reference measurement object having known properties in a measuring volume of the coordinate measuring machine, recording a plurality of reference measured values on a plurality of measurement points on the reference measurement object using the coordinate measuring machine, determining calibration data using the reference measured values and using the known properties, and storing said calibration data in a memory of said evaluation and control unit in order to enable the evaluation and control unit to computationally correct for nonlinear measuring errors of the coordinate measuring machine, wherein the step of determining calibration data is carried out using the evaluation and control unit and comprises the steps of: defining a polynomial transformation having a plurality of polynomial coefficients, determining a first number of said polynomial coefficients as a function of the reference measured values and as a function of the known properties, forming a plurality of pairs of said polynomial coefficients, eliminating statistically dependent polynomial coefficients by eliminating one of the polynomial coefficients of each pair when a statistical correlation between the polynomial coefficients of said pair is determined to exceed a defined threshold value, thereby reducing the first number of said polynomial coefficients to a reduced second number, and iteratively repeating said step of eliminating such that statistical dependences among the polynomial coefficients of the reduced second number are reduced.