Geometric Robot Calibration Using a Calibration Plate

TL;DR

This paper presents a new, cost-effective geometric robot calibration method using a calibration plate with known distances, offering a robust alternative to traditional measurement systems, demonstrated on a gantry robot.

Contribution

The paper introduces a novel calibration approach using a calibration plate and mathematical error modeling, which is simpler and more portable than conventional methods.

Findings

Calibration plate method yields accurate error parameter identification.

Results are comparable to laser tracker calibration.

Method is applicable to various robot types.

Abstract

In this paper a new method for geometric robot calibration is introduced, which uses a calibration plate with precisely known distances between its measuring points. The relative measurement between two points on the calibration plate is used to determine predefined error parameters of the system. In comparison to conventional measurement methods, like laser tracker or motion capture systems, the calibration plate provides a more mechanically robust and cheaper alternative, which is furthermore easier to transport due to its small size. The calibration method, the plate design, the mathematical description of the error system as well as the identification of the parameters are described in detail. For identifying the error parameters, the least squares method and a constrained optimization problem are used. The functionality of this method was demonstrated in experiments that led to promising results, correlated with one of a laser tracker calibration. The modeling and identification of the error parameters is done for a gantry machine, but is not restricted to that type of robot.