Geometric Robot Calibration Using a Calibration Plate

2025-10-29

AI Summary

Conventional geometric calibration of robots relies on expensive, bulky equipment—such as laser trackers—limiting practical deployment in industrial settings. Method: This paper proposes a low-cost, high-robustness calibration method based on a custom-designed calibration plate. By embedding measurement points with known geometric relationships on the plate, a system error model is constructed; key kinematic parameters are then identified via least-squares estimation integrated with constrained optimization. Contribution/Results: The core innovation lies in a miniaturized, mechanically stable calibration plate design that significantly reduces hardware cost and on-site installation complexity. Experimental validation on gantry-type robotic machine tools demonstrates calibration accuracy comparable to that of laser trackers—achieving positional errors below 0.1 mm—while exhibiting strong cross-platform adaptability. This work establishes a practical, rapid, and precise geometric calibration paradigm suitable for industrial environments.

Technology Category

• Intelligent Robots: State Estimation
• Machine Learning: Calibration & Uncertainty Quantification
• Computer Vision: Motion & Tracking

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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.

Problem

• Proposes a new geometric robot calibration method using calibration plates
• Determines robot error parameters through relative plate measurements
• Provides cheaper and more robust alternative to laser-based calibration

Innovation

• Uses calibration plate with known distances
• Employs least squares and constrained optimization
• Provides robust cheaper alternative to laser trackers