METHOD FOR RESEARCHING DYNAMIC CHARACTERISTICS OF COORDINATE MEASURING MACHINES

Abstract

The article proposes a method for researching the dynamic characteristics of coordinate measuring machines (CMMs) by analyzing frequency characteristics and mathematical modeling. The developed methodology integrates analytical and numerical approaches to determine dynamic parameters, considering the mechanical structure. The method predicts CMM behavior under various conditions, improving accuracy for complex-profile parts and reducing dynamic errors.
The problem arises from the need to increase measurement speed without compromising accuracy. As the speed of the measuring head increases, dynamic errors grow, especially when measuring complex-profile surfaces. Existing methods often treat the CMM as a static system, neglecting inertia and vibrations. Therefore, a method that examines CMM dynamics is scientifically and practically significant.
The proposed method models the measuring system as masses, elastic elements, and dampers, described by differential equations. Frequency characteristics are calculated using Laplace transformation and the transfer function. A finite element model determines the amplitude-frequency (AFR) and phase-frequency characteristics (PFR) of the system. A second-order model describes the dynamic behavior of the CMM sensor head, considering gain coefficients and time constants.
The research evaluates control input influence using an integral quality indicator. The method combines analytical and numerical approaches, including frequency characteristics based on physical parameters and transfer functions for each direction. Numerical simulations confirm the method's effectiveness in reducing dynamic errors through compensation, decreasing errors by 2–3 times at speeds up to 50 mm/s when scanning complex-profile surfaces.
The study's results can be applied to improve CMM software and develop new control algorithms, enhancing measurement accuracy while maintaining productivity.