A high accuracy six-dimensional motion measuring device: Design and accuracy evaluation
Journal
Mechanism and Machine Theory
Journal Volume
191
Date Issued
2024-01-01
Author(s)
Lei, Wei Tai
Abstract
A novel six-dimensional Motion Measuring Device (MMD) is designed and evaluated in this study. The MMD is based on the Stewart–Gough platform (SGP) mechanism, but the struts with U-joints are replaced by measuring ball bars, each with two precision ball joints. The independent kinematic parameters of the MMD are simplified thereby to twelve ball joint positions and six center distances of the ball bars, 42 parameters in total. An error budget analysis of the kinematic parameters using the Monte Carlo simulation is performed to find the tolerances of the kinematic parameters for micrometer-level measuring accuracy. To ensure accurate measurement on the shop floor without temperature control, the MMD is augmented with a novel referencing module, including a reference plate and a reference ball bar. The reference plate is used to establish the center distance function (CDF) of each measuring ball bar, which eliminates the geometric and initial thermal error thereof. The reference ball bar is used to compensate for thermal errors of the ball bars induced by the change of ambient temperature. Experimental evaluations prove the effectiveness of the novel referencing module and the micrometer-level measuring accuracy of the MMD.
Subjects
Double ball bar | Six-dimensional measurement | Stewart–Gough platform (SGP) | Thermal error compensation
Type
journal article