A contour-guided pose alignment method based on Gaussian mixture model for precision assembly. Issue 3 (17th June 2021)

• Record Type: Journal Article
• Authors: Guo, Pengyue; Zhang, Zhijing; Shi, Lingling; Liu, Yujun
• Is Part Of: Assembly automation. Volume 41:Issue 3(2021)
• Page Start: 401
• Page End: 411
• Publication Date: 2021-06-17
• Subjects: Pose measurement -- Gaussian mixture model -- Precision assembly -- Point set registration; Automation -- Periodicals; Automatic machinery -- Periodicals; Assembly-line methods -- Periodicals; Industrial engineering -- Periodicals; 670.42705
• DOI: 10.1108/AA-08-2020-0103
• Languages: English
• ISSNs: 0144-5154

Abstract

Abstract : Purpose: The purpose of this study was to solve the problem of pose measurement of various parts for a precision assembly system. Design/methodology/approach: A novel alignment method which can achieve high-precision pose measurement of microparts based on monocular microvision system was developed. To obtain the precise pose of parts, an area-based contour point set extraction algorithm and a point set registration algorithm were developed. First, the part positioning problem was transformed into a probability-based two-dimensional point set rigid registration problem. Then, a Gaussian mixture model was fitted to the template point set, and the contour point set is represented by hierarchical data. The maximum likelihood estimate and expectation-maximization algorithm were used to estimate the transformation parameters of the two point sets. Findings: The method has been validated for accelerometer assembly on a customized assembly platform through experiments. The results reveal that the proposed method can complete letter-pedestal assembly and the swing piece-basal part assembly with a minimum gap of 10 µm. In addition, the experiments reveal that the proposed method has better robustness to noise and disturbance. Originality/value: Owing to its good accuracy and robustness for the pose measurement of complex parts, this method can be easily deployed to assembly system.