Pose measurement approach based on two-stage binocular vision for docking large components

Abstract

Large components docking is an important step in industrial manufacturing. During the docking process, the relative pose of joining components needs real-time and accurate acquisition. Existing methods rely on expensive and complex optical instruments. Photogrammetry has the advantages of low cost and fast measurement speed, but its measurement accuracy decreases sharply along with the increase of the measurement range. This paper proposes a two-stage binocular vision which consists of two sets of binocular vision systems with different accuracy levels in the same coordinate system. Binocular system with corresponding structural parameters is designed for pose measurement at corresponding stages to solve the contradiction between the range and accuracy in measurement. A triangulation and spatial plane fitting method is proposed to calculate relative poses without introducing coordinate transformation errors. We adopt a novel 3D optimization method to further improve the accuracy. Experiment results show that this method can meet the measurement range and accuracy requirements for large components docking. Compared with traditional combined vision measurement station based on multi-vision sensor, the proposed method reduces coordinate transformation errors and overcomes the contradiction between the measurement range and accuracy, which can improve the accuracy and meet the requirements of engineering application.

Posture adjustment method of large aircraft components based on multiple numerical control positioners

“…The Jacobian matrix corresponding to the Z axes of the three NCPs is The rank of 3 z J is 3, and the 6 DOFs of the PAM terminal cannot be constrained, so the other three axes of the PAM need to be selected as the position control axes. When the X axes of three NCPs are selected as the position control axes, the Jacobian matrix of the PAM is The rank of 3,3 , zx J is less than or equal to 5, which cannot limit the 6 DOFs of the terminal.…”

“…The docking of LAC is one of the main tasks of aircraft assembly, and the docking accuracy is a crucial factor affecting the final quality of aircraft products [2]. The traditional docking of LAC relies on a large number of special toolings and manual operations, which is labour-intensive, inefficient and difficult to improve the assembly accuracy, and the design and manufacture of a large number of special toolings increase the cost and cycle of aircraft manufacturing [3]. With the rapid development of digital measurement technology [4], automatic control technology [5] and sensor technology [6], automatic docking system has been gradually adopted in the assembly of LAC [7] [8].…”

Trajectory planning method for docking of large aircraft components

“…The traditional docking mode of LAC has the disadvantages of high labor intensity, low assembly efficiency, poor universality of tooling and poor assembly quality. In addition, the contact force of the docking interface is also challenging to control, and interference and collision are easy to occur during the docking process (Chen et al , 2020).…”

An Improved Sum of Squared Difference Algorithm for Automated Distance Measurement

“…It needed to equip with TOF sensors, and the hardware design was complicated. In addition, in two sets of binocular vision systems with different accuracy levels, the method of triangulation analysis and spatial plane fitting were proposed to calculate relative poses [7]. This algorithm had a higher accuracy than other methods, but it required four cameras, which had a high cost.…”