Gang Liu, Wei Tang, Ying-Lin Ke, Qing-Liang Chen and Yunbo Bi
The purpose of this paper is to propose a new model for optimizing pre-joining processes quickly and accurately, guiding workers to standardized operations. For the automatic…
Abstract
Purpose
The purpose of this paper is to propose a new model for optimizing pre-joining processes quickly and accurately, guiding workers to standardized operations. For the automatic riveting in panel assemblies, the traditional approach of determination of pre-joining processes entirely rests on the experience of workers, which leads to the improper number, location and sequence of pre-joining, the low quality stability and the high repair rate in most cases.
Design/methodology/approach
The clearances computation with the complete finite element model for every process combination is time-consuming. Therefore a fast pre-joining processes optimization model (FPPOM) is proposed. This model treats both the measured initial clearances and the stiffness matrices of key points of panels as an input; considers the permissive clearances as an evaluation criterion; regards the optimal number, location and sequence as an objective; and takes the neighborhood-search-based adaptive genetic algorithm as a solution.
Findings
A comparison between the FPPOM and complete finite element model with clearances (CFEMC) was made in practice. Further, the results indicate that running the FPPOM is time-saving by >90 per cent compared with the CFEMC.
Practical implications
This paper provides practical insights into realizing the pre-joining processes optimization quickly.
Originality/value
This paper is the first to propose the FPPOM, which could simplify the processes, reduce the degrees of freedom of nodes and conduct the manufacturers to standardized manipulations.
Details
Keywords
Hua Liu, Weidong Zhu, Huiyue Dong and Yinglin Ke
To gain accurate support for large aircraft structures by ball joints in aircraft digital assembly, this paper aims to propose a novel approach based on visual servoing such that…
Abstract
Purpose
To gain accurate support for large aircraft structures by ball joints in aircraft digital assembly, this paper aims to propose a novel approach based on visual servoing such that the positioner’s ball-socket can automatically and adaptively approach the ball-head fixed on the aircraft structures.
Design/methodology/approach
Image moments of circular marker labeled on the ball-head are selected as visual features to control the three translational degrees of freedom (DOFs) of the positioner, where the composite Jacobian matrix is full rank. Kalman–Bucy filter is adopted for its online estimation, which makes the control scheme more flexible without system calibration. A combination of proportional control with sliding mode control is proposed to improve the system stability and compensate uncertainties of the system.
Findings
The ball-socket can accurately and smoothly reach its desired position in a finite time (50 s). Positional deviations between the spherical centers of ball-head and ball-socket in the X-Y plane can be controlled within 0.05 mm which meets the design requirement.
Practical implications
The proposed approach has been integrated into the pose alignment system. It has shown great potential to be widely applied in the leading support for large aircraft structures in aircraft digital assembly.
Originality/value
An adaptive approach for accurate support of large aircraft structures is proposed, which possesses characteristics of high precision, high efficiency and excellent stability.