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Chen H.,Hebei University of Technology | Chen H.,Hebei Control Engineering Technology Research Center | Sun H.,Hebei University of Technology | Sun H.,Hebei Control Engineering Technology Research Center | Xu D.,CAS Institute of Automation
Hanjie Xuebao/Transactions of the China Welding Institution | Year: 2012

A novel feature extraction and image processing method for narrow gap weld seam is proposed, which can effectively overcome all type of disturbance and reliably extract the seam feature points. First, a microscopic vision system with the line structure light is designed that can detect the seam image. Then, a method based on pixel point statistics and adaptive morphological contraction is proposed to segment the structured light stripe. After that a straight line and curve fit scheme are used to accurately gain the centre line of stripe. Finally, based on the distance search the characristic points of the seam is obtained by using the algorithm proposed in this research. The effectiveness of these methods is verified by some interesting results.


Chen H.,Hebei University of Technology | Chen H.,Hebei Control Engineering Technology Research Center | Fang Z.,CAS Institute of Automation | Xu D.,CAS Institute of Automation | And 2 more authors.
Jiqiren/Robot | Year: 2013

For the thin steel plate butt welding of containers, a visual control method of welding robot is proposed to recognize starting position and drive the weld torch to accurately track the starting position. Firstly, an iterative circle Hough transformation is presented, which can automatically obtain the region of interest including the torch characteristic point. In the second iteration, the torch characteristic point is recognized and extracted, robustly and quickly. Then the seam is recognized and its characteristic point is extracted by using line Hough transformation. Furthermore, an image space based visual control scheme of starting position is designed, and the accurate starting position control is achieved. The experimental results show that the proposed scheme can extract the torch's and seam's characteristic point coordinates, accurately and robustly. Moreover, the torch can be driven to the starting position quickly and accurately by using the visual control. Finally, test results in the container factory also verify the effectiveness of these methods, and the satisfactory results are obtained.


Chen H.-Y.,Hebei University of Technology | Chen H.-Y.,Hebei Control Engineering Technology Research Center | Sun H.-X.,Hebei University of Technology | Sun H.-X.,Hebei Control Engineering Technology Research Center | Wang H.,University of Manchester
Kongzhi yu Juece/Control and Decision | Year: 2011

A probability density function(PDF) optimal control strategy for a class of bounded affine nonlinear dynamic stochastic system is presented to drive the PDF of systems output to follow a desired PDF. An affine nonlinear state space model and PDF approximation equation can be obtained by using the linear B-spline approximation, which transfer PDF tracking to output tracking about nonlinear state model. Then a linear time-varying sequence approximation is employed to transfer the nonlinear systems to linear time-varying systems, and the optimal tracking controller of nonlinear dynamic stochastic system is obtained by using linear time-varying system iteration method. Theoretical analysis and simulation results show the effectiveness of the control algorithm.


Wang L.,Hebei University of Technology | Chen H.,Hebei Control Engineering Technology Research Center | Sun H.,Hebei Control Engineering Technology Research Center | Xing G.,Hebei Control Engineering Technology Research Center
Proceedings of the World Congress on Intelligent Control and Automation (WCICA) | Year: 2012

The laser weld is becoming more and more popular in the steel industrial production. However, the varying illumination, reflection and splatter lead to the irregular seam shape, which deteriorates the seam quality. In order to evaluate the seam shape and its quality, a 3D reconstruction method about micro and thin laser seam is proposed. The line structured light stripe is projected on the laser seam to be measured by a projector, and deformation of the stripe is captured by a CCD camera with industrial microscope lens. An image processing method that can efficiently locate the deformation of the stripe in the image plane is presented. Also, a novel procedure to automatically define the region of interest in the image is proposed. And then a straight line and curve fit is used to reduce the harm of the various disturbances and accurately gain the centre line of stripe. Furthermore, the characteristic points of the seam are obtained by using the distance search method. Finally, the proposed reconstruction method is applied to laser seam specimen, the desired performances are gained, and the results are satisfying. © 2012 IEEE.

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