The application of vision system in the detection of automobile door lock

1 Introduction

Car door locks have the characteristics of many models and specifications, large structural differences, many inspection items, and some structures are loose and easily deformed; car door lock assembly and inspection production lines require fast equipment inspection and low failure rates, and allow certain scalability of product inspection content .

In the past, most of the methods used were to decompose the detection items into each substation for separate detection. This often resulted in defects in the equipment structure of each substation, complicated operation, long equipment design cycle, high failure rate and other defects. The inspection needs to rely on manual visual inspection, which is not only labor-intensive, but also prone to errors due to manual factors.

With the development of industrial production, the manufacturing level of automation equipment is also increasing day by day. The introduction of machine vision (hereinafter referred to as vision) system has solved these problems well.

2 Introduction to Vision Technology

Vision technology is to use a machine to replace the human eye for measurement and judgment. It takes an image through a camera (Camer a) and converts pixel distribution, brightness, color and other information into digital signals; the image system operates on these signals to extract The characteristics of the image, and on this basis, it realizes multiple functions such as pattern recognition, coordinate calculation, and gray distribution map, so as to make logical judgments to control field devices.

Compared with manual inspection, machine vision inspection has the following advantages.

3 Design of vision system

3.1 Hardware design

(1) Image acquisition part: lens PULNix TM-200, Cognex image acquisition card (can connect 4 groups of lenses); (2) image processing part: PC (DELL GX5200); (3) electromechanical control part: SeaIO I / O Card (PCI slot), control cabinet (built-in air switch, wiring terminals, etc.) constitute the electrical control system; (4) Electromechanical executive parts: buttons, sensors, cylinders, valve terminals, indicator lights, buzzers, etc .; (5) Human-computer interaction: display, mouse, keyboard.

3.2 Software design

This project is based on Cognex's visual analysis tool and has developed a set of visual operation platform.

(1) Software environment for system development.

Windows 2000 or Windows XP or above operating system; Office 2000 or above; VisiONPro 50 or above; SeaIO_v030103 or above; VS2005TF.

(2) Requirements for software development.

Automobile door locks have many detection points (23 points in this example) and many varieties. This requires that the software can freely combine the detection points into various varieties, and the operation interface is as simple as possible and easy to operate.

(3) The function of the software.

Figure 1 main interface

The main interface of the software is shown in the figure. On the left is an overview of the current car lock model, the selected lens, the used positioning origin, and the detected point. On the right is rough information such as detection results and device status. The upper part of the middle part is the actual image detected by the system. Those that pass the test are surrounded by a green border, those that fail are surrounded by a red border, and are equipped with the text name of the detected point. The image will be displayed by default as an image that contains unqualified inspection points in the inspection results. There are four small display areas on the lower side of this image, corresponding to different cameras in the system. If the image contains unqualified points, the outside of the image will be circled with a red border. The bottom is the detailed information of each detection point. As shown in Figure 1.

In addition, there are "input display", "manual control" and "status alarm" property pages in the main window. Added "Model Selection", "Camera", "PMAlignFixture", "Tools", "Type", and "Visual Run" options in the menu "Project". as shown in picture 2.

Figure 2 Project submenu.