CN101852589A - Device and method for assembly and measurement of tiny parts in narrow space based on industrial endoscope - Google Patents

Abstract

The invention discloses an assembly measuring device and method for tiny parts in a narrow space based on an industrial endoscope, which is used for on-line measurement of the assembly of tiny parts in a narrow space. The assembly measurement device of the present invention is composed of an endoscope detection device, a precision linear motion platform and a computer. The endoscope inspection device collects the assembled image information and transmits it to the computer. The precision linear motion platform is used to move the endoscope inspection device, and the motion information of the precision linear guide rail is controlled by computer programming. In this measurement method, after the endoscope is measured at two different positions in the measurement direction, the computer combines the image information and motion position information of the two measurements before and after to process and calculate, so as to realize the measurement of the assembly information of tiny parts. The invention adopts the industrial endoscope and its light source interface to realize the integrated lighting observation in a narrow space. The precision motion guide rail with grating ruler is used to drive the movement of the endoscope, and the information of the movement track of the endoscope can be obtained in real time and accurately.

Description

Device and method for assembly and measurement of tiny parts in narrow space based on industrial endoscope

technical field

The invention relates to a device and method for assembling and measuring tiny parts in a narrow space based on an industrial endoscope, which belongs to the technical field of micro assembling and is used for on-line measurement of assembling tiny parts in a narrow space.

Background technique

Micro-assembly is a technology that assembles multiple micro-parts into complex micro-systems through accurate manipulation and positioning. At present, most micro-assembly work is still done manually by operators. Building an automated micro-assembly system will improve assembly accuracy, assembly efficiency and product stability, and at the same time free operators from boring and tedious micro-work, reducing the influence of human factors.

A key step in automated assembly is to check out assembly information in real time, quickly and accurately. Usually machine vision methods are used. In the detection of thin parts, the SP214202K30 line scan industrial camera of Canadian DALSA company and Nikon lens are used to obtain the scanned image of the parts to be inspected, and then through image preprocessing, contour vectorization and contrast detection, the MS 6x of Austrian RSF Elektronik company .x5 GA type grating scale is used together to obtain the part size parameters [Wu Jigang, Bin Hongzan, Optical Precision Engineering, 2007 (1) 124-130]. In order to achieve precise measurement and reduce image distortion, object-space telecentric lenses are usually used to replace conventional lenses in machine vision. It has been reported in the literature that telecentric lenses, CCD cameras and line source lasers can be used to achieve visual measurement of the gap width of welded joints. The weld joint gap detection algorithm based on gray projection integration can detect the boundary of the weld joint and the joint gap width. For a butt joint of 0.05 mm, the measurement accuracy of the joint gap width is better than 0.015 mm [Wu Jiayong, Wang Pingjiang, Chen Jihong, Chen Zhiyi , Journal of Welding Society, 2009(8), 105-108].

The above-mentioned device and method can realize rapid acquisition of assembled objects and assembly information in a conventional working environment. However, for micro-assembly operations in a small space, due to the small space, conventional industrial cameras cannot penetrate into it, and the lighting of the object under test is insufficient, so that it is necessary to find another way to obtain the image. At present, for the assembly of such products at home and abroad, industrial endoscopes are mostly used to realize online observation, which can be used for aircraft engines (including intake fans, turbine blades of compressors, combustion cylinders, gearboxes and lubricating oil tanks, etc.), various parts of the aircraft body (including fuselage, wings, landing gear system, vertical/horizontal tail, etc.), and other parts that cannot be directly observed by visual inspection. The inspection items are mainly affected by foreign object damage, corrosion, vulcanization, wear, cracks and pollutants [Liu Xiujuan, Hu Tieyu, Ren Yan, Engineering and Testing, 2009(1), 34-36]. In the inspection of the center hole of the steam turbine generator rotor in a thermal power plant, it is necessary to detect the possibility of surface fatigue cracks on the inner wall due to stress concentration. Straight rod side-view endoscope (produced by Tianjin Optical Instrument Factory) and endoscope (Wei Lin VIDEO2000) has realized this detection [Guo Xue, He Peipai, Huadian Technology, 2008 (4), 69-72], but the application of industrial endoscopes is still in the aspect of extending the vision of the human eye. Look but can't make precise measurements.

To sum up, the existing visual inspection methods cannot realize the rapid and accurate acquisition of tiny parts and their assembly process information in a narrow space.

Contents of the invention

The technical problem to be solved by the present invention is to provide a device and method for assembling and measuring tiny parts in a narrow space based on an industrial endoscope.

Technical scheme of the present invention is as follows:

The assembly measurement device based on industrial endoscope is composed of endoscope inspection device, precision linear motion platform and computer.

The endoscope detection device is composed of industrial endoscope, light source, digital camera or digital video camera and lens. There is a light source interface at the back end of the industrial endoscope, which can be connected to the light source and guide the light from the lens in the endoscope to the observation port of the endoscope to realize lighting in a narrow space. The endoscope is connected to a digital camera or digital video camera, and the collected image information is transmitted to the computer through the lens, and the computer processes the image online to obtain the position information of the tiny parts in the image coordinate system (camera field of view). Light sources such as halogen lamps, metal arc lamps and LEDs can be used as light sources.

The precision linear motion platform is composed of a precision linear guide rail and a grating ruler that move horizontally and vertically, and is used to move the endoscope inspection device. The control accuracy, the motion information of the precision linear guide is controlled by computer programming. The motion information of the precision linear guide and the image information of the endoscope are superimposed to realize the measurement of the assembly information of tiny parts.

式中前后两次测量中被测微小零件的像相对于相机视场中心的位置I₀、I₁，由对数码相机采集到的微小零件图像信息进行图像处理获得，前后两次测量内窥镜的位置差ΔX可由光栅尺精确测得。After the endoscope is measured at two different positions in the measurement direction, the computer combines the image information of the two measurements before and after and the position information of the guide rail to obtain the actual assembly position information of the measured tiny parts. According to the principle of optical imaging: (I ₀ and I ₁ are respectively the distance between the image of the tiny part to be measured and the center of the field of view of the camera in the two measurements before and after; X is the actual position of the tiny part to be tested; ΔX is the position difference of the endoscope between the two measurements before and after; F is the focal length; U is the object distance; K is the magnification from the digital camera to the monitor image), so the calculation formula for the actual position of the tiny parts is:

In the formula, the positions I ₀ and I ₁ of the images of the measured tiny parts relative to the center of the camera field of view in the two measurements before and after are obtained by image processing of the image information of the tiny parts collected by the digital camera. The position difference ΔX can be accurately measured by the grating ruler.

The effect and benefit of the present invention is that the industrial endoscope and its light source interface are used to realize the integrated lighting observation in a narrow space, the structure is simple, and the visual obstruction caused by too many devices extending into the narrow space is avoided, and the lighting device is also avoided. When it is different from the image acquisition device, it is difficult to acquire images at the best lighting point in a small space, thus affecting the image clarity. The precision motion guide rail with grating scale is used to drive the movement of the endoscope, which can obtain real-time and accurate information about the movement track of the endoscope, and then obtain the assembly information, avoiding the disadvantage that the measurement of assembly parameters cannot be realized when the endoscope is used alone, and expands the scope of development. Uses of endoscopes.

Description of drawings

Fig. 1 is a schematic diagram of the composition of the industrial endoscope assembly measurement system of the present invention.

Fig. 2 is a schematic diagram of the measurement method of the present invention.

Fig. 3 is a measurement schematic diagram of the present invention.

In the figure: 1 endoscope detection device; 2 precision linear motion platform; 3 industrial computer; 4 industrial endoscope; 5 the image of the tiny part tested in the first measurement; Like; 7 tiny parts to be tested;

A industrial endoscope; B lens; C digital camera or digital video camera; D light source; E stacked mold; F thin circular film to be tested;

A1 light source interface; A2 endoscope observation port; E1 cylindrical stacking hole; E2 process hole;

a precision linear guide for horizontal movement; b precision linear guide for vertical movement; c grating ruler;

O and O' are the optical center of the camera objective lens measured twice before and after;

Detailed ways

The specific embodiments of the patent of the present invention are described in detail below in conjunction with technical solutions and accompanying drawings.

The industrial endoscope assembly measurement system consists of an endoscope inspection device 1 , a precision linear motion platform 2 and a computer 3 . It is used to detect the stacking information of thin circular discs F with a diameter of 6.2mm. The thin ring sheet F is stacked in the cylinder stacking hole E1 in the stacking mold E. In order to realize the observation, an original process hole E2 with an inner diameter of 6 mm on the stacked mold is used to extend into the endoscope, and a 0.6 mm slit is opened between the process hole and the stacked hole for endoscopic image acquisition.

式中前后两次测量(即第一次测量和第二次测量，附图2中的5和6)微小零件的像相对于相机视场中心的位置I₀、I₁由对数码相机C采集到的图像信息进行图像处理获得，前后两次测量内窥镜的位置差ΔX可由光栅尺精确测得，由此获得每一个圆环片的实际位置信息并计算出圆环片间的相对位置。The endoscope inspection device consists of industrial endoscope A, lens B, digital camera C and light source D. The precision linear motion platform is composed of precision linear guide rails a, b and grating scale c that move horizontally and vertically. There is a light source interface A1 at the back end of the industrial endoscope A, which connects the LED point light source and guides the light from the lens in the endoscope to the observation port A2 of the endoscope to realize lighting in a narrow space. The camera interface at the end of the endoscope connects the lens B and the digital camera C, and transmits the assembled image information of the tiny parts collected to the computer 3, and then the computer processes the images online to obtain the position of the tiny parts in the image coordinate system (camera field of view). location information. The position movement of the endoscope is realized by the precision linear guide rail a moving in the horizontal direction and the precision linear guide rail b moving vertically with the addition of a grating ruler c. The motion information on the surface can be measured by the grating ruler c and transmitted to the computer 3 . After the endoscope is measured at two different positions in the measurement direction, the computer combines the image information and position information of the two measurements before and after to obtain the actual position information of the measured tiny parts. According to the aforementioned formula

In the formula, the positions I ₀ and I ₁ of the images of tiny parts relative to the center of the field of view of the camera are collected by a pair of digital cameras C in the two measurements before and after (that is, the first measurement and the second measurement, 5 and 6 in Figure 2). The obtained image information is obtained by image processing, and the position difference ΔX of the two measured endoscopes can be accurately measured by the grating ruler, thereby obtaining the actual position information of each ring piece and calculating the relative position between the ring pieces.

Claims (2)

1. An assembly measurement device for tiny parts in a narrow space based on an industrial endoscope, characterized in that: the assembly measurement device is composed of an endoscope detection device (1), a precision linear motion platform (2) and a computer (3) ; The endoscope detection device is composed of industrial endoscope (A), lens (B), digital camera or digital video camera (C) and light source (D); the precision linear motion platform for moving the endoscope detection device consists of a horizontal It is composed of precision linear guide rails (a), (b) and grating ruler (c) moving in the vertical direction; grating ruler and precision linear guide rail form a closed-loop control system. 2. the described device of claim 1 is used for the measurement method of tiny part assembly in the narrow space, is characterized in that following steps: The endoscope inspection device (1) transmits the collected assembly image information of tiny parts to the computer (3), and the computer (3) performs online processing on the images to obtain the position information of the image of the tiny parts in the image coordinate system of the camera field of view ; The position movement of the endoscope (A) is realized by the precision linear guide rail (a) moving in the horizontal direction and the precision linear guide rail (b) moving vertically with the addition of a grating ruler (c). The movement of the guide rail is controlled by a computer, and the internal The movement information of the speculum in the measurement direction (ie the vertical direction) is measured by the grating ruler (c) and transmitted to the computer (3); After the endoscope is measured at two different positions in the measurement direction, the computer combines the image information and position information of the two measurements before and after to obtain the actual assembly position information of the measured tiny parts; according to the formula In the formula, the position I ₀ and I ₁ of the image of the tiny part relative to the center of the camera field of view in the two measurements before and after is obtained by image processing of the image information of the tiny part collected by the digital camera, and the position difference between the two measurements of the endoscope before and after ΔX is accurately measured by the grating ruler.

Images