1. An industrial line scanning camera measuring device for measuring the size of a workpiece is characterized in that: the device comprises two sets of camera components, a conveyor belt and a trigger mechanism; the camera assemblies respectively comprise a box with an opening at one end, a line scan camera, a light source and a distance adjusting structure, the line scan camera is slidably arranged in the box through the distance adjusting structure and collects images through the opening, and the light source is arranged in the box and is positioned above the line scan camera; the two sets of camera assemblies are respectively arranged above and on the side of the conveyor belt and used for respectively acquiring the length, the width and the height of a workpiece of the conveyor belt, and the triggering mechanism senses the workpiece and is in control connection with the light source; the camera assembly located on the side of the conveyor belt performs background segmentation according to a line scanning image obtained actually, the number of pixels is scanned line by line and an average value is taken to obtain the height of the workpiece, then the workpiece with the measured height is mapped and calibrated with the image pixels to obtain calibration parameters, and the height of the subsequent workpiece is measured through the calibration parameters; the camera assembly positioned above the conveyor belt measures the length of the workpiece by adopting the same method as the method for measuring the height of the camera assembly positioned on the side of the conveyor belt; and the camera assembly above the conveyor belt measures the distance between the data point and the width center by adopting a clustering method, removes data which are too large to deviate from the data point, extracts a plurality of positions from the measured width, and obtains the width of the workpiece by taking the mean value.

2. The industrial line scan camera measurement device for workpiece dimension measurement according to claim 1, wherein: the distance adjusting structure comprises a hand wheel, a lead screw, a guide rail and a sliding block, wherein the lead screw is rotatably installed on the box through the hand wheel, the sliding block is arranged on the lead screw and the guide rail in a sliding mode, the line scanning camera is installed on the sliding block, and the line scanning camera is arranged in the box through rotating the hand wheel.

3. The industrial line scan camera measurement device for workpiece dimension measurement according to claim 1, wherein: the trigger mechanism comprises an infrared sensor, and when a workpiece passes through the infrared sensor, the infrared sensor is triggered to turn on the light source.

4. The industrial line scan camera measurement device for workpiece dimension measurement according to claim 1, wherein: the light source comprises two strip-shaped LEDs which are distributed oppositely at an angle of 45 degrees, and the two LEDs are respectively positioned on two sides above the line scanning camera.

5. The industrial line scan camera measurement device for workpiece dimension measurement according to claim 1, wherein: the other end of the box opposite to the opening is also provided with an opening, and the circuit is connected out from the opening.

Background

With the continuous improvement of the automation degree of enterprises and the stricter control requirement on the quality, the machine vision is urgently needed to replace manual detection, and tasks which are difficult to realize manually, especially workpiece detection tasks under the conditions of high labor intensity and severe environment, can be finished by adopting the machine vision. Currently, industrial production in china is moving from relying on cheap labor to higher degree of automation, however, the degree of automation of industrial equipment in early stages of china is generally low, and for these equipment and traditional manual operation, a large number of updates are required, which brings large market demands for automation equipment including machine vision.

Differentiated according to camera sensor architecture, industrial machine vision systems can be divided into Area-scan (Area-scan) and Line-scan (Line-scan). The surface scanning is suitable for static imaging with fixed size, the image acquisition can be completed by one-time exposure, and the line scanning is used for continuously moving objects or occasions requiring continuous high-resolution imaging. The area-array camera is cheap, and at present, most of image detection systems on the market adopt an area-array scanning mode, but the outstanding defect is that the imaging range is limited. Therefore, the area-array camera can only be used for defect detection and size measurement of small-sized workpieces.

Industrial production often requires measurement in the face of very large size materials, and for workpieces having a size of more than one meter, inspection and measurement are often performed using line scan cameras. However, since industrial line scan cameras and lenses are very expensive and have low market popularity, the related art is not perfect. At present, in the market, a dispersed purchase scheme is adopted for an industrial linear scanning camera machine vision system, instruments and equipment such as a camera, a lens and a light source need to be purchased respectively, the coordination difficulty among different equipment is increased, the hardware parameter adjustment of the system is very complicated, and the dispersed equipment needs to be tested repeatedly to determine whether the model is suitable or not, so that the system cost is increased. Meanwhile, as no universal system standard exists, an integrated system detection scheme with stability, reliability and consistent performance is difficult to form. Therefore, how to effectively integrate all functional components of the industrial linear scanning camera system and form a unified and complete system solution becomes a key problem to be solved urgently in the current industrial automatic production, especially in the detection of large-size workpieces.

Disclosure of Invention

Aiming at the problems of inconvenient parameter adjustment, numerous interfaces, complex configuration and the like existing in the current linear scanning industrial camera during workpiece detection, the invention provides a complete set of industrial linear scanning machine vision solution, integrates the functions of image acquisition, light source configuration and triggering, movement mechanism focusing and the like of the linear scanning camera into one device, and provides measurement methods adopted by the device at different stations during actual measurement of the size of a workpiece.

The technical scheme adopted by the invention for solving the technical problems is as follows:

an industrial line scanning camera measuring device for measuring the size of a workpiece comprises two sets of camera components, a conveyor belt and a trigger mechanism; the camera assemblies respectively comprise a box with an opening at one end, a line scan camera, a light source and a distance adjusting structure, the line scan camera is slidably arranged in the box through the distance adjusting structure and collects images through the opening, and the light source is arranged in the box and is positioned above the line scan camera; the two sets of camera assemblies are respectively arranged above and on the side of the conveyor belt and used for respectively acquiring the length, the width and the height of a workpiece of the conveyor belt, and the triggering mechanism senses the workpiece and is in control connection with the light source; the camera assembly located on the side of the conveyor belt performs background segmentation according to a line scanning image obtained actually, the number of pixels is scanned line by line and an average value is taken to obtain the height of the workpiece, then the workpiece with the measured height is mapped and calibrated with the image pixels to obtain calibration parameters, and the height of the subsequent workpiece is measured through the calibration parameters; the camera assembly positioned above the conveyor belt measures the length of the workpiece by adopting the same method as the method for measuring the height of the camera assembly positioned on the side of the conveyor belt; and the camera assembly above the conveyor belt measures the distance between the data point and the width center by adopting a clustering method, removes data which are too large to deviate from the data point, extracts a plurality of positions from the measured width, and obtains the width of the workpiece by taking the mean value.

In another preferred embodiment, the distance adjustment structure comprises a handwheel, a lead screw rotatably mounted on the box by the handwheel, a guide rail and a slider sliding on the lead screw and the guide rail, the line scan camera being mounted on the slider and moving within the box by rotating the handwheel.

In another preferred embodiment, the trigger mechanism includes an infrared sensor that is triggered to turn on the light source when the workpiece passes by the infrared sensor.

In another preferred embodiment, the light source includes two strip-shaped LEDs oppositely distributed at an angle of 45 degrees, and the two LEDs are respectively located at two sides above the line scan camera.

In another preferred embodiment, the other end of the box opposite to the opening is also provided with an opening, and the circuit is connected out from the opening.

The invention has the beneficial effects that:

(1) the scheme adopts an integrated design method, integrates the functions of image acquisition, light source configuration and triggering, movement mechanism focusing and the like of a line scanning camera into one device, and is very convenient for parameter setting and adjustment.

(2) The light source in the vision system adopts an external trigger control mechanism, so that the service life of the light source is prolonged.

(3) The method adopts a manual focusing mode, reduces the requirements of a vision system on a camera and a lens, only needs to adopt a common line scanning camera and a fixed-focus lens, and has the total cost which can be controlled within 1.5 ten thousand and low price.

(4) According to the workpiece measurement of the device at different stations, different measurement strategies are provided, and the method is simple and easy to implement.

The invention is further explained in detail with the accompanying drawings and the embodiments; however, an industrial line scan camera measuring device for measuring a dimension of a workpiece according to the present invention is not limited to the embodiment.

Drawings

Fig. 1 is a schematic structural diagram of an industrial line scan camera measuring device according to a preferred embodiment of the invention.

Fig. 2 is a top view of one of the camera assemblies of fig. 1.

Detailed Description

In an embodiment, referring to fig. 1, an industrial line scan camera measuring device for measuring the size of a workpiece according to the present invention includes two sets of camera assemblies 1 and 2, a conveyor belt 3 and a trigger mechanism 4; two sets of camera assemblies 1 and 2 are identical in structure, as shown in fig. 2, taking one set of camera assembly 1 as an example, the camera assembly 1 includes a box 1-1 with two open ends, a line scan camera 1-2, a light source 1-3 and a distance adjusting mechanism, the distance adjusting mechanism includes a hand wheel 1-41, a lead screw 1-42, a guide rail 1-43 and a slider 1-44, the lead screw 1-42 is rotatably mounted on the box 1-1 through the hand wheel 1-41, the slider 1-44 slides on the lead screw 1-42 and the guide rail 1-43, the line scan camera 1-2 is mounted on the slider 1-44, the line scan camera 1-2 moves in the box 1-1 through rotating the hand wheel 1-41, therefore, the line scan camera 1-2 is slidably mounted on the box 1 through the distance adjusting mechanism 1, and through the opening, the light source 1-3 is installed at the light source 1-3, and the light source 1-3 comprises two strip-shaped LEDs which are distributed oppositely at an angle of 45 degrees, and the two LEDs are respectively positioned at two sides above the line scanning camera 1-2.

In this embodiment, two sets of camera assemblies 1 and 2 are respectively installed above and at the side of the conveyor belt 3 to respectively acquire the length, the width and the height of the workpiece 100 of the conveyor belt, and the triggering mechanism 4 includes an infrared sensor which senses the arrival of the workpiece and starts the light sources 1 to 3.

The structural features of the camera assembly will be described in more detail below. In the embodiment, a rectangular iron metal box is selected as the box of the camera component, the light source, the line scanning camera and the screw rod are arranged in the box, two ends of the box are opened, the light source is arranged at the top end of one end of the box and used for workpiece illumination, and a light source controller (not shown in the figure) can be arranged at the upper part of the box.

The wiring of the line scanning camera and the light source is led out from the other end of the box, so that parameters can be conveniently debugged.

The black matt paint is selected for the color of the box, so that image segmentation processing during visual inspection is facilitated, the matt paint is selected for the purpose that when a plurality of the device are used in a combined mode, a plurality of light sources interfere, the matt paint can well absorb light, and specular reflection is avoided.

Without loss of generality, the light source selects white strip LED, is 45 degrees angle two sides and arranges along 2mm departments at the distance box outer end, and the purpose of light source symmetry angle installation makes the line scan camera two-sided when scanning the work piece polish, avoids one side light that the unilateral was polished and is brought strong, the dark problem of one side light, and light is even.

The light source controller adopts a triggerable type, a connecting line of a triggering mechanism is connected with control equipment such as a PLC (programmable logic controller), a single chip microcomputer and the like, and whether a light source is turned on or not is determined according to whether an infrared sensor or other sensors sense that a workpiece arrives or not. The purpose of selecting the external trigger light source is to adjust the brightness of the light source to be very high in the line scanning camera system in order to ensure the accuracy of workpiece detection and measurement, so that the heat productivity of the light source is very large, the long-time service life is reduced, the trigger type light source is adopted, the light source is turned on only when the workpiece approaches the line scanning camera, the turn-on time of the light source is reduced, the service life of the light source is relatively prolonged, and the loss cost of the system is reduced.

The industrial line camera is installed on the sliding block of the screw rod, the handle capable of rotating is installed outside the screw rod, the distance between the camera and a workpiece can be adjusted by adjusting the handle, and focusing and adjusting of the aperture size of the camera are facilitated.

Therefore, due to the fact that the triggerable light source structure is adopted, the brightness of the light source can be adjusted to be high, the requirement for camera hardware is reduced, and the line scanning camera can be achieved by adopting a common industrial line scanning camera. Meanwhile, the camera is arranged on an adjustable structure of an adjustable longitudinal movement lead screw, so that the visual system can be manually focused, and the camera lens is a fixed focal length lens, so that the cost of the visual system is further reduced.

The following describes in detail the workpiece measurement method of the present embodiment at different stations:

the device can be used for workpiece measurement and can be divided into two modes of vertical arrangement and lateral arrangement. The line scan camera (camera module 2) is perpendicular to the moving direction of the conveyor belt 3 when vertically arranged to measure the length and width of the workpiece 100, and the line scan camera (camera module 1) is located at the side of the conveyor belt 3, perpendicular to the side of the workpiece 100, to measure the height of the workpiece 100 when laterally arranged.

1) When the line scan camera is arranged laterally (the camera component 1), because the vision measurement system has no interference of motion factors in the longitudinal direction, the background segmentation can be carried out according to the actually obtained line scan image, the number of pixels is scanned line by line and the average value is taken to obtain the height (pixel unit) of the workpiece, then the workpiece (actual physical size) with the measured height is mapped and calibrated with the image pixels to obtain calibration parameters, and the parameters can be directly used for measuring the height of the subsequent workpiece.

2) When the line scan cameras are vertically arranged (the camera assemblies 2), the line scan measuring system must use the movement speed to obtain images, and the industrial production line mostly adopts the movement mode of the conveyor belt, and the movement mode of the conveyor belt is simple and easy, but slight shake caused by belt looseness and the like exists in the process of conveying workpieces. The workpiece length of the line scanning measurement system is very long, the influence of the jitter on the length is very little, but the width of the workpieces to be measured is limited due to the limitation of the size of the conveyor belt, the influence of the jitter on the width is certain, and if the pixels which can be used for measurement have jitter, the instability of the width measurement result is caused.

The problems of the vertical arrangement of the line-scan camera are caused by the instability of the sensing mechanism and the movement mechanism of the line-scan camera, and the device cannot eliminate focusing, resolution modification or light-emitting mode change no matter how, so that the device still performs measurement in a height measurement mode in the length direction when being vertically arranged; for the width direction with disturbance, firstly, the distance between a data point and the width center is measured by using a clustering method, data deviating from the data point to be too large is removed, then, ten positions are extracted from the measured width, and the width result is obtained by taking the mean value. Although the measuring mechanism cannot eliminate the influence caused by jitter errors, the interference caused by the errors on the measurement is well suppressed. If the jitter disturbance is not counted, random errors are brought to the measurement results, if the measurement results are directly averaged, the measurement results are possibly inaccurate due to overlarge random jitter data points, and the data points are preferably selected firstly, and then the error can be stabilized within a certain range by means of averaging. Through actual measurement, the width error can be controlled within 0.5mm by adopting the method.

The invention has the following remarkable characteristics:

(1) the scheme adopts an integrated design method, integrates the functions of image acquisition, light source configuration and triggering, movement mechanism focusing and the like of a line scanning camera into one device, and is very convenient for parameter setting and adjustment.

(2) The light source in the vision system adopts an external trigger control mechanism, so that the service life of the light source is prolonged.

(3) The method adopts a manual focusing mode, reduces the requirements of a vision system on a camera and a lens, only needs to adopt a common line scanning camera and a fixed-focus lens, and has the total cost which can be controlled within 1.5 ten thousand and low price.

(4) According to the workpiece measurement of the device at different stations, different measurement strategies are provided, and the method is simple and easy to implement.

The above embodiments are merely provided to further illustrate the industrial line scan camera measuring device for measuring the dimension of a workpiece according to the present invention, but the present invention is not limited to the embodiments, and any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical spirit of the present invention fall within the scope of the technical solution of the present invention.