A machine vision and scanning detection device and its working method

Abstract

The present invention relates to a machine vision and scanning detection device and its working method, which includes a detection table. A perspective hole is vertically penetrated through the detection table. A backlight source is erected directly below the detection table opposite to the perspective hole. A transparent platform is fixedly arranged on the upper surface of the detection table directly above the perspective hole. A second camera is erected directly above the transparent platform. A first camera is erected on one side of the second camera at a certain angle with the second camera and aligned with the transparent platform. A structured light scanning mechanism is erected on the other side of the second camera at a certain angle with the second camera and aligned with the transparent platform. A movable fixture is arranged on the front side of the detection table, and the movable fixture extends to the transparent platform for limiting. A three-axis motion platform is installed on the rear side of the detection table, and a probe is fixedly arranged on the Z-axis of the three-axis motion platform. The structure of the machine vision and scanning detection device is reasonable, which solves the problems of narrow adaptation range of single vision or scanning detection method for a long time, low scanning detection efficiency, and inconvenient clamping, positioning and picking and placing of parts.

Description

Technical Field

[0001] The present invention relates to the technical field of part dimension detection, and is a machine vision and scanning detection device and its working method. Background Art

[0002] At present, there are various automated detection methods for parts, but each detection method has many limitations, so that multiple detection processes are required to detect a part, and different detection instruments are needed to complete it. Specifically as follows:

[0003] The detection efficiency of monocular vision and binocular vision is very high, but the material and surface characteristics of the part itself (such as whether it is smooth, whether it is a curved surface, the degree of reflection, surface texture, etc.) have a great impact on the accuracy of the detection result. Parts with different materials and surface characteristics need to use different types and structures of light sources, and the lighting angles and directions are also different, so the general performance of the light source is very poor; so far, only the part size parameters that can be detected by the backlight projection method in monocular vision have practical value. The accuracy of binocular vision is not high and can only be applied to occasions with low accuracy requirements, and the accuracy seriously depends on the surface texture. The more complex the surface texture, the higher the accuracy; in addition, ambient light has a great impact on the detection results of monocular vision and binocular vision.

[0004] Structured light scanning is affected by the resolution of structured light. At present, the accuracy of the part in the Z direction can be very high, but the accuracy in the horizontal X and Y directions is not high, and it is also affected by ambient light.

[0005] The accuracy in the X, Y, and Z directions of coordinate measurement can be very high, but the efficiency is very low. The measurement accuracy depends on the accuracy of the X, Y, and Z axis motion platforms, the probe, and the algorithm. Therefore, the accuracy requirements for the X, Y, and Z axis motion platforms and the probe are very high, and the manufacturing cost and difficulty are relatively high, and the requirements for the use environment are also very high; when using coordinate measurement for continuous contour scanning, a continuous contour scanning probe is required. The continuous contour scanning probe needs to perform complex detection on the azimuth change of the probe needle or probe ball, and use a complex algorithm to obtain the actual contour of the part, and the cost is expensive.

[0006] Methods such as camera focus measurement, laser interferometry measurement, laser flight measurement, spectral aggregation measurement, electromagnetic induction measurement, and eddy current measurement all have the problems of single measurable parameters and low detection efficiency.

[0007] During the detection process, the clamping, picking and placing, and positioning of parts take a long time. The shapes of parts are various, which brings great difficulties to the clamping and positioning of parts. Summary of the Invention

[0008] In view of the deficiencies of the prior art, the technical problem to be solved by the present invention is to provide a machine vision and scanning detection device and its working method, which not only has a reasonable structure, but also effectively solves the problems of narrow adaptation range of the long-term single vision or scanning detection method, low scanning detection efficiency, and inconvenient clamping, positioning and picking and placing of parts.

[0009] To solve the above technical problems, the technical solution of the present invention is: a machine vision and scanning detection device, including a detection table, a perspective hole is vertically penetrated through the detection table, a backlight is erected right below the detection table opposite to the perspective hole, a transparent platform is fixedly arranged on the upper surface of the detection table directly above the perspective hole, a second camera is erected directly above the transparent platform, a first camera is erected on one side of the second camera at a certain angle with the second camera and aligned with the transparent platform, a structured light scanning mechanism is erected on the other side of the second camera at a certain angle with the second camera and aligned with the transparent platform, a movable fixture is arranged on the front side of the detection table, and the movable fixture extends to the transparent platform for limiting, and a three-axis motion platform is installed on the rear side of the detection table, and a probe is fixedly arranged on the Z-axis of the three-axis motion platform.

[0010] Furthermore, the backlight and the second camera form a backlight projection measurement unit, which has the characteristics of high efficiency and high precision and is suitable for measurement parameters that can use backlight projection measurement; the first camera, the second camera, the three-axis motion platform and the probe form a binocular scanning measurement unit, which has the characteristics of high efficiency, high precision, small influence of ambient light, and a wide range of adaptable measurement parameters, including measuring curved surfaces and continuous contour scanning; it can cooperate with the backlight projection measurement unit or the structured light scanning measurement unit to perform high-precision reverse modeling; the second camera and the structured light scanning mechanism form a structured light scanning measurement unit, which is suitable for performing high-precision Z-direction measurement. The three measurement units can be used separately or in combination, greatly broadening the adaptability and general performance of the automated detection system.

[0011] Furthermore, the probe includes a housing, the outer wall of the housing is fixedly connected to the Z-axis, an outer tubular permanent magnet is embedded near the lower end of the inner wall of the housing, a lower annular permanent magnet is embedded above the outer tubular permanent magnet on the inner wall of the housing, and an upper annular permanent magnet is embedded above the lower annular permanent magnet on the inner wall of the housing; a measuring rod penetrates through the center of the inner wall of the housing, a measuring ball is arranged at the lower end of the measuring rod, the top of the measuring rod extends out of the housing and is provided with a light source support plate, three planar light sources are evenly distributed along the circumference of the light source support plate, a lithographic transparent standard circle is installed on each of the planar light sources, a suspended annular permanent magnet is installed on the measuring rod below the support plate, and the suspended annular permanent magnet is located between the upper annular permanent magnet and the lower annular permanent magnet; an inner tubular permanent magnet is sleeved on the measuring rod in the outer tubular permanent magnet, and the inner tubular permanent magnet is fixedly connected to the measuring rod, and the inner diameters of the upper annular permanent magnet and the lower annular permanent magnet are both larger than the diameter of the measuring rod, and the inner diameter of the outer tubular permanent magnet is larger than the outer diameter of the inner tubular permanent magnet to ensure the swing range of the measuring rod.

[0012] Further, the polarities of the outer tubular permanent magnet and the inner tubular permanent magnet are the same at the adjacent positions, and the polarities of the suspended annular permanent magnet and the upper and lower annular permanent magnets are the same at the adjacent positions.

[0013] Further, the probe head is designed based on the principle of magnetic levitation. When the measuring ball touches the surface of the part, the measuring rod and the lithographic transparent standard circle on it swing within a certain three-dimensional space range. The binocular scanning measurement unit calculates the coordinates of the center of the measuring ball through the change of the position coordinates of the three lithographic transparent standard circles, and then detects the measurement parameters of the part. The accuracy of the binocular scanning measurement unit depends on the accuracy of the camera lens and the calibration accuracy of the probe head, and has a very small correlation with the accuracy of the motion platform. The three-axis motion platform is only used to drive the probe head to scan on a rough scanning trajectory. The magnetic levitation structure ensures that the measuring ball is always in contact with the surface of the part during the scanning process, greatly reducing the requirement for the accuracy of the motion platform compared with the three-coordinate measuring machine. Compared with the existing trigger-type probe head and scanning-type probe head, especially the scanning-type probe head, the probe head designed based on the magnetic levitation principle has a relatively simple structure, greatly reducing the manufacturing and maintenance costs. With the existing technical means, the accuracy of the lithographic transparent standard circle can be made very high, and a very high calibration accuracy can be achieved by using the existing calibration algorithm. The lithographic transparent standard circle has its own light source, which is equivalent to a self-luminous light source, so it can also greatly reduce the influence of ambient light on the measurement accuracy. Due to the interference and delay effects of the mechanical structure, electronic circuit, and signal line of the existing trigger-type probe head and scanning-type probe head, high accuracy can only be achieved through complex software algorithms. At present, the shooting speed of high-speed cameras can be made very high, and its response speed can reach or exceed the response speed of the existing probe head. The binocular vision detection standard circle algorithm is simple. Therefore, compared with the three-coordinate measurement, the binocular scanning measurement unit can achieve the measurement accuracy of the three-coordinate measuring machine, and the efficiency is much higher than that of the three-coordinate measuring machine.

[0014] Further, a waveform spring fixing ring is fixedly arranged on the inner wall of the housing between the upper and lower annular permanent magnets. A waveform spring is installed inside the waveform spring fixing ring, and two passive contact rings are arranged at intervals on the waveform spring. An active contact ring is fixedly arranged circumferentially on the suspended annular permanent magnet. The housing is provided with upper safety contact plates, upper safety contacts, lower safety contact plates, and lower safety contacts in pairs horizontally from the outer wall to the inner wall. The upper safety contact plates and the upper safety contacts are parallel to each other and are located above the suspended annular permanent magnet. The lower safety contact plates and the lower safety contacts are parallel to each other and are located below the suspended annular permanent magnet.

[0015] Further, the upper safety contact bends upward into an arc-shaped convex shape directly above the active contact ring to form a contact point that cooperates with the upper safety contact plate, and the lower safety contact bends downward into an arc-shaped convex shape directly below the active contact ring to form a contact point that cooperates with the lower safety contact plate.

[0016] Further, two passive contact rings, an upper safety contact plate, upper safety contacts, a lower safety contact plate, and lower safety contacts that are spaced apart on the wave spring are respectively connected to the controller. Once due to misoperation or equipment failure, the measuring rod exceeds the allowable range of movement, or the active contact ring contacts the two passive contact rings simultaneously, or the upper safety contact plate contacts the upper safety contacts, or the lower safety contact plate contacts the lower safety contacts, the circuit can be connected to generate a switch signal, causing the three-axis motion platform to stop moving, achieving the purpose of protecting the probe head; adopting a scheme of using one active contact ring to contact the two passive contact rings to generate a connection signal enables the signal line to be connected only to the two passive contact rings. The above structure is simple, durable, and has stable performance.

[0017] Further, the movable fixture includes a rotating table, a jaw cylinder is installed on the rotating table, concave supports vertically arranged are respectively fixed on the two jaws of the jaw cylinder, a slide rail is vertically arranged on the concave support, a slider that is slidably matched with the slide rail and can elastically lift is arranged on the slide rail, a clamping arm is arranged at the rear end of the slider, both clamping arms extend horizontally backward, and a plurality of annular springs are symmetrically arranged on the inner sides of the rear ends of the two clamping arms.

[0018] Further, vertical springs are respectively fixed on the upper and lower parts inside the concave support, and the other ends of the vertical springs are respectively fixedly connected to the end faces on the corresponding sides of the slider; a fixed block is connected to the rear end of the slider, a slot for the front end of the clamping arm to be inserted into is arranged at the rear side of the fixed block, and a locking bolt for locking the clamping arm is arranged on the fixed block; there are four annular springs, and they are arranged at intervals of two on the inner side wall of the rear end of the clamping arm.

[0019] Further, the movable fixture can realize functions of clamping, flipping, and adapting to the transparent platform for parts, enabling good contact between the bottom surface of the part and the transparent platform; adapting to parts with different shapes, making the clamping of parts stable and reliable; the clamping part of the fixture adopts an arc structure, and the part and the fixture have more than three contact points, which can ensure stable and reliable clamping of the part and minimize the impact of the fixture on visual inspection; as for the movable fixture can be adjusted up and down through a jacking mechanism to cooperate with the rotating table to realize the flipping of parts, which is a conventional design and will not be elaborated here too much.

[0020] Further, the structured light scanning mechanism includes a structured light scanning axis, a structured light bracket is installed on the structured light scanning axis, a structured light is connected to the side of the structured light bracket through a structured light fixing ring, and the structured light passes through the structured light fixing ring and is fixed.

[0021] Further, currently, the structured light manufacturing technology cannot achieve a very high resolution, resulting in the inability to improve the accuracy of the structured light in the X and Y directions. In the present invention, the structured light is placed on a high-precision scanning axis, and the scanning axis drives the structured light to continuously scan the surface of the part to obtain more scanning points, which can improve the scanning accuracy.

[0022] A working method for a machine vision and scanning detection device is carried out according to the following steps: Step S1: Camera model calibration: Calibrate the second camera lens to establish the parameters of the backlight projection model; calibrate the first camera lens and the second camera lens to establish the parameters of the binocular vision three-dimensional projection model; calibrate the second camera lens and the structured light scanning mechanism to establish the parameters of the structured light vision three-dimensional scanning model; when calibrating, calibrate the three projection model parameters to the same reference coordinate system; Step S2: Calibration of the conversion parameters between the backlight projection image coordinate system and the motion platform coordinate system: Place a standard optical flat ring gauge on the transparent platform, measure the circular contour C1 of the working surface of the standard optical flat ring gauge with the backlight projection measurement unit, manually control the motion platform to scan the circular contour of the ring gauge working surface, and calculate the center coordinates [C 1x , C 1y and the center coordinates [V 1x , V 1y of the scanning trajectory. Repeat the above steps 2 times, place the optical flat ring gauge at different positions on the transparent platform for detection and scanning respectively, and obtain the center coordinates [C 2x , C 2y , [C 3x , C 3y of the circular contours at the other 2 positions of the optical flat ring gauge and the center coordinates [V 2x , V 2y , [V 3x , V 3y of the scanning trajectories. Use 2 corresponding pairs of four-point coordinates, [C 1x , C 1y , [C 2x , C 2y and [V 1x , V 1y , [V 2x , V 2y to calculate the translation and rotation parameters p1, m1 from the backlight projection image coordinate system to the motion platform coordinate system. To determine whether it is a left-handed coordinate system or a right-handed coordinate system, then use the input order of [C 2x , C 2y , [C 1x , C 1y and [V 1x , V 1y , [V 2x , V 2y to calculate the translation and rotation parameters p2, m2 of the conversion coordinate system. Then convert [C 3x , C 3y using the translation and rotation parameters calculated twice, and compare the x and y coordinates of the results of the two conversions with [V 3x , V 3yTake the absolute value of the difference between the x and y values of [], and use the translation and rotation parameters and the input order of the backlight projection image coordinates for the translation and rotation with the smaller absolute value as the input order of the translation and rotation parameters and the coordinate points during conversion;

[0023] Step S3: Calibrate the conversion parameters between the structured light vision three-dimensional coordinate system and the motion platform coordinate system. Use the backlight projection model and the binocular vision three-dimensional projection model to calibrate the distance from the centers of the three lithographic transparent standard circles of the probe to the center of the probe ball: Place a smooth ring gauge on the transparent platform, detect the working surface circle contour of the ring gauge through backlight projection, and calculate the center XY coordinates [C1_X, C1_Y] of the circle contour and the series of XY coordinates [X i , Y i of the scanning trajectory along the circle contour. Convert the series of XY coordinates of the scanning trajectory to the motion platform coordinates. The three-axis motion platform drives the probe ball to contact both the working surface of the ring gauge and the transparent platform simultaneously and move along the series [X i , Y iCoordinate scanning: The binocular vision system simultaneously tracks three lithography transparent standard circles above the probe, calculates a series of three-dimensional center coordinates of these standard circles, fits these series of three-dimensional center coordinates into three circles, and obtains the three-dimensional center coordinates of these three circles: [C2_X, C2_Y, C2_Z], [C3_X, C3_Y, C3_Z], [C4_X, C4_Y, C4_Z]. Since the probe ball contacts the working surface of the ring gauge and the transparent platform simultaneously during scanning, the Z coordinate of the center XY coordinates [C1_X, C1_Y] calculated from the circle contour is the radius R of the probe ball. Thus, the three-dimensional coordinates of the probe ball center corresponding to [C2_X, C2_Y, C2_Z], [C3_X, C3_Y, C3_Z], [C4_X, C4_Y, C4_Z] are [C1_X, C1_Y, R]. According to the distance formula between points in three-dimensional space, equations can be listed to find the distances d1, d2, d3 from [C2_X, C2_Y, C2_Z], [C3_X, C3_Y, C3_Z], [C4_X, C4_Y, C4_Z] to [C1_X, C1_Y, R], which are the distances from the centers of the three lithography transparent standard circles to the probe ball center; Step S4: Binocular vision scanning measurement method: While scanning, the binocular vision tracks three lithography transparent standard circles above the probe and calculates a series of three-dimensional center coordinates of these standard circles. Since the distances from the center coordinates to the probe ball center have been obtained through calibration, according to the distance formula between points in three-dimensional space, the three-dimensional coordinates of the probe ball center corresponding to the center coordinates of the three lithography transparent standard circles can be calculated, and then the actual measurement parameters can be calculated based on the probe ball radius; If the actual scanning trajectory coordinates of the part are to be obtained, then according to the type of scanning trajectory, the series of three-dimensional coordinates of the calculated probe ball centers are fitted into contours corresponding to the type of scanning trajectory, such as a straight line, a circle, an ellipse, or a curve. Since the fitted contour is parallel to the actual contour of the part and the distance is equal to the probe ball radius, the actual contour of the part can be obtained.

[0024] Step S5: Process of measuring parts: The movable fixture picks up the parts to the transparent platform, and selects one or more of backlight projection, binocular vision, and structured light scanning according to the characteristics of the parts and dimensions, accuracy requirements, etc. for combined measurement. After the measurement is completed, the movable fixture rises, rotates 180 degrees, and then descends to the transparent platform for measurement on the other side. After both sides are measured, classification is performed according to the detection results, and the movable fixture places the detected parts at the specified positions. When using binocular vision scanning measurement, if there is a CAD drawing, the scanning path can be preset, and the CAD drawing is matched with the actual contour of the parts obtained by backlight projection or structured light scanning to obtain the transformation relationship matrix between the coordinates of the CAD drawing and the coordinate system of backlight projection or structured light scanning. The scanning path coordinates are converted to the coordinate system of backlight projection or structured light scanning by this matrix, and then converted to the coordinate system of the moving platform according to the coordinate system transformation matrix between the backlight projection or structured light scanning coordinate system and the moving platform coordinate system for scanning. If there is no CAD drawing, the path to be scanned can be detected first by backlight projection or structured light scanning and then binocular vision scanning measurement can be performed.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The three measurement units of backlight projection, binocular scanning, and structured light scanning can work independently or cooperate with each other. One or several detection units can be selected for combination detection according to different part materials and surface characteristics, giving full play to the advantages of each measurement unit, greatly broadening the adaptability and versatility of the automated detection system, and significantly reducing the detection processes of building an automated detection pipeline.

[0027] 2. The binocular scanning measurement unit cleverly combines the three-coordinate measurement principle and the binocular vision measurement principle to create a new measurement method whose measurement accuracy is independent of the accuracy of the measurement moving platform and the probe. While significantly reducing the manufacturing cost and assembly complexity, it simultaneously realizes the advantages of high accuracy of three-coordinate measurement and high efficiency of binocular vision measurement.

[0028] 3. The probe is designed based on the magnetic levitation principle, with simple structure, easy implementation, and low cost; the lithographic transparent standard circle has simple visual detection, its own light source is not easily affected by ambient light, and the detection performance is stable.

[0029] 4. The calibration can be used permanently once, and only needs to be recalibrated after replacing the accessories related to the measurement unit.

[0030] 5. Both the system calibration method and the measurement calculation method can adopt existing mature methods, which are easy to implement and simple to operate.

[0031] 6. The movable fixture can be installed on the part transfer manipulator to realize the functions of automatic clamping, picking, placing, transferring and sorting of parts, enabling the system to be installed on the existing production line for on-line detection, greatly reducing the cost and complexity of the automatic detection line, and can also be used as an independent detection line. It well solves the difficulties and pain points in the current field of automatic detection while reducing the manufacturing cost and the difficulty of detection algorithms, and has broad application prospects.

[0032] The following further describes the present invention in detail with reference to the accompanying drawings and specific embodiments. Description of the Drawings

[0033] Figure 1 It is a schematic structural diagram of an embodiment of the present invention;

[0034] Figure 2 It is a bottom view schematic diagram of an embodiment of the present invention;

[0035] Figure 3 It is a top view schematic diagram of an embodiment of the present invention;

[0036] Figure 4 It is a schematic structural diagram of the probe in an embodiment of the present invention;

[0037] Figure 5 is Figure 4 a partial cross-sectional view of;

[0038] Figure 6 It is an installation schematic diagram of the wave spring in an embodiment of the present invention;

[0039] Figure 7 It is a schematic structural diagram of the movable fixture in an embodiment of the present invention;

[0040] Figure 8 The external view of the probe of the second embodiment of the present invention.

[0041] In the figure: 1 - inspection table, 101 - perspective hole, 102 - part, 2 - transparent platform, 3 - backlight, 4 - first camera, 5 - second camera, 6 - three-axis motion platform, 61 - X-axis, 62 - Y-axis, 63 - Z-axis, 7 - structured light scanning mechanism, 71 - structured light fixing ring, 72 - structured light, 73 - structured light scanning axis, 74 - structured light support, 8 - probe, 801 - probe ball, 802 - probe rod, 803 - housing, 804 - planar light source, 805 - lithography transparent standard circle, 806 - light source support plate, 807 - upper annular permanent magnet, 808 - upper safety touch plate, 809 - upper safety contact, 810 - lower safety touch plate, 811 - lower safety contact, 812 - wave spring fixing ring, 813 - wave spring, 814 - passive touch ring, 815 - active touch ring, 816 - suspended annular permanent magnet, 817 - lower annular permanent magnet, 818 - inner tubular permanent magnet, 819 - outer tubular permanent magnet, 9 - movable fixture, 901 - annular spring, 902 - slider, 903 - clamping arm, 904 - fixed block, 905 - locking bolt, 906 - jaw cylinder, 907 - concave support, 908 - rotating table, 909 - jaw, 910 - slide rail, 911 - vertical spring. Detailed implementation manners

[0042] To make the above features and advantages of the present invention more obvious and understandable, specific embodiments are hereinafter given and described in detail in conjunction with the accompanying drawings as follows.

[0043] As Figures 1 to 8 shown, a machine vision and scanning detection device includes an inspection table 1. A perspective hole 101 runs through the inspection table vertically. A backlight 3 is installed directly below the inspection table opposite to the perspective hole. A transparent platform 2 is fixedly installed on the upper surface of the inspection table directly above the perspective hole. A second camera 5 is installed directly above the transparent platform. A first camera 4 is installed on one side of the second camera at a certain angle with respect to the second camera and aligned with the transparent platform. A structured light scanning mechanism 7 is installed on the other side of the second camera at a certain angle with respect to the second camera and aligned with the transparent platform. A movable fixture 9 is arranged on the front side of the inspection table, and the movable fixture extends to the transparent platform for limiting. A three-axis motion platform 6 is installed on the rear side of the inspection table, and a probe 8 is fixedly installed on the Z-axis 63 of the three-axis motion platform.

[0044] In an embodiment of the present invention, the probe head includes a housing 803, the outer wall of the housing is fixedly connected to the Z-axis, an outer tubular permanent magnet 819 is embedded near the lower end of the inner wall of the housing, a lower annular permanent magnet 817 is embedded above the outer tubular permanent magnet on the inner wall of the housing, and an upper annular permanent magnet 807 is embedded above the lower annular permanent magnet on the inner wall of the housing; a measuring rod 802 penetrates through the center of the inner wall of the housing, a measuring ball 801 is provided at the lower end of the measuring rod, the top of the measuring rod extends out of the housing and is provided with a light source support plate 806, three planar light sources 804 are evenly distributed circumferentially along the light source support plate, a lithographic transparent standard circle 805 is installed on each of the planar light sources, a suspended annular permanent magnet 816 is installed on the measuring rod below the support plate, and the suspended annular permanent magnet is located between the upper annular permanent magnet and the lower annular permanent magnet; an inner tubular permanent magnet 818 is sleeved on the measuring rod inside the outer tubular permanent magnet, and the inner tubular permanent magnet is fixedly connected to the measuring rod.

[0045] In an embodiment of the present invention, the polarities of the outer tubular permanent magnet and the inner tubular permanent magnet at the proximity are the same, and the polarities of the suspended annular permanent magnet and the upper and lower annular permanent magnets at the proximity are the same.

[0046] In an embodiment of the present invention, a waveform spring fixing ring 812 is fixedly provided at the position between the upper and lower annular permanent magnets on the inner wall of the housing, a waveform spring 813 is installed inside the waveform spring fixing ring, and two passive contact rings 814 are arranged at intervals on the waveform spring; an active contact ring 815 is fixedly provided circumferentially on the suspended annular permanent magnet; the housing horizontally penetrates through the inner wall in pairs from the outer wall inward to be provided with an upper safety contact plate 808, an upper safety contact point 809 and a lower safety contact plate 810, a lower safety contact point 811, the upper safety contact plate and the upper safety contact point are parallel to each other and are located above the suspended annular permanent magnet, and the lower safety contact plate and the lower safety contact point are parallel to each other and are located below the suspended annular permanent magnet.

[0047] In an embodiment of the present invention, the upper safety contact point bends upward into an arc-shaped protrusion at the position directly above the active contact ring to form a contact point that cooperates with the upper safety contact plate, and the lower safety contact point bends downward into an arc-shaped protrusion at the position directly below the active contact ring to form a contact point that cooperates with the lower safety contact plate.

[0048] In an embodiment of the present invention, the movable fixture includes a rotating table 908, a jaw cylinder 906 is installed on the rotating table, concave supports 907 arranged vertically are respectively fixed on two jaws 909 of the jaw cylinder, a slide rail 910 is vertically arranged on the concave support, a slider 902 that is slidably matched with the slide rail and can elastically lift is arranged on the slide rail, a clamping arm 903 is arranged at the rear end of the slider, both clamping arms extend horizontally backward, and a plurality of annular springs 901 are symmetrically arranged on the inner sides of the rear ends of the two clamping arms.

[0049] In an embodiment of the present invention, vertical springs 911 are respectively fixed to the upper and lower parts inside the concave-shaped support, and the other ends of the vertical springs are respectively fixedly connected to the end faces on the corresponding sides of the slider; thereby, the elastic lifting of the slider is realized through the cooperation of the vertical springs and the slide rail, and then the elastic lifting of the clamping arm is realized, and the self-adaptation during the clamping of parts 102 with different outer shapes is completed in cooperation with the annular spring; a fixing block 904 is connected to the rear end of the slider, a slot for the front end of the clamping arm to be inserted is provided at the rear side of the fixing block, and a locking bolt 905 for locking the clamping arm is provided on the fixing block, so that the connection and fixation of the clamping arm and the fixing block are completed through the locking bolt; four annular springs are provided, and are arranged at intervals of two on the inner side wall of the rear end of the clamping arm.

[0050] In an embodiment of the present invention, the structured light scanning mechanism includes a structured light scanning shaft 73, a structured light support 74 is installed on the structured light scanning shaft, a structured light 72 is connected to the side of the structured light support through a structured light fixing ring 71, and the structured light is inserted into the structured light fixing ring and fixed.

[0051] A working method of a machine vision and scanning detection device is carried out according to the following steps:

[0052] Step S1: Camera model calibration: Calibrate the second camera lens to establish the parameters of the backlight projection model; calibrate the first camera lens and the second camera lens to establish the parameters of the binocular vision three-dimensional projection model; calibrate the second camera lens and the structured light scanning mechanism to establish the parameters of the structured light vision three-dimensional scanning model; when calibrating, calibrate all three projection model parameters to the same reference coordinate system.

[0053] Step S2: Calibration of the conversion parameters between the backlight projection image coordinate system and the moving platform coordinate system: Place a standard optical flat ring gauge on the transparent platform, measure the circular contour C1 of the working surface of the standard optical flat ring gauge with the backlight projection measurement unit, manually control the moving platform to scan the circular contour of the ring gauge working surface, and calculate the center coordinates [C 1x , C 1y of the C1 circular contour and the center coordinates [V 1x , V 1y of the scanning trajectory. Repeat the above steps 2 times, place the optical flat ring gauge at different positions on the transparent platform for detection and scanning respectively, and obtain the center coordinates [C 2x , C2 y , [C 3x , C 3y of the circular contours at the other 2 positions of the optical flat ring gauge and the center coordinates [V 2x , V 2y , [V 3x , V 3y of the scanning trajectories. Use 2 pairs of corresponding four-point coordinates among them, [C 1x , C1y , [C 2x , C 2y and [V 1x , V 1y , [V 2x , V 2y Calculate the translation and rotation parameters p1, m1 of the backlight projection image coordinate system to the motion platform coordinate system. To determine whether it is a left-handed coordinate system or a right-handed coordinate system, then use [C 2x , C 2y , [C 1x , C 1y 's input order and [V 1x , V 1y , [V 2x , V 2y to calculate the translation and rotation parameters p2, m2 of the transformed coordinate system. Then transform [C 3x , C 3y using the translation and rotation parameters calculated twice. Subtract the x and y coordinates of the two transformation results from the x and y of [V 3x , V 3y respectively and take the absolute value. Take the translation and rotation parameters and the input order of the backlight projection image coordinates of the time with the smaller absolute value as the translation and rotation parameters and the input order of the coordinate points during transformation.

[0054] Step S3: Calibrate the transformation parameters between the structured light vision three-dimensional coordinate system and the motion platform coordinate system. Use the backlight projection model and the binocular vision three-dimensional projection model to calibrate the distance from the centers of the three lithographic transparent standard circles of the probe to the center of the probe ball: Place a smooth ring gauge on the transparent platform, detect the working surface circle contour of the ring gauge through backlight projection, and calculate the center XY coordinates [C1_X, C1_Y] of the circle contour and the series of XY coordinates [X i , Y i of the scanning trajectory along the circle contour. Transform the series of XY coordinates of the scanning trajectory to the motion platform coordinates. The three-axis motion platform drives the probe ball to contact both the working surface of the ring gauge and the transparent platform simultaneously and move along the series [X i , Y iCoordinate scanning: The binocular vision system simultaneously tracks three lithography transparent standard circles above the probe, calculates a series of three-dimensional center coordinates of these standard circles, fits these series of three-dimensional center coordinates into three circles, and obtains the three-dimensional center coordinates of these three circles: [C2_X, C2_Y, C2_Z], [C3_X, C3_Y, C3_Z], [C4_X, C4_Y, C4_Z]. Since the probe ball contacts the working surface of the ring gauge and the transparent platform simultaneously during scanning, the Z coordinate of the center XY coordinates [C1_X, C1_Y] calculated from the circle contour is the radius R of the probe ball. Thus, the three-dimensional coordinates of the probe ball center corresponding to [C2_X, C2_Y, C2_Z], [C3_X, C3_Y, C3_Z], [C4_X, C4_Y, C4_Z] are [C1_X, C1_Y, R]. According to the distance formula between points in three-dimensional space, equations can be listed to find the distances d1, d2, d3 from [C2_X, C2_Y, C2_Z], [C3_X, C3_Y, C3_Z], [C4_X, C4_Y, C4_Z] to [C1_X, C1_Y, R], which are the distances from the centers of the three lithography transparent standard circles to the probe ball center.

[0055] Step S4: Binocular vision scanning measurement method: While scanning, the binocular vision tracks three lithography transparent standard circles above the probe and calculates a series of three-dimensional center coordinates of these standard circles. Since the distances from the center coordinates to the probe ball center have been obtained through calibration, according to the distance formula between points in three-dimensional space, the three-dimensional coordinates of the probe ball center corresponding to the center coordinates of the three lithography transparent standard circles can be calculated. Then, based on the probe ball radius, the actual measurement parameters can be calculated. If the actual scanning trajectory coordinates of the part are to be obtained, according to the type of the scanning trajectory, the series of three-dimensional coordinates of the calculated probe ball centers are fitted into contours such as lines, circles, ellipses, or curves corresponding to the type of the scanning trajectory. Since the fitted contour is parallel to the actual contour of the part and the distance is equal to the probe ball radius, the actual contour of the part can be obtained.

[0056] Step S5: Measuring process of the part: The movable fixture picks up the part to the transparent platform, and selects one or more of backlight projection, binocular vision, and structured light scanning according to the characteristics of the part and dimensions, accuracy requirements, etc. for combined measurement. After the measurement is completed, the movable fixture rises, rotates 180 degrees, and then descends to the transparent platform for measurement on the other side. After both sides are measured, classification is performed according to the detection results, and the movable fixture places the detected parts to the specified positions. When using binocular vision scanning measurement, if there is a CAD drawing, the scanning path can be preset, and the CAD drawing is matched with the actual contour of the part obtained by backlight projection or structured light scanning to obtain the transformation relationship matrix between the coordinates of the CAD drawing and the coordinate system of backlight projection or structured light scanning. The scanning path coordinates are converted to the coordinate system of backlight projection or structured light scanning by this matrix, and then converted to the coordinate system of the moving platform according to the coordinate system transformation matrix between the coordinate system of backlight projection or structured light scanning and the coordinate system of the moving platform for scanning. If there is no CAD drawing, the path to be scanned can be detected first by backlight projection or structured light scanning and then binocular vision scanning measurement is performed..

[0057] In the second embodiment of the present invention, referring to Figure 8 , only one lithography transparent standard circle can be used. When calibrating the distance from the center of the lithography transparent standard circle to the center of the measuring ball, the same as the above step S3, only the coordinates of the center of one lithography transparent standard circle detected by binocular vision scanning and the coordinates of the center of the optical surface ring gauge obtained by backlight projection are needed to obtain the distance d1 from the center of the lithography transparent standard circle to the center of the measuring ball. The difference is that when using binocular vision scanning detection, the plane pose of the lithography transparent standard circle needs to be obtained through the deformation of the contour of the lithography transparent standard circle, and then a line segment starting from the coordinates of the center of the lithography transparent standard circle, perpendicular to the plane of the lithography transparent standard circle, and with a distance equal to d1 is calculated to obtain the corresponding scanning coordinates of the center of the measuring ball. The second embodiment can simplify the probe structure and calibration method, but since the accuracy of detecting the plane pose of the lithography transparent standard circle by binocular vision is relatively low, the calibration accuracy and measurement accuracy of the second embodiment will also be reduced accordingly.

[0058] In the third embodiment of the present invention, the lithography transparent standard circle can also be replaced with a standard ball. The advantage is that the standard ball is a standard circle in any direction photographed by the camera, but the processing difficulty and cost of the standard ball are one order of magnitude higher than those of the lithography transparent standard circle. Especially, the lighting scheme is complex. If the luminous effect of the lithography transparent standard circle in the first embodiment is to be achieved, the processing technology is particularly complex. A standard polygon can also be used to achieve the same function as in the first embodiment by detecting the corner points or the center point of the polygon.

[0059] The present invention is not limited to the above-mentioned optimal embodiments, and anyone can derive various other forms of machine vision and scanning detection devices and their working methods under the inspiration of the present invention. All equivalent changes and modifications made in accordance with the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims

1. A machine vision and scanning detection device, characterized in that: It includes a detection table, which is provided with a perspective hole penetrating up and down. A backlight source is erected directly below the detection table opposite to the perspective hole. A transparent platform is fixedly arranged on the upper surface of the detection table directly above the perspective hole. A second camera is erected directly above the transparent platform. A first camera is erected on one side of the second camera at a certain angle with the second camera and aligned with the transparent platform. A structured light scanning mechanism is erected on the other side of the second camera at a certain angle with the second camera and aligned with the transparent platform. A movable fixture is arranged on the front side of the detection table, and the movable fixture extends to the transparent platform for limiting. A three-axis motion platform is installed on the rear side of the detection table, and a probe is fixedly arranged on the Z-axis of the three-axis motion platform; The probe includes a housing, the outer wall of the housing is fixedly connected to the Z-axis. An outer tubular permanent magnet is embedded near the lower end of the inner wall of the housing. A lower annular permanent magnet is embedded above the outer tubular permanent magnet on the inner wall of the housing. An upper annular permanent magnet is embedded above the lower annular permanent magnet on the inner wall of the housing. A measuring rod penetrates through the center of the inner wall of the housing. A measuring ball is arranged at the lower end of the measuring rod. The top of the measuring rod extends out of the housing and is provided with a light source support plate. Three planar light sources are evenly distributed circumferentially along the light source support plate. A lithographic transparent standard circle is installed on each of the planar light sources. A suspended annular permanent magnet is installed on the measuring rod below the support plate. The suspended annular permanent magnet is located between the upper annular permanent magnet and the lower annular permanent magnet. An inner tubular permanent magnet is sleeved on the measuring rod in the outer tubular permanent magnet, and the inner tubular permanent magnet is fixedly connected to the measuring rod; The polarities of the outer tubular permanent magnet and the inner tubular permanent magnet at the adjacent positions are the same. The polarities of the suspended annular permanent magnet and the upper and lower annular permanent magnets at the adjacent positions are the same; A waveform spring fixing ring is fixedly arranged on the inner wall of the housing between the upper and lower annular permanent magnets. A waveform spring is installed in the waveform spring fixing ring. Two passive contact rings are arranged at intervals on the waveform spring. An active contact ring is fixedly arranged circumferentially on the suspended annular permanent magnet. The housing horizontally penetrates from the outer wall to the inner wall in pairs to set an upper safety contact plate, an upper safety contact point and a lower safety contact plate, a lower safety contact point. The upper safety contact plate and the upper safety contact point are parallel to each other and are located above the suspended annular permanent magnet. The lower safety contact plate and the lower safety contact point are parallel to each other and are located below the suspended annular permanent magnet; The upper safety contact point bends upward into an arc-shaped convex shape directly above the active contact ring to form a contact point matching the upper safety contact plate. The lower safety contact point bends downward into an arc-shaped convex shape directly below the active contact ring to form a contact point matching the lower safety contact plate.

2. The machine vision and scanning detection device according to claim 1, characterized in that: The movable fixture includes a rotating table. A jaw cylinder is installed on the rotating table. Concave-shaped supports vertically arranged are respectively fixed on the two jaws of the jaw cylinder. A slide rail is vertically arranged on the concave-shaped support. A slider that is slidably matched with the slide rail and can elastically lift is arranged on the slide rail. A clamping arm is arranged at the rear end of the slider. Both clamping arms extend horizontally backward. A plurality of annular springs are symmetrically arranged on the inner sides of the rear ends of the two clamping arms.

3. The machine vision and scanning detection device according to claim 2, characterized in that: Vertical springs are respectively fixed to the upper and lower parts inside the concave-shaped support, and the other ends of the vertical springs are respectively fixedly connected to the end faces on the corresponding sides of the slider; a fixed block is connected to the rear end of the slider, a slot for the front end of the clamping arm to be inserted is provided at the rear side of the fixed block, and a locking bolt for locking the clamping arm is provided on the fixed block; four annular springs are provided, and are arranged at intervals of two on the inner side wall of the rear end of the clamping arm.

4. A machine vision and scanning detection device according to claim 1, characterized in that: The structured light scanning mechanism includes a structured light scanning axis, a structured light support is installed on the structured light scanning axis, a structured light is connected to the side of the structured light support through a structured light fixing ring, and the structured light passes through the structured light fixing ring and is fixed.

5. A working method of using any one of the machine vision and scanning detection devices as described in claims 1-4, characterized in that, The following steps are carried out: Step S1: Camera model calibration: Calibrate the second camera lens to establish the parameters of the backlight projection model; calibrate the first camera lens and the second camera lens to establish the parameters of the binocular vision three-dimensional projection model; calibrate the second camera lens and the structured light scanning mechanism to establish the parameters of the structured light vision three-dimensional scanning model; when calibrating, calibrate the three projection model parameters to the same reference coordinate system; Step S2: Calibration of the conversion parameters between the backlight projection image coordinate system and the moving platform coordinate system: Place a standard optical flat ring gauge on the transparent platform, measure the circular contour C1 of the working surface of the standard optical flat ring gauge with the backlight projection measurement unit, manually control the moving platform to scan the circular contour of the ring gauge working surface, and calculate the center coordinates [C1x, C1y] of the C1 circular contour and the center coordinates [V1x, V1y] of the scanning trajectory. Repeat the above steps 2 times, place the optical flat ring gauge at different positions on the transparent platform for detection and scanning respectively, and obtain the center coordinates [C2x, C2y], [C3x, C3y] of the circular contours at the other 2 positions of the optical flat ring gauge and the center coordinates [V2x, V2y], [V3x, V3y] of the scanning trajectory. Use 2 corresponding pairs of four-point coordinates, [C1x, C1y], [C2x, C2y] and [V1x, V1y], [V2x, V2y] to calculate the translation and rotation parameters p1, m1 from the backlight projection image coordinate system to the moving platform coordinate system. In order to judge whether it is a left-handed coordinate system or a right-handed coordinate system, then calculate the translation and rotation parameters p2, m2 of the conversion coordinate system with the input order of [C2x, C2y], [C1x, C1y] and [V1x, V1y], [V2x, V2y]. Then convert [C3x, C3y] with the translation and rotation parameters calculated twice, subtract the x and y coordinates of the two conversion results from the x and y coordinates of [V3x, V3y] respectively and take the absolute value, and take the translation and rotation parameters and the input order of the backlight projection image coordinates of the time with the smaller absolute value as the translation and rotation parameters and the input order of the coordinate points during conversion; Step S3: Calibrate the conversion parameters between the structured light vision three-dimensional coordinate system and the motion platform coordinate system; Use the backlight projection model and the binocular vision three-dimensional projection model to calibrate the distances from the centers of the three lithographic transparent standard circles of the probe to the center of the probe ball: Place a smooth ring gauge on the transparent platform, detect the working surface circle contour of the ring gauge through backlight projection, calculate the center XY coordinates [C1_X, C1_Y] of the circle contour and the series of XY coordinates [Xi, Yi] of the scanning trajectory along the circle contour from the circle contour, convert the series of XY coordinates of the scanning trajectory to the motion platform coordinates, the three-axis motion platform drives the probe ball to contact the working surface of the ring gauge and the transparent platform simultaneously and scan along the series of [Xi, Yi] coordinates, the binocular vision system simultaneously tracks the three lithographic transparent standard circles above the probe, calculates the series of three-dimensional center coordinates of these standard circles, fits these series of three-dimensional center coordinates into three circles, and obtains the three-dimensional center coordinates of these three circles: [C2_X, C2_Y, C2_Z], [C3_X, C3_Y, C3_Z], [C4_X, C4_Y, C4_Z]. Since the probe ball contacts the working surface of the ring gauge and the transparent platform simultaneously during scanning, the Z coordinate of the center XY coordinates [C1_X, C1_Y] calculated from the circle contour is the radius R of the probe ball. Thus, the three-dimensional coordinates of the probe ball center corresponding to [C2_X, C2_Y, C2_Z], [C3_X, C3_Y, C3_Z], [C4_X, C4_Y, C4_Z] are [C1_X, C1_Y, R]. According to the distance formula between points in three-dimensional space, equations can be listed to find the distances d1, d2, d3 from [C2_X, C2_Y, C2_Z], [C3_X, C3_Y, C3_Z], [C4_X, C4_Y, C4_Z] to [C1_X, C1_Y, R], which are the distances from the centers of the three lithographic transparent standard circles to the center of the probe ball; Step S4: Binocular vision scanning measurement method: During scanning, the binocular vision tracks the three lithographic transparent standard circles above the probe and calculates the series of three-dimensional center coordinates of these standard circles. Since the distances from the center coordinates to the center of the probe ball have been obtained through calibration, according to the distance formula between points in three-dimensional space, the three-dimensional coordinates of the probe ball center corresponding to the three-dimensional center coordinates of the lithographic transparent standard circles can be calculated, and then the actual measurement parameters can be calculated based on the radius of the probe ball; If the actual scanning trajectory coordinates of the part are to be obtained, according to the type of the scanning trajectory, the series of three-dimensional coordinates of the calculated probe ball center are fitted into a straight line, circle, ellipse, or curve contour corresponding to the type of the scanning trajectory. Since the fitted contour is parallel to the actual contour of the part and the distance is equal to the radius of the probe ball, the actual contour of the part can be obtained; Step S5: Measuring parts process: The movable fixture picks up the parts to the transparent platform, and selects one or more of backlight projection, binocular vision, and structured light scanning according to the characteristics and precision requirements of the parts and dimensions for combined measurement; after the measurement is completed, the movable fixture rises, rotates 180 degrees, and then descends to the transparent platform for measurement on the other side. After both sides are measured, classification is performed according to the detection results, and the movable fixture places the detected parts in the designated positions; when using binocular vision scanning measurement, if there is a CAD drawing, the scanning path is preset in advance, and the CAD drawing is matched with the actual contour of the parts obtained by backlight projection or structured light scanning to obtain the transformation relationship matrix between the coordinates of the CAD drawing and the coordinate system of backlight projection or structured light scanning. The scanning path coordinates are transformed into the coordinate system of backlight projection or structured light scanning by this matrix, and then transformed into the coordinate system of the moving platform according to the coordinate system transformation matrix between the backlight projection or structured light scanning coordinate system and the moving platform coordinate system for scanning; if there is no CAD drawing, the path to be scanned is first detected by backlight projection or structured light scanning and then binocular vision scanning measurement is performed.

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