Binocular vision indirect measurement online compensation method and system for cutting and grinding precision casting

Abstract

The invention discloses a binocular vision indirect measurement online compensation method and system for cutting and grinding a precision casting, and the method comprises the steps: S1, selecting the same reference surfaces of a standard part and a blank part and the machining surface of the standard part, and marking the reference surfaces and the machining surface; s2, images of the standard part and the blank part are collected, feature points of all planes are extracted, and feature point division is carried out; s3, left and right eye feature point matching is carried out based on the feature points of the divided reference surface and the machined surface, the feature point position information of each surface is calculated, and the reference surface and the machined surface of the standard part and the reference surface of the blank part are generated; s4, matching the corresponding reference surfaces of the blank piece and the standard piece, and calculating the plane information of the processing surface of the blank piece in combination with the processing surface of the standard piece; s5, adjusting the posture of the cutter according to the plane information of the machining surface of the blank to realize compensation; according to the method, indirect measurement of the machining surface of the cutting and grinding precision casting and online compensation of the cutter are realized, and the number of the extracted feature points, the calculation precision and the calculation speed are improved.

Description

Technical Field

[0001] The present invention relates to the field of intelligent manufacturing technology, and more particularly to a binocular vision indirect measurement online compensation method and system for cutting and grinding precision castings. Background Art

[0002] In the foundry industry, post-processing technology is a crucial link in the entire production process. However, these processes usually have problems such as high labor intensity, high energy consumption, serious environmental pollution and many safety hazards. In addition, manual operation is inefficient and product consistency is difficult to ensure.

[0003] Therefore, there are many automated processing equipment for such high-rigidity castings.

[0004] However, when cutting and grinding high-rigidity castings, due to assembly errors and the pressure, vibration and other influencing factors caused by the cutting and grinding process, the workpiece displacement often leads to low processing accuracy or even tool collision, which affects production efficiency and production safety. Therefore, during the processing, real-time monitoring of the workpiece position status and real-time adjustment of the tool posture for compensation are related to the processing accuracy and production safety.

[0005] However, most of the compensation methods currently used by existing high-rigidity cutting and grinding equipment are laser offline compensation, and laser measurement compensation usually has problems such as the measurement angle being restricted by the installation relationship and only one point can be measured at a time; and during the cutting and grinding process, due to the influence of the cutting and grinding tools, the cutting surface cannot be directly measured.

[0006] Therefore, how to achieve indirect measurement of the machined surface of precision castings and online compensation of the tool, and improve the number of extracted feature points, calculation accuracy and calculation speed, is an urgent problem that technical personnel in this field need to solve. Summary of the invention

[0007] In view of this, the present invention provides a binocular vision indirect measurement online compensation method and system for cutting and grinding precision castings to solve some of the technical problems mentioned in the background technology.

[0008] In order to achieve the above object, the present invention adopts the following technical solution:

[0009] A binocular vision indirect measurement online compensation method for cutting and grinding precision castings comprises the following steps:

[0010] S1. Select the same reference surface of the standard part and the blank part and the processing surface of the standard part, and mark the reference surface and the processing surface;

[0011] S2. Capture and collect images of standard parts and blanks, extract feature points of each plane based on the markings of the reference surface and the processing surface, and divide the feature points of the reference surface and the processing surface;

[0012] S3. Match the left and right feature points based on the divided reference surface and processing surface feature points, and calculate the position information of the feature points on each surface to generate the reference surface and processing surface of the standard part and the reference surface of the blank;

[0013] S4. Match the corresponding reference surface of the blank and the standard part, and calculate the plane information of the machining surface of the blank in combination with the machining surface of the standard part;

[0014] S5. According to the plane information of the machining surface of the blank, the tool posture of the cutting and grinding surface is adjusted to achieve compensation.

[0015] Preferably, step S1 further includes calibrating the binocular camera, and performing hand-eye calibration on the binocular camera and the cutting and grinding tool.

[0016] Preferably, three or more non-parallel planes or regular curved surfaces are selected as reference surfaces, and the reference surfaces of the blank are selected from several reference surfaces that are the same as the standard parts, and different types of points are pasted on different planes as marks.

[0017] In this embodiment, different types of points are pasted on different planes, including but not limited to color recognition division, visual label division, etc.; correspondingly, when extracting feature points, different extraction methods are selected according to the selected point type.

[0018] Preferably, the specific contents of step S3 include:

[0019] The feature points of the left and right eyes are matched one by one, and the parallax between the feature points of the left and right eyes is calculated. The depth of the feature points is calculated according to the parallax, baseline, and camera focal length, and the three-dimensional position information of each feature point is calculated. According to the obtained three-dimensional position information of the feature points on each surface and the plane to which they belong, the reference surface and processing surface of the standard part and the reference surface of the blank are generated.

[0020] Preferably, the parallax d between the imaging points of the feature point P in the left camera and the right camera is:

[0021] d=|x L -x R |

[0022] Feature point P is at two imaging points P in the left and right cameras L and P R The distance between them is:

[0023] P L -P R =b-(xL -x R )

[0024] Based on the principle of similar triangles:

[0025]

[0026] Then the distance Z from the feature point P to the projection center plane is the depth of the feature point:

[0027]

[0028] According to the principle of similar triangles, the three-dimensional position information X, Y, and Z of the feature point P are obtained:

[0029]

[0030]

[0031] Where b is the baseline, f is the focal length of the camera, and the leftmost side of each imaging plane is taken as the benchmark. L is the x coordinate of point P on the left imaging plane, xR is the x coordinate of point P on the right imaging plane.

[0032] Preferably, the specific content of step S4 is:

[0033] Based on the three-dimensional position information of the feature points on any plane, the plane equation is obtained. The relative position relationship between the reference surface and the processing surface of the standard part is calculated according to the plane equation. The blank part is matched with the corresponding reference surface of the standard part, and the deviation between each reference surface of the blank part and the reference surface of the standard part is calculated. The obtained deviation is added to the processing surface of the standard part, thereby obtaining the plane information of the processing surface of the blank part.

[0034] A binocular vision indirect measurement online compensation system for cutting and grinding precision castings, based on the binocular vision indirect measurement online compensation method for cutting and grinding precision castings, comprises: a binocular camera, an industrial computer, an X-direction servo motor, a Y-direction servo motor, a Z-direction servo motor, a high-speed spindle, and a cutting tool;

[0035] The binocular camera is connected to the industrial computer, which is connected to the X-direction servo motor, the Y-direction servo motor, the Z-direction servo motor and the high-speed spindle through the bus, and a cutting tool is installed at the end of the high-speed spindle;

[0036] Binocular camera, used to capture images of standard parts and blanks;

[0037] The industrial computer is used to process the images of the standard parts and the blank parts collected by the binocular camera, extract the feature points of each plane based on the marks of the reference surface and the processing surface, and divide the feature points of the reference surface and the processing surface; match the left-eye and right-eye feature points based on the divided feature points of the reference surface and the processing surface, and calculate the position information of the feature points on each surface to generate the reference surface and the processing surface of the standard part and the reference surface of the blank part; match the blank part with the corresponding reference surface of the standard part, and infer the plane information of the processing surface of the blank part in combination with the processing surface of the standard part;

[0038] The industrial computer is also used to control the servo motors in the three directions of X, Y, and Z as well as the high-speed spindle movement according to the calculated plane information of the machining surface of the blank to adjust the tool posture of the cutting and polishing surface in real time to achieve compensation.

[0039] Preferably, the binocular vision indirect measurement online compensation system for cutting and grinding precision castings further includes servo motor drivers in the three directions of X, Y, and Z and a high-speed spindle servo driver;

[0040] The bus of the industrial computer is respectively connected to the servo motor drivers and the high-speed spindle servo driver in the three directions of X, Y, and Z. The driver is connected to the servo motor and the high-speed spindle through the motor cable and the encoder cable.

[0041] Preferably, the binocular vision indirect measurement online compensation system for cutting and grinding precision castings also includes a power supply for supplying power to various devices in the system.

[0042] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements a binocular vision indirect measurement online compensation method for cutting and grinding precision castings.

[0043] It can be seen from the above technical scheme that, compared with the prior art, the present invention discloses a binocular vision indirect measurement online compensation method and system for cutting and grinding precision castings, which uses a binocular vision camera to measure the workpiece, does not measure the machining surface during machining, but measures the reference surface, and performs tool compensation based on the position of the machining surface calculated based on the reference surface, thereby realizing indirect measurement and online compensation of the machining surface during machining; the binocular camera used in the present invention has a wide field of view, can extract many feature points at a time, and has high calculation accuracy; the present invention uses a reference surface to determine the position of the blank, and calculates the position of the machining surface of the blank by comparing it with the standard part, which greatly reduces the amount of calculation and improves the calculation speed compared with traditional three-dimensional reconstruction and matching. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0045] Figure 1 A schematic diagram of an online compensation method for binocular vision indirect measurement for cutting and grinding precision castings provided by the present invention;

[0046] Figure 2 A schematic diagram of the reference surface and processing surface selected for the standard part provided by the present invention;

[0047] Figure 3 A schematic diagram of a reference surface selected for the blank provided by the present invention;

[0048] Figure 4 A schematic diagram of depth calculation of feature points provided by the present invention;

[0049] Figure 5 A schematic diagram of three-dimensional position information of feature points provided by the present invention;

[0050] Figure 6 A schematic diagram of a binocular vision indirect measurement online compensation system for cutting and grinding precision castings provided by the present invention. DETAILED DESCRIPTION

[0051] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0052] The embodiment of the present invention discloses a binocular vision indirect measurement online compensation method for cutting and grinding precision castings, such as Figure 1 , including the following steps:

[0053] S1. Select the same reference surface of the standard part and the blank part and the processing surface of the standard part, and mark the reference surface and the processing surface;

[0054] S2. Capture and collect images of standard parts and blanks, extract feature points of each plane based on the markings of the reference surface and the processing surface, and divide the feature points of the reference surface and the processing surface;

[0055] S3. Match the left and right feature points based on the divided reference surface and processing surface feature points, and calculate the position information of the feature points on each surface to generate the reference surface and processing surface of the standard part and the reference surface of the blank;

[0056] S4. Match the corresponding reference surface of the blank and the standard part, and calculate the plane information of the machining surface of the blank in combination with the machining surface of the standard part;

[0057] S5. According to the plane information of the machining surface of the blank, the tool posture of the cutting and grinding surface is adjusted to achieve compensation.

[0058] In order to further implement the above technical solution, step S1 also includes calibrating the binocular camera, and performing hand-eye calibration on the binocular camera and the cutting and grinding tool.

[0059] In order to further implement the above technical solution, Figure 2 and Figure 3 , select three or more non-parallel planes or regular curved surfaces as reference surfaces, select several reference surfaces that are the same as the standard parts as the reference surfaces of the blank, and paste different types of points on different planes as marks.

[0060] In order to further implement the above technical solution, the specific contents of step S3 include:

[0061] The feature points of the left and right eyes are matched one by one, and the parallax between the feature points of the left and right eyes is calculated. The depth of the feature points is calculated according to the parallax, baseline, and camera focal length, and the three-dimensional position information of each feature point is calculated. According to the obtained three-dimensional position information of the feature points on each surface and the plane to which they belong, the reference surface and processing surface of the standard part and the reference surface of the blank are generated.

[0062] In order to further implement the above technical solution, Figure 4 , the disparity d between the imaging points of the feature point P in the left and right cameras is:

[0063] d=|x L -x R |

[0064] Feature point P is at two imaging points P in the left and right cameras L and P R The distance between them is:

[0065] P L -P R =b-(x L -x R )

[0066] Based on the principle of similar triangles:

[0067]

[0068] Then the distance Z from the feature point P to the projection center plane is the depth of the feature point:

[0069]

[0070] According to the principle of similar triangles, the three-dimensional position information X, Y, and Z of the feature point P are obtained, such as Figure 5 :

[0071]

[0072]

[0073] Where b is the baseline, f is the focal length of the camera, and x L is the x coordinate of point P on the left imaging plane, x R is the x coordinate of point P on the right imaging plane, O L and O R is the center of the left and right eyes of the binocular vision camera, L is the imaging plane of the camera, P is any point in space, P L and P R are the imaging points of point P on the left and right cameras respectively. The positions of the imaging points (feature points) can be extracted from the captured images. b is the baseline distance, i.e., the center points of the left and right eyes O. L and O R The distance is determined by the camera used.

[0074] In order to further implement the above technical solution, the specific content of step S4 is:

[0075] Based on the three-dimensional position information of the feature points on any plane, the plane equation is obtained, and the relative position relationship between the reference surface and the processing surface of the standard part is calculated according to the plane equation. The blank part is matched with the corresponding reference surface of the standard part, and the deviation between each reference surface of the blank part and the reference surface of the standard part is calculated. The obtained deviation is added to the processing surface of the standard part, thereby obtaining the plane information of the processing surface of the blank part;

[0076] In this embodiment, the coordinates of the feature points on any one of the planes are assumed to be P(x1, y1, z1), P(x2, y2, z2), and P(x3, y3, z3). Taking the point method calculation as an example, the plane equation is:

[0077] A(x-x1)+B(y-y1)+C(z-z1)=0

[0078] in:

[0079]

[0080] In this embodiment, because the cutting and grinding tool and the camera are hand-eye calibrated, compensation can be achieved by simply aligning the tool with the cutting and grinding surface, and real-time photography, calculation and adjustment can be performed during each processing.

[0081] A binocular vision indirect measurement online compensation system for cutting and grinding precision castings is based on a binocular vision indirect measurement online compensation method for cutting and grinding precision castings, such as Figure 6 , including: binocular camera, industrial computer, X-direction servo motor, Y-direction servo motor, Z-direction servo motor, high-speed spindle, cutting tool;

[0082] The binocular camera is connected to the industrial computer, which is connected to the X-direction servo motor, the Y-direction servo motor, the Z-direction servo motor and the high-speed spindle through the bus, and a cutting tool is installed at the end of the high-speed spindle;

[0083] Binocular camera, used to capture images of standard parts and blanks;

[0084] The industrial computer is used to process the images of the standard parts and the blank parts collected by the binocular camera, extract the feature points of each plane based on the marks of the reference surface and the processing surface, and divide the feature points of the reference surface and the processing surface; match the left-eye and right-eye feature points based on the divided feature points of the reference surface and the processing surface, and calculate the position information of the feature points on each surface to generate the reference surface and the processing surface of the standard part and the reference surface of the blank part; match the blank part with the corresponding reference surface of the standard part, and infer the plane information of the processing surface of the blank part in combination with the processing surface of the standard part;

[0085] The industrial computer is also used to control the servo motors in the three directions of X, Y, and Z as well as the high-speed spindle movement according to the calculated plane information of the machining surface of the blank to adjust the tool posture of the cutting and polishing surface in real time to achieve compensation.

[0086] In this embodiment, the moving positions of the three motors X, Y, and Z are determined by the calculated position of the workpiece processing surface. Because the cutting and grinding tool and the camera have been calibrated by hand and eye, compensation can be achieved by simply aligning the tool with the cutting and grinding surface. During each processing process, real-time photography, calculation and adjustment can be performed.

[0087] In order to further implement the above technical solution, a binocular vision indirect measurement online compensation system for cutting and grinding precision castings also includes servo motor drivers in the three directions of X, Y, and Z and a high-speed spindle servo driver;

[0088] The bus of the industrial computer is respectively connected to the servo motor drivers and the high-speed spindle servo driver in the three directions of X, Y, and Z. The driver is connected to the servo motor and the high-speed spindle through the motor cable and the encoder cable.

[0089] In order to further implement the above technical solution, a binocular vision indirect measurement online compensation system for cutting and grinding precision castings also includes a power supply for supplying power to various devices in the system.

[0090] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements a binocular vision indirect measurement online compensation method for cutting and grinding precision castings.

[0091] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0092] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A binocular vision indirect measurement online compensation method for cutting and grinding precision castings, characterized in that: The following steps are involved: S1. Select the same reference surface of the standard part and the blank part and the processing surface of the standard part, and mark the reference surface and the processing surface; S2. Capture and collect images of standard parts and blanks, extract feature points of each plane based on the markings of the reference surface and the processing surface, and divide the feature points of the reference surface and the processing surface; S3. Match the left and right feature points based on the divided reference surface and processing surface feature points, and calculate the position information of the feature points on each surface to generate the reference surface and processing surface of the standard part and the reference surface of the blank; S4. Match the corresponding reference surface of the blank and the standard part, and calculate the plane information of the machining surface of the blank in combination with the machining surface of the standard part; S5. According to the plane information of the machining surface of the blank, the tool posture of the cutting and grinding surface is adjusted to achieve compensation.

2. The binocular vision indirect measurement online compensation method for cutting and grinding precision castings according to claim 1 is characterized in that: Step S1 also includes calibrating the binocular camera and performing hand-eye calibration on the binocular camera and the cutting and grinding tool.

3. The binocular vision indirect measurement online compensation method for cutting and grinding precision castings according to claim 1 is characterized in that: Three or more non-parallel planes or regular curved surfaces are selected as reference surfaces. The reference surfaces of the blank are selected from several reference surfaces that are the same as the standard parts. Different types of points are pasted on different planes as marks.

4. The binocular vision indirect measurement online compensation method for cutting and grinding precision castings according to claim 1 is characterized in that: The specific contents of step S3 include: The feature points of the left and right eyes are matched one by one, and the parallax between the feature points of the left and right eyes is calculated. The depth of the feature points is calculated according to the parallax, baseline, and camera focal length, and the three-dimensional position information of each feature point is calculated. According to the obtained three-dimensional position information of the feature points on each surface and the plane to which they belong, the reference surface and processing surface of the standard part and the reference surface of the blank are generated.

5. The binocular vision indirect measurement online compensation method for cutting and grinding precision castings according to claim 4 is characterized in that: The disparity d between the imaging points of the feature point P in the left and right cameras is: d=|x L -x R | Feature point P is at two imaging points P in the left and right cameras L and P R The distance between them is: P L -P R =b-(x L -x R ) Based on the principle of similar triangles: Then the distance Z from the feature point P to the projection center plane is the depth of the feature point: According to the principle of similar triangles, the three-dimensional position information X, Y, and Z of the feature point P are obtained: Where b is the baseline, f is the focal length of the camera, and x L is the x coordinate of point P on the left imaging plane, x R is the x coordinate of point P on the right imaging plane.

6. The binocular vision indirect measurement online compensation method for cutting and grinding precision castings according to claim 1 is characterized in that: The specific content of step S4 is: Based on the three-dimensional position information of the feature points on any plane, the plane equation is obtained. The relative position relationship between the reference surface and the processing surface of the standard part is calculated according to the plane equation. The blank part is matched with the corresponding reference surface of the standard part, and the deviation between each reference surface of the blank part and the reference surface of the standard part is calculated. The obtained deviation is added to the processing surface of the standard part, thereby obtaining the plane information of the processing surface of the blank part.

7. A binocular vision indirect measurement online compensation system for cutting and grinding precision castings, characterized in that: A binocular vision indirect measurement online compensation method for cutting and grinding precision castings based on any one of claims 1 to 6, comprising: a binocular camera, an industrial computer, an X-direction servo motor, a Y-direction servo motor, a Z-direction servo motor, a high-speed spindle, and a cutting tool; The binocular camera is connected to the industrial computer, which is connected to the X-direction servo motor, the Y-direction servo motor, the Z-direction servo motor and the high-speed spindle through the bus, and a cutting tool is installed at the end of the high-speed spindle; Binocular camera, used to capture images of standard parts and blanks; The industrial computer is used to process the images of the standard parts and the blank parts collected by the binocular camera, extract the feature points of each plane based on the marks of the reference surface and the processing surface, and divide the feature points of the reference surface and the processing surface; match the left-eye and right-eye feature points based on the divided feature points of the reference surface and the processing surface, and calculate the position information of the feature points on each surface to generate the reference surface and the processing surface of the standard part and the reference surface of the blank part; match the blank part with the corresponding reference surface of the standard part, and infer the plane information of the processing surface of the blank part in combination with the processing surface of the standard part; The industrial computer is also used to control the servo motors in the three directions of X, Y, and Z as well as the high-speed spindle movement according to the calculated plane information of the machining surface of the blank to adjust the tool posture of the cutting and polishing surface in real time to achieve compensation.

8. The binocular vision indirect measurement online compensation system for cutting and grinding precision castings according to claim 7, characterized in that: It also includes servo motor drivers for X, Y, and Z directions and a high-speed spindle servo driver; The bus of the industrial computer is respectively connected to the servo motor drivers and the high-speed spindle servo driver in the three directions of X, Y, and Z. The driver is connected to the servo motor and the high-speed spindle through the motor cable and the encoder cable.

9. The binocular vision indirect measurement online compensation system for cutting and grinding precision castings according to claim 7, characterized in that: It also includes a power supply for supplying power to various devices in the system.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the binocular vision indirect measurement online compensation method for cutting and grinding precision castings described in any one of claims 1 to 6 is implemented.

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