A parameter calibration method and device for image acquisition robot

Abstract

The embodiment of the present invention discloses a parameter calibration method for an image acquisition robot, comprising the following steps: setting an image calibration plate on a robot motion platform in coordination with the viewing angle of an image acquisition device of the robot; presetting one or more walking sequences for the robot, and performing walking sequence movements on the robot motion platform so that the robot acquires image information on the image calibration plate; calculating parameters of the image acquisition device according to the image information and motion information of the walking sequence, and verifying the calculation result, wherein the parameter calibration device comprises a robot motion platform and an image calibration device, which are respectively used to provide a plane for stable motion for the robot and to provide image information for the robot, and the image surface of the image calibration device faces the robot motion platform so that the robot acquires image information; the scheme eliminates the additional requirement for the mechanical accuracy of the calibration platform, has strong adaptability and robustness, and is easy to copy and expand.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of robot image calibration, and in particular to a parameter calibration method and device for an image acquisition robot. Background Art

[0002] The three-dimensional objects in the objective world are transformed into two-dimensional plane images through sensors (such as cameras), and then the images of the objects are output through image processing. Usually, robots need two types of information to judge the position and shape of objects, namely distance information and light and dark information. Of course, as the visual information of objects, there is also color information, but it is not as important as the first two types of information for the position and shape recognition of objects. The robot vision system is highly dependent on light and often requires good lighting conditions to make the image formed by the object clearest, enhance the detection information, and overcome problems such as shadows, low contrast, and mirror reflections.

[0003] The robot calibrates its image acquisition device for the following purposes:

[0004] 1. Correct the mechanical parameters of the robot to obtain an accurate conversion relationship from the readings of the robot's internal sensors, motors, etc. to the robot's position;

[0005] 2. Calculate the parameters of the image acquisition device to obtain the accurate conversion relationship between the world coordinates of the point in the environment and the image coordinates of the corresponding point in the collected image.

[0006] On the one hand, robot calibration is to obtain the high-precision position of the robot to assist in robot movement and path planning; on the other hand, it is to use image acquisition devices to collect images in real time, perceive the robot's surroundings, and assist in the robot's perception and real-time positioning.

[0007] However, the existing robot calibration work generally involves collecting chessboard images multiple times and analyzing the images to correct the robot's transmission and acquisition parameters. However, the calibration work still has the following defects during implementation:

[0008] (1) There are many parameters that need to be calibrated, the calibration process is complicated, and the data that needs to be collected is complex. Current technology makes it difficult to achieve one-time, efficient calibration;

[0009] (2) The flatness of the chessboard surface cannot be guaranteed, which affects the accuracy of image acquisition and reduces the accuracy of parameter calibration. Summary of the invention

[0010] To this end, an embodiment of the present invention provides a parameter calibration method and device for an image acquisition robot, which solves the problems in the prior art by fixing the upper and lower ends of a demonstration drawing and flattening the surface of the drawing while fixing the upper end of the demonstration drawing, and using an automated parameter calibration and module function inspection device to perform robot calibration.

[0011] In order to achieve the above object, the present invention provides the following technical solution on one hand: a parameter calibration method of an image acquisition robot, comprising the following steps:

[0012] Step 100: Setting an image calibration plate on the robot motion platform in accordance with the viewing angle of the robot's image acquisition device;

[0013] Step 200: presetting one or more walking sequences for the robot, and performing actions according to the walking sequences on the robot motion platform, and the robot collects image information on the image calibration plate;

[0014] Step 300: Calculate the parameters of the image acquisition device according to the image information and the motion information of the walking sequence, and verify the calculation results.

[0015] Furthermore, the image calibration plate includes an acrylic plate and a coding checkerboard, the coding checkerboard is fixed on the surface of the acrylic plate, and the image surface of the coding checkerboard faces the robot motion platform.

[0016] Furthermore, the image calibration plate includes an internal reference calibration plate arranged on the robot motion platform for calibrating the optical internal reference of the image acquisition device, and an external reference calibration plate for calibrating the optical external reference of the image acquisition device. The robot completes the image acquisition of the internal reference calibration plate and the external reference calibration plate in sequence according to the walking sequence.

[0017] Further, the walking sequence includes an internal reference walking sequence for collecting internal reference image information on the internal reference calibration board, and an external reference walking sequence for collecting external reference image information on the external reference calibration board;

[0018] The robot collects the internal reference image information according to the internal reference walking sequence. When the robot collects a preset amount of internal reference image information, it collects the external reference image information according to the external reference walking sequence and calculates the internal reference result.

[0019] When the robot collects a preset amount of external reference image information, it stops working and calculates the external reference results.

[0020] Another aspect of the present invention provides the following technical solution: a parameter calibration device for an image acquisition robot, comprising:

[0021] Robot motion platform, used to provide a plane for the robot to move smoothly;

[0022] An image calibration device is arranged on the robot motion platform, the image calibration device provides image information for the robot, and the image surface of the image calibration device faces the robot motion platform so that the robot can collect image information.

[0023] Furthermore, the image calibration device includes an external reference calibration plate and an internal reference calibration plate, and image information is provided by setting a coded checkerboard on both the external reference calibration plate and the internal reference calibration plate. The external reference calibration plate is tilted on the robot motion platform, and the internal reference calibration plate is tilted on the side of the robot motion platform.

[0024] Furthermore, the external parameter calibration plate is arranged on the robot motion platform through a three-dimensional bracket; the three-dimensional bracket includes four telescopic rods arranged on the robot motion platform, and each of the telescopic rods is fixedly connected to a corner of the external parameter calibration plate.

[0025] Furthermore, the internal reference calibration plate is clamped on the side of the robot motion platform by a universal support arm, and the internal reference calibration plate is located on the inner side of the robot motion platform.

[0026] Furthermore, slot plates for guiding the shifting of the chessboard drawing are installed on the two side edges of the internal reference calibration plate, and the lower ends of the two slot plates are provided with strip-shaped blocks, and the lower ends of the strip-shaped blocks are hinged with damping rotation rods, and the outer surface fixed sleeve of the damping rotation rod is provided with a positioning friction block;

[0027] The two side plates of the internal parameter calibration plate are provided with inner concave hole grooves, and a wire-retracting rotating handle is installed in the inner concave hole groove. A retracting coil is wound on the wire-retracting rotating handle. The internal parameter calibration plate is provided with a threading hole, and the pulling wire of the retracting coil is fixed at the upper end angle of the positioning friction block through the threading hole.

[0028] Furthermore, a drawing slot is provided on the inner side of the slot plate, and a through-limiting hole is provided on the outer side of the drawing slot, a flat slide bar is provided between the two through-limiting holes, and two organizing push pieces symmetrically distributed about the central axis of the flat slide bar are provided on the surface of the flat slide bar.

[0029] The embodiments of the present invention have the following advantages:

[0030] (1) The calibration device of the present invention does not require additional precision adjustment steps to ensure accuracy except for the accuracy of each chessboard grid and the flatness of the walking plane. The accuracy of robot calibration is only related to the accuracy of the chessboard grid, the flatness of the walking plane, the walking sequence and the algorithm, eliminating the additional requirement for the mechanical accuracy of the calibration platform;

[0031] (2) The present invention provides a robot automated parameter calibration and module function inspection device with an image acquisition device that is simple in process and easy to use. It has a simple structure, is easy to use, has high production efficiency, and low production cost, and can meet the robot's automated walking and parameter calculation requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0033] The structures, proportions, sizes, etc. illustrated in this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with the technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantial technical significance. Any structural modification, change in proportion or adjustment of size shall still fall within the scope of the technical contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0034] Figure 1 A schematic diagram of a flow chart of a parameter calibration method provided by the present invention;

[0035] Figure 2 A schematic diagram of the overall structure of the calibration device provided by the present invention;

[0036] Figure 3 A schematic diagram of the front view structure of the internal reference calibration plate provided by the present invention;

[0037] Figure 4 A schematic diagram of the side view structure of the internal reference calibration board provided in an embodiment of the present invention;

[0038] In the figure:

[0039] 1-Robot motion platform; 2-Image calibration device; 3-Three-dimensional bracket; 4-Universal support arm; 5-Slot plate; 6-Bar block; 7-Damping rotation rod; 8-Positioning friction block; 9-Inner concave hole groove; 10-Wire retracting rotation handle; 11-Retracting and releasing coil; 12-Threading hole; 13-Drawing threading; 14-Through limit hole; 15-Leveling slide bar; 16-Arrangement push piece; 201-External reference calibration plate; 202-Internal reference calibration plate. DETAILED DESCRIPTION

[0040] The following is a description of the implementation of the present invention by specific embodiments. People familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Obviously, the described embodiments are 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. Example 1

[0041] like Figure 1 As shown, the present invention provides a parameter calibration method for an image acquisition robot. In this embodiment, the robot's internal parameter calibration and external parameter calibration are completed in the same calibration mechanism by combining the robot's appearance characteristics and movement mode to meet the requirements of fully automatic one-time calibration of all parameters.

[0042] The specific steps include:

[0043] Step 100: Setting an image calibration plate on a robot motion platform in accordance with the viewing angle of an image acquisition device of the robot.

[0044] The image calibration board includes an internal reference calibration board for calibrating the optical internal reference of the image acquisition device, and an external reference calibration board for calibrating the optical external reference of the image acquisition device, wherein the internal reference calibration board and the external reference calibration board are both arranged on the robot motion platform.

[0045] Both the internal reference calibration plate and the external reference calibration plate include an acrylic plate and a coding chessboard, wherein the coding chessboard is fixed on the surface of the acrylic plate, and the image surface of the coding chessboard faces the robot motion platform.

[0046] The intrinsic parameters are parameters related to the camera's own characteristics, such as focal length, pixel size, etc., and the extrinsic parameters are parameters of the camera in the world coordinate system, such as device position, rotation direction, etc.

[0047] The image acquisition device of the robot calibrates the internal parameters of the robot by photographing the coded chessboard on the internal reference calibration plate multiple times and distinguishing the images of the coded chessboard. It also calibrates the external parameters of the robot by photographing the coded chessboard on the external reference calibration plate multiple times and distinguishing the images of the coded chessboard.

[0048] Step 200: preset one or more walking sequences for the robot, and the robot moves according to the walking sequences on the robot motion platform, and the robot collects image information on the image calibration plate.

[0049] That is to say, the robot completes the image acquisition of the internal reference calibration plate and the external reference calibration plate in sequence according to the walking sequence.

[0050] Therefore, multiple robots can be calibrated together in the same calibration mechanism, provided that no physical collision occurs when the multiple robots move along their own paths in the calibration device.

[0051] Except for the accuracy of each chessboard square and the flatness of the walking plane, the other parts of the calibration device do not require additional precision adjustment steps to ensure the accuracy. The accuracy of the robot calibration is only related to the accuracy of the chessboard squares, the flatness of the walking plane, the walking sequence and the algorithm, which eliminates the additional requirements for the mechanical accuracy of the calibration platform. It has strong adaptability and robustness and is easy to replicate and expand.

[0052] Step 300: Calculate the parameters of the image acquisition device according to the image information and the motion information of the walking sequence, and verify the calculation results.

[0053] The walking sequence includes an internal reference walking sequence for collecting internal reference image information on the internal reference calibration board, and an external reference walking sequence for collecting external reference image information on the external reference calibration board;

[0054] The robot collects the internal reference image information according to the internal reference walking sequence. When the robot collects a preset amount of internal reference image information, it collects the external reference image information according to the external reference walking sequence and calculates the internal reference result.

[0055] When the robot collects a preset amount of external reference image information, it stops working and calculates the external reference results.

[0056] The entire calibration process, from the beginning to data collection, calculation and verification, is a fully automatic process, without the need for human intervention, thus ensuring mass production efficiency to the greatest extent.

[0057] The global optimization algorithm is built into the robot's software. The algorithm is integrated with the robot's movement to implement communication and synchronously record the mechanical readings during the movement and the images collected by the vision equipment to achieve the effectiveness of calibration data collection.

[0058] The calibration program also verifies the parameters during the calibration process, so that problematic parameters can be discovered and eliminated immediately. Example 2

[0059] like Figure 2 In order to correspond to the above calibration method, the present invention also provides a parameter calibration device for an image acquisition robot, comprising:

[0060] The robot motion platform 1 is used to provide a plane for the robot to move smoothly.

[0061] The image calibration device 2 is arranged on the robot motion platform, and provides image information for the robot. The image surface of the image calibration device faces the robot motion platform so that the robot can collect image information.

[0062] The image calibration device 2 includes an external reference calibration plate 201 and an internal reference calibration plate 202. Image information is provided by setting a coded checkerboard on both the external reference calibration plate 201 and the internal reference calibration plate 202. The external reference calibration plate 201 is tilted on the robot motion platform 1, and the internal reference calibration plate 202 is tilted on the side of the robot motion platform 1.

[0063] The external reference calibration plate 201 is arranged on the robot motion platform 1 through a three-dimensional bracket 3; the three-dimensional bracket 3 includes four telescopic rods arranged on the robot motion platform 1, and each of the telescopic rods is fixedly connected to a corner of the external reference calibration plate 201.

[0064] The angles of the external reference calibration plate 201 and the external reference calibration plate 201 can be adjusted. Therefore, by adjusting the external reference calibration plate 201 or the shooting angle of the external reference calibration plate 201, a large number of experiments can be carried out to verify the accuracy of the internal and external references. The internal reference calibration plate 202 is clamped on the side of the robot motion platform 1 by the universal support arm 4, and the internal reference calibration plate 202 is located on the inner side of the robot motion platform 1.

[0065] There is sufficient coordination between the placement angle of the fixed plate in the calibration device and the field of view direction of the robot's vision module, allowing the robot to successfully capture fixed plate patterns at different angles.

[0066] Due to the differences in the robot's image acquisition device and the robot's assembly process, the robot must undergo a series of movements, and then the parameters of the image acquisition device must be calibrated according to specific reference objects to calculate its differential data. The robot can then calculate the specific positions of the corresponding feature elements in the real-time image based on this set of parameter data, thereby matching the robot's image acquisition device with the robot's own moving device and improving the accuracy of the robot's walking parameters.

[0067] When acquiring an image of a checkerboard drawing, it is important to ensure that the surface of the checkerboard drawing is flat. Therefore, in this embodiment, a structure for smoothing the checkerboard drawing is added to the internal reference calibration plate 202, specifically:

[0068] like Figure 3 and Figure 4As shown, slot plates 5 for guiding the shifting of the chessboard drawing are installed on both side edges of the internal reference calibration plate 202, and the inner side of the slot plates 5 is provided with a drawing through slot 13, and the lower ends of the two slot plates 5 are provided with a strip stopper 6, and the lower ends of the strip stoppers 6 are hinged with a damping rotation rod 7, and the outer surface of the damping rotation rod 7 is fixedly sleeved with a positioning friction block 8.

[0069] The two side plates of the internal reference calibration plate 202 are provided with inner concave hole grooves 9, and a wire-retracting rotating handle 10 is installed in the inner concave hole grooves 9. A retracting coil 11 is wound on the wire-retracting rotating handle 10. The internal reference calibration plate 202 is provided with a threading hole 12, and the pulling wire of the retracting coil 11 is fixed at the upper angle of the positioning friction block 8 through the threading hole 12.

[0070] When placing the chessboard drawing, first insert the chessboard drawing into the drawing slot 13 of the slot plate 5, and move it down along the drawing slot 13 until the lower end of the chessboard drawing touches the strip block 6. At this time, rotate the take-up rotating handle 10 to tighten the take-up and release coil 11, and the positioning friction block 8 rotates around the damping rotating rod 7. The positioning friction block 8 will squeeze the lower end of the chessboard drawing to prevent the chessboard drawing from moving in the slot plate 5 when the universal support arm adjusts its angle, thereby ensuring the positioning effect of the chessboard drawing on the internal reference calibration plate 202.

[0071] When the checkerboard drawing needs to be replaced, it is only necessary to rotate the take-up handle 10 in the opposite direction to loosen the take-up coil 11. The positioning friction block 8 will rotate in the opposite direction around the damping rotation rod 7 due to its own gravity, thereby releasing the squeezing effect of the positioning friction block 8 on the checkerboard drawing, making it convenient to take out and replace the checkerboard drawing.

[0072] The positioning friction block 8 only fixes the lower end of the chessboard drawing. In order to smooth the surface of the chessboard drawing, the slot plate 5 of this embodiment is provided with a through limiting hole 14 on the outside of the drawing slot 13. The upper end of the through limiting hole 14 is bent to coincide with the drawing slot 13. A leveling slide bar 15 is provided between the two through limiting holes 14. Two finishing push pieces 16 symmetrically distributed about the central axis of the leveling slide bar 15 are provided on the surface of the leveling slide bar 15.

[0073] That is to say, after the lower end of the chessboard drawing is fixed by the positioning friction block 8, the leveling slide bar 15 is slightly rotated, and the surface of the chessboard drawing is leveled by the finishing push piece 16 on its surface.

[0074] When the leveling slide bar 15 is bent along the upper end of the limiting hole 14 and coincides with the drawing slit 13, the leveling slide bar 15 can fix the upper end of the checkerboard drawing, and cooperate with the strip stopper 6 at the lower end of the checkerboard drawing to fix the lower end of the checkerboard drawing, thereby fixing the upper and lower ends of the checkerboard drawing, and flattening the surface of the checkerboard drawing, which can ensure that the checkerboard drawing remains flat during calibration and improve the stability and accuracy of image acquisition calibration.

[0075] Although the present invention has been described in detail above by general description and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements can be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all belong to the scope of protection claimed by the present invention.

Claims

1. A parameter calibration method for an image acquisition robot, characterized in that: The steps include: Step 100: Setting an image calibration plate on the robot motion platform in accordance with the viewing angle of the robot's image acquisition device; Step 200: presetting one or more walking sequences for the robot, and performing actions according to the walking sequences on the robot motion platform, and the robot collects image information on the image calibration plate; Step 300: Calculate the parameters of the image acquisition device according to the image information and the motion information of the walking sequence, and verify the calculation results; The image calibration plate comprises an acrylic plate and a coding chessboard, wherein the coding chessboard is fixed on the surface of the acrylic plate, and the image surface of the coding chessboard faces the robot motion platform; The image calibration plate comprises an internal reference calibration plate arranged on the robot motion platform for calibrating the optical internal reference of the image acquisition device, and an external reference calibration plate for calibrating the optical external reference of the image acquisition device, and the robot sequentially completes image acquisition of the internal reference calibration plate and the external reference calibration plate according to the walking sequence; The two side edges of the internal reference calibration plate are equipped with slot plates for guiding the shifting of the chessboard drawing, and the lower ends of the two slot plates are provided with strip-shaped blocks, and the lower ends of the strip-shaped blocks are hinged with damping rotation rods, and the outer surface fixed sleeve of the damping rotation rod is provided with a positioning friction block; The two side plates of the internal reference calibration plate are provided with inner concave hole grooves, and a wire-receiving rotating handle is installed in the inner concave hole groove. A retracting coil is wound on the wire-receiving rotating handle. The internal reference calibration plate is provided with a threading hole, and the pulling wire of the retracting coil is fixed at the upper end angle of the positioning friction block through the threading hole; A drawing slot is provided on the inner side of the slot plate, and a through-limiting hole is provided on the outer side of the slot plate. The upper end of the through-limiting hole is bent to coincide with the drawing slot, and a flat slide bar is provided between the two through-limiting holes. Two finishing push pieces symmetrically distributed about the central axis of the flat slide bar are provided on the surface of the flat slide bar.

2. The parameter calibration method of an image acquisition robot according to claim 1, characterized in that: The walking sequence includes an internal reference walking sequence for collecting internal reference image information on the internal reference calibration board, and an external reference walking sequence for collecting external reference image information on the external reference calibration board; The robot collects the internal reference image information according to the internal reference walking sequence. When the robot collects a preset amount of internal reference image information, it collects the external reference image information according to the external reference walking sequence and calculates the internal reference result. When the robot collects a preset amount of external reference image information, it stops working and calculates the external reference results.

3. A parameter calibration device for an image acquisition robot, characterized in that: include: A robot motion platform (1), used to provide a plane for the robot to move smoothly; An image calibration device (2) is arranged on the robot motion platform, the image calibration device provides image information for the robot, and the image surface of the image calibration device faces the robot motion platform so that the robot can collect image information; The image calibration device (2) comprises an external reference calibration plate (201) and an internal reference calibration plate (202), image information is provided by arranging a coding chessboard on both the external reference calibration plate (201) and the internal reference calibration plate (202), the external reference calibration plate (201) is arranged obliquely on the robot motion platform (1), and the internal reference calibration plate (202) is arranged obliquely on the side of the robot motion platform (1); Slot plates (5) for guiding the shifting of the chessboard drawing are installed at the two side edges of the internal reference calibration plate (202), and the lower ends of the two slot plates (5) are provided with strip-shaped stoppers (6), and the lower ends of the strip-shaped stoppers (6) are hinged with damping rotation rods (7), and the outer surface of the damping rotation rod (7) is fixedly sleeved with a positioning friction block (8); The two side plates of the internal reference calibration plate are provided with inner concave hole grooves (6), a wire reel rotating handle (7) is installed in the inner concave hole groove (6), a reel coil (8) is wound on the wire reel rotating handle (7), and a threading hole (9) is provided on the internal reference calibration plate, and the pulling wire of the reel coil (8) is fixed at the upper end angle of the positioning friction block (8) through the threading hole (9); A drawing slot (10) is provided on the inner side of the slot plate (5), and a through-limiting hole (11) is provided on the outer side of the drawing slot (10). The upper end of the through-limiting hole is bent in a direction that coincides with the drawing slot. A flat slide bar (12) is provided between the two through-limiting holes (11), and two finishing push pieces (13) are provided on the surface of the flat slide bar (12) and are symmetrically distributed about the central axis of the flat slide bar (12).

4. The parameter calibration device for an image acquisition robot according to claim 3, characterized in that: The external reference calibration plate (201) is arranged on the robot motion platform (1) via a three-dimensional bracket (3); the three-dimensional bracket (3) comprises four telescopic rods arranged on the robot motion platform (1), each of the telescopic rods being fixedly connected to a corner of the external reference calibration plate (201).

5. The parameter calibration device for an image acquisition robot according to claim 3, characterized in that: The internal reference calibration plate (202) is clamped on the side of the robot motion platform (1) via a universal support arm (4), and the internal reference calibration plate (202) is located on the inner side of the robot motion platform (1).

Images