Calibration device, calibration apparatus and calibration method for image acquisition unit

Abstract

The present application relates to a kind of image acquisition unit calibration device, calibration equipment and calibration method.Image acquisition unit calibration device includes: track, calibration plate, actuator and multiple trigger units, the calibration plate is connected on the track, multiple trigger units are arranged along the track, the calibration plate can be moved along the track under the drive of the actuator, and can be cooperated with the trigger unit to trigger the image acquisition unit to carry out image acquisition.The present application aims to quickly realize the parameter calibration of image acquisition unit by simple structure and easy-to-implement method.During calibration, no manual intervention is needed, and the calibration process has certain standardization.

Description

Technical Field

[0001] This invention relates to the field of parameter calibration technology for image acquisition devices, and in particular to calibration devices, calibration equipment, and calibration methods for image acquisition units. Background Technology

[0002] Image acquisition devices, such as cameras, require continuous movement of a calibration plate during calibration to acquire multiple images of the calibration plate for calculating the camera's internal and external parameters. Currently, calibration methods are mainly divided into manual, electric, and robot-assisted calibration. Manual calibration primarily involves the experimenter moving the calibration plate within the camera's field of view to acquire multiple images. This method relies heavily on the experimenter's experience, is highly arbitrary, and yields unstable results. Electric calibration mainly uses a motor to move the calibration plate within a two-dimensional plane, during which the camera captures multiple images for calibration. Motorized devices are typically heavy, have complex wiring, are inconvenient to carry, and consume energy. Robot-assisted calibration requires a robotic arm to hold the calibration plate and move it within the camera's field of view, capturing multiple images during the movement. However, robots are too expensive and complex to operate, making them unsuitable for widespread adoption. Summary of the Invention

[0003] Based on this, a calibration device, calibration equipment and calibration method for an image acquisition unit are provided. The structure is simple and easy to implement, and no manual intervention is required during the calibration process, thus standardizing the calibration process.

[0004] A calibration device for an image acquisition unit, characterized in that it comprises: a track; a calibration plate connected to the track and movable along the track; an actuator drivenly connected to the calibration plate; and a plurality of triggering units arranged at intervals along the track, the triggering units being configured to cooperate with the calibration plate to trigger the image acquisition unit to perform image acquisition.

[0005] According to an embodiment of the present invention, multiple triggering units are arranged at intervals on the track to ensure the consistency of the calibration board path and image acquisition in each calibration process, while avoiding the problem of distortion of calibration parameters of the image acquisition unit caused by the experimenter placing the calibration board arbitrarily.

[0006] In one embodiment, the trigger unit has a connection terminal for electrical connection with the image acquisition unit, and the trigger unit is configured to be electrically connected to the calibration board to allow a loop to be formed between the trigger unit, the image acquisition unit, and the calibration board to trigger the image acquisition unit to acquire an image. The electrical connection can simply and effectively trigger the image acquisition unit to acquire an image, is easy to implement, and has good adaptability.

[0007] In one embodiment, the calibration plate has a conductive portion, and the triggering unit includes at least one elastically deformable conductive trigger element to allow the conductive portion to form an electrical connection with the conductive trigger element as it passes through it. When the conductive portion contacts the conductive trigger element as it passes through it, an electrical connection can be formed. This solution provides a simple method for electrical connection.

[0008] In one embodiment, the track has a groove for accommodating the conductive portion, and there are two conductive triggers, each disposed on a opposite surface of the groove. This effectively limits the travel path of the calibration plate.

[0009] In one embodiment, the track includes multiple connected straight track segments, and the multiple triggering units are spaced apart on the multiple straight track segments.

[0010] In one embodiment, multiple straight track segments are arranged parallel to each other, adjacent straight track segments are connected by arc-shaped track segments, and the two arc-shaped track segments located at opposite ends of the straight track segments extend in opposite directions. According to this embodiment, an S-shaped track is provided, which can significantly expand the range of the calibration plate within the field of view of the image acquisition unit.

[0011] In one embodiment, the triggering unit is detachably mounted on the track; and / or, the distance between any two straight track segments can be adjusted.

[0012] In one embodiment, the actuator includes a weight and a traction rope connected between the weight and the calibration plate; wherein the weight is configured to pull the calibration plate along the track by gravity, and the traction rope is configured to allow the calibration plate to pass through all the triggering units during movement. According to this solution, the calibration process relies on non-electric drive, using only the gravitational potential energy of the weight to move the calibration plate in a two-dimensional plane, requiring no human intervention, thus saving both manpower and energy.

[0013] A calibration device for an image acquisition unit includes: a calibration apparatus, wherein the calibration apparatus is the aforementioned calibration apparatus for the image acquisition unit; an image acquisition unit configured to be triggered by a plurality of the triggering units to acquire images; and a parameter calculation unit configured to receive the acquired images and calculate calibration parameters of the image acquisition unit based on the images.

[0014] A calibration method for an image acquisition unit includes the following steps: obtaining a calibration device for the image acquisition unit, wherein the calibration device is the aforementioned calibration device for the image acquisition unit; using the actuator to drive the calibration plate to move along the track and pass through multiple trigger units; cooperating the calibration plate with the trigger units to trigger the image acquisition unit to perform image acquisition; receiving the acquired image; and calculating the calibration parameters of the image acquisition unit based on the acquired image. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of a calibration device for an image acquisition unit according to an embodiment of the present invention;

[0016] Figure 2 This is a schematic diagram of the calibration plate and track assembly according to an embodiment of the present invention;

[0017] Figure 3 for Figure 2 Enlarged view of point A;

[0018] Figure 4 A schematic diagram illustrating the preparation of a conductive portion for electrical connection with a conductive triggering unit according to an embodiment of the present invention.

[0019] Component designation explanation

[0020] 1. Calibration plate; 11. Conductive part; 12. Limiting part; 2. Track; 21. Groove; 22. Flange; 23. Straight track section; 24. Arc track section; 3. Actuator; 31. Weight; 32. Traction rope; 4. Trigger unit; 41. Conductive trigger; 5. Image acquisition unit; 6. Computer; 7. Wire; 8. Support.

[0021] The above description of the main component symbols, together with the accompanying drawings and specific embodiments, provides a more detailed explanation of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the scope of protection of this invention.

[0023] It should be noted that when a component is described as "mounted on" another component, it can be directly on the other component or there may be an intermediate component. When a component is described as "set on" another component, it can be directly set on the other component or there may be an intermediate component. When a component is described as "fixed to" another component, it can be directly fixed to the other component or there may be an intermediate component. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "or / and" as used herein includes any and all combinations of one or more of the associated listed items.

[0025] According to the present invention, a calibration device for an image acquisition unit is provided. The calibration device includes a track, a calibration plate movably mounted on the track, an actuator for driving the calibration plate, and multiple triggering units for cooperating with the calibration plate to trigger the image acquisition unit to acquire images. The actuator is a non-electric device, i.e., mechanically drives the calibration plate to move along the track. The present invention aims to quickly calibrate the parameters of an image acquisition unit through a simple structure and an easy-to-implement method. No manual intervention is required during calibration, and the calibration process is standardized to a certain extent.

[0026] An embodiment of the calibration device for the image acquisition unit according to the present invention is shown in Figure 1 In the middle. For example Figure 1 As shown, the calibration device includes a track 2, multiple trigger units 4 spaced apart on the track 2, a calibration plate 1 that can move along the track 2, and an actuator 3 that drives the calibration plate 1 to move. The calibration device, together with the image acquisition unit and the parameter calculation unit, forms the calibration equipment for the image acquisition unit.

[0027] In the illustrated embodiment, the track 2 is configured in an S-shape and mounted on the bracket 8. The bracket 8 may optionally be height-adjustable. Figure 1As shown, track 2 includes multiple straight track segments 23 spaced apart from each other and arc-shaped track segments 24 connecting adjacent straight track segments 23. To construct an S-shaped track, the two arc-shaped track segments 24 connecting opposite ends of the straight track segments 23 extend in opposite directions. The distance between the straight track segments 23 can be adjusted to better meet calibration parameter requirements. For example, in an embodiment not shown, multiple straight track segments and multiple sets of arc-shaped track segments of different specifications are provided, the difference between the different sets of arc-shaped track segments being that the arc lengths or radii of the track segments they each contain are different. Thus, when adjusting the spacing between the straight track segments, arc-shaped track segments with suitable arc lengths or radii are selected for connection to form an S-shaped track 2. In other embodiments, the spacing between the straight track segments can be uniform or varied as needed.

[0028] Multiple triggering units 4 are arranged at intervals on track 2. (Reference) Figure 1 In the illustrated embodiment, the trigger units 4 are all arranged on straight track segments 23, and the number of trigger units 4 on each straight track segment 23 is the same. They are arranged at uniform intervals along the track 2. Optionally, the S-shaped track 2 includes N (N≥5) straight track segments 23, and N trigger units 4 are arranged on each straight track segment 23, so that the trigger units 4 form an N×N trigger unit array on the entire track 2. In this N×N trigger unit array, the distance between any trigger unit 4 and its lateral and longitudinally adjacent trigger units is the same. The field of view of the image acquisition unit 5 covers the N×N trigger unit array to ensure that the image acquisition unit 5 can acquire all the required images as the calibration plate 1 moves along the track 2.

[0029] In other embodiments, the distance between the triggering units is adjustable. For example, the triggering units are detachably mounted on track 2, thereby adjusting their position as needed.

[0030] Although only the S-shaped track 2 and the triggering units 4 arranged thereon are shown, those skilled in the art will understand that the configuration of the track 2 is not limited to this and can be modified as needed. For example, in an embodiment not shown, straight track segments 23 are connected at an angle to form a polygonal shape, and multiple triggering units 4 are arranged on the straight track segments 23. Arc-shaped track segments can be connected between two adjacent straight track segments 23 as transition sections. Alternatively, the track 2 can be constructed in other shapes that allow the calibration plate 1 to move, while ensuring that the field of view of the image acquisition unit can cover all the triggering units 4 on the track 2, or in other words, cover all the movement positions of the calibration plate 1.

[0031] An embodiment of the triggering unit according to the present invention is shown in Figure 2 and Figure 3 In the middle. For example Figure 2 and Figure 3 As shown, the trigger unit 4 includes two conductive triggers 41 facing each other on opposite sides of the track 2. A gap is formed between the two conductive triggers 41 to allow the calibration plate 1 to pass through. Simultaneously, the two conductive triggers 41 are made of elastic conductive sheet material, such as an elastic metal sheet or a spring sheet, so that when the calibration plate 1 passes through the gap, the conductive triggers 41 can contact at least a portion of the calibration plate 1 to form an electrical connection, without jamming the calibration plate 1 and preventing it from passing through the gap.

[0032] Each trigger unit 4 has a conductive trigger element 41 with a connection end, and the connection ends of the two opposing conductive trigger elements 41 are respectively connected to the positive and negative poles of the external trigger end of the image acquisition unit 5 through wires 7, thereby forming an electrical connection between the trigger unit 4 and the image acquisition unit 5.

[0033] Although the two opposing conductive triggers 41 in each trigger unit 4 of this embodiment are both elastic conductive sheets, those skilled in the art should understand that only one conductive trigger 41 may be an elastic conductive sheet, and it can still form an electrical connection with the calibration plate 1 while allowing the calibration plate 1 to pass through the gap through deformation. Furthermore, the configuration of the conductive trigger 41 can have various variations, as long as at least one of the conductive triggers 41 can produce a recoverable deformation. For example, in an embodiment not shown, two elastically expandable conductive triggers are provided on opposite sides of the track 2, which can form an electrical connection with a portion of the calibration plate 1 passing through the gap through expansion and contraction. The expandable conductive trigger can be a single piece made of a expandable material, or it can be a combination of a expandable element (e.g., a spring) and a contact element (e.g., a metal contact) for contacting the calibration plate 1.

[0034] An embodiment of the calibration plate according to the invention is shown in Figure 1 In the middle. For example Figure 1 As shown, the calibration plate 1 is square and uses a black and white checkerboard pattern, and its dimensions are between 1 / 3 and 1 / 2 of the field of view of the image acquisition unit 5. In this invention, "field of view" or "field of view range" refers to the range that the image acquisition unit can observe or capture. The larger the field of view, the larger the range of observation or capture; the smaller the field of view, the smaller the range of observation or capture.

[0035] To achieve the movement of calibration plate 1 along track 2, and the electrical connection between calibration plate 1 and trigger unit 4, as follows: Figure 2As shown, the track 2 has a groove 21 extending along its length, and the calibration plate 1 has a conductive part 11, for example cylindrical in shape, on its side facing away from the chessboard. The conductive part 11 extends into the groove 21, can move along the track 2, and its movement path is restricted by the track 2. Simultaneously, when passing a trigger unit 4, the conductive part 11 is sandwiched between two opposing conductive trigger elements 41, thereby forming an electrical connection between the conductive part 11 and the two conductive trigger elements 41. Although Figure 2 The conductive portion 11 is shown in a cylindrical shape, but those skilled in the art will understand that the shape of the conductive portion 11 is not limited to this and can be modified as needed. For example, in an embodiment not shown, the conductive portion 11 is elliptical, spherical, truncated spherical, etc.

[0036] To prevent calibration plate 1 from detaching from track 2, such as Figure 2 As shown, the groove wall of the groove 21 forming the track 2 has two opposing flanges 22 at the groove opening, thus forming a narrowed portion at the groove opening of the groove 21. Correspondingly, a limiting portion 12 is connected to the end of the conductive part 11 of the calibration plate 1. The conductive part 11 is sized to pass through the narrowed portion at the groove opening of the groove 21, while the limiting portion 12 is sized to be accommodated in the groove 21 but not to pass through the narrowed portion at the groove opening of the groove 21, thereby preventing the calibration plate 1 from detaching from the track 2 during movement. Two conductive triggers 41 of each trigger unit 4 are respectively provided on the two flanges 22, so that when the calibration plate 1 passes through each trigger unit 4, the conductive part 11 can contact the two conductive triggers 41 and form an electrical connection.

[0037] An embodiment of the actuator according to the present invention is shown in Figure 1 In the middle. For example Figure 1 As shown, the actuator 3 uses mechanical actuation to drive the calibration plate 1 to move along the track 2. The actuator 3 includes a weight 31 and a traction rope 32 connecting the weight 31 and the calibration plate 1. The weight 31 is configured to pull the calibration plate 1 along the track by gravity, and to ensure that when the calibration plate 1 passes the trigger unit 4, it will not be jammed by the two opposing conductive triggers 41, thus preventing subsequent image acquisition and parameter calibration from being impossible. In one embodiment, the weight 31 is greater than the weight of the calibration plate 1, and is 1.5-5 times the weight of the calibration plate 1, preferably 1.5-2 times. The traction rope 32 is configured to allow the calibration plate 1 to move through all trigger units 4.

[0038] Optionally, the traction rope 32 is made of a soft and non-stretchable material.

[0039] Alternatively, the traction rope 32 may be placed in the groove 21 of the track 2.

[0040] The present invention also provides a calibration device for an image acquisition unit. For example... Figure 1As shown, the calibration device includes the aforementioned calibration apparatus, an image acquisition unit 5 connected to the calibration apparatus, and a parameter calculation unit for the image acquisition unit 5. The image acquisition unit 5 is, for example, a camera. The parameter calculation unit is, for example, a program instruction installed in a computer 6.

[0041] The following is a detailed description of the operation procedure for the calibration device of the image acquisition unit according to this application.

[0042] The calibration method for the image acquisition unit includes the following steps:

[0043] S1: Obtain the calibration device for the image acquisition unit as described above.

[0044] exist Figure 1 In the specific embodiment shown, the track 2 of the calibration device is configured in an S-shape consisting of five straight track segments 23 and four curved track segments 24. Five trigger units 4 are evenly spaced on each straight track segment 23. Each trigger unit 4 includes two conductive trigger elements 41 made of elastic metal sheets. The cylindrical conductive part 11 of the calibration plate 1 passes through the groove 21 of the track 2 and can move along the groove 21 under the drive of the weight 31 and the traction rope 32. As mentioned earlier, the track 2 can be placed on a height-adjustable support 8 (e.g., a tripod), the height of which can be selected to ensure that the weight 31 does not touch the ground at its lowest position.

[0045] S2: The calibration plate is driven to move along the track by the actuator in the calibration device and passes through multiple trigger units.

[0046] exist Figure 1 In the specific implementation shown, the weight 31 is released and allowed to fall. With the help of gravitational potential energy, the calibration plate 1 is pulled along the S-shaped track 2 in a two-dimensional plane by the traction rope 32.

[0047] S3: Enables the calibration board to work with each trigger unit to trigger the image acquisition unit to acquire images.

[0048] exist Figure 1 Combination Figure 4 In the specific embodiment shown, when the calibration plate 1 moves to the position of the trigger unit 4, the conductive part 11 of the calibration plate 1 passes between the two opposing conductive triggers 41. The two conductive triggers 41 undergo elastic deformation, contacting the conductive part 11 to form an electrical connection, while not preventing the conductive part 11 from moving along... Figure 4The direction indicated by the middle arrow passes through the gap between the two conductive triggers 41. Since each of the two conductive triggers 41 is also electrically connected to the positive and negative terminals of the external trigger of the image acquisition unit 5 via wires 7, when the conductive part 11 contacts the two conductive triggers 41, a circuit is formed between the conductive part 11 of the calibration plate 1, the trigger unit 4, and the image acquisition unit 5, triggering the image acquisition unit 5 to acquire an image, for example, triggering a camera to take a picture. During the process of the weight 31 pulling the calibration plate 1 along the track 2, the calibration plate 1 passes through all the trigger units 4, triggering the image acquisition unit 5 to acquire an image once at each trigger unit 4. After traversing all the trigger units 4, the acquisition of all calibration images is completed.

[0049] After image acquisition is completed, the calibration method may further include the following steps:

[0050] S4: Receive the acquired image.

[0051] exist Figure 1 In the specific embodiment shown, this step is implemented, for example, by receiving software such as program instructions installed in the computer 6, or by receiving hardware such as a port. Optionally, after the calibration board 1 has passed the last trigger unit 4 and completed the corresponding image acquisition, this step is implemented by the parameter calculation unit installed in the computer 6.

[0052] S5: Calculate the calibration parameters of the image acquisition unit based on the acquired image.

[0053] exist Figure 1 In the specific embodiment shown, after receiving all the images, the parameter calculation unit calculates the calibration parameters of the image acquisition unit 5 based on these images. In a further embodiment, the parameter calculation unit also stores the calculated calibration parameters. In other embodiments, the parameter calculation unit can upload the obtained calibration parameters to a server or other storage device. The parameter calibration of the image acquisition unit by the parameter calculation unit can be achieved using the Zhang Zhengyou camera calibration method.

[0054] Although the trigger unit 4 and calibration plate 1 are electrically connected to form a circuit to trigger the image acquisition unit 5, as described above, those skilled in the art will understand that the connection method is not limited to forming a circuit and can be adjusted as needed. For example, in an embodiment not shown, the trigger unit 4 is a sensor, such as an infrared sensor. When the calibration plate 1 passes the trigger unit 4, the sensor emits a trigger signal, and the image acquisition unit 5 has a signal collector that receives this trigger signal. Upon receiving the trigger signal, the image acquisition unit 5 starts and performs image acquisition.

[0055] The calibration device and calibration method for the image acquisition unit according to the present invention can achieve the following technical effects:

[0056] 1. The S-shaped track setting ensures that the calibration board follows the same path each time it is calibrated, and at the same time, it can fully expand the range of the calibration board in the field of view of the image acquisition unit, overcoming the problem of distortion of the calibration parameters of the image acquisition unit caused by the arbitrary placement of the calibration board by the experimenter.

[0057] 2. The calibration process relies on the gravitational potential energy of the weight to drive the calibration plate to move in a two-dimensional plane. No human intervention is required, which saves both manpower and energy.

[0058] 3. A trigger unit array is set up, which can provide a standardized process for the calibration of the image acquisition unit, ensuring that the shooting position of the image used for calibration remains consistent, eliminating the randomness caused by the experimenter placing the calibration plate, and making the calibration results repeatable.

[0059] 4. The setting of the elastic metal sheet of the trigger unit fixes the shooting position, which solves the problem of image shooting during the movement of the calibration plate. At the same time, the damping effect of the elastic metal sheet can reduce the moving speed of the calibration plate and improve the clarity of the captured image.

[0060] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0061] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A calibration device for an image acquisition unit, characterized in that Comprising: a track; a calibration plate connected on the track and movable along the track; an actuating member drivingly connected to the calibration plate; a plurality of triggering units arranged at intervals along the track, the triggering units being configured to cooperate with the calibration plate to trigger the image acquisition unit to perform image acquisition when the calibration plate passes the triggering units; the calibration plate having a conductive portion, the triggering units including at least one elastically deformable conductive triggering member to allow the conductive portion to form an electrical connection with the conductive triggering member when passing the conductive triggering member; the actuating member including: a weight; and a traction rope connected between the weight and the calibration plate; wherein the weight is configured to pull the calibration plate to move along the track by gravity, and the traction rope is configured to allow the calibration plate to pass all the triggering units during the movement.

2. The calibration device of claim 1, wherein The track has a groove accommodating the conductive portion, and the conductive triggering member has two conductive triggering members arranged on two opposite surfaces of the groove, respectively.

3. The calibration device according to claim 1 or 2, characterized in that The track includes a plurality of straight track segments connected together, and the plurality of triggering units are arranged at intervals on the plurality of straight track segments.

4. The calibration device of claim 3, wherein The plurality of straight track segments are arranged in parallel with each other, two adjacent straight track segments are connected by an arc-shaped track segment, and two arc-shaped track segments located at opposite ends of the straight track segment extend in opposite directions.

5. The calibration device of claim 3, wherein The triggering units are detachably mounted on the track; and / or, the distance between any two straight track segments can be adjusted.

6. A calibration device for an image acquisition unit, characterized in that Comprising: a calibration device of the image acquisition unit according to any one of claims 1 to 5; an image acquisition unit configured to be triggered by the plurality of triggering units and perform image acquisition; and a parameter calculation unit configured to receive the acquired images and calculate calibration parameters of the image acquisition unit according to the images. Comprising the following steps:

7. A method of calibrating an image acquisition unit, characterized in that obtaining a calibration device of an image acquisition unit, the calibration device being a calibration device of the image acquisition unit according to any one of claims 1 to 5; driving the calibration plate to move along the track by the actuating member and pass the plurality of triggering units; cooperating the calibration plate with the triggering units to trigger the image acquisition unit to perform image acquisition; receiving the acquired images; calculating calibration parameters of the image acquisition unit according to the acquired images. ​

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