Preset position accuracy testing fixture and preset position accuracy testing system

Abstract

This utility model relates to the field of security monitoring technology, and provides a preset position accuracy testing fixture and a preset position accuracy testing system. The mounting component in the testing fixture is suitable for mounting a camera; the guide component in the calibration component is located on the front side of the mounting component and is suitable for extending horizontally; the linear drive component is disposed on the guide component and can move vertically; the grid calibration component is disposed on the linear drive component and can move with the linear drive component to switch between a first position and a second position; the display screen is located on the side of the grid calibration component opposite to the mounting component; in the first position, the grid calibration component obstructs the display screen, and the camera is used to acquire the reference image information of the grid calibration component; in the second position, the grid calibration component unobstructs the display screen, triggering the intelligent operation of the camera. This utility model not only shortens the testing time of a single device but also supports parallel testing of multiple devices, reducing labor and time costs.

Description

Technical Field

[0001] This utility model relates to the field of security monitoring technology, and in particular to a preset position accuracy testing fixture and preset position accuracy testing system. Background Technology

[0002] With the continuous growth in demand for visual monitoring in fields such as security surveillance, intelligent transportation, and industrial IoT, PTZ network cameras (IP cameras, IPCs) have become one of the core devices in scenarios such as public safety and smart cities due to their remote control capabilities, multi-angle adjustment, and intelligent monitoring features. Among them, the preset position setting function, as a core intelligent capability of PTZ IPCs, enables rapid positioning, automatic patrol, and target tracking of key areas by pre-storing PTZ parameters for specific spatial locations, significantly improving monitoring efficiency and flexibility.

[0003] Because the mechanical structure of a PTZ IPC is typically driven by a stepper motor or servo motor, it achieves horizontal and vertical rotation through gear sets, belts, and other transmission components. Limited by the mechanical characteristics of the motor itself and environmental factors, PTZ IPCs are prone to accumulating preset position accuracy errors after repeated rotations. Specifically, when the camera repeatedly calls the same preset position, the deviation between the actual pointing position and the initial set position gradually increases, causing the monitored image to deviate from the target area and severely affecting the effectiveness of monitoring key areas.

[0004] To address the aforementioned issues, existing technologies primarily employ manual inspection to assess preset position accuracy. Specifically, maintenance personnel periodically and manually call up the preset position, using visual observation or simple tools (such as a protractor or ruler) to determine if the image deviates from the target area, and record the error value. However, while this method can detect preset position accuracy, manual inspection results are not accurate enough, and repeated testing is time-consuming and labor-intensive, making it difficult to provide timely warnings before errors affect monitoring. Utility Model Content

[0005] This utility model provides a preset position accuracy testing fixture and a preset position accuracy testing system to solve the above-mentioned technical defects in the prior art. It can not only shorten the testing time of a single device, but also support parallel testing of multiple devices (through multi-channel control), thereby reducing labor and time costs.

[0006] The first aspect of this utility model provides a preset position accuracy testing fixture, comprising:

[0007] Mounting components, suitable for mounting cameras;

[0008] Calibration components, including:

[0009] A guide assembly, located on the front side of the mounting component, is adapted to extend in a horizontal direction;

[0010] A linear drive assembly is disposed on the guide assembly and is adapted to move in the vertical direction;

[0011] A grid calibration component is disposed on the linear drive component and adapted to move with the linear drive component to switch between a first position and a second position;

[0012] The display screen is located on the side of the grid calibration component opposite to the mounting component and is arranged parallel to the grid calibration component;

[0013] In the first position, the grid calibration component obstructs the display screen, and the camera is used to collect the reference image information of the grid calibration component; in the second position, the grid calibration component removes the obstruction of the display screen, triggering the camera's intelligent service operation.

[0014] According to the preset position accuracy testing fixture provided by this utility model, the grid calibration component includes:

[0015] A grid calibration plate, mounted on the linear drive assembly, is used to provide a two-dimensional grid reference system with known physical coordinates. The size of the grid calibration plate covers the horizontal and vertical fields of view of the camera.

[0016] At least one marking section is provided at the grid intersection of the grid calibration plate, and each marking section is used to provide a high-contrast feature reference marking point.

[0017] According to the preset position accuracy testing fixture provided by this utility model, the marking part includes LED beads, which are pasted and fixed to the grid intersections on the grid calibration plate.

[0018] According to the preset position accuracy testing fixture provided by this utility model, the marking part includes at least two LED beads that emit two different colors of light, and each LED bead is pasted and fixed to the grid intersection point on the grid calibration plate;

[0019] In this system, LED beads emitting one color of light serve as the main reference marker, which is located at the geometric center of the image; LED beads emitting another color of light serve as auxiliary reference markers, which are symmetrically distributed around the main reference marker to cover different quadrants of the image.

[0020] According to the preset position accuracy testing fixture provided by this utility model, the two different colors of light include red light and blue light, wherein the red light forms the main reference marker point and the blue light forms the auxiliary reference marker point.

[0021] According to the preset position accuracy testing fixture provided by this utility model, the linear drive assembly includes:

[0022] A support member is disposed on the guide assembly and is adapted to move horizontally along the guide assembly;

[0023] A linear drive module is disposed on the support member and is adapted to move in the vertical direction;

[0024] The grid calibration component is located in the linear drive module and cooperates with the support member for guidance.

[0025] According to the preset position accuracy testing fixture provided by this utility model, the linear drive module includes:

[0026] A driving component is disposed on the support component;

[0027] A lead screw is rotatably mounted on the support member, the lead screw is driven by the output shaft of the drive member, and the lead screw is connected to the grid calibration assembly through a lead screw nut;

[0028] The support member has a receiving cavity and a guide groove along the axial direction. The guide groove communicates with the receiving cavity. The drive member and the lead screw are located in the receiving cavity. The grid calibration component is guided and engaged with the guide groove.

[0029] The preset position accuracy testing fixture provided by this utility model also includes a first limiting component and a second limiting component;

[0030] The first limiting component is located at the bottom of the support member, and the second limiting component is located at the top of the support member.

[0031] According to the preset position accuracy testing fixture provided by this utility model, the guide component includes two guide rails that are spaced apart and arranged opposite to each other, and each guide rail is provided with a scale value;

[0032] Both the linear drive assembly and the display screen are mounted on the guide rail.

[0033] A second aspect of this utility model provides a preset position accuracy testing system, including at least one camera and any of the preset position accuracy testing fixtures described in the present invention, wherein each camera is disposed on a mounting component of the preset position accuracy testing fixture.

[0034] This utility model provides a preset position accuracy testing fixture that uses a guiding component to accurately position the grid calibration component. A linear drive component automatically switches the position of the grid calibration component, switching between a first position and a second position. Combined with synchronous triggering of the display screen, this transforms the cumulative detection of preset position errors in the PTZ camera from manual subjective observation to objective machine measurement. This not only shortens the testing time for a single device but also supports parallel testing of multiple devices (through multi-channel control), reducing labor and time costs. It replaces the inefficient and inaccurate steps of traditional manual testing, reducing labor and time costs during project development while improving the reliability and real-time performance of test results, providing crucial technical support for the long-term reliable operation of the PTZ IPC.

[0035] Furthermore, the preset position accuracy testing system provided by this utility model, because it includes the aforementioned preset position accuracy testing fixture, possesses all the advantages of the aforementioned preset position accuracy testing fixture. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of the structure of the preset position accuracy testing fixture provided in this embodiment of the utility model.

[0038] Figure 2 This is a schematic diagram of the networking environment of the preset position accuracy testing system provided in this embodiment of the utility model.

[0039] Figure 3 These are schematic diagrams of images obtained during the operation of the preset position accuracy testing system provided in this embodiment of the present invention, wherein (a) is a schematic diagram of the reference image and (b) is a schematic diagram of the deviation image.

[0040] Figure 4 This is a schematic diagram of offset angle calculation provided by an embodiment of the present invention.

[0041] Figure label:

[0042] 10. Mounting components; 20. Calibration components; 21. Guiding components; 22. Linear drive components; 221. Support components; 222. Linear drive modules; 23. Grid calibration components; 231. Grid calibration plates; 232. Marking components; 30. Display screen; 40. Camera. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0044] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.

[0045] In the embodiments of this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0046] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the embodiments of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0047] Figure 1 This is a schematic diagram of the structure of the preset position accuracy testing fixture provided in this embodiment of the utility model.

[0048] See Figure 1 This utility model provides a preset position accuracy testing fixture, which includes a mounting component 10, a calibration component 20, and a display screen 30.

[0049] Mounting component 10 is used to mount camera 40, such as a fixed pan-tilt network camera 40 (IPC), to ensure that the position and angle of camera 40 remain unchanged during testing, and to avoid additional errors introduced by mechanical vibration or human movement.

[0050] The mounting component 10 can employ an adjustable three-axis mechanical bracket (X / Y / Z axes) to accommodate different IPC mounting interfaces, such as threaded holes and quick-release clips. The bottom of the bracket is equipped with leveling feet (including a bubble level) to ensure minimal deviation between the mounting plane and the horizontal plane. The top of the bracket features a camera 40 clamping slot to hold IPC bodies of different sizes.

[0051] The calibration component 20 includes a guide assembly 21, a linear drive assembly 22, and a grid calibration assembly 23.

[0052] The guide assembly 21 is located on the front side of the mounting component 10 and is adapted to extend in a horizontal direction. The guide assembly 21 is used to provide precise horizontal motion guidance for the linear drive assembly 22 and the grid calibration assembly 23.

[0053] The guide component 21 can be a double linear guide rail or track. The length of the guide rail or track is designed according to the field of view coverage of the camera 40. For example, a horizontal field of view of 355° corresponds to a guide rail length of 1.2m. The guide rail or track is mounted on the aluminum alloy profile frame on the front side of the mounting component 10.

[0054] The linear drive assembly 22 is mounted on the guide assembly 21 and is adapted to move in the vertical direction. Specifically, a slider that mates with the guide rail can be provided on the linear drive assembly 22. The mating surface between the slider and the guide rail can be a ball bearing to reduce the coefficient of friction and ensure smooth, jam-free movement. Alternatively, a pulley that mates with the track can be provided on the linear drive assembly 22, with the mating surface between the pulley and the track engaging in a rolling contact.

[0055] Mesh calibration component 23 is disposed on linear drive component 22 and is used to provide a two-dimensional mesh reference system with known physical coordinates. Mesh calibration component 23 is adapted to move with linear drive component 22 to switch between a first position and a second position.

[0056] The grid calibration component 23 includes a grid calibration plate 231, which is made of aluminum alloy or acrylic. High-contrast grid lines, such as black lines, can be printed or laser-engraved on the surface of the grid calibration plate 231 to ensure that the position and size of the grid remain stable under different lighting conditions (such as strong light and weak light) and during long-term use. A connecting plate is provided on the grid calibration plate 231. The connecting plate can be made of aluminum alloy and is fixed to the linear drive component 22. Reinforcing ribs are designed on the back to ensure that it does not deform during lifting.

[0057] The size of the grid calibration plate 231 covers the camera's horizontal field of view (e.g., a horizontal 355° corresponds to a grid width of 1.2m) and vertical field of view (e.g., a vertical -10°~90° corresponds to a grid height of 0.8m).

[0058] A marking part 232 is provided on the grid calibration plate 231. The marking part 232 can be a miniature LED bead welded at the grid intersection, such as every 20mm×20mm intersection. The LED bead can be red, and the wavelength of the LED bead is compatible with the infrared filter of the camera 40, so that the wavelength of the light emitted by the LED bead matches the transmission or cutoff characteristics of the infrared filter of the camera, thereby ensuring that the camera can image normally under different lighting conditions.

[0059] The display screen 30 is located on the side of the grid calibration component 23 away from the mounting component 10, i.e., on the lens side of the camera 40, and the display screen 30 is parallel to the grid calibration component 23. In the first position, the grid calibration component 23 obstructs the display screen 30, and the camera 40 is used to acquire reference image information from the grid calibration component 23. In the second position, after the grid calibration component 23 removes its obstruction of the display screen 30, it triggers the intelligent operation of the camera 40, such as human tracking or automatic cruise. After completing the intelligent operation, it returns to the preset position.

[0060] The display screen 30 can be a high-brightness LED display screen, and its size matches that of the grid calibration component 23. The display screen 30 is synchronized with the servo motor controller of the linear drive component 22 via an RS485 interface. When the grid calibration component 23 reaches the second position, the display screen 30 receives a trigger signal (such as a high-level pulse) to trigger the video of the intelligent service.

[0061] The usage process of the preset position accuracy testing fixture provided in this embodiment of the utility model is as follows:

[0062] Phase 1: The grid calibration component 23 is in the first position, performing system initialization and baseline image acquisition.

[0063] First, fix the IPC to the mechanical bracket using the mounting component 10 and adjust the level of the bracket; lower the grid calibration component 23 to the lowest position (i.e., the first position) using the linear drive component 22 to ensure that the grid calibration component 23 completely blocks the display screen 30, at which point the display screen 30 does not display anything.

[0064] Then, the camera 40 is controlled to enter the calibration mode. By adjusting the pan-tilt IPC and the distance L between the pan-tilt IPC and the grid calibration plate 231, the edge of the real-time area of ​​the pan-tilt IPC is aligned with the grid lines on the grid calibration plate 231 to ensure the correspondence between the pixel points and the actual distance, which is used for subsequent calculation of the actual horizontal and vertical offset distances.

[0065] Phase 2: The grid calibration component 23 is located in the second position to perform intelligent business simulation.

[0066] First, the control system (PLC) sends an "up" command to the servo motor, and the linear drive component 22 drives the grid calibration component 23 to rise at a constant speed. When the grid calibration component 23 reaches the second position (unblocking the display screen 30), the display screen 30 receives a trigger signal and displays a video of the flow of people to trigger the intelligent service. The motor in the IPC pan-tilt unit tracks the flow of people and rotates back and forth.

[0067] The third stage is error calculation and analysis.

[0068] Image processing software was used to extract features from the baseline and test image sets, including the feature points of grid intersections and LED beads. False matching points were filtered out using an algorithm, and valid matching points were retained.

[0069] Based on the physical parameters of the grid calibration plate 231 (such as grid spacing D) and the image resolution (such as pixels), the proportionality coefficient k between pixels and actual distance is calculated, where k = D / the pixel width of the grid in the image. For example, if the grid spacing D is 10cm and the grid occupies 200 pixels in the image, then k = 10cm / 200 pixels = 0.05cm / pixel. The pixel displacement is converted into actual horizontal / vertical errors: ΔX = k |Δu |, ΔY = k |Δv |.

[0070] It is understood that the preset position accuracy testing fixture provided in this embodiment of the present invention uses the guide component 21 to accurately position the grid calibration component 23, and automatically switches the position of the grid calibration component 23 through the linear drive component 22, that is, switching between the first position and the second position. Combined with the synchronous triggering of the display screen 30, the preset position error accumulation detection of the PTZ camera 40 is transformed from manual subjective observation to machine objective measurement. This not only shortens the detection time of a single device, but also supports parallel testing of multiple devices (through multi-channel control), reducing labor and time costs. It replaces the inefficient and inaccurate steps of traditional manual inspection, reducing labor and time costs during project development, while improving the reliability and real-time performance of the detection results, providing key technical support for the long-term reliable operation of the PTZ IPC.

[0071] Continue reading Figure 1 In some embodiments of this invention, the grid calibration component 23 includes a grid calibration plate 231 and at least one marking part 232. The grid calibration plate 231 is disposed on the linear drive component 22 and is used to provide a two-dimensional grid reference system with known physical coordinates. The size of the grid calibration plate 231 covers the horizontal and vertical fields of view of the camera 40, ensuring that the target area pointed to by the camera 40 is covered by the grid when any preset position is invoked. At least one marking part 232 is disposed at the grid intersection of the grid calibration plate 231, and each marking part 232 is used to provide a high-contrast feature reference marking point.

[0072] Essentially, the grid calibration plate 231 and the marking unit 232 work together to form the core reference benchmark module of the preset position accuracy test fixture, providing a standardized spatial reference system and highly reliable feature reference marking points for the PTZ network camera 40 (IPC).

[0073] Among them, the grid calibration plate 231 is a digital carrier of the physical space in the tooling. Through a predefined two-dimensional grid coordinate system, the field of view of the camera 40 is mapped into quantifiable mathematical coordinates, providing a basis for subsequent conversion of pixels and physical distance.

[0074] The surface of the grid calibration plate 231 is printed with a regular two-dimensional grid (such as an M×N square, with each square having a side length of n=10mm). Each grid intersection corresponds to a known physical coordinate, such as: (X=0,Y=0), (X=10mm,Y=0), ..., (X=100mm,Y=0mm), etc. The field of view of the camera 40 (such as 355° horizontally and -10°~90° vertically) is transformed into a calculable mathematical grid, so that the deviation of different preset positions (such as a horizontal offset of 5mm and a vertical offset of 3mm) can be directly quantified through the grid coordinates.

[0075] The marking unit 232 is set at the grid intersection (i.e., the coordinate origin or key node of the grid calibration plate 231) and provides easily identifiable feature anchors for the camera 40 through high-contrast physical features (such as LED beads and colored dots).

[0076] During the baseline image acquisition phase, when the grid calibration plate 231 obscures the display screen 30, the camera 40 captures an image containing the marker 232. Because the marker 232 (such as a red LED bead) forms a high contrast with the grid background (black lines), the image processing algorithm can still stably extract the feature points of the marker 232 even under high noise (such as ambient light interference) or low light conditions, avoiding matching failures caused by feature blurring.

[0077] During the intelligent business simulation phase, the grid calibration board 231 is removed, the display screen 30 plays a simulated pedestrian flow video, the field of view of the PTZ IPC covers the display screen 30 to detect the pedestrian flow in the video, and sends a command to control the PTZ to rotate the IPC.

[0078] Therefore, this embodiment combines the grid calibration plate 231 and the marker unit 232. The grid calibration plate 231 provides a quantifiable spatial reference, while the marker unit 232 ensures the stability of feature extraction through high-contrast features. This dual design of a standardized physical reference system and highly reliable feature points solves the core problems of inconsistent reference marker points and susceptibility to feature interference in traditional manual inspection. It provides effective technical support for the automated and high-precision detection of the preset position accuracy of the camera 40.

[0079] Continue reading Figure 1 In some embodiments of this utility model, the marking part 232 includes at least two LED beads that emit two different colors of light. Each LED bead is pasted and fixed to the grid intersection on the grid calibration plate 231, and the wavelength of each LED bead is compatible with the infrared filter of the camera 40.

[0080] Among them, LED beads emitting one color of light serve as the main reference marker, which is located at the geometric center of the image; LED beads emitting another color of light serve as auxiliary reference markers, which are symmetrically distributed around the main reference marker to cover different quadrants of the image.

[0081] Furthermore, the two different colors of light include red light and blue light, where red light forms the primary reference marker and blue light forms the secondary reference marker.

[0082] For example, in the grid calibration board 231, one LED bead emitting red light is set as the main reference marker point and four LED beads emitting blue light are set as auxiliary reference marker points. The accuracy of image recognition is improved through multi-feature collaborative constraints.

[0083] The primary reference marker (red dot) serves as the global positioning center, located at the geometric center of the image, which is also the center of the image resolution. For example, the center of a 1920×1080 image is (960, 540). Utilizing the natural sensitivity of the human eye and algorithms to the center, the core location of the target area is quickly located. The red dot is used to determine the global coordinate origin of the image, providing an absolute reference for the subsequent location description of auxiliary reference markers.

[0084] Auxiliary reference markers (blue dots) are used for local distortion correction and redundancy verification. The four blue dots are usually symmetrically distributed around the red dots, such as one each at the top, bottom, left, and right, or distributed in a "cross" or "rectangle" shape to cover different quadrants of the image, such as the upper left, upper right, lower left, and lower right, to ensure coverage of each region of the image.

[0085] By calculating the relative positional relationship between the blue and red dots (such as pixel distance and angular deviation), the distortion parameters of the image (such as radial distortion coefficient and tangential distortion coefficient) are calculated to correct the image distortion caused by lens optical defects or installation tilt.

[0086] For example, in feature extraction algorithms, blue dots are used as auxiliary feature points to form feature pairs with red dots. The reliability of the main reference marker point is verified by the consistency of matching multiple feature pairs (such as excluding single-point mismatches caused by occlusion or noise).

[0087] In addition, the actual scale of the image (pixels / mm) is calculated by the pixel spacing between the blue and red dots (such as horizontal spacing D1 and vertical spacing D2), and a reference is provided for the calculation of rotation angle (such as the angle between the line connecting the two points and the horizontal axis).

[0088] The specific implementation process of the multiple reference markers provided in this embodiment is as follows, taking the detection of a preset position of a PTZ network camera as an example:

[0089] Mesh calibration board 231 acquisition and main reference marker annotation: Use a high-definition camera to photograph the mesh calibration board 231 containing the main reference markers of the IPC preset positions (such as a mesh calibration board 231 covering the horizontal and vertical fields of view); manually or automatically mark the red dot (main reference marker) at the geometric center of the image, ensuring that it is aligned with the center point of the actual physical space (e.g., calibrated using a laser rangefinder). Symmetrically mark four blue dots (auxiliary reference markers) around the red dot.

[0090] Feature extraction and matching: Use ORB or SIFT algorithms to extract feature descriptors (such as orientation, scale, key point coordinates) of red and blue dots in the grid calibration board 231; perform feature matching between the current test image (the image after calling the preset position) and the grid calibration board 231, prioritizing the matching of red dots (main reference markers) and then matching the surrounding blue dots (auxiliary reference markers).

[0091] Error calculation and distortion correction: Calculate the pixel displacement (Δu_red, Δv_red) of the red dot in the test image as the benchmark for the overall offset; calculate the pixel spacing between each blue dot and the red dot (e.g., horizontal spacing D1=100 pixels, vertical spacing D2=100 pixels) and compare it with the theoretical spacing in the grid calibration plate 231 to obtain the distortion coefficients in each direction (e.g., k1=(D1_test – D1_ref) / D1_ref); use the distortion coefficients to correct the test image (e.g., eliminate radial distortion through bilinear interpolation) to ensure the accuracy of subsequent preset position accuracy detection.

[0092] Redundancy verification and result output: Statistically calculate the matching success rate between the red dot and the four blue dots. If it is lower than the threshold, the current image is determined to be invalid (e.g., due to occlusion or mismatch). If the match is successful, calculate the average displacement and standard deviation of all main reference markers and output the preset position offset.

[0093] Therefore, this embodiment of the invention utilizes the known physical coordinates (grid intersections) of the grid calibration plate 231 and the stable light-emitting characteristics of the LED beads to provide the camera 40 with high-precision, repeatable spatial reference markers. Through image acquisition and feature extraction technology, the pixel positions of the reference markers in the image after the preset position is invoked are obtained. Combining the mapping relationship between the physical size of the grid calibration plate 231 and the pixel coordinates (grid pixel ranging method), pixel deviations are converted into actual spatial errors, ultimately achieving automated and quantitative detection of the accumulated accuracy error of the preset position. Furthermore, by simulating intelligent business scenarios through the display screen 30, the camera 40 needs to track the screen content when invoking the preset position, which is closer to the actual monitoring scenario, resulting in more realistic and reliable detection results.

[0094] Continue reading Figure 1 In some embodiments of this utility model, the linear drive assembly 22 includes a support member 221 and a linear drive module 222.

[0095] The support member 221 can be made of high-strength aluminum alloy or steel. Serving as a structural carrier, the support member 221 is mounted on the guide assembly 21 and is adapted to move horizontally. The support member 221 provides stable mounting space and motion constraints for the linear drive module 222 and the grid calibration assembly 23.

[0096] The linear drive module 222 is located on the support member 221 and is adapted to move in the vertical direction; the grid calibration component 23 is located on the linear drive module 222 and is guided and cooperated with the support member 221.

[0097] Furthermore, the linear drive module 222 includes a drive component and a lead screw. The drive component is typically a servo motor or a stepper motor, which outputs rotational torque through the motor shaft to drive the lead screw to rotate.

[0098] The lead screw is rotatably mounted on the support 221. The lead screw (such as a ball screw) is fixedly connected to the output shaft of the drive component via a coupling. The outer surface of the lead screw is machined with a helical groove, which meshes with the inner helical groove of the lead screw nut. The lead screw is connected to the grid calibration assembly 23 via the lead screw nut. When the lead screw rotates, the lead screw nut moves along the lead screw axis, causing the grid calibration assembly 23 to move synchronously.

[0099] The support member 221 has a receiving cavity and a guide groove along the axial direction. The guide groove is connected to the receiving cavity. The drive member and the lead screw are located in the receiving cavity. The mesh calibration component 23 is guided and cooperated with the guide groove. The guide groove is used to constrain the movement trajectory of the mesh calibration component 23 and ensure that each component is coaxially aligned.

[0100] The enclosure provides a closed installation space for the drive unit (motor) and the lead screw, preventing damage to precision components (such as motor bearings and lead screw raceways) from external dust, oil, or mechanical impacts, and extending the service life of the components.

[0101] In the PTZ camera 40 preset position accuracy test scenario, the core function of the linear drive module 222 is to realize the precise lifting and lowering of the grid calibration component 23, thereby completing the connection between the benchmark image acquisition and intelligent business simulation.

[0102] In some embodiments of this utility model, the preset position accuracy testing fixture further includes a first limiting component and a second limiting component; the first limiting component is disposed at the bottom of the support member 221, and the second limiting component is disposed at the top of the support member 221.

[0103] Both the first and second limit components can be limit switches. The limit switches are photoelectric and have a response time of ≤1ms to prevent overtravel collisions. When the device descends to the lowest position, it will trigger a stop.

[0104] In addition, the first and second limit components also adopt a combination design of mechanical blocks and sensors: the mechanical blocks (such as metal blocks or rubber pads) directly block the overtravel of the grid calibration component 23 and provide physical buffer; the sensors (such as proximity switches or photoelectric sensors) detect the position of the grid calibration component 23. When the block is triggered, the sensor sends a stop signal to the control system (such as PLC) to cut off the power supply to the drive components and avoid mechanical impact.

[0105] In some embodiments of this utility model, the guide component 21 includes two guide rails spaced apart and arranged opposite to each other, each guide rail having a scale value; wherein, the linear drive component 22 and the display screen 30 are both disposed on the guide rails.

[0106] The scale values ​​on the guide rail (such as one scale every 10mm) are directly marked on the surface of the guide rail. Technicians can quickly determine the current position by observing the alignment of the slider on the linear drive component 22 (or the display screen 30) with the scale, without the need for additional measuring tools.

[0107] Figure 2 This is a schematic diagram of the networking environment of the preset position accuracy testing system provided in this embodiment of the utility model. Figure 3 These are schematic diagrams of images obtained during the operation of the preset position accuracy testing system provided in this embodiment of the present invention, wherein (a) is a schematic diagram of the reference image and (b) is a schematic diagram of the deviation image. Figure 4 This is a schematic diagram of offset angle calculation provided by an embodiment of the present invention.

[0108] See Figures 2 to 4 The present invention also provides a preset position accuracy testing system, which includes at least one camera 40 and a preset position accuracy testing fixture according to any embodiment, wherein each camera 40 is disposed on the mounting component 10 of the preset position accuracy testing fixture.

[0109] It is understood that the preset position accuracy testing system provided by this utility model, because it includes the aforementioned preset position accuracy testing fixture, possesses all the advantages of the aforementioned preset position accuracy testing fixture.

[0110] See Figures 2 to 4 The specific operation process of the preset position accuracy testing system provided by this utility model is as follows:

[0111] First, set up a preset position accuracy test fixture: After the IPC is fixedly installed, place a grid calibration plate 231 with black and white squares of side length n at a distance L from it. The value of n is the acceptable error set by the user according to the following formula (2-1). For example, if n=1cm and L=200cm, the maximum error range obtained by the user is about 0.28°.

[0112] Finally, the IPCs and PCs are networked using a switch, and the network environment is as follows: Figure 2 As shown.

[0113] Based on the network environment, on the PC, using the IPC's OSD function, preset bit 1 is set as the main reference marker point A and marked with a red dot on the grid calibration board 231 as the main reference marker point for image recognition. The main reference marker point should be placed at the geometric center of the image. Four auxiliary reference marker points (blue dots) are set around the set main reference marker point, as shown in the following style. Figure 3As shown in the figure, the value of N can be obtained by the maximum angle of IPC offset that the user can accept. The calculation formula is formula (2-1). For example, if a blue dot is marked at a distance of N=70cm from the edge of the image, and L is 200cm at this time, the maximum angle of IPC offset that the user can allow is about 19.29°.

[0114] Then, the intelligent services of the IPC (such as human tracking) are started. After running for a set time, it returns to the preset position 1. At this time, the preset position 1 will have a certain offset from the main reference marker point. Then the IPC will save the image G after the offset.

[0115] The computer extracts features from image G to identify whether the image contains 4 auxiliary reference markers. If not all auxiliary reference markers are identified, the offset is determined to be too large. In order to ensure the accuracy of the detection results, this IPC can be measured multiple times (the value of i is used for judgment). If not all auxiliary reference markers are identified for a total of 3 times (the value of i can be assigned), the offset angle of the device is determined to be too large, and the system determines NG.

[0116] If all auxiliary reference markers exist in image G, it is determined that further calculation of preset position offset data is needed. At this time, the horizontal and vertical offset distances are obtained by using the grid pixel ranging method on the offset image G. The IPC that meets the main reference marker determination is measured multiple times (which can be assigned the value j), and the test results are automatically output.

[0117] from Figure 4 It can be deduced that when the horizontal offset is x and the vertical offset is y, the offset angle γ can be obtained for n:

[0118] level: (2-1);

[0119] vertical: (2-2);

[0120] According to the formula above, the values ​​of L and γ are given by the user during the calculation process, so the values ​​n and N required by the tooling environment can be obtained.

[0121] The following method, combining feature extraction with grid pixel ranging, is used to detect the cumulative preset position accuracy error caused by a PTZ camera running for 40 hours:

[0122] First, the offset image G is preprocessed from the input RGB color image. Next, the blue region is segmented: the blue HSV range is defined, a mask is created, and a binary image is output. Then, noise reduction is performed to eliminate small noise points and fill holes inside the origin. Finally, contour detection and circularity filtering are used to count the number of auxiliary reference points, and the result is output to determine if it meets the criteria.

[0123] It should be noted that the prerequisite for performing offset calculation on image G is that the result of feature extraction determination includes all auxiliary reference points.

[0124] First, grid detection is used to detect horizontal and vertical grid lines in the image, and the average spacing between adjacent parallel lines is calculated to determine the pixel side length of a single square as K pixels. Then, red regions are extracted using color thresholding, and the coordinates (xred, yred) of the red region are calculated. Considering that the pixel coordinates of the image center are (xc, yc) = (Q / 2, P / 2), and noting that the IPC resolution is fixed at Q×P during testing, the center coordinates are mapped to the nearest grid intersection. Finally, by calculating the pixel distance between the red point and the center, the horizontal and vertical pixel distances are obtained as xred - Q / 2 and yred - P / 2, respectively. These are converted to squares and rounded to obtain horizontal and vertical distances of (xred - Q / 2) / K and (yred - P / 2) / K, respectively. The number of horizontal and vertical squares is then rounded using a rounding function to obtain the horizontal and vertical square numbers as XF and YF, respectively. The corresponding actual horizontal and vertical distances are nXF and nYF, where n is the actual side length set by the user. Next, using the calculation formula shown in Formula 2-1, Python library functions are used to calculate and output the actual offset angle.

[0125] It should be noted that the fixture needs to be calibrated before formal testing to ensure the correspondence between pixel size and actual grid side length. The maximum allowable offset angle for user observation is also set by adjusting the distance of the blue dot from the image edge. The specific implementation process is as follows: Adjust the distance L between the IPC and the grid image so that the edge of the IPC image aligns with the edge of the grid image, obtaining a definite value for L. This allows the pixel side length K of the grid to be determined by detecting grid lines based on the image resolution. For example, if the offset image detects Z horizontal lines and a vertical resolution of P, the grid pixel side length K = P / (Z+1). Setting the auxiliary reference marker blue dot and the main reference marker red dot can be achieved by combining a light board with red and blue lights. IPCs with different field of view angles need to be calibrated separately using the reference image.

[0126] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A preset position accuracy testing fixture, characterized in that, include: Mounting components, suitable for mounting cameras; Calibration components, including: A guide assembly, located on the front side of the mounting component, is adapted to extend in a horizontal direction; A linear drive assembly is disposed on the guide assembly and is adapted to move in the vertical direction; A grid calibration component is disposed on the linear drive component and adapted to move with the linear drive component to switch between a first position and a second position; The display screen is located on the side of the grid calibration component opposite to the mounting component and is arranged parallel to the grid calibration component; In the first position, the grid calibration component obstructs the display screen, and the camera is used to collect the reference image information of the grid calibration component; in the second position, the grid calibration component removes the obstruction of the display screen, triggering the camera's intelligent service operation.

2. The preset position accuracy testing fixture according to claim 1, characterized in that, The mesh calibration component includes: A grid calibration plate, mounted on the linear drive assembly, is used to provide a two-dimensional grid reference system with known physical coordinates. The size of the grid calibration plate covers the horizontal and vertical fields of view of the camera. At least one marking section is provided at the grid intersection of the grid calibration plate, and each marking section is used to provide a high-contrast feature reference marking point.

3. The preset position accuracy testing fixture according to claim 2, characterized in that, The marking section includes LED beads, which are attached and fixed to the grid intersections on the grid calibration plate.

4. The preset position accuracy testing fixture according to claim 2, characterized in that, The marking section includes at least two LED beads that emit two different colors of light, and each LED bead is attached and fixed to the grid intersection point on the grid calibration plate; In this system, LED beads emitting one color of light serve as the main reference marker, which is located at the geometric center of the image; LED beads emitting another color of light serve as auxiliary reference markers, which are symmetrically distributed around the main reference marker to cover different quadrants of the image.

5. The preset position accuracy testing fixture according to claim 4, characterized in that, The two different colors of light include red light and blue light, wherein red light forms the main reference marker point and blue light forms the auxiliary reference marker point.

6. The preset position accuracy testing fixture according to any one of claims 1 to 5, characterized in that, The linear drive component includes: A support member is disposed on the guide assembly and is adapted to move horizontally along the guide assembly; A linear drive module is disposed on the support member and is adapted to move in the vertical direction; The grid calibration component is located in the linear drive module and cooperates with the support member for guidance.

7. The preset position accuracy testing fixture according to claim 6, characterized in that, The linear drive module includes: A driving component is provided on the support component; A lead screw is rotatably mounted on the support member, the lead screw is driven by the output shaft of the drive member, and the lead screw is connected to the grid calibration assembly through a lead screw nut; The support member has a receiving cavity and a guide groove along the axial direction. The guide groove communicates with the receiving cavity. The drive member and the lead screw are located in the receiving cavity. The grid calibration component is guided and engaged with the guide groove.

8. The preset position accuracy testing fixture according to claim 6, characterized in that, It also includes a first limiting component and a second limiting component; The first limiting component is located at the bottom of the support member, and the second limiting component is located at the top of the support member.

9. The preset position accuracy testing fixture according to any one of claims 1 to 5, characterized in that, The guide component includes two guide rails spaced apart and arranged opposite to each other, each guide rail having a scale value; Both the linear drive assembly and the display screen are mounted on the guide rail.

10. A preset position accuracy testing system, characterized in that, It includes at least one camera and a preset position accuracy test fixture as described in any one of claims 1 to 9, wherein each camera is disposed on a mounting component of the preset position accuracy test fixture.

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