A method for adaptive alignment control of a spot and a target

Abstract

The application relates to a self-adaptive alignment control method for a light spot and a target, which comprises the following steps: an imaging device collects a current picture of the target, copies the image and inputs the image into two parallel preprocessing channels to respectively perform target extraction and light spot extraction; the outermost maximum closed contour in the ROI of the target is tracked and locked, the top corner is extracted based on edge contour approximation, the de-distorted corner point coordinates are obtained, and the average value of the corner point displacement is calculated as the pixel displacement of the target as a whole; laser light spot state detection is performed to detect the pixel position of the laser light spot in the current image. When the laser light spot is located outside the target range, coarse search processing is triggered.

Description

Technical Field

[0001] This application relates to an adaptive alignment control method for light spot and target, which can be used in the technical field of building health monitoring. Background Technology

[0002] In building structural health monitoring, it is usually necessary to acquire the three-dimensional displacement of key measuring points in real time, that is, the displacement of key measuring points in three orthogonal directions, in order to determine whether the building structure has been damaged or destroyed.

[0003] The equipment used may include: an imaging device, such as an industrial camera, fixed on a rigid support with its optical axis direction remaining unchanged after installation; a two-axis gimbal, mounted on the same rigid support, driving the laser displacement meter to rotate in both horizontal and pitch degrees of freedom, receiving angle commands from the control unit; a laser displacement meter, fixed on the gimbal and rotating with it, used to emit laser light and receive reflected signals, measuring the slant distance from the imaging device to the target surface; an inclinometer, fixed to the rigid support, outputting in real time the tilt angle along the vertical direction of the camera and the tilt angle along the horizontal direction of the camera; and a target, mounted on the surface of each structure to be monitored, containing a rigidly connected matrix-coded identity feature area and a geometric measurement pattern. The target surface must effectively reflect the laser light emitted by the laser displacement meter, and the target mounting surface should be approximately perpendicular to the camera's line of sight. Its working principle is based on the known physical side length of the target and the pixel side length extracted from the image, using camera calibration parameters to estimate the approximate distance from the target to the camera.

[0004] However, existing technologies often encounter problems such as laser spot misalignment, overshooting, or loss during the switching between different targets. This not only reduces the accuracy of alignment but also slows down the operation, greatly affecting the efficiency and accuracy of the operation. Summary of the Invention

[0005] This application provides an adaptive alignment control method for a light spot and a target. It employs a control approach combining coarse search, fine search, and backoff processing. The coarse search quickly relocates the target, the fine search further moves the light spot to the target center, and the backoff processing re-enters the search process when verification fails or the light spot is lost. This adaptive alignment control method can simultaneously balance search speed and alignment accuracy, making it suitable for long-distance and multi-target monitoring scenarios.

[0006] This application relates to an adaptive alignment control method for a light spot and a target, comprising the following steps:

[0007] S21. Image acquisition and preprocessing;

[0008] The imaging device acquires the current image of the target, copies the image, and inputs it into two parallel preprocessing channels for target extraction and spot extraction, respectively.

[0009] S22, Target identification and two-dimensional displacement extraction of the target;

[0010] Within the ROI of the target, the outermost maximum closed contour is tracked and locked. The vertex corner is extracted based on the approximation of the edge contour to obtain the distortion-free corner coordinates. The mean of the corner displacement is calculated as the pixel displacement of the target as a whole.

[0011] S23. Laser spot status detection: Detects the pixel position of the laser spot in the current image;

[0012] When the laser spot is outside the target area, a coarse search process is triggered, including the following sub-steps:

[0013] (1) Search trajectory planning

[0014] The control unit drives the two-axis gimbal to move the laser displacement meter from the current initial pointing angle. Initially, it scans outward in a radial pattern according to the preset Archimedean spiral trajectory; its horizontal angular displacement... With pitch angular displacement The parametric equation is defined as:

[0015]

[0016]

[0017] In the formula, The initial helix radius, The pitch factor is... This is the angular velocity control constant;

[0018] (2) Step size control and boundary constraints

[0019] Set the gimbal coarse adjustment step angle threshold to: The single-step pixel displacement of the light spot corresponding to this step angle in the imaging image should be less than half the width of the current target ROI region, that is, satisfying:

[0020]

[0021] In the formula, The pixel width of the current target in the image. The equivalent focal length in the horizontal direction, in pixels;

[0022] (3) Interruption triggering criteria

[0023] In each physical step cycle of the coarse search, the vision processing module acquires the current frame image of the camera in real time. Once it detects that the light spot has invaded the target ROI area, that is, when the calculated pixel coordinates of the light spot fall within the target rectangle boundary, the control unit immediately interrupts the coarse search program, locks the current gimbal angle coordinates, and automatically triggers the cross-verification of visual ranging and laser ranging.

[0024] If the cross-validation is true and the spot has not yet met the center threshold, the fine search continues, including the following sub-steps:

[0025] The system uses the center pixel coordinates of the light spot Pixel coordinates of the center of the target ROI Euclidean distance As the objective function for control feedback:

[0026]

[0027] The control unit adjusts the pan-tilt-zoom (PTZ) horizontal angle via negative feedback. and pitch angle The gradient approximation method is used to alternately adjust the dual-axis angles, and its iterative update control law formula is as follows:

[0028]

[0029]

[0030] In the formula, This represents the current iteration step. and These represent the pixel deviations of the light spot in the horizontal and vertical directions of the image, respectively. This is a dynamic adaptive step size factor. The equivalent focal length in the vertical direction is expressed in pixels.

[0031] Preferably, the adaptive step size factor The calculation formula is:

[0032]

[0033] In the formula, The initial reference step size preset for the system; This is the initial pixel distance at the moment the system enters the fine-grained search. For the first Real-time pixel distance of the step The step size decay control index; based on Size adjustment step size factor The size of the target allows the gimbal to quickly approach the target until the light spot is close to the center of the target. When the target function value calculated over multiple consecutive frames is stable, and... When the distance is less than the set threshold, the system determines that the alignment is successful, locks the dual axes of the gimbal, maintains the attitude, and performs laser ranging to measure the distance to the target.

[0034] During the fine search process, if the light spot is lost or any cross-validation returns a false result, the process will revert to the coarse search process. When reverting to the coarse search process, the initial search radius will be expanded and the number of reverts will be recorded. When the number of reverts exceeds the set number, the target status will be marked as LOST and an alarm will be triggered.

[0035] The obtained pixel displacement Combined with the measured target distance The displacement is converted into physical displacement in the visual plane; the displacement value of the device coordinate system is converted to the gravity coordinate system according to the camera tilt angle, so as to synthesize a three-dimensional displacement vector in the gravity coordinate system; wherein, the camera tilt angle is output in real time by a tilt meter fixed to the rigid support.

[0036] According to the adaptive alignment control method for laser spot and target proposed in this application, in order to address the problems of laser spot misalignment, target overshooting or loss that may occur during the switching of multiple targets, this application adopts a control method that combines coarse search, fine search and backoff processing, which can simultaneously take into account search speed and alignment accuracy, and is suitable for long-distance and multi-target monitoring scenarios. Attached Figure Description

[0037] Figure 1 This is a flowchart illustrating an adaptive alignment control method for a light spot and a target according to this application. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

[0039] This application provides an adaptive alignment control method for a light spot and a target. The target is used for displacement monitoring to measure the three-dimensional displacement of the structure. The vision module can simultaneously identify the characteristics of the target within the field of view, establishing a region of interest (ROI) for the target. This application can select between coarse and fine search based on the pre-positioning accuracy, balancing efficiency and reliability. If the light spot detection module determines that the light spot is currently completely outside the target's range, the system automatically triggers a coarse search mechanism to quickly relocate the target. The fine search is used to further move the light spot to the target center, aiming to achieve high-precision physical alignment between the light spot center and the target's geometric center.

[0040] Specifically, when the laser monitors the target, the vision module identifies the pixel coordinates of the target within the current frame. Based on the target's position offset within the frame, trigonometric functions are used to roughly calculate the horizontal and vertical angles that the gimbal needs to adjust, controlling the gimbal to rotate to the estimated approximate position. Based on the pre-positioned state, the following search strategies can be selected:

[0041] Coarse search strategy: If the laser spot does not enter the ROI range of the target after pre-positioning, the coarse search process is triggered, and the spot position is found through visual feedback closed-loop control.

[0042] Fine-grained search strategy: If the laser spot has entered the ROI of the target after pre-positioning, but is not in the center, the coarse search is skipped, and the fine-grained search process is directly initiated. An approximation algorithm is used to move the spot to the center of the target. After alignment, cross-validation is performed using visual coarse distance and laser range measurement. Once confirmed to be correct, the target is put into continuous monitoring mode.

[0043] The target measurement method according to this application includes the following steps:

[0044] (1) The target image is acquired using an imaging device. The target image includes a black and white target pattern and a laser spot. The image is copied and input into parallel preprocessing channels, namely the target extraction channel and the laser spot extraction channel. Bilateral filtering is performed in the target extraction channel to reduce noise, and adaptive local mean threshold segmentation is used to convert the black and white boundary into a high-contrast binary image of the target. In the laser spot extraction channel, high threshold global threshold segmentation is used to filter out the background and output a binary image containing only the core domain of the bright spot. The high threshold global threshold segmentation means that the entire image is binarized with a high uniform gray level threshold, retaining the overexposed laser spot pixels and filtering out the rest of the background. The threshold can be set empirically.

[0045] (2) In the image output by the target extraction channel, track and lock the outermost maximum closed contour within the region of interest (ROI); use the RDP (Ramer-Douglas-Peucker) polygon approximation algorithm to simplify and approximate the contour, take the simplified approximate polygon with 4 vertices, and initially extract the coordinates of the 4 vertices of the rectangular target at the current time; perform sub-pixel level fine localization on each detected coarse corner point to obtain the corner coordinates with sub-pixel precision distortion removal.

[0046] The sub-pixel precision distortion correction of corner coordinates involves establishing a search window centered on the coarse corner point. Based on the image gradient distribution along the two edge directions within the corner's neighborhood, an iterative weighted least squares method is used to fit the edge normal equations, and the precise intersection of the two edge lines is obtained as the sub-pixel corner coordinates. This method eliminates discrete gridding errors and serves as the physical source data input for subsequent displacement extraction. Then, corner distortion correction is performed using a pre-calibrated camera intrinsic parameter matrix. and distortion coefficient Distortion correction is performed independently on the coordinates of the four sub-pixel reference vertices to obtain their true physical projection coordinates on the distortion-free ideal imaging surface.

[0047]

[0048]

[0049] in , These are the equivalent focal lengths in the horizontal and vertical directions, respectively, in pixels; , The pixel coordinates of the camera's optical center in the image. The tilt coefficient; , , The radial distortion coefficient is... , denoted as the tangential distortion coefficient.

[0050] (3) Calculate the displacement of the target corner pixel: Let the initial state of the target corner pixel coordinates be... Currently Then pixel displacement , The average displacement of the four corner points is taken as the overall pixel displacement of the target. , .

[0051] (4) Detect the pixel position of the laser spot in the current image and calculate the Euclidean distance between the center of the spot and the center of the target ROI. and the calculated Euclidean distance The set Euclidean distance threshold The location of the light spot is determined by comparison.

[0052] (5) If And if the light spot is within the target area, then it is determined that the light spot is aligned with the target center; if If the light spot is within the target range, it is determined that the light spot is on the target but deviates from the target center, and a fine search is directly triggered to gradually move the light spot to the target center; if the light spot is outside the target range, coarse search and fine search are performed in sequence until it is determined that the light spot is aligned with the target center.

[0053] (6) The laser displacement meter emits a laser and receives the reflected signal to measure the target distance. .

[0054] (7) Combine the data obtained in the preceding steps with the equipment attitude data output by the inclinometer to form a three-dimensional displacement vector in the gravity coordinate system.

[0055] This application, through the aforementioned target measurement process, can complete the entire process from acquiring an image of a target to outputting the three-dimensional displacement of the target in its gravity coordinate system. Specifically, it includes the following steps:

[0056] S21. Image Acquisition and Preprocessing. The industrial camera acquires the current image. Due to the extreme grayscale contrast between the black and white target pattern and the high-energy laser spot in the image, the system copies the image and inputs it into two parallel preprocessing channels:

[0057] The first channel, namely target extraction, performs bilateral filtering for noise reduction and adopts adaptive local mean thresholding to transform the black and white boundary into a high-contrast binary image of the target.

[0058] The second channel, namely laser spot extraction, uses high-threshold global threshold segmentation to filter out the background and output a binarized image containing only the core domain of the bright spot.

[0059] S22. Target identification and 2D displacement extraction of the target. Perform the following sub-steps:

[0060] S221. Vertex extraction based on edge contour approximation. In the image output by the first channel, the outermost maximum closed contour is tracked and locked within the target ROI; the RDP polygon approximation algorithm is used to simplify the contour into a polygon, and an approximate polygon with 4 vertices after simplification is taken to initially extract the coordinates of the 4 vertices of the rectangular target at the current time.

[0061] S222. Perform subpixel-level fine localization on each detected coarse corner point to obtain the corner point coordinates with subpixel precision distortion correction.

[0062] S223, Pixel displacement calculation. Let the initial pixel coordinates of the target corner be... Currently Then pixel displacement , The average displacement of the four corner points is taken as the overall pixel displacement of the target. , .

[0063] S23, Laser spot status detection.

[0064] S231. The vision module detects the pixel position of the laser spot in the current image and calculates the Euclidean distance between the center of the laser spot and the center of the target ROI. :

[0065]

[0066] in The current pixel coordinates of the light spot. The coordinates of the center pixel of the target ROI.

[0067] S232. The position of the light spot is determined, and the following three cases are identified:

[0068] (1) If If the light spot is within the target area, it is determined that the light spot is aligned with the target center. The threshold for allowing the light spot to deviate from the target center can be specified according to the actual size of the target. At this point, S234 is first entered to perform cross-validation of visual ranging and laser ranging. If the validation is true, S24 laser ranging is then executed.

[0069] (2) If If the light spot is within the target area, it is determined that the light spot falls on the target but deviates from the target center, and a fine search is directly triggered to gradually move the light spot to the target center.

[0070] (3) If the light spot is outside the target range, trigger coarse search processing.

[0071] S233, Coarse Search. The control unit drives the two-axis gimbal to move the laser displacement meter, scanning outward in a radial pattern along a preset Archimedean spiral trajectory from the current pointing angle. During the scanning process, the vision processing module acquires images in real time; once a light spot is detected intruding into the target ROI area, the control unit immediately interrupts the scanning and locks the current gimbal angle coordinates, then proceeds to S234 to perform cross-validation of visual ranging and laser ranging. If the cross-validation is true and the light spot has not yet met the center threshold, then proceeds to S235 to perform a fine search; if the cross-validation is false, then proceeds to S236 for backtracking.

[0072] S234. The laser displacement meter emits a laser and receives the reflected signal to measure the distance in the current optical path direction. Cross-validation of visual ranging and laser ranging is performed to ensure that the absolute difference between the two is less than a set threshold. ,Right now If the detected light spot is confirmed to be generated by laser irradiation on the target surface, rather than ambient reflection or other light sources, the cross-validation is returned as true; otherwise, the cross-validation is returned as false.

[0073] S235, Fine-tuning Search. Using the pixel distance between the light spot and the target center as the objective function, an adaptive step-size gradient approximation method is employed. The pan-tilt-zoom (PTZ) angle and elevation angle are alternately adjusted to gradually move the light spot towards the target center, aiming to achieve high-precision physical alignment between the light spot center and the target's geometric center. After reaching the fine-tuning search accuracy threshold, S234 cross-validation is performed again; if the validation is true, S24 laser ranging is performed. If the light spot is lost during the fine-tuning search, or if any S234 cross-validation returns false, the process proceeds to S236 for backtracking.

[0074] S236. Rollback Processing. The system rolls back to the coarse search in S233 according to the preset state machine (the initial search radius is expanded during rollback to avoid oscillation), and records the number of rollbacks. When the number of rollbacks exceeds 3, the target state is marked as LOST and an alarm is triggered.

[0075] S24. Laser Ranging. A laser displacement meter emits a laser and receives the reflected signal to measure the distance to a target. .

[0076] S25. Physical displacement calculation and 3D data fusion, 3D displacement synthesis. The data obtained in the preceding steps are synthesized into a 3D displacement vector in the gravity coordinate system, executed according to the following sub-steps:

[0077] S251, Physical displacement calculation. Calculate the pixel displacement obtained in S223. Combined with the laser distance measured by S24 This is converted into physical displacement within the visual plane. Considering the longitudinal displacement of the target along the camera's line of sight in long-distance monitoring of large-span or tall structures... This can cause perspective distortion in the image, also known as the "near objects appear larger, far objects appear smaller" effect, resulting in pseudo-displacement errors in the lateral direction. To further improve the accuracy of 3D displacement calculation, the system introduces a perspective distortion correction term into the pixel displacement conversion formula. and The revised formula for the physical displacement of the device coordinate system is:

[0078]

[0079]

[0080] Simultaneously, calculation Absolute longitudinal displacement in the direction:

[0081]

[0082] in, The distance to the target in its initial state, and the perspective distortion correction term. and The calculation formula is as follows:

[0083]

[0084]

[0085] S252. Convert the displacement values ​​of the equipment coordinate system to the gravity coordinate system based on the camera tilt angle. Under normal operating conditions where the equipment support attitude is stable, the initial tilt angle data θ0 and φ0 are used as the fixed transformation references of the equipment coordinate system relative to the gravity coordinate system; when the deviation of the current tilt angle from the initial tilt angle exceeds a threshold, the result of this cycle is marked as low-confidence failure data. The rotation matrix is ​​constructed in the order of first rotating φ0 around the camera's Y-axis, and then rotating θ0 around the X-axis:

[0086]

[0087] Convert device coordinates to gravity coordinates:

[0088]

[0089] After conversion For horizontal and lateral displacement, For vertical settlement / uplift displacement, These represent horizontal and longitudinal displacements, and the three directly correspond to the monitoring direction of the equipment.

[0090] More specifically, in the coarse search of step S233, if the spot detection module determines that the spot is currently completely outside the target range, the system automatically triggers the coarse search mechanism and executes the following sub-steps:

[0091] (1) Search trajectory planning: The control unit drives the two-axis gimbal to move the laser displacement meter from the current initial pointing angle. Initially, it scans outward radially along a pre-defined Archimedean spiral trajectory. Its horizontal angular displacement... With pitch angular displacement The parametric equation is defined as:

[0092]

[0093]

[0094] In the formula, The initial helix radius, The pitch factor is... ω is the angular velocity control constant.

[0095] (2) Step size control and boundary constraints

[0096] Set the gimbal coarse adjustment step angle threshold to: To prevent the scanning trajectory from crossing the target and causing missed detections, the single-step pixel displacement of the spot corresponding to this step angle in the imaging image should be strictly less than half the width of the current target ROI region, i.e., satisfying:

[0097]

[0098] In the formula, The pixel width of the current target in the image.

[0099] (3) Interruption triggering criteria

[0100] During each physical step cycle of the coarse search, the vision processing module acquires the current frame image from the camera in real time. Once a spot is detected intruding into the target ROI region, i.e., the calculated spot pixel coordinates fall within the target rectangle boundary, the control unit immediately interrupts the coarse search program, locks the current gimbal angle coordinates, and automatically triggers the cross-validation of visual ranging and laser ranging in S234. If the cross-validation is true and the spot has not yet met the center threshold, the process proceeds to S235 to continue the fine search.

[0101] In the fine search of step S235, the system uses the center pixel coordinates of the light spot. Pixel coordinates of the center of the target ROI Euclidean distance As the objective function for control feedback:

[0102]

[0103] The control unit adjusts the pan-tilt-zoom (PTZ) horizontal angle via negative feedback. and pitch angle The gradient approximation method is used to alternately adjust the dual-axis angles, and its iterative update control law formula is as follows:

[0104]

[0105]

[0106] In the formula, This represents the current iteration step. and These represent the pixel deviations of the light spot in the horizontal and vertical directions of the image, respectively. This is a dynamic adaptive step size factor. The equivalent focal length in the vertical direction is expressed in pixels.

[0107] The dynamic adaptive step size factor is calculated using the following formula:

[0108]

[0109] In the formula, The initial reference step size preset by the system, This is the initial pixel distance at the moment the system enters the fine-grained search. For the first Real-time pixel distance of the step This is the step size decay control index.

[0110] (1) Dynamic control effect: When the light spot deviates far from the center of the target ( Larger), step size factor Maintain a relatively large value to achieve rapid approach of the gimbal; when the light spot approaches the center of the target ( Step size factor Automatically exhibits power-law smooth decay.

[0111] (2) Termination criteria: When consecutive Frame (preferably) The calculated objective function value is stable and satisfies Upon successful alignment, the system immediately locks the dual axes of the gimbal, maintains the attitude, and executes S24 laser ranging.

[0112] Although the embodiments disclosed in this application are as described above, the content is merely for the purpose of facilitating understanding of this application and is not intended to limit this application. Any person skilled in the art to which this application pertains may make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in this application; however, the scope of patent protection of this application shall still be determined by the scope defined in the appended claims.

Claims

1. An adaptive alignment control method for a light spot and a target, characterized in that, Includes the following steps: S21. Image acquisition and preprocessing; The imaging device acquires the current image of the target, copies the image, and inputs it into two parallel preprocessing channels for target extraction and spot extraction, respectively. S22, Target identification and two-dimensional displacement extraction of the target; Within the ROI of the target, the outermost maximum closed contour is tracked and locked. The vertex corner is extracted based on the approximation of the edge contour to obtain the distortion-free corner coordinates. The mean of the corner displacement is calculated as the pixel displacement of the target as a whole. S23. Laser spot state detection: Detects the pixel position of the laser spot in the current image; When the laser spot is outside the target area, a coarse search process is triggered, including the following sub-steps: (1) Search trajectory planning The control unit drives the two-axis gimbal to move the laser displacement meter from the current initial pointing angle. Initially, it scans outward in a radial pattern according to the preset Archimedean spiral trajectory; its horizontal angular displacement... With pitch angular displacement The parametric equation is defined as: In the formula, The initial helix radius, The pitch factor is... This is the angular velocity control constant; (2) Step size control and boundary constraints Set the gimbal coarse adjustment step angle threshold to: The single-step pixel displacement of the light spot corresponding to this step angle in the imaging image should be less than half the width of the current target ROI region, that is, satisfying: In the formula, The pixel width of the current target in the image. The equivalent focal length in the horizontal direction, in pixels; (3) Interruption triggering criteria In each physical step cycle of the coarse search, the vision processing module acquires the current frame image of the camera in real time. Once it detects that the light spot has invaded the target ROI area, that is, when the calculated pixel coordinates of the light spot fall within the target rectangle boundary, the control unit immediately interrupts the coarse search program, locks the current gimbal angle coordinates, and automatically triggers the cross-verification of visual ranging and laser ranging.

2. The adaptive alignment control method according to claim 1, characterized in that, If the cross-validation is true and the spot has not yet met the center threshold, continue with the fine search, including the following sub-steps: The system uses the center pixel coordinates of the light spot Pixel coordinates of the center of the target ROI Euclidean distance As the objective function for control feedback: The control unit adjusts the pan-tilt-zoom (PTZ) horizontal angle via negative feedback. and pitch angle The gradient approximation method is used to alternately adjust the dual-axis angles, and its iterative update control law formula is as follows: In the formula, This represents the current iteration step. and These represent the pixel deviations of the light spot in the horizontal and vertical directions of the image, respectively. This is a dynamic adaptive step size factor. The equivalent focal length in the vertical direction is expressed in pixels.

3. The adaptive alignment control method according to claim 2, characterized in that, Dynamic adaptive step size factor The calculation formula is: In the formula, The initial reference step size preset for the system; This is the initial pixel distance at the moment the system enters the fine-grained search. For the first Real-time pixel distance of the step The step size decay control index; according to Size adjustment step size factor The size allows the gimbal to quickly approach the target until the light spot is close to the center of the target.

4. The adaptive alignment control method according to claim 3, characterized in that, When the objective function value calculated over multiple consecutive frames is stable, and When the distance is less than the set threshold, the system determines that the alignment is successful, locks the dual axes of the gimbal, maintains the attitude, and performs laser ranging to measure the distance to the target.

5. The adaptive alignment control method according to claim 3, characterized in that, If a spot is lost or any cross-validation returns false during the fine search process, the process will revert to the coarse search process. When reverting to coarse search processing, the initial search radius is expanded and the number of reverts is recorded; when the number of reverts exceeds the set number, the target status is marked as LOST and an alarm is triggered.

6. The adaptive alignment control method according to claim 4, characterized in that, The obtained pixel displacement Combined with the measured target distance The displacement is converted into physical displacement in the visual plane; the displacement value of the device coordinate system is converted to the gravity coordinate system according to the camera tilt angle, so as to synthesize a three-dimensional displacement vector in the gravity coordinate system; wherein, the camera tilt angle is output in real time by a tilt meter fixed to the rigid support.

Images