Target center positioning method and device under rotation angle restriction condition

Abstract

The application relates to a target center positioning method and device under a rotation angle limited condition, a target point set is constructed, an initial rotation center is fitted according to the target point set, and the target is moved to the initial rotation center; a rotating mechanism is rotated to a first rotation angle, an axial focus of the target is performed through a microscopic imaging device, so that an imaging plane reference position is determined; the rotating mechanism is rotated to a second rotation angle, the target is moved to clear focus along a first plane motion axis direction, so that a constraint condition that a displacement in a second plane motion axis direction is equal to a displacement in the first plane motion axis direction is constructed; the rotating mechanism is rotated to a third rotation angle, and the target is clear focus, and an axial displacement relative to the imaging plane reference position is recorded; according to the axial displacement and the constraint condition, the displacement of the target in the two plane motion axis directions is determined, and a compensation motion is performed, so that the center of the target is aligned with the rotation center of the rotating mechanism.

Description

Technical Field

[0001] This application relates to the fields of precision positioning and machine vision technology, specifically to a method and apparatus for target center positioning under conditions of limited rotation angle. Background Technology

[0002] In applications such as precision assembly, micromanipulation, and optical inspection, rotating mechanisms are often used to adjust the angle of a target. To prevent the target from shifting during rotation, it is usually necessary to precisely adjust the target to the center of rotation. In current related technologies, when a rotating mechanism can achieve a rotation angle close to or reaching 180°, the displacement of the target in each axis direction in the plane can be decoupled through displacement changes under symmetrical angles, thereby achieving precise positioning of the rotation center.

[0003] However, in practical engineering applications, due to limitations in mechanism structure, spatial interference, or functional requirements, rotating mechanisms often can only achieve a limited rotation angle of no more than 90°. Under this condition, each axis has a coupling effect on the target's motion, and traditional methods struggle to decouple the target's axial offsets within the plane, resulting in limited positioning accuracy of the rotation center. On the other hand, in scenarios requiring high-precision centering, high-magnification microscopic imaging is typically used to improve measurement accuracy. However, the field of view of high-magnification microscopic imaging is limited. If the target is not adjusted to a position close to the rotation center before rotation, it is highly likely to exceed the field of view of the microscopic imaging during rotation, making high-precision positioning impossible.

[0004] Therefore, under the conditions of limited rotation angle and limited field of view of microscopic imaging, how to achieve high-precision positioning and compensation of the rotation center while ensuring that the target is always within the imaging field of view has become an urgent technical problem to be solved. Summary of the Invention

[0005] This application provides a target center positioning method and apparatus under conditions of limited rotation angle, which can solve the technical problem that it is impossible to effectively decouple the offset of each axis in the plane and the target rotation center is difficult to accurately locate under conditions of limited rotation angle and limited field of view of high magnification microscopy.

[0006] To achieve the above objectives, this application provides the following technical solution: In a first aspect, embodiments of this application provide a target center localization method under conditions of limited rotation angle, the method comprising: The rotating mechanism is controlled to rotate to multiple rotation angles, and the planar position information of the target at multiple rotation angles is acquired by the top-view imaging device to obtain the target point set; An initial rotation center is fitted based on the target point set, and the planar motion platform is controlled to move the target to the initial rotation center; wherein, the planar motion platform represents the actuator used to move the target along two orthogonal directions in the plane; Control the rotating mechanism to rotate to the first rotation angle, and use the microscopic imaging device to focus the target axially, and determine the axial position when the focus is clear as the reference position of the imaging plane. While maintaining a clear focus, the axial position of the microscopic imaging device remains unchanged. The rotating mechanism is controlled to rotate to a second rotation angle, and the planar motion platform is controlled to move the target along the first planar motion axis until the target is in focus again. This establishes a constraint condition that the offset of the target in the second planar motion axis direction is equal to the offset in the first planar motion axis direction. The first and second planar motion axis directions are two orthogonal directions. The difference between the first and second rotation angles is 90 degrees. Control the rotating mechanism to rotate to the third rotation angle, and adjust the microscopic imaging device along the axial direction of the microscopic imaging device until the target is in focus. Record the axial displacement of the microscopic imaging device relative to the reference position of the imaging plane; wherein the maximum angle among the first rotation angle, the second rotation angle, and the third rotation angle does not exceed 90 degrees. Based on the axial displacement and constraints, determine the offset of the target in the first plane motion axis direction and the second plane motion axis direction; The offset control planar motion platform performs compensating motion to align the center of the target with the rotation center of the rotating mechanism.

[0007] In some embodiments of this application, fitting an initial rotation center based on a target point set includes: Determine the first measurement uncertainty in the radial direction and the second measurement uncertainty in the tangential direction for each sampling point in the target point set; wherein the first measurement uncertainty is greater than the second measurement uncertainty; An isotropic uncertainty model is established based on the first and second measurement uncertainties; wherein, the isotropic uncertainty model is used to characterize the characteristic that each sampling point has different measurement uncertainties in the radial and tangential directions; The initial rotation center is obtained by weighted fitting of the target point set based on the non-isotropic uncertainty model.

[0008] In some embodiments of this application, controlling the planar motion platform to move the target to the initial center of rotation includes: The mapping relationship between the first planar motion axis direction and the pixel coordinate system of the top-view imaging device, and the mapping relationship between the second planar motion axis direction and the pixel coordinate system of the top-view imaging device are respectively calibrated; Based on the mapping relationship, the pixel difference between the position of the initial rotation center in the pixel coordinate system of the top-view imaging device and the current position of the target is converted into the actual movement distance of the planar motion platform; Based on the actual movement distance, the planar motion platform is controlled to move the target to the initial rotation center.

[0009] In some embodiments of this application, after fitting an initial rotation center based on the target point set and controlling the planar motion platform to move the target to the initial rotation center, the method further includes: The target's position information is acquired using a top-view imaging device to determine whether the target is located at the initial rotation center; If the target is not located at the initial rotation center, repeat the process of controlling the plane motion platform to move the target to the initial rotation center until it is determined that the target is located at the initial rotation center.

[0010] In some embodiments of this application, determining the offset of the target in the first planar motion axis direction and the second planar motion axis direction based on the axial displacement and constraint conditions includes: Obtain the first displacement of the target moving along the first plane motion axis at the second rotation angle; The axial displacement of the microscopic imaging device along the axial direction of the microscopic imaging device is obtained at the third rotation angle; based on the first rotation angle, the second rotation angle, the third rotation angle, the axial displacement, and the first displacement, the offset of the target in the direction of the second plane motion axis is determined. Based on the constraints, the offset of the target in the direction of the first plane motion axis is determined to be equal to the offset in the direction of the second plane motion axis.

[0011] In some embodiments of this application, determining the offset of the target in the direction of the second planar motion axis based on the first rotation angle, the second rotation angle, the third rotation angle, the axial displacement, and the first displacement includes: Determine the first sine difference and the first cosine difference between the first rotation angle and the second rotation angle; Determine the second sine difference and the second cosine difference between the third rotation angle and the second rotation angle; The offset of the target in the direction of the second planar motion axis is determined based on the first sine difference, the first cosine difference, the second sine difference, the second cosine difference, the axial displacement, and the first displacement.

[0012] In some embodiments of this application, when the first rotation angle is 0 degrees, the direction of the first planar motion axis is perpendicular to the axial direction of the microscopic imaging device; When the second rotation angle is 90 degrees, the direction of the first planar motion axis is parallel to the axial direction of the microscopic imaging device.

[0013] Secondly, embodiments of this application provide a target center positioning device, including a processor and a memory storing processor-executable instructions; when the instructions are executed by the processor, the above-mentioned target center positioning method under the condition of limited rotation angle is implemented.

[0014] Thirdly, embodiments of this application provide a target center positioning system, including: a rotation mechanism, a top-view imaging device, a planar motion platform, a microscopic imaging device, and a target center positioning device; the target center positioning device is used to perform the above-described target center positioning method under the condition of limited rotation angle.

[0015] Fourthly, embodiments of this application provide a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the above-described target center positioning method under the condition of limited rotation angle. Attached Figure Description

[0016] To more intuitively illustrate the prior art and this application, several exemplary figures are provided below. It should be understood that the specific shapes and structures shown in the figures should not generally be regarded as limiting conditions for implementing this application; for example, based on the technical concept disclosed in this application and the exemplary figures, those skilled in the art are able to easily make conventional adjustments or further optimizations to the addition / reduction / classification, specific shapes, positional relationships, connection methods, size ratios, etc. of certain units (components).

[0017] Figure 1 A schematic diagram illustrating the implementation process of the target center positioning method under the condition of limited rotation angle provided in the embodiments of this application; Figure 2 A schematic diagram of the working scenario for the target center positioning method under the condition of limited rotation angle provided in the embodiments of this application; Figure 3 A schematic diagram of the fitting rotation center provided in the embodiments of this application; Figure 4 A schematic diagram illustrating the determination of radial offset provided in an embodiment of this application; Figure 5 A schematic diagram of the geometric relationship of the shaft system offset during the fine positioning stage provided in the embodiments of this application; Figure 6 This is a schematic diagram of the composition of the target center positioning device provided in the embodiments of this application; Figure 7 This is a schematic diagram of the composition structure of the target center positioning system provided in the embodiments of this application.

[0018] Figure label: Target center positioning device 1, processor 11, memory 12, communication interface 13, bus 14; Target center positioning system 0, rotation mechanism 2, top-view imaging device 3, planar motion platform 4, microscopic imaging device 5. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. Any combination of different embodiments is possible.

[0020] In the description of this application: unless otherwise stated, "a plurality of" means two or more. The terms "first," "second," "third," etc., in this application are intended to distinguish the objects referred to and do not have any special meaning in terms of technical connotation (e.g., they should not be construed as an emphasis on importance or order). Expressions such as "including," "comprising," and "having" also mean "not limited to" (certain units, components, materials, steps, etc.).

[0021] This application provides a target center localization method under conditions of limited rotation angle, such as... Figure 1 As shown, the target center localization method under the condition of limited rotation angle may include the following steps: Step 101: Control the rotating mechanism to rotate to multiple rotation angles, and use the top-view imaging device to collect the planar position information of the target at multiple rotation angles to obtain the target point set.

[0022] In the embodiments of this application, the target center positioning device can control the rotating mechanism to rotate to multiple rotation angles, and collect the planar position information of the target at multiple rotation angles through the top-view imaging device to obtain the target point set.

[0023] In the embodiments of this application, the rotating mechanism is used to carry the target and drive the target to rotate around its rotation axis in the plane to different angles; the rotation angle range of the rotating mechanism is 0°~90°.

[0024] In the embodiments of this application, the top-view imaging device can be disposed above the rotating mechanism. The optical axis of the top-view imaging device is consistent with the rotation axis of the rotating mechanism. It is used to collect the planar position information of the target from above and has a large imaging field of view. It can be used for target position acquisition and rotation center fitting in the coarse positioning stage.

[0025] In the embodiments of this application, the target point set can be understood as the set of position coordinates of the target on the image plane acquired by the top-view imaging device at multiple rotation angles of the rotating mechanism, which is used to fit the rotation center.

[0026] In some embodiments of this application, the rotating mechanism carries the target and rotates it sequentially to multiple angular positions. At each angular position, the top-view imaging device captures the target from above, extracts the center position of the target using image processing algorithms (such as edge detection, contour fitting, or circle / point fitting), and records the pixel coordinates of the target on the image plane. Each rotation angle corresponds to a target position point, and the position points at all angles together constitute the target point set.

[0027] Step 102: Fit an initial rotation center based on the target point set, and control the planar motion platform to move the target to the initial rotation center; wherein, the planar motion platform represents the actuator used to move the target along two orthogonal directions in the plane.

[0028] In the embodiments of this application, the target center positioning device can control the rotating mechanism to rotate to multiple rotation angles, and after acquiring the planar position information of the target at multiple rotation angles through the top-view imaging device to obtain the target point set, fit an initial rotation center according to the target point set, and control the planar motion platform to move the target to the initial rotation center; wherein, the planar motion platform represents the execution mechanism for moving the target along two orthogonal directions in the plane.

[0029] In the embodiments of this application, the initial rotation center is an estimated position obtained by fitting the target point set using a fitting algorithm. Due to the limited accuracy of top-view imaging, this position is a preliminary estimate, and its accuracy is insufficient to meet the requirements of high-precision positioning, but it is sufficient to guide the target into the field of view of the microscopic imaging.

[0030] In some embodiments of this application, since each point in the target point set should theoretically be located on an arc centered at the rotation center, the most probable center position can be fitted from the target point set using a least-squares circle fitting algorithm, which serves as the initial rotation center. Specifically, during the fitting process, considering the different measurement error characteristics of each sampling point in the radial and tangential directions, a non-isotropic uncertainty model is used for weighted fitting to improve fitting accuracy.

[0031] In some embodiments of this application, after obtaining the initial rotation center, the planar motion platform is controlled to move the target along the first and second planar motion axes, moving the target from its current position to the initial rotation center position. This movement involves mapping, calibration, and transformation between the pixel coordinate system and the actual physical coordinate system. The goal of this step is to adjust the target to a position close to the rotation center, ensuring that the target does not exceed the limited field of view of high-magnification microscopy during subsequent microscopic imaging rotation operations.

[0032] In some embodiments of this application, when the target center positioning device fits an initial rotation center based on a set of target points, it can determine a first measurement uncertainty in the radial direction and a second measurement uncertainty in the tangential direction for each sampling point in the target point set; wherein the first measurement uncertainty is greater than the second measurement uncertainty; an isotropic uncertainty model is established based on the first and second measurement uncertainties; wherein the isotropic uncertainty model is used to characterize the characteristic that each sampling point has different measurement uncertainties in the radial and tangential directions; and the initial rotation center is obtained by weighted fitting of the target point set based on the isotropic uncertainty model.

[0033] In some embodiments of this application, the radial direction corresponds to the direction of the second planar motion axis, and the tangential direction corresponds to the direction of the first planar motion axis; in other words, the direction of the first planar motion axis is a high-precision axis direction, and the direction of the second planar motion axis is a low-precision axis direction.

[0034] It should be noted that, under conditions of small rotation angle, the displacement in the tangential direction is mainly reflected as the positional change caused by the change in angle, while the displacement in the radial direction is the result of the superposition of multiple error sources. The projection of the measurement noise component in the radial direction is more significant, so the radial error is greater than the tangential error.

[0035] In the embodiments of this application, under the condition of a small rotation angle, the positional errors of each sampling point in the target point set have different statistical characteristics in different directions. Tangential displacement is mainly caused by changes in the rotation angle, and its measurement uncertainty is relatively small; while radial displacement is the result of the superposition of multiple error sources (including measurement noise from the top-view imaging device, repetitive positioning errors of the rotating mechanism, extraction errors of the image processing algorithm, etc.). The projection of these errors in the radial direction is more significant, therefore the measurement uncertainty in the radial direction is greater than the measurement uncertainty in the tangential direction. In this embodiment, the radial uncertainty is approximately 1 pixel, and the tangential uncertainty is approximately 0.2 pixels.

[0036] In some embodiments of this application, traditional least-squares circle fitting typically assumes that the measurement errors at all sampling points follow an isotropic Gaussian distribution, meaning that the errors in all directions are equal. However, in the application scenario of this application, since the radial error is much larger than the tangential error, the isotropic assumption does not conform to reality. The anisotropic uncertainty model, by defining the radial and tangential covariance matrices separately for each sampling point, more accurately describes the anisotropic characteristics of the error distribution.

[0037] In the embodiments of this application, a weighted fitting of the target point set based on an isotropic uncertainty model is performed to obtain the initial rotation center. Specifically, during the fitting process, different weights are assigned according to the isotropic uncertainty model of each sampling point: sampling points with larger radial uncertainty are given smaller weights, and sampling points with smaller tangential uncertainty are given larger weights. Through weighted least squares fitting, the fitting result is made more inclined towards the direction with smaller confidence error, thereby improving the accuracy and robustness of the rotation center fitting. Compared with the traditional isotropic fitting method, this application can effectively suppress the interference of radial measurement noise on the fitting result and obtain a more accurate initial rotation center.

[0038] It should be noted that when the angle is limited (e.g., only 90°), only a short arc can be obtained, not a complete circle. For short arc fitting, radial error will seriously interfere with the calculation of the center (a slight change in the center does not significantly change the radius, but the point will shift tangentially). By using an isotropic uncertainty model to perform weighted fitting on the target point set, the fitting algorithm is essentially forced to "ignore" the radial jump of the points as much as possible, using high-precision "tangential" information to determine the curvature of the arc. This can greatly suppress the "center drift" phenomenon common in short arc fitting, making the center position of the coarse-aligned circle more accurate and reliable than the currently commonly used least-squares circle fitting.

[0039] In some embodiments of this application, when the target center positioning device controls the planar motion platform to move the target to the initial rotation center, it can respectively calibrate the mapping relationship between the first planar motion axis direction and the pixel coordinate system of the top-view imaging device, and the mapping relationship between the second planar motion axis direction and the pixel coordinate system of the top-view imaging device; according to the mapping relationship, the pixel difference between the position of the initial rotation center in the pixel coordinate system of the top-view imaging device and the current position of the target is converted into the actual movement distance of the planar motion platform; and the planar motion platform is controlled to move the target to the initial rotation center according to the actual movement distance.

[0040] It should be noted that the mechanical motion direction of the planar motion platform and the image pixel coordinate system of the top-view imaging device are not necessarily completely consistent, and the motion scale (i.e., the physical distance corresponding to a unit pixel) may differ in different directions. Therefore, calibration is required to determine the mapping relationship between the two. Specifically, the planar motion platform can be controlled to move a known physical distance along the first and second planar motion axes, respectively. Images before and after the movement can be acquired by the top-view imaging device, and the pixel displacement of the target position in the image can be calculated to establish a mapping matrix between the physical motion distance and the pixel displacement.

[0041] In some embodiments of this application, according to the mapping relationship, the pixel difference between the position of the initial rotation center in the pixel coordinate system of the top-view imaging device and the current position of the target is converted into the actual movement distance of the planar motion platform. That is, it can be understood as converting the pixel difference into the actual movement distance of the planar motion platform in the first planar motion axis direction and the second planar motion axis direction.

[0042] Furthermore, in some embodiments of this application, after the target center positioning device fits an initial rotation center based on the target point set and controls the planar motion platform to move the target to the initial rotation center, it can also collect the target's position information through a top-view imaging device to determine whether the target is located at the initial rotation center; if the target is not located at the initial rotation center, the process of controlling the planar motion platform to move the target to the initial rotation center is repeated until it is determined that the target is located at the initial rotation center.

[0043] Understandably, due to fitting errors, calibration errors, and motion errors, a single approach may not be sufficient to ensure the target accurately reaches the initial rotation center position. Therefore, after the control plane motion platform moves the target to the initial rotation center, the target's position information is acquired again via the top-view imaging device to determine if the target is indeed located at the initial rotation center. If the target is not located at the initial rotation center, the process of moving the target to the initial rotation center via the control plane motion platform is repeated (including recalculating the pixel difference, converting it to motion distance, and driving the motion) until the target is confirmed to be located at the initial rotation center. This iterative approach mechanism compensates for the accumulated errors in a single motion, ensuring that the target position during the coarse alignment stage is sufficiently close to the rotation center, thereby guaranteeing that the target remains within the field of view during subsequent microscopic imaging rotation focusing.

[0044] Step 103: Control the rotating mechanism to rotate to the first rotation angle, and use the microscopic imaging device to focus on the target axially, and determine the axial position when the focus is clear as the reference position of the imaging plane.

[0045] In the embodiments of this application, after the target center positioning device fits an initial rotation center according to the target point set and controls the planar motion platform to move the target to the initial rotation center, it controls the rotation mechanism to rotate to a first rotation angle, and uses a microscopic imaging device to perform axial focusing on the target, and determines the axial position when the focus is clear as the imaging plane reference position.

[0046] In the embodiments of this application, the microscopic imaging device is an imaging device disposed on the side of the rotating mechanism, used to perform high-precision imaging and axial focusing on the target after the target approaches the center of rotation. It has high magnification capability but limited field of view, and can be used for target clarity judgment and axial displacement measurement in the fine positioning stage.

[0047] In the embodiments of this application, the imaging plane reference position refers to the clear imaging position determined after axial focusing of the target by a microscopic imaging device at a first rotation angle. The imaging plane reference position can be used as a reference plane for subsequent axial displacement measurement.

[0048] It should be noted that when the first rotation angle is 0 degrees, the direction of the first planar motion axis of the planar motion platform is perpendicular to the axial direction of the microscopic imaging device.

[0049] In some embodiments of this application, the first rotation angle can be 0°; at this angle, the X-axis direction of the planar motion platform is perpendicular to the axial direction of the microscopic imaging device. The position of the microscopic imaging device is adjusted along its axial direction to achieve a clear image of the target. The axial position of the microscopic imaging device at this time is recorded as the imaging plane reference position, serving as a reference for subsequent axial displacement measurements.

[0050] Step 104: Keep the axial position of the microscopic imaging device unchanged while maintaining clear focus, control the rotating mechanism to rotate to the second rotation angle, and control the planar motion platform to move the target along the first planar motion axis until the target is clear again, so as to construct a constraint condition that the offset of the target in the second planar motion axis direction is equal to the offset in the first planar motion axis direction.

[0051] In the embodiments of this application, the target center positioning device can control the rotating mechanism to rotate to a first rotation angle, perform axial focusing on the target through the microscopic imaging device, determine the axial position when the focus is clear as the reference position of the imaging plane, keep the axial position of the microscopic imaging device unchanged when the focus is clear, control the rotating mechanism to rotate to a second rotation angle, and control the planar motion platform to move the target along the first planar motion axis until the target is in clear focus again, so as to construct a constraint condition that the offset of the target in the second planar motion axis direction is equal to the offset in the first planar motion axis direction; wherein, the first planar motion axis direction and the second planar motion axis direction are two orthogonal directions; the difference between the first rotation angle and the second rotation angle is 90 degrees.

[0052] In the embodiments of this application, a planar motion platform is used to carry a target and can move the target along two orthogonal directions in a plane. The two orthogonal directions are the first planar motion axis (X-axis) direction and the second planar motion axis (Y-axis) direction.

[0053] In the embodiments of this application, the constraint is a mathematical constraint constructed through specific geometric relationships at the second rotation angle, namely, "the offset of the target in the direction of the second planar motion axis is equal to the offset in the direction of the first planar motion axis." This constraint reduces the originally complex two-dimensional planar offset decoupling problem to a one-dimensional offset determination problem.

[0054] It should be noted that when the second rotation angle is 90 degrees, the direction of the first planar motion axis is parallel to the axial direction of the microscopic imaging device. This parallel relationship means that after rotating 90 degrees, the offset of the target in the direction of the second planar motion axis is converted into a defocusing amount in the axial direction. Therefore, this defocusing amount can be compensated by moving the target along the direction of the first planar motion axis, thus constructing a constraint condition of constant amplitude offset.

[0055] In the embodiments of this application, at the second rotation angle, the direction of the first planar motion axis cannot be orthogonal or perpendicular to the axial direction of the microscopic imaging device.

[0056] In the embodiments of this application, after performing step 103, the axial position of the microscopic imaging device is kept unchanged, and the rotating mechanism is rotated from a first rotation angle (e.g., 0°) to a second rotation angle (e.g., 90°). At the second rotation angle, the first planar motion axis of the planar motion platform is parallel to the axial direction of the microscopic imaging device. Since the target's original offset in the second planar motion axis direction is mapped to the axial direction after rotating 90°, the target deviates from the imaging plane reference position and becomes blurred. At this time, the planar motion platform is controlled to move the target only along the first planar motion axis direction, so that the target achieves a clear imaging state again. Since the axial position of the microscopic imaging device has not changed, the target becoming clear again means that the target's position in the axial direction has returned to the imaging plane reference position. Based on geometric relationships, it can be seen that the axial offset compensated by this operation is exactly equal to the target's offset in the second planar motion axis direction, and since the rotation angle is 90°, the target's offset in the second planar motion axis direction is equal to the offset in the first planar motion axis direction, thereby constructing an equal amplitude offset constraint condition.

[0057] Step 105: Control the rotating mechanism to rotate to the third rotation angle, adjust the microscopic imaging device along the axial direction of the microscopic imaging device until the target is in focus, and record the axial displacement of the microscopic imaging device relative to the reference position of the imaging plane; wherein, the maximum angle among the first rotation angle, the second rotation angle and the third rotation angle does not exceed 90 degrees.

[0058] In the embodiments of this application, the target center positioning device can keep the axial position of the microscopic imaging device unchanged while maintaining clear focus, control the rotating mechanism to rotate to the second rotation angle, and control the planar motion platform to move the target along the first planar motion axis until the target is clear again. After constructing the constraint condition that the offset of the target in the second planar motion axis direction is equal to the offset in the first planar motion axis direction, the rotating mechanism is controlled to rotate to the third rotation angle. When the microscopic imaging device is adjusted along the axial direction of the microscopic imaging device until the target is clear, the axial displacement of the microscopic imaging device relative to the reference position of the imaging plane is recorded. The maximum angle among the first rotation angle, the second rotation angle, and the third rotation angle does not exceed 90 degrees.

[0059] In the embodiments of this application, the axial displacement is the amount of displacement by which the microscopic imaging device moves along its axial direction at the third rotation angle to refocus the target. This displacement reflects the degree of defocusing of the target relative to the imaging plane reference position at the third rotation angle.

[0060] Step 106: Based on the axial displacement and constraint conditions, determine the offset of the target in the first plane motion axis direction and the second plane motion axis direction.

[0061] In the embodiments of this application, the target center positioning device can, after controlling the rotating mechanism to rotate to the third rotation angle and adjusting the microscopic imaging device along the axial direction of the microscopic imaging device until the target is in focus, record the axial displacement of the microscopic imaging device relative to the reference position of the imaging plane, and then determine the offset of the target in the first plane motion axis direction and the second plane motion axis direction based on the axial displacement and the constraint conditions.

[0062] It should be noted that the third rotation angle is greater than the minimum of the first and second rotation angles, and less than the maximum of the first and second rotation angles.

[0063] In some embodiments of this application, when the first rotation angle is 0° and the second rotation angle is 90°, the third rotation angle can be 45°.

[0064] In some embodiments of this application, when the target center positioning device determines the offset of the target in the first planar motion axis direction and the second planar motion axis direction based on the axial displacement and constraint conditions, it can obtain the first displacement of the target moving along the first planar motion axis direction at the second rotation angle; obtain the axial displacement of the microscopic imaging device moving along the axial direction of the microscopic imaging device at the third rotation angle; determine the offset of the target in the second planar motion axis direction based on the first rotation angle, the second rotation angle, the third rotation angle, the axial displacement, and the first displacement; and determine, based on the constraint conditions, that the offset of the target in the first planar motion axis direction is equal to the offset in the second planar motion axis direction.

[0065] In some embodiments of this application, when the target center positioning device determines the offset of the target in the direction of the second planar motion axis based on the first rotation angle, the second rotation angle, the third rotation angle, the axial displacement, and the first displacement, it can determine the first sine difference and the first cosine difference between the first rotation angle and the second rotation angle; determine the second sine difference and the second cosine difference between the third rotation angle and the second rotation angle; and determine the offset of the target in the direction of the second planar motion axis based on the first sine difference, the first cosine difference, the second sine difference, the second cosine difference, the axial displacement, and the first displacement.

[0066] For example, a specific method for determining the offset of the target in the direction of the second plane motion axis can be expressed as the following formula: (1); in, Indicates the axial displacement. Indicates the first displacement; , Indicates the second rotation angle. Indicates the third rotation angle; express (First sine difference); express (First cosine difference); express (Second sine difference); express (Second cosine difference); This represents the offset of the target in the direction of the motion axis of the second plane.

[0067] In some embodiments of this application, when the first rotation angle is 0 degrees, the second rotation angle is 90 degrees, and the third rotation angle is 45 degrees, the target center positioning device can determine the corresponding half-angle value based on the angle difference between the third rotation angle and the first rotation angle; and determine the offset of the target in the direction of the first planar motion axis based on the tangent of the sum of the half-angle value and the third rotation angle, as well as the axial displacement.

[0068] For example, when the first rotation angle is 0 degrees, the second rotation angle is 90 degrees, and the third rotation angle is 45 degrees, the corresponding half-angle value (22.5°) is determined based on the angle difference (45°) between the third rotation angle (45°) and the first rotation angle (0°); the tangent of the sum of the half-angle value and the third rotation angle is tan67.5°. When determining the offset of the target in the direction of the first plane motion axis, the above formula (1) can be simplified to = ×tan67.5°.

[0069] Furthermore, based on the constraint of constant amplitude offset, the offset of the target in the direction of the second surface motion axis... = .

[0070] Step 107: Control the planar motion platform to perform compensating motion according to the offset, so that the center of the target is aligned with the rotation center of the rotating mechanism.

[0071] In the embodiments of this application, after determining the offset of the target in the first planar motion axis direction and the second planar motion axis direction according to the axial displacement and constraint conditions, the target center positioning device can control the planar motion platform to perform compensating motion according to the offset, so as to align the center of the target with the rotation center of the rotating mechanism.

[0072] Based on the above embodiments, in another embodiment of this application, a high-precision positioning method for the rotation center under the condition of limited rotation angle is provided. The method achieves coarse centering of the rotation center through top-view imaging to ensure the feasibility of subsequent rotation and microscopic imaging operations. On this basis, the method uses microscopic imaging to construct a constraint condition that keeps the imaging plane unchanged. Combined with axial displacement measurement under a specific rotation angle, the in-plane offset of the target relative to the rotation center is analytically and quickly solved, thereby achieving high-precision positioning of the rotation center.

[0073] The high-precision positioning method for the rotation center under limited rotation angle conditions provided in this application is applied to scenarios where the target and the rotating mechanism are relatively fixed, and the rotation angle of the rotating mechanism is limited. The method mainly includes the following steps: S1: Multi-angle top-view imaging acquisition using rotating mechanism.

[0074] With the rotation angle of the rotating mechanism limited to a predetermined range, the planar position information of the target is acquired at multiple different rotation angle positions by the top-view imaging device, thereby obtaining the target point set corresponding to each rotation angle.

[0075] S2: Modeling of non-isotropic uncertainty and fitting of rotation center.

[0076] Uncertainty is constructed to address the different measurement error characteristics of each sampling point in the target point set in the radial and tangential directions. When the rotation angle is small, the tangential displacement mainly reflects the positional change caused by the angle change, while the radial displacement is the result of the superposition of multiple error sources. The projection of the equal components of measurement noise in the radial direction is more significant; therefore, the radial error is generally greater than the tangential error. An isotropic uncertainty model with a radial error threshold greater than the tangential error threshold is constructed for each sampling point. Based on this uncertainty model, a weighted fitting is performed on the target point set to improve the accuracy of the initial estimation of the rotation center's position. By modeling the uncertainty of each point, the inaccuracy of the sampling points caused by noise errors from the top-view imaging device and vibrations of the rotating stage is considered, thereby improving the accuracy of fitting the rotation center.

[0077] S3: XY axis motion calibration and approximation of the preliminary estimated rotation center.

[0078] Considering the angles between the X-axis (i.e., the first planar motion axis) and Y-axis (i.e., the second planar motion axis) of the actual motion platform and the horizontal and vertical directions of the imaging, it is necessary to calibrate the mapping relationship between the X-axis, Y-axis, and the imaging pixel coordinate system. By giving a certain known distance motion amplitude on the X-axis and Y-axis respectively, images at different positions are acquired by the top-view imaging device for mapping calculation, resulting in a mapping relationship matrix between image pixel distance and actual motion distance. Based on the difference between the obtained rotation center pixel coordinate position and the current pixel coordinate position, the mapping relationship is converted into the actual motion distance on the X-axis and Y-axis. The actual motion distance command is used to bring it close to the estimated position of the rotation center, and the measurement-motion compensation behavior is executed multiple times until the image acquired by the top-view imaging device indicates that the current position is basically consistent with the preliminary rotation center position. By comparing the actual axis motion with the imaging pixel motion, an accurate motion mapping relationship is constructed, achieving adaptability to different environments and scenes, while improving the pixel-physical space mapping accuracy and achieving high-precision positioning of the rotation center. By using the high-quality fitting of the rotation center by the top-view imaging device, the target is kept close to the rotation center, thus ensuring that the target does not exceed the field of view of the microscope imaging during subsequent rotation focusing.

[0079] S4: Establishment of the focal plane reference for microscopic imaging.

[0080] The rotating mechanism is rotated to a first rotation angle, at which the first planar motion axis of the target is kept perpendicular to the microscopic imaging axis. By adjusting the back-and-forth movement of the microscopic imaging device along its axis, the target achieves a clear image, and the relative distance along the microscopic imaging axis at this point is determined as the reference position of the imaging plane. By controlling the rotation mechanism to keep the first planar motion axis perpendicular to the microscopic imaging axis, it is ensured that the movement of the target along the first planar motion axis will not affect the focusing position of the imaging focusing plane.

[0081] S5: Construction of constant amplitude offset constraint.

[0082] Keeping the position of the microscopic imaging device unchanged, the rotating mechanism is rotated to a second rotation angle. At this rotation angle, the first planar motion axis remains parallel to the microscopic imaging axis. While maintaining the axial position of the microscopic imaging device, the target is moved only along the first planar motion axis until it returns to the reference position on the imaging plane. Since the first planar motion axis is perpendicular to the microscopic imaging axis at the first rotation angle, and the position of the microscopic imaging device remains unchanged, adjusting the movement of the first planar motion axis at the second rotation angle does not change the distance of the target relative to the microscopic imaging device at the first rotation angle. Moving the first planar motion axis ensures that both the first and second rotation angles are within the same imaging focal plane of the microscopic imaging device, thus creating a constraint condition that the magnitude of the target's offset in each orthogonal axis direction within the plane is equal. Secondary focusing is achieved through the movement of the first planar motion axis, ensuring that both rotation angles are at the same focal plane position and that the two rotation angles are perpendicular. This makes the offset of the first planar motion axis completely equal to the offset of the second planar motion axis, reducing the complex problem of two-axis offset to the problem of the influence of a single offset.

[0083] S6: Axial displacement measurement.

[0084] Rotate the rotating mechanism to the third rotation angle. While keeping the target plane position unchanged, adjust the position of the microscopic imaging device in the axial direction to make the target achieve a clear imaging state again, and record the axial displacement relative to the reference position of the imaging plane.

[0085] S7: Analytical calculation of plane offset and precise alignment.

[0086] Based on the relationship between the actual focused position of the target at the third rotation angle and the aforementioned reference distance to the microscopic imaging focusing plane, and combined with the constraint that the offsets of the two vertical axes are completely equal in step S5, the offset of the target in the plane is quickly and analytically solved. The calculated offset is used to control the target to perform compensating motion along the corresponding planar motion axis, achieving high-precision alignment of the rotation center.

[0087] Compared with existing methods, this application has at least the following advantages: it achieves coarse centering of the rotation center through top-view imaging, ensuring the feasibility of operation under conditions of limited rotation angle and limited field of view of microscopic imaging; based on coarse centering, it constructs geometric constraints with an invariant imaging plane through microscopic imaging, thereby establishing constraints on equal offsets of two orthogonal motion axes in the plane, reducing calculation parameters and improving the calculation efficiency of deviations of each axis; and it can achieve high-precision positioning of the rotation center under conditions of limited rotation angle without the need for large-angle rotation or complex optimization algorithms.

[0088] Furthermore, a long tube is selected to adsorb a spherical part as the target, and the rotation range of the rotating platform is 0° to 90°. The first planar motion axis is the forward and backward movement along the direction of the long tube, called the X-axis; the second planar motion axis is perpendicular to the direction of the long tube, called the Y-axis, as shown below. Figure 2 As shown. The first rotation angle is set to 0°, the second rotation angle to 90°, and the third rotation angle to 45°. The high-precision positioning method for the rotation center under limited rotation angle conditions may include the following steps: 1. Multiple rotation points are acquired through top-view imaging. Based on empirical values, the radial uncertainty is selected as 1 pixel and the tangential uncertainty as 0.2 pixels. The rotation center is then fitted, as shown below. Figure 3 As shown, a rotation center can be fitted based on multiple target center positions.

[0089] 2. Perform X and Y axis motion scale calibration. Control the X and Y axes to five different positions, acquire images, calculate pixel coordinates, and determine the mapping relationship between X and Y axis motion and pixel correspondence. Based on the mapping relationship, control the spherical part to move to the fitted rotation center.

[0090] Third, rotate to the 0° position. At this time, the X-axis is perpendicular to the microscopic axis. Move the axial displacement of the microscopic imaging device to make the target clear and reach the focal plane position.

[0091] 4. Keeping the microscope imaging device unchanged, rotate it to the 90° position and move the X-axis position to refocus it to achieve a clear state. At this point, both the 0° and 90° positions are at the focal plane of the microscope imaging device. This satisfies the constraint that the offsets of the X-axis and Y-axis relative to the center of rotation are completely equal.

[0092] 5. Rotate to the 45° position. Since the second step essentially reached the center of rotation, 45°, 0°, and 90° are all within the field of view of the microscopic imaging. At this point, since 0° and 90° are both at the focal plane, 45° lies on the vertical axis. If there is an offset in the X-axis or Y-axis, the 45° position is not yet in sharp focus. In this case, the axial displacement of the moving microscopic imaging device is used to obtain the movement distance. Based on the microscopic imaging movement distance, the X-axis and Y-axis offset information is quickly calculated, and the X-axis and Y-axis movements are controlled. Figure 4The diagram shown is a schematic diagram for solving the radial (Y-axis) offset.

[0093] VI. For example Figure 5 As shown, based on the angular relationship, it can be quickly determined that the X-axis offset is equal to the Y-axis offset, which is equal to tan67.5° and the 45° axial displacement of microscopic imaging. Motion compensation is performed based on this result to control the target to reach the rotation center, achieving a high-precision rotation center positioning method.

[0094] In summary, compared with existing technologies, this application has the following main advantages: By employing a two-step strategy of coarse and fine alignment, the feasibility of positioning is ensured under conditions of limited rotation angle and limited field of view in microscopic imaging. In the coarse alignment stage, the large field of view advantage of top-view imaging is utilized to fit the rotation center and guide the target to approach, ensuring that the target remains within the field of view during subsequent high-magnification microscopic imaging rotation. This overcomes the engineering problem of the target "running out of the frame" due to the small field of view in traditional methods. By constructing equal-amplitude offset constraints, the two-dimensional plane offset decoupling problem is reduced to a one-dimensional offset solution problem. Utilizing the geometric constraint that the two-axis offsets are equal at two vertical angles of 0° and 90°, the originally complex in-plane dual-axis coupled offset problem is transformed into a simple problem requiring only the measurement of one axial displacement, significantly reducing computational complexity, improving positioning efficiency, and eliminating the need for large-angle rotation or complex optimization algorithms. Through weighted fitting of an isotropic uncertainty model, the fitting accuracy of the initial rotation center in the coarse alignment stage is improved. Considering the actual physical characteristic that radial error is much larger than tangential error, a non-isotropic uncertainty model is established to perform weighted fitting on the target point set, effectively suppressing the interference of radial measurement noise on the fitting results and making the fitting results more accurate and reliable. High-precision alignment of the rotation center is achieved through automatic focusing and axial displacement measurement in microscopic imaging. In summary, this application provides a target center positioning method that balances positioning feasibility, positioning efficiency, and positioning accuracy under conditions of limited rotation angle and limited field of view in microscopic imaging, and has good engineering practical value.

[0095] Based on the above embodiments, another embodiment of this application provides a target center positioning device, such as... Figure 6 As shown, the target center positioning device 1 proposed in this application embodiment may include a processor 11 and a memory 12 storing instructions executable by the processor 11; further, the target center positioning device 1 may also include a communication interface 13 and a bus 14 for connecting the processor 11, the memory 12 and the communication interface 13.

[0096] In the embodiments of this application, the processor 11 can be at least one of the following: Application-Specific Integrated Circuit (ASIC), Digital Signal Processor (DSP), Digital Signal Processing Device (DSPD), Programmable Logic Device (PLD), Field Programmable Gate Array (FPGA), Central Processing Unit (CPU), controller, microcontroller, and microprocessor. It is understood that for different devices, the electronic device used to implement the above-mentioned processor function can also be other, and this application embodiment does not specifically limit it. The memory 12 can be connected to the processor 11, wherein the memory 12 is used to store executable program code, which includes computer operation instructions. The memory 12 may include high-speed RAM memory, and may also include non-volatile memory, such as at least two disk drives.

[0097] In embodiments of this application, bus 14 is used to connect communication interface 13, processor 11 and memory 12 to enable communication between these devices.

[0098] In embodiments of this application, memory 12 is used to store instructions and data.

[0099] In practical applications, the aforementioned memory 12 can be volatile memory, such as random-access memory (RAM), or non-volatile memory, such as read-only memory (ROM), flash memory, hard disk drive (HDD), or solid-state drive (SSD); or a combination of the above types of memory, and provide instructions and data to the processor 11.

[0100] Furthermore, in this embodiment, the functional modules can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional module.

[0101] If the integrated unit is implemented as a software functional module and is not sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this embodiment, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) or processor to execute all or part of the steps of the method of this embodiment.

[0102] Specifically, the program instructions corresponding to the target center positioning method and apparatus under a rotation angle-limited condition in this embodiment can be stored on a storage medium such as an optical disc or a hard disk. When the program instructions corresponding to the target center positioning method and apparatus under a rotation angle-limited condition in the storage medium are read or executed by a target center positioning device, the following steps are included: The rotating mechanism is controlled to rotate to multiple rotation angles, and the planar position information of the target at multiple rotation angles is acquired by the top-view imaging device to obtain the target point set; An initial rotation center is fitted based on the target point set, and the planar motion platform is controlled to move the target to the initial rotation center; wherein, the planar motion platform represents the actuator used to move the target along two orthogonal directions in the plane; Control the rotating mechanism to rotate to the first rotation angle, and use the microscopic imaging device to focus the target axially, and determine the axial position when the focus is clear as the reference position of the imaging plane. While maintaining a clear focus, the axial position of the microscopic imaging device remains unchanged. The rotating mechanism is controlled to rotate to a second rotation angle, and the planar motion platform is controlled to move the target along the first planar motion axis until the target is in focus again. This establishes a constraint condition that the offset of the target in the second planar motion axis direction is equal to the offset in the first planar motion axis direction. The first and second planar motion axis directions are two orthogonal directions. The difference between the first and second rotation angles is 90 degrees. Control the rotating mechanism to rotate to the third rotation angle, and adjust the microscopic imaging device along the axial direction of the microscopic imaging device until the target is in focus. Record the axial displacement of the microscopic imaging device relative to the reference position of the imaging plane; wherein the maximum angle among the first rotation angle, the second rotation angle, and the third rotation angle does not exceed 90 degrees. Based on the axial displacement and constraints, determine the offset of the target in the first plane motion axis direction and the second plane motion axis direction; The offset control planar motion platform performs compensating motion to align the center of the target with the rotation center of the rotating mechanism.

[0103] Based on the above embodiments, in another embodiment of this application, a target center positioning system is provided, such as... Figure 7 As shown, the target center positioning system 0 includes a target center positioning device 1, a rotation mechanism 2, a top-view imaging device 3, a planar motion platform 4, and a microscopic imaging device 5.

[0104] Rotating mechanism 2 is used to support the target and drive the target to rotate.

[0105] The top-view imaging device 3 is positioned above the rotating mechanism 2, and its optical axis is aligned with the rotation axis of the rotating mechanism 2. It is used to acquire planar position information of the target from above.

[0106] The microscopic imaging device 5 is located to the side of the rotating mechanism 2, and its optical axis is perpendicular to one of the two orthogonal motion directions of the planar motion platform 4. It is used to perform high-precision imaging and axial focusing on the target.

[0107] The planar motion platform 4 carries the target and is located on the rotating mechanism 2.

[0108] The target center positioning device 1 is communicatively connected to the rotating mechanism 2, the top-view imaging device 3, the planar motion platform 4, and the microscopic imaging device 5, respectively, and is used to execute the target center positioning method under the condition of limited rotation angle in the aforementioned embodiment, so as to control the rotating mechanism 2, the planar motion platform 4, the top-view imaging device 3, and the microscopic imaging device 5 to work together to achieve alignment between the center of the target and the rotation center of the rotating mechanism 2.

[0109] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of hardware embodiments, software embodiments, or embodiments combining software and hardware aspects. Furthermore, this application can take the form of a computer program product implemented on one or more computer-usable storage media (including, but not limited to, disk storage and optical storage) containing computer-usable program code.

[0110] This application is described with reference to schematic and / or block diagrams of implementations of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each step and / or block in the schematic and / or block diagrams, as well as combinations thereof, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in one or more steps of the schematic and / or one or more blocks of the block diagrams.

[0111] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in the implementation flow diagram. Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0112] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0113] The above embodiments are merely preferred embodiments provided to fully illustrate this application, and the scope of protection of this application is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on this application are all within the scope of protection of this application.

Claims

1. A method for locating the center of a target under conditions of limited rotation angle, characterized in that, The method includes: The rotating mechanism is controlled to rotate to multiple rotation angles, and the planar position information of the target under the multiple rotation angles is acquired by the top-view imaging device to obtain the target point set; An initial rotation center is fitted based on the target point set, and a planar motion platform is controlled to move the target to the initial rotation center; wherein, the planar motion platform represents an actuator for moving the target along two orthogonal directions in a plane; The rotating mechanism is controlled to rotate to the first rotation angle, and the target is axially focused by the microscopic imaging device. The axial position when the focus is clear is determined as the reference position of the imaging plane. While maintaining sharp focus, the axial position of the microscopic imaging device remains unchanged. The rotating mechanism is controlled to rotate to a second rotation angle, and the planar motion platform is controlled to move the target along the first planar motion axis until the target is sharp again. This establishes a constraint that the offset of the target in the second planar motion axis direction is equal to the offset in the first planar motion axis direction. The first and second planar motion axes are two orthogonal directions. The difference between the first and second rotation angles is 90 degrees. Control the rotating mechanism to rotate to the third rotation angle, and adjust the microscopic imaging device along the axial direction of the microscopic imaging device until the target is in focus. Record the axial displacement of the microscopic imaging device relative to the reference position of the imaging plane; wherein, the maximum angle among the first rotation angle, the second rotation angle, and the third rotation angle does not exceed 90 degrees. Based on the axial displacement and the constraint conditions, determine the offset of the target in the first planar motion axis direction and the second planar motion axis direction; The planar motion platform is controlled to perform compensating motion based on the offset, so that the center of the target is aligned with the rotation center of the rotating mechanism.

2. The target center positioning method under the condition of limited rotation angle according to claim 1, characterized in that, The step of fitting an initial rotation center based on the target point set includes: Determine the first measurement uncertainty in the radial direction and the second measurement uncertainty in the tangential direction for each sampling point in the target point set; wherein the first measurement uncertainty is greater than the second measurement uncertainty; An isotropic uncertainty model is established based on the first measurement uncertainty and the second measurement uncertainty; wherein, the isotropic uncertainty model is used to characterize the characteristic that each sampling point has different measurement uncertainties in the radial and tangential directions; The initial rotation center is obtained by weighted fitting of the target point set based on the aforementioned anisotropic uncertainty model.

3. The target center positioning method under the condition of limited rotation angle according to claim 1, characterized in that, The control plane motion platform moves the target to the initial rotation center, including: The mapping relationship between the first planar motion axis direction and the pixel coordinate system of the top-view imaging device, and the mapping relationship between the second planar motion axis direction and the pixel coordinate system of the top-view imaging device are respectively calibrated; Based on the mapping relationship, the pixel difference between the position of the initial rotation center in the pixel coordinate system of the top-view imaging device and the current position of the target is converted into the actual movement distance of the planar motion platform; Based on the actual movement distance, the planar motion platform is controlled to move the target to the initial rotation center.

4. The target center positioning method under the condition of limited rotation angle according to claim 1, characterized in that, After fitting an initial rotation center based on the target point set and controlling the planar motion platform to move the target to the initial rotation center, the method further includes: The top-view imaging device acquires the target's position information to determine whether the target is located at the initial rotation center; If the target is not located at the initial rotation center, the process of controlling the planar motion platform to move the target to the initial rotation center is repeated until it is determined that the target is located at the initial rotation center.

5. The target center positioning method under the condition of limited rotation angle according to claim 1, characterized in that, Determining the offset of the target in the first planar motion axis direction and the second planar motion axis direction based on the axial displacement and the constraint conditions includes: Obtain the first displacement of the target moving along the first planar motion axis at the second rotation angle; The offset of the target in the direction of the second planar motion axis is determined based on the first rotation angle, the second rotation angle, the third rotation angle, the axial displacement, and the first displacement. Based on the constraints, the offset of the target in the direction of the first planar motion axis is determined to be equal to the offset in the direction of the second planar motion axis.

6. The target center positioning method under the condition of limited rotation angle according to claim 5, characterized in that, Determining the offset of the target in the direction of the second planar motion axis based on the first rotation angle, the second rotation angle, the third rotation angle, the axial displacement, and the first displacement includes: Determine the first sine difference and the first cosine difference between the first rotation angle and the second rotation angle; Determine the second sine difference and the second cosine difference between the third rotation angle and the second rotation angle; The offset of the target in the direction of the second planar motion axis is determined based on the first sine difference, the first cosine difference, the second sine difference, the second cosine difference, the axial displacement, and the first displacement.

7. The target center positioning method under the condition of limited rotation angle according to claim 1, characterized in that, When the first rotation angle is 0 degrees, the direction of the first planar motion axis is perpendicular to the axial direction of the microscopic imaging device. When the second rotation angle is 90 degrees, the direction of the first planar motion axis is parallel to the axial direction of the microscopic imaging device.

8. A target center positioning device, characterized in that, The target center positioning device includes a processor and a memory storing processor-executable instructions; when the instructions are executed by the processor, the target center positioning method under the condition of limited rotation angle as described in any one of claims 1 to 7 is implemented.

9. A target center positioning system, characterized in that, include: The device comprises a rotating mechanism, a top-view imaging device, a planar motion platform, a microscopic imaging device, and a target center positioning device; the target center positioning device is used to perform the target center positioning method under the condition of limited rotation angle as described in any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the method as described in any one of claims 1 to 7.

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