Attitude measurement method for a target object

Abstract

This disclosure provides a method for measuring the attitude of a target object, comprising: in an initial state, the distance between the end of the central hole of the perforated corner cube prism and the PSD detector is h, and when the laser beam is incident normally, a calibration coordinate of a light spot is formed on the PSD detector, and the calibration coordinate of the two-dimensional motion platform is recorded; when the attitude of the target object changes, part of the laser beam passes through the central hole and illuminates the PSD detector, forming a new light spot; and determining whether the new light spot is at or near the center position of the PSD detector, if the new light spot is not at or near the center position of the PSD detector, driving the two-dimensional motion platform to move so that the new light spot approaches or near the center position of the PSD detector, recording the current coordinates of the light spot and the current coordinates of the two-dimensional motion platform; and obtaining the attitude of the target object.

Description

Technical Field

[0001] This disclosure relates to a method for measuring the attitude of a target object, belonging to the field of laser measurement. Background Technology

[0002] With the continuous development of my country's national economy and the continuous improvement of the level of modern manufacturing, fields such as aerospace, automobiles, ships, intelligent robots, and air-bearing simulators have increasingly higher requirements for attitude measurement in areas such as aircraft docking, automobile assembly, and industrial robot measurement and calibration.

[0003] Traditional attitude measurement methods mainly include inertial measurement, monocular vision measurement, mechanical positioning, and laser tracking measurement. These traditional methods are gradually failing to meet current attitude measurement needs in terms of measurement speed, range, accuracy, and efficiency.

[0004] Therefore, there is a need to provide a method for measuring the attitude of a target object to solve at least one of the above-mentioned technical problems. Summary of the Invention

[0005] To address one of the aforementioned technical problems, this disclosure provides a method for measuring the attitude of a target object.

[0006] According to one aspect of this disclosure, a method for measuring the attitude of a target object is provided, comprising:

[0007] The PSD detector is mounted on a two-dimensional motion platform, and the motion direction of the two-dimensional motion platform is parallel to the PSD detector.

[0008] A two-dimensional motion platform is mounted on the target object, and the two-dimensional motion platform changes its attitude as the target object changes its attitude.

[0009] An open-aperture corner cube prism is mounted on the target object, with the centerline of the open-aperture corner cube prism perpendicular to the PSD detector; wherein the open-aperture corner cube prism is obtained by having a central hole along the centerline of the corner cube prism, and the diameter of the central hole is smaller than the diameter of the laser beam;

[0010] In the initial state, the distance between the end of the central hole of the perforated corner cube prism and the PSD detector is h, and the calibration coordinates I of the light spot formed on the PSD detector when the laser beam is incident normally are... P (x P ,y P And record the calibration coordinates I of the two-dimensional motion platform. M (x M ,y M );

[0011] When the orientation of the target object changes, part of the laser beam shines through the central hole onto the PSD detector, forming a new light spot;

[0012] Determine if the new light spot is at or near the center of the PSD detector. If the new light spot is not at or near the center of the PSD detector, drive the 2D motion platform to move so that the new light spot approaches or near the center of the PSD detector, and record the current coordinates of the light spot. and the current coordinates of the two-dimensional motion platform as well as

[0013] The orientation of the target object is obtained based on the calibration coordinates of the light spot, the calibration coordinates of the two-dimensional motion platform, the current coordinates of the light spot, the current coordinates of the two-dimensional motion platform, and the distance h.

[0014] According to at least one embodiment of the target object attitude measurement method of the present disclosure, the attitude of the target object includes azimuth and pitch angle, wherein the azimuth angle is obtained by performing a moving average filter on the instantaneous azimuth angle at the current moment and the instantaneous azimuth angle at the previous N-1 moments; the pitch angle is obtained by performing a moving average filter on the instantaneous pitch angle at the current moment and the instantaneous pitch angle at the previous N-1 moments, wherein N is greater than or equal to 2.

[0015] A method for measuring the attitude of a target object according to at least one embodiment of the present disclosure.

[0016] The instantaneous azimuth angle as well as

[0017] The instantaneous pitch angle

[0018] According to at least one embodiment of the target object attitude measurement method of this disclosure, driving a two-dimensional motion platform to move such that a new light spot approaches or is near the center position of the PSD detector includes:

[0019] Given a central region S of a PSD detector, which is bounded by n boundary points, where the n boundary points are: Where n is greater than or equal to 3;

[0020] When the coordinates of the light spot on the PSD detector When outside the central region S, the cost function is used to traverse n boundary points and select the two points with the smallest Euclidean distance.

[0021] according to Fit the straight line l and calculate The projection point on line l The motion components in the two orthogonal stroke directions are obtained as follows

[0022] The motion components in two orthogonal stroke directions drive the two-dimensional motion platform to move, causing the PSD detector to translate and the laser beam to illuminate the central region of the PSD detector. Attached Figure Description

[0023] The accompanying drawings illustrate exemplary embodiments of the present disclosure and, together with the description thereof, serve to explain the principles of the present disclosure. These drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this specification.

[0024] Figure 1 This is a schematic diagram of the structure of a target object attitude measuring device according to one embodiment of the present disclosure.

[0025] Figure 2 This is a flowchart of a method for measuring the attitude of a target object according to one embodiment of the present disclosure.

[0026] The specific labels in the attached figures are as follows:

[0027] 100 Two-Dimensional Motion Platform

[0028] 200 PSD detector

[0029] 300° opening angle cone prism. Detailed Implementation

[0030] The present disclosure will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the disclosure. Furthermore, it should be noted that, for ease of description, only the parts relevant to the present disclosure are shown in the accompanying drawings.

[0031] It should be noted that, where there is no conflict, the embodiments and features described in this disclosure can be combined with each other. The technical solutions of this disclosure will now be described in detail with reference to the accompanying drawings and embodiments.

[0032] Unless otherwise stated, the exemplary implementations / embodiments shown are to be understood as providing exemplary features of various details that provide ways in which the technical concepts of this disclosure can be implemented in practice. Therefore, unless otherwise stated, the features of various implementations / embodiments may be additionally combined, separated, interchanged and / or rearranged without departing from the technical concepts of this disclosure.

[0033] The use of crosshairs and / or shading in the accompanying drawings is generally used to clarify the boundaries between adjacent components. Thus, unless otherwise stated, the presence or absence of crosshairs or shading does not convey or indicate any preference or requirement for the specific material, material properties, dimensions, proportions, commonalities between the illustrated components, or any other characteristics, properties, etc., of the components. Furthermore, in the accompanying drawings, the dimensions and relative dimensions of components may be exaggerated for clarity and / or descriptive purposes. When exemplary embodiments can be implemented differently, a specific process sequence may be performed in a different order than that described. For example, two consecutively described processes may be performed substantially simultaneously or in the reverse order of their description. Furthermore, the same reference numerals denote the same components.

[0034] When a component is referred to as being "on" or "above" another component, "connected to," or "joined to" another component, the component may be directly on, directly connected to, or directly joined to the other component, or there may be intermediate components. However, when a component is referred to as being "directly on" another component, "directly connected to," or "directly joined to" another component, there are no intermediate components. Therefore, the term "connection" can refer to a physical connection, an electrical connection, etc., and may or may not have intermediate components.

[0035] For descriptive purposes, this disclosure may use spatial relative terms such as “below,” “under,” “below,” “down,” “above,” “above,” “higher,” and “side (e.g., in a “sidewall”)” to describe the relationship between one component and another component as shown in the accompanying drawings. In addition to the orientations depicted in the drawings, the spatial relative terms are also intended to encompass different orientations of the device during use, operation, and / or manufacture. For example, if the device in the drawings is flipped, a component described as “below” or “under” another component or feature would subsequently be positioned “above” said other component or feature. Thus, the exemplary term “below” can encompass both “above” and “below” orientations. Furthermore, the device may be otherwise positioned (e.g., rotated 90 degrees or in other orientations), thus interpreting the spatial relative descriptive terms used herein accordingly.

[0036] The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting. As used herein, unless the context clearly indicates otherwise, the singular forms “a” and “the” are intended to include the plural forms as well. Furthermore, when the terms “comprising” and / or “including” and variations thereof are used in this specification, it indicates the presence of the stated features, integrals, steps, operations, parts, components, and / or groups thereof, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, parts, components, and / or groups thereof. It should also be noted that, as used herein, the terms “substantially,” “about,” and other similar terms are used as approximate terms rather than as terms of degree, thus explaining the inherent biases in measurements, calculated values, and / or provided values ​​that would be recognized by one of ordinary skill in the art.

[0037] Figure 1 This is a schematic diagram of the structure of a target object attitude measuring device according to one embodiment of the present disclosure. Figure 2 This is a flowchart of a method for measuring the attitude of a target object according to one embodiment of the present disclosure.

[0038] like Figure 1 and Figure 2 As shown, this disclosure provides a method for measuring the attitude of a target object, which is implemented through an attitude measuring device for the target object. The attitude measuring device includes a two-dimensional motion platform 100 and a PSD detector 200 mounted on the two-dimensional motion platform 100. In actual use, the two-dimensional motion platform 100 is mounted on the target object and its attitude changes with the attitude of the target object.

[0039] The attitude measurement device for the target object also includes an open-aperture corner cube prism 300, which is obtained by opening a central hole along the center line of the corner cube prism. The size of the central hole is small, for example, smaller than the diameter of the laser beam generated by the laser tracker. So when the laser beam generated by the laser tracker shines on the open-aperture corner cube prism from various angles, a portion of the laser beam can return to the laser tracker through an optical path parallel to the laser beam generated by the laser tracker, and a portion of the laser beam can shine on the PSD detector 200 through the central hole, forming a light spot on the PSD detector 200.

[0040] Therefore, in this disclosure, by opening a hole in the diagonal pyramid prism, the laser tracker can simultaneously track the target object and detect the target object's attitude, thus ensuring the accuracy of the laser tracking coordinate measurement and enabling the PSD detector 200 to operate normally.

[0041] Figure 1The perforated corner cube prism shown is only one possible implementation. The perforated corner cube prism of this disclosure can also be perforated only at the intersection of the center points of the corner cubes. The size of the perforation should ensure that the energy of the light returned by the perforated corner cube prism can enable the laser tracker to work normally.

[0042] In actual use, the perforated corner cone prism 300 is installed on the target object, and the central axis of the perforated corner cone prism 300 is perpendicular to the PSD detector 200, that is, perpendicular to the plane where the PSD detector 200 is located.

[0043] In a preferred embodiment, in the initial state, the central axis of the aperture corner prism 300 can pass through the central region of the PSD detector 200, and the distance between the end of the central hole of the aperture corner prism 300 and the PSD detector 200 is h, which remains unchanged.

[0044] In other words, the motion direction of the two-dimensional motion platform 100 is parallel to that of the PSD detector 200. At this time, the PSD detector 200 can only move within the plane in which it is located, so the distance h will not change.

[0045] In such Figure 2 As shown, the attitude measurement method for the target object disclosed herein may include:

[0046] A PSD detector is mounted on a two-dimensional motion platform, with the platform's motion direction parallel to the detector. The platform is then mounted on a target object, its attitude changing in response to the object's posture. An open-aperture corner cube prism is mounted on the target object, its centerline perpendicular to the PSD detector. The prism is formed by a central hole along its centerline, the diameter of which is smaller than the laser beam's diameter. Initially, the distance between the end of the prism's central hole and the PSD detector is h, and the calibration coordinates I of the laser beam forming a spot on the PSD detector when the laser beam is incident perpendicularly are... P (x P ,y P And record the calibration coordinates I of the two-dimensional motion platform. M (x M ,y MWhen the target object's posture changes, part of the laser beam shines through the central aperture onto the PSD detector, forming a new light spot. The system determines whether the new light spot is at or near the center of the PSD detector. If the new light spot is not at or near the center of the PSD detector, the system drives the two-dimensional motion platform to move, causing the new light spot to approach or near the center of the PSD detector, and records the current coordinates of the light spot. and the current coordinates of the two-dimensional motion platform The orientation of the target object is obtained based on the calibration coordinates of the light spot, the calibration coordinates of the two-dimensional motion platform, the current coordinates of the light spot, the current coordinates of the two-dimensional motion platform, and the distance h.

[0047] The following will provide a detailed description of the attitude measurement method for the target object disclosed herein.

[0048] In this disclosure, the PSD detector 200 and the two-dimensional motion platform 100 may use the same Cartesian coordinate system or different Cartesian coordinate systems. When the PSD detector 200 and the two-dimensional motion platform 100 use different Cartesian coordinate systems, it should be ensured that the positive directions of the two X-axis of the two Cartesian coordinate systems are the same, and the positive directions of the two Y-axis of the two Cartesian coordinate systems are also the same.

[0049] When the orientation of the target object changes, part of the laser beam shines through the central hole onto the PSD detector 200, forming a new light spot; in this disclosure, the new light spot is the light spot generated by the laser beam shining obliquely onto the PSD detector 200.

[0050] Since the central region of the PSD detector 200 is laser-sensitive, it is necessary to determine whether the new light spot is at or near the center of the PSD detector 200. If the new light spot is at or near the center of the PSD detector 200, the two-dimensional motion platform remains stationary, and only the current coordinates of the light spot are recorded. The current coordinates of the two-dimensional motion platform are the same as the calibrated coordinates, or the same as the coordinates of the two-dimensional motion platform at the previous moment.

[0051] In another scenario, when the new light spot is not at or near the center of the PSD detector 200, the two-dimensional motion platform 100 can be used to move the new light spot to the central region of the PSD detector, i.e., to or near the center of the PSD detector, and the current coordinates of the light spot can be recorded. and the current coordinates of the two-dimensional motion platform

[0052] In this disclosure, the current coordinates of the two-dimensional motion platform are not incremental values, but cumulative values, that is, the coordinates of the current position of the two-dimensional motion platform in the Cartesian coordinate system.

[0053] In a preferred embodiment, the calibration coordinates of the light spot, the calibration coordinates of the two-dimensional motion platform, the current coordinates of the light spot, the current coordinates of the two-dimensional motion platform, and the distance h can be used to obtain a matrix:

[0054]

[0055] In the formula, α represents the instantaneous azimuth angle, and β represents the instantaneous pitch angle.

[0056] Wherein: the instantaneous azimuth angle and the instantaneous pitch angle

[0057] More preferably, the attitude of the target object is obtained by performing a moving average filter on the instantaneous azimuth angle at the current moment and the instantaneous azimuth angle at the previous N-1 moments, and the pitch angle is obtained by performing a moving average filter on the instantaneous pitch angle at the current moment and the instantaneous pitch angle at the previous N-1 moments, thereby obtaining the attitude of the target object, where N is greater than or equal to 2.

[0058] In this disclosure, when a new light spot is not at or near the center of the PSD detector 200, the two-dimensional motion platform 100 needs to be driven to move as soon as possible, so that the new light spot approaches the center of the PSD detector, thereby enabling continuous measurement of the target object's attitude.

[0059] In one embodiment, driving the two-dimensional motion platform to move such that the new light spot approaches or is near the center of the PSD detector includes:

[0060] Given a central region S of a PSD detector, which is bounded by n boundary points, where the n boundary points are: Where n is greater than or equal to 3; that is, at least 3 boundary points are needed to define the central region S.

[0061] When the coordinates of the light spot on the PSD detector When outside the central region S, the cost function is used to traverse n boundary points and select the two points with the smallest Euclidean distance. As a preferred embodiment, the cost function

[0062] according to Fit the straight line l and calculate The projection point on line l The motion components in the two orthogonal stroke directions are obtained as follows

[0063] The two-dimensional motion platform 100 is driven to move according to the motion components in two orthogonal stroke directions, so that the PSD detector is translated and the laser beam is irradiated to the central region of the PSD detector.

[0064] Compared with existing technologies, the target object attitude measurement method of this disclosure mainly uses a PSD detector as the measuring device, which features fast calculation and high data output speed, facilitating improved data output rate when aligned with the laser tracker clock. Furthermore, this disclosure ensures that the light spot remains in the central region of the PSD detector through the movement of the two-dimensional motion platform 100, increasing the range of the PSD detector's measurement surface with good linearity, thereby expanding the angle measurement range.

[0065] Furthermore, the target object attitude measurement method disclosed herein can accurately measure the spot coordinate offset, thus achieving high angular measurement accuracy. The measurement results of the target object attitude measurement method disclosed herein are based on the measurement laser coordinate system, facilitating unification with the global coordinate system of the laser tracker.

[0066] In the description of this specification, the references to terms such as "one embodiment / mode," "some embodiments / modes," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment / mode or example is included in at least one embodiment / mode or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment / mode or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments / modes or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments / modes or examples described in this specification, as well as the features of different embodiments / modes or examples.

[0067] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0068] Those skilled in the art should understand that the above embodiments are merely for illustrating the present disclosure and are not intended to limit the scope of the disclosure. Those skilled in the art can make other changes or modifications based on the above disclosure, and these changes or modifications still fall within the scope of the present disclosure.

Claims

1. A method for measuring the attitude of a target object, characterized in that, include: The PSD detector is mounted on a two-dimensional motion platform, and the motion direction of the two-dimensional motion platform is parallel to the PSD detector. A two-dimensional motion platform is mounted on the target object, and the two-dimensional motion platform changes its attitude as the target object changes its attitude. An open-aperture corner cube prism is mounted on the target object, with the centerline of the open-aperture corner cube prism perpendicular to the PSD detector; wherein the open-aperture corner cube prism is obtained by having a central hole along the centerline of the corner cube prism, and the diameter of the central hole is smaller than the diameter of the laser beam; In the initial state, the distance between the end of the central hole of the perforated corner cube prism and the PSD detector is h, and the calibration coordinates I of the light spot formed on the PSD detector when the laser beam is incident normally are... P (x P ,y P And record the calibration coordinates I of the two-dimensional motion platform. M (x M ,y M ); When the target object's posture changes, part of the laser beam shines through the central aperture onto the PSD detector, forming a new light spot; and Determine if the new light spot is at or near the center of the PSD detector. If the new light spot is not at or near the center of the PSD detector, drive the 2D motion platform to move so that the new light spot approaches or near the center of the PSD detector, and record the current coordinates of the light spot. and the current coordinates of the two-dimensional motion platform The orientation of the target object is obtained based on the calibration coordinates of the light spot, the calibration coordinates of the two-dimensional motion platform, the current coordinates of the light spot, the current coordinates of the two-dimensional motion platform, and the distance h.

2. The method for measuring the attitude of a target object as described in claim 1, characterized in that, The attitude of the target object includes azimuth and pitch angles. The azimuth angle is obtained by performing a moving average filter on the instantaneous azimuth angle at the current moment and the instantaneous azimuth angles at the previous N-1 moments. The pitch angle is obtained by performing a moving average filter on the instantaneous pitch angle at the current moment and the instantaneous pitch angles at the previous N-1 moments, where N is greater than or equal to 2.

3. The method for measuring the attitude of a target object as described in claim 2, characterized in that, The instantaneous azimuth angle as well as The instantaneous pitch angle 4. The method for measuring the attitude of a target object as described in claim 1, characterized in that, Driving the two-dimensional motion platform to move so that the new light spot approaches or is near the center of the PSD detector includes: Given a central region S of a PSD detector, which is bounded by n boundary points, where the n boundary points are: Where n is greater than or equal to 3; When the coordinates of the light spot on the PSD detector When outside the central region S, the cost function is used to traverse n boundary points and select the two points with the smallest Euclidean distance. according to Fit the straight line l and calculate The projection point on line l The motion components in the two orthogonal stroke directions are obtained as follows The motion components in two orthogonal stroke directions drive the two-dimensional motion platform to move, causing the PSD detector to translate and the laser beam to illuminate the central region of the PSD detector.

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