Cylindrical workpiece automatic alignment scanning system and method

Abstract

The application provides a kind of cylindrical workpiece automatic alignment scanning system and method.The system includes: by up and down telescopic mechanism and horizontal rotating mechanism composition scanning device, fixed on the rotating arm of scanning device by multiple laser range finder composition detection device and scanning equipment, located below scanning device omnidirectional mobile mobile platform, placed on the cylindrical workpiece of mobile platform, with laser range finder data communication platform controller;Laser range finder is used to measure the distance from its cylindrical workpiece side, platform controller is used to calculate the position deviation of the center axis of cylindrical workpiece and the center axis of horizontal rotating mechanism based on the distance value measured by multiple laser range finder, and eliminate the deviation by controlling mobile platform to move and make two center axes align.The detection device for alignment of the application only needs several laser range finders, with the advantages of low cost of hardware equipment, simple control method, high alignment accuracy, etc.

Description

Technical Field

[0001] This invention belongs to the field of automatic control technology, specifically relating to an automatic alignment and scanning system and method for cylindrical workpieces. Background Technology

[0002] Currently, flaw detection scanning is becoming increasingly widespread. For example, CT or DR scanning equipment is used to perform flaw detection scanning on objects to be inspected. In some application scenarios, flaw detection scanning requires the scanning equipment to rotate horizontally around the object being inspected, demanding that the rotation center axis of the scanning equipment be precisely aligned or coincident with the center axis of the object. Traditional alignment methods typically involve placing the object to be inspected on a horizontally movable platform and achieving alignment by manually or automatically moving the platform. Traditional alignment methods are time-consuming and labor-intensive, and the required alignment accuracy is often difficult to meet.

[0003] Therefore, this invention proposes an automatic alignment and scanning system and method for cylindrical workpieces. Summary of the Invention

[0004] To address the aforementioned problems in the prior art, this invention provides an automatic alignment and scanning system and method for cylindrical workpieces.

[0005] To achieve the above objectives, the present invention adopts the following technical solution.

[0006] In a first aspect, the present invention provides an automatic alignment and scanning system for a cylindrical workpiece, comprising: a scanning device consisting of an upper and lower telescopic mechanism and a horizontal rotation mechanism; a detection device and a scanning device consisting of multiple laser rangefinders fixed on the rotating arm of the scanning device; a mobile platform located below the scanning device and capable of omnidirectional movement; a cylindrical workpiece placed on the mobile platform; and a platform controller for data communication with the laser rangefinders; the laser rangefinders are used to measure the distance between themselves and the side of the cylindrical workpiece; the platform controller is used to calculate the positional deviation between the central axis of the cylindrical workpiece and the rotational central axis of the horizontal rotation mechanism based on the distance values ​​measured by the multiple laser rangefinders, and to eliminate the deviation by controlling the movement of the mobile platform to align the two central axes.

[0007] Furthermore, the detection device includes a first laser rangefinder, a second laser rangefinder, and a third laser rangefinder that are horizontally collinear and equally spaced. The three laser rangefinders emit three horizontal parallel laser beams toward the side of the cylindrical workpiece. The laser beam emitted by the second laser rangefinder passes through the rotation center of the horizontal rotation mechanism. The second laser rangefinder is located directly below the scanning device.

[0008] Furthermore, the method to align the two central axes includes: establishing a Cartesian coordinate system, with the y-axis parallel to the line where the three laser rangefinders are located, the direction from the third laser rangefinder to the first laser rangefinder being the positive direction of the y-axis, and rotating the y-axis 90° clockwise to obtain the x-axis.

[0009] Further, the method for aligning the two central axes includes:

[0010] The platform controller obtains the distance values l1, l0, and l2 output by the first laser rangefinder, the second laser rangefinder, and the third laser rangefinder;

[0011] The platform controller controls the mobile platform to move along the x-axis and / or y-axis according to the magnitudes of l1, l0, and l2, so that l1 = l2 and l0 = R - r, where R and r are the radii of the scanning circle of the scanning mechanism and the cylindrical cross-section radius of the workpiece, respectively.

[0012] Further, the control of the mobile platform to move along the x-axis and / or y-axis so that l1 = l2 and l0 = R - r specifically includes:

[0013] If l1 > l2, the mobile platform is moved in the positive y-axis direction by Δy so that l1 = l2, where Δy > 0;

[0014] If l1 < l2, the mobile platform is moved in the negative y-axis direction by Δy so that l1 = l2, where Δy > 0;

[0015] If l1 = l2 and l0 > R - r, the mobile platform is moved in the negative x-axis direction by Δx so that l1 = l2 and l0 = R - r, where Δx > 0;

[0016] If l1 = l2 and l0 < R - r, the mobile platform is moved in the positive x-axis direction by Δx so that l1 = l2 and l0 = R - r, where Δx > 0.

[0017] Further, Δy is solved by the following formula:

[0018]

[0019] In the formula, L is the distance between the first laser rangefinder and the third laser rangefinder.

[0020] Further, Δx = |R - r - l0|.

[0021] Further, 0 < L ≤ 2r, and the alignment accuracy is the highest when L = 2r.

[0022] In a second aspect, the present invention provides a method for alignment using the system, including the following steps:

[0023] By controlling the mobile platform, the workpiece is moved under the scanning device and is approximately aligned with the rotating mechanism in the vertical direction;

[0024] Obtain the distances between the laser rangefinders and the side surface of the cylindrical workpiece measured by multiple laser rangefinders;

[0025] Calculate the positional deviation between the central axis of the cylindrical workpiece and the rotation central axis of the scanning device based on multiple distance values;

[0026] Eliminate the deviation by controlling the movement of the moving platform to align the two central axes.

[0027] Further, the detection device includes a first laser rangefinder, a second laser rangefinder, and a third laser rangefinder that are horizontally collinear and equally spaced. The three laser rangefinders emit three horizontal parallel laser beams towards the side of the cylindrical workpiece. The laser beam emitted by the second laser rangefinder passes through the rotation center of the horizontal rotation mechanism; the second laser rangefinder is located directly below the scanning device.

[0028] Furthermore, the method for aligning the two central axes includes: establishing a plane rectangular coordinate system, where the y-axis is parallel to the line where the three laser rangefinders are located, and the direction from the third laser rangefinder to the first laser rangefinder is the positive direction of the y-axis. The x-axis is obtained by rotating the y-axis clockwise by 90°.

[0029] Furthermore, the method for aligning the two central axes includes:

[0030] The platform controller obtains the distance values l1, l0, and l2 output by the first laser rangefinder, the second laser rangefinder, and the third laser rangefinder;

[0031] The platform controller controls the movement of the moving platform along the x-axis and / or y-axis directions according to the magnitudes of l1, l0, and l2, so that l1 = l2 and l0 = R - r, where R and r are the radius of the scanning circumference of the scanning mechanism and the radius of the cylindrical cross-section of the workpiece, respectively.

[0032] Furthermore, the control of the movement of the moving platform along the x-axis and / or y-axis directions to make l1 = l2 and l0 = R - r specifically includes:

[0033] If l1 > l2, move the moving platform along the positive y-axis by Δy to make l1 = l2, where Δy > 0;

[0034] If l1 < l2, move the moving platform along the negative y-axis by Δy to make l1 = l2, where Δy > 0;

[0035] If l1 = l2 and l0 > R - r, move the moving platform along the negative x-axis by Δx to make l1 = l2 and l0 = R - r, where Δx > 0;

[0036] If l1 = l2 and l0 < R - r, move the moving platform along the positive x-axis by Δx to make l1 = l2 and l0 = R - r, where Δx > 0.

[0037] Furthermore, Δy is solved according to the following formula:

[0038]

[0039] In the formula, L is the distance between the first laser rangefinder and the third laser rangefinder.

[0040] Furthermore, Δx = |R - r - l0|.

[0041] Furthermore, 0 < L ≤ 2r. When L = 2r, the alignment accuracy is the highest.

[0042] Compared with the prior art, the present invention has the following beneficial effects.

[0043] The present invention realizes the automatic alignment of a cylindrical workpiece by providing a scanning device composed of an up-and-down telescopic mechanism and a horizontal rotation mechanism, a detection device composed of multiple laser rangefinders fixed on the rotating arm of the scanning device and a scanning device, a mobile platform capable of omnidirectional movement located below the scanning device, a cylindrical workpiece placed on the mobile platform, a platform controller for data communication with the laser rangefinders. The laser rangefinders are used to measure the distance between them and the side surface of the cylindrical workpiece. The platform controller is used to calculate the position deviation between the central axis of the cylindrical workpiece and the rotation center axis of the rotation mechanism based on the distance values measured by multiple laser rangefinders, and eliminate the deviation by controlling the movement of the mobile platform to align the two central axes. The detection device for alignment in the present invention only requires several (generally 3) laser rangefinders, and has the advantages of low hardware equipment cost, simple control method, and high alignment accuracy. Description of the Drawings

[0044] Figure 1 It is a schematic diagram of an automatic alignment scanning system for a cylindrical workpiece according to an embodiment of the present invention. Figure 2 It is a schematic diagram of the geometric relationship for automatic alignment.

[0045] Figure 3 It is a schematic diagram of the geometric relationship for calculating Δy when l1 < l2.

[0046] Figure 4 It is a flowchart of a method for alignment using the system according to an embodiment of the present invention.

[0047] In the figure: 1 - up-and-down telescopic mechanism, 2 - horizontal rotation mechanism, 3 - rotating arm, 4 - scanning device, 5 - detection device, 51 - first laser rangefinder, 52 - second laser rangefinder, 53 - third laser rangefinder, 6 - workpiece, 7 - mobile platform. Detailed Embodiments

[0048] To make the objectives, technical solutions, and advantages of this invention clearer and more understandable, the invention will be further described below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0049] Figure 1 This is a block diagram of an automatic alignment and scanning system for a cylindrical workpiece according to an embodiment of the present invention. The system includes: a scanning device consisting of a vertical telescopic mechanism 1 and a horizontal rotation mechanism 2; a detection device 5 consisting of multiple laser rangefinders and a scanning device 4 fixed on the rotating arm 3 of the scanning device; a moving platform 7 located below the scanning device and capable of omnidirectional movement; a cylindrical workpiece 6 placed on the moving platform 7; and a platform controller that communicates with the laser rangefinders. The laser rangefinders are used to measure the distance between themselves and the side of the cylindrical workpiece 6. The platform controller is used to calculate the positional deviation between the central axis of the cylindrical workpiece 6 and the rotational central axis of the horizontal rotation mechanism 2 based on the distance values ​​measured by the multiple laser rangefinders, and to eliminate the deviation by controlling the movement of the moving platform 7 to align the two central axes.

[0050] In this embodiment, the system mainly consists of a scanning device, a detection device 5, a scanning equipment 4, a moving platform 7, a workpiece 6, and a platform controller. Figure 1 (Not shown in the diagram) The following section describes the functional principles of each part.

[0051] The scanning device is used to drive the scanning equipment 4 to perform circumferential scanning around the workpiece 6. The scanning device includes an up-and-down telescopic mechanism 1 and a horizontal rotation mechanism 2. The up-and-down telescopic mechanism 1 is used to adjust the scanning equipment 4 to a suitable height (corresponding to the workpiece 6 to be scanned); the horizontal rotation mechanism 2 is used to drive the scanning equipment 4 to rotate around the workpiece 6 in a horizontal plane, and of course, it also drives the inspection device to rotate.

[0052] The detection device 5, together with the scanning device 4, is fixed on the rotating arm 3 of the horizontal rotating mechanism 2 (in a very close position) and is used to detect the deviation between the rotation center axis of the horizontal rotating mechanism 2 and the center axis of the cylindrical workpiece 6. When the scanning device 4 scans around the cylindrical workpiece 6, to ensure that the distance between the scanning device 4 and the side of the workpiece 6 remains equal, the two center axes must be perfectly aligned, meaning that the circular cross-section of the workpiece 6 and the scanning circumference of the scanning device 4 are concentric circles. In this embodiment, the detection device 5 consists of multiple laser rangefinders. These rangefinders emit laser signals to the side of the workpiece 6 and receive the reflected laser echo signals, measuring the distance to the side of the cylindrical workpiece 6 based on the time delay between the emitted and echo signals. Based on the distance values ​​measured by the multiple laser rangefinders at different positions, the positional deviation between the two center axes can be calculated.

[0053] Scanning device 4 is used to perform flaw detection scanning on workpiece 6. Scanning device 4 can be a CT (computed tomography) device or a DR (digital radiography) device.

[0054] Workpiece 6 is the object to be detected (or scanned). In this embodiment, the shape of workpiece 6 is defined as cylindrical, therefore the relevant algorithms in the alignment strategy are based on the cylindrical workpiece 6.

[0055] The platform controller is mainly used to control the movement of the mobile platform 7 carrying the workpiece 6 in a two-dimensional plane (horizontal plane). The platform controller also communicates with multiple laser rangefinders to calculate the positional deviation of the two central axes based on the distance values ​​measured by the multiple laser rangefinders at different positions, and outputs control signals to make the mobile platform 7 move the workpiece 6 in the direction to eliminate the deviation, thereby aligning the two central axes.

[0056] The detection device 5 used for alignment in this embodiment only requires a few laser rangefinders, and has the advantages of low hardware cost, simple control method and high alignment accuracy.

[0057] As an optional embodiment, the detection device 5 includes a first laser rangefinder 51, a second laser rangefinder 52, and a third laser rangefinder 53, which are horizontally collinear and equally spaced. The three laser rangefinders emit three horizontal parallel laser beams toward the side of the cylindrical workpiece 6. The laser beam emitted by the second laser rangefinder 52 passes through the rotation center of the horizontal rotation mechanism 2. The second laser rangefinder 52 is located directly below the scanning device 4.

[0058] This embodiment provides a specific technical solution for the detection device 5. The detection device 5 in this embodiment consists of three laser rangefinders: a first laser rangefinder 51, a second laser rangefinder 52, and a third laser rangefinder 53. For example... Figure 1 , 2 As shown, three laser rangefinders are horizontally collinear and equidistant, with the second laser rangefinder 52 located directly below the scanning device 4. The three laser rangefinders emit three horizontal parallel laser beams towards the side of the cylindrical workpiece 6, with the laser beam emitted by the second laser rangefinder 52 passing precisely through the rotation center of the horizontal rotating mechanism 2. This arrangement of the relative positions of the three laser rangefinders and the scanning device 4 simplifies the calculation of the deviation between the two central axes.

[0059] As an optional embodiment, the method for aligning the two central axes includes: establishing a plane rectangular coordinate system, with the y-axis parallel to the straight line where the three laser rangefinders are located, the direction from the third laser rangefinder 53 to the first laser rangefinder 51 being the positive direction of the y-axis, and rotating the y-axis 90° clockwise to obtain the x-axis.

[0060] This embodiment provides a method for establishing a plane rectangular coordinate system. Since the alignment operation in this embodiment only needs to change the position of the central axis of the workpiece 6 by changing the position of the moving platform 7 on the horizontal plane, this embodiment only needs to establish a plane rectangular coordinate system on the horizontal plane. The y-axis is parallel to the straight line where the three laser rangefinders are located, and the positive direction of the y-axis is the direction from the third laser rangefinder 53 to the first laser rangefinder 51; the x-axis is obtained by rotating the y-axis clockwise by 900, as Figure 2 shown. The origin position of the plane rectangular coordinate system is not limited and can be set according to specific circumstances.

[0061] As an optional embodiment, the method for aligning two central axes includes:

[0062] The platform controller obtains the distance values l1, l0, and l2 output by the first laser rangefinder 51, the second laser rangefinder 52, and the third laser rangefinder 53;

[0063] The platform controller controls the movement of the moving platform 7 along the x-axis and / or y-axis directions according to the magnitudes of l1, l0, and l2, so that l1 = l2 and l0 = R - r, where R and r are the radii of the scanning circumference of the scanning mechanism and the cylindrical cross-section radius of the workpiece 6, respectively.

[0064] This embodiment provides a technical solution for aligning two central axes. The platform controller first obtains the distances l1, l0, and l2 between the three laser rangefinders and the side surface of the cylindrical workpiece 6. When the two central axes are aligned, Figure 2 the two circles in Figure 2 are concentric, and l1, l0, and l2 satisfy l1 = l2 and l0 = R - r, where R and r are the radii of the two circles in

[0065] As an optional embodiment, the control of the movement of the moving platform 7 along the x-axis and / or y-axis directions to make l1 = l2 and l0 = R - r specifically includes:

[0066] If l1 > l2, move the moving platform 7 in the positive y-axis direction by Δy to make l1 = l2, where Δy > 0;

[0067] If l1 < l2, move the moving platform 7 in the negative y-axis direction by Δy to make l1 = l2, where Δy > 0;

[0068] If l1 = l2 and l0 > R - r, move the moving platform 7 in the negative x-axis direction by Δx to make l1 = l2 and l0 = R - r, where Δx > 0;

[0069] If \(l1 = l2\) and \(l0 < R - r\), move the mobile platform 7 in the positive x-axis direction by \(\Delta x\) to make \(l1 = l2\) and \(l0 = R - r\), where \(\Delta x>0\).

[0070] This embodiment provides a specific method for controlling the movement of the mobile platform 7. The adjustment method of this embodiment is divided into two steps: First, adjust the position of the mobile platform 7 along the y-axis to make \(l1 = l2\). Specifically, if \(l1>l2\), move the mobile platform 7 in the positive y-axis direction by \(\Delta y\); conversely, move the mobile platform 7 in the negative y-axis direction by \(\Delta y\). Then, adjust the position of the mobile platform 7 along the x-axis to make \(l0 = R - r\) and keep \(l1 = l2\) unchanged. Specifically, if \(l0>R - r\), move the mobile platform 7 in the positive x-axis direction by \(\Delta x\); conversely, move the mobile platform 7 in the negative x-axis direction by \(\Delta x\). The values of \(\Delta x\) and \(\Delta y\) are determined by \(l0\), \(l1\), \(l2\), \(R\), \(r\) and the distances between the laser rangefinders. Specific solution methods for them will be given in the following embodiments respectively.

[0071] As an optional embodiment, \(\Delta y\) is solved according to the following formula:

[0072]

[0073] In the formula, \(L\) is the distance between the first laser rangefinder 51 and the third laser rangefinder 53.

[0074] This embodiment provides a solution method for \(\Delta y\). Figure 3 A schematic diagram of the geometric relationship for calculating \(\Delta y\) when \(l1 < l2\) is given. By solving the two right triangles with \(r\) as the hypotenuse in the figure, expressions of the two horizontal right sides represented by \(\Delta y\) are obtained respectively, and the difference between them is the absolute value of \(l1 - l2\). Since \(\Delta y>0\) is set, the above equation containing the absolute value is suitable for both cases of \(l1 < l2\) and \(l1>l2\). The method of solving a quadratic equation of one variable can be used to solve \(\Delta y\), or the iterative method can also be used to solve \(\Delta y\).

[0075] As an optional embodiment, \(\Delta x=\vert R - r - l0\vert\).

[0076] This embodiment provides a solution method for \(\Delta x\). \(\Delta x\) is when \(l1 = l2\), \(l0>R - r\) or \(l0 < R - r\), after moving the mobile platform 7 along the x-axis by \(\Delta x\), make \(l0 = R - r\). The geometric relationship for solving \(\Delta x\) is very simple, so no schematic diagram is drawn. \(\Delta x\) only needs to take the difference between \(R - r\) and \(l0\). Since \(\Delta x>0\) is set, the difference between \(R - r\) and \(l0\) after taking the absolute value is suitable for both cases of \(l0>R - r\) and \(l0 < R - r\).

[0077] As an optional embodiment, \(0 < L\leq2r\), and when \(L = 2r\), the alignment accuracy is the highest.

[0078] This embodiment gives the value range of the distance between the laser rangefinders. As Figure 2 , 3 As shown, the distance between the first laser rangefinder 51 and the third laser rangefinder 53 is L, or the distance between the two laser rangefinders is L / 2. To ensure that all three laser rangefinders can simultaneously measure the distance or that the emitted lasers can hit the side of the workpiece 6, L ≤ 2r must be ensured. Based on the equation for solving Δy, we can obtain:

[0079]

[0080] According to the above formula, the larger r is, the larger the error and the lower the accuracy; the larger L is, the smaller the error and the higher the accuracy. Alignment accuracy can be improved by increasing the spacing of the laser rangefinder. When L = 2r, dy / dL = 0, and the alignment accuracy is the highest.

[0081] Figure 4 A method for alignment using the system according to an embodiment of the present invention includes the following steps:

[0082] Step 101: By controlling the moving platform 7, the workpiece 6 is moved below the scanning device and roughly aligned with the rotating mechanism in the vertical direction;

[0083] Step 102: Obtain the distances between the laser rangefinders and the side of the cylindrical workpiece 6 as measured by multiple laser rangefinders;

[0084] Step 103: Calculate the positional deviation between the central axis of the cylindrical workpiece 6 and the rotation center axis of the scanning device based on multiple distance values;

[0085] Step 104: Eliminate the deviation by controlling the movement of the mobile platform 7 to align the two central axes.

[0086] The method in this embodiment is similar to... Figure 1 The implementation principle and technical effect of the system embodiments shown are similar to those of the embodiments described above, and will not be repeated here. The same applies to the subsequent embodiments, which will not be described in detail.

[0087] As an optional embodiment, the detection device 5 includes a first laser rangefinder 51, a second laser rangefinder 52, and a third laser rangefinder 53, which are horizontally collinear and equally spaced. The three laser rangefinders emit three horizontal parallel laser beams toward the side of the cylindrical workpiece 6. The laser beam emitted by the second laser rangefinder 52 passes through the rotation center of the horizontal rotation mechanism 2. The second laser rangefinder 52 is located directly below the scanning device 4.

[0088] As an optional embodiment, the method for aligning the two central axes includes: establishing a plane rectangular coordinate system, with the y-axis parallel to the line where the three laser rangefinders are located, the direction from the third laser rangefinder 53 to the first laser rangefinder 51 being the positive direction of the y-axis, and rotating the y-axis clockwise by 90° to obtain the x-axis.

[0089] As an optional embodiment, the method for aligning two central axes includes:

[0090] The platform controller obtains the distance values l1, l0, and l2 output by the first laser rangefinder 51, the second laser rangefinder 52, and the third laser rangefinder 53;

[0091] The platform controller controls the mobile platform 7 to move along the x-axis and / or y-axis directions according to the magnitudes of l1, l0, and l2, so that l1 = l2 and l0 = R - r, where R and r are the radii of the scanning circumference of the scanning mechanism and the cylindrical cross-sectional radius of the workpiece 6, respectively.

[0092] As an optional embodiment, the control of the mobile platform 7 to move along the x-axis and / or y-axis directions so that l1 = l2 and l0 = R - r specifically includes:

[0093] If l1 > l2, the mobile platform 7 is moved in the positive y-axis direction by Δy to make l1 = l2, where Δy > 0;

[0094] If l1 < l2, the mobile platform 7 is moved in the negative y-axis direction by Δy to make l1 = l2, where Δy > 0;

[0095] If l1 = l2 and l0 > R - r, the mobile platform 7 is moved in the negative x-axis direction by Δx to make l1 = l2 and l0 = R - r, where Δx > 0;

[0096] If l1 = l2 and l0 < R - r, the mobile platform 7 is moved in the positive x-axis direction by Δx to make l1 = l2 and l0 = R - r, where Δx > 0.

[0097] As an optional embodiment, Δy is solved according to the following formula: [[ID=2L]]

[0098]

[0099] In the formula, L is the distance between the first laser rangefinder 51 and the third laser rangefinder 53.

[0100] As an optional embodiment, Δx = |R - r - l0|.

[0101] As an optional embodiment, 0 < L ≤ 2r, and the alignment accuracy is the highest when L = 2r.

[0102] As described above, the above are only the specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. An automatic alignment and scanning system for cylindrical workpieces, characterized in that, Comprising: A scanning device composed of an up-and-down telescopic mechanism and a horizontal rotation mechanism, a detection device fixed on the rotating arm of the scanning device and composed of multiple laser rangefinders and a scanning device, a mobile platform that can move omnidirectionally under the scanning device, a cylindrical workpiece placed on the mobile platform, and a platform controller for data communication with the laser rangefinders; the laser rangefinders are used to measure the distance between them and the side surface of the cylindrical workpiece, and the platform controller is used to calculate the position deviation between the central axis of the cylindrical workpiece and the rotation central axis of the horizontal rotation mechanism based on the distance values measured by the multiple laser rangefinders, and eliminate the deviation by controlling the movement of the mobile platform to align the two central axes. The detection device includes a first laser rangefinder, a second laser rangefinder, and a third laser rangefinder that are horizontally collinear and equally spaced. The three laser rangefinders emit three horizontal parallel laser beams to the side surface of the cylindrical workpiece, and the laser beam emitted by the second laser rangefinder passes through the rotation center of the horizontal rotation mechanism; the second laser rangefinder is located directly below the scanning device.

2. The automatic alignment and scanning system for cylindrical workpieces according to claim 1, characterized in that, The method for aligning the two central axes includes: establishing a plane rectangular coordinate system, with the y-axis parallel to the line where the three laser rangefinders are located, and the direction from the third laser rangefinder to the first laser rangefinder as the positive direction of the y-axis, and the x-axis is obtained by rotating the y-axis clockwise by 90°.

3. The automatic alignment and scanning system for cylindrical workpieces according to claim 2, characterized in that, The method for aligning the two central axes includes: The platform controller obtains the distance values l1, l0, and l2 output by the first laser rangefinder, the second laser rangefinder, and the third laser rangefinder; The platform controller controls the movement of the mobile platform along the x-axis and / or y-axis directions according to the magnitudes of l1, l0, and l2, so that l1 = l2 and l0 = R - r, where R and r are the radius of the scanning circumference of the scanning mechanism and the radius of the cylindrical cross-section of the workpiece, respectively.

4. The automatic alignment and scanning system for cylindrical workpieces according to claim 3, characterized in that, The control of the movement of the mobile platform along the x-axis and / or y-axis directions to make l1 = l2 and l0 = R - r specifically includes: If l1 > l2, the mobile platform is moved along the positive y-axis by Δy to make l1 = l2, where Δy > 0; If l1 < l2, the mobile platform is moved along the negative y-axis by Δy to make l1 = l2, where Δy > 0; If l1 = l2 and l0 > R - r, the mobile platform is moved along the negative x-axis by Δx to make l1 = l2 and l0 = R - r, where Δx > 0; If l1 = l2 and l0 < R - r, the mobile platform is moved along the positive x-axis by Δx to make l1 = l2 and l0 = R - r, where Δx > 0.

5. The automatic alignment and scanning system for cylindrical workpieces according to claim 4, characterized in that, The Δy is solved by the following formula: In the formula, L is the distance between the first laser rangefinder and the third laser rangefinder.

6. The automatic alignment and scanning system for cylindrical workpieces according to claim 5, characterized in that, The .

7. The automatic alignment and scanning system for cylindrical workpieces according to claim 6, characterized in that, 0 < L ≤ 2r, and when L = 2r, the alignment accuracy is the highest.

8. A method for alignment using the system according to any one of claims 1 to 7, characterized in that, Including the following steps: By controlling the mobile platform, the workpiece is moved under the scanning device and roughly aligned with the rotation mechanism in the vertical direction; Obtain the distances between the laser rangefinders and the side surface of the cylindrical workpiece measured by the multiple laser rangefinders; Calculate the position deviation between the central axis of the cylindrical workpiece and the rotation central axis of the scanning device based on the multiple distance values; Eliminate the deviation by controlling the movement of the mobile platform to align the two central axes.

9. The method according to claim 8, characterized in that, The method for aligning the two central axes includes: The platform controller acquires the distance values ​​l1, l0, and l2 output by the first laser rangefinder, the second laser rangefinder, and the third laser rangefinder; The platform controller controls the moving platform to move along the x-axis and / or y-axis based on the values ​​of l1, l0, and l2, so that l1=l2, l0=Rr, where R and r are the radius of the scanning circle of the scanning mechanism and the radius of the cylindrical cross-section of the workpiece, respectively.

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