Pipe curvature online measuring device and method based on continuum mechanism

Abstract

The invention provides a tubular product curvature online measuring device and method based on a continuum mechanism, belongs to the field of tubular product detection, and solves the technical problem of how to detect tubular product bending data in the machining process. The measuring device comprises a motion platform, a continuum mechanism and a displacement measuring mechanism. The continuum mechanism is provided with a pipe passing hole, can be bent along with the shape of a pipe, and comprises a termination disc, a spacing disc, a base disc, a telescopic structure bone, a fixed structure bone and a reset spring; the base disc is installed on the motion platform, the at least one spacing disc is arranged between the termination disc and the base disc, the reset spring is arranged between any two adjacent discs, the two ends of the fixed structure bone are connected to the termination disc and the base disc, the middle of the fixed structure bone penetrates through the spacing disc, and one end of the telescopic structure bone is connected to the termination disc, sequentially penetrates through the spacing disc and the base disc and finally is connected with the displacement measuring mechanism. The displacement measuring mechanism can detect the displacement amount of the telescopic structure bone to estimate bending data. The device can detect the curvature of the pipe on line, and solves the problem that detection can only be carried out after processing.

Description

Technical Field

[0001] The present invention relates to the technical field of pipe detection, and in particular to an online pipe curvature measurement device and method based on a continuum mechanism. Background Art

[0002] Complex-shaped pipes are crucial for applications in high-tech industries and cutting-edge fields such as aerospace, shipbuilding, nuclear energy, petrochemicals, automotive, and engineering machinery. Traditional pipe bending processes, while simple in shape, have significant limitations when it comes to bending complex spatial curves. To overcome this bottleneck, the free-form pipe bender emerged. Through kinematic control of a single die, the free-form pipe bender can precisely produce the desired complex curved pipe shape, eliminating the need for frequent die changes to achieve the desired shape. This overcomes the shortcomings of traditional pipe benders.

[0003] However, free-bending tube bending machines also have limitations. Due to the physical properties of the material, the tube shape may fluctuate during the bending process, significantly affecting the final bending result. For example, springback in metal materials is a problem that must be addressed. In actual processing, springback calculation methods are often required to fine-tune the bending process to compensate for springback deviations. Furthermore, specialized measuring equipment is required to evaluate the bending accuracy of the entire bent tube product.

[0004] Currently, a variety of pipe and profile inspection technologies are available on the market. These measuring devices can be categorized as contact or non-contact, depending on whether they come into contact with the workpiece being inspected. However, these measuring devices share several common limitations: First, they are expensive to inspect; second, they can only be used offline, meaning that the product must be inspected after the process is complete. This means that the measurement results of existing measuring equipment can only be used to make preliminary adjustments to the next bending process, and cannot be used to control the product processing in real time during the current bending process, making it impossible to detect and correct deviations in the process in a timely manner. These measurement limitations severely restrict the actual production efficiency of free-form pipe bending machines, reduce the flexibility and responsiveness of the production process, and affect the stability of product quality. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the present invention proposes an online measurement device and method for pipe curvature based on a continuum mechanism to solve the technical problem in the existing technology that the current detection technology on the market can only detect the product after the processing process is completed, but cannot be detected online.

[0006] The technical solution adopted by the present invention is an online measurement device and method for pipe curvature based on a continuum mechanism.

[0007] Among them, an online measurement device for pipe curvature based on a continuum mechanism includes a motion platform, a continuum mechanism and a displacement measurement mechanism;

[0008] A pipe passage hole is provided in the middle of the motion platform;

[0009] The continuum mechanism is also provided with a pipe passage hole and can be bent and deformed according to the shape of the inserted pipe. The continuum mechanism includes a termination plate, a spacer plate, a base plate, a telescopic structural bone, a fixed structural bone and a return spring.

[0010] The base plate is fixedly installed on the motion platform and the pipes between them are aligned through holes. At least one spacer plate is arranged between the termination plate and the base plate. Multiple reset springs are respectively arranged between any two adjacent plates. The two ends of the fixed structural bone are respectively connected to the termination plate and the base plate, and the middle part passes through the spacer plate. At least three telescopic structural bones are arranged in an equidistant circular array. After one end of each telescopic structural bone is connected to the termination plate, it slides through the spacer plate and the base plate in turn, and is finally connected to the displacement measuring mechanism. The displacement measuring mechanism can detect the displacement of the telescopic structural bone.

[0011] Optionally, the displacement measuring mechanism and the sliding end of the telescopic structural bone are connected through a reversing link, one end of the reversing link is hinged to the sliding end of the telescopic structural bone, and the other end is connected to the displacement measuring mechanism, and the displacement measuring mechanism is located on the periphery of the motion platform.

[0012] Optionally, the displacement measuring mechanism includes a slider, a linear displacement measuring unit and a guide rail, the guide rail is arranged on the motion platform and faces the center of the motion platform, the slider is slidably arranged in the guide rail and is hinged to the reversing link, and the linear displacement measuring unit can detect the sliding amount of the slider.

[0013] Optionally, the linear displacement measuring unit is a slider-type displacement sensor, or a wire-type sensor, or a laser triangulation sensor, or a grating sensor.

[0014] Optionally, when the linear displacement measuring unit uses a grating sensor, it includes a grating scale arranged on the guide rail and a grating detection head fixedly installed on the slider, and the grating detection head faces the grating scale.

[0015] Optionally, the telescopic structural bone and / or the fixed structural bone is rod-shaped and made of an alloy material with superelastic properties.

[0016] Optionally, a guide flange is further included, which is opposite to the base plate and installed at the entrance end of the hole through which the pipe passes.

[0017] Optionally, the opposing surfaces of the adjacent terminating disc and the spacer disc, the spacer disc and the spacer disc, and the spacer disc and the base disc are respectively provided with bosses, and the bosses are clamped into the inner rings at both ends of the reset spring.

[0018] Optionally, a motion mechanism is further included, the motion platform is installed at the motion end of the motion mechanism, the inner hole of the base plate is provided with a bending structure, and when the motion platform moves, the bending structure bends the pipe introduced therein.

[0019] Among them, a method for online measurement of pipe curvature based on a continuum mechanism, using the above-mentioned online measurement device for pipe curvature based on a continuum mechanism, comprises the following steps:

[0020] The bent pipe passes through the pipe hole at the center of the motion platform and passes through the pipe hole of the continuum mechanism;

[0021] The outer periphery of the tube contacts the inner cavity of the continuum structure and causes the continuum structure to deform, and each of the telescopic structural bones deforms accordingly, and the sliding end undergoes sliding displacement. The displacement is detected by the displacement measuring mechanism and is used to calculate the bending angle and bending direction angle of the tube;

[0022] After the tube leaves the continuum structure, the continuum structure recovers its shape.

[0023] It can be seen from the above technical solution that the beneficial technical effects of the present invention are as follows:

[0024] This system can detect pipe curvature online, resolving the existing problem of only being able to detect pipe curvature after processing. By integrating a motion platform and a continuum mechanism, the continuum deforms as the pipe passes through it. A displacement measurement mechanism detects the displacement of the telescopic structure and calculates the pipe curvature data. This online detection method provides timely feedback, facilitating rapid process adjustments, improving production efficiency and product quality, and reducing defective product rates. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly describes the drawings required for the specific embodiments or the description of the prior art. Similar elements or parts are generally identified by similar reference numerals throughout the drawings. Elements or parts in the drawings are not necessarily drawn to scale.

[0026] Figure 1 This is an overall schematic diagram of the non-bending state measuring device of the present invention;

[0027] Figure 2 Schematic diagram of the overall structure of the bending state measuring device of the present invention;

[0028] Figure 3 Schematic diagram of the continuum mechanism of the present invention in a non-bent state;

[0029] Figure 4 Schematic diagram of the continuum mechanism in a bent state according to the present invention;

[0030] Figure 5 Schematic diagram of the reversing mechanism of the present invention;

[0031] Figure 6 Schematic diagram of the displacement measurement mechanism of the present invention;

[0032] Figure 7 This is a schematic diagram of the displacement measuring mechanism of the present invention from another perspective;

[0033] Figure 8 This is a schematic diagram of the continuum mechanism disc of the present invention;

[0034] Figure 9 This is a schematic diagram of geometric information when the continuum mechanism of the present invention is bent;

[0035] Figure 10 This is a schematic diagram of the projection direction of a disk of the continuum mechanism of the present invention;

[0036] Figure 11 This is a schematic diagram of the geometric information of the reversing connecting rod of the continuum mechanism of the present invention.

[0037] Figure numerals: pipe 1, continuum mechanism 2, reversing link 3, displacement measuring mechanism 4, motion platform 5, termination plate 2a, spacer plate 2b, telescopic structural bone 2c, fixed structural bone 2d, return spring 2e, base plate 2f, guide flange 2g, boss 2aa, grating scale 4a, slider 4b. DETAILED DESCRIPTION

[0038] The following embodiments of the technical solution of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention and are therefore only examples and are not intended to limit the scope of protection of the present invention.

[0039] It should be noted that, unless otherwise specified, the technical or scientific terms used in this application should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0040] This embodiment provides an online measurement device for pipe curvature based on a continuum mechanism, wherein a possible implementation method is as follows: Figure 1The device includes a motion platform 5, a continuum mechanism 2 and a displacement measuring mechanism 4; a pipe passing hole is provided in the middle of the motion platform 5; the continuum mechanism 2 is also provided with a pipe passing hole and the continuum mechanism 2 can follow the shape of the inserted pipe 1 and bend and deform. To ensure that the pipe passes through the continuum mechanism smoothly, the diameter of the through hole at the center of the disc is just enough to accommodate pipes of equal diameter. Figure 3 , including a termination disk 2a, a spacer disk 2b, a base disk 2f, a telescopic structural bone 2c, a fixed structural bone 2d and a reset spring 2e; the base disk 2f is fixedly installed on the motion platform 5 and the pipes between each other are aligned through holes, at least one spacer disk 2b is arranged between the termination disk 2a and the base disk 2f. As a preferred embodiment, two spacer disks 2b can be set, and multiple reset springs 2e are respectively arranged between any two adjacent disks to provide support and restoring forces for the interaction between adjacent disks. The two ends of the fixed structural bone 2d are respectively fixedly connected to the termination disk 2a and the base disk 2f, and the middle part passes through the spacer disk 2b. A through hole corresponding to the fixed structural bone 2d but with a diameter larger than the fixed structural bone 2d can be set on the spacer disk 2b. At least three telescopic structural bones 2c are arranged in an equidistant circular array, preferably three, with an array angular spacing of 120 degrees. After one end of each telescopic structural bone 2c is fixedly connected to the terminal plate 2a, it slides through the spacer plate 2b and the base plate 2f in turn. Small holes with apertures matching the diameter of the telescopic structural bone 2c can be set at corresponding positions on the spacer plate 2b and the base plate 2f so that the two can slide relative to each other. The telescopic structural bone 2c is finally connected to the displacement measuring mechanism 4, which can detect the displacement of the telescopic structural bone 2c.

[0041] The principle of the measurement device in the above embodiment is briefly described as follows: This device is installed at the exit of the tube bending mechanism, or the bending die is directly fixedly connected to the base plate 2f. The bent tube is directly inserted into the tube passage hole of the continuum mechanism 2. After being bent by the bending die, the tube continues to pass through the tube passage holes of several spacer plates. During this process, each plate contacts the outer surface of the tube, is perpendicular to the tube axis, and is spaced along the tube axis. The continuum mechanism envelops and follows the local bending shape of the tube, causing each structural bone to bend. The fixed structural bone 2d maintains the stability of the continuum mechanism by being fixed at both ends and its own constant length, ensuring that the continuum mechanism envelops the local bending shape of the tube. The movable ends of the multiple telescopic structural bones 2c undergo linear displacement along the axial direction of the movable ends of the telescopic structural bones 2c, and the amount of displacement is detected by the displacement measurement mechanism 4. The linear displacement and geometric relationship of the ends of each telescopic structural bone 2c can be used to obtain shape information of the continuum mechanism, ultimately inferring and completing the local shape description of the bent tube.

[0042] The above-mentioned online pipe curvature measurement device based on a continuum mechanism has significant benefits. Installed at the exit of a pipe bending mechanism or connected to a bending die, it can measure pipe curvature in real time during processing, overcoming the limitation of existing technologies that only allow post-processing measurement. The continuum mechanism 2 bends and deforms with the pipe 1, while the displacement measurement mechanism 4 detects the displacement of the telescopic structure rib 2c. Based on geometric relationships, the local shape of the pipe is inferred, achieving precise online measurement of pipe curvature, facilitating timely process adjustments and improving product quality.

[0043] For this example, please refer to Figure 5 The displacement measuring mechanism 4 and the sliding end of the telescopic structure bone 2c are connected through a reversing link 3. One end of the reversing link 3 is hinged to the sliding end of the telescopic structure bone 2c, and the other end is connected to the displacement measuring mechanism 4. The displacement measuring mechanism 4 is located on the periphery of the motion platform 5.

[0044] The beneficial effect of the above embodiment lies in that the reversing link 3 in this embodiment cleverly connects the displacement measuring mechanism 4 to the sliding end of the telescopic structural bone 2c, allowing the displacement measuring mechanism 4 to be rationally positioned on the periphery of the motion platform 5. This design cleverly frees up the inlet end of the continuum mechanism 2, namely the middle area at the rear end of the motion platform 5, allowing this area to be smoothly connected to a free-flowing pipe bender or other equipment, facilitating the coordinated operation of the device with the pipe bender or other equipment, and enhancing the device's applicability and flexibility.

[0045] Furthermore, the displacement measuring mechanism 4 includes a slider 4b, a linear displacement measuring unit and a guide rail. The guide rail is arranged on the motion platform 5 and faces the center of the motion platform 5. The guide rail can be grooved on the motion platform 5 to accommodate the slider sliding along it. The slider 4b is slidably arranged in the guide rail and the bottom is hinged to the reversing link 3. The linear displacement measuring unit can detect the sliding amount of the slider 4b.

[0046] The solution of the above embodiment has remarkable benefits. By utilizing the reversing action of the reversing link 3, the vertical sliding of the distal end of the telescopic structural member 2c at the center rear end of the tubular motion platform 5 is cleverly converted into planar sliding of the slider 4b along the periphery of the motion platform 5. This conversion greatly facilitates the installation of the detection device, allowing it to be easily adapted to the tubular outlet of the tubular bending machine, thus enabling smooth online detection of tubular curvature and effectively improving detection efficiency and practicality.

[0047] As a further solution to the above embodiments, in this embodiment, the linear displacement measuring unit may be a slider 4b-type displacement sensor, a wire-type sensor, a laser triangulation sensor, a grating sensor, or the like. It should be noted that the above list is not exhaustive, but merely some possible implementations. For the purposes of this solution, any method capable of detecting the displacement of the slider 4b is optional and interchangeable for the displacement measuring unit.

[0048] Furthermore, when the linear displacement measurement unit uses a grating sensor solution, it includes a grating scale 4a set on the guide rail and a grating detection head fixedly installed on the slider 4b. The grating detection head faces the grating scale 4a. During the sliding of the slider 4b, the grating detection head also slides relative to the grating scale 4a. The grating detection head can detect the sliding amount, thereby judging the sliding amount of the slider 4b, thereby inferring the sliding amount of the sliding end of the telescopic structure bone 2c, thereby inferring the bending shape of the continuum mechanism 2, that is, the bending shape of the steel pipe. The grating measurement principle is based on the Moire fringe phenomenon to achieve high-precision displacement detection. The grating scale 4a is engraved with precise equidistant lines, and the grating detection head is fixed to the slider 4b and faces the grating scale 4a. When the slider 4b slides, the grating detection head and the grating scale 4a move relative to each other, and the two grating lines are superimposed to form Moire fringes. The number of shifted stripes is precisely proportional to the displacement of slider 4b. By detecting these shifts, the grating sensor head can accurately determine the amount of slider 4b's movement, and thus infer the displacement of the sliding end of telescopic structure rib 2c and the bending shape of continuum mechanism 2. This has significant benefits. The grating sensor solution offers high measurement accuracy, enabling precise acquisition of tube bending information and providing a reliable basis for quality control in tube processing.

[0049] In this embodiment, the telescopic structural bone 2c and / or the fixed structural bone 2d are rod-shaped and made of an alloy material with superelastic properties. The superelastic rod can generate approximately no axial strain under axial load conditions, so that the bending of the telescopic structural bone 2c is manifested as the telescopic displacement of the end along the axial direction of the tube. The displacement is collected and used to calculate the bending parameters of the tube, which can improve the measurement accuracy. The fixed structural bone can maintain the stability and deformation resilience of the continuum structure through the characteristics of being fixed at both ends and its own constant length. The telescopic structural bone can accurately reflect the degree of bending through the sliding of the other end through the characteristics of being fixed at one end and its own constant length. Alloy materials with superelastic properties, such as Nitinol (NiTi) alloy, can withstand large recoverable strains due to reversible phase transformation; for example, Ti-Al-Cr alloy has high specific strength and superelasticity at room temperature. The above examples of superelastic materials are only for better illustrating the technical content of this solution, and are not limitations on the implementation methods of this solution;

[0050] Please combine this embodiment with Figure 1-Figure 4, also includes a guide flange 2g, which is opposite to the base plate 2f and is installed at the entrance end of the hole through which the pipe passes, and plays a guiding role for the inserted pipe. It also includes a motion mechanism, a motion platform 5 is installed at the motion end of the motion mechanism, and a bending structure is provided in the inner hole of the base plate 2f. When the motion platform 5 moves, the bending structure bends and forms the pipe 1 passed through. Simply put, the motion platform 5 and the motion mechanism are installed at the outlet end of the pipe feeder, and the pipe feeder inserts the pipe into the guide flange 2g and the base plate 2f at a fixed angle. The motion mechanism can move in space relative to the pipe feeder, so that the bending structure of the inner hole of the base plate 2f bends and deforms the pipe, and then sends it to the continuum mechanism 2 for measurement of the bending angle and bending direction angle. The guide flange 2g is installed at the entrance end of the hole through which the pipe passes, providing guidance for the insertion of the pipe, and ensuring that the pipe accurately enters the subsequent structure. The motion platform 5 is installed at the motion end of the motion mechanism, and cooperates with the inner hole bending structure of the base plate 2f. It can bend the pipe at the outlet end of the pipe feeder as the motion mechanism moves in space, and can quickly send the bent pipe to the continuum mechanism 2 for measurement, realizing the integration of bending and measurement and improving efficiency.

[0051] For this example, please refer to Figure 8 Bosses 2aa are provided on the opposing surfaces of adjacent terminating discs 2a and spacer discs 2b, adjacent spacer discs 2b and 2b, and adjacent spacer discs 2b and base disc 2f. Bosses 2aa engage the inner rings of the two ends of the return spring 2e. This structure effectively ensures the stable installation of the return spring 2e, preventing it from shifting or falling off during operation. It also ensures a stable and reliable restoring force between adjacent discs, thereby ensuring that the continuum mechanism 2 properly and accurately follows the bending deformation of the pipe, thereby improving measurement accuracy.

[0052] This embodiment is an embodiment of a method for online measurement of pipe curvature based on a continuum mechanism, using the above-mentioned online measurement device for pipe curvature 1 based on a continuum mechanism 2, and includes the following steps:

[0053] The bent pipe 1 passes through the pipe hole at the center of the motion platform 5 and passes through the pipe hole of the continuum mechanism 2;

[0054] The outer periphery of the tube 1 contacts the inner cavity of the continuum structure 2, causing the continuum structure 2 to deform. Each telescopic structural bone 2c deforms accordingly, and the sliding end undergoes sliding displacement. The displacement is detected by the displacement measurement mechanism 4 and is used to calculate the bending angle and bending direction of the tube 1.

[0055] After the tube 1 leaves the continuum structure 2, the continuum structure 2 recovers its shape.

[0056] The above-described measurement method has significant benefits. It enables real-time detection of the curvature of the tube 1 on the production line, breaking through the limitations of traditional offline detection. The curved tube 1 passes through the tube passage hole of the motion platform 5 and the continuum mechanism 2, contacting the inner cavity of the continuum mechanism 2, causing the continuum mechanism 2 to deform. This in turn causes the telescopic structural bone 2c to deform and slip at its end. The displacement measurement mechanism 4 detects the displacement of the sliding end of the telescopic structural bone 2c to calculate the bending angle and bending direction angle. After the tube 1 leaves, the continuum mechanism 2 can restore its shape to test the next tube, greatly improving detection efficiency and ensuring production continuity.

[0057] In one possible approach, a pipe with qualified curvature is directly fed into the continuum mechanism 2 to obtain the displacement of the active end of each telescopic structural bone 2c when the curvature is qualified, and then compared with the displacement data of the active end of each telescopic structural bone 2c when the tested pipe enters the continuum mechanism 2 to evaluate whether the curvature is qualified.

[0058] Based on the description of the above-mentioned measuring device and measuring process, the following briefly describes the process of using another method to determine whether the bending angle and bending direction angle are qualified. It should be noted that the following calculation process is not the only method, nor is it a limitation on the calculation method. Based on conditions such as spatial geometric relationships, different calculation methods can be selected as needed during implementation.

[0059] When the non-bent pipe is passed through the terminal disk of the measuring device, the multiple telescopic structural bones are coplanar with the rotating pair connection points of the reversing mechanism, and the plane is perpendicular to the axis of the pipe. At this time, the position of the slider of the linear displacement measuring device in the guide rail is the measurement zero position.

[0060] See Figure 9 When the curved pipe passes through the end plate of the measuring device, the curvature radius R of the pipe enclosed by the continuum is T The length of the fixed structural bone remains constant because its ends are fixed. The three dashed arcs represent the telescopic structural bone. From bottom to top, the base plate, two spacer plates, and the terminal plate are denoted by plate i, where i = 0, 1, 2, and 3, respectively.

[0061] See Figure 10 , which is a top view of the i-th disk. The holes where the three telescopic structural bones are located are numbered 1, 2 and 3 in counterclockwise order. The hole where the fixed structural bone is located is numbered 4. The hole where the pipe passes through the center of the hole is numbered 5. Establish the coordinate system {O i}, its origin O i coincides with 4, where The direction of the axis is parallel to the direction of the line connecting the hole numbered 5 and pointing to 1. The axis is perpendicular to each disk and faces upward. The axes are constructed according to the right-hand rule. i}of The direction of the axis is {O i}Coordinate system around The angle is obtained by rotating the shaft by an angle Φ, which can be found in Figure 9 ,Φ∈(0,2π). Φ can also be viewed as two planes X Oi O i Z Oi With X Pi O i Z Pi The angle between The axes are located at X Pi OZ Pi plane, and converge at a point O on the plane r , O r This is the center of curvature. and The angle is θ.

[0062] like Figure 9 As shown, θ and Φ represent the tube's bending angle and bending direction, respectively. Assuming the tube is a constant curvature arc within the measurement device, and given its maximum rigidity, the other structural bones are assumed to also be constant curvature arcs when bent. The bending radii of the telescopic structural bones passing through holes 1, 2, and 3 are denoted by r1, r2, and r3, respectively. The bending radius of the fixed structural bone passing through hole 4 is denoted by r4. The bending radius of the tube passing through hole 5 is r5. By determining θ, Φ, and r5, the real-time shape of the enclosed curved tube segment can be described.

[0063] like Figure 9 、 10 As shown, since the geometric dimensions of each disk are fixed, the numbered holes on each disk are perpendicular to The distance between the axis (perpendicular to the bending plane) and the distance between the numbered holes on each disk and the The distance between the axes is d j (j = 1, 2, 3, 4, 5). The following relationship exists between the curvature radius r4 of the fixed structural bone and the curvature radius of the remaining telescopic structural bones and pipes enclosed in the holes numbered j = 1, 2, 3, 5:

[0064] r4=r j -d j

[0065] like Figure 9 、 11 As shown in the figure, since the telescopic structural bone will produce axial length changes with the deformation of the continuum, the current length of the telescopic structural bone between the termination plate and the base plate through the 1st, 2nd, and 3rd holes is defined as L k (k = 1, 2, 3). Define the length of the fixed structural bone as L4, and this length is a fixed value. The length of the pipe between the end plate and the base plate is L5. The displacement and expansion of each telescopic structural bone is:

[0066] ΔL k =L k -L4,k=1,2,3

[0067] When the measuring device is in the initial straight state, the length of the kth telescopic structure bone is recorded as the reference length L 0k The angle between the reversing link connected to the kth telescopic structure bone and the telescopic structure bone is recorded as the reference angle β k , β k ∈(0,π). The position of the kth slider on the guide rail at this time is recorded as the reference position H 0k , the displacement and expansion of the slider on the guide rail ΔH k The length of the reversing connecting rod is fixed length L B , by the triangular relationship, we have:

[0068]

[0069]

[0070] Thus, the displacement of the slider ΔH is achieved i Displacement and expansion of the telescopic structure bone ΔL k The mapping relationship.

[0071] In determining ΔL k After that, the arc length of each structural bone and the enclosed tube segment can be determined by integrating the arc length differential element ds:

[0072]

[0073] Substitute the ΔL obtained in the above explanation into k , we can get

[0074] Based on the assumptions described above, all arc lengths share a common central angle θ, so using L4 as a fixed length and the relationship in arc geometry, we have:

[0075]

[0076] According to the assumptions in the above description, the center of curvature O r Located in X pi On the axis, we can get O r In X pi O pi Z pi Coordinates on the plane. And the X1, X2, and X3 axes all point to O r . Then use r4=r j -d j , we can find r j . Thus determine the curvature of the pipe

[0077] Since the arc formed by each secondary rod projected onto the bending plane has the same central angle θ, we can establish a mathematical relationship between any two telescopic structural bones, or any telescopic structural bone and the tube. For example, for the arc lengths l1 and l2, we have:

[0078] ΔL1d2=ΔL2d1

[0079] (l1-l0)d2=(l2-l0)d1

[0080] The same applies to other numbers.

[0081] like Figure 9 、 10 As shown, continuing with the example of arc lengths l1 and l2, considering that d1=R1cos(Φ+Φ1)d2=R2cos(Φ-Φ2), d3=R3cos(Φ-Φ3), d4=0, d5=R5cos(Φ-Φ5),

[0082] R3=d3, R5=d5 and the trigonometric function relationship is:

[0083] ΔL1d2=ΔL2d1

[0084] ΔL1R2cos(Φ-Φ2)=ΔL2R1cos(Φ+Φ1)

[0085] ΔL1R2(cosΦcosΦ2+sinΦsinΦ2)=ΔL2R1(cosΦcosΦ1-sinΦsinΦ1)

[0086] Dividing both sides of the equation by cosΦ, we have:

[0087]

[0088] Taking the inverse function on both sides of the equation, we get:

[0089]

[0090] Considering Φ∈(0,2π), we can further have:

[0091] Φ=atan2(ΔL2R1cosΦ1-ΔL1R2cosΦ2,ΔL1R2sinΦ2+ΔL2R1sinΦ1)

[0092] in,

[0093] The same applies to other numbers.

[0094] In summary, the three-dimensional bending state of the pipe is described by determining θ, Φ and k4 of the measured pipe section.

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and description of the present invention.

Claims

1. An online pipe curvature measurement device based on a continuum mechanism, characterized by: It includes a motion platform (5), a continuum mechanism (2) and a displacement measuring mechanism (4); The middle of the motion platform (5) is provided with a pipe passage hole; The continuum structure (2) is also provided with a pipe passing hole and can be bent and deformed according to the shape of the inserted pipe (1). The continuum structure (2) includes a terminating disc (2a), a spacer disc (2b), a base disc (2f), a telescopic structural bone (2c), a fixed structural bone (2d) and a return spring (2e); The base plate (2f) is fixedly mounted on the motion platform (5) and the pipes (1) therebetween are aligned through holes. At least one spacer plate (2b) is arranged between the termination plate (2a) and the base plate (2f). A plurality of reset springs (2e) are respectively arranged between any two adjacent plates. The two ends of the fixed structural bone (2d) are respectively connected to the termination plate (2a) and the base plate (2f), and the middle part passes through the spacer plate (2b). At least three telescopic structural bones (2c) are arranged in an equidistant circular array. After one end of each telescopic structural bone (2c) is connected to the termination plate (2a), it slides through the spacer plate (2b) and the base plate (2f) in sequence and is finally connected to the displacement measuring mechanism (4). The displacement measuring mechanism (4) is capable of detecting the displacement of the telescopic structural bone (2c).

2. The on-line pipe curvature measuring device based on a continuum mechanism according to claim 1, characterized in that: The displacement measuring mechanism (4) and the sliding end of the telescopic structural bone (2c) are connected via a reversing connecting rod (3); one end of the reversing connecting rod (3) is hinged to the sliding end of the telescopic structural bone (2c), and the other end is connected to the displacement measuring mechanism (4); the displacement measuring mechanism (4) is located on the periphery of the motion platform (5).

3. The on-line pipe curvature measuring device based on a continuum mechanism according to claim 2, characterized in that: The displacement measuring mechanism (4) comprises a slider (4b), a linear displacement measuring unit and a guide rail, wherein the guide rail is arranged on the motion platform (5) and faces the center of the motion platform (5), the slider (4b) is slidably arranged in the guide rail and is hinged to the reversing connecting rod (3), and the linear displacement measuring unit is capable of detecting the sliding amount of the slider (4b).

4. The on-line pipe curvature measuring device based on a continuum mechanism according to claim 3, characterized in that: The linear displacement measuring unit is a slider type displacement sensor, or a wire type sensor, or a laser triangulation sensor, or a grating sensor.

5. The on-line pipe curvature measuring device based on a continuum mechanism according to claim 4, characterized in that: When the linear displacement measuring unit uses a grating sensor, it comprises a grating ruler (4a) arranged on the guide rail and a grating detection head fixedly mounted on the slider (4b), the grating detection head facing the grating ruler (4a).

6. The on-line pipe curvature measuring device based on a continuum mechanism according to claim 1, characterized in that: The telescopic structural bone (2c) and / or the fixed structural bone (2d) are rod-shaped and made of an alloy material with superelastic properties.

7. The on-line pipe curvature measuring device based on a continuum mechanism according to claim 1, characterized in that: It also includes a guide flange (2g), which is opposite to the base plate (2f) and is installed at the inlet end of the pipe (1) through the hole.

8. The on-line pipe curvature measuring device based on a continuum mechanism according to claim 1, characterized in that: The opposing surfaces between the adjacent terminating disc (2a) and the spacing disc (2b), the spacing disc (2b) and the spacing disc (2b), and the spacing disc (2b) and the base disc (2f) are respectively provided with bosses (2aa), and the bosses (2aa) are clamped into the inner rings at both ends of the return spring (2e).

9. The on-line pipe curvature measuring device based on a continuum mechanism according to any one of claims 1 to 8, characterized in that: It also includes a motion mechanism, the motion platform (5) is installed at the motion end of the motion mechanism, the inner hole of the base plate (2f) is provided with a bending structure, and when the motion platform (5) moves, the bending structure bends the pipe (1) passed through.

10. A method for online measurement of pipe curvature based on a continuum mechanism, characterized in that: The on-line pipe curvature measuring device based on a continuum mechanism according to any one of claims 1 to 9 is characterized in that it comprises the following steps: The pipe (1) passes through the pipe (1) through-hole at the center of the motion platform (5) and passes through the pipe through-hole of the continuum mechanism (2); The outer periphery of the tube (1) contacts the inner cavity of the continuum structure (2) and causes the continuum structure (2) to deform, and each of the telescopic structural bones (2c) deforms accordingly, and the sliding end undergoes sliding displacement, the displacement amount being detected by the displacement measuring mechanism (4), and the displacement amount being used to calculate the bending angle and bending direction angle of the tube (1); After the tube (1) leaves the continuum structure (2), the continuum structure (2) recovers its shape.

Images