A digital assembly positioning measurement feedback method and device for a solid engine nozzle

Abstract

The application relates to the technical field of solid engine digital assembly, in particular to a solid engine nozzle digital assembly positioning measurement feedback method and device. The device comprises a measurement positioning plate, a support rod and two flexible self-adapting adjusting mechanisms, the support rod and the two flexible self-adapting adjusting mechanisms are in a triangular distribution through three thrust fastening joints to form a triangular stable support structure, the flexible self-adapting adjusting mechanism provides self-adapting fastening and pre-tightening adjustment through ball hinge cooperation of a ball hinge base and a ball head and a double-end threaded adjusting rod; the method adopts a laser tracker to measure four target ball coordinates and assembly surface feature points, constructs a nozzle local coordinate system and binds the four target ball coordinates as calibration constants, and simultaneously constructs a combustion chamber fixed reference coordinate system; in the assembly process, the target ball coordinates are measured in real time, the real-time six-dimensional position and posture of the nozzle in the reference coordinate system are inversely calculated according to the calibration mapping, position and posture deviation guide data are output, and closed-loop digital assembly control is formed.

Description

Technical Field

[0001] This application relates to the field of digital assembly technology for solid rocket motors, and more specifically, to a method and device for digital assembly positioning measurement feedback of solid rocket motor nozzles. Background Technology

[0002] As the core power plant for aerospace and defense equipment, the quality of the docking and assembly of the nozzle (PG) and combustion chamber (RSS) of a solid rocket motor directly affects the thrust vector accuracy, operational safety, and service reliability of the engine.

[0003] my country's annual output of solid rocket motors has continued to grow, but the assembly process has long suffered from prominent problems such as reliance on manual labor, poor precision consistency, and low efficiency. Traditional solid rocket motor assembly mainly adopts a process of coarse positioning with mechanical guide pins, support with mechanical assembly tables, and manual visual judgment and fine adjustment. Essentially, this is a labor-intensive manual operation mode of "manual + mechanical". This mode requires at least 5 operators to work together, and the total assembly time for a single motor can be as long as 1 to 2 days. Moreover, the assembly accuracy is significantly affected by human factors such as operator experience, visual errors, and physical condition, which makes it difficult to meet the needs of solid rocket motors to develop towards higher precision and higher reliability. With the advancement of digital manufacturing technology, solid rocket motor assembly has put forward higher requirements in terms of capacity improvement and quality consistency, and there is an urgent need to establish a digital assembly positioning feedback process based on high-precision measurement.

[0004] Solid rocket motor nozzles have a conical rotating structure, with their mating surface located inside the large end face of the nozzle. The outer skirt naturally obstructs the assembly interface in the measurement line of sight, making it impossible for non-contact measuring devices such as laser trackers to directly aim at the nozzle assembly reference surface. This makes it difficult to obtain the spatial orientation data of the nozzle relative to the combustion chamber. Furthermore, the nozzle assembly is a horizontal docking, and the nozzle assembly slowly translates along the guide rail during the assembly process. Its spatial orientation changes dynamically with the movement. The traditional "one-time alignment, fixed assembly" method cannot track the orientation changes in real time, nor can it feed back the real-time orientation parameters during the physical assembly process to the digital control system. This contradiction between physical obstruction and dynamic measurement makes it difficult to directly apply existing digital measurement methods to the nozzle assembly process.

[0005] Therefore, there is an urgent need for a method that can effectively externalize the nozzle coordinate system, establish a stable measurement benchmark, and achieve real-time feedback during the assembly process, so as to make full use of the high-precision measurement capabilities of the laser tracker and open up the data channel between the physical assembly space and the digital control space. Summary of the Invention

[0006] In view of this, in order to solve the above-mentioned problems in the prior art, this application provides a digital assembly positioning measurement feedback method and device for solid rocket motor nozzles.

[0007] The embodiments of this application are implemented as follows: In a first aspect, this application provides a digital assembly positioning measurement feedback method for a solid rocket motor nozzle, comprising: Step 100: Install the positioning measurement feedback device on the external structure of the solid rocket motor metal fixture, and fasten it to the exposed circumferential metal end of the solid rocket motor metal fixture through three thrust fastening joints. Adjust the double-threaded adjusting rod to provide preload force for the two flexible adaptive adjustment mechanisms to form a triangular stable support structure. Step 200: Use a laser tracker to measure the first spatial coordinate set of the four target balls on the positioning plate in the measurement coordinate system, and the coordinates of the feature points of the assembly surface on the solid rocket motor metal fixed body in the measurement coordinate system. Based on the feature points of the assembly surface, construct the original local coordinate system of the nozzle, and transform the first spatial coordinate set of the four target balls to the original local coordinate system of the nozzle to obtain the calibration constants and store them in the database. Step 300: Construct the combustion chamber reference coordinate system as a fixed world reference, define the nozzle follower coordinate system as a rigid body fixed coordinate system, establish the coordinate transformation relationship between the first spatial coordinate set and the original local coordinate system of the nozzle, determine the rotation matrix R and translation matrix T for the transformation from the measurement coordinate system to the nozzle follower coordinate system, and describe the six-dimensional pose of the nozzle follower coordinate system relative to the combustion chamber reference coordinate system through the homogeneous transformation matrix. Step 400: During the solid rocket motor docking and assembly process, a laser tracker is used to measure the second spatial coordinate set of the four target spheres in the measurement coordinate system in real time; Step 500: Based on the second spatial coordinate set, the rotation matrix R, and the translation matrix T, calculate the real-time six-dimensional pose of the nozzle in the combustion chamber reference coordinate system by combining the calibration constant. Step 600: Based on the deviation between the real-time six-dimensional pose and the target assembly pose parameters, output assembly guidance data, adjust the pose of the solid rocket motor, and complete the digital assembly control.

[0008] In one possible implementation, constructing the nozzle's original local coordinate system based on the assembly surface feature points specifically includes: The least squares fit is performed on the planar features in the feature points of the assembly surface to obtain the assembly reference plane. The normal vector of the assembly reference plane is defined as the local X-axis, with the direction pointing to the surface to be assembled being the positive direction. The quadrant points among the feature points of the assembly surface are taken as local features, and the local Y-axis is defined by the vector direction from the outer circle center of the assembly reference plane to the quadrant point. The local Z-axis is calculated using the cross product of the right-hand coordinate system. The origin of the coordinate system is then used as the center of the hole axis theory to complete the construction of the original local coordinate system of the nozzle.

[0009] In one possible implementation, the formula for the inversion calculation in step 500 is expressed as: ; in, The matrix formed by the second spatial coordinate set. Rotation matrix The inverse matrix, It is a translation matrix. The real-time coordinate set in the original local coordinate system of the nozzle obtained by inversion calculation, combined with the calibration constant, will The position of the nozzle follower coordinate system is mapped to the real-time six-dimensional pose of the combustion chamber reference coordinate system.

[0010] In one possible implementation, the target assembly pose parameters include the nozzle axis direction vector, the position of the nozzle end face center point, and the rotation angle of the nozzle around the axis, and the assembly guidance data includes the deviation values ​​of each parameter direction and the adjustment direction indication.

[0011] Secondly, this application provides a digital assembly positioning measurement feedback device for a solid rocket motor nozzle, used to implement any of the aforementioned digital assembly positioning measurement feedback methods for solid rocket motor nozzles, comprising a measurement positioning plate, a support rod, and two flexible adaptive adjustment mechanisms: The measuring positioning plate has a through hole in the middle and four measuring target seats on the front. Target balls are installed on the measuring target seats. The measuring positioning plate is used to cooperate with the laser tracker through the target balls to establish a measurable spatial positioning reference outside the nozzle. One end of the support rod is fixedly connected to the through hole, and the other end of the support rod is fastened to the exposed circumferential metal end of the solid rocket motor metal fixture. The support rod is used to fix and support the measuring positioning plate on the solid rocket motor metal fixture and to transmit the load and torque during the measurement process. Two flexible adaptive adjustment mechanisms are symmetrically arranged on both sides of the support rod. One end of the flexible adaptive adjustment mechanism is fixedly connected to the measuring positioning plate, and the other end of the flexible adaptive adjustment mechanism is fastened to the exposed circumferential metal end of the solid rocket motor metal fixture. The flexible adaptive adjustment mechanism is used to adaptively adjust the angle and apply preload, so that the support rod and the two flexible adaptive adjustment mechanisms together form a triangular stable support structure to ensure the spatial position stability of the target ball during assembly.

[0012] In one possible implementation, the support rod includes a fixed joint, an adapter, a threaded connecting rod, a double-ended threaded adjusting rod, a thrust fastening joint, and a threaded stud. The first end of the fixed joint is disposed at the through hole of the measuring positioning plate, and is used to initially position and connect the support rod to the measuring positioning plate; The first end of the adapter is fixedly connected to the second end of the fixed connector, and the second end of the adapter is fixedly connected to the first end of the threaded connecting rod. The second end of the threaded connecting rod is provided with an internal thread, and the first end of the double-ended threaded adjusting rod is provided with an external thread. The second end of the threaded connecting rod is threadedly connected to the first end of the double-ended threaded adjusting rod. The second end of the double-ended threaded adjusting rod is provided with an external thread and is connected to the internal thread of the second end of another threaded connecting rod. The first end of the other threaded connecting rod is connected to the second end of another adapter. The double-ended threaded adjusting rod is used to adjust the engagement depth of the two threaded connecting rods at both ends by rotation, so as to realize the overall length adjustment of the support rod and the application of preload. The first end of the other adapter is fixedly connected to the first end of the thrust fastening joint, and the second end of the thrust fastening joint is located at the exposed circumferential metal end of the solid rocket motor metal fixture. Both the first end of the fixed joint and the second end of the thrust fastening joint are provided with U-shaped clamping heads, and a fastening hole is provided on one side of the U-shaped clamping head. The U-shaped clamping head is used to clamp and fix the exposed circumferential metal end of the measuring positioning plate and the solid rocket motor metal fixing body. The threaded head passes through the fastening hole, fastening the fixing joint to the measuring positioning plate, and simultaneously fastening the thrust fastening joint to the exposed circumferential metal end of the solid rocket motor metal fixing body. The threaded head is used to achieve quick assembly and disassembly and reliable locking.

[0013] In one possible implementation, the first end of the adapter is provided with an external thread, and the second end of the fixed connector and the first end of the thrust fastening connector are both provided with internal threaded holes. The first end of the adapter is threadedly connected to the second end of the fixed connector and the first end of the thrust fastening connector, and is locked and fixed by a hexagonal nut. The second end of the converter head is provided with four circumferentially distributed connecting holes, and the first end of the threaded connecting rod is fixedly connected to the second end of the converter head by passing through the connecting holes with screws.

[0014] In one possible implementation, the flexible adaptive adjustment mechanism includes a threaded connecting rod, a double-ended threaded adjusting rod, a ball joint seat, a ball head, a thrust fastening joint, and a threaded column head. The first end of the ball head is fixedly connected to the side of the measuring positioning plate, and the second end of the ball head is engaged with the first end of the ball joint seat. The ball head is used to transmit the constraint force of the measuring positioning plate to the ball joint seat and achieve adaptive adjustment of the angle through spherical engagement. The second end of the ball joint seat is fixedly connected to the first end of the threaded connecting rod, the second end of the threaded connecting rod is threadedly connected to the first end of the double-ended threaded adjusting rod, the second end of the double-ended threaded adjusting rod is connected to the second end of another threaded connecting rod, and the first end of another threaded connecting rod is fixedly connected to the second end of another ball joint seat. The first end of another ball joint seat is connected to the second end of another ball head, and the first end of another ball head is fixedly connected to the first end of the thrust fastening joint. The ball joint seat and the ball head are used to adaptively adjust the angle when the solid rocket motor metal fixed body is displaced or deflected, so as to avoid stress concentration caused by rigid connection. The second end of the thrust fastening joint is fastened to the exposed circumferential metal end of the solid rocket motor metal fixture via the threaded post, for detachably fixing the flexible adaptive adjustment mechanism to the solid rocket motor metal fixture.

[0015] In one possible implementation, the second end of the ball joint seat is provided with four circumferentially distributed through holes, and the first end of the threaded connecting rod is provided with four circumferentially distributed threaded holes. Four screws pass through the four through holes of the ball joint seat and are threadedly engaged with the four threaded holes of the threaded connecting rod to fix the ball joint seat to the first end of the threaded connecting rod.

[0016] In one possible implementation, the first end of the ball head is provided with an external thread, and the first end of the ball head is threadedly connected to the side of the measuring positioning plate and the first end of the thrust fastening joint, and is locked by a nut; The first end of the ball joint seat is provided with an inner spherical structure, and the second end of the ball head is provided with an outer spherical structure. The second end of the ball head is rotatably fitted into the first end of the ball joint seat to form a ball joint engagement. The ball joint engagement is used to realize adaptive adjustment of angular displacement in at least two degrees of freedom, so that the flexible adaptive adjustment mechanism can adapt to the positional changes of the solid rocket motor metal fixture during assembly, while maintaining the stability of the triangular stable support structure.

[0017] The technical solution provided in this application can achieve at least the following beneficial effects: This application provides a digital assembly positioning measurement feedback method and device for solid rocket motor nozzles. By using an adjustable triangular stable support structure consisting of four target balls on the measurement positioning plate, a support rod, and flexible adaptive adjustment mechanisms on both sides, the measurement reference is placed outside the nozzle. The ball joint between the ball joint seat and the ball head, along with the pre-tightening adjustment of the double-ended threaded adjustment rod, achieves adaptive fastening and multi-model compatibility, overcoming the physical limitation that the assembly interface cannot be directly measured due to the obstruction of the nozzle's conical skirt.

[0018] Simultaneously, the coordinates of four target spheres and feature points of the assembly surface were acquired by a laser tracker. Based on least squares fitting, the original local coordinate system of the nozzle was constructed, and the coordinates of the four target spheres were bound to the nozzle coordinate system as calibration constants and stored in the database. This realized an engineering mode of one-time calibration and multiple uses. Furthermore, a fixed reference coordinate system of the combustion chamber was constructed. Using four-point least squares estimation and homogeneous transformation matrix, the coordinates of the target spheres in the measurement coordinate system were converted into a six-dimensional pose of the nozzle follower coordinate system relative to the reference coordinate system. Linear least squares replaced the nonlinear multivariate function optimization relied upon by the traditional three-point method, achieving high-precision and stable coordinate transformation.

[0019] During assembly, the coordinates of the four target balls are measured in real time and the real-time six-dimensional pose of the nozzle is inverted, forming a closed-loop digital assembly control of measurement, calculation and feedback. The assembly guidance data, including position deviation, axial direction deviation and rotation angle deviation, is output in real time. The operator adjusts the nozzle pose according to the guidance data until each deviation is less than the preset threshold. This effectively replaces the traditional mechanical guide pin plus manual visual assembly method, and significantly improves the accuracy, consistency, efficiency and digitalization level of solid rocket motor nozzle assembly. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a flowchart illustrating an exemplary embodiment of a solid rocket motor nozzle digital assembly positioning measurement feedback method. Figure 2 This is a schematic diagram of the overall structure of a digital assembly positioning measurement feedback device for a solid rocket motor nozzle, as shown in an exemplary embodiment of this application. Figure 3 This is a schematic diagram of the front view structure of the measuring positioning plate shown in an exemplary embodiment of this application; Figure 4This is a side view of the measurement positioning plate shown in an exemplary embodiment of this application; Figure 5 This is a schematic front view of the fixed connector shown in an exemplary embodiment of this application; Figure 6 This is a side view of the fixed joint structure shown in an exemplary embodiment of this application; Figure 7 This is a side view of a threaded connecting rod shown in an exemplary embodiment of this application; Figure 8 This is a schematic front view of a threaded connecting rod shown in an exemplary embodiment of this application; Figure 9 This is a schematic front view of a double-threaded adjusting rod shown in an exemplary embodiment of this application; Figure 10 This is a side view of a double-ended threaded adjusting rod as illustrated in an exemplary embodiment of this application; Figure 11 This is a schematic diagram of the main structure of the converter head shown in an exemplary embodiment of this application; Figure 12 This is a top view of the converter head shown in an exemplary embodiment of this application; Figure 13 This is a schematic front view of the ball joint seat shown in an exemplary embodiment of this application; Figure 14 This is a top view of the ball joint seat shown in an exemplary embodiment of this application; Figure 15 This is a schematic diagram of the front view structure of the ball head shown in an exemplary embodiment of this application; Figure 16 This is a schematic side view of the ball head structure shown in an exemplary embodiment of this application; Figure 17 This is a schematic front view of the thrust fastening joint shown in an exemplary embodiment of this application; Figure 18 This is a side view of the thrust fastening joint shown in an exemplary embodiment of this application; Figure 19 This is a schematic front view of the measurement target structure shown in an exemplary embodiment of this application; Figure 20 This is a side view of the measurement target structure shown in an exemplary embodiment of this application; Figure 21 This is a schematic front view of the threaded cylinder head shown in an exemplary embodiment of this application; Figure 22 This is a side view of the threaded head structure shown in an exemplary embodiment of this application.

[0022] Figure label: 1. Measuring positioning plate; 2. Fixed joint; 3. Threaded connecting rod; 4. Double-ended threaded adjusting rod; 5. Converter head; 6. Ball joint seat; 7. Ball head; 8. Thrust fastening joint; 9. Measuring target seat; 10. Threaded column head. Detailed Implementation

[0023] To make the objectives, implementation methods and advantages of this application clearer, the exemplary implementation methods of this application will be clearly and completely described below with reference to the accompanying drawings of the exemplary embodiments of this application. Obviously, the exemplary embodiments described are only some embodiments of this application, and not all embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0024] It should be noted that the brief descriptions of terms in this application are only for the convenience of understanding the embodiments described below, and are not intended to limit the embodiments of this application. Unless otherwise stated, these terms should be understood in their ordinary and common meaning.

[0025] The terms “first,” “second,” “third,” etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar or related objects or entities, and do not necessarily imply a specific order or sequence. Unless otherwise stated, it should be understood that such terms can be used interchangeably where appropriate.

[0026] The terms “comprising” and “having”, and any variations thereof, are intended to cover but not exclude inclusion, for example, a product or device that includes a range of components is not necessarily limited to all of the components that are clearly listed, but may include other components that are not clearly listed or that are inherent to such product or device.

[0027] Next, the technical solutions of this application and how they solve the aforementioned technical problems will be described in detail through embodiments and in conjunction with the accompanying drawings. The embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of this application.

[0028] In one exemplary embodiment, such as Figure 1 As shown, the digital assembly positioning measurement feedback method for solid rocket motor nozzles may include the following steps: Step 100: Install the positioning measurement feedback device on the external structure of the solid rocket motor metal fixture, and fasten it to the exposed circumferential metal end of the solid rocket motor metal fixture through three thrust fastening joints. Adjust the double-threaded adjusting rod to provide preload force for the two flexible adaptive adjustment mechanisms to form a triangular stable support structure.

[0029] In some embodiments, the specific implementation process of this step is as follows: First, select a suitable installation location based on the model and specifications of the solid rocket motor to be assembled. The device is typically installed on the mounting ring of the lower lug of the solid rocket motor nozzle. This mounting ring is a pre-installed metal annular structure on the nozzle housing, possessing sufficient structural strength to support the device.

[0030] During installation, align the U-shaped clamping head of the thrust fastening connector 8 of the support rod with the exposed circumferential metal end of the nozzle lower support lug mounting ring, so that the exposed circumferential metal end is embedded in the U-shaped clamping space. Then, pass the threaded stud 10 through the fastening holes on the U-shaped clamping head in sequence. The threaded stud 10 directly penetrates the fastening hole and clamps the surface of the exposed circumferential metal end. Tighten the nut to fasten the thrust fastening connector 8 to the exposed circumferential metal end.

[0031] The same operation is performed to fasten the thrust fastening joints 8 of the flexible adaptive adjustment mechanism on both sides to the exposed circumferential metal end of the nozzle lower support lug mounting ring. The three thrust fastening joints 8 are evenly distributed on the mounting ring, forming a triangular layout. The three connection points are at 120° angles to each other to ensure uniform force distribution.

[0032] After the initial tightening of the three thrust fastening joints 8 is completed, the operator adjusts the support rod and the double-threaded adjusting rod 4 in the two flexible adaptive adjustment mechanisms respectively. Specifically, the operator uses a wrench to hold the adjusting part in the middle of the double-threaded adjusting rod 4 and rotates the double-threaded adjusting rod 4 in the forward or reverse direction so that the threaded connecting rods 3 at both ends of the double-threaded adjusting rod 4 move closer or further away at the same time, thereby generating a pre-tightening force on the support rod or the flexible adaptive adjustment mechanism. The magnitude of the pre-tightening force is determined according to the actual installation needs. Generally, it is advisable to visually ensure that the support rod and the flexible adaptive adjustment mechanism are in a taut state and that there are no obvious gaps between the components.

[0033] After adjustment, check again whether the connecting screws and nuts of the three thrust fastening joints 8 are fully tightened to ensure that there is no looseness in each connection part. At this time, the support rod and the two flexible adaptive adjustment mechanisms together form a triangular stable support structure, and the measurement positioning plate 1 is in a stable state relative to the solid engine metal fixed body.

[0034] Step 200: Use a laser tracker to measure the first spatial coordinate set of the four target balls on the positioning plate in the measurement coordinate system, and the coordinates of the feature points of the assembly surface on the solid rocket motor metal fixture in the measurement coordinate system. Based on the feature points of the assembly surface, construct the original local coordinate system of the nozzle, and transform the first spatial coordinate set of the four target balls to the original local coordinate system of the nozzle to obtain the calibration constants and store them in the database.

[0035] In some embodiments, the specific implementation process of this step is as follows: After the device is installed, the operator will place the laser tracker at an appropriate location on the solid rocket motor assembly site to ensure that the laser tracker's measurement field of view can cover the four target balls on the measurement positioning plate 1 and the feature points on the solid rocket motor metal fixture.

[0036] Measure the first spatial coordinate set of the four target spheres: The operator starts the laser tracker and its matching measurement software, aligns the laser beam of the laser tracker with the first target ball on the measurement positioning plate 1, and records the spatial coordinates (Q1x, Q1y, Q1z) of the target ball in the measurement coordinate system using the measurement software. Then, the second, third, and fourth target balls are measured in sequence, and their coordinates (Q2x, Q2y, Q2z), (Q3x, Q3y, Q3z), and (Q4x, Q4y, Q4z) in the measurement coordinate system are recorded respectively. The measured coordinates of the four target balls together constitute the first spatial coordinate set. The measurement coordinate system is the coordinate system defined by the laser tracker itself, usually with the center of the laser tracker's position as the origin.

[0037] Measure the feature points of the assembly surface and construct the original local coordinate system of the nozzle: The feature points are the mounting surface features on the metal fixture of the solid rocket motor nozzle, including planar features, circular features (cylindrical surfaces) and quadrant point positioning features. In the preferred embodiment, the mounting reference plane, outer cylindrical surface and quadrant point on the nozzle lower support lug mounting ring are selected as features.

[0038] The operator used a laser tracker to collect the spatial coordinate data of the above feature points. Based on the collected feature point data, the following coordinate system construction algorithm was executed: 1. Perform least-squares fitting on the planar feature point cloud to obtain the assembly reference plane, and define the normal vector of this plane as the local X-axis. ; 2. Perform least-squares fitting on the feature point cloud of the cylindrical surface to obtain the axis of the outer cylinder of the nozzle. Project this axis onto the assembly reference plane, and define the projection direction as the local Y-axis. ; 3. Calculate the local Z-axis using the cross product in a right-handed coordinate system. ; 4. The origin of the coordinate system is the theoretical mating center of the hole and shaft. Complete the original local coordinate system of the nozzle. The construction.

[0039] Measure and calibrate the binding (binding) of the coordinates of the four target spheres to the original local coordinate system of the nozzle: The laser tracker sequentially measures the centers of four target spheres to obtain their coordinates in a global temporary measurement coordinate system. By using the coordinate system transformation matrix, All converted to the original local coordinate system of the nozzle The calibration constant is obtained. .

[0040] The calibration constant is stored in the industrial control database and cannot be modified during on-site online measurement. This realizes an engineering mode of one-time calibration and multiple uses. The determinant of the four-point covariance matrix is ​​satisfied, and the single-point repeatability of the laser tracker measurement is ≤0.02mm, ensuring calibration accuracy.

[0041] Step 300: Construct the combustion chamber reference coordinate system as a fixed world reference, define the nozzle follower coordinate system as a rigid body fixed coordinate system, establish the coordinate transformation relationship between the first spatial coordinate set and the original local coordinate system of the nozzle, determine the rotation matrix R and translation matrix T for the transformation from the measurement coordinate system to the nozzle follower coordinate system, and describe the six-dimensional pose of the nozzle follower coordinate system relative to the combustion chamber reference coordinate system through the homogeneous transformation matrix.

[0042] In some embodiments, the core of this step is to establish the transformation relationship between the measurement coordinate system and the nozzle coordinate system, and to incorporate it into a unified rigid body pose description framework.

[0043] Given the coordinates of the four target spheres in the measurement coordinate system (first spatial coordinate set) and the calibration constants in the original local coordinate system of the nozzle. Since the measuring target ball is fixedly connected to the measuring positioning plate 1, and the measuring positioning plate 1 is rigidly connected to the solid rocket motor metal fixed body through the support rod, the four target balls and the nozzle features have a fixed spatial positional relationship. Through this fixed relationship, a transformation matrix between the two coordinate systems can be established.

[0044] Combustion chamber reference coordinate system In the assembly scenario, the combustion chamber is a fixed component, and its coordinate system is the reference coordinate system. The origin is usually the center of the combustion chamber docking end face, the quadrant feature direction is the Y-axis vector, and the nozzle assembly feed direction is the Z-axis.

[0045] Nozzle follower coordinate system It is rigidly connected to the nozzle body and moves with the translation and rotation of the nozzle, with a six-dimensional pose output. .

[0046] Some embodiments of this application employ four-point least squares estimation to rewrite the coordinate transformation relationship into the standard form of multiple regression analysis and solve it, specifically including: The coordinate transformation relationship can be rewritten in the standard form of multiple regression analysis, expressed by the formula: ; in,( , , ) is the first The coordinates of a feature point in the solid rocket motor docking coordinate system, ( , , ) is the first The coordinates of the target spheres in the measurement coordinate system, i=1,2,3,4 The matrix formed by the second spatial coordinate set. The matrix formed by the first spatial coordinate set. Let be the transformation parameter matrix to be estimated, the transformation parameter matrix It contains elements of the rotation matrix R and the translation matrix T; The transformation parameter matrix is ​​solved using the least squares method. The transformation parameter matrix The estimated value Determine the rotation matrix R and the translation matrix T, and the transformation parameter matrix. The estimated value This can be expressed by the formula: ; The rotation matrix R and the translation matrix T are expressed by the following formulas: ; The rotation matrix R satisfies orthogonality and unity.

[0047] This application employs a least squares estimation method based on matrix multiplication using four feature points, which has significant advantages over the traditional three-point method. Although the traditional three-point method can theoretically determine the transformation matrix using only three points, the actual solution process requires solving a complex multivariate function optimization problem. The solution depends on the given initial parameters and the setting of algorithm control parameters, resulting in poor stability. In contrast, this method transforms the nonlinear optimization problem into a linear least squares problem, requiring no initial parameter setting, and is computationally stable and reliable with a unique solution.

[0048] Furthermore, this application utilizes a homogeneous transformation matrix. The pose mapping of the nozzle follower coordinate system relative to the combustion chamber reference coordinate system is described by a matrix carrier of six-dimensional data: ; Among them, the translation vector .

[0049] The overall rotation matrix R is constructed by first rotating γ around the Z-axis, then β around the Y-axis, and finally α around the X-axis. The single-axis rotation matrices are as follows: ; ; ; in, .

[0050] Total rotation matrix Expanded as: ; in, for , for , for , for , for , for .

[0051] Step 400: During the solid rocket motor docking and assembly process, a laser tracker is used to measure the second spatial coordinate set of the four target spheres in the measurement coordinate system in real time.

[0052] In some embodiments, the specific implementation process of this step is as follows: After establishing the coordinate transformation relationship, the actual docking and assembly stage can begin. The docking and assembly of the solid rocket motor nozzle and the combustion chamber is usually carried out on a horizontal assembly line. The nozzle is supported by a support trolley and slowly moves towards the combustion chamber along the guide rail.

[0053] During the translation of the nozzle, the spatial pose of the nozzle will change slightly relative to the initial calibration state due to factors such as the straightness error of the guide rail, the travel error of the trolley, and the deformation of the nozzle itself under gravity. In order to track the change of the nozzle's pose in real time, it is necessary to continuously measure the spatial coordinates of the four target balls on the positioning plate 1.

[0054] The operator starts the continuous measurement mode of the laser tracker. The laser tracker automatically tracks the position of the four target balls and sequentially collects the real-time spatial coordinates of the four target balls in the measurement coordinate system at a preset sampling frequency. Each sampling obtains the measurement coordinates (P1x,P1y,P1z), (P2x,P2y,P2z), (P3x,P3y,P3z), and (P4x,P4y,P4z) of the four target balls, which together constitute the second spatial coordinate set.

[0055] To ensure the continuity of real-time measurements, the laser tracker and the measurement software transmit measurement data in real time via a data cable or wireless network. The measurement software receives and stores the second spatial coordinate set in real time for use in subsequent steps.

[0056] Step 500: Based on the second spatial coordinate set, the rotation matrix R, and the translation matrix T, calculate the real-time six-dimensional pose of the nozzle in the combustion chamber reference coordinate system by combining the calibration constant.

[0057] In some embodiments, the specific implementation process of this step is as follows: Based on the rotation matrix R and translation matrix T determined in step 300, the second spatial coordinate set measured in real time in step 400 is converted into real-time spatial coordinates in the solid rocket motor docking coordinate system.

[0058] The inversion calculation formula is:

[0059] in, The matrix formed by the second spatial coordinate set. Let R be the inverse of the rotation matrix R, and T be the translation matrix. This is the real-time spatial coordinate set in the solid rocket motor docking coordinate system obtained from the inversion calculation.

[0060] Since the measuring positioning plate 1 is rigidly connected to the nozzle via a support rod, the calibration constants of the four target balls in the original local coordinate system of the nozzle are... Since the four target balls remain unchanged during assembly, once the real-time coordinates of the four target balls in the original local coordinate system of the nozzle are determined, the complete six-dimensional pose parameters of the nozzle in the reference coordinate system of the combustion chamber can be further calculated by using the principle of rigid body kinematics and combining the geometric relationship between the calibration constant and the nozzle design axis.

[0061] Specifically, the real-time coordinate set of the four target spheres obtained by inversion is compared with the calibration constants stored in the database. Matching is performed, and the rotation matrix R and translation vector t of the nozzle follower coordinate system relative to the combustion chamber reference coordinate system are solved through singular value decomposition (SVD) or orthogonal Procrustes analysis, thereby extracting the six-dimensional pose. The six-dimensional pose includes the real-time coordinates and attitude angles of multiple points on the nozzle axis.

[0062] Step 600: Based on the deviation between the real-time six-dimensional pose and the target assembly pose parameters, output assembly guidance data, adjust the pose of the solid rocket motor, and complete the digital assembly control.

[0063] In some embodiments, the specific implementation process of this step is as follows: The real-time six-dimensional pose calculated in step 500 is compared with the target assembly pose parameters to calculate the deviation. The target assembly pose parameters are the theoretical assembly position and attitude of the nozzle obtained from solid rocket motor design drawings or process documents, including the nozzle axis direction vector, the position of the nozzle end face center point, and the rotation angle of the nozzle around the axis.

[0064] Deviation calculation: Positional deviation of the center point of the nozzle docking end face: The components (ΔX, ΔY, ΔZ) of the difference between the real-time coordinates and the target coordinates in the three directions of X, Y, and Z; Nozzle axis direction vector deviation: The angular deviation (Δα, Δβ) between the real-time axis direction vector and the target axis direction vector, corresponding to the pitch angle and yaw angle, respectively; Nozzle rotation angle deviation around the axis: the difference (Δγ) between the real-time rotation angle and the target rotation angle.

[0065] Based on the calculated deviation values, assembly guidance data is generated. The assembly guidance data includes the deviation values ​​of each parameter direction and the adjustment direction indication. For example, the software interface can display guidance information such as "X direction deviation +0.02mm, need to adjust 0.02mm in the negative X direction" and "Pitch angle deviation -0.01°, need to adjust upward 0.01°".

[0066] Operators operate the adjustment mechanism of the nozzle support trolley according to the assembly guidance data to precisely adjust the position and posture of the nozzle.

[0067] The specific adjustment process is as follows: According to the position deviation indication, adjust the translation position of the nozzle in the X, Y, and Z directions so that the center point of the nozzle docking end face gradually approaches the target position. Based on the attitude deviation indication, adjust the rotation angle of the nozzle around the X and Y axes to gradually align the nozzle axis with the target direction; Adjust the nozzle's rotation angle around the Z-axis according to the rotation angle deviation indication to align the nozzle's circumferential positioning mark with the target.

[0068] In some embodiments, steps 400 to 600 are continuously cyclically executed during the adjustment of the solid rocket motor's pose. Specifically, after each fine-tuning operation, the laser tracker immediately remeasures the real-time coordinates of the four target spheres, the measurement software recalculates the real-time spatial coordinate set and deviation value, and outputs updated assembly guidance data. This high-frequency measurement, calculation, and feedback loop forms a closed-loop digital assembly control, ensuring that the nozzle's pose is always under control.

[0069] When all deviation values ​​are less than the preset threshold, the measurement software outputs an "assembly in place" instruction, the operator stops adjusting, and the digital assembly control is completed. Finally, the nozzle and combustion chamber are docked within the preset accuracy range, and subsequent fastening connection operations can be carried out.

[0070] It should be understood that although the steps in the flowcharts of the above embodiments are shown sequentially as indicated, these steps are not necessarily executed in the indicated order. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the above embodiments may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages in other steps.

[0071] Corresponding to the aforementioned embodiments of the digital assembly positioning measurement feedback method for solid rocket motor nozzles, and employing the same technical concept, this application also provides embodiments of a digital assembly positioning measurement feedback device for solid rocket motor nozzles.

[0072] In one exemplary embodiment, such as Figure 2 As shown, a digital assembly positioning measurement feedback device for solid rocket motor nozzles is provided. In this embodiment, the device may include a measurement positioning plate 1, a support rod, and two flexible adaptive adjustment mechanisms. The measuring positioning plate 1 has a through hole in the middle and four measuring target seats 9 are provided on the front side of the measuring positioning plate 1. Target balls are installed on the measuring target seats 9. The measuring positioning plate 1 is used to cooperate with the laser tracker through the target balls to establish a measurable spatial positioning reference outside the nozzle. One end of the support rod is fixedly connected to the through hole, and the other end of the support rod is fastened to the exposed circumferential metal end of the solid rocket motor metal fixture. The support rod is used to fix and support the measuring positioning plate on the solid rocket motor metal fixture and to transmit the load and torque during the measurement process. Two flexible adaptive adjustment mechanisms are symmetrically arranged on both sides of the support rod. One end of the flexible adaptive adjustment mechanism is fixedly connected to the measuring positioning plate 1, and the other end of the flexible adaptive adjustment mechanism is fastened to the exposed circumferential metal end of the solid rocket motor metal fixture. The flexible adaptive adjustment mechanism is used to adaptively adjust the angle and apply preload, so that the support rod and the two flexible adaptive adjustment mechanisms together form a triangular stable support structure to ensure the spatial position stability of the target ball during assembly.

[0073] In some embodiments, the digital assembly positioning measurement feedback device for solid rocket motor nozzles is specifically implemented by including a measurement positioning plate 1, a support rod, and two flexible adaptive adjustment mechanisms.

[0074] like Figure 3 and Figure 4 As shown, the measuring positioning plate 1 has a through hole in the middle. The through hole is a circular through hole, and its diameter is adapted to the outer diameter of the fixed joint 2 of the support rod, so as to fix it to the support rod.

[0075] like Figure 19 and Figure 20 As shown, four measuring target seats 9 are set on the front of the measuring positioning plate 1, that is, the side facing the laser tracker during measurement. Each measuring target seat 9 is equipped with a target ball. The target ball is a standard reflective target ball used with the laser tracker to reflect the laser beam emitted by the laser tracker and realize the accurate measurement of spatial coordinates.

[0076] The support rod is a load-bearing component that connects the measuring positioning plate 1 to the solid rocket motor metal fixture. One end of the support rod is fixedly connected to the through hole in the middle of the measuring positioning plate 1, and the other end of the support rod is fastened to the exposed circumferential metal end of the solid rocket motor metal fixture.

[0077] The measuring positioning plate 1 has threaded holes on the side near the solid rocket motor metal fixture for connecting with two flexible adaptive adjustment mechanisms. The two threaded holes are respectively located on the upper and lower sides of the support rod and are used to connect with the ball head 7 of the adaptive adjustment mechanism. Through this symmetrical connection structure, the two flexible adaptive adjustment mechanisms can be symmetrically arranged on both sides of the support rod to form a triangular stable support structure.

[0078] In some embodiments, such as Figure 2 As shown, the support rod includes a fixed joint 2, an adapter 5, a threaded connecting rod 3, a double-ended threaded adjusting rod 4, a thrust fastening joint 8, and a threaded column head 10.

[0079] like Figure 5 and Figure 6As shown, the first end of the fixed connector 2 is located at the through hole of the measuring positioning plate 1. The fixed connector 2 has a cylindrical structure. Its first end, that is, the end closest to the measuring positioning plate 1, is provided with a U-shaped clamping head. The U-shaped clamping head has two opposing clamping arms, and a U-shaped clamping space is formed between the two clamping arms. The edge of the through hole of the measuring positioning plate 1 is embedded in the U-shaped clamping space. The two clamping arms are located on the front and back of the measuring positioning plate 1, respectively. Fastening holes are opened on the two clamping arms. The fastening holes of the two clamping arms are coaxially arranged. The threaded stud 10 passes through the fastening holes of the two clamping arms and the through hole of the measuring positioning plate 1 in sequence to fasten the fixed connector 2 to the measuring positioning plate 1. Preferably, the fastening hole is a through hole, and the threaded stud 10 is a bolt or stud with a hexagonal nut. After passing through the fastening hole, it is locked by a nut to achieve a rigid connection between the fixed connector 2 and the measuring positioning plate 1. The second end of the fixed connector 2, that is, the end away from the measuring positioning plate 1, is provided with an internal threaded hole for connecting with the external thread of the first end of the adapter 5. The outer circumferential surface of the second end of the fixed connector 2 is also provided with an external threaded section for locking the adapter 5 with a hexagonal nut.

[0080] like Figure 11 and Figure 12 As shown, the converter head 5 has a columnar structure. Its first end is provided with an external thread, which is threaded into the internal thread hole of the second end of the fixed connector 2 and locked by a hexagonal nut. The second end of the converter head 5 is provided with four circumferentially distributed connecting holes for fixed connection with the first end of the threaded connecting rod 3.

[0081] like Figure 7 and Figure 8 As shown, the threaded connecting rod 3 is in the shape of a long rod. Its first end is fixedly connected to the second end of the conversion head 5. Its second end, that is, the end near the double-ended threaded adjusting rod 4, is provided with an internal thread hole. The specification of its internal thread is adapted to the external thread of the first end of the double-ended threaded adjusting rod 4.

[0082] like Figure 9 and Figure 10 As shown, the double-ended threaded adjusting rod 4 is a long rod with external threads at both ends. The first end of the double-ended threaded adjusting rod 4 has a first external thread section, and the second end of the double-ended threaded adjusting rod 4 has a second external thread section. The first external thread section is threadedly connected to the internal thread of the second end of a threaded connecting rod 3, and the second external thread section is threadedly connected to the internal thread of the second end of another threaded connecting rod 3. The two threaded connecting rods 3 are located at the two ends of the double-ended threaded adjusting rod 4, respectively. By rotating the double-ended threaded adjusting rod 4, the engagement depth between the two threaded connecting rods 3 and the double-ended threaded adjusting rod 4 can be adjusted simultaneously, thereby adjusting the overall length and preload of the support rod.

[0083] The double-threaded adjusting rod 4 is also provided with an adjusting part in the middle so that the operator can use a wrench or other tools to rotate the double-threaded adjusting rod 4 for adjustment. Preferably, the external threads at both ends of the double-threaded adjusting rod 4 have opposite directions, that is, one end is a left-hand thread and the other end is a right-hand thread, so that when the double-threaded adjusting rod 4 is rotated, the two threaded connecting rods 3 can move closer or further away synchronously to achieve rapid adjustment.

[0084] The first end of another threaded connecting rod 3 is fixedly connected to the second end of another adapter 5, and the first end of another adapter 5 is fixedly connected to the first end of the thrust fastening joint 8.

[0085] In other words, the support rod is equipped with two conversion heads 5 and two threaded connecting rods 3. One conversion head 5 and one threaded connecting rod 3 are connected to the fixed joint 2 on the side of the measuring positioning plate 1, and the other conversion head 5 and the other threaded connecting rod 3 are connected to the thrust fastening joint 8 on the side of the metal fixed body. The double-headed threaded adjusting rod 4 is connected between the two threaded connecting rods 3. This symmetrical connecting rod adjustment structure allows the length of the support rod to be continuously adjusted within a certain range, thereby adapting to the installation space requirements of different types of solid rocket motors.

[0086] like Figure 17 and Figure 18 As shown, the first end of the thrust fastening connector 8, that is, the end near the adapter 5, is provided with an internal threaded hole for connecting with the external thread of the first end of the adapter 5. The second end of the thrust fastening connector 8, that is, the end near the solid rocket motor metal fixture, is provided with a U-shaped clamping head. The U-shaped clamping head has two opposing clamping arms, and a U-shaped clamping space is formed between the two clamping arms. The U-shaped clamping space is used to accommodate the exposed circumferential metal end of the solid rocket motor metal fixture. A fastening hole is provided on one clamping arm, and the threaded stud 10 passes through the fastening hole to fasten the thrust fastening connector 8 to the exposed circumferential metal end of the solid rocket motor metal fixture.

[0087] The inner surface of the U-shaped clamping head of the thrust fastening connector 8, i.e., the opposite surface of the clamping arm, can also be provided with anti-slip texture to increase the friction with the exposed circumferential metal end of the metal fixture and prevent slippage of the device during assembly. In a preferred embodiment, the height of the U-shaped clamping space of the thrust fastening connector 8 is adapted to the thickness of the exposed circumferential metal end of the solid rocket motor metal fixture, so that the exposed circumferential metal end can be tightly embedded in the U-shaped clamping space.

[0088] like Figure 21 and Figure 22As shown, the threaded head 10 is a threaded fastener with an external thread at one end. The threaded head 10 passes through the fastening hole of the U-shaped clamping head of the thrust fastening joint 8, directly clamping the exposed circumferential metal end. The thrust fastening joint 8 is then securely connected to the solid rocket motor metal fixture via a nut. On the measuring positioning plate 1 side of the support rod, the threaded head 10 passes through the fastening hole of the U-shaped clamping head of the fixed joint 2 and the through hole of the measuring positioning plate 1, securing the fixed joint 2 to the measuring positioning plate 1.

[0089] In some embodiments, such as Figure 2 As shown, two flexible adaptive adjustment mechanisms are symmetrically arranged on both sides of the support rod. One end of the flexible adaptive adjustment mechanism is fixedly connected to the measuring positioning plate 1, and the other end is fastened to the exposed circumferential metal end of the solid rocket motor metal fixture. The flexible adaptive adjustment mechanism includes a threaded connecting rod 3, a double-ended threaded adjusting rod 4, a ball joint seat 6, a ball head 7, a thrust fastening joint 8, and a threaded column head 10. The structure of the threaded connecting rod 3, the double-ended threaded adjusting rod 4, the thrust fastening joint 8, and the threaded column head 10 is the same as the structure of the corresponding components in the support rod.

[0090] like Figure 15 and Figure 16 As shown, the first end of the ball head 7 is provided with an external thread, and the second end of the ball head 7 is provided with an outer spherical structure. The first end of the ball head 7 is fixedly connected to the side of the measuring positioning plate 1. Specifically, the upper and lower parts of the side of the measuring positioning plate 1 are respectively provided with internal thread holes. The external thread of the first end of the ball head 7 is threadedly engaged with the internal thread hole and locked and fixed by a nut.

[0091] The outer spherical surface of the second end of the ball head 7 is a spherical convex surface, and its spherical radius is adapted to the spherical radius of the inner spherical surface of the first end of the ball joint seat 6. The second end of the ball head 7 is rotatably fitted into the first end of the ball joint seat 6, forming a ball joint fit. The ball joint fit allows the flexible adaptive adjustment mechanism to adapt and adjust the angle by freely rotating the ball head 7 within the ball joint seat 6 when subjected to lateral force or bending moment, avoiding stress concentration or structural damage caused by rigid connection.

[0092] like Figure 13 and Figure 14 As shown, the first end of the ball joint seat 6 is provided with an inner spherical structure, which is a spherical concave surface, for installation in conjunction with the outer spherical structure of the second end of the ball head 7. The second end of the ball joint seat 6, i.e. the bottom end face, is provided with four circumferentially distributed through holes for fixed connection with the first end of the threaded connecting rod 3. The first end of the ball joint seat 6 is also provided with an opening, the diameter of which is smaller than the diameter of the outer spherical surface of the second end of the ball head 7, so that the second end of the ball head 7 can be embedded in the inner spherical structure of the ball joint seat 6 but will not come out, forming a structure similar to a ball joint chain.

[0093] The structure of the threaded connecting rod 3 is the same as that of the threaded connecting rod 3 in the support rod. The first end of the threaded connecting rod 3 is provided with four circumferentially distributed connecting holes for fixing to the second end of the ball joint seat 6 by screws. The second end of the threaded connecting rod 3 is provided with internal threads for threaded connection to the first or second end of the double-ended threaded adjusting rod 4.

[0094] The connection method of the flexible adaptive adjustment mechanism is as follows: the first end of the ball head 7 is threadedly connected to the side of the measuring positioning plate 1; the second end of the ball head 7 is ball-jointed with the first end of the ball joint seat 6; the second end of the ball joint seat 6 is fixedly connected to the first end of the threaded connecting rod 3 by screws; the second end of the threaded connecting rod 3 is threadedly connected to the first end of the double-ended threaded adjusting rod 4; the second end of the double-ended threaded adjusting rod 4 is threadedly connected to the second end of another threaded connecting rod 3; the first end of the other threaded connecting rod 3 is fixedly connected to the second end of another ball joint seat 6; the first end of another ball joint seat 6 is ball-jointed with the second end of another ball head 7; the first end of another ball head 7 is fixedly connected to the first end of the thrust fastening joint 8; and the second end of the thrust fastening joint 8 is fastened to the exposed circumferential metal end of the solid rocket motor metal fixture through the threaded column head 10.

[0095] In some embodiments, the four through holes evenly distributed around the bottom end face of the ball joint seat 6 are countersunk through holes, the four connecting holes evenly distributed around the first end face of the threaded connecting rod 3 are blind holes, and the screw is an internal hexagon countersunk screw. After the screw passes through the countersunk through hole of the ball joint seat 6, it engages with the threaded hole of the threaded connecting rod 3 to fix the ball joint seat 6 to the first end of the threaded connecting rod 3. The head of the countersunk screw is embedded in the countersunk through hole and does not protrude from the bottom end face of the ball joint seat 6, ensuring the flatness and aesthetics of the connection.

[0096] The fixed connection between the second end of the ball joint seat 6 and the first end of the threaded connecting rod 3, as well as the fixed connection between the second end of the adapter head 5 and the first end of the threaded connecting rod 3, are both achieved by four screws.

[0097] In some embodiments, the support rod and the two flexible adaptive adjustment mechanisms form three connection points, which are respectively fastened to the exposed circumferential metal end of the solid rocket motor metal fixture through three thrust fastening joints 8. The three thrust fastening joints 8 are distributed in a triangle on the exposed circumferential metal end of the metal fixture, forming a triangular stable support structure.

[0098] The triangular support structure has good geometric stability and can effectively resist external forces from all directions, ensuring that the measuring positioning plate 1 maintains a stable spatial position during assembly. At the same time, since both flexible adaptive adjustment mechanisms are equipped with ball joint structures, when the solid rocket motor metal fixture undergoes slight displacement or deflection during assembly, the ball joint structure can adaptively adjust its angle to avoid excessive internal stress in the support rod or flexible adaptive adjustment mechanism, thereby ensuring that the target ball position on the measuring positioning plate 1 will not change unexpectedly due to external forces.

[0099] The adjustable function of the double-threaded adjusting rod 4 further enhances the adaptability of the device. During installation, the operator can rotate the double-threaded adjusting rod 4 to continuously adjust the lengths of the two flexible adaptive adjustment mechanisms and the support rod within a preset range, thereby accommodating the installation size differences of different models of solid rocket motor metal mounting bodies. During use, the double-threaded adjusting rod 4 also provides a pre-tightening effect. By applying an appropriate pre-tightening force, gaps between the threaded connections are eliminated, improving the rigidity and stability of the entire support structure.

[0100] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0101] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A digital assembly positioning measurement feedback method for solid rocket motor nozzles, characterized in that, include: Step 100: Install the positioning measurement feedback device on the external structure of the solid rocket motor metal fixture, and fasten it to the exposed circumferential metal end of the solid rocket motor metal fixture through three thrust fastening joints. Adjust the double-threaded adjusting rod to provide preload force for the two flexible adaptive adjustment mechanisms to form a triangular stable support structure. Step 200: Use a laser tracker to measure the first spatial coordinate set of the four target balls on the positioning plate in the measurement coordinate system, and the coordinates of the feature points of the assembly surface on the solid rocket motor metal fixed body in the measurement coordinate system. Based on the feature points of the assembly surface, construct the original local coordinate system of the nozzle, and transform the first spatial coordinate set of the four target balls to the original local coordinate system of the nozzle to obtain the calibration constants and store them in the database. Step 300: Construct the combustion chamber reference coordinate system as a fixed world reference, define the nozzle follower coordinate system as a rigid body fixed coordinate system, establish the coordinate transformation relationship between the first spatial coordinate set and the original local coordinate system of the nozzle, determine the rotation matrix R and translation matrix T for the transformation from the measurement coordinate system to the nozzle follower coordinate system, and describe the six-dimensional pose of the nozzle follower coordinate system relative to the combustion chamber reference coordinate system through the homogeneous transformation matrix. Step 400: During the solid rocket motor docking and assembly process, a laser tracker is used to measure the second spatial coordinate set of the four target spheres in the measurement coordinate system in real time; Step 500: Based on the second spatial coordinate set, the rotation matrix R, and the translation matrix T, calculate the real-time six-dimensional pose of the nozzle in the combustion chamber reference coordinate system by combining the calibration constant. Step 600: Based on the deviation between the real-time six-dimensional pose and the target assembly pose parameters, output assembly guidance data, adjust the pose of the solid rocket motor, and complete the digital assembly control.

2. The digital assembly positioning measurement feedback method for solid rocket motor nozzles as described in claim 1, characterized in that, The construction of the nozzle's original local coordinate system based on the assembly surface feature points specifically includes: The least squares fit is performed on the planar features in the feature points of the assembly surface to obtain the assembly reference plane. The normal vector of the assembly reference plane is defined as the local X-axis, with the direction pointing to the surface to be assembled being the positive direction. The quadrant points among the feature points of the assembly surface are taken as local features, and the local Y-axis is defined by the vector direction from the outer circle center of the assembly reference plane to the quadrant point. The local Z-axis is calculated using the cross product of the right-hand coordinate system. The origin of the coordinate system is then used as the center of the hole axis theory to complete the construction of the original local coordinate system of the nozzle.

3. The digital assembly positioning measurement feedback method for solid rocket motor nozzles as described in claim 1, characterized in that, In step 500, the formula for the inversion calculation is expressed as follows: ； in, The matrix formed by the second spatial coordinate set. Rotation matrix The inverse matrix, It is a translation matrix. The real-time coordinate set in the original local coordinate system of the nozzle obtained by inversion calculation, combined with the calibration constant, will The position of the nozzle follower coordinate system is mapped to the real-time six-dimensional pose of the combustion chamber reference coordinate system.

4. The digital assembly positioning measurement feedback method for solid rocket motor nozzles as described in claim 1, characterized in that, The target assembly pose parameters include the nozzle axis direction vector, the position of the nozzle end face center point, and the rotation angle of the nozzle around the axis. The assembly guidance data includes the deviation value of each parameter direction and the adjustment direction indication.

5. A digital assembly positioning measurement feedback device for a solid rocket motor nozzle, used to implement the digital assembly positioning measurement feedback method for a solid rocket motor nozzle as described in any one of claims 1 to 4, characterized in that, Includes a measuring positioning plate, support rod, and two flexible adaptive adjustment mechanisms: The measuring positioning plate has a through hole in the middle and four measuring target seats on the front. Target balls are installed on the measuring target seats. The measuring positioning plate is used to cooperate with the laser tracker through the target balls to establish a measurable spatial positioning reference outside the nozzle. One end of the support rod is fixedly connected to the through hole, and the other end of the support rod is fastened to the exposed circumferential metal end of the solid rocket motor metal fixture. The support rod is used to fix and support the measuring positioning plate on the solid rocket motor metal fixture and to transmit the load and torque during the measurement process. Two flexible adaptive adjustment mechanisms are symmetrically arranged on both sides of the support rod. One end of the flexible adaptive adjustment mechanism is fixedly connected to the measuring positioning plate, and the other end of the flexible adaptive adjustment mechanism is fastened to the exposed circumferential metal end of the solid rocket motor metal fixture. The flexible adaptive adjustment mechanism is used to adaptively adjust the angle and apply preload, so that the support rod and the two flexible adaptive adjustment mechanisms together form a triangular stable support structure to ensure the spatial position stability of the target ball during assembly.

6. The digital assembly positioning measurement feedback device for solid rocket motor nozzles as described in claim 5, characterized in that, The support rod includes a fixed joint, an adapter, a threaded connecting rod, a double-ended threaded adjusting rod, a thrust fastening joint, and a threaded post. The first end of the fixed joint is disposed at the through hole of the measuring positioning plate, and is used to initially position and connect the support rod to the measuring positioning plate; The first end of the adapter is fixedly connected to the second end of the fixed connector, and the second end of the adapter is fixedly connected to the first end of the threaded connecting rod. The second end of the threaded connecting rod is provided with an internal thread, and the first end of the double-ended threaded adjusting rod is provided with an external thread. The second end of the threaded connecting rod is threadedly connected to the first end of the double-ended threaded adjusting rod. The second end of the double-ended threaded adjusting rod is provided with an external thread and is connected to the internal thread of the second end of another threaded connecting rod. The first end of the other threaded connecting rod is connected to the second end of another adapter. The double-ended threaded adjusting rod is used to adjust the engagement depth of the two threaded connecting rods at both ends by rotation, so as to realize the overall length adjustment of the support rod and the application of preload. The first end of the other adapter is fixedly connected to the first end of the thrust fastening joint, and the second end of the thrust fastening joint is located at the exposed circumferential metal end of the solid rocket motor metal fixture. Both the first end of the fixed joint and the second end of the thrust fastening joint are provided with U-shaped clamping heads, and a fastening hole is provided on one side of the U-shaped clamping head. The U-shaped clamping head is used to clamp and fix the exposed circumferential metal end of the measuring positioning plate and the solid rocket motor metal fixing body. The threaded head passes through the fastening hole, fastening the fixing joint to the measuring positioning plate, and simultaneously fastening the thrust fastening joint to the exposed circumferential metal end of the solid rocket motor metal fixing body. The threaded head is used to achieve quick assembly and disassembly and reliable locking.

7. The digital assembly positioning measurement feedback device for solid rocket motor nozzles as described in claim 6, characterized in that, The first end of the adapter is provided with an external thread, and the second end of the fixed connector and the first end of the thrust fastening connector are both provided with internal thread holes. The first end of the adapter is threadedly connected to the second end of the fixed connector and the first end of the thrust fastening connector, and is locked and fixed by a hexagonal nut. The second end of the converter head is provided with four circumferentially distributed connecting holes, and the first end of the threaded connecting rod is fixedly connected to the second end of the converter head by passing through the connecting holes with screws.

8. The digital assembly positioning measurement feedback device for solid rocket motor nozzles as described in claim 5, characterized in that, The flexible adaptive adjustment mechanism includes a threaded connecting rod, a double-ended threaded adjusting rod, a ball joint seat, a ball head, a thrust fastening joint, and a threaded column head; The first end of the ball head is fixedly connected to the side of the measuring positioning plate, and the second end of the ball head is engaged with the first end of the ball joint seat. The ball head is used to transmit the constraint force of the measuring positioning plate to the ball joint seat and achieve adaptive adjustment of the angle through spherical engagement. The second end of the ball joint seat is fixedly connected to the first end of the threaded connecting rod, the second end of the threaded connecting rod is threadedly connected to the first end of the double-ended threaded adjusting rod, the second end of the double-ended threaded adjusting rod is connected to the second end of another threaded connecting rod, and the first end of another threaded connecting rod is fixedly connected to the second end of another ball joint seat. The first end of another ball joint seat is connected to the second end of another ball head, and the first end of another ball head is fixedly connected to the first end of the thrust fastening joint. The ball joint seat and the ball head are used to adaptively adjust the angle when the solid rocket motor metal fixed body is displaced or deflected, so as to avoid stress concentration caused by rigid connection. The second end of the thrust fastening joint is fastened to the exposed circumferential metal end of the solid rocket motor metal fixture via the threaded post, for detachably fixing the flexible adaptive adjustment mechanism to the solid rocket motor metal fixture.

9. The digital assembly positioning measurement feedback device for solid rocket motor nozzles as described in claim 8, characterized in that, The second end of the ball joint seat is provided with four through holes evenly distributed in a circumferential direction, and the first end of the threaded connecting rod is provided with four threaded holes evenly distributed in a circumferential direction. Four screws pass through the four through holes of the ball joint seat and are threaded into the four threaded holes of the threaded connecting rod to fix the ball joint seat to the first end of the threaded connecting rod.

10. The digital assembly positioning measurement feedback device for solid rocket motor nozzles as described in claim 9, characterized in that, The first end of the ball head is provided with an external thread, and the first end of the ball head is threadedly connected to the side of the measuring positioning plate and the first end of the thrust fastening joint, and is locked by a nut; The first end of the ball joint seat is provided with an inner spherical structure, and the second end of the ball head is provided with an outer spherical structure. The second end of the ball head is rotatably fitted into the first end of the ball joint seat to form a ball joint engagement. The ball joint engagement is used to realize adaptive adjustment of angular displacement in at least two degrees of freedom, so that the flexible adaptive adjustment mechanism can adapt to the positional changes of the solid rocket motor metal fixture during assembly, while maintaining the stability of the triangular stable support structure.

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