A method and system for predicting the yarn trajectory in the weaving process of a special-shaped structure core mold

Abstract

The present invention relates to the technical field of weaving, and specifically to a method for predicting the yarn trajectory in the weaving process of a special-shaped structure core mold. The method includes the following steps: calculating the movement trajectories of the dual robots that tow the core mold during the weaving process; obtaining the movement trajectories of the spindles on the weaving machine according to the movement trajectories of the dual robots; simulating the process of the yarn forming a fabric on the core mold according to the variation law of the movement trajectories of the spindles on the weaving machine, and determining whether the yarn lands on the surface of the core mold; if the yarn has landed on the surface of the core mold, updating the position of the yarn landing point according to the constraint conditions of the yarn trajectory. By establishing a prediction model for the yarn trajectory in the weaving process of a special-shaped structure core mold, the present invention predicts the change of the yarn landing point during the weaving process, calculates the distribution of the yarn on the surface of the core mold and the size of the weaving angle of the preform, and predicts the yarn trajectory in the weaving process of the special-shaped structure core mold, thereby improving the weaving efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of braiding, and particularly to a method and system for predicting the yarn trajectory in the braiding process of a core mold with a special-shaped structure. Background Art

[0002] The braiding technique is an important process for weaving composite preforms. In the fields of automobile manufacturing, medical devices, aerospace, etc., braided composites have been widely used. However, there are still problems that need to be urgently solved in the industry, such as large braiding errors and uneven coverage for large-sized components.

[0003] For a core mold with a large-sized special-shaped structure, due to the complexity of its structure, it is necessary to use robots to tow the core mold to braid along a certain trajectory. The trajectory affects important process parameters such as the braiding angle and coverage rate of the fabric, and directly affects the mechanical properties of the composite material finished product. Changing the towing speed and the main machine speed during the braiding process or replacing the size of the guide ring will form composite preforms with different properties. Therefore, a yarn trajectory prediction model is needed to predict the distribution of yarn on the surface of the core mold under different braiding conditions, which can improve the production efficiency in actual production. Summary of the Invention

[0004] Aiming at the deficiencies of the existing methods and the requirements of practical applications, in order to achieve accurate prediction of the yarn trajectory in the braiding process of a core mold with a special-shaped structure, the present invention provides a method for predicting the yarn trajectory in the braiding process of a core mold with a special-shaped structure. The method includes the following steps: calculating the movement trajectories of the double robots that tow the core mold during the braiding process, where the double robots include a first robot and a second robot; obtaining the movement trajectories of the spindles on the braiding machine according to the movement trajectories of the double robots; simulating the process of the yarn forming a fabric on the core mold according to the variation law of the movement trajectories of the spindles on the braiding machine, and determining whether the yarn falls on the surface of the core mold; if the yarn has fallen on the surface of the core mold, updating the position of the yarn landing point according to the constraint conditions of the yarn trajectory. Through the method for predicting the yarn trajectory in the braiding process of a core mold with a special-shaped structure, the present invention predicts the change of the yarn landing point during the braiding process, calculates the distribution of the yarn on the surface of the core mold and the size of the braiding angle of the preform, predicts the yarn trajectory in the braiding process of a core mold with a special-shaped structure, improves the braiding efficiency, and under the same conditions, improves the mechanical properties of the braided composite material.

[0005] Optionally, the motion trajectories of the dual robots for pulling the core mold during the computational braiding process include the following steps: In a three-dimensional motion space, establish a base coordinate system and a tool coordinate system for the first robot and a base coordinate system and a tool coordinate system for the second robot respectively; discretize the core mold to obtain multiple discrete core molds, and describe the center line and the shape of the core mold in the tool coordinate system of the first robot and the tool coordinate system of the second robot; calculate the trajectory of the first robot and ensure that any section of the discrete core mold passes through the braiding plane vertically; use the geometric constraint conditions of the positional relationship in the base coordinate system of the first robot and the base coordinate system of the second robot to calculate the trajectory of the second robot. The present invention determines the motion trajectories of the spindles on the braiding machine by calculating the motion trajectories of the dual robots for pulling the core mold during the braiding process, which is beneficial to the prediction of the yarn trajectories during the braiding process.

[0006] Optionally, obtaining the motion trajectories of the spindles on the braiding machine according to the motion trajectories of the dual robots includes: establishing a three-dimensional coordinate system on the end face of the core mold; taking the motion trajectories of the dual robots as the motion trajectories of the core mold; according to the relative motion relationship, converting the process of the core mold passing through the braiding plane during the braiding process into the braiding plane and the braiding machine passing through the core mold, so as to obtain the motion trajectories of the spindles on the braiding machine. The present invention simplifies the calculation process of yarn trajectory prediction by converting the process of the core mold passing through the braiding plane into the process of the braiding plane and the braiding machine passing through the core mold through the relative motion relationship during the braiding process.

[0007] Optionally, the motion trajectories of the spindles on the braiding machine satisfy the following formula:

[0008]

[0009] where q i,j is the spatial position of the i-th carrier at time T j ; Q j is the discrete point on the center line; Rot is the rotation matrix; t j is the unit tangent vector corresponding to Q j ; z m is the direction vector corresponding to the z-axis in the core mold end face coordinate system; r sp is the radius of the spool outlet plane; θ i,j is the angular position of the i-th carrier on the braiding machine at time T j .

[0010] Optionally, determining whether the yarn has landed on the surface of the mandrel includes: obtaining the intersection point of the yarn and the guide ring on the knitting machine according to geometric relationships; determining whether the yarn has landed on the surface of the mandrel based on the geometric positions of the intersection point of the yarn and the guide ring on the knitting machine, the known landing point, and the normal vector, where the known landing point is the known landing point of the yarn on the upper surface of the mandrel, and the normal vector is the normal vector pointing to the outside of the mandrel on the triangular patch where the known landing point is located.

[0011] Optionally, the condition for determining whether the yarn has landed on the surface of the mandrel satisfies the following formula:

[0012] n M ·(g i,j -p i,j )≤0

[0013] where n M is the normal vector pointing to the outside of the mandrel on the triangular patch where the yarn landing point is located; g i,j is the spatial position of the intersection point of the i-th yarn and the guide ring on the knitting machine at time T j , and p i,j is the spatial position of the i-th yarn landing point at time T j .

[0014] Optionally, the method for predicting the yarn trajectory during the knitting process of the profiled mandrel includes: setting the constraint conditions for the yarn trajectory, where the constraint conditions are:

[0015] Define the triangular patch where the yarn landing point is located as F, and the trajectory direction of the yarn on the triangular patch F is the direction of the projection of the vector (g i,j -p i,j ) on the triangular patch F, and the length is the length from the known landing point to the boundary of the triangular patch.

[0016] Optionally, if the yarn has landed on the surface of the mandrel, then update the position of the yarn landing point according to the constraint conditions of the yarn trajectory, satisfying the following formula:

[0017]

[0018] where p' is the spatial position after the landing point is updated; p is the spatial position of the known landing point; (g i,j -p i,j ) F is the projection of the yarn on the triangular patch F; M F and M' F are the two vertices corresponding to the edge pointed by the yarn on the triangular patch F; n d is the normal vector of the plane formed by the edge line pointed by the yarn on the triangular patch F and the normal vector n F of the triangular patch F, nd The expression is as follows:

[0019]

[0020] Optionally, the method for predicting the yarn trajectory in the braiding process of the special-shaped structure core mold further includes: calculating the braiding angle of the preform after braiding; the calculation of the braiding angle of the preform after braiding satisfies the following formula:

[0021]

[0022] where θ is the braiding angle, which is the angle formed by a single yarn and the center line of the core mold; R g is the radius of the guide ring on the braiding machine; r is the radius of the core mold; H is the linear distance between the braiding plane and the plane of the guide ring on the braiding machine.

[0023] In a second aspect, to efficiently execute the method for predicting the yarn trajectory in the braiding process of the special-shaped structure core mold provided by the present invention, the present invention further provides a system for predicting the yarn trajectory in the braiding process of the special-shaped structure core mold. The system includes a processor, an input device, an output device, and a memory. The processor, input device, output device, and memory are interconnected. Among them, the memory is used to store a computer program, and the computer program includes program instructions. The processor is configured to call the program instructions to execute the method for predicting the yarn trajectory in the braiding process of the special-shaped structure core mold as described in the first aspect of the present invention. The system for predicting the yarn trajectory in the braiding process of the special-shaped structure core mold of the present invention has a compact structure and stable performance, and can stably execute the method for predicting the yarn trajectory in the braiding process of the special-shaped structure core mold provided by the present invention, improving the overall applicability and practical application ability of the present invention. Description of the Drawings

[0024] Figure 1 is a flowchart of the method for predicting the yarn trajectory in the braiding process of the special-shaped structure core mold according to an embodiment of the present invention;

[0025] Figure 2 is a flowchart of calculating the movement trajectories of the dual robots for towing the core mold during the braiding process according to an embodiment of the present invention;

[0026] Figure 3 is a schematic diagram of the geometric relationship among the core mold, the yarn, and the guide ring on the braiding machine according to an embodiment of the present invention;

[0027] Figure 4 is a schematic diagram of the yarn trajectory prediction process according to an embodiment of the present invention;

[0028] Figure 5 is a comparison diagram of the predicted yarn structure and the actual structure according to an embodiment of the present invention;

[0029] Figure 6Comparison chart of fabric expected values, actual values, and predicted values at different positions in the embodiments of the present invention;

[0030] Figure 7 Structural diagram of the yarn trajectory prediction system for the weaving process of the special-shaped structure core mold provided in the embodiments of the present invention. Detailed implementation manners

[0031] The specific embodiments of the present invention will be described in detail below. It should be noted that the embodiments described here are only for illustrative purposes and do not limit the present invention. In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to those of ordinary skill in the art that the present invention does not have to be practiced with these specific details. In other instances, well-known circuits, software, or methods have not been specifically described to avoid obscuring the present invention.

[0032] Throughout the specification, the reference to "one embodiment", "an embodiment", "one example", or "an example" means that the specific features, structures, or characteristics described in connection with the embodiment or example are included in at least one embodiment of the present invention. Thus, the phrases "in one embodiment", "in an embodiment", "one example", or "an example" appearing throughout the specification do not necessarily all refer to the same embodiment or example. Additionally, the specific features, structures, or characteristics may be combined in any suitable combination and / or sub-combination in one or more embodiments or examples. Further, those of ordinary skill in the art should understand that the diagrams provided herein are for illustrative purposes only and are not necessarily drawn to scale.

[0033] In an alternative embodiment, please refer to Figure 1 , Figure 1 which is the flowchart of the yarn trajectory prediction method for the weaving process of the special-shaped structure core mold provided in the embodiments of the present invention. As shown in Figure 1 , the yarn trajectory prediction method for the weaving process of the special-shaped structure core mold includes the following steps:

[0034] S1. Calculate the motion trajectories of the dual robots that tow the core mold during the weaving process. The dual robots include a first robot and a second robot.

[0035] Specifically, please refer to Figure 2, in an optional embodiment, the motion trajectories of the dual robots that pull the core mold during the calculation of the braiding process include the following steps: In a three-dimensional motion space, establish a base coordinate system and a tool coordinate system for the first robot and a base coordinate system and a tool coordinate system for the second robot respectively; discretize the core mold to obtain multiple discrete core molds, and describe the center line and the shape of the core mold in the tool coordinate system of the first robot and the tool coordinate system of the second robot; calculate the trajectory of the first robot and ensure that any section of the discrete core mold passes through the braiding plane vertically; use the geometric constraint conditions of the positional relationship in the base coordinate system of the first robot and the base coordinate system of the second robot to calculate the trajectory of the second robot.

[0036] For the process of the dual robots jointly clamping a core mold for braiding, it is necessary to solve the data of the tool center points (TCP) of the two robots in their respective base coordinate systems. The data of the tool center point (TCP) includes six values of x, y, z, a, b, and c, where x, y, and z are the position information of the origin of the tool coordinate system in the base coordinate system, and a, b, and c represent the angles by which the tool coordinate system rotates around the z-axis, y-axis, and x-axis of the base coordinate system. Record the data of the tool center points (TCP) corresponding to the two robots respectively to obtain the motion trajectories of the dual robots that pull the core mold during the braiding process.

[0037] S2. Obtain the motion trajectories of the spindles on the braiding machine according to the motion trajectories of the dual robots.

[0038] Specifically, in this embodiment, the obtaining of the motion trajectories of the spindles on the braiding machine according to the motion trajectories of the dual robots includes: establishing a three-dimensional coordinate system on the end face of the core mold; taking the motion trajectories of the dual robots as the motion trajectories of the core mold; according to the relative motion relationship, converting the process that the core mold passes through the braiding plane during the braiding process into the braiding plane and the braiding machine passing through the core mold to obtain the motion trajectories of the spindles on the braiding machine. Among them, the core mold end face coordinate system {x m , y m , z m} is a fixed coordinate system.

[0039] In an optional embodiment, the motion trajectories of the spindles on the braiding machine satisfy the following formula:

[0040]

[0041] where q i,j is the spatial position of the i-th carrier at time T j ; Q j is the discrete point on the center line; Rot is the rotation matrix; t j is Q jThe corresponding unit tangent vector; z m Is the direction vector corresponding to the z-axis in the coordinate system of the core mold end face; r sp Is the radius of the spool outlet plane; θ i,j Is T j The angular position of the i-th carrier on the knitting machine at time T. Specifically, the movement trajectory of the spindles on the knitting machine is a spatial helix, and its center line is determined by the movement trajectories of the two robots that pull the core mold during the knitting process.

[0042] S3. Simulate the process of the yarn forming a fabric on the core mold according to the change rule of the movement trajectory of the spindles on the knitting machine, and judge whether the yarn falls on the surface of the core mold.

[0043] Specifically, in an optional embodiment, please refer to Figure 3 , Figure 3 Is a schematic diagram of the geometric relationship among the core mold, the yarn, and the guide ring on the knitting machine. The judgment of whether the yarn falls on the surface of the core mold includes: obtaining the intersection point of the yarn and the guide ring on the knitting machine according to the geometric relationship; determining whether the yarn has fallen on the surface of the core mold according to the geometric positions of the intersection point of the yarn and the guide ring on the knitting machine, the known landing point, and the normal vector, where the known landing point is the known landing point of the yarn on the upper surface of the core mold, and the normal vector is the normal vector pointing to the outside of the core mold on the triangular patch where the known landing point is located. Further, process the core mold data, read the three-dimensional model in STL format, and obtain the spatial position information of the core mold surface in the core mold end face coordinate system.

[0044] Furthermore, in an optional embodiment, the condition for judging whether the yarn falls on the surface of the core mold satisfies the following formula:

[0045] n M ·(g i,j -p i,j )≤0

[0046] Where n M Is the normal vector pointing to the outside of the core mold on the triangular patch where the yarn landing point is located; g i,j Is the spatial position of the intersection point of the i-th yarn and the guide ring on the knitting machine at time T j , p i,j Is the spatial position of the i-th yarn landing point at time T j .

[0047] S4. If the yarn has fallen on the surface of the core mold, update the position of the yarn landing point according to the constraint conditions of the yarn trajectory.

[0048] Specifically, in an alternative embodiment, the method for predicting the yarn trajectory during the weaving process of the profiled structure core mold includes: setting the constraint conditions for the yarn trajectory, where the constraint conditions are:

[0049] Define the triangular patch where the yarn landing point is located as F, and the trajectory direction of the yarn on the triangular patch F is the direction of the projection of the vector (g i,j -p i,j ) on the triangular patch F, and the length is the length from the known landing point to the boundary of the triangular patch.

[0050] Furthermore, in an alternative embodiment, if the yarn has landed on the surface of the core mold, the position of the yarn landing point is updated according to the constraint conditions of the yarn trajectory, and the following formula is satisfied:

[0051]

[0052] Where p′ is the spatial position after the landing point is updated; p is the spatial position of the known landing point; (g i,j -p i,j ) F is the projection of the yarn on the triangular patch F; M F and M′ F are the two vertices corresponding to the edge where the yarn points on the triangular patch F; n d is the normal vector of the plane formed by the edge line where the yarn points on the triangular patch F and the normal vector n F of the triangular patch F, and the expression of n d is as follows:

[0053]

[0054] If the yarn has not landed on the surface of the core mold, the position of the yarn landing point is not updated. The spindle on the knitting machine continues to move one step according to the motion trajectory, and then the position of the yarn landing point is judged until the judgment result is that the yarn has landed on the surface of the core mold, and the position of the yarn landing point is updated again.

[0055] In another alternative embodiment, the method for predicting the yarn trajectory during the weaving process of the profiled structure core mold further includes: calculating the weaving angle of the woven preform; calculating the weaving angle of the woven preform, and the following formula is satisfied:

[0056]

[0057] Where θ is the weaving angle, which is the angle formed by a single yarn and the center line of the core mold; R g is the radius of the guide ring on the knitting machine; r is the radius of the core mold; H is the linear distance between the weaving plane and the plane of the guide ring on the knitting machine.

[0058] Specifically, during the braiding process, the braiding machine itself carries multiple groups of spindles and makes approximate circular motions in the clockwise and counterclockwise directions along the winding track of the chassis at a specified rotational speed. The dual robots hold the mandrel and continuously advance according to the calculated trajectory and the set speed. Under such a cooperative effect, the yarn starts from the spindles, passes through the guiding rings, and finally covers the surface of the mandrel to form a composite preform. During the stable braiding process, the braiding angle can also be calculated based on the traction speed of the robot and the speed of the main body of the braiding machine. The relationship is as follows:

[0059]

[0060] Among them, ω is the speed of the main body of the braiding machine, that is, the angular velocity of the spindle movement; V is the speed of the traction device holding the mandrel movement.

[0061] It should be understood that according to the continuity of the circular braiding process, the trajectory prediction can be performed simultaneously for all the yarns during the braiding process. The prediction process of the yarn trajectory is as Figure 4 shown.

[0062] It should also be understood that the method for predicting the yarn trajectory in the braiding process of the special-shaped structure mandrel proposed by the present invention is based on the following assumptions: ignoring the frictional force and the interaction force between the yarns and between the yarns and the braiding ring; ignoring the yarn thickness; ignoring the winding movement of the yarn carrier on the chassis during the braiding process; ignoring the yarn tension fluctuation during the braiding process.

[0063] The method for predicting the yarn trajectory in the braiding process of the special-shaped structure mandrel of the present invention can accurately calculate the distribution of the yarns on the surface of the mandrel and the size of the braiding angle, and can predict the yarn trajectory during the braiding process according to any robot trajectory and any shaped mandrel.

[0064] Specifically, to verify the accuracy of the yarn trajectory prediction method for the weaving process of the special-shaped structure mandrel, through weaving experiments, the results calculated by the yarn trajectory prediction method are compared with the actual woven fabric, and the applicability of the yarn trajectory prediction method for the weaving process of the special-shaped structure mandrel is analyzed. At the same time, the weaving angles of the preform are measured, and the deviation between the measured value and the expected value is compared. The calculation process is analyzed using Matlab R2020b software on a computer equipped with a CPU of AMD R7-4800H, a GPU of GeForce RTXTM 2060, 16GB of RAM, and a Windows10 operating system. The experimental equipment includes a large ring weaving machine and two six-degree-of-freedom industrial robots. Among them, the ring weaving machine includes 240 spindles, and each spindle carries a yarn bobbin for weaving. The motion system of the weaving machine consists of 4 servo motors, 2 vibration motors, and their controllers. The robots are KUKA six-degree-of-freedom industrial robots KR 250R2700-2. It should be understood that the experimental equipment includes but is not limited to the above equipment, and can be selected according to the actual situation. The woven preform is measured. The weaving angle is obtained by measuring the angle between a single yarn and the axis using a vernier angle gauge at non-bending positions. At bending positions, it is difficult to use a vernier angle gauge, so an electronic digital display angle gauge is used to measure the included angle between two intertwined yarns and then take half to obtain the weaving angle. The fabric structure simulated by the yarn trajectory prediction method for the weaving process of the special-shaped structure mandrel is as Figure 5 shown. It can be seen that when the cross-section of the mandrel does not change, such as Figure 5 (a) and (c) in it, the weaving angle is relatively stable; when the cross-sectional area changes, the weaving angle also changes to a certain extent, such as Figure 5 (b) and (d) in it. At the same time, the measured values and predicted values of the fabric weaving angles are compared as Figure 6 shown. As can be seen from Figure 6 it, the weaving is relatively stable at non-bending positions of the cross-section. The errors between the measured values and the predicted values and between the measured values and the expected values are both small, and the error values are within ±3°. At the bending variable cross-section, the complexity of the mandrel structure makes the weaving in an unstable weaving stage. Due to factors such as the interaction between yarns, the error between the measured values and the predicted values is within ±5°, and the error between the measured values and the expected values is within ±7°. Therefore, the yarn trajectory prediction method for the weaving process of the special-shaped structure mandrel proposed by the present invention can accurately predict the trajectory of the yarn during the weaving process of the special-shaped mandrel structure, calculate the distribution of the yarn on the surface of the mandrel and the size of the weaving angle, improve the weaving efficiency, and under the same conditions, improve the mechanical properties of the woven composite material.

[0065] Please refer to Figure 7, in an optional embodiment, to efficiently execute the yarn trajectory prediction method for the knitting process of a special-shaped structure core mold provided by the present invention, the present invention also provides a yarn trajectory prediction system for the knitting process of a special-shaped structure core mold. The system includes a processor, an input device, an output device, and a memory. The processor, input device, output device, and memory are interconnected. Among them, the memory is used to store a computer program, and the computer program includes program instructions. The processor is configured to call the program instructions to execute the specific steps of the related embodiments of the yarn trajectory prediction method for the knitting process of a special-shaped structure core mold provided by the present invention. The yarn trajectory prediction system for the knitting process of a special-shaped structure core mold of the present invention has a complete, objective, and stable structure, can efficiently execute the yarn trajectory prediction method for the knitting process of a special-shaped structure core mold of the present invention, and improves the overall applicability and practical application ability of the present invention.

[0066] 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 them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the various embodiments of the present invention, and they should all be covered by the scope of the claims and the description of the present invention.

Claims

1. A method for predicting the yarn trajectory in the weaving process of a special-shaped structure core mold, characterized in that, Including the following steps: Calculating the motion trajectories of the dual robots for pulling the mandrel during the braiding process, where the dual robots include a first robot and a second robot; Deriving the motion trajectories of the spindles on the braiding machine based on the motion trajectories of the dual robots; Simulating the process of the yarn forming a fabric on the mandrel according to the variation law of the motion trajectories of the spindles on the braiding machine, and determining whether the yarn lands on the surface of the mandrel; If the yarn has landed on the surface of the mandrel, updating the position of the yarn landing point according to the constraint conditions of the yarn trajectory; The constraint conditions are: Define the triangular patch where the yarn landing point is located as F, and the trajectory direction of the yarn on the triangular patch F is the vector The projection direction on the triangular patch F, and the length is the length from the known landing point to the boundary of the triangular patch F; The determination of whether the yarn lands on the surface of the mandrel includes: Obtaining the intersection points of the yarn and the guide rings on the braiding machine according to geometric relationships; Determining whether the yarn has landed on the surface of the mandrel based on the geometric positions of the intersection points of the yarn and the guide rings on the braiding machine, the known landing point, and the normal vector, where the known landing point is the known landing point of the yarn on the upper surface of the mandrel, and the normal vector is the normal vector pointing outside the mandrel on the triangular patch F where the known landing point is located; The condition for determining whether the yarn lands on the surface of the mandrel satisfies the following formula: Among them, is the normal vector pointing to the outside of the mandrel on the triangular patch F where the yarn landing point is located; is the -th spatial position of the intersection point of the -th yarn and the guide ring on the knitting machine at time j, is the spatial position of the -th yarn landing point at time j.

2. The method for predicting the yarn trajectory in the weaving process of the special-shaped structure core mold according to claim 1, wherein The calculation of the motion trajectories of the dual robots for pulling the mandrel during the braiding process includes the following steps: In a three-dimensional motion space, respectively establishing a base coordinate system and a tool coordinate system for the first robot and a base coordinate system and a tool coordinate system for the second robot; Performing discretization processing on the mandrel to obtain multiple discrete mandrels, and describing the center line and the shape of the mandrel in the tool coordinate system of the first robot and the tool coordinate system of the second robot; Calculating the trajectory of the first robot and ensuring that any segment of the discrete mandrel passes vertically through the braiding plane; Calculating the trajectory of the second robot using the geometric constraint conditions of the position relationship in the base coordinate system of the first robot and the base coordinate system of the second robot.

3. The method for predicting the yarn trajectory in the weaving process of the special-shaped structure core mold according to claim 1, characterized in that, The derivation of the motion trajectories of the spindles on the braiding machine based on the motion trajectories of the dual robots includes: Establishing a three-dimensional coordinate system on the end face of the mandrel; Taking the motion trajectories of the dual robots as the motion trajectories of the mandrel; According to the relative motion relationship, converting the process of the mandrel passing through the braiding plane during the braiding process into the braiding plane and the braiding machine passing through the mandrel, and deriving the motion trajectories of the spindles on the braiding machine.

4. The method for predicting the yarn trajectory in the weaving process of the special-shaped structure core mold according to claim 3, wherein, The motion trajectories of the spindles on the braiding machine satisfy the following formula: Among them, is the spatial position of the th spindle at time j; is a discrete point on the core mold center line; is the rotation matrix; is corresponding unit tangent vector; is in the core mold end face coordinate system axis corresponding direction vector; is the radius of the spool outlet plane; is the angular position of the th spindle on the knitting machine at time j.

5. The method for predicting the yarn trajectory in the weaving process of the special-shaped structure core mold according to claim 1, wherein If the yarn has landed on the surface of the mandrel, updating the position of the yarn landing point according to the constraint conditions of the yarn trajectory, which satisfies the following formula: Among them, is the spatial position after the landing point is updated; is the spatial position of the known landing point; is the projection of the yarn on the triangular patch F; and are the two vertices corresponding to the edge pointed by the yarn on the triangular patch F; is the normal vector of the plane formed by the edge line pointed by the yarn on the triangular patch F and the normal vector of the triangular patch F, The expression of is as follows: 。 6. The method for predicting the yarn trajectory in the weaving process of the special-shaped structure core mold according to claim 1, characterized in that, The method for predicting the yarn trajectory during the braiding process of the profiled mandrel further includes: Calculating the braiding angle of the preform after braiding; The calculation of the braiding angle of the preform after braiding satisfies the following formula: Among them, is the braiding angle, which is the angle formed by a single yarn and the central axis of the core mold; is the radius of the guide ring on the braiding machine; is the radius of the core mold; is the linear distance between the braiding plane and the plane of the guide ring on the braiding machine.

7. A yarn trajectory prediction system for the weaving process of a special-shaped structure core mold, characterized in that, The system includes a processor, an input device, an output device, and a memory. The processor, input device, output device, and memory are interconnected. Among them, the memory is used to store a computer program, and the computer program includes program instructions. The processor is configured to call the program instructions to execute the method for predicting the yarn trajectory in the weaving process of the special-shaped structure core mold according to any one of claims 1-6.

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