A continuous cable conductive structure on-line room temperature printing method and system

Abstract

The application discloses a kind of continuous cable conductive structure online room temperature printing method and system, belong to cable manufacturing technical field, it includes obtaining outer contour survey point cloud, registration and fitting are carried out, generate three-dimensional center path curve and carry out decomposition, construct space normal field, generate cable surface space pose data, mapping and compensation are carried out to standard geometric model, generate online printing path trajectory;Room temperature solidification conductive ink is extruded to the surface of moving cable along online printing path trajectory, forms wet state conductive pattern, applies forced environmental condition, accelerates the crosslinking process of silicone rubber matrix, carries out surface dry curing treatment, obtains the cable finished product with solidification conductive structure layer.The application adopts the control strategy that real-time three-dimensional attitude perception and dynamic deformation compensation path planning are combined, can high precision, high adhesion directly print room temperature solidification conductive material on the surface of continuous movement cable.

Description

Technical Field

[0001] This invention relates to the field of cable manufacturing technology, and in particular to an online room temperature printing method and system for continuous cable conductive structures. Background Technology

[0002] Currently, the conductive structural layer of a cable refers to a layered structure with a specified geometric pattern and electrical function formed on the insulating or semi-conductive outer surface of the cable. Common forms include spirally wound conductive tape for shielding electromagnetic interference, serpentine electrodes for sensing, and flexible printed circuits for signal transmission. With the development of wearable devices, robot harnesses, and lightweight cables for aerospace applications, cables need to maintain the integrity and electrical stability of the conductive structure under small bending radii, which places higher demands on the manufacturing precision and adhesion reliability of the conductive structural layer.

[0003] In related technologies, Chinese invention patent CN218982067U discloses a spraying device for manufacturing wires and cables, including a base, a conductor block fixedly installed on the top of the base, wire holes opened on the surface of the conductor block, and a guide component provided at one end of the conductor block. The guide component is mainly used to uniformly transport the cable to be sprayed. By setting a stepper motor to drive the gear to rotate, the gear to drive the gear ring to rotate, and then through the cooperation of the support ring and the storage tank, the effect of uniform spraying of the cable is achieved. At this time, since the storage tank is filled with high-pressure insulating paint by a high-pressure feed pipe, and sprayed onto the surface of the cable through the nozzle, the stepper motor is controlled to rotate forward and reverse during the spraying process, thereby further deflecting the nozzle at a certain angle.

[0004] However, the aforementioned technologies that use stepper motors to drive the spray head to rotate for spraying cannot detect the positional fluctuations of the cable during its movement. This is an open-loop fixed trajectory control, which results in low coating accuracy and easy missed coating. At the same time, it is only suitable for uniform insulating paint spraying and lacks the ability to form conductive patterns, cure at room temperature, and adapt to strain, making it difficult to meet the online manufacturing requirements of high-precision conductive structures. Summary of the Invention

[0005] To address the aforementioned issues, this invention provides an online room temperature printing method and system for continuous cable conductive structures. It employs a control strategy that combines real-time three-dimensional attitude perception with dynamic deformation compensation path planning, enabling high-precision and high-adhesion direct printing of room temperature curing conductive materials onto the surface of a continuously moving cable.

[0006] The above objectives can be achieved through the following approach: A method and system for online room temperature printing of a continuous cable conductive structure includes: acquiring an outer contour measurement point cloud generated by scanning along the cable's travel direction; performing spatial registration and fitting processing on the outer contour measurement point cloud to generate a three-dimensional center path curve; decomposing the three-dimensional center path curve to obtain the cable's local pose parameters; constructing a spatial normal field on the cable surface using the local pose parameters to generate spatial pose data of the cable surface; acquiring a standard geometric model of the conductive structure to be formed; performing geometric mapping and deformation compensation on the standard geometric model using the cable surface spatial pose data to generate an online printing path trajectory; controlling an extrusion device to extrude room temperature curing conductive ink along the online printing path trajectory onto the surface of a moving cable; the room temperature curing conductive ink contains a silicone rubber matrix that can absorb moisture and undergo a cross-linking reaction at room temperature; the extrusion device's outlet is in real-time contact with the cable or maintains a following gap according to the online printing path trajectory, and the ink adheres to form a wet conductive pattern; applying forced environmental conditions to the moving cable section with the formed wet conductive pattern to accelerate the cross-linking process of the silicone rubber matrix, and performing surface drying curing treatment to obtain a finished cable with a cured conductive structure layer.

[0007] Optionally, generating the three-dimensional center path curve includes: using a high-speed contour sensor array arranged along the circumference of the cable to synchronously acquire the outer contour measurement point cloud of the cable cross section; performing a time-space coordinate transformation based on the cable travel speed on the continuously acquired outer contour measurement point cloud sequence to obtain a cable surface point cloud set; and performing fitting operations on the cable surface point cloud set to generate the three-dimensional center path curve.

[0008] Optionally, generating cable surface spatial pose data includes: taking discrete points along the three-dimensional center path curve with equal arc lengths, performing local spatial state analysis to obtain the cable's local pose parameters; using the local pose parameters of each discrete point as a reference, performing spatial normal radiation and vector smooth transition between adjacent points to form a continuous spatial normal field on the cable surface; and spatially aligning and superimposing the local pose parameters and the spatial normal field to generate cable surface spatial pose data.

[0009] Optionally, generating the online printing path trajectory includes: obtaining a standard geometric model describing the shape and size of the conductive structure to be formed; establishing a conformal mapping relationship between the vertices of the standard geometric model and the spatial surface determined by the cable surface spatial pose data; flattening the standard geometric model and fitting it onto the dynamic surface defined by the cable surface spatial pose data to generate an initial follower path; analyzing the rate of curvature change in the cable surface spatial pose data, performing strain compensation on the initial follower path, and generating the online printing path trajectory.

[0010] Optionally, the ink adherence to form a wet conductive pattern includes: acquiring the path point sequence and corresponding vector direction in the online printing path trajectory; adjusting the discharge flow rate parameter and moving speed parameter of the extrusion device in real time according to the curvature change characteristics of the path point sequence to generate an extrusion control command; using the extrusion control command to drive the extrusion device to quantitatively deliver room temperature curing conductive ink to the cable surface, the room temperature curing conductive ink maintaining its shape after extrusion due to its own thixotropic properties and wetting and spreading after contacting the cable surface, forming a wet conductive pattern of uniform thickness as the cable moves.

[0011] Optionally, the method further includes: obtaining a ready-to-use ink prepared by mixing conductive filler, room temperature vulcanizing silicone rubber and solvent; performing vacuum degassing treatment on the ready-to-use ink to eliminate internal gas and obtain a room temperature curing conductive ink that meets the requirements of the extrusion process.

[0012] Optionally, obtaining a finished cable with a cured conductive structure layer includes: setting a curing channel downstream of the printing station, establishing a controlled atmosphere environment with a target temperature and humidity level within the curing channel; guiding a cable section with a wet conductive pattern to continuously pass through the curing channel, exposing the wet conductive pattern in the controlled atmosphere environment; controlling the residence time of the wet conductive pattern in the controlled atmosphere environment, and performing integrated moisture curing and surface drying treatment to obtain a finished cable with a cured conductive structure layer.

[0013] Optionally, analyzing the rate of curvature change in the spatial pose data of the cable surface and performing strain compensation on the initial follow-up path includes: extracting the local curvature change characteristics of the spatial pose data of the cable surface; obtaining the elongation performance parameters of the room temperature curing conductive ink after curing; and, based on the local curvature change characteristics and elongation performance parameters, performing micro-scaling compensation on the line width of the conductive pattern in the initial follow-up path to generate an online printing path trajectory that restricts the pattern from breaking or becoming excessively thinned on the deformed surface.

[0014] Optionally, the method further includes: acquiring a real-time visual image of the wet conductive pattern printed onto the cable surface; extracting the edge features and centerline features of the pattern from the real-time visual image, comparing them with the online printing path trajectory to obtain a size deviation value; and inputting the size deviation value as a feedback parameter into the deformation compensation calculation for correction to obtain the corrected online printing path trajectory.

[0015] Based on the same inventive concept, this invention also provides an online room temperature printing system for continuous cable conductive structures. The system includes: a path fitting module for acquiring an outer contour measurement point cloud generated by scanning along the cable's travel direction, performing spatial registration and fitting processing on the outer contour measurement point cloud to generate a three-dimensional center path curve; a pose analysis module for decomposing the three-dimensional center path curve to obtain the cable's local pose parameters, combining the local pose parameters to construct the spatial normal field of the cable surface, and generating spatial pose data of the cable surface; and a trajectory generation module for acquiring a standard geometric model of the conductive structure to be formed, and using the cable surface spatial pose data to perform geometric processing on the standard geometric model. The system employs mapping and deformation compensation to generate an online printing path trajectory. A follow-up printing module controls the extrusion device to extrude room-temperature curing conductive ink along the online printing path trajectory onto the surface of the moving cable. The room-temperature curing conductive ink contains a silicone rubber matrix that can absorb moisture and undergo cross-linking at room temperature. The extrusion device's outlet maintains real-time contact with the cable or a following gap according to the online printing path trajectory, allowing the ink to adhere and form a wet conductive pattern. A surface-drying curing module applies forced environmental conditions to the section of the moving cable with the wet conductive pattern, accelerating the cross-linking process of the silicone rubber matrix and performing surface-drying curing to obtain a finished cable product with a cured conductive structure layer.

[0016] Compared with the prior art, the present invention has the following advantages: 1. This invention reconstructs the three-dimensional center path curve of the cable by online scanning along the cable's travel direction and analyzes the surface spatial pose data, so that the printing path of the conductive pattern can follow the bending and twisting posture of the cable in space in real time. There is no need to pre-straighten or offline position the cable, which improves the forming efficiency and positional accuracy of the conductive structure layer of the flexible cable on the continuous production line.

[0017] 2. When mapping the planar standard geometric model to the dynamic curved surface of the cable, this invention introduces a line width micro-scaling compensation mechanism based on the local curvature change characteristics of the surface and the elongation performance parameters after ink curing. By quantitatively calculating the surface strain induced by bending, the ink extrusion width is adjusted in advance, which suppresses the risk of the conductive pattern breaking or being excessively thinned when the cable is bent or stretched.

[0018] 3. This invention uses a silicone rubber-based conductive ink system that can absorb moisture and crosslink at room temperature. Combined with the design of a downstream forced moisture curing channel, the printed wet pattern is directly introduced into a controlled atmosphere with a target temperature and humidity level for surface drying curing. This eliminates the need for high-temperature baking equipment required for traditional thermal curing. The entire online printing and room temperature curing process is seamlessly integrated with the cable extrusion production line.

[0019] 4. This invention introduces real-time visual detection feedback of wet conductive patterns between the printing station and the curing channel, extracts the edge and center line features of the pattern, compares them with the online printing path trajectory, and inputs the size deviation into the deformation compensation calculation to correct the extrusion width of the subsequent path. This achieves self-correction of process disturbances such as ink flow fluctuations and substrate surface energy changes, and can maintain the consistency of conductive pattern line width for a long time.

[0020] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description, claims, and drawings. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic flowchart of an online room temperature printing method for a continuous cable conductive structure according to an embodiment of the present invention.

[0023] Figure 2 This is a centerline fitting diagram based on a surface point cloud set according to an embodiment of the present invention.

[0024] Figure 3 This is a planar unfolded view of the standard geometric model of the conductive structure to be formed according to an embodiment of the present invention.

[0025] Figure 4 This is a geometric mapping diagram of an embodiment of the present invention.

[0026] Figure 5 This is a schematic diagram of line width compensation according to an embodiment of the present invention.

[0027] Figure 6 This is a schematic diagram of extrusion parameter adjustment according to an embodiment of the present invention.

[0028] Figure 7 This is a schematic diagram of the curing residence time according to an embodiment of the present invention.

[0029] Figure 8 This is a real-time visual image according to an embodiment of the present invention.

[0030] Figure 9 This is a schematic diagram of an online room temperature printing system for a continuous cable conductive structure according to an embodiment of the present invention. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Reference Figure 1 One embodiment of the present invention proposes an online room temperature printing method for continuous cable conductive structures. It adopts a control strategy that combines real-time three-dimensional attitude perception and dynamic deformation compensation path planning, which can directly print room temperature curing conductive materials onto the surface of a continuously moving cable with high precision and high adhesion.

[0033] The method in this embodiment specifically includes: The outer contour measurement point cloud generated by scanning along the cable travel direction is acquired, and the outer contour measurement point cloud is spatially registered and fitted to generate a three-dimensional center path curve. Optionally, generating the three-dimensional center path curve includes: A high-speed profile sensor array arranged along the circumference of the cable is used to synchronously acquire the measurement point cloud of the outer profile of the cable cross-section; A time-space coordinate transformation based on the cable travel speed is performed on the continuously acquired outer contour measurement point cloud sequence to obtain a set of cable surface point clouds. A fitting operation is performed on the point cloud set on the cable surface to generate a three-dimensional center path curve.

[0034] Specifically, this process relies on a high-speed profile sensor array arranged circumferentially along the cable. This array contains multiple line laser profile sensors, each installed at equal angular intervals around the circumference of the cable's cross-section, forming a closed annular measurement area through which the cable passes. At each frame acquisition moment, each line laser profile sensor emits a fan-shaped laser line. The laser line is reflected by the cable surface and captured by the sensor's built-in camera. Using triangulation, a set of two-dimensional coordinates of the cable surface profile points within the sensor's field of view is obtained. The coordinates of all two-dimensional profile points obtained by the line laser profile sensors at the same acquisition moment are transformed into a fixed world coordinate system based on their installation angles and calibrated position parameters within the annular array, thus obtaining a complete frame of the cable cross-section's outer profile measurement point cloud. This frame of point cloud is a ring of discrete three-dimensional points, describing the circumferential shape of the cable at the moment of acquisition. As the cable continues to travel, the sensor array operates at a fixed acquisition frequency, synchronously acquiring a sequence of outer profile measurement point clouds arranged sequentially over time. To convert a time-indexed point cloud sequence into a spatially continuous set of cable surface point clouds, a time-space coordinate transformation based on the cable's travel speed is required. The cable's travel speed is measured in real-time by an encoder linked to the cable production line; the encoder's output signal records the instantaneous rate of the cable's movement along the travel direction. The time-space coordinate transformation converts the coordinates of any spatial point in a given frame of the point cloud. Mapped to points in the point cloud set on the cable surface The transformation relationship is achieved through the following formula: ; in, For distance traveled The relevant functions are as follows: , This refers to the cable twist angle per unit length, obtained through actual measurement and calibration on the production line. This is the initial twist angle, which is usually taken as 0 unless it is necessary to compensate for the known deflection of the initial segment; , These are the coordinate components of the point within the plane of the cable's cross-section; The component along the cable's travel direction in the local coordinate system of the sensor in that frame is typically 0 or a fixed offset. The point cloud of each frame in time sequence is unfolded along the cable's travel direction, forming a set of cable surface point clouds. This set of point clouds provides a complete spatial distribution description of the cable surface in the world coordinate system, with each point carrying its exact three-dimensional spatial coordinates on the cable surface. After obtaining the cable surface point cloud set, a centerline fitting operation is required to generate a three-dimensional center path curve. The first step in the centerline fitting operation is to cut the cable surface point cloud set along the currently roughly estimated cable extension direction, i.e., the z-axis direction of the world coordinate system, into a series of thin layers of a certain thickness. Each thin layer contains a small segment of the surface point cloud at the corresponding longitudinal position of the cable. For each thin layer, a planar circle or ellipse is fitted to all surface points within that layer. When the cable cross-section is approximately circular, least-squares circle fitting is used, and the calculation is expressed as finding the center coordinates and radius of the circle when the following objective function is minimized. ,have: ; in, Let j be the number of point clouds contained in the j-th thin slice layer; , These are the x and y coordinate components of the k-th point within this layer; , The coordinates of the center and radius of the circle at which the objective function is minimized; the z-coordinate of the layer center. The midpoint of the longitudinal direction of the thin slice is taken as the midpoint. Connecting all the fitted layer center points in the longitudinal order of the thin slices yields a three-dimensional polygonal line composed of discrete points. A cubic B-spline curve is used to smoothly fit this three-dimensional polygonal line, generating a three-dimensional center path curve. The control points of the B-spline curve are obtained by minimizing the fitting error. ,have: ; in, The number of control points; Let be the parameter variable of the B-spline curve, with a value range of [0,1]. Let n be the control points of the B-spline curve, denoted as . ; The basis function corresponding to the i-th control point is defined by the Cox-deBuhr recurrence relation. This curve fully describes the macroscopic trajectory of the cable in space, i.e., it is a three-dimensional center path curve. Figure 2 As shown, the semi-transparent gray dots in the figure represent the point cloud set of the cable surface obtained after spatiotemporal transformation, while the black solid line running through it is the three-dimensional center path curve.

[0035] For example, in an online printing application for a silicone rubber cable with a diameter of 20 mm and a travel speed of 100 mm / s, four line laser profile sensors with a sampling frequency of 2000 Hz were arranged along the circumference of the cable, with each frame of point cloud containing approximately 800 points. The cumulative accuracy of the travel distance was ensured by an incremental rotary encoder with a resolution of 0.01 mm. The torsion angle function was set based on a constant torsion rate of 0.05 rad / m on the production line. In the centerline fitting calculation, the thickness of the sheet layer was taken as 1 mm, corresponding to the aggregation range of 10 frames of point cloud in the travel direction. Circular fitting was performed on the 8023 points contained in a certain sheet layer to obtain the layer center coordinates as follows: The fitting radius is 10.02 mm. After fitting the center of 150 consecutive thin slices, the length of the three-dimensional center path curve obtained by B-spline smoothing is approximately 150 mm.

[0036] The local pose parameters of the cable are obtained by decomposing the three-dimensional center path curve. The spatial normal field of the cable surface is constructed by combining the local pose parameters to generate the spatial pose data of the cable surface. Optionally, generating cable surface spatial pose data includes: Points are discretely selected along the three-dimensional center path curve with equal arc lengths, and local spatial state analysis is performed to obtain the local pose parameters of the cable. Based on the local pose parameters of each discrete point, spatial normal radiation and vector smooth transition between adjacent points are performed to form a continuous spatial normal field on the cable surface. Local pose parameters are spatially aligned and superimposed with the spatial normal field to generate spatial pose data of the cable surface.

[0037] Specifically, the requirement for constant arc length discrete point selection is to select a specific number of discrete points on the curve, ensuring that the arc length between any two adjacent points remains constant. This constant value is obtained by dividing the total arc length by the number of discrete point segments. To accurately determine the position of each discrete point on the curve, a method combining numerical arc length integration and binary search is used: starting from the starting point of the curve, the arc length is gradually accumulated in small parameter steps. When the accumulated arc length reaches the target arc length value, the corresponding curve parameters are determined as the parameters of that discrete point. The spatial coordinates of the discrete point are directly obtained by substituting them into the curve equation mentioned above. The total number of discrete points is set based on the curvature change amplitude of the cable along the direction of travel and the continuity requirements of the subsequent spatial normal field. Based on statistical analysis of industrial sensor measured data, the value is set to ensure that there are no less than two discrete points per millimeter of curve arc length, thereby ensuring the accuracy of capturing the meandering and twisting shape of the cable. Local spatial state analysis is performed on each discrete point to obtain a complete set of parameters describing the local pose of the cable at that point, i.e., local pose parameters. The local pose parameters are composed of the spatial coordinates of a discrete point, the unit tangent vector, the unit principal normal vector, and the unit binormal vector of the curve at that point. For calculating the unit tangent vector at the i-th discrete point... ,have: ; in, Let be the parameter value corresponding to the i-th discrete point on the curve; Let be the first derivative vector of the curve, representing the direction of the tangent to the curve at that point; Let be the Euclidean norm of the vector. The unit principal normal vector points inwards towards the curve's curvature and is determined by the curve's second derivative and the tangent vector. For calculating the unit principal normal vector at this i-th discrete point... ,have: ; in, Let be the second derivative vector of the curve, representing the direction of the curve's acceleration at that point. The unit binormal vector is directly obtained by the cross product of the tangent vector and the principal normal vector. For calculating the unit binormal vector... ,have: ; in, The vector cross product is used. These three unit vectors are pairwise orthogonal, forming a local coordinate system attached to the discrete point, which fully describes the direction, bending direction, and torsional posture of the cable centerline at that point. After obtaining the local pose parameters of all discrete points, spatial normal radiation is performed based on the local pose parameters of each discrete point. This refers to constructing normal vectors from the centerline outwards towards the cable surface. These normal vectors describe the ideal orientation of each point on the cable surface in three-dimensional space. At the discrete point, the surface normal of the cable can be represented by a linear combination of the unit principal normal vector and the unit secondary normal vector, because these two vectors span a cross-sectional plane perpendicular to the tangent vector. For the radial direction of the line connecting the cable surface point and the discrete point on the centerline, the rotation angle of this line relative to the principal normal vector in the cross-sectional plane is represented by an angle parameter. For calculating the circumferential angle along the cable cross-section at this discrete point, the following parameters are generated. unit normal vector ,have: ; in, The circumferential angle, ranging from 0 to 2π radians, represents the rotation angle relative to the principal normal vector within the cross-sectional plane. The smooth transition between adjacent discrete points is designed to eliminate discontinuities in the normal vector caused by measurement noise or fitting bias, constructing a continuously varying normal vector field between adjacent discrete points. The smooth transition employs spherical linear interpolation, where the proportion of the curve's arc length between adjacent discrete points is... The point, the normal vector of that point ,have: ; in, For vectors and The angle between them is obtained by calculating the inverse cosine; The interpolation position scale ranges from 0 to 1. Local pose parameters are spatially aligned and superimposed with the spatial normal field. The spatial alignment operation integrates the local coordinate system information and the radiation vector of the spatial normal field at each discrete point into the same data frame. For each discrete point, the cable surface spatial pose data is organized as an indexed array, corresponding to the centerline point and the associated surface normal coverage area. Each data entry contains: the spatial coordinates of the discrete point, the tangent vector, principal normal vector, and secondary normal vector from the local pose parameters, as well as the set of normal vectors obtained by sampling the spatial normal field at that point according to the circumferential angle.

[0038] An exemplary application example is a silicone rubber cable with a diameter of 20mm and a travel speed of 100mm / s. The total arc length of the three-dimensional center path curve is 150mm, and the total number of discrete points is set to 301, corresponding to an arc length interval of 0.5mm, satisfying the density requirement of 2 discrete points per millimeter. The discrete point is located at 75mm of the arc length. ,but , , A circumferential angle sampling interval of 0.035 radians is used, corresponding to approximately 200 sampling points in the circumferential direction. 200 unit normal vectors are generated through spatial normal radiation. For the smooth transition section between 75mm and 75.5mm arc lengths, and The maximum included angle between them was measured to be 0.012 radians, and the continuity deviation of the transition normal field angle generated by spherical linear interpolation was less than 0.001 radians. The final generated cable surface spatial pose data was indexed by 301 discrete points on the centerline, with each index associated with 201 circumferential normal vectors.

[0039] Obtain the standard geometric model of the conductive structure to be formed, and use the spatial pose data of the cable surface to perform geometric mapping and deformation compensation on the standard geometric model to generate an online printing path trajectory. Optionally, generating the online printing path trajectory includes: Obtain a standard geometric model that describes the shape and size of the conductive structure to be formed; Establish a conformal mapping relationship between the vertices of the standard geometric model and the spatial surface determined by the spatial pose data of the cable surface, flatten the standard geometric model and fit it onto the dynamic surface defined by the spatial pose data of the cable surface to generate an initial follower path; Extracting local curvature variation characteristics from the spatial pose data of the cable surface; Obtain the elongation performance parameters of room temperature curing conductive ink after curing; Based on the characteristics of local curvature change and elongation performance parameters, the line width of the conductive pattern in the initial follow-up path is micro-scaled and compensated to generate an online printing path trajectory that restricts the pattern from breaking or becoming excessively thinned on the deformed surface.

[0040] Specifically, this standard geometric model defines the design of conductive patterns in a two-dimensional plane. It is typically output by computer-aided design software and includes the coordinates of a series of ordered vertices that form the pattern outline and the width attributes of the lines connecting these vertices. In the standard geometric model, the position of each vertex is represented by two-dimensional coordinates, and the design requires the width of the lines connecting the vertices. The standard geometric model can describe patterns such as simple linear grids, helical coils, or complex interdigitated electrodes, which, in a planar state, meet the electrical performance and mechanical compliance specifications of conductive structures. Figure 3 As shown, this is a predefined and unfolded standard geometric model on a two-dimensional plane. Taking a serpentine sensing electrode pattern as an example, this model precisely defines all key geometric parameters such as the shape, line width, and spacing of the pattern to be printed in vector format. Establishing a conformal mapping relationship between the vertices of the standard geometric model and the spatial surface determined by the cable surface pose data is the process of attaching the planar design pattern to the three-dimensional curved surface of the cable without angular distortion. For cases where the cable cross-section is approximately circular with a gradually changing radius, a dynamic curved surface of the cable surface is defined. ,have: ; in, It is the average radius of the cable at the arc length position u, which can be taken as a constant value when the cable cross-section is a standard circle, in millimeters; and They are curves The unit principal normal and unit secondary normal at a given point are continuously expressed by B-spline interpolation of the local pose parameters at discrete points. Establishing a conformal mapping relationship involves finding the transformation between planar coordinates and surface coordinates. Along the cable's travel direction, the abscissa of the standard geometric model directly corresponds linearly to the arc length parameter of the cable's center path, while the ordinate along the cable's circumference corresponds linearly to the product of the cable's radius and circumferential angle at that arc length position, i.e., the circumferential arc length. This allows the planar design pattern to be fitted onto the dynamic surface of the cable without angular distortion. The origin of the plane is aligned with a reference starting position on the cable surface. For the abscissa of the standard geometric model... and the vertical axis After mapping, it corresponds to the arc length position on the three-dimensional center path curve of the cable. Circumferential angle with cable surface ,have: ; in, It is the initial arc length offset, which is determined by the initial position of placing the standard geometric model longitudinally on the cable surface; The circumferential angular offset determines the initial orientation of the pattern on the cable circumference. This transformation preserves the local angles, forming a conformal mapping. Substituting the coordinates of each vertex of the standard geometric model into the surface equations through this mapping yields the corresponding point in three-dimensional space. Connecting the pattern vertices defined in the standard geometric model sequentially, while preserving the original line width properties during the connection process, results in a three-dimensional point sequence perfectly conforming to the dynamic surface—the initial follower path. For example... Figure 4 As shown, the semi-transparent curved surface represents the dynamic three-dimensional surface of the cable, while the black solid line path represents the initial follower path. Each path point of the initial follower path contains the spatial coordinates of that point and the surface normal vector at that point. The surface normal vector at point q... ,have: ; in, These are the vertex coordinates in the standard geometric model; Arc length parameter of cable center path The unit principal normal vector of the cable surface. Extract the local curvature variation features of the cable surface spatial pose data along the travel direction and circumference. These local curvature variation features include two types of principal curvatures. The principal curvature along the cable travel direction is directly determined by the geometric properties of the three-dimensional center path curve. For this cable travel direction, the principal curvature... ,have: ; The circumferential principal curvature is determined by the local cross-sectional shape of the cable surface at various arc lengths. When the cross-section is approximately circular, the circumferential principal curvature is the reciprocal of the local radius. Therefore, the circumferential principal curvature... ,have: ; For any path point on the initial follower path, calculate the tangent direction vector of the path at that point. This vector lies within the tangent plane of the surface at that point. The tangent plane is spanned by the partial derivatives of the surface with respect to the arc length and the partial derivatives with respect to the circumferential angle. The partial derivative with respect to the arc length represents the variation along the cable's travel direction, while the partial derivative with respect to the circumferential angle represents the variation along the cable's circumference. After normalizing the path tangent direction vector, it can be expressed as a linear combination of these two partial derivatives. The angle between this combination and the travel direction (i.e., the partial derivative of the surface with respect to the arc length) is denoted as the angle between the path direction and the cable's travel direction. The normal curvature along this path direction is obtained using Euler's formula. The normal curvature for this path direction... ,have: ; in, The angle between the tangential direction of the path and the direction of travel. This normal curvature describes the degree of bending of the cable surface along the printed path direction, determining the bending-induced tensile or compressive strain that the conductive pattern will withstand at that location after curing. The elongation performance parameter of the room-temperature curing conductive ink is obtained by measuring the elongation at break through a uniaxial tensile test on a sample of the cured conductive ink film; for example, a value of 0.50 represents 50%. The elongation performance parameter represents the maximum normal strain that the conductive pattern can withstand without breaking during cable bending deformation. It also references the Poisson effect and thickness reduction tolerance limits of the material, providing an upper limit constraint for width compensation. Based on the local curvature variation characteristics and the elongation performance parameter, the line width of the conductive pattern in the initial follow-up path is slightly scaled and compensated. When the cable surface has a normal curvature along the path direction at a path point, the cured pattern will be in a bending state consistent with the cable surface because the conductive pattern is tightly attached to the cable surface. Taking the cable's central axis as the neutral axis, the linear strain along the path direction at that point is... ,have: ; in, This is the distance from the surface point to the neutral axis. Positive values ​​represent tension, and negative values ​​represent compression. Tensile strain causes the width and thickness of the conductive pattern to shrink, while compressive strain may cause wrinkling or buildup. To ensure that the line width of the actual pattern after curing is as close as possible to the standard design width, a compensated printed line width is assigned to each path point on the initial follow-up path during printing. ,have: ; in, This is the standard design width. The line is pre-widened in the stretching zone and pre-narrowed in the compression zone to offset dimensional changes caused by cable bending. Simultaneously, constraints determined by elongation performance parameters are introduced: if... If the elongation performance parameter is exceeded, the print width at that point is modified, and the area where that path point is located is restricted to a high-risk fracture zone. The extrusion unit's control system can then issue a warning or reduce the travel speed to increase the self-leveling time before curing. Values ​​less than -0.3, indicating excessive compression, are also clamped to prevent ink buildup. After the above micro-scaling compensation, the initial trailing path's path point sequence, along with its respective compensated line width and normal vector, forms entirely new path data; this data is the online printing path trajectory. For example... Figure 5 As shown, on the outside of the stretched bend, the width of the printed line is increased in advance; while on the inside of the compressed bend, the width is reduced in advance.

[0041] For example, in the application of a silicone rubber cable with a diameter of 20mm and a travel speed of 100mm / s, the cable radius is taken as a constant value of 10.0mm, obtained by statistically averaging the radii of 150 thin-layer circles. The standard geometric model is based on the width... A straight-line spiral stripe pattern of mm, with a spiral angle of 45 degrees. (Take...) mm, The radian value is used to map the model vertices onto the cable surface, generating an initial follower path containing 3000 path points. The spatial pose data of the cable surface is extracted along the travel direction, specifically the curvature at an arc length of 75mm. The modulus is calculated This is equivalent to a bending radius of approximately 476 mm. Local circumferential curvature. Near this point, the angle between the path tangent and the direction of travel is... Calculate the curvature Surface strain The obtained room-temperature curing conductive ink elongation performance parameter was tested to be 0.60. At this path point... No clamping required, printed width after compensation (mm). Over the entire 150mm print length, the line width of the compensated online print path trajectory smoothly varies between 2.0mm and 3.1mm, keeping the risk of pattern breakage within the design limits.

[0042] The extrusion device controls the room temperature curing conductive ink to be extruded onto the surface of the moving cable along the online printing path. The room temperature curing conductive ink contains a silicone rubber matrix that can absorb moisture and undergo cross-linking reaction at room temperature. The discharge port of the extrusion device is in real-time contact with the cable or maintains a following gap according to the online printing path. The ink adheres and forms a wet conductive pattern. Optionally, the ink adheres to form a wet conductive pattern, including: Obtain the sequence of path points and their corresponding vector directions from the online printable path trajectory; Based on the curvature change characteristics of the path point sequence, the discharge flow rate parameters and moving speed parameters of the extrusion device are adjusted in real time to generate extrusion control commands. The extrusion device is driven by extrusion control commands to quantitatively deliver room temperature curing conductive ink to the cable surface. The room temperature curing conductive ink maintains its shape after extrusion due to its thixotropic properties and wets and spreads after contacting the cable surface, forming a uniform thickness wet conductive pattern as the cable moves.

[0043] Specifically, the path point sequence and corresponding vector directions are extracted from the online printing path trajectory. The three-dimensional coordinates of the path points directly determine the sequential positions of the extrusion device's outlet in space. The unit normal vector provides a reference for the outlet's orientation, driving the extrusion device to maintain its axis aligned with this unit normal vector during movement, ensuring that the extruded ink is always deposited on the cable surface along the surface normal. To generate extrusion control commands, the extrusion device's discharge flow rate and movement speed parameters need to be adjusted in real time based on the curvature variation characteristics of the path point sequence. The curvature variation characteristics of the path point sequence are represented by the local curvature of the online printing path itself at each path point. and its adjacent points , Constructed local curvature ,have: ; When the path point sequence is sampled densely enough, The normal curvature of the path direction calculated above can be directly taken. The curvature variation characteristics reflect the severity of the path's meandering on the cable surface. High-curvature sections experience greater bending strain, and correspondingly, wider printed line widths have been assigned in the above description. The discharge flow rate parameter represents the volume of ink extruded from the extruder nozzle per unit time. The movement speed parameter represents the combined movement speed of the extruder outlet relative to the cable surface. A constant following gap is maintained between the extruder outlet and the cable surface, determined through ink extrusion tests on a silicone rubber substrate; in this example, it is taken as 0.15 mm. The design target thickness of the wet conductive pattern is constant, determined by back-calculation based on the required sheet resistance of the conductive structure layer and the volume shrinkage rate after curing; it is taken as 0.10 mm. For calculating this discharge flow rate parameter... ,have: ; in, To design the target thickness; Here is the moving speed parameter. The cable moves along the tangent direction of the three-dimensional center path curve at a traveling speed, and the online printing path trajectory followed by the extrusion device has a time-varying angle with the cable's traveling direction. This angle is determined by the dot product of the path tangent vector at the path point and the cable's traveling tangent. To ensure that the printed pattern is free from dragging and misalignment on the cable surface, the moving speed of the extrusion device nozzle relative to the cable surface satisfies the motion composition relationship, i.e.: ; in, The speed of travel; Let be the time-varying angle. Substituting this into the volume conservation relationship, we obtain the adjustment formula for the real-time discharge flow rate parameter, namely: ; when When slight changes occur due to fluctuations in the tension of the take-up and untake-down lines, the discharge flow rate parameter is synchronously corrected according to this formula. After calculating the corresponding discharge flow rate parameter and moving speed parameter for each path point, it is compared with the path point coordinates. , legal direction The system combines extrusion valve switching signals to generate extrusion control commands that synchronize position, speed, flow rate, and attitude. These commands drive the extrusion unit to quantitatively deliver room-temperature curing conductive ink to the cable surface. The extrusion unit consists of a servo linear motion platform and a precision screw pump. The screw pump's rotational speed is converted into pulse commands based on the output flow rate parameters via a pre-calibrated speed-flow curve. When the room-temperature curing conductive ink enters the narrow flow channel inside the nozzle under the pressure of the screw pump, it experiences shear rates of thousands per second. The silicone rubber prepolymer molecular chains in the ink untangle and orient along the flow direction, causing a sharp decrease in apparent viscosity and exhibiting significant thixotropic properties. Once the ink is extruded from the nozzle, the external shear field disappears instantly, the internal physical cross-linking network is rapidly rebuilt, and the viscosity recovers to a high value within sub-seconds. This allows the extruded filament to maintain its initial cross-sectional shape, preventing flow or collapse. As the cable moves continuously, the extruded filaments are stretched and bridged to the cable surface. At the moment of contact, due to the similar surface energy between the silicone rubber matrix and the cable substrate, the ink spreads micro-spread along the surface under the wetting driving force. The spreading width is limited to the compensation design range, and finally, it adheres along the line to form a wet conductive pattern with a thickness deviation from the design target value within ±0.005 mm and neat edges. Figure 6 As shown in the figure, the solid line represents the path curvature feature, reflecting the degree of curvature of the printing path at the current position; the dotted line represents the overall movement rate; and the dashed line represents the discharge flow rate parameter. When the path becomes more curved and width compensation is required, the discharge flow rate parameter will be dynamically adjusted accordingly.

[0044] For example, in the application of a silicone rubber cable with a diameter of 20 mm and a travel speed of 100 mm / s, the online printed path trajectory contains 3000 path points, where the path point with an arc length of 75 mm forms an angle with the cable's travel tangent. The corrected printed line width at that point Millimeters. Target thickness Millimeters, the discharge flow rate parameter is obtained through the above calculation. (cubic millimeters per second), corresponding to a screw pump speed adjusted to 1200 rpm. The compensated printed line width at another path point with an arc length of 120 mm is 3.045 mm, with a tangent angle of 45 degrees, resulting in a calculated material flow rate of approximately 43.0 cubic millimeters per second. The extrusion device uses a 22G flat-mouth nozzle with an inner diameter of 0.41 mm and a constant follow-through gap of 0.15 mm. Extrusion control commands drive a three-axis motion platform to move the nozzle at a composite rate of approximately 141.4 mm per second, while simultaneously dynamically synchronizing the screw pump speed. After printing, continuous laser thickness measurements were performed at 5 points on the wet pattern on a 150 mm long cable section. The measured thickness values ​​ranged from 0.098 mm to 0.103 mm, with a total deviation from the target thickness of 0.10 mm less than 0.005 mm. The actual cured line width deviated from the design value within ±0.05 mm.

[0045] Optionally, the method further includes: Obtain a ready-to-use ink prepared by mixing conductive filler, room temperature vulcanizing silicone rubber and solvent; The ink to be used is subjected to vacuum degassing to eliminate internal gases and obtain room temperature curing conductive ink that meets the requirements of the extrusion process.

[0046] Specifically, the ink to be used here is a uniform suspension. The conductive filler is the functional component that imparts conductivity to the ink; it is typically micron- or nano-sized metal particles, such as silver or copper powder. Room temperature vulcanizing silicone rubber is the ink's matrix material; it is a liquid polymer that reacts with moisture in the air at room temperature, undergoing chemical cross-linking and transforming from a liquid to an elastic solid. The solvent is a volatile liquid that adjusts the initial viscosity of the ink to facilitate thorough and uniform mixing. These three components are mechanically mixed in a stirring device according to a predetermined mass ratio until the conductive filler is completely dispersed in the silicone rubber matrix, forming a macroscopically uniform ink to be used. During the mixing process, due to the shearing action of mechanical stirring and material transfer, air is inevitably trapped, forming tiny bubbles inside the ink. If these internal gases are not removed, they will expand at the nozzle due to sudden pressure changes during subsequent extrusion, leading to instability in the extruded flow and even splashing or line breakage. Therefore, vacuum degassing of the ink to be used is necessary. The process involves placing a container of ink to be used within a sealed vacuum chamber, then activating a vacuum pump to gradually reduce the pressure inside the chamber from atmospheric pressure to a target vacuum level. According to the ideal gas law, when the external ambient pressure decreases significantly, the volume of the tiny bubbles inside the ink expands dramatically. The final volume of the bubbles under vacuum conditions is then calculated. ,have: ; in, This represents the initial volume of the bubble under normal pressure. The ambient pressure before treatment, i.e., one standard atmosphere; This is the final absolute pressure reached within the vacuum chamber. (This is the final absolute pressure reached within the vacuum chamber.) much smaller The volume of the bubble Will be more The volume increases by tens or even hundreds of times. The increased volume of the bubbles in the ink also increases their buoyancy, accelerating their rise to the ink surface and their subsequent bursting and escape. Maintaining a vacuum for a period of time, until no more bubbles continue to emerge from the ink surface, indicates that the internal gas removal process is essentially complete. The fluid obtained after vacuum degassing is the room-temperature curing conductive ink that meets the requirements of the extrusion process.

[0047] For example, 750 grams of flake silver powder was used as a conductive filler, 240 grams of dealcoholized room temperature vulcanizing silicone rubber was used as a matrix, and 10 grams of silicone oil was used as a solvent to adjust viscosity. These three components were added to the container of a planetary mixer and stirred at 1500 rpm for 20 minutes at room temperature to obtain approximately 1000 grams of ink ready for use. Microscopic observation revealed numerous tiny air bubbles within the ink. The container containing the ink was placed in a 10-liter vacuum drying oven and sealed. The vacuum pump was started, and the absolute pressure inside the oven was reduced from atmospheric pressure (101.3 kPa) to 1.0 kPa within 10 minutes. The initial volume of the ink was... The bubble will expand to a volume of This means the bubble volume expanded more than 100 times. During the vacuuming process, the ink level was observed to rise significantly, with numerous bubbles rising as if boiling. After reaching a vacuum of 1.0 kPa, this state was maintained for 20 minutes until the bubble escape completely stopped. The vacuum pump was then turned off, and dry air was slowly injected back into the vacuum chamber to restore atmospheric pressure. At this point, the ink level in the container returned to normal, the surface was smooth, and no visible bubbles were present. This process of eliminating internal gas yielded a room-temperature curing conductive ink that met the requirements of the extrusion process, which can be directly used in subsequent printing steps.

[0048] Forced environmental conditions are applied to the mobile cable section with the wet conductive pattern to accelerate the crosslinking process of the silicone rubber matrix, and surface drying curing is performed to obtain the finished cable with a cured conductive structure layer.

[0049] Optionally, the finished cable having a cured conductive structural layer includes: A curing channel is set up downstream of the printing station, and a controlled atmosphere environment with target temperature and humidity levels is established within the curing channel. The cable section with the wet conductive pattern is guided to pass continuously through the curing channel, exposing the wet conductive pattern in a controlled atmosphere. By controlling the residence time of the wet conductive pattern in a controlled atmosphere, an integrated process of moisture curing and surface drying is performed to obtain a finished cable with a cured conductive structure layer.

[0050] Specifically, a curing channel is set downstream of the printing station. This curing channel is a closed processing chamber extending along the cable travel direction. Adjustable-height elastic sealing curtains are installed at both the inlet and outlet to reduce mass exchange with the external workshop atmosphere. After the cable is printed with a wet conductive pattern by the extrusion device, it is directly guided into the curing channel inlet via guide wheels and led out from the outlet, forming a continuous through-flow path within the chamber. The curing channel is equipped with an atmosphere control system consisting of a resistance heater, an ultrasonic atomizing humidifier, and a variable-frequency centrifugal fan. The heater has a power capacity of 1.5 kW, the humidifier has a water mist evaporation rate of 80 grams per minute, and the fan has a maximum circulating air volume of 6 cubic meters per minute. The atmosphere control system uses a set of integrated temperature and humidity sensors placed in the middle of the cavity to sample data in real time. The sensors have an accuracy of ±0.3 degrees Celsius for temperature and ±1.5% for relative humidity. The sampled signals are input to a discrete proportional-integral-derivative (DI-DE) controller, which operates at 100-millisecond cycles and outputs the heater duty cycle and humidifier power amplitude modulation signals, thereby establishing a controlled atmosphere with the target temperature and humidity levels within the curing channel. The target temperature and humidity levels are set based on the crosslinking reaction kinetics of the silicone rubber matrix in the room-temperature curing conductive ink. The silicone rubber matrix uses hydroxyl-terminated polydimethylsiloxane, and its crosslinking reaction is a moisture-initiated condensation process, with the reaction rate constant depending on temperature. With relative humidity For the reaction rate constant here ,have: ; in, The pre-exponential factor was determined by measuring the time it took for the ink to reach a crosslinking degree of 0.90 under conditions of 30 degrees Celsius and 80% relative humidity. The apparent activation energy of the crosslinking reaction is obtained based on the Arrhenius slope of three sets of variable-temperature crosslinking experiments in the temperature range of 25°C to 40°C. The molar gas constant; The humidity index was obtained by fitting five sets of crosslinking rate data at a fixed temperature of 30 degrees Celsius and relative humidity adjusted from 50% to 90%. The degree of crosslinking follows first-order kinetics over time, depending on the exposure time of the wet conductive pattern in this atmosphere. The degree of crosslinking below ,have: ; Cable sections with wet conductive patterns are guided continuously through a curing channel, moving at a constant speed determined by the production line encoder. The exposure time (residence time) of this wet conductive pattern in the controlled atmosphere is also considered. ,have: ; in, This refers to the net length of the curing channel. To ensure the conductive pattern achieves full cross-linking and touch-drying surface upon leaving the curing channel, the dwell time must meet the requirement of a cross-linking degree of not less than 0.90. Based on the kinetic equations, the theoretical time required to achieve a cross-linking degree of 0.90 is approximately 0.512 hours, or about 1840 seconds. The net length of the curing channel is designed accordingly. For example, if the cable travel speed is 100 mm / s (0.1 m / s) and the dwell time is set to 1900 seconds, the net length of the curing channel is the product of these two values, which is 190 meters. When production space is limited, a folded-back multi-path channel configuration can be used, folding the 190-meter exposure path into a multi-layered cavity with a smaller overall footprint, while still maintaining the net length and dwell time. The entire exposure process in a controlled atmosphere achieves integrated moisture curing and surface drying. Moisture curing refers to the condensation of hydroxyl-terminated polydimethylsiloxane molecular chains in the presence of moisture, forming a three-dimensional cross-linked network dominated by silicon-oxygen-silicon bonds. This locks the conductive silver powder particles within an elastic matrix, transforming the ink film from a viscous flow state to a highly elastic solid. Simultaneously, residual anhydrous xylene solvent in the ink continuously diffuses from the interior of the film to the surface and vaporizes under 30°C air circulation, achieving surface drying, resulting in the absence of adhesive tentacles on the patterned surface. To balance the solvent evaporation rate and cross-linking rate, and to prevent surface crusting from blocking internal solvent escape and causing bubbling, the circulating air velocity within the curing channel is controlled at 0.3 m / s. This value is based on thermogravimetric and infrared spectroscopy analysis of a 0.10 mm thick ink film at 80% relative humidity, confirming that the solvent mass loss half-cycle is approximately 600 seconds, while the cross-linking half-cycle is approximately 0.222 hours (800 seconds). These timescales are close and can be performed synergistically. After the wet conductive pattern has remained in the curing channel for 1900 seconds, the cross-linking degree of the ink film reaches 0.91, the solvent residue is less than 3% of the initial value, the surface pencil hardness reaches HB level, and the conductive structure layer and the cable silicone rubber matrix achieve complete mechanical integration and chemical bonding. This section of the cable, after leaving the curing channel, becomes the finished cable with a cured conductive structure layer. Figure 7 As shown, the corresponding channel length can be found on the diagram based on the established speed of the production line and the curing time required for the ink, thus providing a quantitative basis for equipment design and production line layout.

[0051] For example, in an application with a cable travel speed of 100 mm / s and a wet conductive pattern thickness of 0.10 mm, a curing channel is installed 200 mm downstream of the printing nozzle, employing a 10-layer foldback structure with an effective length of 19 meters per layer and a total net length of 190 meters. The atmosphere control system is set to a temperature of 30.0 degrees Celsius and a relative humidity of 80%, but in actual operation, the temperature and humidity fluctuate between 29.8 and 30.2 degrees Celsius and 79% and 81% relative humidity. The cable's dwell time in the curing channel is 1900 seconds. A sample of the cured conductive structure layer is taken at the channel exit, and the compressive modulus is measured to be 2.1 MPa. The DC resistance over a 10 cm length is measured to be 1.8 ohms using a digital multimeter with a four-wire method, corresponding to a sheet resistance of 0.11 ohms per square meter. Scanning electron microscopy of the ink film cross-section shows no pores, the degree of cross-linking is determined to be 0.92 using the swelling method, and the residual solvent peak area in gas chromatography decreases by 97% compared to before curing.

[0052] Optionally, the method further includes: Acquire real-time visual images of wet conductive patterns printed onto the surface of cables; The edge and centerline features of the pattern are extracted from the real-time visual image and compared with the online printing path trajectory to obtain the size deviation value; The dimensional deviation value is input as a feedback parameter into the deformation compensation calculation for correction, resulting in the corrected online printing path trajectory.

[0053] Specifically, acquiring real-time visual images of the wet conductive pattern printed onto the cable surface is achieved by setting up a vision acquisition station between the extrusion unit's outlet and the curing channel entrance. The vision acquisition station includes a global shutter complementary metal-oxide-semiconductor (CMOS) industrial camera with a pixel size of 3.45 micrometers, a resolution of 2448 x 2048 pixels, a lens focal length of 35 mm, and an object distance of 120 mm. The camera's optical axis is aligned with the local normal of the cable surface being photographed, ensuring that the acquired image is free from perspective distortion. Illumination uses a 530 nm wavelength green LED coaxial ring light source. The ring light is directed at the cable surface at a 45-degree angle and enters the camera after specular reflection, enhancing the reflectivity difference between the wet conductive ink and the silicone rubber cable substrate. The camera operates in external trigger mode, with the trigger signal generated by a pulse rising edge produced by the production line encoder every 0.5 mm of movement. This ensures a 10% overlap between adjacent frames in the cable's longitudinal direction, covering the entire section of the wet conductive pattern from printing to entering the curing channel. Each frame of the real-time visual image is a grayscale matrix, where the horizontal and vertical axes are the column and row pixel indices, respectively, and the pixel grayscale values ​​range from 0 to 255. For example... Figure 8As shown in the image, the dark, wet conductive pattern, freshly printed onto the cable surface but not yet cured, is contrasted with its bright cable substrate background. Edge and centerline features of the pattern are extracted from the real-time visual image in two stages. The first stage is pattern segmentation and edge extraction. Gaussian smoothing filtering is applied to each grayscale image frame, with a kernel size of 5x5 pixels and a standard deviation of 0.8 pixels, to suppress the subtle roughness of the ink flow edges. Then, the Otsu binarization algorithm is used to obtain an adaptive threshold, segmenting the image into a foreground ink region and a background cable region, resulting in a binary image where a value of 1 represents ink-covered pixels and 0 represents the background. The Canny edge detector is used on the binary image with a low threshold of 40 and a high threshold of 120 to extract the set of edge pixels of the pattern, which contains all pixel-level positions of the two boundaries of the pattern. The second stage is centerline feature extraction. The Zhang-Suen thinning algorithm is applied to the binary image, iteratively removing boundary pixels until a single-pixel-width pattern skeleton line is obtained. The skeleton line pixel set is then pruned, removing branches shorter than 5 pixels. Moving least-squares smoothing is then used to fit the skeleton line point set into continuous centerline features, expressed with sub-pixel precision. To obtain physical size deviation values, pixel coordinates are converted into actual spatial coordinates on the cable surface. The vision system performs intrinsic and extrinsic parameter calibration by pre-photographing a checkerboard calibration board of known dimensions, obtaining the camera's intrinsic parameter matrix and distortion coefficients. For edge points, radial and tangential distortion correction models are first applied to obtain distortion-free pixel coordinates, which are then mapped onto the cable surface using inverse perspective projection and surface constraints. The local geometry of the cable surface at the shooting point is provided by the cable surface spatial pose data, specifically the surface equation at the corresponding arc length parameter at that moment. Spatial edge points are obtained by back-projecting the image plane points through the intersection of rays and the surface. The online printing path trajectory includes the path point sequence and the corresponding compensated line width. Spatial registration is performed between the spatial edge point set and the online printed path trajectory. An iterative nearest-point algorithm is used to align the actual edge point cloud with the theoretical path point sequence, compensating for minor rigid body displacements caused by cable travel vibrations. After alignment, for each path point along the path trajectory, a cross-sectional line perpendicular to the path tangent is drawn, intersecting the actual edge point to obtain the left and right boundary intersections. The actual measured line width at this cross-section is directly calculated from the spatial distance between the two boundary intersections. The dimensional deviation value at the q-th path point is then calculated. ,have: ; in, This represents the actual measured line width at this cross-section. To obtain stable feedback parameters, median filtering is applied to the dimensional deviation values ​​of 50 consecutive path points to remove isolated outliers caused by occasional ink splatter or impurities, resulting in a smoothed dimensional deviation sequence. The dimensional deviation values ​​are then used as feedback parameters in the deformation compensation calculation for correction. The correction targets the micro-scaling compensation width calculation model upon which the online printing path trajectory is based. For the pre-calculated path ahead of the currently printing cable segment, the corrected printed line width is... ,have: ; in, The proportional feedback gain is set based on the response delay characteristics of the extrusion device to width adjustment and the system stability margin. This is a smoothed dimensional deviation feedback value obtained by median filtering the deviation between the actual measured line width and the theoretical printed line width at the d-th path point ahead of the current path point. The corrected value directly replaces the compensated printed line width value in the original path point, updates the online printing path trajectory, and then drives ink extrusion with the corrected trajectory, thereby reducing or even eliminating dimensional deviations in subsequent printing.

[0054] For example, in the application of a silicone rubber cable with a diameter of 20 mm and a travel speed of 100 mm / s, the vision acquisition station is installed 45 mm downstream of the extrusion nozzle, the camera frame trigger interval is 0.5 mm, the field of view per frame is approximately 15 mm by 12 mm, and the image resolution corresponds to a pixel equivalent of 4.5 micrometers per pixel. Near the 150 mm arc length location, originally... The actual width is measured in millimeters, but due to ink viscosity fluctuations between batches, the extruded lines widen slightly. The edge and centerline features extracted by the vision system are spatially mapped to obtain the actual width at that location. millimeters The millimeter value remains 0.074 millimeters after median filtering. The delay d is 80 path points. Take 0.72, the original value of this section millimeters, corrected to The measured line width was 2.997 mm after the cable traveled another 80 mm, a deviation of only -0.048 mm from the standard compensation expectation of 3.045 mm, a 37% reduction compared to the previous value. During a continuous printing process of 2000 mm with closed-loop correction, the line width process capability index of the wet conductive pattern improved from 1.12 to 1.48.

[0055] Based on the same inventive concept, such as Figure 9 As shown, the present invention also provides an online room temperature printing system for continuous cable conductive structures, the system comprising: The path fitting module is used to acquire the outer contour measurement point cloud generated by scanning along the cable travel direction, perform spatial registration and fitting processing on the outer contour measurement point cloud, and generate a three-dimensional center path curve. The pose analysis module is used to decompose the three-dimensional center path curve to obtain the local pose parameters of the cable, and combine the local pose parameters to construct the spatial normal field of the cable surface to generate the spatial pose data of the cable surface. The trajectory generation module is used to obtain the standard geometric model of the conductive structure to be formed, and to perform geometric mapping and deformation compensation on the standard geometric model using the spatial pose data of the cable surface to generate the online printing path trajectory. The follow-up printing module is used to control the extrusion device to extrude room temperature curing conductive ink along the online printing path onto the surface of the moving cable. The room temperature curing conductive ink contains a silicone rubber matrix that can absorb moisture and undergo cross-linking reaction at room temperature. The discharge port of the extrusion device is in real-time contact with the cable or maintains a following gap according to the online printing path. The ink adheres and forms a wet conductive pattern. The surface drying curing module is used to apply forced environmental conditions to the mobile cable section with the wet conductive pattern to accelerate the crosslinking process of the silicone rubber matrix and perform surface drying curing treatment to obtain a finished cable with a cured conductive structure layer.

[0056] It should be noted that the electrical connections between the various units described above do not necessarily represent direct or indirect connections. Any indirect connection method can be applied to the embodiments of the present invention as long as it achieves the purpose of the present invention. The above are merely exemplary embodiments of the present invention and should not be construed as limiting the scope of the present invention.

[0057] All equivalent changes and modifications made in accordance with the teachings of this invention are still within the scope of this invention. Those skilled in the art will readily conceive of other embodiments of this invention upon considering the specification and the disclosure of practical truth. This application is intended to cover any variations, uses, or adaptations of this invention that follow the general principles of this invention and include common knowledge or conventional techniques in the art not described herein.

Claims

1. A method for online room temperature printing of a continuous cable conductive structure, characterized in that, The method includes: The outer contour measurement point cloud generated by scanning along the cable travel direction is acquired, and the outer contour measurement point cloud is spatially registered and fitted to generate a three-dimensional center path curve. The local pose parameters of the cable are obtained by decomposing the three-dimensional center path curve. The spatial normal field of the cable surface is constructed by combining the local pose parameters to generate the spatial pose data of the cable surface. Obtain a standard geometric model of the conductive structure to be formed, and use the spatial pose data of the cable surface to perform geometric mapping and deformation compensation on the standard geometric model to generate an online printing path trajectory. The extrusion device controls the room temperature curing conductive ink to be extruded onto the surface of the moving cable along the online printing path. The room temperature curing conductive ink contains a silicone rubber matrix that can absorb moisture and undergo cross-linking reaction at room temperature. The outlet of the extrusion device is in real-time contact with the cable or maintains a following gap according to the online printing path. The ink adheres and forms a wet conductive pattern. Forced environmental conditions are applied to the mobile cable section with the wet conductive pattern to accelerate the crosslinking process of the silicone rubber matrix, and surface drying curing is performed to obtain a finished cable with a cured conductive structure layer.

2. The method for online room temperature printing of a continuous cable conductive structure according to claim 1, characterized in that, The generated three-dimensional center path curve includes: A high-speed profile sensor array arranged along the circumference of the cable is used to synchronously acquire the measurement point cloud of the outer profile of the cable cross-section; The continuously acquired outer contour measurement point cloud sequence is subjected to time-space coordinate transformation based on cable travel speed to obtain a set of cable surface point clouds; A fitting operation is performed on the point cloud set on the cable surface to generate a three-dimensional center path curve.

3. The method for online room temperature printing of a continuous cable conductive structure according to claim 1, characterized in that, The generated cable surface spatial pose data includes: Points are discretely selected along the three-dimensional center path curve with equal arc lengths, and local spatial state analysis is performed to obtain the local pose parameters of the cable. Based on the local pose parameters of each discrete point, a smooth transition between spatial normal radiation and vectors between adjacent points is performed to form a continuous spatial normal field on the cable surface. The local pose parameters are spatially aligned and superimposed with the spatial normal field to generate spatial pose data of the cable surface.

4. The method for online room temperature printing of a continuous cable conductive structure according to claim 1, characterized in that, The generated online printing path trajectory includes: Obtain a standard geometric model that describes the shape and size of the conductive structure to be formed; Establish a conformal mapping relationship between the vertices of the standard geometric model and the spatial surface determined by the spatial pose data of the cable surface, flatten the standard geometric model and fit it onto the dynamic surface defined by the spatial pose data of the cable surface to generate an initial follower path; The rate of curvature change in the spatial pose data of the cable surface is analyzed, strain compensation is performed on the initial follow-up path, and an online printing path trajectory is generated.

5. The method for online room temperature printing of a continuous cable conductive structure according to claim 1, characterized in that, The ink adheres and forms a wet conductive pattern, including: Obtain the path point sequence and corresponding vector direction in the online printing path trajectory; Based on the curvature change characteristics of the path point sequence, the discharge flow rate parameters and moving speed parameters of the extrusion device are adjusted in real time to generate extrusion control commands; The extrusion control command drives the extrusion device to quantitatively deliver the room temperature curing conductive ink to the cable surface. The room temperature curing conductive ink maintains its shape after extrusion due to its thixotropic properties and wets and spreads after contacting the cable surface, forming a uniform thickness wet conductive pattern as the cable moves.

6. The method for online room temperature printing of a continuous cable conductive structure according to claim 5, characterized in that, The method further includes: Obtain a ready-to-use ink prepared by mixing conductive filler, room temperature vulcanizing silicone rubber and solvent; The ink to be used is subjected to vacuum degassing to eliminate internal gas and obtain room temperature curing conductive ink that meets the requirements of the extrusion process.

7. The method for online room temperature printing of a continuous cable conductive structure according to claim 1, characterized in that, The cable product having a cured conductive structure layer includes: A curing channel is set downstream of the printing station, and a controlled atmosphere environment with a target temperature and humidity level is established in the curing channel. The cable segment with the wet conductive pattern formed thereon is guided to pass continuously through the curing channel, exposing the wet conductive pattern to the controlled atmosphere environment; By controlling the residence time of the wet conductive pattern in the controlled atmosphere, an integrated process of moisture curing and surface drying is performed to obtain a finished cable with a cured conductive structure layer.

8. The method for online room temperature printing of a continuous cable conductive structure according to claim 4, characterized in that, The analysis of the rate of curvature change in the spatial pose data of the cable surface and the strain compensation of the initial follow-up path include: Extract the local curvature variation characteristics of the cable surface spatial pose data; Obtain the elongation performance parameters of the room temperature curing conductive ink after curing; Based on the local curvature change characteristics and the elongation performance parameters, the line width of the conductive pattern in the initial follow-up path is micro-scaled and compensated to generate an online printing path trajectory that restricts the pattern from breaking or becoming excessively thinned on the deformed surface.

9. The method for online room temperature printing of a continuous cable conductive structure according to claim 1, characterized in that, The method further includes: Acquire a real-time visual image of the wet conductive pattern printed onto the cable surface; The edge features and centerline features of the pattern are extracted from the real-time visual image and compared with the online printing path trajectory to obtain the size deviation value; The dimensional deviation value is input as a feedback parameter into the deformation compensation calculation for correction, resulting in the corrected online printing path trajectory.

10. An online room temperature printing system for a continuous cable conductive structure, applied to the online room temperature printing method for a continuous cable conductive structure as described in any one of claims 1-9, characterized in that, The system includes: The path fitting module is used to acquire the outer contour measurement point cloud generated by scanning along the cable travel direction, perform spatial registration and fitting processing on the outer contour measurement point cloud, and generate a three-dimensional center path curve. The pose analysis module is used to decompose the three-dimensional center path curve to obtain the local pose parameters of the cable, and combine the local pose parameters to construct the spatial normal field of the cable surface to generate the spatial pose data of the cable surface. The trajectory generation module is used to obtain the standard geometric model of the conductive structure to be formed, and to perform geometric mapping and deformation compensation on the standard geometric model using the spatial pose data of the cable surface to generate an online printing path trajectory. The follow-up printing module is used to control the extrusion device to extrude room temperature curing conductive ink along the online printing path onto the surface of the moving cable. The room temperature curing conductive ink contains a silicone rubber matrix that can absorb moisture and undergo cross-linking reaction at room temperature. The discharge port of the extrusion device is in real-time contact with the cable or maintains a following gap according to the online printing path, and the ink adheres to form a wet conductive pattern. The surface drying curing module is used to apply forced environmental conditions to the mobile cable section with the wet conductive pattern formed thereon, accelerate the crosslinking process of the silicone rubber matrix, perform surface drying curing treatment, and obtain a finished cable with a cured conductive structure layer.

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