A wire harness concentricity and wire harness end perimeter visual inspection system

Abstract

This invention discloses a visual inspection system for wire harness concentricity and circumferential inspection of wire harness ends, comprising an isolation wall, a wire harness clamp, a prism assembly, and a vision camera; the wire harness clamp and the prism assembly are located on the outer and inner sides of the isolation wall, respectively, and the vision camera is located on the side of the prism assembly away from the isolation wall; the isolation wall has a wire harness end insertion port, and the wire harness end insertion port is coaxial with the axis of the vision camera; when the wire harness end is inserted coaxially from the wire harness end insertion port and reaches the inner side of the isolation wall, the wire harness clamp outside the wire harness end insertion port can clamp the part of the wire harness near the wire harness end; the prism assembly includes at least six total reflection prism units arranged in a circular array around the axis of the wire harness end insertion port, realizing automated and efficient inspection of the circumferential quality and concentricity of the wire harness end.

Description

Technical Field

[0001] This invention belongs to the field of wire harness visual inspection. Background Technology

[0002] Wire harnesses are fundamental components in modern industry, particularly in the automotive, aerospace, and home appliance sectors. The processing quality of wire harness ends, especially their concentricity—the coaxiality of the internal conductors with the external insulation layer or terminals—and the integrity of the circumferential surface, such as the presence of "flying wires," damaged insulation, or poor crimping, directly affects the reliability of the connection, conductivity, and long-term safety. Therefore, high-precision, automated visual inspection of wire harness ends is a crucial step in the production process.

[0003] Limitations of multi-camera inspection solutions: To achieve comprehensive 360° circumferential surface inspection of the wire harness end, a common approach is to use multiple industrial cameras arranged around the wire harness from different angles. Each camera is responsible for capturing a side image from a specific angle. This approach suffers from high system costs, requires multiple sets of cameras, lenses, and light sources, has a complex system structure, occupies a large space, and necessitates strict synchronization and calibration of the images acquired by multiple cameras, making maintenance and debugging difficult.

[0004] Interference issues with single-camera setups combined with prism arrays: Another approach is to use a single camera in conjunction with a set of reflective prisms arranged in a ring around the beam, attempting to capture reflected images from multiple sides simultaneously. However, this approach suffers from an inherent and insurmountable flaw: optical path interference. Due to mutual reflections between the prisms, light rays from different sides of the beam will cross-reflect between the prisms, resulting in severe ghosting, artifacts, and mutual interference in the final image acquired by the camera. This causes image clutter, a sharp drop in signal-to-noise ratio, and makes it difficult for subsequent image processing algorithms to accurately extract features, severely impacting the accuracy and reliability of detection.

[0005] The challenge of precise positioning of flexible wire harnesses: Cables themselves are not rigid and possess a degree of flexibility. Even when clamped at the base, the free end may still slightly bend or deviate due to its own stress, gravity, or minor deformations from previous processing. This prevents the actual axis of the wire harness end from perfectly aligning with the theoretical optical axis of the vision system. When performing end-face concentricity detection, this minute offset is directly interpreted by the vision system as a concentricity error, leading to misjudgment.

[0006] Therefore, existing visual inspection solutions either lack advantages in cost and complexity or have inherent defects in imaging quality, and generally fail to effectively solve the problem of precise positioning of flexible wire harnesses. There is an urgent need for a control system that can balance high imaging quality, high detection accuracy, and reasonable cost to achieve automated and efficient inspection of the circumferential quality and concentricity of the wire harness ends. Summary of the Invention

[0007] Purpose of the invention: In order to overcome the shortcomings of the existing technology, the present invention provides a visual inspection system for wire harness concentricity and wire harness end circumferential direction, so as to realize the automated and efficient inspection of the circumferential quality and concentricity of wire harness ends.

[0008] Technical solution: To achieve the above objectives, the present invention provides a wire harness concentricity and wire harness end circumferential visual inspection system, comprising an isolation wall, a wire harness clamp, a prism assembly, and a vision camera; the wire harness clamp and the prism assembly are located on the outer and inner sides of the isolation wall, respectively, and the vision camera is located on the side of the prism assembly away from the isolation wall; The isolation wall has a wire harness insertion port that is coaxial with the axis of the vision camera. When the wire harness end is inserted coaxially from the wire harness insertion port and reaches the inside of the isolation wall, the wire harness clamp outside the wire harness insertion port can clamp the part of the wire harness near the wire harness end. The prism assembly includes at least six total reflection prism units arranged in a circular array around the axis of the wire harness insertion port. When the wire harness end is inserted from the wire harness insertion port and reaches the inside of the isolation wall, each total reflection prism unit is evenly distributed around the wire harness end. The side of each total reflection prism unit near the wire harness end is the prism total reflection surface.

[0009] Furthermore, taking any total internal reflection prism unit as an example, the side image of the wire harness end near the total internal reflection prism unit enters the field of view of the vision camera after being reflected by the total internal reflection surface of the prism unit; at the same time, the vision camera can also directly capture the end image of the wire harness end along the axial direction.

[0010] Furthermore, within the enclosure of the six total internal reflection prism units, there is a conical optical ring wall coaxial with the wire harness insertion port. The thicker end of the conical optical ring wall faces the vision camera, and the conical optical ring wall is made of a non-transparent material.

[0011] Furthermore, a portion of the conical optical ring wall near the narrow end of its cone has a light-transmitting window cut out along the generatrix of the cone.

[0012] Furthermore, a coaxial reference ring is integrally mounted on the narrow end of the conical optical ring wall, and a rotating ring is integrally mounted on the thick end of the conical optical ring wall. The outer ring of the rotating ring is rotatably mounted on the floating ring via bearings. During the rotation of the conical optical ring wall around its own axis, the light-transmitting window successively corresponds to the total internal reflection surface of each total internal reflection prism unit. The total internal reflection surfaces of prisms that do not correspond to the light-transmitting window are optically isolated from the end of the wire bundle by the conical optical ring wall. The image on the side of the end of the wire bundle is projected onto the corresponding total internal reflection surface through the light-transmitting window and enters the field of view of the vision camera after being reflected by the total internal reflection surface of the prism. The floating ring and the conical optical ring wall can move closer to or away from the isolation wall as a whole. The prism assembly includes three sets of wire harness end constraint units arranged in a circular array around the axis of the conical optical ring wall. Each set of constraint units is located in the gap between two adjacent total reflection prism units. Each set of wire harness end constraint units includes a roller arm, a constraint roller, a guide rod, a ball guide sleeve, a thrust spring, a universal ball rod, and a floating seat extending radially along the coaxial reference ring. The floating seat slides against the inner wall of the isolation wall. A roller arm is fixedly connected along the length of the end of the floating seat near the axis of the coaxial reference ring. A constraint roller is rotatably installed at the end of the roller arm. A guide rod is fixedly connected along the length of the end of the floating seat away from the axis of the coaxial reference ring. The guide rod is coaxially guided and fitted onto the ball guide sleeve. The ball guide sleeve is fixed to the isolation wall. A thrust spring is installed between the ball guide sleeves, and the thrust spring generates a thrust on the floating seat. A universal ball rod is fixedly connected to the floating seat. A universal ball is rotatably installed at the end of the universal ball rod. The axis of the universal ball rod is perpendicular to the generatrix at the intersection of the outer conical surface of the conical optical ring wall.

[0013] Furthermore, in the initial state, each thrust spring stores elastic potential energy, and the universal ball rolls tangentially with the outer conical surface of the thick end of the conical optical ring wall. During the rotation of the conical optical ring wall along the axis, the universal ball always rolls in cooperation with the outer conical surface of the conical optical ring wall. In the initial state, the three constraint rollers of the three sets of wire harness end constraint units are distributed in a circumferential array and are in a state of mutual distance. The area enclosed by the three constraint rollers can freely pass through the wire harness end.

[0014] Furthermore, each prism's total reflection surface forms a ° angle with the visual camera's axis; Furthermore, the wire harness end is inserted coaxially from the wire harness end insertion port and reaches the inside of the isolation wall. The wire harness clamp clamps the part of the wire harness near the wire harness end, thereby performing initial positioning and shaping of the wire harness. The conical optical ring rotates around its own axis, and the vision camera successively acquires images from six directions on the side of the wire harness end, performing optical detection on the six directions on the side of the wire harness end. The gear-driven motor drives the conical optical ring wall to rotate adaptively around its own axis through meshing transmission, so that the light window rotates to avoid the three sets of wire harness end constraint units; The floating ring and the conical optical ring wall move away from the isolation wall as a whole; then the vision camera captures images of the end of the wire harness and the coaxial reference ring along the axial direction. The vision system first compares the circumferential profile of the end of the wire harness with the coaxiality of the coaxial reference ring, and then compares the coaxiality between the wire core of the end of the wire harness and the circumferential profile of the end of the wire harness.

[0015] Beneficial effects: This invention achieves significant technical benefits through innovative mechatronics-optical integration design, specifically in the following aspects: This system achieves high-efficiency and high-precision comprehensive visual inspection: using only a single vision camera, combined with a rotating beam-splitting conical optical ring structure and a circumferentially arranged total internal reflection prism group, it can acquire high-definition images of the 360° circumferential side surface and end face of the wire harness end in a time-division manner. It overcomes the problem of mutual interference between multiple optical signals, avoids ghosting and imaging chaos, and achieves high-efficiency, blind-spot-free visual inspection of wire harness end "flying wires," surface damage, and crimping quality.

[0016] The technical challenge of precise positioning of flexible wire harnesses has been solved: the axial displacement of the conical optical ring wall is converted into the synchronous radial convergence motion of three constraint rollers, which automatically performs three-point centering mechanical correction on the end of the wire harness.

[0017] This solution achieves functional synergy between optical isolation, mechanical alignment, and reference positioning: The core innovation lies in the integrated multi-functional conical optical ring wall. Its rotation enables time-division optical isolation, while its axial displacement simultaneously drives the mechanical alignment mechanism, precisely positioning the coaxial reference ring. This highly integrated design, with its "one-action-multiple-functions" approach, ensures close coordination between the three actions of optical shielding, harness alignment, and reference positioning, guaranteeing system efficiency and timing accuracy, and significantly improving the system's compactness, reliability, and automation.

[0018] Mechanical alignment ensures that the harness axis coincides with the camera optical axis, and the moving coaxial reference ring precisely surrounds the harness end, establishing a known high-precision mechanical benchmark for measurement. The vision system first determines the coaxiality between the harness outer perimeter and the reference ring, and then evaluates the coaxiality between the internal wire core and the outer perimeter, forming a progressive and reliable judgment logic. This enables highly accurate and quantifiable detection of the concentricity of the harness end.

[0019] This solution integrates complex optical inspection with precise mechanical positioning, ultimately forming a compact, cost-controllable, comprehensive, and highly accurate automated solution that effectively meets the industrial needs of wire harness production for rapid and accurate inspection of end quality and concentricity. Attached Figure Description

[0020] Figure 1 This is an overall side view of the structure of this scheme in two states; Figure 2 This is a schematic diagram of the "Step One" process; Figure 3 This is an overall breakdown diagram of the solution; Figure 4 for Figure 3 Axial view of the leftmost component; Figure 5 for Figure 1 A three-dimensional image; Figure 6 for Figure 5 The above is a disassembly diagram; Figure 7 for Figure 5 The following is a disassembly diagram. Detailed Implementation

[0021] The invention will now be further described with reference to the accompanying drawings.

[0022] As attached Figures 1 to 7 The system shown is a visual inspection system for wire harness concentricity and circumferential inspection of wire harness ends, such as Figure 1 The system includes a vertical isolation wall 3, a wire harness clamp 2, a prism assembly 4, and a vision camera 5. The wire harness clamp 2 and the prism assembly 4 are located on the outer and inner sides of the isolation wall 3, respectively, and the vision camera 5 is located on the side of the prism assembly 4 away from the isolation wall 3. The isolation wall 3 is used to physically and optically separate the external environment from the internal imaging area, preventing external stray light from interfering with the vision camera's imaging. The wire harness clamp 2 is pneumatically or servo-driven, with adjustable clamping force and self-centering function, which can automatically correct the wire harness position during clamping and improve the initial positioning accuracy. The vision camera 5 is preferably a high-resolution industrial CCD or CM camera, equipped with a telecentric lens to ensure that no perspective distortion occurs during image acquisition, which is beneficial for subsequent image processing and dimensional measurement.

[0023] like Figure 2 The isolation wall 3 has a wire harness end insertion port 8 cut out, and the wire harness end insertion port 8 is coaxial with the axis of the vision camera 5. Under the drive of the robot arm, the wire harness end 1a of the wire harness 1 is inserted coaxially from the wire harness end insertion port 8. When it reaches the inside of the isolation wall 3, the wire harness clamp 2 outside the wire harness end insertion port 8 can clamp the part of the wire harness 1 near the wire harness end 1a, thereby performing initial positioning and shaping of the wire harness 1.

[0024] The diameter of the wire harness insertion port 8 is larger than the maximum allowable outer diameter of the wire harness, ensuring that the wire harness can be inserted without interference and reducing the entry of external light; the robot arm adopts a six-axis precision model and is equipped with a flexible gripper at the end, which can adapt to the gripping and insertion operation of different wire diameters, ensuring that the end insertion process is smooth and coaxial.

[0025] like Figure 3 As shown, the prism assembly 4 includes at least six total internal reflection prism units 10 arranged in a circular array around the axis of the wire harness insertion port 8. When the wire harness end 1a is inserted from the wire harness insertion port 8 and reaches the inner side of the isolation wall 3, the six total internal reflection prism units 10 are evenly distributed around the wire harness end 1a. The side of each total internal reflection prism unit 10 closest to the wire harness end 1a is the prism total internal reflection surface 10a, and each prism total internal reflection surface 10a forms a 45° angle with the axis of the vision camera 5.

[0026] The prism unit 10 uses a high-precision right-angle prism with an enhanced reflection film on the total reflection surface to ensure uniform brightness and low distortion of the reflected image under different lighting conditions. The circular arrangement of the six prisms can fully cover the 360° range of the wire harness side, with no blind spots, providing a hardware foundation for subsequent time-division imaging.

[0027] Taking any total internal reflection prism unit 10 as an example, the side image of the wire harness end 1a near the total internal reflection prism unit 10 is reflected by the total internal reflection surface 10a of the prism of the total internal reflection prism unit 10 and enters the field of view of the vision camera 5; at the same time, the vision camera 5 can also directly capture the end image of the wire harness end 1a along the axial direction; in this way, by using a vision camera 5, it is possible to simultaneously capture the end of the wire harness and the side of the wire harness end in six directions, thereby judging the quality of the side of the wire harness end and whether there is "flying wire" and coaxiality.

[0028] The system achieves multi-angle imaging with a single camera, significantly reducing hardware costs and system complexity. The vision system integrates image fusion algorithms, which can simultaneously analyze the end face and multiple side views to comprehensively judge defects such as wire harness end face flatness, insulation layer integrity, conductor exposure, and "flying wires".

[0029] If the vision camera simultaneously receives images reflected from six total internal reflection prism units 10, the six total internal reflection prism units 10 will not only reflect the side image of the wire harness end, but also cause mutual reflection between the six total internal reflection prism units 10, resulting in mutual interference between their images, causing a large number of ghostings, interference, and indistinguishable images, thus leading to chaotic acquired images. At the same time, since the wire harness 1 being detected is not a completely rigid structure, although the part of the wire harness 1 near the wire harness end 1a is clamped and positioned by the wire harness clamp 2, the wire harness end 1a may still be slightly deflected due to its own twisting and the influence of gravity, causing the axis of the wire harness end 1a to not be well aligned with the axis of the vision camera 5. Consequently, the vision recognition system of the vision camera 5 cannot accurately determine the coaxiality between the wire core and the circumferential contour of the wire harness end 1a through the end face image of the wire harness end 1a. To address this, the following structure was designed: Within the enclosure of the six total internal reflection prism units 10, a conical optical ring wall 13 is provided, coaxial with the wire harness insertion port 8. The thicker end of the conical optical ring wall 13 faces the vision camera 5. The conical optical ring wall 13 is made of non-transparent material, and the inner conical surface is coated with black. The conical optical ring wall 13 is made of metal or high-strength engineering plastic, and the inner conical surface is treated with black matte finish, which greatly reduces internal stray light reflection. Its conical structure helps to guide the optical path in a limited space and serves as a mechanical reference for subsequent coaxial correction.

[0030] A coaxial reference ring 14 is integrally mounted on the narrow end of the conical optical ring wall 13, and a rotating ring 50 is integrally mounted on the thick end of the conical optical ring wall 13. The outer ring of the rotating ring 50 is rotatably mounted on a floating ring 16 via a bearing 15. The inner ring of the rotating ring 50 is provided with transmission teeth arranged along its contour. A gear drive motor is mounted on the floating ring 16. The gear at the output end of the gear drive motor meshes with the transmission teeth of the inner ring of the rotating ring 50, thereby driving the rotating ring 50 and the conical optical ring wall 13 to rotate actively along their own axes. The gear drive motor is preferably a stepper motor or a servo motor, equipped with a reducer to improve the rotation control accuracy. The system achieves precise angle control of the conical optical ring wall 13 through encoder feedback, ensuring that the light transmission window 12 can be accurately stopped in front of any prism unit.

[0031] A portion of the conical optical ring wall 13 near the narrow end of its cone has a light-transmitting window 12 cut out along the generatrix of the cone. As the conical optical ring wall 13 rotates around its own axis, the light-transmitting window 12 successively corresponds to the total internal reflection surface 10a of each total internal reflection prism unit 10. The total internal reflection surface 10a of the prism that does not correspond to the light-transmitting window 12 is optically isolated from the end of the wire bundle 1a by the conical optical ring wall 13. The image on the side of the end of the wire bundle 1a is projected onto the corresponding total internal reflection surface 10a through the light-transmitting window 12, and enters the field of view of the vision camera 5 after being reflected by the total internal reflection surface 10a.

[0032] The width of the light-transmitting window 12 has been optimized through optical simulation to ensure that the field of view covers the corresponding side beam surface while avoiding the simultaneous exposure of adjacent prism units. This time-division imaging mechanism fundamentally eliminates the mutual interference of multiple reflected light rays, ensuring clear images without ghosting.

[0033] The floating ring 16 is connected to the isolation wall 3 through several telescopic devices 7 parallel to the axis of the conical optical ring wall 13. Driven by the telescopic devices 7, the floating ring 16 and the conical optical ring wall 13 move closer to or further away from the isolation wall 3 as a whole.

[0034] The telescoping device 7 can be implemented by an electric push rod, a cylinder or a linear motor, and has high rigidity and repeatability, ensuring that the conical optical ring wall 13 maintains coaxiality with the camera axis during axial movement, without affecting the imaging optical path.

[0035] like Figure 4 The location of the prism assembly 4 also includes three sets of wire bundle end constraint units 9 arranged in a circular array around the axis of the conical optical ring wall 13, with each set of constraint units 9 located in the gap between two adjacent total reflection prism units 10.

[0036] like Figure 6Each single-unit wire harness end constraint unit 9 includes a roller arm 17, a constraint roller 11, a guide rod 20, a ball guide sleeve 19, a thrust spring 21, a universal ball rod 22, and a floating seat 18 extending radially along the coaxial reference ring 14. The floating seat 18 slides against the inner wall of the isolation wall 3. A roller arm 17 is fixedly connected along the length of the end of the floating seat 18 closest to the axis of the coaxial reference ring 14. A constraint roller 11 is rotatably mounted at the end of the roller arm 17. The floating seat 18 is further away from the axis of the coaxial reference ring 14. A guide rod 20 is fixedly connected along the length direction at one end. The guide rod 20 is coaxially guided and fitted on the ball guide sleeve 19. The ball guide sleeve 19 is fixed on the isolation wall 3. A thrust spring 21 is provided between the ball guide sleeve 19 and the ball guide sleeve 19. The thrust spring 21 generates a thrust on the floating seat 18. A universal ball rod 22 is fixedly connected to the floating seat 18. A universal ball 23 is rotatably provided at the end of the universal ball rod 22. The axis of the universal ball rod 22 is perpendicular to the generatrix at the intersection of the outer conical surface of the conical optical ring wall 13.

[0037] The surface of the constraint roller 11 is covered with a flexible material such as polyurethane or rubber, which provides sufficient friction and avoids scratching the surface of the wire harness; the preload of the thrust spring 21 is calculated and tested to provide sufficient radial constraint force while avoiding excessive compression that could cause wire harness deformation; the universal ball bearing 23 ensures rolling contact with the outer conical surface of the conical optical ring wall 13, resulting in low friction and smooth movement.

[0038] In the initial state, each thrust spring 21 stores elastic potential energy, and the universal ball 23 rolls tangentially with the outer conical surface of the thick end of the conical optical ring wall 13. During the rotation of the conical optical ring wall 13 along the axis, the universal ball 23 always rolls with the outer conical surface of the conical optical ring wall 13. In the initial state, the three constraint rollers 11 of the three sets of wire harness end constraint units 9 are arranged in a circumferential array and are in a state of mutual distance. The area enclosed by the three constraint rollers 11 can freely pass through the wire harness end 1a.

[0039] Working principle: Step 1, as follows Figure 2 As shown, based on the initial state, driven by the robot arm, the wire harness end 1a of the wire harness 1 is inserted coaxially from the wire harness end insertion port 8 and reaches the inner side of the isolation wall 3. The wire harness clamp 2 clamps the part of the wire harness 1 near the wire harness end 1a, thereby performing initial positioning and shaping of the wire harness 1. At this time, the wire harness 1 reaches the enclosure range of the conical optical ring wall 13. After clamping, the system confirms that the clamping is in place through the sensor on the wire harness clamp, and then sends a signal to proceed to the next operation, ensuring the reliability and automation of the process.

[0040] Step two, as Figure 5 The image above and Figure 6The gear-driven motor drives the conical optical ring wall 13 to slowly rotate around its own axis through meshing transmission. During the rotation of the conical optical ring wall 13 around its own axis, the light-transmitting window 12 corresponds to the total reflection surface 10a of each total reflection prism unit 10 in turn. The total reflection surface 10a of the prism that does not correspond to the light-transmitting window 12 is optically isolated from the end of the wire harness 1a by the conical optical ring wall 13, thereby avoiding mutual interference between the images of the six total reflection prism units 10. The image of the side of the end of the wire harness 1a is projected onto the corresponding total reflection surface 10a through the light-transmitting window 12, and enters the field of view of the vision camera 5 after being reflected by the total reflection surface 10a. When the conical optical ring wall 13 slowly rotates around its own axis for a complete revolution, the vision camera 5 acquires images from the six directions of the side of the end of the wire harness 1a in turn, thereby realizing optical detection of the six directions of the side of the end of the wire harness 1a. The vision camera triggers a shot after rotating by one angle interval (e.g., 60°) to acquire a set of high-resolution side views; the system software automatically stitches and processes these six images to reconstruct the complete three-dimensional information of the wire harness's side surface and accurately detect defects such as surface damage, poor crimping, and loose wires.

[0041] Step 3: The gear-driven motor drives the conical optical ring wall 13 to rotate adaptively around its own axis through meshing transmission, so that the light-transmitting window 12 rotates to avoid the three sets of wire harness end constraint units 9, thus preventing the universal ball bearings 23 of the wire harness end constraint units 9 from rolling to the light-transmitting window 12 in the next step; this step is controlled by a preset angle program, so that the light-transmitting window 12 stops precisely at a safe angle without mechanical interference, ensuring the smooth progress of subsequent axial movement.

[0042] Step four, as Figure 5 In the diagram below, the telescopic devices 7 are synchronously controlled to extend, causing the floating ring 16 and the conical optical ring wall 13 to move away from the isolation wall 3 as a whole. At this time, under the thrust of the thrust spring 21 and the constraint of the outer conical surface of the conical optical ring wall 13, the universal balls 23 of the three sets of wire harness end constraint units 9 roll along the generatrix direction of the conical optical ring wall 13 towards the thin end of the outer conical surface of the conical optical ring wall 13. This causes the three constraint rollers 11 of the three sets of wire harness end constraint units 9 to move closer to each other. Finally, the three constraint rollers 11 move inward to the outer circumferential surface tangent to the root of the wire harness end 1a. At this time, under the joint constraint of the three constraint rollers 11 arranged in a circumferential array, the axis of the wire harness end 1a is maximized to be coaxial with the axis of the vision camera 5. At the same time, the coaxial reference ring 14 connected to the thin end of the conical optical ring wall 13 is just displaced along the axial direction to the coaxial center surrounding the wire harness end 1a. Figure 7 As shown.

[0043] The inner diameter of the coaxial reference ring 14 matches the nominal outer diameter of the wire harness, and its inner ring surface serves as a precision reference for coaxiality measurement. The three-roller constraint mechanism forms a three-point centering structure, which can automatically compensate for slight misalignment, bending or ellipticity errors in the wire harness and achieve high-precision mechanical alignment.

[0044] Step 5: The vision camera 5 captures images of the end of the wire harness 1a and the coaxial reference ring 14 along the axial direction. The vision system first compares the circumferential contour of the wire harness end 1a with the coaxiality of the coaxial reference ring 14. If the coaxiality of the circumferential contour of the wire harness end 1a with the coaxial reference ring 14 reaches the preset value, it indicates that the axis of the wire harness end 1a coincides with the axis of the vision camera 5, and further judgment can be made. On this basis, the vision system then measures the coaxiality between the wire core of the wire harness end 1a and the circumferential contour of the wire harness end, and finally judges whether the coaxiality between the wire core of the wire harness end 1a and the circumferential contour of the wire harness end meets the requirements.

[0045] The vision system employs a sub-pixel edge extraction algorithm and a circle center fitting technique to accurately calculate the concentricity error between the outer contour of the wire harness and the coaxial reference ring. If the concentricity is acceptable, the system further analyzes the relative position of the wire core (conductor) region and the outer contour, calculates the wire core eccentricity, and determines whether it is within the allowable tolerance range. The system ultimately generates an inspection report, which includes the concentricity value, defect image, and pass / fail determination.

[0046] The core principle of this solution is to use a highly integrated electromechanical-optical system. By combining time-division imaging with active mechanical correction, a single vision camera can efficiently and accurately complete two major functions: 360° side appearance inspection of the wire harness end and end face concentricity measurement. This effectively solves two major technical problems: multi-path optical interference and positioning deviation caused by wire harness flexibility.

[0047] Key innovation: The multi-functional integration and collaborative working mechanism of the conical optical ring wall 13 integrates the core actuators of four key functions: optical isolation, mechanical transmission, centering constraint and reference provision; greatly improving the system's compactness, efficiency and accuracy.

[0048] 1. Core Function 1: Optical Time-Division Switching and Isolation. Principle: The body of the conical optical ring wall 13 is made of non-transparent material, and the black coating on its inner conical surface can absorb stray light to the maximum extent. The only open light-transmitting window 12 on the ring wall is the only lower channel that allows side light from the beam to pass through. The ring wall is rotated around its axis by a gear-driven motor, so that the light-transmitting window 12 is aligned sequentially and individually with each total internal reflection prism unit 10 distributed in the circumferential array. This physically isolates the imaging light path of the other five prism units that are not currently aligned with the light-transmitting window 12, eliminating multiple reflections, ghosting, and optical path interference caused by simultaneous imaging by multiple prisms, and ensuring that the vision camera only captures a clean, interference-free side view each time.

[0049] 2. Core Function Two: Drive Centering Constraint Mechanism. Principle: The outer conical surface of the conical optical ring wall 13 is designed as a precise mechanical inclined plane (cam structure). The universal balls 23 of the three sets of wire harness end constraint units 9 are always pressed against this outer conical surface under the action of the thrust spring 21. When the telescoping device 7 drives the entire floating ring 16 and the conical optical ring wall 13 to make axial displacement away from the isolation wall 3 along the axis, since the generatrix of the outer conical surface is continuously changing, the universal balls 23 pressed against it will be forced to move along the generatrix of the conical surface (i.e., radially) towards the narrow end of the cone (i.e., the direction of the center). This radial movement is ultimately converted into the synchronous radial convergence movement of the three constraint rollers 11 through the universal ball rod 22, the floating seat 18, and the roller arm 17. This avoids the problem that the free end of the wire harness (end 1a) will still be slightly deflected due to gravity or residual stress, causing its axis to not coincide with the optical axis of the vision camera, making the directly captured end face image unusable for accurate coaxiality measurement. This design creatively transforms the axial linear motion of the optical ring wall into a synchronized retracting motion of a three-jaw radial constraint mechanism through its unique outer conical profile. These three constraint rollers 11 simultaneously contact and straighten the wire harness end from three directions, forming a "three-point centering" structure. This actively and mechanically corrects the potentially misaligned wire harness end 1a to a position coaxial with the axis of the vision camera 5, providing a crucial mechanical reference for subsequent high-precision concentricity measurements.

[0050] 3. Core Function Three: Precise Positioning of the Coaxial Reference Ring. Principle: The coaxial reference ring 14 and the conical end of the conical optical ring wall 13 are integrally formed coaxially. When the conical optical ring wall 13 performs the aforementioned axial displacement function, the coaxial reference ring 14 moves synchronously along with it. At the end of its stroke, the coaxial reference ring 14 moves precisely to a pre-calculated position, coaxially surrounding the corrected wire harness end 1a. A known high-precision mechanical reference (the inner hole of the coaxial reference ring 14) is used to evaluate the concentricity of the wire harness's outer contour. The positioning of the coaxial reference ring 14 is entirely determined by the axial displacement of the conical optical ring wall 13, requiring no additional drive mechanism. This integrated follow-up design ensures a high degree of consistency and repeatability in the final position of the reference ring and the wire harness alignment correction action. The corrected wire harness axis coincides with the camera axis, and the axis of the coaxial reference ring 14, which arrives at this time, also coincides with the camera axis, thus making its inner hole a perfect absolute reference for visually judging the concentricity of the wire harness's outer perimeter.

[0051] The conical optical ring wall 13 drives the two major functional modules of optical imaging and mechanical correction in series through two motion modes: rotation and axial displacement. This highly integrated design of "one motion for multiple functions" is the core highlight of this solution, which is different from the independent working mode of traditional subsystems. It significantly simplifies the system structure, reduces manufacturing costs, and ensures extremely high timing and position coordination accuracy between functional steps through mechanical linkage, thereby ultimately achieving highly reliable automated detection.

[0052] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A visual inspection system for wire harness concentricity and circumferential inspection of wire harness ends, characterized in that: It includes an isolation wall (3), a wire harness clamp (2), a prism assembly (4), and a vision camera (5); the wire harness clamp (2) and the prism assembly (4) are located on the outside and inside of the isolation wall (3), respectively, and the vision camera (5) is located on the side of the prism assembly (4) away from the isolation wall (3); The isolation wall (3) has a wire harness insertion port (8) with the wire harness insertion port (8) being coaxial with the axis of the vision camera (5). When the wire harness end (1a) of the wire harness (1) is inserted coaxially from the wire harness insertion port (8) and reaches the inside of the isolation wall (3), the wire harness clamp (2) outside the wire harness insertion port (8) can clamp the part of the wire harness (1) near the wire harness end (1a). The prism assembly (4) includes at least six total reflection prism units (10) arranged in a circular array around the axis of the wire harness insertion port (8). When the wire harness end (1a) is inserted from the wire harness insertion port (8) and reaches the inside of the isolation wall (3), each total reflection prism unit (10) is evenly distributed around the wire harness end (1a), and the side of each total reflection prism unit (10) near the wire harness end (1a) is the prism total reflection surface (10a). Within the enclosure of the six total reflection prism units (10), there is a conical optical ring wall (13) coaxial with the wire harness insertion port (8). The thick end of the conical optical ring wall (13) faces the vision camera (5). The conical optical ring wall (13) is made of non-transparent material. The conical optical ring wall (13) has a light-transmitting window (12) cut out in a section near the thin end of its own cone along the direction of the generatrix of the cone. A coaxial reference ring (14) is integrally mounted on the narrow end of the conical optical ring wall (13), and a rotating ring (50) is integrally mounted on the thick end of the conical optical ring wall (13). The outer ring of the rotating ring (50) is rotatably mounted on the floating ring (16) via a bearing (15). The inner ring of the rotating ring (50) is provided with a transmission gear along the contour array. A gear drive motor is mounted on the floating ring 16. The gear at the output end of the gear drive motor meshes with the transmission gear of the inner ring of the rotating ring (50), thereby driving the rotating ring (50) and the conical optical ring wall (13) to actively rotate along their own axis. During the rotation of the conical optical ring wall (13) around its own axis, the light transmission window (12) corresponds to each total internal reflection prism in turn. The prism total reflection surface (10a) of element (10), and the prism total reflection surface (10a) that does not correspond to the light transmission window (12) are all optically isolated from the end of the wire bundle (1a) by the conical optical ring wall (13); the image on the side of the end of the wire bundle (1a) is projected onto the corresponding prism total reflection surface (10a) through the light transmission window (12), and enters the field of view of the vision camera (5) after being reflected by the prism total reflection surface (10a); the floating ring 16 is connected to the isolation wall 3 through several telescopic devices 7 parallel to the axis of the conical optical ring wall 13. Under the drive of the telescopic devices 7, the floating ring (16) and the conical optical ring wall (13) can move closer to or away from the isolation wall (3) as a whole; The prism assembly (4) is located in a circular array of three sets of wire harness end constraint units (9) arranged around the axis of the conical optical ring wall (13). Each set of constraint units (9) is located in the gap between two adjacent total reflection prism units (10). Any single set of wire harness end constraint units (9) includes a roller arm (17), a constraint roller (11), a guide rod (20), a ball guide sleeve (19), a thrust spring (21), a universal ball rod (22), and a floating seat (18) extending radially along the coaxial reference ring (14). The floating seat (18) slides against the inner wall of the isolation wall (3). A roller arm (17) is fixedly connected along the length of the end of the floating seat (18) near the axis of the coaxial reference ring (14). A constraint roller (11) is rotatably mounted at the end of the roller arm (17). A guide rod (20) is fixedly connected along the length of the end of the floating seat (18) away from the axis of the coaxial reference ring (14). The guide rod (20) is coaxially guided and fitted onto the ball guide sleeve (19). The guide sleeve (19) is fixed on the isolation wall (3). A thrust spring (21) is provided between the ball guide sleeve (19) and the ball guide sleeve (19). The thrust spring (21) generates a thrust on the floating seat (18). A universal ball rod (22) is fixedly connected to the floating seat (18). A universal ball (23) is rotatably provided at the end of the universal ball rod (22). The axis of the universal ball rod (22) is perpendicular to the generatrix at the intersection of the outer cone surface of the conical optical ring wall (13).

2. The wire harness concentricity and wire harness end circumferential visual inspection system according to claim 1, characterized in that: Taking any total internal reflection prism unit (10) as an example, the side image of the wire harness end (1a) near the total internal reflection prism unit (10) is reflected by the total internal reflection surface (10a) of the prism of the total internal reflection prism unit (10) and enters the field of view of the vision camera (5); at the same time, the vision camera (5) can also directly capture the end image of the wire harness end (1a) along the axial direction.

3. The wire harness concentricity and wire harness end circumferential visual inspection system according to claim 2, characterized in that: In the initial state, each thrust spring (21) stores elastic potential energy, and the universal ball (23) rolls tangentially with the outer conical surface of the thick end of the conical optical ring wall (13). During the rotation of the conical optical ring wall (13) along the axis, the universal ball (23) always rolls with the outer conical surface of the conical optical ring wall (13). In the initial state, the three constraint rollers (11) of the three sets of wire harness end constraint units (9) are arranged in a circumferential array and are far apart from each other. The area enclosed by the three constraint rollers (11) can freely pass through the wire harness end (1a).

4. The wire harness concentricity and wire harness end circumferential visual inspection system according to claim 3, characterized in that: Each prism's total reflection surface (10a) forms a 45° angle with the axis of the vision camera (5).

5. The working method of the wire harness concentricity and wire harness end circumferential visual inspection system according to claim 4, characterized in that: The wire harness end (1a) of the wire harness (1) is inserted coaxially from the wire harness end insertion port (8) and reaches the inside of the isolation wall (3). The wire harness clamp (2) clamps the part of the wire harness (1) near the wire harness end (1a) to perform initial positioning and shaping of the wire harness (1). The conical optical ring wall (13) rotates around its own axis, and the vision camera (5) successively acquires images from the six directions of the side of the wire harness end (1a) and performs optical detection on the six directions of the side of the wire harness end (1a). The gear-driven motor drives the conical optical ring wall (13) to rotate adaptively around its own axis through meshing transmission, so that the light-transmitting window (12) rotates to avoid the three sets of wire harness end constraint units (9). The floating ring (16) and the conical optical ring wall (13) move away from the isolation wall (3) as a whole; then the vision camera (5) captures images of the end of the wire harness (1a) and the coaxial reference ring (14) along the axial direction. The vision system first compares the circumferential profile of the end of the wire harness (1a) with the coaxiality of the coaxial reference ring (14), and then compares the coaxiality between the wire core of the end of the wire harness (1a) and the circumferential profile of the end of the wire harness.

Images