Fender multi-angle adjustment assembly system fused with machine vision

Abstract

The present application relates to the field of machine vision and automatic assembly, in particular to a mudguard multi-angle adjusting assembly system fusing machine vision, comprising a visual detection module, a posture adjusting module, a stress detection module, a vibration judgment module, a state judgment module, a fastening module and a coordination control module; collecting hole position area and edge fitting area images, generating visual effective marks, and outputting hole position deviation and contour stability; combining the position change amount of the position encoder, motor current, estimated torque and following error to obtain stress indicators and effective displacement marks; switching among coarse positioning, fitting, fastening and abnormal back-off states according to the hole position deviation, contour stability, stress indicators, effective displacement marks and visual effective marks, realizing multi-angle closed-loop adjusting assembly of the mudguard, and reducing repeated adjustment and deviation repetition.

Description

Technical Field

[0001] This invention relates to the field of machine vision and automated assembly technology, specifically to a multi-angle adjustment assembly system for mudguards that integrates machine vision. Background Technology

[0002] Current mudguard assembly mainly relies on machine vision technology to perform non-contact detection of hole areas and edges to guide posture adjustment and installation. However, due to the characteristics of mudguards such as uneven local stiffness, easy edge deformation, scattered hole positions, and susceptibility to vibration interference, relying solely on visual recognition for assembly control has the following technical problems: misjudgments often occur where the hole positions are judged to be aligned but the actual edges are not in contact; and due to the lack of force feedback, abnormal increases in local force cannot be detected in time, making it very easy for the workpiece to shift again during the fastening process. Meanwhile, in existing assembly systems, visual inspection, posture execution, force judgment and fastening control are often isolated from each other, lacking a continuous judgment and coordinated switching mechanism around the same assembly state, which makes it difficult for the system to balance assembly accuracy and stability under multi-angle adjustment and abnormal working conditions. Therefore, existing technologies urgently need a multi-state collaborative mudguard assembly control scheme to comprehensively handle hole position deviation, contour fit, posture and force changes, and solve problems such as poor fit, abnormal force and fastening offset caused by single vision control and multi-module fragmentation. Summary of the Invention

[0003] The purpose of this invention is to provide a multi-angle adjustment assembly system for mudguards that integrates machine vision. This avoids problems such as visual alignment but actual edge misalignment, unrecognized local stress increases, inaccurate displacement, and re-offset during fastening caused by relying solely on image recognition results for assembly control during the assembly process. Furthermore, it makes it easier to comprehensively process hole position deviations, contour fit status, posture changes, stress changes, and fastening processes, thereby achieving precise adjustment, stable fit, and reliable fastening during the mudguard assembly process.

[0004] The objective of this invention can be achieved through the following technical solutions: A multi-angle adjustment and assembly system for mudguards integrating machine vision is used for multi-angle adjustment and assembly of workpieces to be assembled, including mudguards, comprising: The vision inspection module is used to acquire images of the hole area and edge mating area of ​​the workpiece to be assembled, generate visually valid marks based on the image clarity and integrity, and output the vision inspection results of hole deviation and contour stability. The attitude adjustment module includes a multi-axis drive motor, a clamping mechanism, and a position encoder. The multi-axis drive motor is used to drive the clamping mechanism to adjust the attitude of the workpiece to be assembled, and the position encoder is used to output the position change. The force detection module is connected to a multi-axis drive motor to obtain the motor current, estimated torque, and following error of the multi-axis drive motor. Based on the normalized motor current, estimated torque, and following error, the force index and the force change rate are obtained. The vibration judgment module generates an effective displacement flag when the amplitude of the position change reaches the minimum effective displacement threshold corresponding to the preset displacement measurement accuracy and the direction is consistent within a continuously set sampling period. The status judgment module is used to switch the assembly status between coarse positioning, fitting, fastening and abnormal retreat states according to preset status switching conditions based on hole position deviation, contour stability, stress index, effective displacement mark and visual effective mark. The fastening module includes a tightening actuator for performing fastening when the assembly state is switched to the fastening state; The coordination and control module is communicatively connected to the vision inspection module, posture adjustment module, force detection module, vibration judgment module, status judgment module, and fastening module, respectively, and sends control commands to the posture adjustment module and fastening module according to the assembly status.

[0005] Furthermore, the vision inspection module includes an industrial camera, a light source, a trigger controller, and an image processing unit; The industrial camera acquires images under the control of the trigger controller; The image processing unit is used to generate a visually valid label when the image sharpness reaches a preset sharpness threshold and the image integrity reaches a preset integrity threshold. The image processing unit extracts the center coordinates of the hole and the center coordinates of the target installation based on the image and calculates the hole position deviation; The image processing unit is used to determine the stability of the contour based on the edge fitting error within a continuous sampling period. When the edge fitting error is less than a preset fitting threshold, the contour is determined to be stable. When the edge fitting error is greater than or equal to the preset fitting threshold, the contour is determined to be unstable. The hole position deviation, contour stability, and visually valid mark are sent to the coordination control module.

[0006] Furthermore, the multi-axis drive motor includes a pitch adjustment axis, a yaw adjustment axis, and a roll adjustment axis, and the attitude adjustment module also includes a servo driver, which outputs the following error. The position encoder sends the adjusted position to the coordination control module, which compares the preset target attitude with the adjusted position to obtain the attitude error vector; The coordination control module converts the orifice position deviation into an orifice position deviation vector, and constructs the normalized force components corresponding to the pitch adjustment axis, yaw adjustment axis and yaw adjustment axis into a normalized force feedback vector. Based on the orifice position deviation vector, attitude error vector and normalized force feedback vector, the attitude adjustment module controls the attitude adjustment module to perform attitude adjustment.

[0007] Furthermore, the force detection module performs zero-point compensation and low-pass filtering on the acquired motor current, estimated torque, and following error, and normalizes the motor current, estimated torque, and following error. The normalized motor current, estimated torque, and following error are weighted and summed according to preset fixed weighting coefficients to obtain the stress index. The sum of the preset fixed weighting coefficients is 1. The force detection module calculates the force change rate based on the force index of adjacent sampling periods, and sends an abnormal force flag to the coordination control module when the force index is greater than or equal to the preset force threshold or the force change rate is greater than or equal to the preset change rate threshold.

[0008] Furthermore, the preset state switching conditions of the state judgment module include: When the hole position deviation is not greater than the preset first hole position threshold and the force index reaches the preset first force threshold within the number of consecutive control cycles, the state judgment module will switch the coarse positioning state to the fitting state. When the hole position deviation is not greater than the preset second hole position threshold, the contour stability is stable, the force index continuously reaches the preset second force threshold, the effective displacement mark is valid and the visual effective mark is valid, the fastening condition is determined to be met, and the state judgment module switches the fitting state to the fastening state. The first hole position threshold is greater than the second hole position threshold; the first force threshold is less than the second force threshold; if the hole position deviation continues to exceed the first hole position threshold for more than a preset time, the state judgment module switches to the abnormal retreat state, and the coordination control module controls the attitude adjustment module to retreat to the initial position.

[0009] Furthermore, in the fit state, the coordination control module generates a pre-compensation displacement vector based on the hole position deviation vector obtained by converting the hole position deviation and the normalized force feedback vector composed of the normalized force components obtained by converting the force index corresponding to each adjustment shaft of the multi-axis drive motor. The coordination control module limits the magnitude of the pre-compensated displacement vector to no greater than the preset maximum allowable stroke of the clamping mechanism; After the attitude adjustment module performs pre-compensation displacement vector, the coordination control module reacquires the visual detection results and force indicators within the set stability confirmation time, and allows the fastening module to operate when the fastening conditions are met.

[0010] Furthermore, the vibration judgment module performs directional consistency judgment on the position change within a continuously set sampling period; When the amplitude of the position change is not less than the minimum effective displacement threshold corresponding to the preset displacement measurement accuracy, and the proportion of sampling times with the same direction of position change within a continuously set sampling period reaches a preset ratio, the effective displacement flag is determined to be valid; otherwise, the effective displacement flag is determined to be invalid. When the effective displacement flag is invalid, the coordination control module prohibits the attitude adjustment module from performing attitude adjustment with a displacement greater than the preset step size. When the effective displacement flag is continuously invalid and the force index increases, the attitude adjustment speed is switched to the preset low speed level, and the stabilization confirmation time is switched to the preset extended value.

[0011] Furthermore, the fastening module also includes a fastening driver, a torque detection unit, and an angle detection unit; the fastening module performs fastening according to the low-speed contact section, the pre-tightening section, the stability confirmation section, and the final fastening section; In the low-speed contact section, the tightening actuator runs at the first speed until the tightening torque reaches the contact threshold; in the pre-tightening section, it runs at the second speed until the tightening torque reaches the pre-tightening threshold; in the stabilization confirmation section, the tightening torque is kept stable for a preset time; in the final tightening section, it runs until the tightening angle reaches the target tightening angle. After each tightening stage is completed, the current stage tightening torque and tightening angle obtained by the torque detection unit and angle detection unit are sent to the coordination control module. When the clamping torque is greater than or equal to the current stage's preset torque limit, or when the clamping torque and clamping angle deviate from the preset torque range and preset angle range, the coordination control module stops clamping, controls the attitude adjustment module to reduce clamping constraints, and switches to the abnormal retreat state.

[0012] Furthermore, the coordination control module sends a global sampling command to the vision detection module and prohibits the fastening module from moving in the coarse positioning state; in the fitting state, it sends a local area sampling command to the vision detection module; and in the fastening state, it maintains the target position of the attitude adjustment module unchanged and makes the attitude adjustment module perform preset damping holding control. When a visually valid marker becomes invalid for more than a preset number of cycles, the coordination control module pauses the attitude adjustment module's action and re-triggers the visual detection module. When the preset visual recovery time limit is exceeded, it switches to the abnormal rollback state. When the fastening is completed and the hole position deviation, stress index, adjustment position and fastening torque are all within the corresponding preset threshold range, the coordination control module sends an assembly qualified signal to the host computer and stores the assembly data.

[0013] The beneficial effects of this invention are: 1. This invention acquires images of the hole location area and edge fitting area using an industrial camera, light source, trigger controller, and image processing unit. Based on image clarity, target integrity, and edge fitting error, it generates visually valid markers and contour stability results. Furthermore, it improves the stability of hole location recognition and fitting judgment through candidate contour screening and continuous sampling. The hole location deviation is converted from image plane deviation into a three-axis hole location deviation vector corresponding to pitch, yaw, and roll adjustment axes. Combined with attitude error vector and normalized force feedback vector, it generates attitude adjustment commands with clear step size, direction, and speed axis by axis, thereby improving the accuracy and controllability of multi-angle adjustment of the mudguard. 2. This invention performs zero-point compensation, low-pass filtering, and normalization on the motor current, estimated torque, and following error of each adjustment shaft. It forms axial force components and comprehensive force indicators according to fixed weights, and identifies abnormal forces by combining the force change rate. This can reduce misjudgments caused by no-load offset, instantaneous fluctuations, and local force masking. Through continuous periodic joint judgment of hole position deviation, contour stability, force indicators, effective displacement marks, and visual effective marks, the assembly state can be switched in an orderly manner between coarse positioning state, fitting state, fastening state, and abnormal retreat state, avoiding assembly conclusions based on a single image or feedback. 3. In the fit state, this invention generates a limited-amplitude pre-compensation displacement vector based on the triaxial hole position deviation vector and the normalized force feedback vector, and determines the force release direction based on the relationship between the displacement direction and the force change, reducing the flexible deformation and repeated adjustments caused by visual alignment but edge misfitting and local force increase; by judging the minimum effective displacement and direction consistency of the position change, the reliability of the actual displacement after posture adjustment is confirmed, and when the displacement is invalid and the force increases, large step size adjustment is restricted, the adjustment speed is reduced and the stability confirmation time is extended, reducing the impact of mechanical vibration, encoder jitter and gap backlash on assembly judgment; 4. After meeting the conditions of hole alignment, contour stability, continuous fit, effective displacement, and visual effectiveness, this invention performs segmented fastening according to the stages of low-speed contact, pre-tightening, stability confirmation, and final fastening. The process is monitored in conjunction with torque and angle range. In case of abnormality, fastening is stopped, clamping constraints are reduced, and abnormal retreat is performed. At the same time, global sampling, local area sampling, and attitude damping maintenance control are switched according to different assembly states. When the vision is continuously invalid, the attitude action is paused and the detection is retried. After fastening is completed, the hole deviation, force index, adjustment position, and fastening torque are checked and the assembly data is stored, thereby improving the accuracy, fit stability, fastening reliability, and safety under abnormal working conditions of the mudguard assembly process. Attached Figure Description

[0014] Other features, objects, and advantages of the invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 A block diagram of a multi-angle adjustment assembly system for mudguards that incorporates machine vision, according to an embodiment of the present disclosure, is shown. Detailed Implementation

[0015] 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, and 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.

[0016] Please see Figure 1 A multi-angle adjustment and assembly system for mudguards integrating machine vision is used for multi-angle adjustment and assembly of workpieces to be assembled, including mudguards, comprising: The vision inspection module is used to acquire images of the hole area and edge mating area of ​​the workpiece to be assembled, generate visually valid marks based on the image clarity and integrity, and output the vision inspection results of hole deviation and contour stability. The attitude adjustment module includes a multi-axis drive motor, a clamping mechanism, and a position encoder. The multi-axis drive motor is used to drive the clamping mechanism to adjust the attitude of the workpiece to be assembled, and the position encoder is used to output the position change. The force detection module is connected to a multi-axis drive motor to obtain the motor current, estimated torque, and following error of the multi-axis drive motor. Based on the normalized motor current, estimated torque, and following error, the force index and the force change rate are obtained. The vibration judgment module generates an effective displacement flag when the amplitude of the position change reaches the minimum effective displacement threshold corresponding to the preset displacement measurement accuracy and the direction is consistent within a continuously set sampling period. The status judgment module is used to switch the assembly status between coarse positioning, fitting, fastening and abnormal retreat states according to preset status switching conditions based on hole position deviation, contour stability, stress index, effective displacement mark and visual effective mark. The fastening module includes a tightening actuator for performing fastening when the assembly state is switched to the fastening state; The coordination and control module is connected to the vision inspection module, posture adjustment module, force detection module, vibration judgment module, status judgment module and fastening module respectively, and sends control commands to the posture adjustment module and fastening module according to the assembly status. In one preferred embodiment, the vision inspection module includes an industrial camera, a light source, a trigger controller, and an image processing unit; The industrial camera acquires images under the control of the trigger controller; The image processing unit is used to generate a visually valid label when the image sharpness reaches a preset sharpness threshold and the image integrity reaches a preset integrity threshold. The image processing unit extracts the center coordinates of the hole and the center coordinates of the target installation based on the image and calculates the hole position deviation; The image processing unit is used to determine the stability of the contour based on the edge fitting error within a continuous sampling period. When the edge fitting error is less than a preset fitting threshold, the contour is determined to be stable. When the edge fitting error is greater than or equal to the preset fitting threshold, the contour is determined to be unstable. The hole position deviation, contour stability, and visually valid mark are sent to the coordination control module. The multi-axis drive motor includes a pitch adjustment axis, a yaw adjustment axis, and a roll adjustment axis. The attitude adjustment module also includes a servo driver, which outputs the following error. The position encoder sends the adjusted position to the coordination control module, which compares the preset target attitude with the adjusted position to obtain the attitude error vector; The coordination control module converts the orifice position deviation into an orifice position deviation vector, and constructs the normalized force components corresponding to the pitch adjustment axis, yaw adjustment axis and yaw adjustment axis into a normalized force feedback vector. Based on the orifice position deviation vector, attitude error vector and normalized force feedback vector, the attitude adjustment module controls the attitude adjustment module to perform attitude adjustment.

[0017] This embodiment is used for mudguard assembly; after the workpiece to be assembled is clamped by the clamping mechanism, the coordination control module first sends a sampling command to the vision inspection module, and the industrial camera acquires images of the hole area and the edge fitting area under the control of the trigger controller. The visual validity indicator is a validity status parameter generated by the image processing unit based on the image clarity and target integrity meeting the assembly judgment requirements; the hole position deviation is the offset vector between the currently identified hole position center and the target installation center; the contour stability status characterizes the state in which the edge fitting area is within a preset allowable range within a continuously set sampling period; The force index refers to the comprehensive characterization quantity formed by the motor current, estimated torque and following error after compensation, filtering and normalization; the effective displacement indicator refers to the reliable displacement result formed when the position change reaches the minimum effective displacement condition and the direction is consistent within a continuously set sampling period. In this embodiment, the adjustment position is the current position of each attitude adjustment axis output by the position encoder, which is used to calculate the attitude error vector; the position change is the position increment obtained by subtracting the adjustment position between adjacent sampling periods, which is used by the vibration judgment module to generate an effective displacement flag. Furthermore, in this embodiment, the same control cycle refers to the comprehensive judgment made after reading the most recent valid visual result and the most recent encoder, servo driver and force detection results in the same decision window, allowing the time difference between the exposure time of the industrial camera and the sampling time of the motor to be within the preset asynchronous tolerance range; At the beginning of the assembly process, the coordination control module sets the assembly status to coarse positioning and prohibits the fastening module from operating; the vision inspection module acquires images of the current mudguard hole area. The image processing unit performs sharpness and target integrity assessments on the acquired images. Sharpness is one of the key parameters. The variance is calculated based on the Laplace operator, and the calculation formula is as follows: in, and These are the width and height of the image, respectively. and These are the horizontal and vertical coordinate indices of the pixel, respectively. For pixels The Laplace response value at that point, The arithmetic mean of the Laplacian response values ​​over the entire image region; target integrity. Based on the calculation of the contour perimeter continuity, the formula is: in, This represents the length of the currently extracted continuous hole profile. The preset standard hole profile length; When the image edges are clear, the hole contours are continuous, and the degree of occlusion does not exceed the preset conditions, the image processing unit generates a visually valid mark. When the clarity is insufficient or the target area is missing, the visual valid mark is invalid. At this time, the visual result is only used as the basis for resampling and will not be included in the subsequent posture correction calculation. The center coordinate of the hole is preferably obtained by extracting the edge of the hole contour and then finding the geometric center of the contour. The target installation center coordinate is given by the pre-stored installation reference of the workpiece model corresponding to the current workstation. When multiple candidate contours exist in the same hole location area, the image processing unit filters them sequentially according to contour closure, area range, and distance continuity with the recognition result of the previous control cycle, so as to ensure that the hole location deviation calculation is performed on the same target hole location. When the visually valid marker is valid, the image processing unit extracts the coordinates of the hole center and the target installation center, and calculates the two-dimensional vector of the hole position deviation. : in, The extracted coordinates of the current hole center. The target is installed with center coordinates; its modulus is calculated using the following formula: in, It reflects the degree of deviation between the current hole position and the target installation position; in order to facilitate subsequent attitude adjustment, the coordination control module converts the hole position deviation into a hole position deviation vector; this vector corresponds to the offset direction and offset magnitude of the workpiece to be assembled on the image plane, and is used to characterize the geometric deviation vector of the mudguard relative to the installation position. Furthermore, in order to make the geometric deviation correspond in dimension to the control quantities of the pitch adjustment axis, yaw adjustment axis and roll adjustment axis, the coordination control module first extracts the two-dimensional hole position deviation vector of the image plane, and simultaneously extracts the distance difference between the left and right edges of the hole position area and the reference edge. Based on the nonlinear transformation matrix of the camera field of view and the tool coordinate system pre-calibrated at the current station, the above two-dimensional vector features and distance difference features are jointly mapped into three-axis equivalent correction quantities to obtain the three-axis hole position deviation vector used for control calculation. The conversion relationship remains fixed under the same workstation and the same workpiece model, and is used to map the deviation direction of the image plane to the target correction component of each attitude adjustment axis; In this embodiment, the generation rule for the three-axis hole position deviation vector is as follows: the left-right deviation of the image plane is fixedly mapped to the yaw adjustment axis correction component, the up-down deviation of the image plane is fixedly mapped to the pitch adjustment axis correction component, and the skew direction corresponding to the distance difference between the left and right edges of the hole position area and the reference edge is fixedly mapped to the yaw adjustment axis correction component. When the image plane deviation is positive, the corresponding attitude axis is corrected in the positive direction; when the image plane deviation is negative, the corresponding attitude axis is corrected in the negative direction. When the difference between the left and right edges of the hole position area is zero or within the preset non-response range, the yaw adjustment axis correction component is recorded as zero; the preset non-response range is determined by the image resolution and the station repetitive positioning error; thus, after the two-dimensional hole position deviation enters the coordination control module, it is decomposed into the yaw direction correction amount, pitch direction correction amount and yaw direction correction amount to perform attitude control. Meanwhile, the image processing unit extracts edges from the edge-fitting area and calculates the fitting error for the edge results within a continuously set sampling period; Edge fitting error refers to the degree of deviation between the edge contour extracted in the current cycle and the reference fitting contour. The reference fitting contour is preferably the edge contour pre-stored in the qualified assembly state corresponding to the current station, or the reference contour obtained by fitting the edge contour of multiple consecutive stable sampling cycles. When the fitting error is less than the preset fitting threshold, the contour is considered stable; when the error continues to exceed the fitting threshold, the contour is considered unstable. The fitting threshold is not a fixed absolute value, but is determined by the workpiece edge shape tolerance, visual resolution, and the upper limit of contour fluctuation in multiple successful assembly samples. Its value is within the range that can distinguish between stable fit and occlusion distortion. This implementation uses the absolute values ​​of the normal distances from multiple sampling points on the edge extracted in the current cycle to the corresponding positions of the reference fitting contour as local deviations, and uses the average value of each local deviation as the edge fitting error for that cycle. The mathematical calculation formula is as follows: in, This represents the edge fitting error. This represents the total number of valid, unobstructed sampling points extracted from the current edge. For the first The normal distance from each valid sampling point to the corresponding position of the reference fitting contour; When a sampling point cannot obtain the corresponding edge due to occlusion, the point will not participate in the average calculation. If the proportion of missing points exceeds the preset integrity threshold, the stability of the contour in this period will be directly judged as unstable and the visually valid mark will be set to invalid. The attitude adjustment module consists of a pitch adjustment axis, a yaw adjustment axis, and a roll adjustment axis, each of which is connected to a corresponding multi-axis drive motor. Each drive motor is connected to a servo driver and a position encoder. The position encoder outputs the current position of each adjustment axis, and the servo driver outputs the following error. The attitude error vector refers to the set of errors obtained by comparing the preset target attitude with the current position, which corresponds to the deviation in the pitch, yaw and roll directions respectively. After receiving the adjusted position sent by the position encoder, the coordination control module first calculates the attitude error vector, and then represents the force index sent by the force detection module as a normalized force feedback vector. In this embodiment, the normalized force feedback vector is composed of the normalized force components corresponding to the pitch adjustment axis, yaw adjustment axis and yaw adjustment axis, and represents the contact trend parameters in the direction of each attitude adjustment axis. The stress index is a scalar result that further integrates the above-mentioned axial components, and is used for state judgment and abnormal stress determination. In this embodiment, the normalized force feedback vector is used to characterize the contact trend in the corresponding direction of each attitude adjustment axis. It, along with the three-axis hole position deviation vector and the attitude error vector, participate in the attitude adjustment decision in the same control cycle. However, the physical meanings of the three correspond to the contact trend, image geometric deviation and actuator attitude deviation, respectively, and they do not replace each other. In the coarse positioning state, the coordination control module generates the attitude adjustment command for this cycle based on the three-axis hole position deviation vector, attitude error vector, and normalized force feedback vector. The adjustment logic is: when the hole position deviation is greater than the preset upper limit threshold and the force index is less than the preset lower limit threshold, hole position deviation correction is performed. When the hole position deviation is less than or equal to the preset upper limit threshold and the force index is greater than or equal to the preset lower limit threshold, the forward advance of the attitude adjustment axis is limited; when the attitude error direction is inconsistent with the hole position deviation direction, attitude correction is performed according to the current adjustment position parameters. Furthermore, the attitude adjustment command is generated according to the step size method: first, based on the relationship between the hole position deviation magnitude value and the first hole position threshold and the second hole position threshold, the adjustment step size is divided into three levels: large step size, medium step size and small step size. Then, based on the magnitude of the component in the corresponding direction of the normalized force feedback vector, the original step size is maintained, reduced by one level, or directly limited to zero; the adjustment direction of the pitch, yaw, and roll adjustment axes is determined by the sign of the attitude error vector. Preferably, a large step size is used when the hole position deviation magnitude is greater than the first hole position threshold, a medium step size is used when the hole position deviation magnitude is not greater than the first hole position threshold but greater than the second hole position threshold, and a small step size is used when the hole position deviation magnitude is not greater than the second hole position threshold. When the normalized force feedback component in the corresponding direction reaches the interval corresponding to the second force threshold, the step size in that direction is reduced by at least one level; when an abnormal force indicator appears, the target attitude increment in that direction is recorded as zero and the current position is maintained for verification. This implementation method limits the control sequence of each axis as follows: First, the three-axis hole position deviation vector, attitude error vector and normalized force feedback vector are taken as components in the three directions of pitch, yaw and roll respectively; then, the axis is judged one by one to determine whether there is an abnormal force indicator in the direction. If there is, the axis will not output displacement command in this cycle. If the abnormal force flag is not triggered, it is determined whether the hole position deviation component of the shaft falls into the corresponding preset non-response range. If it falls into the range, the minimum step size reset is performed according to the attitude error component. If it does not fall into the range, the adjustment command is output according to the direction of the hole position deviation component. If the direction of the hole position deviation component is opposite to the direction of the attitude error component, then the minimum step size attitude reset of one cycle is executed first, and the vision result is reread in the next control cycle to determine whether to continue hole position correction. Therefore, the coordination control module sends the target attitude increment and adjustment speed command of each adjustment axis to the attitude adjustment module, and the multi-axis drive motor drives the clamping mechanism to move the mudguard to make attitude changes in the corresponding direction. The target attitude increment is generated independently for each axis and is limited by the maximum adjustment increment per cycle. The maximum adjustment increment per cycle is jointly limited by the allowable stroke of the clamping mechanism, the safety clearance of the workpiece edge, and the current assembly state, so as to keep the attitude adjustment continuous and controllable. The speed adjustment corresponds one-to-one with the step size settings: large step size corresponds to high speed, medium step size corresponds to medium speed, and small step size corresponds to low speed. After each attitude adjustment is completed, the position encoder outputs a new position change, the force detection module updates the motor current, estimated torque and following error synchronously, and the vision detection module re-acquires the image; the state judgment module reads the hole position deviation, contour stability, force index, effective displacement mark and visual effective mark simultaneously in the same control cycle, and determines whether the state switching conditions are met. The system executes the control loop of data acquisition, judgment, adjustment, and verification in each control cycle; The preset threshold is set according to the assembly process boundary; the threshold used to judge the hole position deviation comes from the hole position tolerance, the repeatability error of the clamping mechanism, and the size of the installation window; The sharpness and integrity thresholds used for visual effectiveness are derived from the imaging resolution of the industrial camera under current lighting, exposure mode, and target occlusion conditions; the fitting threshold used for contour stability judgment is derived from the edge fluctuation range in consecutive successfully assembled samples. The above thresholds were all determined by sample assembly and calibration. The preferred value range was one that could ensure stable hole position recognition without causing frequent resampling due to overly strict thresholds. In the above way, the visual inspection results no longer determine the assembly action alone, but work together with the three-axis attitude position, servo following error and force feedback. The reason for this is that the mudguard is a plate with uneven local stiffness. Relying solely on the hole position image for centering can easily result in a situation where the visual alignment is close but the edges are not yet in contact or the local stress has increased significantly. This implementation uses a three-axis hole position deviation vector to describe the geometric correction requirements in the same dimension as the attitude axis, an attitude error vector to describe the current deviation of the actuator, a normalized force feedback vector to describe the contact trend, and a force index to perform stage judgment and anomaly judgment functions. The attitude adjustment command is uniformly issued by the coordination control module, thereby reducing the problems of repeated adjustments and repeated deviations.

[0018] In one preferred embodiment, the force detection module performs zero-point compensation and low-pass filtering on the acquired motor current, estimated torque, and following error, and normalizes the motor current, estimated torque, and following error. The normalized motor current, estimated torque, and following error are weighted and summed according to preset fixed weighting coefficients to obtain the stress index. The sum of the preset fixed weighting coefficients is 1. The force detection module calculates the force change rate based on the force index of adjacent sampling periods, and sends an abnormal force flag to the coordination control module when the force index is greater than or equal to the preset force threshold or the force change rate is greater than or equal to the preset change rate threshold. The preset state switching conditions of the state judgment module include: when the hole position deviation is not greater than the preset first hole position threshold and the force index reaches the preset first force threshold within the number of consecutively set control cycles, the state judgment module will switch the coarse positioning state to the fitting state. When the hole position deviation is not greater than the preset second hole position threshold, the contour stability is stable, the force index continuously reaches the preset second force threshold, the effective displacement mark is valid and the visual effective mark is valid, the fastening condition is determined to be met, and the state judgment module switches the fitting state to the fastening state. The first hole position threshold is greater than the second hole position threshold; the first force threshold is less than the second force threshold; if the hole position deviation continues to be greater than the first hole position threshold for more than a preset time, the state judgment module switches to the abnormal retreat state, and the coordination control module controls the attitude adjustment module to retreat to the initial position. In the fit state, the coordination control module generates a pre-compensation displacement vector based on the hole position deviation vector obtained by converting the hole position deviation and the normalized force components obtained by converting the force index corresponding to each adjustment shaft of the multi-axis drive motor. The coordination control module limits the magnitude of the pre-compensated displacement vector to no greater than the preset maximum allowable stroke of the clamping mechanism; After the attitude adjustment module performs pre-compensation displacement vector, the coordination control module reacquires the visual detection results and force indicators within the set stability confirmation time, and allows the fastening module to operate when the fastening conditions are met. The vibration judgment module judges the directional consistency of the position change within a continuously set sampling period. When the amplitude of the position change is not less than the minimum effective displacement threshold corresponding to the preset displacement measurement accuracy, and the proportion of sampling times with the same position change direction within a continuously set sampling period reaches a preset ratio, the effective displacement flag is determined to be valid; otherwise, the effective displacement flag is determined to be invalid. When the effective displacement flag is invalid, the coordination control module prohibits the attitude adjustment module from performing attitude adjustment with a displacement greater than the preset step size. When the effective displacement flag is continuously invalid and the force index increases, the attitude adjustment speed is switched to the preset low speed level, and the stabilization confirmation time is switched to the preset extended value.

[0019] This implementation focuses on illustrating the coordination relationship between force judgment, state switching, pre-compensation, and vibration judgment; the force detection module is directly connected to the multi-axis drive motor and servo driver, and its input data includes motor current, estimated torque, and following error; The zero-point compensation configuration is to collect and record the reference compensation value of each channel when the fixture is unloaded or in the reference assembly preparation state, and to subtract the reference compensation value from the real-time sampling data during assembly control. Low-pass filtering uses a first-order discrete digital filtering algorithm to suppress high-frequency fluctuations in continuous sampled values. Its filtering formula is as follows: in, The time sequence number of the sampling period. This is the compensated input value for the current sampling period. This is the current filter output value. This is the output value of the previous filter cycle. The filter coefficients are set to (0,1) to extract low-frequency trend data of mudguard adhesion and force changes. After zero-point compensation and low-pass filtering, the force detection module normalizes the motor current, estimated torque and following error respectively, so that the three types of data enter the same dimension range. The normalized current feedback value reflects the change in drive load, the normalized torque feedback value reflects the mechanical output burden of the attitude axis, and the normalized following error reflects the deviation between the executed command and the motion. Normalization processing uses the upper and lower limits of the effective range determined by each channel under the calibration conditions for amplitude limiting conversion. Input data below the lower limit is assigned the value according to the lower limit of the effective range, and input data above the upper limit is assigned the value according to the upper limit of the effective range. Preferably, for any channel quantity First, limit its real-time value to Calculate the normalized result, then apply the formula: in, This is the real-time value of the channel quantity after amplitude limiting. and These are the lower and upper limits of the effective range of the channel under calibrated operating conditions, respectively. The range of values ​​is Its positive or negative sign is used to characterize the physical direction of the force feedback and following error of the attitude adjustment axis; when and If the results are the same but the conversion conditions are not met, the normalization result of the channel is recorded as 0 and recalibration is triggered. The channel will not participate in state switching before the recalibration is completed. Furthermore, the normalization process is performed independently and concurrently on the data channels corresponding to the pitch, yaw, and roll axes. The force detection module calculates the normalized force component of each attitude adjustment axis using the same fixed weight, specifically as follows: in, These represent the pitch control axis, yaw control axis, and roll control axis, respectively. , and These represent the normalized current feedback value, normalized torque feedback value, and normalized following error for the corresponding axis, respectively. , and For preset fixed weight coefficients, and ; Pitch, yaw and roll adjustment axes After being arranged in a fixed axis sequence, a normalized force feedback vector is formed, which is used to coordinate the axis-by-axis attitude adjustment of the control module. Three force indices are used for state assessment and abnormal force determination. The maximum value in the range; using the maximum value as the stress index can avoid the abnormal stress on a local attitude axis being masked by the averaging of other low-stress axes; Therefore, the normalized force feedback vector and the force index are derived from the same set of axial calculation results. The former retains the information of each axis direction, while the latter serves as a comprehensive scalar of the three-axis force state and is no longer calculated separately using different inputs or different weights. Furthermore, when determining the continuous attainment of the first and second force thresholds, the force index sequence generated by the same valid data set within the continuous control cycle shall be used as the standard; If the dominant axis that triggers the force index to reach the threshold in an adjacent control cycle switches between the pitch, yaw and roll axes, and the difference in the force index between the two cycles before and after the switch is greater than the preset dominant axis switching range, then the force establishment process is considered discontinuous, the current continuous count is cleared and re-accumulated. Only when the dominant axis remains unchanged, or when a switch occurs but the difference in force index is not greater than the preset dominant axis switching range, is it considered to be the same continuous bonding process; this can avoid the misjudgment of stable bonding simply because the maximum value continuously exceeds the threshold when the force peaks of the three attitude axes alternate in adjacent cycles. The weighting coefficients are determined based on the stiffness of the mudguard material, the transmission characteristics of the clamping mechanism, and the main sources of force response during assembly: when the workpiece's flexible deformation parameter is greater than the preset deformation threshold, the weighting coefficients of torque feedback and following error are increased; when the mechanism's inertial force parameter is greater than the preset inertial threshold, the weighting coefficients of current feedback and following error are increased. The weights are not arbitrarily assigned, but are determined based on the principle of being able to reliably distinguish between four working conditions: no load, initial contact, continuous bonding, and abnormal extrusion. They are used in a fixed manner at the same workstation and for the same workpiece model, and are not changed in real time during the assembly process. In this embodiment, the preset force threshold is configured as the upper limit parameter for safety judgment when the force detection module generates abnormal force flags; The first and second force thresholds are used by the state judgment module to identify the bonding stage and the fastening permission stage, which correspond to the assembly stage judgment. These three stages have different functions, and the first force threshold is lower than the second force threshold. The preset force threshold used for anomaly judgment is not lower than the second force threshold. The first force threshold, the second force threshold, and the preset force threshold all fall within the range of [value range missing]. The stress indices were compared and determined sequentially according to the distribution boundaries of the stress indices in the initial contact sample, stable fit sample, and abnormal compression sample. The force detection module also calculates the rate of force change based on the force indices of adjacent sampling periods; the rate of force change characterizes the smoothness of force increase; and the sampling period duration... When the force change rate is greater than 0, it is expressed as: in, The time sequence number of the sampling period. and These are the force indices for the current sampling period and the previous sampling period, respectively. This refers to the sampling period duration; when the system uses a fixed sampling period and When the force index remains unchanged, the difference between the force indexes of adjacent sampling periods can be directly compared with the preset rate of change threshold calibrated according to the same fixed sampling period. However, only one comparison method is selected and fixed for the same workstation. If the sampling timestamp is missing, duplicated, or... If the value is not greater than 0, the force change rate will not be calculated for this period, and the force change rate result for this period will be marked as invalid. The sample will be resampled and then the result will be judged again. When the stress index gradually increases within a continuously set sampling period and the rate of change does not exceed the preset rate of change threshold, it indicates that the mudguard and the mounting surface are establishing stable contact; when the stress index is less than the preset lower limit of stress and the rate of change of stress is greater than the preset rate of change threshold, it is determined that the system has entered the edge interference impact or attitude step fluctuation condition. When the stress index exceeds the preset stress threshold, it indicates that the workpiece may have entered an unacceptable compression state. When either the stress index exceeds the preset stress threshold or the effective stress change rate exceeds the preset change rate threshold, the stress detection module sends an abnormal stress flag to the coordination control module. Furthermore, if the normalized force feedback vector used for control and the force index used for state judgment have different timestamps within the same decision window, the coordinated control module extracts the filtered and normalized data of the most recent timestamp within the decision window to generate the normalized force feedback vector and the force index. The status judgment module simultaneously receives hole position deviation, contour stability, stress index, effective displacement indicator and visual effective indicator in each control cycle; this implementation adopts continuous control cycle judgment instead of directly switching the status based on a single sampling result. The first hole position threshold and the second hole position threshold are both derived from hole position assembly tolerance and clamping repeatability positioning error. The first hole position threshold is greater than the second hole position threshold and is used to distinguish between two different stages: when the installation position is close to being reached and when the alignment requirements before tightening have been met. The first and second force thresholds are both derived from the contact establishment load and the bonding stability load, with the first force threshold being less than the second force threshold, used to distinguish between initial bonding and stable bonding before fastening permission; Continuous achievement means maintaining the corresponding threshold conditions within multiple adjacent control cycles, without any abnormal force indicators or failure of visually valid indicators in between, thus ensuring that the state switching is based on a continuously established assembly trend, rather than a single fluctuation. If an abnormal force flag appears during continuous judgment, the current continuous count is cleared and the judgment restarts, thus maintaining consistent logic between abnormal force and stage switching. This implementation method uses an independent counting method: during coarse positioning to bonding, only the number of control cycles that simultaneously meet the conditions that the hole position deviation is not greater than the first hole position threshold and the force index reaches the first force threshold are accumulated. If any condition is not met, the accumulated number is cleared to zero. When transitioning from bonding to fastening, only the number of control cycles that simultaneously meet the following conditions is accumulated: "hole position deviation is not greater than the second hole position threshold, the contour stability is stable, the stress index reaches the second stress threshold, the effective displacement mark is valid, and the visual effective mark is valid." If any condition is not met, the accumulated number is cleared to zero. The abnormal backoff timer is continuously accumulated when the hole position deviation is continuously greater than the first hole position threshold, and reset to zero when the hole position deviation falls back to within the first hole position threshold; in this way, the state judgment module has fixed input conditions, fixed accumulation rules and fixed reset rules for each state switch. The number of continuously set control cycles, preset time, and stable confirmation time are all converted into integer cycles based on the control cycle length. The number of continuously set control cycles for coarse positioning to bonding is not less than 2 cycles, the number of continuously set control cycles for bonding to tightening is not less than 2 cycles, and the abnormal retreat preset time is not less than the total time corresponding to any of the above continuously set control cycles, so as to ensure that the tightening permission judgment is stricter than the stage entry judgment. Specifically, in the coarse positioning state, if the hole position deviation is not greater than the first hole position threshold, and the force index reaches the first force threshold within the continuously set number of control cycles, the state judgment module will switch the state to the fit state. When the hole position deviation reaches the preset lower limit range and the force establishment parameters meet the standard, the system determines that the workpiece is in the fitting position range. If the hole position deviation continues to exceed the first hole position threshold for more than a preset time, it is determined that the current adjustment process has not converged. The state judgment module switches to the abnormal retreat state, and the coordination control module controls the attitude adjustment module to retreat to the initial position to avoid continuous adjustment causing the clamping position to deviate cumulatively. After entering the bonding state, the coordination control module does not immediately allow the fastening module to move, but first performs pre-compensation; the pre-compensation displacement vector is jointly generated by the hole position deviation vector and the normalized force feedback vector, and is used to output a preset minimum attitude correction amount to compensate for local flexible deformation displacement when the hole position offset is less than the preset displacement threshold and the pressure force vector in a specific direction is greater than the preset force limit. In this embodiment, the hole position deviation vector used to generate the pre-compensation displacement vector is the triaxial hole position deviation vector after coordinate conversion. It is consistent with the normalized force feedback vector in terms of the number of components and the definition of the direction, and both correspond to the three directions of pitch adjustment axis, yaw adjustment axis and roll adjustment axis. The generation of the pre-compensation displacement vector follows the principle of coordinating the hole position correction trend with the force release trend: when the hole position deviation direction is consistent with the dominant force direction, the compensation amplitude in that direction is reduced first. When the hole position deviation is small but the force continues to increase, a small attitude correction is given first in the direction that is conducive to releasing local pressure; the force release direction is determined by the force change before and after the latest effective displacement of the corresponding attitude adjustment axis. The coordination control module records the direction of the most recent non-zero displacement command for the axis and the normalized force components before and after execution; if the normalized force component of the axis rises above the preset force fluctuation dead zone after execution, the opposite direction of the most recent command is determined as the force release direction. If the normalized force component of the axis decreases beyond the dead zone after execution, the direction of the most recent command will be determined as the direction that can be further corrected. If the force change is within the dead zone, the axis will not change direction according to the force change in this cycle; when a certain axis has no effective displacement history, a probing correction of no more than the minimum step size is first performed along the direction of decreasing hole position deviation, and only after the effective displacement flag is generated in this correction, the force release direction is determined in the next control cycle according to the above rules. If the probing correction does not generate a valid displacement indicator, the pre-compensation component of that axis remains zero; thus, the force release direction of each axis is determined by the correspondence between the executed displacement and the force change, rather than by the non-directional force value directly. Furthermore, the pre-compensated displacement vector is determined using a graded output method: when the hole position deviation is not greater than the first hole position threshold but greater than the second hole position threshold, and the stress index is lower than the second stress threshold, a medium compensation amount is output; when the hole position deviation is not greater than the second hole position threshold but the stress index is still rising, a small compensation amount is output. When the abnormal force flag is valid or the valid displacement flag corresponding to the most recent non-zero displacement of the axis to be executed is invalid, the pre-compensation component of the axis is recorded as zero and enters the stability check. In this embodiment, the pre-compensation displacement vector is configured as the execution correction amount output by the coordination control module in the fit state, driving the attitude axis to generate additional displacement; the attitude error vector is configured as a state parameter characterizing the deviation between the current adjustment position and the preset target attitude. In this embodiment, under the same workstation and the same workpiece model, the allowable stroke of a single axis is pre-calibrated into three discrete positions, where the minimum step size is less than the small compensation amount, the small compensation amount is less than the medium compensation amount, and the medium compensation amount is no greater than half of the corresponding allowable stroke of a single axis. The preferred method is to make the minimum step size correspond to the minimum non-zero displacement that can be stably distinguished by the position encoder. The small compensation amount is 1 to 3 times the minimum step size, and the medium compensation amount is 1 to 3 times the small compensation amount, so as to ensure that there is a fixed hierarchy between the probing correction, the fitting fine adjustment and the hole release, and that there is no continuous drift during the assembly process. This implementation is further limited to generation on a per-axis basis: first read the hole position deviation components and normalized force components corresponding to the pitch adjustment axis, yaw adjustment axis and roll adjustment axis. If the abnormal force indicator of a certain axis is valid, the valid displacement indicator corresponding to the most recent non-zero displacement of the axis is invalid, or the adjustment position of the axis has reached the maximum allowable travel boundary, then the pre-compensation component of the axis is directly recorded as zero. If the hole position deviation component of a certain axis is still between the first hole position threshold and the second hole position threshold, then the axis will be output with a moderate compensation amount and in the direction of decreasing hole position deviation. If the deviation component of a certain shaft hole position is no greater than the second hole position threshold and the normalized force component of the shaft continues to rise, then the shaft outputs with a small compensation amount and along the force release direction determined according to the aforementioned displacement and force change relationship. If the hole position correction direction of a certain axis is opposite to the force release direction, the axis will preferentially use a small compensation amount and output along the force release direction. At the same time, it is required that the hole position deviation after correction is still not greater than the second hole position threshold. Otherwise, the pre-compensation component of the axis is recorded as zero and the current position is kept for verification. After the pre-compensation components in the three directions are generated, they are then combined into a pre-compensation displacement vector, and the overall amplitude is limited by the maximum allowable stroke of the clamping mechanism. Furthermore, the pre-compensation components in the three directions are independently subjected to amplitude limiting calculations according to the single-axis allowable travel of the corresponding attitude adjustment axis before the synthesized displacement vector, and then the overall magnitude limiting is performed on the synthesized pre-compensation displacement vector. When a conflict arises between the single-axis limit and the overall modulus limit, the single-axis allowable stroke constraint takes priority; this maximum allowable stroke is jointly limited by the structural stroke of the clamping mechanism, the allowable deformation range of the workpiece, and the safety adjustment boundary of the attitude axis. After the attitude adjustment module performs pre-compensation displacement vector, the coordination control module enters the stability confirmation process. During this process, the system reacquires the visual detection results and force indicators, and re-determines whether the fastening conditions are met by combining the effective displacement flag output by the vibration judgment module. The effective displacement flag is used to confirm whether the most recent non-zero attitude adjustment command resulted in a directionally reliable movement, rather than requiring the clamping mechanism to move continuously throughout the entire stabilization confirmation time. Therefore, the vibration judgment module only updates the valid displacement flag according to the continuous set sampling period corresponding to the non-zero displacement command after the attitude adjustment module issues the non-zero displacement command; after the non-zero displacement is determined to be valid, the valid displacement flag is maintained until the next non-zero displacement command, the occurrence of an abnormal force flag, or the invalidity of the position encoder data. During the stability confirmation process, the zero displacement holding period does not change the valid displacement flag to invalid; if the next non-zero displacement does not reach the minimum valid displacement condition or the direction consistency condition, the valid displacement flag is immediately updated to invalid; this can both confirm that the pre-compensation action has been actually executed and avoid conflict with the valid displacement requirements in the fastening conditions due to remaining stationary during the stability confirmation stage. The state judgment module will switch the fit state to the fastening state only when the hole position deviation is not greater than the second hole position threshold, the contour stability is stable, the force index continuously reaches the second force threshold, and the effective displacement flag corresponding to the most recent non-zero attitude adjustment is valid and the visual effective flag is valid. The system requires switching to the fastened state when geometric alignment, edge stability, continuous contact, and the displacement confidence test conditions are met concurrently. Furthermore, in order to avoid extreme working conditions where the overall conditions are met but the local state is distorted, if a single point deviation in any hole area exceeds the second hole threshold, or if the normalized force feedback component corresponding to any attitude adjustment axis exceeds the abnormal judgment range, even if the overall force index does not exceed the limit, it will not enter the fastening state, but will remain in the fit state for further verification or switch to the abnormal retreat state. The review order within the stable confirmation time is further limited to: first freeze new large step adjustment commands, and only allow zero displacement or small compensation commands; Then continuously read the visual inspection results, force index and effective displacement mark; if visual invalidity, contour instability, abnormal force mark or newly executed non-zero displacement does not form effective displacement mark in any cycle during the stabilization confirmation time, then abandon the current fastening permission and maintain the fit state; the fastening module is allowed to operate only if the above conditions are still continuously met when the stabilization confirmation time ends. The vibration judgment module receives input data from the position change output by the position encoder; the direction consistency judgment refers to statistically analyzing the positive and negative directions of each position change within a continuously set sampling period. The minimum effective displacement threshold is derived from the displacement measurement accuracy. When the position change is less than the minimum effective displacement threshold, the system determines that the corresponding displacement signal is an invalid noise displacement originating from high-frequency mechanical vibration or gap hysteresis. The preset ratio is used to limit the percentage of sampling times in the same direction. Only when this percentage reaches the requirement can it be said that the position change in this period of time has a clear trend. The position change is determined based on the increment of each attitude adjustment axis in the current sampling period relative to the previous sampling period, so that the effective displacement flag corresponds to the actual motion trend after execution, rather than the absolute position itself; To avoid masking single-axis vibrations with only synthetic displacement, this embodiment preferably first performs directional consistency judgment on the pitch, yaw, and roll axes respectively, and then uses the validity of all axes involved in the current non-zero displacement command as the condition for the establishment of the overall valid displacement flag corresponding to the command; when the non-zero displacement command only involves one dominant axis, the validity of the dominant axis is used as the condition for the establishment of the overall valid displacement flag. Furthermore, when a zero-increment sample appears on a certain axis within a continuously set sampling period, if the absolute value of the zero-increment sample is not greater than the jitter interval corresponding to the displacement measurement accuracy, the sample is only treated as a non-directional sample, and is not counted in the number of samples with the same direction, nor is the opposite direction determination triggered separately. Only when the jitter exceeds the jitter range and a reverse increment occurs is it considered as directional inconsistency; this avoids the jitter samples with near-zero displacement from disrupting the directional consistency statistics. When the amplitude of the position change is not less than the minimum effective displacement threshold, and the proportion of sampling times in the same direction reaches a preset ratio, the vibration judgment module generates an effective displacement flag; otherwise, it is invalid. When the valid displacement flag generated for a non-zero displacement command is invalid, the coordination control module prohibits the attitude adjustment module from performing attitude adjustment with a displacement greater than the preset step size, so as to prevent the machine from continuing to give a large correction amount when it is not stable. If the valid displacement flag corresponding to multiple consecutive non-zero displacement commands is invalid and the force index increases, it indicates that there may be a situation of vibration superposition and contact growth at the current assembly point. The coordination control module will switch the attitude adjustment speed to the preset low speed level and switch the stabilization confirmation time to the preset extended value. The preset step size is preferably a small compensation amount or a gear value no greater than the small compensation amount. The preset low speed gear corresponds to the adjustment speed used by the small step size. The preset extension value is to add at least one stable confirmation cycle to the original stable confirmation time, but not more than twice the original stable confirmation time. This way, when the mechanical vibration has not yet subsided, the system can only perform minor corrections that can be stably identified by the position encoder, and the verification and observation time is extended accordingly. In this implementation method, the force detection module extracts not a single driving quantity, but a normalized force feedback vector and force index formed by the same set of axial force components. The state judgment module does not switch to an abstract control mode, but rather to the assembly stage that directly corresponds to the degree of fit of the workpiece, the degree of hole alignment, and the authenticity of the displacement; the output of the pre-compensated displacement vector is not a fixed correction, but a fine-tuning result of attitude obtained under the combined action of three-axis hole position deviation, traceable force release direction, and force state; this can reduce misjudgments that the visual alignment is complete but the workpiece is not yet properly fitted, or that the force has increased but the displacement is not real.

[0020] In a preferred embodiment, the fastening module further includes a fastening driver, a torque detection unit, and an angle detection unit; the fastening module performs fastening in stages: a low-speed contact section, a pre-tightening section, a stability confirmation section, and a final fastening section. In the low-speed contact section, the tightening actuator runs at the first speed until the tightening torque reaches the contact threshold; in the pre-tightening section, it runs at the second speed until the tightening torque reaches the pre-tightening threshold; in the stabilization confirmation section, the tightening torque is kept stable for a preset time; in the final tightening section, it runs until the tightening angle reaches the target tightening angle. After each tightening stage is completed, the current stage tightening torque and tightening angle obtained by the torque detection unit and angle detection unit are sent to the coordination control module. When the clamping torque is greater than or equal to the current stage preset torque limit, or when the clamping torque and clamping angle deviate from the preset torque range and preset angle range, the coordination control module stops clamping, controls the attitude adjustment module to reduce clamping constraints, and switches to abnormal retreat state. In the coarse positioning state, the coordination control module sends a global sampling command to the vision detection module and prohibits the fastening module from moving. In the fitting state, it sends a local area sampling command to the vision detection module. In the fastening state, it maintains the target position of the attitude adjustment module and makes the attitude adjustment module perform preset damping holding control. When a visually valid marker becomes invalid for more than a preset number of cycles, the coordination control module pauses the attitude adjustment module's action and re-triggers the visual detection module. When the preset visual recovery time limit is exceeded, it switches to the abnormal rollback state. When the fastening is completed and the hole position deviation, stress index, adjustment position and fastening torque are all within the corresponding preset threshold range, the coordination control module sends an assembly qualified signal to the host computer and stores the assembly data.

[0021] This implementation describes the action arrangement after entering the fastening state, as well as the sampling and anomaly handling logic in each state; the coordination control module sends a global sampling command to the vision inspection module in the coarse positioning state. At this time, the industrial camera's acquisition range covers the hole position area and a larger observation area related to the installation edge, so as to maintain the effective recognition state of the target area when the hole position deviation is greater than the preset global field of view offset limit. In this state, the coordination control module simultaneously prohibits the fastening module from operating, to prevent premature tightening before the workpiece has reached the fitting condition; After the state judgment module switches the assembly state to the mating state, the coordination control module sends a local area sampling command to the vision inspection module. Local area sampling means concentrating image acquisition and processing on the vicinity of the hole and the edge mating area to improve the recognition stability during the close-range centering stage. At this time, the attitude adjustment module can still perform small step corrections under the control of the coordination control module, but the fastening module continues to standby until the status judgment module confirms that the fastening conditions are met. After entering the fastening state, the coordination control module maintains the target position of the attitude adjustment module unchanged and makes it perform preset damping holding control; Damping holding control freezes the active position correction command output of the attitude adjustment module, triggering the driver to output a limited damping torque to the current position, thereby enabling the clamping mechanism to maintain a predetermined attitude during the clamping process and reducing the swing caused by the clamping reaction force. This logic is used to suppress attitude axis servo oscillation, secondary hole position deviation, and sudden changes in edge force caused by the reaction force applied by the tightening actuator during the tightening process; Maintaining the target position unchanged refers to the attitude target parameters after the freeze system enters a tightened state and is stabilized and confirmed. The fastening module includes a tightening actuator, a fastening driver, a torque detection unit, and an angle detection unit; the torque detection unit is used to obtain the current fastening torque, and the angle detection unit is used to obtain the current fastening angle; the fastening process is executed sequentially in the form of a low-speed contact section, a pre-tightening section, a stabilization confirmation section, and a final fastening section; The rotations at each stage are not simply continuous. Instead, each stage returns torque and angle data to the coordination control module after completion. The coordination control module then determines whether to continue based on the current assembly status. In the low-speed contact section, the tightening actuator operates at the first speed until the tightening torque reaches the contact threshold; the contact threshold indicates that the fastener has established initial contact with the mounting hole or thread, but has not yet entered the stage of large clamping force growth. The first rotational speed is configured as the first preset low speed gear, which is set to limit mechanical impact deformation and fastener misalignment interference in the initial contact stage. Once the contact threshold is reached, the fastening module enters the pre-tightening section and runs at a second speed until the fastening torque reaches the pre-tightening threshold. The second speed can be higher than the first speed, but is still constrained by the process allowable range. The pre-tightening threshold indicates that the fastener has applied an initial clamping force to the mudguard and the mounting component. At this point, the material near the edge of the mudguard and the holes begins to redistribute stress according to the installation state. If the first derivative of the torque at this stage is greater than the preset growth rate limit or the torque-angle curve exceeds the preset boundary window, an interference alarm will be triggered and the final fastening section execution command will be cut off. During the stabilization confirmation phase, the fastening module maintains the fastening torque stable for a preset time; the action configuration is set to freeze the current stage rotational output and maintain the stage fastening state, triggering the coordination control module to verify the force data, contour fitting parameters and attitude feedback status; The purpose of setting this stage is to incorporate the material springback and fixture response after initial clamping into the judgment, so as to avoid directly entering the final tightening before the structure is stable; The preset time is defined according to the system cycle and determined by the fastening process verification results. Its value is based on the principle of being able to observe the torque stabilization trend without significantly increasing the cycle load. In the final tightening stage, the tightening actuator continues to operate until the tightening angle reaches the target tightening angle; the target tightening angle and the pre-tightening threshold together limit the final locking amount to ensure that the fastener reaches the required clamping state; The final tightening section uses the angle increment as the control parameter for the tightening depth; while the torque detection unit continues to perform process monitoring to prevent abnormal over-limits. After each tightening stage is completed, the tightening module sends the tightening torque and tightening angle of the current stage to the coordination control module. The coordination control module compares these values ​​with the preset torque range and preset angle range corresponding to the current stage. If the tightening torque is greater than the preset torque upper limit of the current stage, it is determined that the tightening system has encountered excessive resistance. If the clamping torque and clamping angle deviate from the preset range, it indicates that the clamping path is inconsistent with the process window. At this time, the coordination control module immediately stops clamping, controls the attitude adjustment module to reduce the clamping constraint, and switches to the abnormal retraction state. To reduce clamping constraints, under the constraint that the fluctuation range of the current position is limited to the preset tolerance range, the multi-axis drive motor is switched to a low stiffness compliant or micro-floating mode to release assembly interference stress, suppress local reverse forces on the workpiece, and retain the initial positioning point of the workpiece. The current stage preset torque upper limit, preset torque range and preset angle range are set independently for the low speed contact section, pre-tightening section, stability confirmation section and final tightening section, respectively, to avoid reducing the clarity of judgment by covering different tightening stages with a single limit value at the same time. Furthermore, the preset torque range and preset angle range for each stage are determined by qualified assembly process data under the same workstation and the same workpiece model. The low-speed contact section uses the torque rise range near the contact threshold as the torque range, the pre-tightening section uses the torque range near the pre-tightening threshold and the corresponding cumulative angle range as the preset window, the stabilization confirmation section uses the upper limit of the torque fluctuation during the holding period as the upper limit of the range, and the final tightening section uses the allowable angle deviation range near the target tightening angle and the corresponding termination torque range as the range. When the workpiece model, fastener specifications, or installation materials are changed, a set of stage range parameters pre-stored at the corresponding workstation are called up, and the switching is not performed in real time during the same assembly process. The visual anomaly handling and tightening process work together; when the visual valid markers are continuously invalid for a preset number of cycles, the coordination control module pauses the posture adjustment module's action and re-triggers the visual detection module; the above logic is used to isolate signal loss and continuous visual feature loss faults caused by short-term environmental interference. If the visual validity flag becomes valid again after being retried, the system continues to judge the current stage; if it still fails to recover after exceeding the preset visual recovery time limit, the coordination control module switches to the abnormal rollback state; the preset number of cycles and the visual recovery time limit are both set according to the system cycle, and the values ​​are determined together based on the visual sampling frequency, occlusion duration characteristics and workstation cycle time. In this embodiment, the upper limit of the preset visual recovery time is implemented according to the number of control cycles and is greater than the preset number of cycles; when the visual valid flag is continuously invalid for a preset number of cycles but has not exceeded the upper limit of the visual recovery time, only visual detection is allowed to be retried and the current position is maintained, and large stride posture adjustment is not restored. When performing the assembly completion judgment, the coordination control module synchronously performs the verification of the fastening module completion signal, and verifies whether the hole position deviation, force index, adjustment position and fastening torque all meet the corresponding preset tolerance threshold range conditions; the hole position deviation is used to confirm that the final hole position has not shifted again during the fastening process; The stress index is used to confirm that no abnormal residual stress has formed near the edges and holes; the adjustment position is used to confirm that the attitude axis is still within the allowable holding range; the tightening torque is used to confirm that the tightening force falls within the process window. Only when all the above conditions are met will the coordination and control module send an assembly qualification signal to the host computer and store the assembly data for this assembly. The stored data includes visual inspection results, force detection results, posture adjustment position and fastening process data, which facilitates subsequent traceability of the assembly process and process verification. This embodiment is applicable in engineering to workpieces such as mudguards, which have easily deformable edges, scattered holes, and whose visual area may be obstructed during the fastening process. By organizing global sampling, local region sampling, posture maintenance, segmented clamping, and anomaly backoff in sequence, a clear sequential relationship can be established between visual information, posture maintenance, and clamping actions. As the fasteners are engaged, pre-tightened, stabilized, and finally locked, the system can promptly detect problems such as abnormal torque, angular deviation, visual failure, and unstable posture. When an abnormality occurs, the system will stop tightening, thereby reducing the risk of assembly misalignment and workpiece damage.

Claims

1. A multi-angle adjustment and assembly system for mudguards integrating machine vision, used for multi-angle adjustment and assembly of workpieces to be assembled, the workpieces including mudguards, characterized in that, include: The visual inspection module is used to acquire images of the hole area and edge mating area of ​​the workpiece to be assembled, generate visually valid marks based on the clarity and integrity of the images, and output visual inspection results of hole deviation and contour stability. The attitude adjustment module includes a multi-axis drive motor, a clamping mechanism, and a position encoder. The multi-axis drive motor is used to drive the clamping mechanism to adjust the attitude of the workpiece to be assembled, and the position encoder is used to output the position change. The force detection module is connected to the multi-axis drive motor, obtains the motor current, estimated torque and following error of the multi-axis drive motor, and obtains the force index and force change rate based on the normalized motor current, estimated torque and following error; The vibration judgment module generates an effective displacement flag when the amplitude of the position change reaches the minimum effective displacement threshold corresponding to the preset displacement measurement accuracy and the direction is consistent within a continuously set sampling period. The status judgment module is used to switch the assembly status between coarse positioning, fitting, fastening and abnormal retreat states according to preset status switching conditions based on hole position deviation, contour stability, stress index, effective displacement mark and visual effective mark. The fastening module includes a tightening actuator for performing fastening when the assembly state is switched to the fastening state; The coordination and control module is communicatively connected to the vision detection module, the posture adjustment module, the force detection module, the vibration judgment module, the state judgment module, and the fastening module, respectively, and sends control commands to the posture adjustment module and the fastening module according to the assembly state.

2. The multi-angle adjustment assembly system for mudguards integrating machine vision according to claim 1, characterized in that, The visual inspection module includes an industrial camera, a light source, a trigger controller, and an image processing unit; The industrial camera acquires the image under the control of the trigger controller; The image processing unit is used to generate the visually valid mark when the image sharpness reaches a preset sharpness threshold and the image integrity reaches a preset integrity threshold. The image processing unit extracts the center coordinates of the hole and the center coordinates of the target installation center based on the image and calculates the hole deviation. The image processing unit is used to determine the stability of the contour based on the edge fitting error within a continuous sampling period, and to determine the contour stability as stable when the edge fitting error is less than a preset fitting threshold, and to determine the contour stability as unstable when the edge fitting error is greater than or equal to the preset fitting threshold, and to send the hole position deviation, the contour stability, and the visually valid mark to the coordination control module.

3. The multi-angle adjustment assembly system for mudguards integrating machine vision according to claim 1, characterized in that, The multi-axis drive motor includes a pitch adjustment axis, a yaw adjustment axis and a roll adjustment axis, and the attitude adjustment module also includes a servo driver, which outputs the following error. The position encoder sends the adjusted position to the coordination control module, and the attitude error vector is obtained by comparing the preset target attitude with the adjusted position. The coordination control module converts the orifice position deviation into an orifice position deviation vector, constructs the normalized force components corresponding to the pitch adjustment axis, yaw adjustment axis and yaw adjustment axis into a normalized force feedback vector, and controls the attitude adjustment module to perform attitude adjustment based on the orifice position deviation vector, the attitude error vector and the normalized force feedback vector.

4. The multi-angle adjustment assembly system for mudguards integrating machine vision according to claim 1, characterized in that, The force detection module performs zero-point compensation and low-pass filtering on the acquired motor current, estimated torque, and following error, and normalizes the motor current, estimated torque, and following error. The normalized motor current, the estimated torque, and the following error are weighted and summed according to a preset fixed weighting coefficient to obtain the force index, and the sum of the preset fixed weighting coefficients is 1. The force detection module calculates the force change rate based on the force index of adjacent sampling periods, and sends an abnormal force flag to the coordination control module when the force index is greater than or equal to a preset force threshold or the force change rate is greater than or equal to a preset change rate threshold.

5. The multi-angle adjustment assembly system for mudguards integrating machine vision according to claim 2, characterized in that, The preset state switching conditions of the state determination module include: When the hole position deviation is not greater than the preset first hole position threshold and the force index reaches the preset first force threshold within a continuously set number of control cycles, the state judgment module switches the coarse positioning state to the fitting state. When the hole position deviation is not greater than the preset second hole position threshold, the contour stability is stable, the force index continuously reaches the preset second force threshold, the effective displacement mark is valid and the visual effective mark is valid, the fastening condition is determined to be met, and the state judgment module switches the fitting state to the fastening state. The first hole position threshold is greater than the second hole position threshold; the first force threshold is less than the second force threshold; if the hole position deviation continues to be greater than the first hole position threshold for more than a preset time, the state judgment module switches to the abnormal retreat state, and the coordination control module controls the attitude adjustment module to retreat to the initial position.

6. The multi-angle adjustment assembly system for mudguards integrating machine vision according to claim 5, characterized in that, In the fitting state, the coordination control module generates a pre-compensation displacement vector based on the hole position deviation vector obtained by converting the hole position deviation and the normalized force components obtained by converting the force index corresponding to each adjustment shaft of the multi-axis drive motor. The coordination control module limits the magnitude of the pre-compensated displacement vector to no greater than the preset maximum allowable stroke of the clamping mechanism; After the attitude adjustment module executes the pre-compensation displacement vector, the coordination control module reacquires the visual detection results and the force index within the set stability confirmation time, and allows the fastening module to operate when the fastening conditions are met.

7. The multi-angle adjustment assembly system for mudguards integrating machine vision according to claim 1, characterized in that, The vibration judgment module performs directional consistency judgment on the position change within a continuously set sampling period. When the amplitude of the position change is not less than the minimum effective displacement threshold corresponding to the preset displacement measurement accuracy, and the proportion of sampling times with the same position change direction within a continuously set sampling period reaches a preset ratio, the effective displacement flag is determined to be valid; otherwise, the effective displacement flag is determined to be invalid. When the effective displacement flag is invalid, the coordination control module prohibits the attitude adjustment module from performing attitude adjustment with a displacement greater than a preset step size. When the effective displacement flag is continuously invalid and the force index increases, the attitude adjustment speed is switched to a preset low speed and the stabilization confirmation time is switched to a preset extended value.

8. The multi-angle adjustment assembly system for mudguards integrating machine vision according to claim 5, characterized in that, The fastening module also includes a fastening driver, a torque detection unit, and an angle detection unit; the fastening module performs fastening according to a low-speed contact section, a pre-tightening section, a stability confirmation section, and a final fastening section. In the low-speed contact section, the tightening actuator operates at a first speed until the tightening torque reaches the contact threshold; in the pre-tightening section, it operates at a second speed until the tightening torque reaches the pre-tightening threshold; in the stabilization confirmation section, the tightening torque is kept stable for a preset time. In the final tightening section, the operation continues until the tightening angle reaches the target tightening angle; After each tightening stage is completed, the current stage tightening torque and tightening angle obtained by the torque detection unit and the angle detection unit are sent to the coordination control module. When the clamping torque is greater than or equal to the current stage preset torque limit, or when the clamping torque and clamping angle deviate from the preset torque range and preset angle range, the coordination control module stops clamping, controls the attitude adjustment module to reduce clamping constraints, and switches to the abnormal retreat state.

9. The multi-angle adjustment assembly system for mudguards integrating machine vision according to claim 3, characterized in that, The coordination control module sends a global sampling command to the vision detection module and prohibits the fastening module from moving in the coarse positioning state; sends a local area sampling command to the vision detection module in the fitting state; and maintains the target position of the posture adjustment module unchanged and makes the posture adjustment module perform preset damping holding control in the fastening state. When the visual valid marker is invalid for more than a preset number of consecutive cycles, the coordination control module pauses the action of the posture adjustment module and re-triggers the visual detection module. When the preset visual recovery time limit is exceeded, it switches to the abnormal rollback state. When fastening is completed and the hole position deviation, force index, adjustment position and fastening torque are all within the corresponding preset threshold range, the coordination control module sends an assembly qualified signal to the host computer and stores the assembly data.

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