A numerical control lathe sling position control method and system based on distributed control

Abstract

This invention discloses a CNC lathe lifting fixture position control method and system based on distributed control, relating to the field of automatic loading control technology for CNC lathes. The method includes the following steps: receiving the CNC lathe loading task and generating lifting status data; establishing a distributed control relationship and triggering the end control process; determining the equivalent control point of the workpiece to be clamped end and generating initial clamping deviation; estimating the workpiece to be clamped end pose and estimation reliability using the tension compensation SR-UKF algorithm; generating chuck entry conditions and decomposing them into local constraints; calculating the correction amount of each distributed control node using the chuck constraint DMPC algorithm and generating control markers; performing minor corrections, low-speed feeding, or safe return, and updating algorithm parameters and local constraints after chuck clamping. This invention improves the centering accuracy, collaborative control stability, and clamping safety during the workpiece entering the chuck.

Description

Technical Field

[0001] This invention relates to the field of automatic feeding control technology for CNC lathes, and in particular to a method and system for controlling the position of a CNC lathe lifting device based on distributed control. Background Technology

[0002] With the increasing demand for automated loading of CNC lathes and unmanned machining in workshops, the technology for lifting tool feeding and chuck clamping control for long shaft and cylindrical workpieces has attracted attention. Existing CNC machine tool loading and unloading solutions mainly revolve around feed angle calculation, obstacle avoidance path planning inside the machine tool, and chuck release and clamping coordination. For example, CN109894633B has disclosed a flexible loading and unloading method for CNC machine tools using a gantry robot. In the field of lifting tool control, there are also anti-sway control solutions based on trajectory planning or nonlinear models, such as CN114955856A and CN109896423B.

[0003] However, in actual hoisting and loading processes, the positioning of the lifting device's center point does not necessarily mean that the workpiece's clamping end is aligned with the chuck's centerline. Especially in scenarios with uneven sling tension, workpiece end sagging, and limited chuck inlet space, lateral deviations, height deviations, pitch angle deviations, and yaw angle deviations of the workpiece's clamping end are prone to occur, leading to low-speed feeding jamming, chuck jaw collisions, or coaxiality errors after clamping. Existing technologies typically do not treat the equivalent control point of the workpiece's clamping end as a common control object for each distributed control node. They also lack processing for estimating the workpiece's clamping end's pose and estimation reliability in the critical feeding section at the chuck inlet, combined with the tension state. Furthermore, they do not incorporate the chuck loading conditions into the predicted state, objective function, and axial feeding limits, nor do they use the clamping verification results to back-update the estimated parameters, control weights, and local constraints.

[0004] Therefore, how to provide a CNC lathe lifting position control method and system based on distributed control is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] One objective of this invention is to propose a CNC lathe lifting fixture position control method and system based on distributed control. This invention fully utilizes tension-compensated SR-UKF pose estimation, chuck-constrained DMPC collaborative control, and clamping verification closed-loop update technology. It uses the equivalent control point of the workpiece to be clamped end to replace the lifting fixture center point as the feeding control object, realizing the collaborative perception, centering correction, low-speed feeding, and safe return of the lifting fixture state, workpiece end state, and chuck state. It has the advantages of high clamping positioning accuracy, high feeding process safety, distributed collaborative stability, and adaptive parameter update.

[0006] A CNC lathe lifting device position control method based on distributed control according to an embodiment of the present invention includes the following steps: Step 1: Receive the loading task from the CNC lathe, collect the status of the lifting device, the status of the workpiece to be clamped end, and the status of the chuck, and generate lifting status data; Step 2: Establish distributed control relationships based on each distributed control node, and trigger the end control process when the workpiece enters the critical feeding section of the chuck inlet at the clamping end; Step 3: Determine the equivalent control point of the workpiece to be clamped end based on the workpiece parameters, lifting point position and clamping position of the lifting device, and generate the initial clamping deviation relative to the chuck center line; Step 4: Input the hoisting status data into the tension compensation SR-UKF algorithm to estimate the workpiece's clamping end pose and estimation reliability; Step 5: Generate chuck loading conditions based on chuck status and lathe internal safety clearance, and decompose chuck loading conditions into local constraints of each distributed control node; Step 6: Input the workpiece's clamping end pose, estimated confidence level, and local constraints into the DMPC algorithm for chuck constraints, calculate the correction amount for each distributed control node, and generate a send-in permission flag, a pause waiting flag, or a safe return flag. Step 7: Perform minor correction, low-speed feeding, or safe return according to the correction amount and mark. After the chuck is clamped, generate the clamping verification result and update the tension compensation SR-UKF algorithm parameters, chuck mouth constraint DMPC algorithm parameters, and local constraints of the distributed control node based on the clamping verification result.

[0007] Optionally, step one specifically includes: The system receives loading tasks from a CNC lathe, acquires workpiece parameters, lifting point positions, lifting fixture clamping positions, and lathe calibration data. The workpiece parameters include workpiece diameter, workpiece length, and workpiece weight. The lathe calibration data includes the transformation matrix between the lathe coordinate system and the lifting fixture coordinate system, the chuck centerline position, and the chuck inlet plane position. The status of the lifting device, the status of the workpiece to be clamped end, and the status of the chuck are collected. The status of the lifting device includes the traveling position, traveling speed, lateral position, lateral speed, lifting height, lifting speed, hook load, lifting device attitude angle, and sling tension. The state of the workpiece to be clamped end includes the distance measurement value of the workpiece to be clamped end and the distance measurement reliability mark; The chuck status includes chuck opening degree, chuck position feedback, chuck clamping permission status, spindle center line calibration status, protective door interlock status, tailstock avoidance status, emergency stop status, and safe return zone status. A unified sampling time stamp is written to the status of the lifting device, the status of the workpiece to be clamped end, and the status of the chuck. When the sampling time stamp deviation exceeds the preset synchronization threshold, a low confidence flag is written. When the collected data exceeds the mechanism travel limit, the change in adjacent sampling cycles exceeds the preset change threshold, or there is a conflict with the chuck status, write an abnormal data flag. Using the transformation matrix between the lathe coordinate system and the lifting fixture coordinate system, the lifting fixture state, the workpiece clamping end state, and the chuck state are transformed to the lathe coordinate system to obtain the coordinate transformation result; The lifting status data is obtained by combining the CNC lathe loading task, workpiece parameters, lifting point position, lifting fixture clamping position, lathe calibration data, lifting fixture status, workpiece clamping end status, chuck status, coordinate transformation results, low confidence markers, and abnormal data markers.

[0008] Optionally, step two specifically includes: The traveling trolley control node is associated with axial feed control, the lateral movement control node is associated with lateral centering control, the lifting control node is associated with height compensation control, the spreader attitude fine-tuning control node is associated with attitude correction control, the chuck linkage control node is associated with feed permission control, and the safety interlock control node is associated with pause and retraction control, thus obtaining a distributed control relationship. The axial distance between the workpiece's clamping end and the chuck inlet is calculated using the coordinate transformation results; The preset critical distance is taken as the larger of 1.5 times the workpiece diameter, the sum of the length to be clamped, the low-speed braking distance, the control response distance, and the chuck mouth safety margin. When the axial distance is less than the preset critical distance, and the chuck opening is not less than the sum of the workpiece diameter and the chuck inlet loading gap, the chuck position feedback is in the open state, the chuck clamping permission state is valid, the protective door interlock state is valid, the tailstock avoidance state is valid, the emergency stop state is not triggered, and the safe return area state is reachable, the chuck inlet critical feed section mark is set to valid. When the critical feed section mark at the chuck inlet is valid, the use of the spreader center point position as the feed judgment criterion is stopped, and the end control process is triggered.

[0009] Optionally, step three specifically includes: Determine the end of the workpiece to be entered into the chuck according to the clamping direction and the marking of the end to be clamped, and determine the center of the end face of that end as the equivalent control point of the end to be clamped. The position of the equivalent control point of the workpiece to be clamped end in the coordinate system is corrected by using the position of the lifting point, the clamping position of the lifting device, and the attitude angle of the lifting device. The end face position is corrected by using the distance measurement value of the workpiece to be clamped end to perform end face correction; Using the transformation matrix between the lathe coordinate system and the lifting fixture coordinate system, the equivalent control points of the workpiece to be clamped end are transformed to the lathe coordinate system; Calculate the lateral deviation, height deviation, and axial distance of the equivalent control point of the workpiece to be clamped relative to the chuck centerline, and calculate the pitch angle deviation and yaw angle deviation between the workpiece axis and the chuck centerline; The lateral deviation, height deviation, axial distance, pitch angle deviation, yaw angle deviation, and end face correction are combined to form the initial mounting deviation; When the end face correction exceeds the preset end face correction threshold, or any deviation in the initial mounting deviation exceeds the allowable range of the critical feed section at the chuck inlet, a low confidence flag is written to the initial mounting deviation.

[0010] Optionally, step four specifically includes: The state vector of the tension-compensated SR-UKF algorithm includes lateral deviation, altitude deviation, axial distance, pitch deviation, yaw deviation, end droop correction, lateral deviation change, altitude deviation change, and attitude deviation change. The proportion of lateral tension difference is obtained by subtracting the tension of the left sling from the tension of the right sling and dividing by the average tension of the slings. The proportion of longitudinal tension difference is obtained by subtracting the tension of the rear sling from the tension of the front sling and dividing by the average tension of the slings. The proportion of load change is obtained by subtracting the hook load of the previous sampling period from the current hook load and dividing by the hook load of the previous sampling period. The lateral tension compensation amount is obtained by multiplying the lateral tension difference ratio by the preset lateral compensation coefficient; the height tension compensation amount is obtained by multiplying the longitudinal tension difference ratio by the preset height compensation coefficient; the yaw angle tension compensation amount is obtained by multiplying the lateral tension difference ratio by the preset yaw compensation coefficient; the pitch angle tension compensation amount is obtained by multiplying the longitudinal tension difference ratio by the preset pitch compensation coefficient; and the end droop compensation amount is obtained by multiplying the load change ratio by the preset droop compensation coefficient. By incorporating each tension compensation amount into the SR-UKF state prediction rule, the predicted pose of the workpiece's clamping end is obtained. The process noise covariance matrix is ​​corrected according to the proportion of tension difference and load change, and the predicted covariance square root factor is obtained through QR decomposition and Cholesky rank-one update.

[0011] Optionally, the tension compensation SR-UKF algorithm specifically includes: The distance measurement value of the workpiece to be clamped end, the end face correction amount, and the lateral deviation and height deviation in the initial clamping deviation are combined into the actual measurement vector. The predicted pose of the workpiece to be clamped end is mapped to a predicted measurement vector, and the information is obtained by subtracting the predicted measurement vector from the actual measurement vector. When the abnormal data is marked as valid, the ranging confidence mark is marked as low confidence, or the low confidence mark is valid, the measurement noise of the corresponding measurement item is taken as four times the reference measurement noise. When the direction of the innovation is consistent with the direction of the corresponding tension compensation, the tension compensation retention coefficient is one; when the direction of the innovation is opposite to the direction of the corresponding tension compensation, the tension compensation retention coefficient is half; when two consecutive sampling periods in the same direction are opposite, the tension compensation retention coefficient is zero. The tension compensation amount in the corresponding direction is corrected according to the tension compensation retention coefficient, and the predicted state in the corresponding direction is recalculated with the corrected tension compensation amount. The Kalman gain is calculated based on the square root factor of the prediction covariance, the measurement noise covariance, and the innovation. The prediction state vector is then corrected based on the Kalman gain and the innovation to obtain the workpiece's pose at the clamping end. The confidence level is estimated by subtracting the innovation deduction item, tension compensation deduction item, measurement noise deduction item, and low confidence mark deduction item from the full confidence value; the innovation deduction item is obtained by dividing the absolute value of the innovation by the allowable deviation in the corresponding direction, and the tension compensation deduction item is obtained by dividing the absolute value of the tension compensation by the allowable compensation in the corresponding direction.

[0012] Optionally, step five specifically includes: The lower limit of the chuck opening is obtained by adding the workpiece diameter to the chuck opening clearance. When the chuck opening reaches the lower limit and the jaw position feedback is in the open state, the radial allowable setting of the chuck opening is valid. When the chuck clamping permission is valid, the protective door interlock is permitted, the tailstock avoidance is valid, the emergency stop is not triggered, and the safe retreat area is reachable, the chuck port interlock permission is set to valid. When the current values ​​of the internal safety clearances of the lathe are not less than the corresponding configured values, the safety clearance permission is set to valid; When the chuck radial clearance, chuck interlock clearance, and safety clearance clearance are all valid, the chuck loading condition is set to valid. The chuck loading conditions are broken down into axial feeding constraints, centering boundary constraints, attitude boundary constraints, chuck motion constraints, and stop / retract constraints, which serve as local constraints for each distributed control node.

[0013] Optionally, step six specifically includes: Configure the confidence threshold, confidence correction coefficient, consistency threshold, axial speed limit, and reverse backoff amount limit for the DMPC algorithm with caliper port constraint. The local constraints are converted into chuck constraint residuals, which include lateral centering residuals, height centering residuals, axial entry residuals, pitch angle residuals, yaw angle residuals, and safety clearance residuals. Lateral deviation, altitude deviation, axial distance, pitch angle, yaw angle, and chuck constraint residuals are used as the DMPC prediction states; When the residual constraint of each chuck port is not less than zero and the chuck action constraint is effective, the chuck port loading control value is set to one; otherwise, it is set to zero. At each prediction time, the chuck constraint residual and chuck loading control value are recalculated, and the chuck constraint residual is written into the chuck constraint out-of-bounds cost of the DMPC objective function; The DMPC objective function includes deviation cost, correction cost, card constraint out-of-bounds cost, input prohibition cost, and distributed consistency cost. When the chuck inlet loading control value is set to 1, the axial feed correction value ranges from zero to the upper limit of the axial speed; when the chuck inlet loading control value is zero and the safety clearance residual is not less than zero, the axial feed correction value is zero; when the safety clearance residual is less than zero, the axial feed correction value ranges from the upper limit of the reverse return amount to zero. When the estimated confidence level is lower than the confidence level threshold, the axial correction is set to zero, and the upper limits of the lateral correction, altitude correction, pitch correction, and yaw correction are multiplied by the confidence level correction coefficient, respectively. Each distributed control node solves a local quadratic programming problem and exchanges the chuck constraint residuals, the predicted pose of the workpiece to be clamped end, and the chuck loading control values. When all predicted chuck loading entry control values ​​are set to one and the consistency difference does not exceed the consistency threshold, an input permission flag is output; when the chuck loading entry control value is zero, the safety clearance residual is not less than zero, and there are non-zero lateral corrections, altitude corrections, pitch corrections, or yaw corrections, a pause waiting flag is output; when the safety clearance residual is less than zero or the safety return permission in the stop-and-go constraint is valid, a safety return flag is output.

[0014] Optionally, step seven specifically includes: When the safety return flag is valid, perform a minor correction corresponding to the safety return direction; When the pause-wait marker is valid and the safe return marker is invalid, the axial feed correction is set to zero, and the lateral, altitude, pitch, and yaw corrections are executed. When the feed permission mark is valid, perform low-speed feed according to the axial feed correction amount, and simultaneously perform lateral correction, altitude correction, pitch correction and yaw correction. After the chuck is clamped, the position of the workpiece to be clamped is recalculated based on the distance value of the workpiece to be clamped end, the feedback of the jaw position, and the position of the chuck center line. The clamping end of the workpiece is re-measured and compared with the position of the clamping end of the workpiece before clamping to obtain the clamping verification residual. The clamping verification residual includes lateral residual, height residual, axial residual, pitch angle residual and yaw angle residual. The loading and checking results are generated based on the loading and checking residuals and the feedback of the jaw positions. Tension compensation coefficients and measurement noise parameters based on the SR-UKF algorithm for tension compensation based on mounting verification residual correction; Based on whether the residual of the card loading verification exceeds the allowable deviation in the corresponding direction, the card opening constraint penalty weight and the input prohibition penalty weight of the DMPC algorithm are modified. Record the direction, value, and whether the upper limit of the correction amount is reached for each correction, forming a continuous record of corrections exceeding the limit in the same direction; Based on continuous same-direction correction of out-of-limit records, the local constraints of the corresponding distributed control nodes are corrected.

[0015] A CNC lathe lifting fixture position control system based on distributed control according to an embodiment of the present invention includes the following modules: The status generation module is used to receive loading tasks from CNC lathes, collect the status of lifting fixtures, the status of the workpiece to be clamped end and the status of chuck, and generate lifting status data. The process triggering module is used to establish a distributed control relationship based on each distributed control node, and to trigger the end control process when the workpiece waiting to be clamped enters the critical feeding section of the chuck inlet. The deviation generation module is used to determine the equivalent control point of the workpiece to be clamped end based on workpiece parameters, lifting point position and lifting fixture clamping position, and generate the initial clamping deviation relative to the chuck centerline. The tension estimation module is used to input the hoisting status data into the tension compensation SR-UKF algorithm to estimate the workpiece's clamping end pose and estimation reliability; The condition decomposition module is used to generate chuck loading conditions based on the chuck status and the internal safety clearance of the lathe, and decompose the chuck loading conditions into local constraints of each distributed control node. The collaborative control module is used to input the workpiece's clamping end pose, estimated confidence level, and local constraints into the DMPC algorithm for chuck constraints, calculate the correction amount for each distributed control node, and generate a send-in permission flag, a pause waiting flag, or a safe return flag. The verification and update module is used to perform minor corrections, slow feeding, or safe return based on the correction amount and markings. After the chuck is clamped, it generates a clamping verification result and updates the tension compensation SR-UKF algorithm parameters, chuck mouth constraint DMPC algorithm parameters, and local constraints of the distributed control nodes based on the clamping verification result.

[0016] The beneficial effects of this invention are: This invention solves the problem of traditional lifting devices failing to align with the chuck centerline when the workpiece's clamping end enters the critical feeding section of the chuck inlet. It triggers the end control process by using the equivalent control point of the workpiece's clamping end instead of the lifting device's center point as the control object. This feature enables the trolley control node, lateral movement control node, lifting control node, and lifting device attitude fine-tuning control node to perform corrections around the same end target. It can simultaneously constrain lateral deviation, height deviation, axial distance, pitch angle deviation, and yaw angle deviation before feeding, reducing jamming, rubbing, and end-point misalignment at the chuck inlet. This invention inputs lifting status data into the tension compensation SR-UKF algorithm. By incorporating the proportion of sling tension difference, the proportion of hook load change, and the end sag compensation amount into status prediction and measurement updates, it solves the problems of uneven sling stress, workpiece end sag, and low distance measurement reliability leading to unstable workpiece clamping end pose estimation. This feature enables the workpiece clamping end pose and estimation reliability to be obtained before low-speed feeding, and limits the axial feeding correction amount when the estimation reliability is insufficient. This ensures that the control process does not rely on a single distance measurement value or the center point position of the lifting device, reducing the risk of erroneous feeding. This invention decomposes the chuck loading conditions into local constraints for each distributed control node, and incorporates the chuck constraint residuals into the predicted state, objective function, and control input limits within the chuck constraint DMPC algorithm. This solves the problem of traditional distributed control only coordinating the actions of each axis and not directly constraining the chuck loading state to the axial feeding. After the chuck is clamped, the tension compensation SR-UKF algorithm parameters, chuck constraint DMPC algorithm parameters, and local constraints are updated based on the loading verification results. This allows each loading result to correct subsequent control parameters in reverse, significantly reducing manual intervention, improving the stability of CNC lathe lifting and loading, and adapting to the clamping requirements of different workpiece specifications. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a flowchart of a CNC lathe lifting device position control method based on distributed control proposed in this invention; Figure 2 This is a schematic diagram of the tension compensation SR-UKF algorithm in the CNC lathe lifting device position control method based on distributed control proposed in this invention; Figure 3 This is a framework diagram of a CNC lathe lifting fixture position control system based on distributed control proposed in this invention. Detailed Implementation

[0018] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0019] refer to Figures 1-2 A method for controlling the position of a CNC lathe lifting device based on distributed control includes the following steps: Step 1: Receive the loading task from the CNC lathe, collect the status of the lifting device, the status of the workpiece to be clamped end, and the status of the chuck, and generate lifting status data; Step 2: Establish distributed control relationships based on each distributed control node, and trigger the end control process when the workpiece enters the critical feeding section of the chuck inlet at the clamping end; Step 3: Determine the equivalent control point of the workpiece to be clamped end based on the workpiece parameters, lifting point position and clamping position of the lifting device, and generate the initial clamping deviation relative to the chuck center line; Step 4: Input the hoisting status data into the tension compensation SR-UKF algorithm to estimate the workpiece's clamping end pose and estimation reliability; Step 5: Generate chuck loading conditions based on chuck status and lathe internal safety clearance, and decompose chuck loading conditions into local constraints of each distributed control node; Step 6: Input the workpiece's clamping end pose, estimated confidence level, and local constraints into the DMPC algorithm for chuck constraints, calculate the correction amount for each distributed control node, and generate a send-in permission flag, a pause waiting flag, or a safe return flag. Step 7: Perform minor correction, low-speed feeding, or safe return according to the correction amount and mark. After the chuck is clamped, generate the clamping verification result and update the tension compensation SR-UKF algorithm parameters, chuck mouth constraint DMPC algorithm parameters, and local constraints of the distributed control node based on the clamping verification result.

[0020] In this embodiment, step one specifically includes: Receives loading tasks from CNC lathes, reads workpiece parameters, lifting point positions, lifting fixture clamping positions, clamping direction, and clamping end identifiers. Workpiece parameters include workpiece number, workpiece length, workpiece diameter, and workpiece weight. Read the lathe calibration data, which includes the transformation matrix between the lathe coordinate system and the spreader coordinate system, the chuck centerline position, and the chuck inlet plane position. Connect to the traveling trolley control node, lateral movement control node, lifting control node, spreader attitude fine-tuning control node, chuck linkage control node and safety interlock control node, and perform status collection according to a unified sampling cycle; Collect the status of the lifting device, including its travel position, travel speed, travel direction, lateral position, lateral speed, lifting height, lifting speed, hook load, lifting device attitude angle, attitude fine-tuning position, sling tension, and mechanism stroke status. The status of the workpiece to be clamped end is collected, including the distance measurement value of the workpiece to be clamped end and the distance measurement reliability mark; Collect chuck status, including chuck opening, jaw position feedback, chuck clamping permission status, spindle centerline calibration status, protective door interlock status, tailstock avoidance status, emergency stop status, and safe return zone status. Using the main control clock of the CNC lathe as a reference, a unified sampling time scale is written to the status of the lifting device, the status of the workpiece to be clamped end, and the status of the chuck, and time scale alignment is performed. When the sampling timescale deviation exceeds the preset synchronization threshold, a low confidence flag is written, and short-cycle compensation is performed according to the previous valid state and the current motion speed. Data that exceeds the mechanism travel limit, the change in adjacent sampling cycles exceeds the preset change threshold, or conflicts with the chuck status is marked as abnormal data and replaced with the previous valid status. Using the transformation matrix between the lathe coordinate system and the lifting fixture coordinate system, the lifting fixture state, the workpiece clamping end state, and the chuck state are transformed to the lathe coordinate system to obtain the coordinate transformation result; The lifting status data is obtained by combining the CNC lathe loading task, workpiece parameters, lifting point position, lifting fixture clamping position, clamping end identifier, lathe calibration data, unified sampling time scale, lifting fixture status, workpiece clamping end status, chuck status, coordinate transformation results, low confidence markers, and abnormal data markers.

[0021] In this embodiment, step two specifically includes: Read the hoisting status data and extract the status of the lifting device, the status of the workpiece to be clamped end, the status of the chuck, and the coordinate transformation results; The traveling trolley control node is associated with axial feed control, the lateral movement control node is associated with lateral centering control, the lifting control node is associated with height compensation control, the spreader attitude fine-tuning control node is associated with attitude correction control, the chuck linkage control node is associated with feed permission control, and the safety interlock control node is associated with pause and retraction control, thus obtaining a distributed control relationship. The axial distance between the workpiece's clamping end and the chuck inlet is calculated using the coordinate transformation results. The chuck opening, jaw position feedback, chuck clamping permission status, protective door interlock status, tailstock avoidance status, emergency stop status, and safe return zone status are read. Read the end control process parameter table, which includes low-speed braking distance, control response distance, and chuck safety margin. The preset critical distance is taken as the larger of 1.5 times the workpiece diameter, the sum of the length to be clamped, the low-speed braking distance, the control response distance, and the chuck mouth safety margin. When the axial distance between the workpiece to be clamped end and the chuck inlet is less than the preset critical distance, and the chuck opening is not less than the sum of the workpiece diameter and the chuck inlet loading gap, the jaw position feedback is in the open state, the chuck clamping permission state is valid, the protective door interlock state is valid, the tailstock avoidance state is valid, the emergency stop state is not triggered, and the safe return area state is reachable, the chuck inlet critical feed section mark is set to valid. When the axial distance between the workpiece to be clamped end and the chuck inlet is not less than the preset critical distance, or when any chuck state does not meet the aforementioned conditions, maintain the normal lifting tool position control process and set the chuck inlet critical feed section mark to invalid. When the critical feed section mark at the chuck inlet is valid, stop using the center point of the lifting device as the basis for feed judgment, and switch the state of the workpiece to be clamped end to the input object of step three. The distributed control relationship and the critical feed segment marker at the chuck inlet are combined into the end control flow trigger result and output to step three.

[0022] In this embodiment, step three specifically includes: Read the end control flow trigger result. When the chuck inlet critical feed section mark is valid, enter the workpiece clamping end equivalent control point determination process. Extract workpiece parameters, lifting point positions, lifting tool clamping positions, clamping direction, clamping end markings, lifting tool attitude angles, workpiece clamping end distance values, lathe calibration data, and coordinate transformation results from the lifting status data; Determine the end of the workpiece to be entered into the chuck according to the clamping direction and the marking of the end to be clamped, and determine the center of the end face of that end as the equivalent control point of the end to be clamped. The position of the equivalent control point of the workpiece to be clamped end in the coordinate system is corrected by using the position of the lifting point, the clamping position of the lifting device, and the attitude angle of the lifting device. The end face position is corrected by using the distance measurement value of the workpiece to be clamped end to perform end face correction; Using the transformation matrix between the lathe coordinate system and the lifting fixture coordinate system, the equivalent control points of the workpiece to be clamped end are transformed to the lathe coordinate system; Using the position of the chuck centerline and the position of the chuck entry plane in the lathe coordinate system, calculate the lateral deviation, height deviation and axial distance of the equivalent control point of the workpiece to be clamped relative to the chuck centerline; Calculate the spatial angle between the workpiece axis and the chuck centerline, and decompose the spatial angle into pitch angle deviation and yaw angle deviation; The lateral deviation, height deviation, axial distance, pitch angle deviation, yaw angle deviation, and end face correction are combined to form the initial mounting deviation; When the end face correction exceeds the preset end face correction threshold, or any deviation in the initial mounting deviation exceeds the allowable range of the critical feed section at the chuck inlet, a low confidence flag is written to the initial mounting deviation. Specifically, the preset end face correction threshold is determined based on the repeatability error of the distance sensor at the workpiece clamping end and the end face machining allowance, taking the larger value between three times the distance repeatability error and the end face machining allowance; for example, when the distance repeatability error is 0.4 mm and the end face machining allowance is 1.5 mm, the preset end face correction threshold is 1.5 mm; the allowable range of the critical feed section at the chuck inlet is determined based on the chuck inlet loading clearance and the axial allowance at the chuck inlet, wherein the allowable range of lateral deviation is half of the chuck inlet loading clearance minus the lateral safety allowance, the allowable range of height deviation is half of the chuck inlet loading clearance minus the height safety allowance, and the allowable ranges of pitch angle deviation and yaw angle deviation are 1 degree to 2 degrees; The equivalent control point of the workpiece to be clamped end, the initial clamping deviation, the end face correction amount, and the low confidence mark are added to the hoisting status data and output to step four.

[0023] In this embodiment, step four specifically includes: Input the hoisting status data into the tension compensation SR-UKF algorithm to extract the initial clamping deviation, hoisting status, workpiece clamping end status, end face correction amount, distance measurement confidence mark, low confidence mark, abnormal data mark and the filtering result of the previous sampling period; Read the tension compensation SR-UKF algorithm parameter configuration table. The tension compensation SR-UKF algorithm parameter configuration table includes SR-UKF scale parameters, reference process noise, process noise correction coefficient, reference measurement noise, allowable deviation in the corresponding direction, and allowable compensation amount in the corresponding direction. When the filtering result of the previous sampling period is valid, the current sampling period state vector is formed according to the filtering result of the previous sampling period; when the filtering result of the previous sampling period is invalid, the current sampling period state vector is formed according to the initial mounting deviation. The state vector is arranged in the order of the configuration fields of lateral deviation, altitude deviation, axial distance, pitch angle deviation, yaw angle deviation, end droop correction, lateral deviation change, altitude deviation change, and attitude deviation change; When the filtering result of the previous sampling period is invalid and no initial droop calibration value is configured, the end droop correction is zero. The axial displacement, lateral displacement, and height displacement are calculated based on the walking speed, lateral speed, lifting speed, and uniform sampling period, respectively, and the attitude change is obtained based on the change in the attitude angle of the lifting device. Read the sling installation orientation calibration table, and match the sling tension to the left sling, right sling, front sling, and rear sling. The average sling tension is obtained by summing the tension of each sling and then dividing by the number of slings. The proportion of lateral tension difference is obtained by subtracting the tension of the left sling from the tension of the right sling and dividing by the average tension of the slings. The proportion of longitudinal tension difference is obtained by subtracting the tension of the rear sling from the tension of the front sling and dividing by the average tension of the slings. The proportion of load change is obtained by subtracting the hook load of the previous sampling period from the current hook load and dividing by the hook load of the previous sampling period. Read the preset lateral compensation coefficient, preset height compensation coefficient, preset yaw compensation coefficient, preset pitch compensation coefficient and preset sag compensation coefficient from the workpiece specification calibration table; The lateral tension compensation amount is obtained by multiplying the lateral tension difference ratio by the preset lateral compensation coefficient; the height tension compensation amount is obtained by multiplying the longitudinal tension difference ratio by the preset height compensation coefficient; the yaw angle tension compensation amount is obtained by multiplying the lateral tension difference ratio by the preset yaw compensation coefficient; the pitch angle tension compensation amount is obtained by multiplying the longitudinal tension difference ratio by the preset pitch compensation coefficient; and the end droop compensation amount is obtained by multiplying the load change ratio by the preset droop compensation coefficient. Specifically, the preset lateral compensation coefficient, preset height compensation coefficient, preset yaw compensation coefficient, preset pitch compensation coefficient, and preset sag compensation coefficient are determined based on calibration lifting tests of workpieces of the same specifications. The average ratio of the measured deviation in the corresponding direction to the proportion of tension difference or load change is taken. For example, for a workpiece with a length of 1200 mm, a diameter of 80 mm, and a weight of 35 kg, after ten calibration lifting tests, when the lateral tension difference proportion is 0.10, the corresponding average lateral deviation is 0.8 mm. Therefore, the preset lateral compensation coefficient is taken as 8. The average height deviation is 0.6 mm when the longitudinal tension difference ratio is 0.10, so the preset height compensation coefficient is 6 mm; the average yaw angle deviation is 0.08 degrees when the lateral tension difference ratio is 0.10, so the preset yaw compensation coefficient is 0.8 degrees; the average pitch angle deviation is 0.08 degrees when the longitudinal tension difference ratio is 0.10, so the preset pitch compensation coefficient is 0.8 degrees; the average end sag is 0.5 mm when the load change ratio is 0.10, so the preset sag compensation coefficient is 5 mm. Unscented sampling points are obtained based on the current sampling period state vector, covariance square root factor, state dimension and SR-UKF scale parameter, and each unscented sampling point is substituted into the state prediction rule; The state prediction rules are: axial distance minus axial displacement, lateral deviation plus lateral displacement and lateral tension compensation, height deviation plus height displacement, height tension compensation and end droop compensation, pitch angle deviation plus attitude change and pitch angle tension compensation, and yaw angle deviation plus attitude change and yaw angle tension compensation. The unmarked sampling points that have completed the state prediction are weighted and summed according to the SR-UKF mean weight to obtain the predicted state vector. The lateral deviation, height deviation, axial distance, pitch angle deviation and yaw angle deviation are extracted from the predicted state vector to form the predicted pose of the workpiece end to be clamped. The process noise covariance matrix is ​​corrected according to the proportion of tension difference and the proportion of load change. The process noise corresponding to lateral deviation and yaw angle deviation is obtained by multiplying the baseline process noise by the product of the absolute value of the proportion of lateral tension difference and the process noise correction coefficient. The process noise corresponding to altitude deviation and pitch angle deviation is obtained by multiplying the baseline process noise by the product of the absolute value of the proportion of longitudinal tension difference and the process noise correction coefficient. The process noise corresponding to end sag correction is obtained by multiplying the baseline process noise by the product of the absolute value of the proportion of load change and the process noise correction coefficient. QR decomposition and Cholesky rank-one update are performed on the corrected process noise covariance matrix to obtain the predicted covariance square root factor. The workpiece clamping end distance reference value, workpiece clamping end distance value, end face correction amount, and lateral deviation and height deviation in the initial clamping deviation are combined into the actual measurement vector. The predicted pose of the workpiece clamping end is mapped into the predicted measurement vector. The actual measurement vector is subtracted from the predicted measurement vector to obtain the information. When abnormal data is marked as valid, ranging confidence is marked as low confidence, or low confidence is marked as valid, the corresponding measurement item is treated as low confidence, and the measurement noise is taken as four times the reference measurement noise. When the direction of the innovation is consistent with the direction of the corresponding tension compensation, the tension compensation retention coefficient is one; when the direction of the innovation is opposite to the direction of the corresponding tension compensation, the tension compensation retention coefficient is half; when two consecutive sampling periods in the same direction are opposite, the tension compensation retention coefficient is zero. The tension compensation amount in the corresponding direction is corrected by the tension compensation retention coefficient, and the predicted state in the corresponding direction is recalculated with the corrected tension compensation amount. The Kalman gain is calculated based on the square root factor of the prediction covariance, the measurement noise covariance, and the innovation. The predicted state vector is then corrected based on the Kalman gain and the innovation to obtain the updated state vector. Extract the workpiece's pose at the clamping end from the updated state vector; The confidence level is estimated by subtracting the innovation deduction, tension compensation deduction, measurement noise deduction, and low confidence mark deduction from the full confidence value. The innovation deduction is obtained by dividing the absolute value of the innovation by the allowable deviation in the corresponding direction, and the tension compensation deduction is obtained by dividing the absolute value of the tension compensation by the allowable compensation in the corresponding direction. Output the workpiece's clamping end pose and estimated reliability to step six.

[0024] In this embodiment, step five specifically includes: Read the workpiece diameter and lathe internal safety clearance configuration from the chuck status and hoisting status data. The chuck status includes chuck opening, jaw position feedback, chuck clamping permission status, protective door interlock status, tailstock avoidance status, emergency stop status, and safe return zone status. The internal safety clearance configuration of the lathe includes the chuck inlet loading clearance, chuck inlet axial allowance, equipment clearance, safety return passage clearance, pitch angle allowance range, and yaw angle allowance range. The lower limit of the chuck opening is obtained by adding the workpiece diameter to the chuck opening clearance. When the chuck opening reaches the lower limit and the jaw position feedback is in the open state, the radial allowance of the chuck opening is set to valid; otherwise, it is set to invalid. When the chuck clamping permission is valid, the protective door interlock is valid, the tailstock avoidance is valid, the emergency stop is not triggered, and the safe retreat area is reachable, the chuck port interlock permission is set to valid; otherwise, it is set to invalid. Read the current value of the internal safety clearance of the lathe, and compare the current value of the internal safety clearance of the lathe with the corresponding configuration value one by one. When the current value is not less than the corresponding configuration value, the safety clearance permission is set to valid. When any current value is less than the corresponding configuration value, the safety clearance permission is set to invalid. When the chuck radial clearance, chuck interlock clearance, and safety clearance clearance are all valid, the chuck loading condition is set to valid; when any one of the clearances is invalid, the chuck loading condition is set to invalid. The chuck loading conditions are broken down into axial feeding constraints of the trolley control node. The axial feeding constraints include feeding permission, chuck inlet axial margin, axial feeding distance range and axial speed limit. The chuck loading conditions are broken down into centering boundary constraints for the lateral movement control node and the lifting control node. The centering boundary constraints include the lateral allowable range, the height allowable range, and the upper limit of the correction amount in the corresponding direction. The lateral allowable range and the height allowable range are obtained by deducting the safety margin in the corresponding direction from the chuck loading gap. The loading conditions of the chuck are broken down into attitude boundary constraints of the spreader attitude fine-tuning control node. The attitude boundary constraints include the allowable range of pitch angle, the allowable range of yaw angle, and the upper limit of attitude correction. The chuck loading conditions are broken down into chuck action constraints of the chuck linkage control node. The chuck action constraints include jaw opening and holding, clamping prohibition during axial feeding, and clamping permission after loading is completed. The chuck loading conditions are broken down into stop and retraction constraints of the safety interlock control nodes. The stop and retraction constraints include pause waiting for permission, safety retraction permission, safety retraction direction, and the current value of the lathe internal safety clearance. Specifically, the clearance between the equipment is determined based on the minimum distance between the outer edge of the chuck, the end of the tailstock, the inner wall of the protective door, and the motion envelope of the lifting device, and is not less than 30 mm; the clearance of the safety return passage is determined based on the maximum outer diameter of the workpiece, the swing allowance of the lifting device, and the safety return allowance, and is not less than 100 mm; the allowable range of pitch angle and yaw angle is determined based on the chuck inlet clearance and the length of the workpiece, and is respectively taken as 1 degree to 2 degrees; when the current value of the safety clearance inside any lathe is less than the corresponding configured value, the safety clearance permission is set to invalid; The output axial feed constraint, centering boundary constraint, attitude boundary constraint, chuck action constraint, and stop / retreat constraint serve as local constraints for each distributed control node.

[0025] In this embodiment, step six specifically includes: Input the workpiece's clamping end pose, estimated confidence level, and local constraints into the chuck constraint DMPC algorithm, and read the prediction step size, control step size, deviation weight, correction weight, chuck constraint penalty weight, feed prohibition penalty weight, confidence threshold, confidence correction coefficient, consistency weight, consistency threshold, axial speed limit, and reverse return amount limit. The local constraints are converted into chuck constraint residuals, which include lateral centering residuals, height centering residuals, axial entry residuals, pitch angle residuals, yaw angle residuals, and safety clearance residuals. Lateral alignment residual is the allowable lateral range minus the absolute value of lateral deviation; height alignment residual is the allowable height range minus the absolute value of height deviation; axial entry residual is the chuck entry axial allowance minus axial distance; pitch angle residual is the allowable pitch angle range minus the absolute value of pitch angle; yaw angle residual is the allowable yaw angle range minus the absolute value of yaw angle; and safety clearance residual is the minimum residual after subtracting the corresponding configuration value from the current value of the internal safety clearance of each lathe. When all chuck port constraint residuals are not less than zero and the chuck motion constraint is effective, the chuck port loading entry control value is set to one; when any chuck port constraint residual is less than zero or the chuck motion constraint is invalid, the chuck port loading entry control value is set to zero. Lateral deviation, altitude deviation, axial distance, pitch angle, yaw angle, and chuck constraint residuals are used as the DMPC prediction states; Set the control input of the traveling trolley control node to the axial feed correction amount, set the control input of the lateral movement control node to the lateral correction amount, set the control input of the lifting control node to the height correction amount, and set the control input of the spreader attitude fine-tuning control node to the pitch correction amount and yaw correction amount. Within the prediction step, the prediction state is recursively calculated. The next prediction value for axial distance is the current axial distance minus the axial input correction. The next prediction value for lateral deviation is the current lateral deviation plus the lateral correction. The next prediction value for altitude deviation is the current altitude deviation plus the altitude correction. The next prediction value for pitch and yaw angles is the current attitude angle plus the corresponding attitude correction. At each prediction time, the caliper constraint residual and caliper loading control value are recalculated, and the caliper constraint residual is written into the constraint out-of-bounds cost of the DMPC objective function; The objective function of DMPC consists of deviation cost, correction cost, card limit constraint out-of-bounds cost, input prohibition cost, and distributed consistency cost. The deviation cost is summed by multiplying the square of the predicted deviation by the deviation weight, and the correction cost is summed by multiplying the square of the correction by the correction weight. The cost of exceeding the limit of the chuck constraint is calculated by multiplying the square of the chuck constraint residual (which is less than zero) by the chuck constraint penalty weight and summing the costs of input prohibition. The cost of input prohibition is calculated by subtracting the chuck loading control value from one and multiplying it by the square of the axial input correction amount and summing the costs of input prohibition. The distributed consistency cost is calculated by multiplying the square of the difference in the predicted pose of the workpiece to be clamped end by each distributed control node by the consistency weight. When the chuck inlet loading control value is set to 1, the axial feed correction value ranges from zero to the upper limit of the axial speed; when the chuck inlet loading control value is zero and the safety clearance residual is not less than zero, the axial feed correction value is zero; when the safety clearance residual is less than zero, the axial feed correction value ranges from the upper limit of the reverse return amount to zero. The absolute values ​​of the lateral, altitude, pitch, and yaw corrections shall not exceed the corresponding upper limit of the correction, and the correction direction shall be opposite to the corresponding deviation direction. When the estimated confidence level is lower than the confidence level threshold, the axial correction is set to zero, and the upper limits of the lateral correction, altitude correction, pitch correction, and yaw correction are multiplied by the confidence level correction coefficient, respectively. Specifically, the prediction step size is determined based on the number of control cycles within the critical feed section at the chuck inlet, ranging from 8 to 12 sampling cycles; the control step size is ranging from 3 to 5 sampling cycles; when the uniform sampling cycle is 40 milliseconds, the prediction step size is 10, corresponding to a prediction time of 400 milliseconds, and the control step size is 3, corresponding to a control time of 120 milliseconds. Specifically, the deviation weight, correction weight, gauge constraint penalty weight, input prohibition penalty weight, and consistency weight are configured according to the control priority. The gauge constraint penalty weight is greater than the deviation weight, and the deviation weight is greater than the correction weight. For example, the deviation weight is 1, the correction weight is 0.2, the gauge constraint penalty weight is 5, the input prohibition penalty weight is 8, and the consistency weight is 2. The confidence threshold is 0.65 to 0.75, the confidence correction coefficient is 0.4 to 0.7, and the consistency threshold is set to a lateral difference of no more than 1 mm, a height difference of no more than 1 mm, and an attitude angle difference of no more than 0.3 degrees. Each distributed control node solves a local quadratic programming problem that includes its own control input constraints, and exchanges the chuck constraint residuals, the predicted pose of the workpiece to be clamped end, and the chuck loading control values. When all predicted time slots have one key control value and the consistency difference does not exceed the consistency threshold, the output is sent to the permission flag. When the chuck inlet control value is zero, the safety clearance residual is not less than zero, and there are non-zero lateral correction, altitude correction, pitch correction, or yaw correction values, the output pauses and waits for a flag. When the safety clearance residual is less than zero or the safety return permission in the stop-return constraint is valid, output a safety return flag; Output the correction amount, permission flag, pause / wait flag, or safe return flag of each distributed control node to step seven.

[0026] In this embodiment, step seven specifically includes: Receive the correction amount, pass-in permission flag, pause-wait flag and safety return flag from each distributed control node output in step six, and execute control according to the priority of the safety return flag, pause-wait flag and pass-in permission flag; When the safety return mark is valid, the trolley control node executes the reverse return amount, the lateral control node, the lifting control node and the spreader attitude fine-tuning control node execute the micro-correction corresponding to the safety return direction, and the chuck linkage control node keeps the chuck open. When the pause waiting mark is valid and the safe return mark is invalid, the axial feed correction of the traveling trolley control node is set to zero, and the lateral control node, lifting control node and spreader attitude fine-tuning control node execute the lateral correction, height correction, pitch correction and yaw correction respectively to complete the micro correction. When the feed permission mark is valid, the trolley control node performs low-speed feed according to the axial feed correction amount, the lateral control node, the lifting control node and the spreader attitude fine-tuning control node synchronously execute the corresponding correction amount, and the chuck linkage control node remains in the clamping prohibition state. When the axial distance reaches the clamping position corresponding to the length to be clamped, and the lateral deviation, height deviation, pitch angle and yaw angle are all within the allowable range of local constraints, the chuck linkage control node releases the clamping prohibition state and executes chuck clamping. After the chuck is clamped, read the closure status of the jaws, the chuck clamping permission status, the distance measurement value of the workpiece to be clamped end after clamping, and the position of the chuck center line in the jaw position feedback; The position of the workpiece to be clamped after clamping is calculated by converting the distance value of the workpiece to be clamped end after clamping, the feedback of the chuck position, and the position of the chuck center line. The clamping end of the workpiece is re-measured and compared with the position of the clamping end of the workpiece before clamping to obtain the clamping verification residual. The clamping verification residual includes lateral residual, height residual, axial residual, pitch angle residual and yaw angle residual. When the closure status in the chuck position feedback is valid, the chuck clamping permission status is valid, and the loading verification residual does not exceed the loading verification threshold, the loading verification result is set to qualified; when any condition is not met, the loading verification result is set to pending review. Read the filter update step size, measurement noise correction coefficient, constraint penalty correction coefficient, input penalty correction coefficient and constraint convergence coefficient from the parameter update configuration table; The percentage of residual error in the mounting and calibration process is obtained by dividing the residual error in the mounting and calibration process by the allowable deviation in the corresponding direction. The preset lateral compensation coefficient, preset height compensation coefficient, preset pitch compensation coefficient, and preset yaw compensation coefficient are obtained by adding the original coefficient to the product of the corresponding direction loading check residual ratio and the filter update step size, and the calculation results are restricted between the upper limit and lower limit of the parameters to obtain the tension compensation SR-UKF algorithm parameter update results. When the clamping and calibration residual exceeds the allowable deviation in the corresponding direction, the measurement noise parameter in the corresponding direction is corrected to the original measurement noise parameter multiplied by the measurement noise correction coefficient; when the clamping and calibration residual does not exceed the allowable deviation in the corresponding direction, the measurement noise parameter in the corresponding direction remains at its current value. When the card loading and verification residual exceeds the allowable deviation in the corresponding direction, the card slot constraint penalty weight is corrected to the original weight multiplied by the constraint penalty correction coefficient, and the input prohibition penalty weight is corrected to the original weight multiplied by the input penalty correction coefficient, thus obtaining the updated result of the card slot constraint DMPC algorithm parameters. When the card loading and verification residual does not exceed the allowable deviation in the corresponding direction and the card loading and verification result is qualified, the card slot constraint penalty weight and the feeding prohibition penalty weight remain at their current values. Record the direction, value, and whether the upper limit of the correction amount is reached for each correction, forming a continuous record of corrections exceeding the limit in the same direction; When the same distributed control node continuously reaches the upper limit of the correction amount in the same direction, and the card check residual still exceeds the allowable deviation, the upper limit of the correction amount of the distributed control node is corrected to the original upper limit of the correction amount multiplied by the constraint convergence coefficient, and the local constraint update result is obtained. When the card installation verification result is qualified and there is no continuous same-direction correction over-limit record in the corresponding distributed control node, the local constraint of the distributed control node remains at the current value. Specifically, the clamping verification threshold is determined based on the chuck clamping repeatability error, the workpiece end machining allowance, and the distance measurement error after clamping; the lateral residual threshold and height residual threshold are set to 1 mm to 2 mm, the axial residual threshold is set to 2 mm to 3 mm, and the pitch angle residual threshold and yaw angle residual threshold are set to 0.3 degrees to 0.5 degrees; when the lateral residual is 0.8 mm, the height residual is 0.9 mm, the axial residual is 1.5 mm, the pitch angle residual is 0.2 degrees, and the yaw angle residual is 0.2 degrees, and the closed state in the chuck position feedback is valid, the clamping verification result is set to qualified; Specifically, the filter update step size is 0.02 to 0.10, the measurement noise correction coefficient is 1.2 to 1.5, the constraint penalty correction coefficient is 1.1 to 1.3, the input penalty correction coefficient is 1.1 to 1.3, and the constraint convergence coefficient is 0.85 to 0.95. When the lateral clamping verification residual is 1.5 mm, the lateral allowable deviation is 1 mm, and the filter update step size is 0.05, the lateral clamping verification residual ratio is 1.5, the preset lateral compensation coefficient is corrected by adding 0.075 to the original coefficient, and the correction result is limited to the upper limit and lower limit of the parameter. Write the update results of the tension compensation SR-UKF algorithm parameters into the tension compensation SR-UKF algorithm parameter configuration table, write the update results of the chuck constraint DMPC algorithm parameters into the chuck constraint DMPC algorithm parameter configuration table, and write the local constraint update results into the local constraint configuration table of the distributed control node for use in the next sampling cycle or the next loading task. Output the execution results and card loading verification results.

[0027] refer to Figure 3 A CNC lathe lifting device position control system based on distributed control includes the following modules: The status generation module is used to receive loading tasks from CNC lathes, collect the status of lifting fixtures, the status of the workpiece to be clamped end and the status of chuck, and generate lifting status data. The process triggering module is used to establish a distributed control relationship based on each distributed control node, and to trigger the end control process when the workpiece waiting to be clamped enters the critical feeding section of the chuck inlet. The deviation generation module is used to determine the equivalent control point of the workpiece to be clamped end based on workpiece parameters, lifting point position and lifting fixture clamping position, and generate the initial clamping deviation relative to the chuck centerline. The tension estimation module is used to input the hoisting status data into the tension compensation SR-UKF algorithm to estimate the workpiece's clamping end pose and estimation reliability; The condition decomposition module is used to generate chuck loading conditions based on the chuck status and the internal safety clearance of the lathe, and decompose the chuck loading conditions into local constraints of each distributed control node. The collaborative control module is used to input the workpiece's clamping end pose, estimated confidence level, and local constraints into the DMPC algorithm for chuck constraints, calculate the correction amount for each distributed control node, and generate a send-in permission flag, a pause waiting flag, or a safe return flag. The verification and update module is used to perform minor corrections, slow feeding, or safe return based on the correction amount and markings. After the chuck is clamped, it generates a clamping verification result and updates the tension compensation SR-UKF algorithm parameters, chuck mouth constraint DMPC algorithm parameters, and local constraints of the distributed control nodes based on the clamping verification result.

[0028] Example 1: To verify the feasibility of this invention in practice, it was applied to an automatic loading scenario for long shaft workpieces on a CNC lathe in a workshop. The workpiece to be loaded is a 45 steel shaft part, with a length of 1200mm, a diameter of 80mm, a weight of 35kg, a clamping length of 60mm, and a distance of 800mm from the lifting point to the clamping end of the workpiece. Loading is completed collaboratively by a traveling trolley control node, a lateral movement control node, a lifting control node, a lifting device posture fine-tuning control node, a chuck linkage control node, and a safety interlock control node. The uniform sampling period is set to 40ms, the preset synchronization threshold is set to 20ms, the chuck inlet loading gap is set to 3mm, the chuck inlet axial margin is set to 52mm, the allowable ranges for lateral and altitude deviations are both set to 1.5mm, the allowable ranges for pitch and yaw deviations are both set to 1.5°, the confidence threshold is set to 0.70, the prediction step size is set to 10, the control step size is set to 3, the upper limit for axial velocity is set to 5mm / s, and the upper limit for reverse backlash is set to -8mm. The preset lateral compensation coefficient is set to 8mm, the preset altitude compensation coefficient is set to 6mm, the preset yaw compensation coefficient is set to 0.8°, the preset pitch compensation coefficient is set to 0.8°, and the preset droop compensation coefficient is set to 5mm.

[0029] In the experiment, 160 workpieces from the same batch were tested for loading verification. Method A is a conventional point-to-point control method that controls the position of the lifting device's center point alone; Method B is a method that uses the feed angle, obstacle avoidance path planning, and superimposed lifting device anti-sway control; Method C is a method that uses SR-UKF pose estimation and conventional MPC control but does not introduce tension compensation, chuck mouth constraint residuals, or loading verification feedback; the present invention is a method that uses the tension-compensated SR-UKF algorithm and the chuck mouth constraint DMPC algorithm. For each workpiece, the workpiece's position before clamping, any abnormal conditions at the chuck entry, and the loading verification results were recorded.

[0030] Table 1. Comparison of different methods in loading materials using CNC lathe lifting fixtures.

[0031] As shown in Table 1, the average lateral residual of Method A is 2.86 mm, and the average height residual is 2.41 mm, both exceeding the allowable chuck inlet range of 1.5 mm in this embodiment. This indicates that the center point of the lifting device cannot reliably represent the alignment of the workpiece to be clamped with the chuck centerline. Method B reduced the number of chuck inlet jams from 13 to 8 by adjusting the feed angle, obstacle avoidance path, and anti-sway control. However, the lateral and height residuals remained at 2.12 mm and 1.94 mm, respectively, indicating that even when only the overall path of the lifting device is constrained, the workpiece to be clamped may still deviate at the chuck inlet. After introducing SR-UKF and MPC in Method C, the average lateral residual became 1.48 mm, and the average height residual became 1.36 mm. However, 4 jams and 3 jaw collisions still occurred, indicating that without tension compensation, chuck inlet constraint residuals, and clamping verification feedback, axial feeding may still occur when the end posture does not meet the loading conditions.

[0032] This invention incorporates the proportion of sling tension difference, load variation, and end sag compensation into the tension compensation SR-UKF algorithm, enabling the workpiece clamping end pose estimation to reflect uneven sling stress and workpiece end sag. Simultaneously, it incorporates lateral alignment residuals, height alignment residuals, axial entry residuals, pitch angle residuals, yaw angle residuals, and safety clearance residuals into the chuck constraint DMPC algorithm's prediction state, objective function, and axial feed correction limits. As shown in Table 1, the average lateral residual is 0.72 mm, the average height residual is 0.68 mm, and the average attitude angle residual is 0.36°, all within the preset allowable range. The number of chuck collisions is 0, the first-time clamping pass rate reaches 98.1%, and the average loading time per piece is 37.9 s.

[0033] In conjunction with this embodiment, the beneficial effects of the present invention are as follows: by using the equivalent control point of the workpiece to be clamped end to replace the center point of the lifting device as the control object, the loading deviation caused by end misalignment is reduced; the tension compensation SR-UKF algorithm is used to handle uneven tension of the lifting sling and end sagging, reducing the impact of low-confidence ranging on pose estimation; the chuck opening constraint DMPC algorithm directly constrains the chuck opening loading conditions to the predicted state, objective function, and axial feed correction amount, so that the feed permission mark, pause waiting mark, and safe return mark have clear judgment basis; the loading verification result is used to update the algorithm parameters and local constraints in reverse, so that the subsequent loading process of similar workpieces can continuously adapt to the on-site lifting deviation.

[0034] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A CNC lathe lifting device position control method based on distributed control, characterized in that, Includes the following steps: Step 1: Receive the loading task from the CNC lathe, collect the status of the lifting device, the status of the workpiece to be clamped end, and the status of the chuck, and generate lifting status data; Step 2: Establish distributed control relationships based on each distributed control node, and trigger the end control process when the workpiece enters the critical feeding section of the chuck inlet at the clamping end; Step 3: Determine the equivalent control point of the workpiece to be clamped end based on the workpiece parameters, lifting point position and clamping position of the lifting device, and generate the initial clamping deviation relative to the chuck center line; Step 4: Input the hoisting status data into the tension compensation SR-UKF algorithm to estimate the workpiece's clamping end pose and estimation reliability; Step 5: Generate chuck loading conditions based on chuck status and lathe internal safety clearance, and decompose chuck loading conditions into local constraints of each distributed control node; Step 6: Input the workpiece's clamping end pose, estimated confidence level, and local constraints into the DMPC algorithm for chuck constraints, calculate the correction amount for each distributed control node, and generate a send-in permission flag, a pause waiting flag, or a safe return flag. Step 7: Perform minor correction, low-speed feeding, or safe return according to the correction amount and mark. After the chuck is clamped, generate the clamping verification result and update the tension compensation SR-UKF algorithm parameters, chuck mouth constraint DMPC algorithm parameters, and local constraints of the distributed control node based on the clamping verification result.

2. The CNC lathe lifting device position control method based on distributed control according to claim 1, characterized in that, Step one specifically includes: The system receives loading tasks from a CNC lathe, acquires workpiece parameters, lifting point positions, lifting fixture clamping positions, and lathe calibration data. The workpiece parameters include workpiece diameter, workpiece length, and workpiece weight. The lathe calibration data includes the transformation matrix between the lathe coordinate system and the lifting fixture coordinate system, the chuck centerline position, and the chuck inlet plane position. The status of the lifting device, the status of the workpiece to be clamped end, and the status of the chuck are collected. The status of the lifting device includes the traveling position, traveling speed, lateral position, lateral speed, lifting height, lifting speed, hook load, lifting device attitude angle, and sling tension. The state of the workpiece to be clamped end includes the distance measurement value of the workpiece to be clamped end and the distance measurement reliability mark; The chuck status includes chuck opening degree, chuck position feedback, chuck clamping permission status, spindle center line calibration status, protective door interlock status, tailstock avoidance status, emergency stop status, and safe return zone status. A unified sampling time stamp is written to the status of the lifting device, the status of the workpiece to be clamped end, and the status of the chuck. When the sampling time stamp deviation exceeds the preset synchronization threshold, a low confidence flag is written. When the collected data exceeds the mechanism travel limit, the change in adjacent sampling cycles exceeds the preset change threshold, or there is a conflict with the chuck status, write an abnormal data flag. Using the transformation matrix between the lathe coordinate system and the lifting fixture coordinate system, the lifting fixture state, the workpiece clamping end state, and the chuck state are transformed to the lathe coordinate system to obtain the coordinate transformation result; The lifting status data is obtained by combining the CNC lathe loading task, workpiece parameters, lifting point position, lifting fixture clamping position, lathe calibration data, lifting fixture status, workpiece clamping end status, chuck status, coordinate transformation results, low confidence markers, and abnormal data markers.

3. The CNC lathe lifting device position control method based on distributed control according to claim 1, characterized in that, Step two specifically includes: The traveling trolley control node is associated with axial feed control, the lateral movement control node is associated with lateral centering control, the lifting control node is associated with height compensation control, the spreader attitude fine-tuning control node is associated with attitude correction control, the chuck linkage control node is associated with feed permission control, and the safety interlock control node is associated with pause and retraction control, thus obtaining a distributed control relationship. The axial distance between the workpiece's clamping end and the chuck inlet is calculated using the coordinate transformation results; The preset critical distance is taken as the larger of 1.5 times the workpiece diameter, the sum of the length to be clamped, the low-speed braking distance, the control response distance, and the chuck mouth safety margin. When the axial distance is less than the preset critical distance, and the chuck opening is not less than the sum of the workpiece diameter and the chuck inlet loading gap, the chuck position feedback is in the open state, the chuck clamping permission state is valid, the protective door interlock state is valid, the tailstock avoidance state is valid, the emergency stop state is not triggered, and the safe return area state is reachable, the chuck inlet critical feed section mark is set to valid. When the critical feed section mark at the chuck inlet is valid, the use of the spreader center point position as the feed judgment criterion is stopped, and the end control process is triggered.

4. The CNC lathe lifting device position control method based on distributed control according to claim 1, characterized in that, Step three specifically includes: Determine the end of the workpiece to be entered into the chuck according to the clamping direction and the marking of the end to be clamped, and determine the center of the end face of that end as the equivalent control point of the end to be clamped. The position of the equivalent control point of the workpiece to be clamped end in the coordinate system is corrected by using the position of the lifting point, the clamping position of the lifting device, and the attitude angle of the lifting device. The end face position is corrected by using the distance measurement value of the workpiece to be clamped end to perform end face correction; Using the transformation matrix between the lathe coordinate system and the lifting fixture coordinate system, the equivalent control points of the workpiece to be clamped end are transformed to the lathe coordinate system; Calculate the lateral deviation, height deviation, and axial distance of the equivalent control point of the workpiece to be clamped relative to the chuck centerline, and calculate the pitch angle deviation and yaw angle deviation between the workpiece axis and the chuck centerline; The lateral deviation, height deviation, axial distance, pitch angle deviation, yaw angle deviation, and end face correction are combined to form the initial mounting deviation; When the end face correction exceeds the preset end face correction threshold, or any deviation in the initial mounting deviation exceeds the allowable range of the critical feed section at the chuck inlet, a low confidence flag is written to the initial mounting deviation.

5. The CNC lathe lifting fixture position control method based on distributed control according to claim 1, characterized in that, Step four specifically includes: The state vector of the tension-compensated SR-UKF algorithm includes lateral deviation, altitude deviation, axial distance, pitch deviation, yaw deviation, end droop correction, lateral deviation change, altitude deviation change, and attitude deviation change. The proportion of lateral tension difference is obtained by subtracting the tension of the left sling from the tension of the right sling and dividing by the average tension of the slings. The proportion of longitudinal tension difference is obtained by subtracting the tension of the rear sling from the tension of the front sling and dividing by the average tension of the slings. The proportion of load change is obtained by subtracting the hook load of the previous sampling period from the current hook load and dividing by the hook load of the previous sampling period. The lateral tension compensation amount is obtained by multiplying the lateral tension difference ratio by the preset lateral compensation coefficient; the height tension compensation amount is obtained by multiplying the longitudinal tension difference ratio by the preset height compensation coefficient; the yaw angle tension compensation amount is obtained by multiplying the lateral tension difference ratio by the preset yaw compensation coefficient; the pitch angle tension compensation amount is obtained by multiplying the longitudinal tension difference ratio by the preset pitch compensation coefficient; and the end droop compensation amount is obtained by multiplying the load change ratio by the preset droop compensation coefficient. By incorporating each tension compensation amount into the SR-UKF state prediction rule, the predicted pose of the workpiece's clamping end is obtained. The process noise covariance matrix is ​​corrected according to the proportion of tension difference and load change, and the predicted covariance square root factor is obtained through QR decomposition and Cholesky rank-one update.

6. The CNC lathe lifting device position control method based on distributed control according to claim 5, characterized in that, The tension compensation SR-UKF algorithm specifically includes: The distance measurement value of the workpiece to be clamped end, the end face correction amount, and the lateral deviation and height deviation in the initial clamping deviation are combined into the actual measurement vector; The predicted pose of the workpiece to be clamped end is mapped to a predicted measurement vector, and the information is obtained by subtracting the predicted measurement vector from the actual measurement vector. When the abnormal data is marked as valid, the ranging confidence mark is marked as low confidence, or the low confidence mark is valid, the measurement noise of the corresponding measurement item is taken as four times the reference measurement noise. When the direction of the innovation is consistent with the direction of the corresponding tension compensation, the tension compensation retention coefficient is one; when the direction of the innovation is opposite to the direction of the corresponding tension compensation, the tension compensation retention coefficient is half; when two consecutive sampling periods in the same direction are opposite, the tension compensation retention coefficient is zero. The tension compensation amount in the corresponding direction is corrected according to the tension compensation retention coefficient, and the predicted state in the corresponding direction is recalculated with the corrected tension compensation amount. The Kalman gain is calculated based on the square root factor of the prediction covariance, the measurement noise covariance, and the innovation. The prediction state vector is then corrected based on the Kalman gain and the innovation to obtain the workpiece's pose at the clamping end. The confidence level is estimated by subtracting the innovation deduction item, tension compensation deduction item, measurement noise deduction item, and low confidence mark deduction item from the full confidence value; the innovation deduction item is obtained by dividing the absolute value of the innovation by the allowable deviation in the corresponding direction, and the tension compensation deduction item is obtained by dividing the absolute value of the tension compensation by the allowable compensation in the corresponding direction.

7. The CNC lathe lifting fixture position control method based on distributed control according to claim 1, characterized in that, Step five specifically includes: The lower limit of the chuck opening is obtained by adding the workpiece diameter to the chuck opening clearance. When the chuck opening reaches the lower limit and the jaw position feedback is in the open state, the radial allowable setting of the chuck opening is valid. When the chuck clamping permission is valid, the protective door interlock is permitted, the tailstock avoidance is valid, the emergency stop is not triggered, and the safe retreat area is reachable, the chuck port interlock permission is set to valid. When the current values ​​of the internal safety clearances of the lathe are not less than the corresponding configured values, the safety clearance permission is set to valid; When the chuck radial clearance, chuck interlock clearance, and safety clearance clearance are all valid, the chuck loading condition is set to valid. The chuck loading conditions are broken down into axial feeding constraints, centering boundary constraints, attitude boundary constraints, chuck motion constraints, and stop / retract constraints, which serve as local constraints for each distributed control node.

8. The CNC lathe lifting device position control method based on distributed control according to claim 1, characterized in that, Step six specifically includes: Configure the confidence threshold, confidence correction coefficient, consistency threshold, axial speed limit, and reverse backoff amount limit for the DMPC algorithm with caliper port constraint. The local constraints are converted into chuck constraint residuals, which include lateral centering residuals, height centering residuals, axial entry residuals, pitch angle residuals, yaw angle residuals, and safety clearance residuals. Lateral deviation, altitude deviation, axial distance, pitch angle, yaw angle, and chuck constraint residuals are used as the DMPC prediction states; When the residual constraint of each chuck port is not less than zero and the chuck action constraint is effective, the chuck port loading control value is set to one; otherwise, it is set to zero. At each prediction time, the chuck constraint residual and chuck loading control value are recalculated, and the chuck constraint residual is written into the chuck constraint out-of-bounds cost of the DMPC objective function; The DMPC objective function includes deviation cost, correction cost, card constraint out-of-bounds cost, input prohibition cost, and distributed consistency cost. When the chuck inlet loading control value is set to 1, the axial feed correction value ranges from zero to the upper limit of the axial speed; when the chuck inlet loading control value is zero and the safety clearance residual is not less than zero, the axial feed correction value is zero; when the safety clearance residual is less than zero, the axial feed correction value ranges from the upper limit of the reverse return amount to zero. When the estimated confidence level is lower than the confidence level threshold, the axial correction is set to zero, and the upper limits of the lateral correction, altitude correction, pitch correction, and yaw correction are multiplied by the confidence level correction coefficient, respectively. Each distributed control node solves a local quadratic programming problem and exchanges the chuck constraint residuals, the predicted pose of the workpiece to be clamped end, and the chuck loading control values. When all predicted chuck loading entry control values ​​are set to one and the consistency difference does not exceed the consistency threshold, an input permission flag is output; when the chuck loading entry control value is zero, the safety clearance residual is not less than zero, and there are non-zero lateral corrections, altitude corrections, pitch corrections, or yaw corrections, a pause waiting flag is output; when the safety clearance residual is less than zero or the safety return permission in the stop-and-go constraint is valid, a safety return flag is output.

9. The CNC lathe lifting device position control method based on distributed control according to claim 1, characterized in that, Step seven specifically includes: When the safety return flag is valid, perform a minor correction corresponding to the safety return direction; When the pause-wait marker is valid and the safe return marker is invalid, the axial feed correction is set to zero, and the lateral, altitude, pitch, and yaw corrections are executed. When the feed permission mark is valid, perform low-speed feed according to the axial feed correction amount, and simultaneously perform lateral correction, altitude correction, pitch correction and yaw correction. After the chuck is clamped, the position of the workpiece to be clamped is recalculated based on the distance value of the workpiece to be clamped end, the feedback of the jaw position, and the position of the chuck center line. The clamping end of the workpiece is re-measured and compared with the position of the clamping end of the workpiece before clamping to obtain the clamping verification residual. The clamping verification residual includes lateral residual, height residual, axial residual, pitch angle residual and yaw angle residual. The loading and checking results are generated based on the loading and checking residuals and the feedback of the jaw positions. Tension compensation coefficients and measurement noise parameters based on the SR-UKF algorithm for tension compensation based on mounting verification residual correction; Based on whether the residual of the card loading verification exceeds the allowable deviation in the corresponding direction, the card opening constraint penalty weight and the input prohibition penalty weight of the DMPC algorithm are corrected. Record the direction, value, and whether the upper limit of the correction amount is reached for each correction, forming a continuous record of corrections exceeding the limit in the same direction; Based on continuous same-direction correction of out-of-limit records, the local constraints of the corresponding distributed control nodes are corrected.

10. A CNC lathe lifting fixture position control system based on distributed control, applied to the CNC lathe lifting fixture position control method based on distributed control as described in any one of claims 1 to 9, characterized in that, Includes the following modules: The status generation module is used to receive loading tasks from CNC lathes, collect the status of lifting fixtures, the status of the workpiece to be clamped end and the status of chuck, and generate lifting status data. The process triggering module is used to establish a distributed control relationship based on each distributed control node, and to trigger the end control process when the workpiece waiting to be clamped enters the critical feeding section of the chuck inlet. The deviation generation module is used to determine the equivalent control point of the workpiece to be clamped end based on workpiece parameters, lifting point position and lifting fixture clamping position, and generate the initial clamping deviation relative to the chuck centerline. The tension estimation module is used to input the hoisting status data into the tension compensation SR-UKF algorithm to estimate the workpiece's clamping end pose and estimation reliability; The condition decomposition module is used to generate chuck loading conditions based on the chuck status and the internal safety clearance of the lathe, and decompose the chuck loading conditions into local constraints of each distributed control node. The collaborative control module is used to input the workpiece's clamping end pose, estimated confidence level, and local constraints into the DMPC algorithm for chuck constraints, calculate the correction amount for each distributed control node, and generate a send-in permission flag, a pause waiting flag, or a safe return flag. The verification and update module is used to perform minor corrections, slow feeding, or safe return based on the correction amount and markings. After the chuck is clamped, it generates a clamping verification result and updates the tension compensation SR-UKF algorithm parameters, chuck mouth constraint DMPC algorithm parameters, and local constraints of the distributed control nodes based on the clamping verification result.

Images