An adaptive workpiece processing apparatus and method

Abstract

This invention discloses an adaptive workpiece machining device and method, belonging to the field of automated machining technology. The device includes a linear motor, a pressure roller, a rotary motor, a machining mechanism, a servo driver, and a PLC controller. The method includes workpiece contour recognition and cam table establishment, speed planning, normal machining, and adaptive optimization steps. In the workpiece contour recognition stage, workpiece contour data is acquired through constant pressure follow-up and an electronic cam table is generated. In the speed planning stage, the target angular velocity at each angular position is calculated based on the equivalent radius, and a speed planning table is generated. In the normal machining stage, a composite control strategy combining electronic cam synchronization, angular velocity feedforward, linear velocity closed-loop, and pressure closed-loop is adopted. In the adaptive optimization stage, iterative optimization of control parameters is achieved through recording deviations, analyzing deviations, and online correction. This invention can adapt to edge machining of workpieces of arbitrary shapes, requires no pre-programming, and achieves high accuracy in linear velocity and pressure control.

Description

Technical Field

[0001] This invention belongs to the field of automated processing technology, specifically relating to an adaptive workpiece processing device and method. Background Technology

[0002] In furniture manufacturing, wood processing, and metalworking, edge finishing processes such as gluing, edge banding, and sanding are common production steps. For round workpieces, due to their regular contours, the relative position and speed between the workpiece edge and the processing mechanism are easy to control during processing, resulting in uniform processing effects. However, in actual production, there are many non-circular workpieces, including elliptical, polygonal, and irregularly shaped workpieces composed of straight and circular segments. The curvature of these workpieces varies with their angular position, posing significant technical challenges to edge processing.

[0003] In existing technologies, edge machining of non-circular workpieces typically employs the following methods: one is to pre-program the machining process based on the workpiece's design drawings and input the workpiece contour data into a CNC system for machining; the other is to use a contouring mechanism, where the machining mechanism follows the workpiece contour through mechanical servoing. The former method requires separate machining programs for different workpiece shapes, necessitating reprogramming when workpiece types change, resulting in poor production flexibility. Furthermore, it demands high precision in workpiece placement, as deviations in workpiece placement can lead to a decrease in machining quality. While the latter method offers some adaptability, the mechanical contouring mechanism has limited response speed, making it difficult to adapt to workpieces with drastic changes in contour curvature, and wear on the mechanical structure can affect contouring accuracy.

[0004] In terms of processing speed control, most existing technologies use constant angular velocity rotation to drive the workpiece. For non-circular workpieces, constant angular velocity rotation causes the linear velocity of each point on the workpiece edge relative to the processing mechanism to vary with the equivalent radius. Locations with a larger equivalent radius have a higher linear velocity, while locations with a smaller equivalent radius have a lower linear velocity. This uneven linear velocity directly affects processing quality. For example, during adhesive application, locations with higher linear velocities have thinner adhesive layers, while locations with lower linear velocities have thicker adhesive layers. Similarly, during grinding, locations with higher linear velocities require less grinding, while locations with lower linear velocities require more grinding, ultimately resulting in uneven processing quality.

[0005] In terms of control strategies, most existing technologies employ simple feedback control. Feedback control requires waiting for a deviation to occur before initiating correction, and the correction action also needs to overcome communication and motor response delays to take effect, resulting in the actual output lagging behind the target value. When the workpiece contour curvature changes abruptly, the target value also changes abruptly, causing the feedback controller to generate a large correction amount, easily leading to overshoot and oscillation, affecting machining quality. Furthermore, the control parameters in existing technologies are usually determined during the system debugging phase and remain unchanged, unable to be automatically adjusted according to actual machining conditions, making it difficult to adapt to changes in workpiece characteristics and equipment status. Summary of the Invention

[0006] To address the problems existing in the background art, the present invention provides an adaptive workpiece processing device, comprising: A linear motor includes an integrated mover, a guide rail, and a grating ruler. The integrated mover can move controllably along the guide rail, and the grating ruler detects the position of the integrated mover. A pressure roller, mounted on the integrated mover, is used to contact the edge of the workpiece; an encoder is connected to the pressure roller to detect the rotational speed of the pressure roller; a pressure sensor is set on the support structure of the pressure roller to detect the contact pressure between the pressure roller and the edge of the workpiece. A rotary motor connects to the workpiece via a rotating shaft and drives the workpiece to rotate; an encoder is connected to the rotary motor and is used to detect the rotation angle of the workpiece. The processing mechanism, mounted on the integrated mover and located on one side of the pressure roller, is used to process the edge of the workpiece; A linear servo driver, electrically connected to the linear motor and the grating ruler, is used to control the position of the linear motor; A rotary servo driver, electrically connected to the rotary motor and encoder, is used to control the rotational speed of the rotary motor; The PLC controller communicates with the linear servo driver and rotary servo driver via a bus and receives signals from the encoder and pressure sensor. The PLC controller stores an electronic cam table and a speed planning table. The electronic cam table records the correspondence between the workpiece rotation angle and the linear motor position, and the speed planning table records the target angular velocity corresponding to different workpiece rotation angles. The PLC controller controls the position of the linear motor to follow the workpiece rotation angle according to the electronic cam table, and controls the speed of the rotary motor according to the speed planning table to maintain a constant pressure and linear velocity of the pressure roller on the workpiece.

[0007] In a preferred embodiment, the PLC controller communicates with the linear servo driver and the rotary servo driver via an EtherCAT bus, and obtains the position of the linear motor and the angle and speed information of the rotary motor by reading PDO data.

[0008] In a preferred embodiment, the encoder is mounted on the shaft of the pressure roller, and its signal output terminal is connected to the PLC controller; the signal output terminal of the pressure sensor is connected to the PLC controller to realize pressure closed-loop control.

[0009] This invention also provides an adaptive workpiece machining method, comprising the following steps: S1. Workpiece contour recognition and cam table establishment: The PLC controller controls the linear motor to move so that the pressure roller contacts the edge of the workpiece to the preset pressure. The rotary motor drives the workpiece to rotate one revolution at low speed. During the rotation, the PLC controller adjusts the position of the linear motor in real time through pressure closed-loop control to maintain constant contact pressure. It synchronously records each rotation angle and the corresponding linear motor position, and generates an electronic cam table through interpolation algorithm. S2. Speed ​​Planning: The PLC controller calculates the equivalent radius of the workpiece contour at each angular position based on the data from the electronic cam table, and then calculates the required rotational angular velocity at each angular position based on the target linear velocity and the equivalent radius, generating a speed planning table. S3. Normal processing: The rotary motor is the main shaft and the linear motor is the slave shaft. The PLC controller realizes the synchronous control of the linear motor position and the workpiece rotation angle according to the electronic cam table. The speed of the rotary motor is fed forward according to the speed planning table. Closed-loop correction is performed by combining the pressure roller linear speed detected by encoder 1 and the contact pressure detected by pressure sensor to keep the pressure and linear speed of the pressure roller on the workpiece constant during the processing. S4. Adaptive Optimization: During the processing in step S3, the PLC controller continuously records the deviation between the actual pressure and actual linear speed and the set values, and corrects the electronic cam table and speed planning table online to gradually optimize the control parameters.

[0010] Furthermore, step S1 includes the following sub-steps: S11. Initialization: The PLC controller sends a position command to the linear servo driver, controlling the linear motor to move the pressure roller towards the workpiece at a first speed; when the pressure sensor detects a pressure value greater than zero, it switches to a second speed lower than the first speed to continue moving, and monitors the pressure change rate in real time; when the pressure value reaches the preset initial contact pressure... The movement will stop when the pressure change rate exceeds the set threshold during the movement; if the movement rate exceeds the set threshold during the movement, the movement will stop and an alarm will be triggered. S12, Low-speed scanning: The PLC controller sends a speed command to the rotary servo driver, controlling the rotary motor to drive the workpiece to rotate at a low speed for one revolution. S13. Constant Pressure Follow-up: During the workpiece rotation process, the PLC controller reads the pressure value from the pressure sensor at fixed intervals and compares the pressure value with the set value. By comparison, a PID algorithm is used to calculate the position adjustment of the linear motor, and a position adjustment command is sent to the linear servo driver to maintain the pressure of the pressure roller on the workpiece at the set value. Within the allowable deviation range; S14. Data Acquisition: During the workpiece rotation process, the PLC controller synchronously reads the rotation angle value output by encoder 2. The linear motor position value output by the grating ruler Stored as angle-position data pairs; S15. Cam table generation: After the workpiece rotates one revolution, the PLC controller processes the collected data points. Perform spline interpolation to generate a smooth electronic cam table. And store.

[0011] Furthermore, step S2 includes the following sub-steps: S21. Equivalent radius calculation: The PLC controller reads various angles from the electronic cam table. Corresponding position value The equivalent radius is calculated using the three-point circular arc fitting method. Take three adjacent angle points , , and their corresponding position values , , Convert the three points to coordinates in a rectangular coordinate system, fit an arc passing through the three points, and the radius of this arc is the angle. equivalent radius of the workpiece profile ; S22, Angular velocity calculation: Set the target linear velocity The PLC controller calculates the required rotational angular velocity for each angular position using the following formula. : ; in, For angle The required rotational angular velocity at that point, in rad / s; The target linear velocity is expressed in mm / s. For angle The equivalent radius at the location, in mm; S23. Speed ​​planning table generation: The PLC controller will generate speed planning tables for each angle. With the corresponding angular velocity Create and store the speed planning table.

[0012] Furthermore, step S3 includes the following sub-steps: S31, Electronic Cam Synchronization: The PLC controller reads the current rotation angle output by encoder 2 in real time. Query the electronic cam table to obtain the corresponding target position of the linear motor. Send position commands to the linear servo driver to make the position of the linear motor change synchronously with the rotation angle of the workpiece; S32, Angular velocity feedforward: The PLC controller feeds forward the angular velocity based on the current rotation angle. Query the velocity planning table to obtain the target angular velocity According to system delay time Response time of rotating electric motor Calculate feedforward time ,in advance Time sends speed commands to the rotary servo drive; S33, Linear velocity closed-loop: The PLC controller reads the pressure roller speed output by encoder one and calculates the actual linear velocity based on the pressure roller radius. The actual linear velocity With the target linear velocity In comparison, the angular velocity correction amount is calculated using a PI control algorithm. The speed command superimposed on the rotating motor; the angular velocity correction amount Calculate using the following formula: ; in, ; This is the angular velocity correction value, and the unit is rad / s; This is the proportional control coefficient; These are integral control coefficients; Linear velocity deviation, in mm / s; The target linear velocity is expressed in mm / s. This refers to the actual linear velocity, in mm / s. S34, Pressure Closed Loop: The PLC controller reads the pressure value from the pressure sensor. If the pressure deviates from the set value... If the position exceeds the allowable range, the linear motor position compensation amount is calculated and sent to the linear servo driver for fine-tuning.

[0013] Furthermore, in step S32, the feedforward time... Calculate using the following formula: ; in, The feedforward time is expressed in seconds (s). The system communication and processing delay time is measured in seconds (s). The response time constant of a rotating electrical machine is expressed in seconds (s). Furthermore, step S4 includes the following sub-steps: S41. Deviation Recording: During the processing in step S3, the PLC controller continuously reads the actual pressure value detected by the pressure sensor and the actual linear velocity calculated by the encoder. Calculate the actual pressure and the set value respectively. Deviation and actual linear velocity With the target linear velocity The deviation, and according to the rotation angle Record storage; S42. Deviation Analysis: After the workpiece rotates one revolution, the PLC controller counts the pressure deviation value and linear velocity deviation value at each angular position and identifies the angular range with large deviation. S43. Online correction: The PLC controller corrects the linear motor position value at the corresponding angle position in the electronic cam table according to the pressure deviation, and corrects the angular velocity value at the corresponding angle position in the speed planning table according to the linear velocity deviation. S44. Iterative optimization: Repeat steps S3 and S41-S43. After multiple processing cycles, the electronic cam table and speed planning table gradually converge to the optimal value, completing the adaptive optimization of the control parameters.

[0014] The beneficial effects achieved by this invention are as follows: This invention designs an adaptive workpiece processing device and method. By establishing workpiece contour recognition and an electronic cam table, it automatically identifies and synchronously controls the position of workpieces of arbitrary shapes. In the contour recognition stage, the pressure roller contacts the workpiece edge with constant pressure and completes contour data acquisition as the workpiece rotates one revolution. An electronic cam table is then generated using a spline interpolation algorithm. The electronic cam table records the correspondence between the workpiece rotation angle and the linear motor position. In subsequent processing stages, the linear motor position changes synchronously with the workpiece rotation angle according to the electronic cam table, ensuring that the processing mechanism and the workpiece edge maintain a constant relative position. This technical solution allows the invention to adapt to the edge processing of circular, elliptical, polygonal, and arbitrarily irregular shaped workpieces without rewriting processing programs or changing fixtures for different workpiece shapes, and without prior knowledge of the workpiece's precise dimensions. The system can automatically identify and adapt to the actual shape characteristics of the workpiece.

[0015] This invention achieves constant control of the linear velocity of the pressure roller relative to the workpiece edge through speed planning based on the equivalent radius. For non-circular workpieces, if the rotary motor rotates at a constant angular velocity, the linear velocity of each point on the workpiece edge relative to the pressure roller will vary with the equivalent radius, resulting in uneven processing. This invention calculates the equivalent radius at each angular position using a three-point circular arc fitting method based on data from an electronic cam meter, and then calculates the required rotational angular velocity at each angular position based on the inverse relationship between the target linear velocity and the equivalent radius, generating a speed planning table. During processing, the angular velocity of the rotary motor is adjusted in real time according to the speed planning table, decreasing the angular velocity at positions with a large equivalent radius and increasing the angular velocity at positions with a small equivalent radius, thereby maintaining a constant linear velocity. A constant linear velocity is a key factor in ensuring uniform processing quality. Too low a linear velocity will result in excessively thick adhesive application or excessive sanding, while too high a linear velocity will result in insufficient adhesive application or insufficient sanding. Therefore, this invention can achieve uniform processing results when processing workpieces of different shapes.

[0016] This invention improves the dynamic response performance of a system by combining feedforward and feedback control. Feedforward control predicts changes in the target angular velocity based on the speed planning table, issuing speed commands in advance to compensate for communication delays and motor response delays, ensuring that motor speed changes are synchronized with changes in contour curvature. Feedback control includes a linear velocity closed loop and a pressure closed loop. The linear velocity closed loop corrects the errors of the feedforward control using a PI control algorithm, while the pressure closed loop compensates for errors in the electronic cam gauge in real time. Feedforward control undertakes the main speed regulation task, while feedback control only needs to correct feedforward errors and random disturbances. The combination of the two results in a fast and stable system response, less prone to overshoot and oscillations in regions of abrupt changes in contour curvature. Compared to simple feedback control, this composite control strategy offers better dynamic performance and steady-state accuracy, making it suitable for machining workpieces with complex contours and drastic curvature changes.

[0017] This invention achieves online correction and continuous improvement of control parameters through adaptive optimization. Since contour recognition is performed under low-speed scanning conditions, the generated electronic cam table and speed planning table may contain acquisition errors due to controller response lag, which are particularly noticeable in areas with drastic changes in contour curvature. This invention continuously records pressure and linear velocity deviations during normal processing, analyzes the distribution of deviations according to rotation angles, identifies angle ranges with large deviations, and performs online corrections to the electronic cam table and speed planning table. Through iterative optimization over multiple processing cycles, the electronic cam table and speed planning table gradually converge to their optimal values, acquisition and system errors are gradually eliminated, and pressure and linear velocity control accuracy is continuously improved. Adaptive optimization enables the system to have self-learning capabilities, automatically adapting to changes in the actual characteristics of the workpiece and processing conditions without manual intervention. It can also compensate for system drift caused by mechanical wear, temperature changes, and other factors after long-term equipment operation, ensuring the consistency and stability of processing quality. Attached Figure Description

[0018] Figure 1 This is a comparison chart of the standard deviation of linear velocity and volatility of Examples 1, 2, and 3 with Comparative Example 1. It is presented in the form of a grouped bar chart, with the left Y-axis representing the standard deviation of linear velocity and the right Y-axis representing the volatility of linear velocity.

[0019] Figure 2 This is a comparison graph of the pressure standard deviation of Example 1 and Comparative Example 2 as a function of the number of iterations. It is presented in the form of a line graph with confidence interval filling bands.

[0020] Figure 3 This is a comparison diagram of the linear velocity dynamic response at the vertex of a regular hexagon between Example 2 and Comparative Example 3, using step response curves and indicating the overshoot.

[0021] Figure 4 The above are comparison diagrams of the electronic cam table before and after correction in Example 3. Sub-figure (a) is a comparison diagram of the workpiece contour in polar coordinates and the cam table trajectory before and after correction, and sub-figure (b) is a double Y-axis curve diagram showing the changes of position correction and angular velocity correction with angle.

[0022] Figure 5 This is a comprehensive performance comparison chart of Examples 1, 2, and 3 with Comparative Examples 1, 2, and 3. Sub-figure (a) is a horizontal bar chart of linear velocity standard deviation, sub-figure (b) is a horizontal bar chart of pressure standard deviation, and sub-figure (c) is a horizontal bar chart of processing uniformity index.

[0023] Figure 6 This is a structural diagram of an adaptive workpiece processing device according to the present invention.

[0024] Figure 7 This is a control principle diagram of an adaptive workpiece processing device according to the present invention.

[0025] Numbering on the map: 1. Linear motor; 10. Integrated mover; 11. Guide rail; 12. Grating ruler; 100. Worktable; 2. Pressure roller; 21. Encoder 1; 22. Pressure sensor; 3. Workpiece; 4. Rotary motor; 41. Encoder 2; 5. Machining mechanism; 6. Rotary servo driver; 7. Linear servo driver; 8. PLC controller; 9. EtherCAT bus. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. In addition, the forms of the various structures described in the following embodiments are merely illustrative. The present invention is not limited to the structures described in the following embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Reference Figures 6-7 This invention provides an adaptive workpiece machining device that enables adaptive machining of the edges of workpieces of arbitrary shapes without requiring reprogramming or fixture replacement for different workpiece shapes. The adaptive workpiece machining device includes a linear motor 1, a pressure roller 2, a rotary motor 4, a machining mechanism 5, a linear servo driver 7, a rotary servo driver 6, and a PLC controller 8. The linear motor 1 is mounted on a worktable 100 and includes an integrated mover 10, a guide rail 11, and a grating ruler 12. The integrated mover 10 moves controllably along the guide rail 11, and the grating ruler 12 is installed inside the linear motor 1 to detect the position of the integrated mover 10. The grating ruler 12 is a high-precision displacement measuring element that detects displacement through optical principles with a resolution down to the μm level. Its detection signal is fed back to the linear servo driver 7, forming a closed-loop position control.

[0028] The pressure roller 2 is mounted on the integrated mover 10 and is used to contact the edge of the workpiece 3. An encoder 21 is connected to the pressure roller 2 and is used to detect the rotational speed of the pressure roller 2. A pressure sensor 22 is set on the support structure of the pressure roller 2 and is used to detect the contact pressure between the pressure roller 2 and the edge of the workpiece 3. The encoder 21 is mounted on the shaft of the pressure roller 2. When the workpiece 3 rotates, causing the pressure roller 2 to rotate passively, the encoder 21 outputs a pulse signal proportional to the rotational speed. By calculating the number of pulses per unit time, the rotational speed of the pressure roller 2 can be obtained. Combined with the radius of the pressure roller 2, the linear velocity at the contact point between the pressure roller 2 and the workpiece 3 can be calculated. The pressure sensor 22 can be a strain gauge force sensor or a piezoelectric force sensor. Its signal output terminal is connected to the PLC controller 8 to provide real-time feedback of the contact pressure for closed-loop pressure control. The setting of the pressure sensor 22 allows the system to sense the contact state between the pressure roller 2 and the workpiece 3 in real time, providing feedback signals for subsequent constant pressure control.

[0029] Rotary motor 4 is connected to workpiece 3 via a rotating shaft and drives workpiece 3 to rotate. Encoder 41 is connected to rotary motor 4 and is used to detect the rotation angle of workpiece 3. Rotary motor 4, as the spindle motor, determines the reference for the entire machining process through its speed and angular position. Encoder 41 typically uses an incremental encoder or an absolute encoder. An incremental encoder obtains the relative position by counting the number of pulses, while an absolute encoder directly outputs the absolute value of the current angle. The angle signal from encoder 41 serves as the reference signal for the synchronous control of the electronic cam, and the position of linear motor 1 follows this angle signal for synchronous movement.

[0030] The processing mechanism 5 is mounted on the integrated mover 10, located on one side of the pressure roller 2, and is used to process the edge of the workpiece 3. The processing mechanism 5 can be a grinding mechanism or an edge-sealing mechanism, selected according to actual processing requirements. Since both the processing mechanism 5 and the pressure roller 2 are mounted on the integrated mover 10, when the linear motor 1 drives the integrated mover 10 to move to follow the contour changes of the workpiece 3, the relative position between the processing mechanism 5 and the edge of the workpiece 3 remains constant, thus ensuring the consistency of the processing effect. The pressure roller 2 contacts the edge of the workpiece 3 before the processing mechanism 5, which is equivalent to real-time detection of the contour of the workpiece 3, providing a precise position reference for the processing mechanism 5.

[0031] Linear servo driver 7 is electrically connected to linear motor 1 and grating ruler 12, used to control the position of linear motor 1. Rotary servo driver 6 is electrically connected to rotary motor 4 and encoder 41, used to control the speed of rotary motor 4. The servo driver is the core component of the servo system, receiving commands from the host controller and driving the motor to move according to the commands, while simultaneously receiving feedback signals from the encoder to form closed-loop control. Linear servo driver 7 internally implements three-loop control: position loop, speed loop, and current loop, ensuring the positioning accuracy and dynamic response performance of linear motor 1. Rotary servo driver 6 also implements multi-loop control, ensuring smooth speed and accurate angle positioning of rotary motor 4.

[0032] The PLC controller 8 communicates with the linear servo drive 7 and the rotary servo drive 6 via a bus, and receives signals from the encoder 21 and the pressure sensor 22. The PLC controller 8 is the control core of the entire device, responsible for coordinating the movement of each actuator to achieve complex multi-axis synchronous control. The PLC controller 8 preferably communicates with the linear servo drive 7 and the rotary servo drive 6 via an EtherCAT bus 9. EtherCAT is a high-performance industrial Ethernet communication protocol with advantages such as short communication cycles, high synchronization accuracy, and flexible topology. Communication cycles can reach the μs level, making it suitable for high-speed multi-axis synchronous control applications. The PLC controller 8 obtains the position of the linear motor 1 and the angle and speed information of the rotary motor 4 by reading PDO data. PDO is an abbreviation for Process Data Object, a communication object in the EtherCAT protocol used to transmit real-time data, characterized by high transmission efficiency and low latency.

[0033] The PLC controller 8 stores an electronic cam table and a speed planning table. The electronic cam table records the correspondence between the rotation angle of workpiece 3 and the position of linear motor 1, while the speed planning table records the target angular velocity corresponding to different rotation angles of workpiece 3. An electronic cam is a virtual cam mechanism implemented in software. It achieves the correspondence between the master shaft angle and the slave shaft position through a lookup table, offering advantages over mechanical cams such as high flexibility, ease of modification, and no mechanical wear. The PLC controller 8 controls the position of linear motor 1 according to the electronic cam table to follow the rotation angle changes of workpiece 3, and controls the speed of rotary motor 4 according to the speed planning table to maintain a constant pressure and linear velocity of the pressure roller 2 on workpiece 3.

[0034] The present invention also provides an adaptive workpiece machining method using the above-mentioned device, including step S1 workpiece contour recognition and cam table establishment, step S2 speed planning, step S3 normal machining and step S4 adaptive optimization.

[0035] The purpose of step S1, workpiece contour recognition and cam table establishment, is to automatically acquire the contour shape information of workpiece 3 and convert it into an electronic cam table for storage. Traditional machining methods require prior knowledge of the workpiece's precise dimensions and the writing of machining programs. However, this method acquires the workpiece contour through automatic scanning and recognition, eliminating the need for prior knowledge of the workpiece dimensions and reprogramming for different workpieces.

[0036] Step S1 includes sub-step S11 initialization, sub-step S12 low-speed scanning, sub-step S13 constant pressure follow-up, sub-step S14 data acquisition, and sub-step S15 cam table generation.

[0037] The initialization process in sub-step S11 is as follows: The PLC controller 8 sends a position command to the linear servo driver 7, controlling the linear motor 1 to move the pressure roller 2 towards the workpiece 3 at a first speed. This first speed is a relatively fast approach speed, used to quickly shorten the distance between the pressure roller 2 and the workpiece 3, improving efficiency. When the pressure sensor 22 detects a pressure value greater than zero, it indicates that the pressure roller 2 has contacted the edge of the workpiece 3. At this point, the movement switches to a second speed, lower than the first speed, to continue moving. This second speed is a slower approach speed, used to precisely control the contact process and avoid impact caused by excessive speed. During the movement at the second speed, the PLC controller 8 monitors the pressure change rate in real time. The pressure change rate refers to the amount of pressure change per unit time, reflecting the intensity of the contact process. When the pressure value reaches the preset initial contact pressure... The movement stops upon arrival, completing the initial contact positioning. If the pressure change rate exceeds a set threshold during movement, movement stops and an alarm sounds to prevent equipment damage caused by local protrusions or abnormalities at the edge of workpiece 3. A two-stage approach strategy ensures both approach efficiency and the safety and smoothness of the contact process.

[0038] The low-speed scanning process in sub-step S12 is as follows: The PLC controller 8 sends a speed command to the rotary servo driver 6, controlling the rotary motor 4 to drive the workpiece 3 to rotate at a constant speed for one revolution. The purpose of low-speed scanning is to completely acquire the contour data of the workpiece 3 while ensuring the accuracy of pressure control. The selection of scanning speed needs to comprehensively consider the response speed of the pressure control system and the resolution of data acquisition. Too fast a speed will cause the pressure control to lag behind the contour changes, while too slow a speed will reduce production efficiency. The preferred scanning speed range is 3 rpm to 10 rpm, and the specific value can be adjusted according to the complexity of the contour of the workpiece 3 and the performance of the control system.

[0039] The constant pressure follow-up process in sub-step S13 is as follows. During the rotation of workpiece 3, due to the change in the contour of workpiece 3, if linear motor 1 remains stationary, the contact pressure between pressure roller 2 and the edge of workpiece 3 will change with the contour. To maintain a constant contact pressure, linear motor 1 needs to adjust its position in real time to follow the contour change. PLC controller 8 reads the pressure value of pressure sensor 22 at fixed intervals and compares the pressure value with the set value. By comparison, the position adjustment amount of linear motor 1 is calculated using a PID algorithm, and a position adjustment command is sent to linear servo driver 7 to maintain the pressure of pressure roller 2 on workpiece 3 at the set value. Within the allowable deviation range. The PID algorithm is a classic feedback control algorithm, consisting of three control elements: proportional, integral, and derivative. The proportional element responds to the current deviation, the integral element eliminates steady-state error, and the derivative element predicts the deviation trend. The three parameters of the PID algorithm need to be tuned according to the actual system to obtain good dynamic response performance and steady-state accuracy. Pressure setpoint. The allowable deviation range is preferably ±5% of the set value, depending on the material of workpiece 3.

[0040] The data acquisition process in sub-step S14 is as follows: During the rotation of workpiece 3, PLC controller 8 synchronously reads the rotation angle value output by encoder 41. The position value of linear motor 1 output by the grating ruler 12 The data is stored as angle-position pairs. The accuracy of the cam table is determined by the data acquisition cycle and resolution; the more acquisition points, the more accurate the cam table's description of the workpiece's contour. The preferred acquisition method is to acquire data at fixed angular intervals, for example, acquiring one data point every 1°, resulting in 360 data points per cycle. For areas with drastic contour changes, an adaptive acquisition strategy can also be used, increasing the acquisition density in areas with greater curvature.

[0041] The process of generating the cam table in sub-step S15 is as follows: After workpiece 3 rotates one revolution, PLC controller 8 performs spline interpolation on the collected data points to generate a smooth electronic cam table and stores it. Spline interpolation is a numerical analysis method that uses a piecewise polynomial function to fit discrete data points and generate a continuous and smooth curve. Commonly used spline interpolation methods include cubic spline interpolation and B-spline interpolation. Cubic spline interpolation ensures the second-order continuity of the curve, while B-spline interpolation has the advantages of good locality and high computational efficiency. Through spline interpolation, the target position of the corresponding linear motor 1 can be queried at any angle, not just the angle position of the collected points. The electronic cam table uses a function... Stored in the form of , where For rotation angle, This corresponds to the position of linear motor 1.

[0042] The purpose of speed planning in step S2 is to calculate the required rotational angular velocity at each angular position based on the contour shape of workpiece 3, in order to maintain a constant linear velocity of pressure roller 2 relative to the edge of workpiece 3. For non-circular workpieces, if the rotary motor 4 rotates at a constant angular velocity, the linear velocity of each point on the edge of workpiece 3 relative to pressure roller 2 will vary with the change of the equivalent radius, resulting in uneven processing. By speed planning, reducing the angular velocity at positions with a large equivalent radius and increasing the angular velocity at positions with a small equivalent radius, a constant linear velocity can be maintained.

[0043] Step S2 includes sub-step S21 equivalent radius calculation, sub-step S22 angular velocity calculation, and sub-step S23 velocity planning table generation.

[0044] The process of calculating the equivalent radius in sub-step S21 is as follows. The PLC controller 8 reads each angle from the electronic cam table. Corresponding position value The equivalent radius is calculated using the three-point circular arc fitting method. The three-point circular arc fitting method is a geometric calculation method that uniquely determines a circle using three non-collinear points; the radius of this circle is the fitted radius. In practice, three adjacent angle points are selected. , , and their corresponding position values , , Convert the three points to coordinates in a rectangular coordinate system, fit an arc passing through the three points, and the radius of this arc is the angle. Equivalent radius of workpiece profile 3 The method for converting angle-position data pairs to rectangular coordinates utilizes the conversion relationship between polar and rectangular coordinates. , Compared to directly using polar coordinate formulas to calculate the radius of curvature, the three-point circular arc fitting method has advantages such as clear physical meaning, insensitivity to noise, and applicability to arbitrary shape contours.

[0045] The process of calculating the angular velocity in sub-step S22 is as follows. Set the target linear velocity. The PLC controller 8 calculates the required rotational angular velocity for each angular position using the following formula. : ;in, For angle The required rotational angular velocity at that point, measured in rad / s; The target linear velocity is expressed in mm / s. For angle The equivalent radius at that point is in mm. This formula is based on the relationship between linear velocity and angular velocity, i.e. When linear velocity is required When constant, angular velocity With radius Inversely proportional. Target linear velocity The settings are based on the requirements of the processing technology and need to take into account factors such as processing quality, processing efficiency and equipment performance.

[0046] The process of generating the speed planning table in sub-step S23 is as follows. The PLC controller 8 will generate the speed planning table for each angle. With the corresponding angular velocity The speed planning table is constructed and stored. The speed planning table is used in conjunction with the electronic cam table. The electronic cam table is used for position synchronization control, and the speed planning table is used for speed feedforward control. Together, they ensure constant pressure and linear velocity during the machining process.

[0047] Step S3, normal machining, involves actually machining workpiece 3 after contour recognition and speed planning are completed. During normal machining, a combined feedforward and feedback control strategy is employed. The feedforward control performs open-loop control based on pre-planned cam and speed tables, while the feedback control performs closed-loop correction of the feedforward control error. This combination achieves better dynamic performance and steady-state accuracy than simple feedback control.

[0048] Step S3 includes sub-steps S31 (electronic cam synchronization), S32 (angular velocity feedforward), S33 (linear velocity closed loop), and S34 (pressure closed loop).

[0049] The process of electronic cam synchronization in sub-step S31 is as follows: The PLC controller 8 reads the current rotation angle output by encoder 41 in real time. Query the electronic cam table to obtain the target position of the corresponding linear motor 1. The linear servo driver 7 sends position commands to the linear motor 1, causing the position of the linear motor 1 to change synchronously with the rotation angle of the workpiece 3. Electronic cam synchronization is a master-slave synchronous control method, with the rotary motor 4 as the master axis and the linear motor 1 as the slave axis. The position of the slave axis is obtained by mapping the angle of the master axis through a cam table. Electronic cam synchronization control requires high real-time performance, necessitating the completion of angle reading, table lookup interpolation, and position command transmission operations within each control cycle. The control cycle of the PLC controller 8 is preferably no greater than 1ms to ensure the accuracy of the synchronization control.

[0050] The process of sub-step S32 angular velocity feedforward is as follows. The PLC controller 8 calculates the angular velocity feedforward based on the current rotation angle. Query the velocity planning table to obtain the target angular velocity According to system delay time Response time of rotary motor 4 Calculate feedforward time ,in advance Time sends speed commands to the rotary servo drive 6. Feedforward control is an open-loop control method that performs control in advance based on known inputs or disturbances to compensate for system lag. Feedforward time Calculate using the following formula: ; in, This is the feedforward time, measured in seconds (s). This refers to the system communication and processing delay time, measured in seconds (s). Here is the response time constant of the rotating electric motor 4, in seconds. System delay time. This includes communication transmission delay and instruction processing delay, which are related to the bus protocol used and the controller performance. Rotary motor 4 response time constant. This refers to the time it takes for the motor to reach the target speed after receiving a command, and it is related to the motor's mechanical inertia, the bandwidth of the driver, etc. By advancing the time... The timing of the speed command can compensate for the system's lag, synchronizing the actual speed change with the profile change.

[0051] The linear velocity closed-loop process in sub-step S33 is as follows: PLC controller 8 reads the rotational speed of pressure roller 2 output by encoder 21, and calculates the actual linear velocity based on the radius of pressure roller 2. The actual linear velocity With the target linear velocity In comparison, the angular velocity correction amount is calculated using a PI control algorithm. This is superimposed on the speed command of the rotating motor 4. PI control is a simplified form of PID control, omitting the derivative term, and is suitable for applications sensitive to noise or where a fast response is not required. Angular velocity correction amount. Calculate using the following formula: ;in, ; This is the angular velocity correction value, in rad / s; This is the proportional control coefficient; These are integral control coefficients; This represents the linear velocity deviation, in mm / s. The target linear velocity is expressed in mm / s. Actual linear velocity, in mm / s; proportional control coefficient. The integral control coefficient determines the strength of the response to the current deviation. This determines the strength of the response to cumulative deviations. Both coefficients need to be tuned according to the actual system. Excessive size can cause system oscillation. Excessive values ​​can lead to integral saturation. Linear velocity closed-loop control corrects for errors in feedforward control, eliminating linear velocity deviations caused by model errors, parameter variations, and other factors.

[0052] The pressure closed-loop process in sub-step S34 is as follows: The PLC controller 8 reads the pressure value from the pressure sensor 22. If the pressure deviates from the set value... If the position exceeds the allowable range, the position compensation amount of linear motor 1 is calculated and sent to linear servo driver 7 for fine-tuning. The pressure closed loop supplements the electronic cam synchronization control. The electronic cam gauge is generated in step S1, and inaccuracies may occur due to acquisition errors or workpiece 3 installation position deviations. The pressure closed loop can compensate for these errors in real time. The control bandwidth of the pressure closed loop should be lower than that of the electronic cam synchronization to avoid interference between the two control loops.

[0053] The purpose of adaptive optimization in step S4 is to continuously improve the electronic cam table and speed planning table during the machining process, so that the control effect gradually approaches the optimal level. Since the contour recognition in step S1 is performed under low-speed, single-scan conditions, the generated cam table and speed planning table may not be optimal. Adaptive optimization in step S4 can gradually correct the data in these tables and improve control accuracy.

[0054] Step S4 includes sub-step S41 deviation recording, sub-step S42 deviation analysis, sub-step S43 online correction, and sub-step S44 iterative optimization.

[0055] The process of recording the deviation in sub-step S41 is as follows. During the processing in step S3, the PLC controller 8 continuously reads the actual pressure value detected by the pressure sensor 22 and the actual linear velocity calculated by the encoder 21. Calculate the actual pressure and the set value respectively. Deviation and actual linear velocity With the target linear velocity The deviation, and according to the rotation angle Record storage. The deviation data is stored in a triplet format of angle-pressure deviation-linear velocity deviation, corresponding to the angle index of the electronic cam table and speed planning table.

[0056] The deviation analysis process in sub-step S42 is as follows: After workpiece 3 rotates one revolution, PLC controller 8 statistically analyzes the pressure deviation and linear velocity deviation values ​​at each angular position, identifying the angular intervals with larger deviations. Deviation analysis can employ statistical methods, such as calculating the mean and variance of the deviations at each angular position, identifying intervals with larger mean or variance deviations; these intervals are the locations requiring focused correction.

[0057] The online correction process in sub-step S43 is as follows: The PLC controller 8 corrects the position value of the linear motor 1 at the corresponding angular position in the electronic cam table based on the pressure deviation, and corrects the angular velocity value at the corresponding angular position in the speed planning table based on the linear velocity deviation. The principle of correction is to reduce the deviation. If the actual pressure at a certain angular position is greater than the set value, the cam table position value at that angular position should be decreased to make the linear motor 1 move backward; if the actual linear velocity at a certain angular position is less than the target value, the angular velocity value in the speed planning table at that angular position should be increased to increase the speed of the rotary motor 4. The correction amount can be calculated proportionally, and the correction amount is proportional to the deviation. The selection of the proportional coefficient needs to balance convergence speed and stability.

[0058] The iterative optimization process of sub-step S44 is as follows: Repeat steps S3 and S41 to S43. After multiple processing cycles, the electronic cam table and speed planning table gradually converge to the optimal value, completing the adaptive optimization of the control parameters. The convergence condition for iterative optimization can be set as the root mean square value of the deviation being less than a certain threshold, or the deviation change being less than a certain threshold for several consecutive iterations. Adaptive optimization enables the system to have a learning function, automatically adapting to the actual characteristics of workpiece 3 and changes in processing conditions, improving the consistency and stability of processing.

[0059] This invention achieves precise synchronization between the position of linear motor 1 and the rotation angle of workpiece 3 through electronic cam technology, maintains constant linear velocity of pressure roller 2 relative to the edge of workpiece 3 through speed planning, achieves real-time correction of pressure and linear velocity through multi-closed-loop feedback, and improves control parameters online through adaptive optimization. This method is applicable to edge processing of circular, elliptical, polygonal, and arbitrarily irregular shaped workpieces. It eliminates the need for reprogramming or changing fixtures for different workpiece shapes, and the workpiece placement does not require precise positioning; the system can automatically identify and adapt to the actual placement and shape characteristics of the workpiece.

[0060] Example 1 illustrates an application scenario of edge gluing of an elliptical wooden board workpiece, with a major axis of 200mm and a minor axis of 100mm. The device configuration is as follows: Linear motor 1 uses a 300mm stroke linear motor with a positioning accuracy of ±0.01mm; pressure roller 2 has a diameter of 30mm, and encoder 21 has a resolution of 1000 pulses / revolution; pressure sensor 22 has a range of 0 to 100N and an accuracy of 0.5%FS; rotary motor 4 has a rated speed of 3000rpm, and encoder 41 has a resolution of 10000 pulses / revolution; processing mechanism 5 is a gluing mechanism; PLC controller 8 has a control cycle of 1ms and communicates with linear servo driver 7 and rotary servo driver 6 via EtherCAT bus 9. The processing is carried out according to the method of this invention, with the specific steps as follows.

[0061] Step S1: Workpiece contour recognition and cam table establishment. Sub-step S11: Initialization: Set the initial contact pressure F0 to 20N, the first speed to 50mm / s, the second speed to 5mm / s, and the pressure change rate threshold to 100N / s. PLC controller 8 controls linear motor 1 to drive pressure roller 2 towards workpiece 3 at the first speed. When pressure sensor 22 detects a pressure value greater than zero, switch to the second speed. Stop moving when the pressure value reaches 20N. Sub-step S12: Low-speed scanning: Set the scanning speed to 5rpm. Rotary motor 4 drives workpiece 3 to rotate uniformly for one revolution, taking 12s. Sub-step S13: Constant pressure follow-up: PLC controller 8 reads the pressure value at 1ms intervals and uses a PID algorithm to adjust the position of linear motor 1. The PID parameters are Kp=0.5, Ki=0.1, Kd=0.05, and the allowable pressure deviation range is ±5%. Sub-step S14: Data acquisition: Acquire 360 ​​sets of angle-position data pairs at 1° intervals. Sub-step S15 Cam table generation: Electronic cam table is generated using cubic spline interpolation.

[0062] Step S2: Velocity Planning. Sub-step S21: Equivalent Radius Calculation: The equivalent radius at each angular position is calculated using the three-point circular arc fitting method. The equivalent radius at 0° is 50.0 mm, and the equivalent radius at 90° is 200.0 mm. Sub-step S22: Angular Velocity Calculation: The target linear velocity Vt is set to 100 mm / s. The angular velocity is calculated using the formula ωi = Vt / Ri. The angular velocity at 0° is 2.0 rad / s, and the angular velocity at 90° is 0.5 rad / s. Sub-step S23: Velocity Planning Table Generation: The 360 ​​sets of angle-angular velocity data are stored as a velocity planning table, as shown in Table 1.

[0063] Table 1 Speed ​​Planning Table for Example 1

[0064] Table 1 lists the speed planning table for the elliptical workpiece in Example 1. The major axis of the elliptical workpiece is 200 mm, the minor axis is 100 mm, and the target linear velocity Vt is 100 mm / s. The equivalent radius Ri is calculated using the three-point circular arc fitting method, and the target angular velocity ωi is calculated using the formula ωi = Vt / Ri. As can be seen from the table, at angles of 0° and 180°, the minimum equivalent radius is 50.0 mm, and the corresponding maximum target angular velocity is 2.00 rad / s; at angles of 90° and 270°, the maximum equivalent radius is 200.0 mm, and the corresponding minimum target angular velocity is 0.50 rad / s. The angular velocity is inversely proportional to the equivalent radius, ensuring that the linear velocity remains constant throughout the machining process. The speed planning table exhibits a symmetry with a period of 90°, which corresponds to the geometric symmetry of the elliptical profile.

[0065] Step S3: Normal machining. Sub-step S31: Electronic cam synchronization: Using rotary motor 4 as the main shaft and linear motor 1 as the slave shaft, position synchronization is achieved according to the electronic cam table. Sub-step S32: Angular velocity feedforward: The system delay time Td is set to 2ms, the response time Tr of rotary motor 4 is set to 15ms, and the feedforward time Tff is set to 17ms. Sub-step S33: Linear velocity closed loop: PI parameters are Kp=0.02, Ki=0.005. Sub-step S34: Pressure closed loop: The allowable pressure deviation range is ±10%.

[0066] Step S4 Adaptive Optimization. Sub-step S41 Deviation Recording: Record the pressure deviation and linear velocity deviation at each angular position. Sub-step S42 Deviation Analysis: Identify the angular ranges with larger deviations as 85° to 95° and 265° to 275°. Sub-step S43 Online Correction: Correct the cam table position values ​​in the larger deviation ranges with a correction coefficient of 0.3. Sub-step S44 Iterative Optimization: After 5 processing cycles, the deviation converges.

[0067] Example 2 uses the edge grinding of a regular hexagonal metal workpiece as an application scenario. The circumscribed circle diameter of the hexagon is 150mm. The device configuration is the same as in Example 1, except that the processing mechanism 5 is replaced with a grinding mechanism. The initial contact pressure F0 is set to 50N, and the target linear velocity Vt is set to 200mm / s. Processing is performed according to steps S1 to S4. The equivalent radius at the vertex of the hexagon is at least approximately 65mm, and the equivalent radius at the midpoint of the edge is at most approximately 75mm. In the velocity planning table, the angular velocity at the vertex is 3.08rad / s, and the angular velocity at the midpoint of the edge is 2.67rad / s. The deviation converges after 3 processing cycles.

[0068] Example 3 uses edge sealing of irregularly shaped plastic workpieces as an application scenario. The workpiece contour is composed of 4 arc segments and 4 straight segments, with a maximum external dimension of 180mm × 120mm. The device configuration is the same as in Example 1, with processing mechanism 5 being the edge sealing mechanism. The initial contact pressure F0 is set to 15N, and the target linear velocity Vt is set to 80mm / s. Processing is performed according to steps S1 to S4. Due to the irregular contour shape, the equivalent radius varies from 30mm to 120mm, and the angular velocity varies from 0.67rad / s to 2.67rad / s.

[0069] The initial data from the electronic cam meter are as follows: 0° corresponds to a position of 90.0mm, 45° to 70.0mm, 90° to 50.0mm, 135° to 70.0mm, 180° to 90.0mm, 225° to 70.0mm, 270° to 50.0mm, and 315° to 70.0mm. The workpiece contour has drastic curvature changes near the angles of 45°, 135°, 225°, and 315°, where the curves connect to arcs and straight lines.

[0070] The electronic cam meter data after eight adaptive optimizations is as follows: 0° corresponds to a position of 90.0mm, 45° to 70.35mm, 90° to 50.0mm, 135° to 70.35mm, 180° to 90.0mm, 225° to 70.35mm, 270° to 50.0mm, and 315° to 70.35mm. The corrected position values ​​at angles of 45°, 135°, 225°, and 315° were adjusted from 70.0mm to 70.35mm, a correction of 0.35mm, compensating for the acquisition lag error caused by abrupt curvature changes in this area. See Tables 2 and 3 for details.

[0071] Table 2 Initial Electronic Cam Table of Example 3

[0072] Table 3. Optimized electronic cam table for Example 3

[0073] Tables 2 and 3 list the initial electronic cam table and the electronic cam table after 8 adaptive optimizations for the irregularly shaped workpiece in Example 3, respectively. Comparing the two tables, it can be seen that the correction mainly occurs at angles of 45°, 135°, 225°, and 315°, with a correction amount of 0.35 mm for each angle. The position values ​​at angles of 0°, 90°, 180°, and 270° remain unchanged. This is because the contour of the irregularly shaped workpiece consists of four arcs and four straight lines. The connection points between the arcs and straight lines are located near angles of 45°, 135°, 225°, and 315°, where the curvature changes most drastically, resulting in the largest hysteresis error during low-speed scanning. Therefore, a larger correction amount is required. The distribution pattern of the correction amount is closely related to the geometric characteristics of the workpiece contour. The correction amount is largest at the connection points between the arcs and straight lines where the curvature changes drastically, and close to zero in the middle of the straight and arc segments where the curvature changes gently.

[0074] Comparative Example 1 uses the same device configuration and elliptical workpiece as Example 1, but does not perform step S2 speed planning; that is, the rotary motor 4 rotates at a constant angular velocity. The constant angular velocity is set to 1.0 rad / s, and other parameters are the same as in Example 1. Because speed planning is not performed, the linear velocity is 50 mm / s at the equivalent radius of 50 mm at the endpoint of the major axis of the ellipse, and 200 mm / s at the equivalent radius of 200 mm at the endpoint of the minor axis of the ellipse. The linear velocity fluctuates between 50 mm / s and 200 mm / s, with a fluctuation amplitude reaching 300%.

[0075] Comparative Example 2 uses the same device configuration and elliptical workpiece as Example 1, and executes steps S1 to S3, but does not execute step S4 for adaptive optimization. Other parameters are the same as in Example 1. Because adaptive optimization is not performed, the acquisition error caused by the lag in the response of the PID controller during the low-speed scanning phase in the initial electronic cam table cannot be corrected. The pressure deviation is large in the region where the equivalent radius changes drastically, and the deviation does not converge after multiple processing cycles.

[0076] Comparative Example 3 uses the same device configuration and hexagonal workpiece as Example 2, and executes steps S1 to S4. However, in step S3, sub-step S32 (angular velocity feedforward) is not executed; speed control is performed solely by sub-step S33 (linear velocity closed-loop). Other parameters are the same as in Example 2. Because no feedforward control is performed, the linear velocity closed-loop needs to handle all the speed regulation tasks. When the contour curvature changes abruptly at the hexagonal vertex, the closed-loop controller's response lags, resulting in significant overshoot and oscillation in the linear velocity.

[0077] To verify the effectiveness of the method of this invention, the following comparative experiment was designed. The experiment used linear velocity standard deviation, linear velocity fluctuation rate, pressure standard deviation, processing uniformity index, and the number of convergence iterations as evaluation indicators. The linear velocity standard deviation reflects the dispersion of the linear velocity; the smaller the value, the more stable the linear velocity. The linear velocity fluctuation rate is defined as the ratio of the linear velocity range to the target linear velocity, reflecting the relative fluctuation amplitude of the linear velocity. The pressure standard deviation reflects the stability of the contact pressure. The processing uniformity index is defined as the reciprocal of the ratio of the processing thickness standard deviation to the average thickness; the larger the value, the more uniform the processing.

[0078] Experiment 1 compares the linear velocity constancy of Examples 1, 2, and 3 with Comparative Example 1 on workpieces of different shapes. The experimental method is as follows: Elliptical, hexagonal, and irregularly shaped workpieces are processed using the methods of Examples 1, 2, 3, and Comparative Example 1, respectively. The actual linear velocity values ​​at 360 angular positions around the workpiece are recorded, and the standard deviation and fluctuation rate of the linear velocity are calculated. The linear velocity is calculated from the rotational speed and radius of the pressure roller 2 detected by encoder 21, with a sampling period of 1 ms.

[0079] Experimental results are as follows Figure 1 As shown. In Example 1, the standard deviation of the linear velocity for an elliptical workpiece was 2.1 mm / s, with a fluctuation rate of 9.4%; in Example 2, the standard deviation of the linear velocity for a regular hexagonal workpiece was 3.5 mm / s, with a fluctuation rate of 8.2%; in Example 3, the standard deviation of the linear velocity for an irregularly shaped workpiece was 4.8 mm / s, with a fluctuation rate of 12.5%; and in Comparative Example 1, the standard deviation of the linear velocity for an elliptical workpiece was 53.0 mm / s, with a fluctuation rate of 150%. From... Figure 1 It can be seen that the standard deviation and volatility of linear velocity in Examples 1 to 3 using the complete method of this invention are much lower than those in Comparative Example 1, with the volatility of the regular hexagonal workpiece in Example 2 being the lowest. It can be seen that this invention, through speed planning in step S2, adjusts the angular velocity of the rotary motor 4 in real time according to the change in the equivalent radius of the workpiece contour, achieving constant control of the linear velocity of the pressure roller 2 relative to the edge of the workpiece 3. According to kinematic principles, linear velocity v is equal to the product of angular velocity ω and radius r. For non-circular workpieces, when the workpiece rotates at a constant angular velocity, the linear velocity v changes accordingly because the equivalent radius r changes with the angle. This invention calculates the required angular velocity at each angular position using the formula ωi=Vt / Ri, ensuring that Vt remains constant, thereby achieving constant linear velocity. Constant linear velocity is a key factor in ensuring uniform processing quality. Too low a linear velocity will lead to excessively thick adhesive application or excessively deep sanding, while too high a linear velocity will lead to insufficient adhesive application or insufficient sanding. Therefore, speed planning has a direct causal relationship with improving processing uniformity. The volatility of a regular hexagonal workpiece is the lowest because its contour is composed of straight line segments, and the change in the equivalent radius is relatively gentle. The equivalent radius of an elliptical workpiece changes drastically at the endpoint of its major axis, resulting in a slightly higher volatility. The irregularly shaped workpiece has a complex contour and the highest volatility, but it is still within an acceptable range.

[0080] Experimental Example 2 compares the pressure constancy and adaptive optimization convergence characteristics of Example 1 and Comparative Example 2. The experimental method is as follows: The elliptical workpiece is processed for 10 cycles using the methods of Example 1 and Comparative Example 2 respectively. The actual pressure values ​​at 360 angular positions in each cycle are recorded, the standard deviation of the pressure is calculated, and a curve showing the pressure standard deviation changing with the number of iterations is plotted. Simultaneously, the pressure deviation value at an angle of 90° is recorded, and the convergence process of the deviation is analyzed.

[0081] Experimental results are as follows Figure 2 As shown. In Example 1, the standard deviation of pressure in the first cycle was 1.8 N, in the second cycle it was 1.2 N, in the third cycle it was 0.8 N, in the fourth cycle it was 0.6 N, in the fifth cycle it was 0.5 N, and in the sixth to tenth cycles it stabilized at around 0.5 N. In Comparative Example 2, the standard deviations of pressure in each cycle were 1.8 N, 1.85 N, 1.78 N, 1.82 N, 1.80 N, 1.79 N, 1.83 N, 1.81 N, 1.77 N, and 1.82 N, respectively, fluctuating around 1.8 N without a decreasing trend. FromFigure 2 It can be seen that the pressure standard deviation of Example 1 exhibits an exponential decay trend, converging to a steady-state value after approximately the 5th cycle; the pressure standard deviation of Comparative Example 2 fluctuates randomly around the initial value, showing no convergence trend. From the above data, it can be seen that the present invention, through adaptive optimization in step S4, continuously records pressure deviations and performs online correction on the electronic cam gauge, gradually improving the pressure control accuracy and converging to the optimal value. The initial electronic cam gauge is generated during the low-speed scanning phase in step S1. Due to the response lag of the PID controller during the scanning process, when the workpiece contour curvature changes drastically, the actual position of the linear motor 1 lags behind the ideal position, resulting in systematic errors in the collected angle-position data. This error manifests as pressure deviation in the subsequent normal processing phase, and the magnitude and direction of the deviation are related to the rate of change of contour curvature. Sub-step S41 records the deviation by storing the pressure deviation by angle; sub-step S42 analyzes the deviation to identify the angle range with larger deviations; sub-step S43 performs online correction to correct the cam gauge based on the direction and magnitude of the deviation; and sub-step S44 iterative optimization gradually accumulates the correction amount through multiple cycles until it stabilizes. The correction process employs a proportional correction strategy, where the correction amount is proportional to but less than the deviation, avoiding oscillations caused by over-correction. After several iterations, the systematic error in the cam table is gradually eliminated, and the pressure deviation converges to the minimum value determined by random noise. Adaptive optimization enables the system to have self-learning capabilities, automatically compensating for acquisition errors and systematic errors without manual intervention.

[0082] Experiment 3 compares the linear velocity dynamic response performance of Example 2 and Comparative Example 3 in the region of abrupt change in contour curvature. The experimental method is as follows: A regular hexagonal workpiece is machined using the methods of Example 2 and Comparative Example 3, respectively. The actual and target linear velocity values ​​are recorded, focusing on the angle range near the vertex of the hexagon. The overshoot, oscillation amplitude, and settling time of the linear velocity are analyzed. The analysis focuses on the 55° to 65° angle range, which includes one vertex of the hexagon where the contour curvature changes abruptly.

[0083] Experimental results are as follows Figure 3 As shown. At the 60° apex, the target linear velocity abruptly changes from 197.4 mm / s to 205.3 mm / s. In Example 2, the actual linear velocity begins to rise steadily 1° before the apex, reaching 204.1 mm / s at the apex with an overshoot of -0.6%, exhibiting no significant oscillations, and stabilizing near the target value after 0.5°. In Comparative Example 3, the actual linear velocity only begins to respond 2° after the apex, reaching a peak of 218.5 mm / s with an overshoot of 6.4%, followed by three oscillations, stabilizing only after approximately 5°. From Figure 3 It can be seen that the linear velocity curve of Example 2 has a smooth transition, while the linear velocity curve of Comparative Example 3 exhibits obvious hysteresis, overshoot, and oscillation. From Figure 3As can be seen from the diagram, this invention, through sub-step S32 angular velocity feedforward, issues speed commands in advance based on the speed planning table, effectively compensating for system response lag and improving the dynamic response performance of linear velocity. The control system has an inherent delay from receiving the command to completing its execution, including communication delay Td and motor response delay Tr. The communication delay Td is determined by the bus protocol and controller processing speed, while the motor response delay Tr is determined by the motor inertia and driver bandwidth. If pure feedback control is used, correction only begins after the linear velocity deviation occurs, and the correction action requires the aforementioned delay to take effect, resulting in the actual linear velocity lagging behind the target linear velocity. When the contour curvature changes abruptly, the target linear velocity also changes abruptly, causing the feedback controller to generate a large correction amount, easily leading to overshoot and oscillation. Feedforward control predicts the change in target linear velocity based on the speed planning table and issues speed commands in advance by Tff = Td + Tr, synchronizing the change in motor speed with the change in contour curvature, thereby eliminating response lag. The combination of feedforward and feedback control, with feedforward undertaking the main speed regulation task and feedback only needing to correct feedforward errors and random disturbances, results in a fast and stable system response, less prone to overshoot and oscillation. The combined feedforward and feedback control strategy is the key technical means for improving dynamic response performance in this invention.

[0084] Experiment Example 4 analyzes the changes in the electronic cam table and speed planning table of Example 3 before and after adaptive optimization. The experimental method is as follows: An irregularly shaped workpiece is machined using the method of Example 3. The initial electronic cam table and the electronic cam table after 8 rounds of adaptive optimization, as well as the initial speed planning table and the optimized speed planning table, are recorded. The differences between the two at various angular positions are compared. Simultaneously, the distribution law of the correction amount with angle variation is calculated, and the correlation between the correction amount and the contour geometric features is analyzed.

[0085] Experimental results are as follows Figure 4 As shown. Figure 4 It contains two sub-figures: sub-figure (a) is a schematic diagram of the workpiece contour in polar coordinates, showing the corresponding trajectories of the electronic cam table before and after correction; sub-figure (b) shows the curves of position correction and angular velocity correction as a function of angle. From Figure 4It can be seen that the position correction reaches its maximum value of approximately 0.35 mm near angles of 45°, 135°, 225°, and 315°, and approaches zero near angles of 0°, 90°, 180°, and 270°. The distribution pattern of the angular velocity correction is similar to that of the position correction, with a maximum correction of approximately 0.08 rad / s. The contour of the irregularly shaped workpiece consists of four arcs and four straight lines. The connection points between the arcs and the straight lines are located near angles of 45°, 135°, 225°, and 315°, respectively. The curvature changes most drastically at these locations, hence the largest correction values. It can be seen that the adaptive optimization method of this invention can identify and correct errors in the electronic cam table and the speed planning table. The distribution pattern of the correction is closely related to the geometric characteristics of the workpiece contour. During the rapid scanning stage, the pressure closed-loop controller adjusts the position of the linear motor according to the pressure deviation. However, the controller's response speed is limited. When the curvature of the workpiece contour changes rapidly, the linear motor position cannot keep up with the contour change, resulting in a lag error in the acquired position values. The magnitude of the hysteresis error is directly proportional to the rate of curvature change, reaching its maximum at the point of curvature abrupt change. Adaptive optimization gradually eliminates these hysteresis errors through multiple iterations. The positive correlation between the correction amount and the rate of curvature change verifies that adaptive optimization not only corrects the initial acquisition error but also compensates for system drift caused by factors such as mechanical wear and temperature changes after long-term operation, ensuring that the system always maintains optimal performance.

[0086] Experimental Example 5 comprehensively compares the processing quality of all embodiments and comparative examples. The experimental method is as follows: Elliptical, regular hexagonal, and irregularly shaped workpieces were processed using the methods of Examples 1 to 3 and Comparative Examples 1 to 3, respectively. 36 measurement points were selected at equal intervals along the circumference of the workpiece edge to measure the adhesive thickness, edge sealing thickness, or grinding depth, and the processing uniformity index was calculated. Simultaneously, the standard deviation of linear velocity and the standard deviation of pressure were recorded, and grouped bar graphs of the three indicators were plotted for comprehensive comparison.

[0087] Experimental results are as follows Figure 5 As shown. Figure 5 It contains three sub-plots, corresponding to the three evaluation indicators: linear velocity standard deviation, pressure standard deviation, and processing uniformity index. Each sub-plot displays the data from Examples 1 to 3 and Comparative Examples 1 to 3 in the form of a horizontal bar chart. From Figure 5 Subfigure (a) shows that the standard deviation of the linear velocity in Example 1 is 2.1 mm / s, in Example 2 it is 3.5 mm / s, in Example 3 it is 4.8 mm / s, in Comparative Example 1 it is 53.0 mm / s, in Comparative Example 2 it is 2.3 mm / s, and in Comparative Example 3 it is 6.8 mm / s; from Figure 5 Subgraph (b) shows that the pressure standard deviation for Example 1 is 0.5 N, for Example 2 it is 0.8 N, for Example 3 it is 0.7 N, for Comparative Example 1 it is 0.6 N, for Comparative Example 2 it is 1.8 N, and for Comparative Example 3 it is 0.9 N; from Figure 5As shown in sub-figure (c), the processing uniformity index of Example 1 is 28.5, Example 2 is 31.2, Example 3 is 24.8, Comparative Example 1 is 8.3, Comparative Example 2 is 18.6, and Comparative Example 3 is 21.4. These results indicate that Comparative Example 1, lacking speed planning, has a linear velocity standard deviation of 53.0 mm / s, 25 times that of Example 1, resulting in a processing uniformity index of only 8.3, the lowest among all schemes, verifying the decisive role of speed planning in processing quality. Comparative Example 2, lacking adaptive optimization, has a pressure standard deviation of 1.8 N, 3.6 times that of Example 1, causing the processing uniformity index to drop to 18.6, verifying the improvement effect of adaptive optimization on pressure control accuracy. Comparative Example 3, lacking feedforward control, has a linear velocity standard deviation of 6.8 mm / s, 1.9 times that of Example 2, with a processing uniformity index of 21.4, between that of Example 1 and Comparative Example 1, verifying the improvement effect of feedforward control on dynamic response performance. The processing uniformity index of Example 2 reached the highest of 31.2 because the regular hexagonal contour is regular and easy to control; the processing uniformity index of Example 3 was relatively low at 24.8 because the irregular shape contour is complex and difficult to control.

[0088] In summary, this invention achieves position following through electronic cam synchronization, maintains constant linear velocity through speed planning, improves dynamic response through feedforward control, eliminates random errors through closed-loop correction, and eliminates system errors through adaptive optimization, thereby ensuring the uniformity and stability of processing quality.

[0089] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An adaptive workpiece processing device, characterized in that, include: The linear motor (1) includes an integrated mover (10), a guide rail (11) and a grating ruler (12). The integrated mover (10) can move controllably along the guide rail (11), and the grating ruler (12) detects the position of the integrated mover (10). The pressure roller (2) is mounted on the integrated mover (10) and is used to contact the edge of the workpiece (3); the encoder (21) is connected to the pressure roller (2) and is used to detect the rotation speed of the pressure roller (2); the pressure sensor (22) is set on the support structure of the pressure roller (2) and is used to detect the contact pressure between the pressure roller (2) and the edge of the workpiece (3); A rotary motor (4) is connected to the workpiece (3) via a rotating shaft and drives the workpiece (3) to rotate; an encoder (41) is connected to the rotary motor (4) and is used to detect the rotation angle of the workpiece (3); The processing mechanism (5) is installed on the integrated mover (10) and located on the side of the pressure roller (2) to process the edge of the workpiece (3); A linear servo driver (7) is electrically connected to the linear motor (1) and the grating ruler (12) for controlling the position of the linear motor (1); A rotary servo driver (6) is electrically connected to the rotary motor (4) and encoder 2 (41) for controlling the rotational speed of the rotary motor (4); The PLC controller (8) is connected to the linear servo driver (7) and the rotary servo driver (6) via a bus, and receives signals from the encoder (21) and the pressure sensor (22). The PLC controller (8) stores an electronic cam table and a speed planning table. The electronic cam table records the correspondence between the rotation angle of the workpiece (3) and the position of the linear motor (1). The speed planning table records the target angular velocity corresponding to different rotation angles of the workpiece (3). The PLC controller (8) controls the position of the linear motor (1) to follow the rotation angle of the workpiece (3) according to the electronic cam table, and controls the speed of the rotary motor (4) according to the speed planning table, so as to keep the pressure and linear velocity of the pressure roller (2) on the workpiece (3) constant.

2. The apparatus according to claim 1, characterized in that, The PLC controller (8) is connected to the linear servo driver (7) and the rotary servo driver (6) via the EtherCAT bus (9), and obtains the position of the linear motor (1) and the angle and speed information of the rotary motor (4) by reading PDO data.

3. The apparatus according to claim 1, characterized in that, The encoder (21) is mounted on the shaft of the pressure roller (2), and its signal output terminal is connected to the PLC controller (8); the signal output terminal of the pressure sensor (22) is connected to the PLC controller (8) to realize pressure closed-loop control.

4. An adaptive workpiece machining method using the apparatus according to any one of claims 1-3, characterized in that, Includes the following steps: S1. Workpiece contour recognition and cam table establishment: The PLC controller (8) controls the linear motor (1) to move so that the pressure roller (2) contacts the edge of the workpiece (3) to the preset pressure. The rotary motor (4) drives the workpiece (3) to rotate one revolution at low speed. During the rotation, the PLC controller (8) adjusts the position of the linear motor (1) in real time through pressure closed-loop control to keep the contact pressure constant. It records each rotation angle and the corresponding position of the linear motor (1) at the same time and generates an electronic cam table through interpolation algorithm. S2, Speed ​​Planning: The PLC controller (8) calculates the equivalent radius of the workpiece (3) contour at each angular position based on the data of the electronic cam table, and then calculates the required rotational angular velocity at each angular position based on the target linear velocity and the equivalent radius, and generates a speed planning table; S3. Normal processing: The rotary motor (4) is the main shaft and the linear motor (1) is the slave shaft. The PLC controller (8) realizes the synchronous control of the position of the linear motor (1) and the rotation angle of the workpiece (3) according to the electronic cam table. The speed of the rotary motor (4) is fed forward according to the speed planning table. The linear speed of the pressure roller (2) detected by the encoder (21) and the contact pressure detected by the pressure sensor (22) are combined to perform closed-loop correction so that the pressure and linear speed of the pressure roller (2) on the workpiece (3) remain constant during the processing. S4. Adaptive optimization: During the processing in step S3, the PLC controller (8) continuously records the deviation between the actual pressure and the actual linear speed and the set value, and corrects the electronic cam table and speed planning table online to gradually optimize the control parameters.

5. The method according to claim 4, characterized in that, Step S1 includes the following sub-steps: S11. Initialization: The PLC controller (8) sends a position command to the linear servo driver (7) to control the linear motor (1) to drive the pressure roller (2) to move towards the workpiece (3) at the first speed; when the pressure sensor (22) detects that the pressure value is greater than zero, it switches to the second speed, which is lower than the first speed, and continues to move, while monitoring the pressure change rate in real time; when the pressure value reaches the preset initial contact pressure The movement will stop when the pressure change rate exceeds the set threshold during the movement; if the movement rate exceeds the set threshold during the movement, the movement will stop and an alarm will be triggered. S12, Low-speed scanning: The PLC controller (8) sends a speed command to the rotary servo driver (6) to control the rotary motor (4) to drive the workpiece (3) to rotate at a low speed for one revolution. S13, Constant Pressure Follow-up: During the rotation of the workpiece (3), the PLC controller (8) reads the pressure value of the pressure sensor (22) at fixed intervals and compares the pressure value with the set value. By comparison, the position adjustment amount of the linear motor (1) is calculated using a PID algorithm, and a position adjustment command is sent to the linear servo driver (7) to keep the pressure of the pressure roller (2) on the workpiece (3) at the set value. Within the allowable deviation range; S14. Data Acquisition: During the rotation of the workpiece (3), the PLC controller (8) synchronously reads the rotation angle value output by encoder 2 (41). The position value of the linear motor (1) output by the grating ruler (12) Stored as angle-position data pairs; S15, Cam table generation: After the workpiece (3) rotates one revolution, the PLC controller (8) collects the data points. Perform spline interpolation to generate a smooth electronic cam table. And store.

6. The method according to claim 4, characterized in that, Step S2 includes the following sub-steps: S21. Equivalent radius calculation: PLC controller (8) reads each angle from the electronic cam table. Corresponding position value The equivalent radius is calculated using the three-point circular arc fitting method. Take three adjacent angle points , , and their corresponding position values , , Convert the three points to coordinates in a rectangular coordinate system, fit an arc passing through the three points, and the radius of this arc is the angle. The equivalent radius of the contour of the workpiece (3) ; S22, Angular velocity calculation: Set the target linear velocity The PLC controller (8) calculates the required rotational angular velocity for each angular position according to the following formula. : ； in, For angle The required rotational angular velocity at that point, in rad / s; The target linear velocity is expressed in mm / s. For angle The equivalent radius at the location, in mm; S23, Speed ​​planning table generation: PLC controller (8) will generate speed planning table for each angle. With the corresponding angular velocity Create and store the speed planning table.

7. The method according to claim 4, characterized in that, Step S3 includes the following sub-steps: S31, Electronic Cam Synchronization: The PLC controller (8) reads the current rotation angle output by encoder 2 (41) in real time. Query the electronic cam table to obtain the corresponding linear motor (1) target position. Send a position command to the linear servo driver (7) so that the position of the linear motor (1) changes synchronously with the rotation angle of the workpiece (3); S32, Angular velocity feedforward: PLC controller (8) based on the current rotation angle Query the velocity planning table to obtain the target angular velocity According to system delay time Response time of rotating motor (4) Calculate feedforward time ,in advance Time sends speed commands to the rotary servo drive (6); S33, Linear velocity closed loop: The PLC controller (8) reads the rotational speed of the pressure roller (2) output by encoder 1 (21), and calculates the actual linear velocity in combination with the radius of the pressure roller (2). The actual linear velocity With the target linear velocity In comparison, the angular velocity correction amount is calculated using a PI control algorithm. The rotational speed command superimposed on the rotating motor (4); the angular velocity correction amount Calculate using the following formula: ； in, ; This is the angular velocity correction value, and the unit is rad / s; This is the proportional control coefficient; These are integral control coefficients; Linear velocity deviation, in mm / s; The target linear velocity is expressed in mm / s. This refers to the actual linear velocity, in mm / s. S34, Pressure Closed Loop: The PLC controller (8) reads the pressure value from the pressure sensor (22). If the pressure deviates from the set value... If the position exceeds the allowable range, the position compensation amount of the linear motor (1) is calculated and sent to the linear servo driver (7) for fine-tuning.

8. The method according to claim 7, characterized in that, In step S32, the feedforward time Calculate using the following formula: ； in, The feedforward time is expressed in seconds (s). The system communication and processing delay time is measured in seconds (s). The response time constant of the rotating motor (4) is in seconds.

9. The method according to claim 4, characterized in that, Step S4 includes the following sub-steps: S41, Deviation Recording: During the processing in step S3, the PLC controller (8) continuously reads the actual pressure value detected by the pressure sensor (22) and the actual linear velocity calculated by the encoder (21). Calculate the actual pressure and the set value respectively. Deviation and actual linear velocity With the target linear velocity The deviation, and according to the rotation angle Record storage; S42, Deviation Analysis: After the workpiece (3) rotates one revolution, the PLC controller (8) counts the pressure deviation value and linear velocity deviation value at each angular position and identifies the angular range with larger deviation. S43, Online correction: The PLC controller (8) corrects the position value of the linear motor (1) at the corresponding angle position in the electronic cam table according to the pressure deviation, and corrects the angular velocity value at the corresponding angle position in the speed planning table according to the linear velocity deviation. S44. Iterative optimization: Repeat steps S3 and S41-S43. After multiple processing cycles, the electronic cam table and speed planning table gradually converge to the optimal value, completing the adaptive optimization of the control parameters.

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