A method and system for dynamic scheduling of laser engraving tasks

Abstract

This invention discloses a dynamic scheduling method and system for laser engraving tasks, specifically relating to the field of CNC machining control technology for laser engraving. It addresses the shortcomings of existing dynamic scheduling methods in restoring surface engraving tasks, such as neglecting the loss of motion state of the follower control axis and workpiece thermal relaxation deformation, leading to inconsistent machining marks in the continuation area. By recording the breakpoint coordinates, surface contour data, dynamic follower state, and break duration during interruption, and assessing the extent to which the workpiece thermal relaxation deformation exceeds the curvature tolerance domain of the remaining engraving path based on the break duration during restoration, this invention determines whether dynamic state restoration is necessary. If so, it uses the dynamic follower state and surface contour data to assess the margin of error for static startup and generates a guide trajectory. Before laser emission, the follower control axis is controlled to complete dynamic reconstruction along the guide trajectory. After the dynamic tracking state is established, laser emission is initiated to continue executing the remaining engraving instructions from the breakpoint position.

Description

Technical Field

[0001] This invention relates to the field of CNC machining control technology for laser engraving, and more specifically, to a method and system for dynamic scheduling of laser engraving tasks. Background Technology

[0002] In laser engraving production, to adapt to the processing needs of diverse varieties and varying batches, dynamic scheduling can be used to sort and allocate resources for engraving tasks entering the system in real time. For workpieces with curved or non-planar structures, laser engraving equipment is usually equipped with servo control, which can dynamically adjust the relative position of the beam focus and the workpiece surface during engraving to ensure consistency in spot size and energy density. When dealing with emergency orders or abnormal interruptions, dynamic scheduling will preempt the currently executing task and resume the processing of the interrupted task shortly afterward. Upon resumption, existing dynamic scheduling methods, based on the task execution progress and spatial coordinate information recorded before the interruption, reposition the processing head to the breakpoint and continue executing the engraving instructions.

[0003] In existing technologies, dynamic scheduling methods that rely on static position records neglect the problem that the kinematic state of the servo control axis at the moment of interruption is lost due to preemption during the resumption of machining. When the interrupted task is surface engraving, restarting machining from static position coordinates will cause a transient deviation between the actual focus change trajectory of the servo control axis and the preset change trajectory required by the workpiece surface contour. This results in the beam focus being unable to accurately track the surface, causing obvious inconsistencies in machining marks in the continuation area of ​​the interrupted task, affecting machining quality and yield. Summary of the Invention

[0004] In order to overcome the above-mentioned defects of the prior art, the present invention provides a dynamic scheduling method and system for laser engraving tasks to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A method for dynamic scheduling of laser engraving tasks includes the following steps: S1: During the dynamic scheduling of laser engraving, when a preemptive interruption of the curved surface engraving task is triggered, the breakpoint coordinates, curved surface contour data, dynamic following status of the follow-up control axis at the time of interruption, and interruption duration are recorded. S2: When the scheduler resumes the interrupted task, it assesses the extent to which the workpiece thermal relaxation deformation exceeds the curvature tolerance domain of the remaining engraving path based on the duration of the interruption, and determines whether the follow-up control axis needs to perform dynamic state recovery. S3: If dynamic state recovery is required, the dynamic following state and surface profile data are used to evaluate the margin of the initial following error relative to the machining tolerance when directly following the remaining path in a stationary state, and the margin is used to generate a guide trajectory that enables the dynamic response of the follower control axis to be synchronously reconstructed with the surface profile. S4: Position the processing head to the breakpoint coordinates and control the follow-up control axis to run along the guide trajectory before the laser beam is emitted; S5: After the follow-up control axis completes the guide trajectory and establishes the dynamic tracking state, the laser output is turned on to continue executing the remaining engraving instructions from the breakpoint position.

[0006] Furthermore, S1 includes: When the preemptive interrupt is triggered, the speed feedforward and position following error output by the servo drive of the follow-up control axis are read, combined into a dynamic following state and saved. Start a timing process to record the time elapsed from the generation of the preemptive interrupt instruction to the arrival of the scheduling recovery instruction, and obtain the interrupt duration; The current command position is obtained from the CNC system as the breakpoint position coordinates. The surface contour data corresponding to the interrupted task is retrieved from the task file. The breakpoint position coordinates are mapped to the corresponding trajectory nodes in the surface contour data and then the surface contour data is saved.

[0007] Furthermore, S2 includes: When the scheduler resumes the interrupted task, the coordinates of the breakpoint are mapped to the surface contour data, the remaining carving path from the breakpoint to the carving end point is determined, and the curvature tolerance domain of each point on the remaining carving path is extracted from the surface contour data. Based on the duration of the interruption and the thermal relaxation characteristics of the workpiece material, the thermal relaxation deformation generated by the workpiece during the interruption is obtained. By comparing the thermal relaxation deformation with the curvature tolerance domain, the degree of excess is obtained; If the degree exceeds the limit, it indicates that the thermal relaxation deformation has exceeded the curvature tolerance range, and it is determined that the follower control axis needs to perform dynamic state recovery.

[0008] Furthermore, based on the duration of the interruption and the thermal relaxation characteristics of the workpiece material, the thermal relaxation deformation is obtained, including: Extract the workpiece material type from the task file of the interrupted task, and call the corresponding thermal time constant and thermal expansion coefficient according to the workpiece material type; The duration of the interruption is compared with the thermal time constant to determine the thermal relaxation stage of the workpiece during the interruption. Based on the thermal relaxation stage and the coefficient of thermal expansion, the contour deformation displacement of the workpiece caused by the temperature gradient decay from the interruption time to the recovery time is calculated as the thermal relaxation deformation.

[0009] Furthermore, S3 includes: If dynamic state recovery is required, analyze the dynamic following state to obtain the speed feedforward and position following error of the follow-up control axis at the time of interruption. The direction and rate of curvature change of the remaining carving path at the breakpoint are determined using surface contour data; Assuming that the following is started directly from a stationary state, the initial following error is obtained based on the velocity feedforward and the rate of change of curvature. Obtain the processing tolerance range corresponding to the interrupted task, and compare the initial following error with the processing tolerance range to obtain the excess margin; Using the excess margin as the acceleration amplitude adjustment amount for the guide trajectory, a guide trajectory is generated along the curvature change direction to transition the follower control axis from rest to synchronization with the surface profile.

[0010] Furthermore, obtaining excess margin includes: The ratio of the initial following error to the allowable processing range is calculated. When the ratio is greater than the preset judgment threshold, the ratio will be converted into an excess margin. Among them, the excess margin characterizes the order of magnitude of the initial following error exceeding the allowable range of the processing when the following is directly started in a static state.

[0011] Furthermore, S4 includes: Drive the machining head from its current position to the machining breakpoint at the time of the interruption, according to the breakpoint coordinates. Before the laser beam emission command is triggered, the acceleration and position commands arranged sequentially in the guide trajectory are sent to the follow-up control axis point by point; The follower control axis performs accelerated motion along the guide trajectory and reaches a dynamic response state synchronized with the surface profile at the end of the guide trajectory.

[0012] Furthermore, controlling the follow-up control axis to run along the guide trajectory includes: The servo control axis is driven to accelerate from zero speed according to the acceleration commands arranged in sequence in the guide trajectory; The actual position following error of the servo control axis is detected synchronously during acceleration. When the actual position following error is consistent with the expected following error at the corresponding moment in the guide trajectory, it is determined that the follow-up control axis has reached the dynamic response state synchronized with the surface contour, and the remaining position commands in the guide trajectory are executed as synchronous following commands.

[0013] Furthermore, S5 includes: Detect whether the follow-up control axis has reached the end point of the guide trajectory and has established a dynamic tracking state synchronized with the surface profile; When the endpoint of the guide trajectory is detected and a dynamic tracking state has been established, the laser emission command is immediately triggered. Starting from the starting point of the remaining engraving instructions corresponding to the breakpoint coordinates, the remaining engraving instruction sequence is retrieved from the CNC task file and sent line by line to the execution unit to continue the surface engraving process of the interrupted task.

[0014] On the other hand, the present invention provides a dynamic scheduling system for laser engraving tasks, comprising the following modules: The information recording module is used to record the breakpoint coordinates, surface contour data, dynamic following status of the follow-up control axis at the moment of interruption, and duration of interruption when a preemptive interruption of the curved surface engraving task is triggered during the dynamic scheduling of laser engraving. The status judgment module is used to assess the extent to which the workpiece thermal relaxation deformation exceeds the curvature tolerance domain of the remaining engraving path based on the duration of the interruption when the scheduling resumes the interrupted task, and to determine whether the follow-up control axis needs to perform dynamic status recovery. The trajectory generation module is used to evaluate the margin of the initial following error relative to the machining tolerance when directly following the remaining path in a stationary state using dynamic following state and surface profile data if dynamic state recovery is required, and to generate a guide trajectory based on the margin to enable the dynamic response of the follower control axis to be synchronously reconstructed with the surface profile. The operation control module is used to position the processing head to the breakpoint coordinates and control the follow-up control axis to run along the guide trajectory before the laser beam is emitted; The instruction execution module is used to start laser light output and continue executing the remaining engraving instructions from the breakpoint position after the follow-up control axis completes the guide trajectory and establishes a dynamic tracking state.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. By synchronously recording the dynamic following state and interrupt duration of the servo control axis when the preemptive interruption is triggered by dynamic scheduling, the decision-making basis during recovery is no longer limited to the static position, but fully retains the kinematic characteristics and time information at the moment of interruption. Based on the interruption duration, the relationship between the workpiece thermal relaxation deformation and the curvature tolerance domain of the remaining engraving path is evaluated, which can effectively determine the situation where simple position recovery cannot meet the processing accuracy. Thus, at the scheduling level, the timing of dynamic state recovery is actively identified, avoiding the hidden quality defects caused by forced static engraving under the influence of thermal deformation, and ensuring the process stability of laser engraving under dynamic scheduling interference.

[0016] 2. When dynamic state recovery is required, the recorded dynamic following state and surface contour data are used to assess the margin of the initial following error caused by static start-up relative to the allowable processing range. Based on this margin, a guide trajectory is generated. Before the laser beam is emitted, the servo control axis is controlled to complete the dynamic reconstruction process from static to synchronize with the surface contour. This ensures that the focus motion trajectory at the moment of reconnection matches the surface change law, eliminating transient deviations caused by loss of motion state. As a result, the continuous consistency of surface engraving marks is achieved after intermittent processing, improving the processing quality and yield of laser engraving in dynamic scheduling scenarios. Attached Figure Description

[0017] Figure 1 This is a flowchart of a dynamic scheduling method for laser engraving tasks according to the present invention; Figure 2 This is a schematic diagram of the structure of a dynamic scheduling system for laser engraving tasks according to the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] Example 1: Figure 1 This invention provides a dynamic scheduling method for laser engraving tasks, which includes the following steps: S1: During the dynamic scheduling of laser engraving, when a preemptive interruption of the curved surface engraving task is triggered, the breakpoint coordinates, curved surface contour data, dynamic following status of the follow-up control axis at the time of interruption, and interruption duration are recorded. S2: When the scheduler resumes the interrupted task, it assesses the extent to which the workpiece thermal relaxation deformation exceeds the curvature tolerance domain of the remaining engraving path based on the duration of the interruption, and determines whether the follow-up control axis needs to perform dynamic state recovery. S3: If dynamic state recovery is required, the dynamic following state and surface profile data are used to evaluate the margin of the initial following error relative to the machining tolerance when directly following the remaining path in a stationary state, and the margin is used to generate a guide trajectory that enables the dynamic response of the follower control axis to be synchronously reconstructed with the surface profile. S4: Position the processing head to the breakpoint coordinates and control the follow-up control axis to run along the guide trajectory before the laser beam is emitted; S5: After the follow-up control axis completes the guide trajectory and establishes the dynamic tracking state, the laser output is turned on to continue executing the remaining engraving instructions from the breakpoint position.

[0020] A dynamic scheduling method for laser engraving tasks, wherein step S1 further includes: When a preemptive interrupt is triggered, the current velocity feedforward is read from the data output interface of the servo drive of the follow-up control axis, and the current position following error is read from the following error register of the same servo drive. The velocity feedforward is the velocity control component pre-output by the servo drive to compensate for curvature changes when executing surface engraving commands. The position following error is the instantaneous position difference between the actual position and the commanded position of the follow-up control axis. The reading of the velocity feedforward and the position following error is completed within the same control cycle generated by the preemptive interrupt command via the internal data bus of the CNC system. The timing of this control cycle is triggered by the interrupt signal of the CNC system. After the interrupt signal is triggered, the CNC system sends a freeze command to the servo drive. After receiving the freeze command, the servo drive latches the velocity feedforward value of the current cycle in the data output interface and the position following error value in the following error register. The latched velocity feedforward value is read from the data output interface, and the latched position following error value is read from the following error register. The read speed feedforward value and position following error value are combined according to a predefined data format. During combination, the speed feedforward value is placed before the data field, and the position following error value is placed after the data field. The combined data is then saved as a dynamic following state to the static random access memory (SRAM) of the CNC system. When saving the dynamic following state, a corresponding identifier field is created. This identifier field contains the unique task number of the interrupted task, the trigger timestamp of the preemptive interrupt instruction, and a pointer to the starting address of the dynamic following state in the SRAM. This ensures that in subsequent steps, when the interrupted task is resumed, the CNC system can retrieve the corresponding dynamic following state from the SRAM based on the unique task number and the trigger timestamp of the preemptive interrupt instruction. This retrieval process matches the task number field in the identifier field with the unique task number of the currently resumed task, and simultaneously matches the trigger timestamp in the identifier field with the trigger timestamp of the interrupt event corresponding to the currently resumed task. When both matching conditions are met, the complete dynamic following state data is read from the storage area pointed to by the starting address pointer.

[0021] Simultaneously with the interrupt trigger, a timing process is initiated internally within the CNC system. The timing process is started when the interrupt command is triggered by a falling edge signal from the task scheduling module. Upon detecting the falling edge signal, the CNC system sends a reset command to the timer, setting its current count to zero. Then, it sends a start command to the timer, initiating the count of the control cycle. The timer's counting frequency is synchronized with the CNC system's control cycle; that is, the timer's count increments once after each control cycle is completed. Each increment represents a unit of time equal to the duration of one control cycle. The duration of the control cycle is preset by the CNC system's control cycle parameters. For example, if the control cycle is 1 millisecond, each increment represents 1 millisecond of elapsed time. When the interrupted task's resumption command arrives at the CNC system, this event serves as the stop trigger signal for the timing process. Upon detecting the stop trigger signal, the CNC system immediately reads the timer's current count and sends a stop command to stop the timer's accumulation. The read count value is sent to the duration conversion unit. The duration conversion unit multiplies the count value by the duration of the control cycle to calculate the time elapsed from the generation of the preemptive interrupt instruction to the arrival of the scheduling recovery instruction, expressed in actual physical time units. The calculated time is saved as the interrupt duration. When saving the interrupt duration, the start and end timestamps of the interrupt duration are recorded. The start timestamp is the trigger time of the preemptive interrupt instruction, and the end timestamp is the arrival time of the scheduling recovery instruction. The start and end timestamps are stored together with the interrupt duration. Subsequent steps use the start and end timestamps to determine the precise boundaries of the interrupt time span when evaluating thermal relaxation deformation.

[0022] When obtaining the current instruction position from the CNC system as the breakpoint coordinates, the CNC system's instruction position register stores the target endpoint coordinates of the currently executing CNC instruction line. During a preemptive interrupt, if the CNC system interrupts before fully executing the current instruction line, the value in the instruction position register will be the endpoint coordinates of the most recently fully executed instruction line. The position read function is called to read this endpoint coordinate value from the instruction position register. This read coordinate value is used as the breakpoint coordinates. The breakpoint coordinates contain position components in multiple directions; for example, in a 3D machining scene, the breakpoint coordinates contain position components in three translational directions. The breakpoint coordinates are written into a preset breakpoint information structure, which centrally stores all information elements related to the breakpoint of the interrupted task. Simultaneously with writing the breakpoint coordinates, the coordinate system identifier is recorded. This identifier records the position reference system of the machining head at the time of the interruption; for example, the coordinate system identifier can be a coordinate value identifier in the workpiece coordinate system or a coordinate value identifier in the machine tool coordinate system. Simultaneously, the surface contour data corresponding to the interrupted task is retrieved from the task file. The task file is stored in the file storage area of ​​the CNC system and has been fully loaded into the running memory by the task parsing module before the interrupted task begins machining. The surface contour data is searched and retrieved in the running memory based on the unique task number of the interrupted task. The surface contour data contains the coordinate sequence of each point on the machining path and the corresponding normal vector sequence. The coordinate sequence describes the spatial geometry of the surface engraving contour, and the normal vector sequence describes the surface normal at each point. The process of mapping the breakpoint position coordinates to the corresponding trajectory node in the surface contour data is as follows: In the coordinate sequence of the surface contour data, using the Euclidean distance between each point and the breakpoint position coordinates as a metric, the point that coincides with the breakpoint position coordinates within the allowable error range is found from the coordinate sequence. This point is the trajectory node corresponding to the breakpoint position coordinates. The allowable error range is preset according to the machining accuracy requirements, for example, the allowable error range is set to half the distance between two adjacent sampling points in the surface contour data. When there is no sampling point in the coordinate sequence that coincides with the breakpoint location coordinates within the allowable error range, the first unprocessed sampling point in the coordinate sequence that is immediately adjacent to the breakpoint location coordinates and located after the breakpoint is selected as the trajectory node, and this unprocessed sampling point is used as the starting node of the remaining carving path.

[0023] After mapping the trajectory nodes, the surface contour data is truncated and saved. During truncation and saving, starting from the trajectory node, a continuous coordinate subsequence is extracted from the complete surface contour data corresponding to the interrupted task, extending from the trajectory node to the last coordinate point in the surface contour data. Simultaneously, the corresponding normal vector subsequence is extracted. The extracted continuous coordinate subsequence is used as the geometric data of the remaining carving path, and the extracted normal vector subsequence is used as the normal data of the remaining carving path. The geometric data and normal data of the remaining carving path are stored together in the static random access memory of the CNC system, along with the unique task number of the interrupted task and the node index of the trajectory node in the surface contour data. In step S2, when the scheduler resumes the interrupted task, it directly retrieves the surface contour data of the remaining carving path from the static random access memory based on the unique task number and node index of the interrupted task. Based on the surface contour data, it determines the remaining carving path from the breakpoint to the carving end point. Then, it extracts the curvature tolerance domain corresponding to each point on the remaining carving path, so that subsequent steps do not need to re-traverse the original task file.

[0024] A dynamic scheduling method for laser engraving tasks, wherein step S2 further includes: When resuming an interrupted task, the breakpoint coordinates saved in S1 are mapped to the surface contour data extracted and saved in S1 to determine the remaining carving path from the breakpoint to the carving endpoint. The mapping process directly utilizes the established correspondence between breakpoint coordinates and trajectory nodes in S1. From the surface contour data, the coordinates corresponding to the trajectory nodes are used as the starting point of the remaining carving path, and the last coordinate point in the surface contour data is used as the ending point. The continuous subsequence of coordinates between the starting and ending points is determined as the remaining carving path. After determining the remaining carving path, the curvature tolerance domain of each sampling point on the remaining carving path is extracted from the surface contour data. The curvature tolerance domain at any point on the surface is defined as the maximum allowable geometric deviation range along the surface normal direction at that point. Within this range, the positional shift of the laser focus relative to the workpiece surface will not cause the carving quality to deteriorate to an unacceptable level. The method for extracting the curvature tolerance domain is as follows: For each sampling point on the remaining carving path, based on the normal vector of the sampling point in the surface contour data, take a segment in the normal direction of the sampling point with the sampling point as the center of symmetry. The half length of this segment is equal to the projection length of the processing tolerance range in the normal direction. The processing tolerance range is obtained from the task parameters of the interrupted task. The task parameters define the upper limit of the allowable focus position deviation for different carving areas. For example, the upper limit is set to 5 micrometers in the fine carving area and 15 micrometers in the rough carving area. This upper limit is directly used as the projection length of the processing tolerance range in the normal direction.

[0025] By utilizing the interruption duration recorded in S1 and combining it with the workpiece material thermal relaxation characteristics extracted from the task file of the interrupted task, the thermal relaxation deformation of the workpiece during the interruption is obtained. First, the workpiece material type is extracted from the task file of the interrupted task. The task file is loaded and parsed by the CNC system before the interrupted task begins processing. The workpiece material type is stored as an encoded string in the material attribute field of the task file; the workpiece material type is obtained directly by reading the material attribute field. Based on the workpiece material type, the corresponding thermal time constant and coefficient of thermal expansion are retrieved from the preset material thermal property database. The material thermal property database is stored in the non-volatile storage area of ​​the CNC system. Each material record in the database contains a material code field, a thermal time constant field, and a coefficient of thermal expansion field. The unit of the thermal time constant is seconds, and the unit of the coefficient of thermal expansion is per Kelvin. The thermal time constants of each record in the material thermal property database were pre-obtained through material temperature decay experiments under laser irradiation conditions. The time taken for the temperature to drop from the initial peak value to approximately 37% of the initial peak value was taken as the value of the thermal time constant. The coefficient of thermal expansion was taken as the average of the linear coefficients of thermal expansion for the corresponding temperature range from the material physics handbook. Next, the duration of the interruption was compared with the thermal time constant, and the thermal relaxation stage of the workpiece during the interruption was determined based on the comparison results. The rules for dividing the thermal relaxation stage are as follows: when the duration of the interruption is less than the thermal time constant, it is determined to be a rapid cooling stage; when the duration of the interruption is greater than or equal to the thermal time constant but less than 3 times the thermal time constant, it is determined to be a transitional cooling stage; when the duration of the interruption is greater than or equal to 3 times the thermal time constant, it is determined to be a basic cooling stage. The selection of 3 times the thermal time constant is based on the fact that after the exponential decay function has experienced 3 times the time constant, the temperature has decayed to approximately 5% of the initial peak value, and the thermal effect is close to disappearing. After determining the thermal relaxation stage, the contour deformation displacement of the workpiece from the interruption time to the recovery time due to the attenuation of the temperature gradient is calculated based on the thermal relaxation stage and the coefficient of thermal expansion. The obtained contour deformation displacement is the thermal relaxation deformation. When calculating the contour deformation displacement, the trigger time stamp of the preemptive interruption command is read from the breakpoint information structure recorded in S1 as the interruption time, and the termination time stamp recorded in S1 is used as the recovery time. The temperature gradient distribution around the carving point at the interruption time is used as the initial temperature field condition. The attenuation of the temperature gradient inside the material follows an exponential law with the thermal time constant as the characteristic time. During the rapid cooling stage, the temperature gradient attenuation is large. The contour deformation displacement is estimated by multiplying the initial normal temperature rise by the coefficient of thermal expansion and then by a correction coefficient related to the ratio of the interruption duration to the thermal time constant. The correction coefficient is obtained by substituting the ratio of the interruption duration to the thermal time constant into the exponential compensation function. The specific form of the exponential compensation function is stored in the algorithm parameter table of the CNC system. During the transition cooling phase, the profile deformation displacement is calculated by integrating the temperature decay function over the duration of the interruption and multiplying the integral result by the coefficient of thermal expansion to obtain the profile deformation displacement.During the basic cooling stage, the temperature gradient has basically disappeared, and the residual profile deformation displacement tends to stabilize. The pre-stored residual deformation displacement corresponding to the material type of the workpiece is directly retrieved from the material thermal property database as the thermal relaxation deformation. The pre-stored residual deformation displacement is obtained by measuring the same material under the same laser processing parameters through interrupted cooling experiments, and its value is written into the material thermal property database as a fixed value.

[0026] After obtaining the thermal relaxation variable, it is compared with the curvature tolerance domain of each sampling point on the remaining carving path to determine the degree of exceedance. The comparison process is as follows: traverse each sampling point on the remaining carving path sequentially. For each sampling point, compare the projected length of the thermal relaxation variable in the normal direction of that sampling point with half the length of the curvature tolerance domain corresponding to that sampling point. The half length of the curvature tolerance domain is equal to the projected length of the processing allowable range in the normal direction of that sampling point. If the projected length of the thermal relaxation variable in the normal direction of the sampling point is greater than half the length of the curvature tolerance domain, an exceedance marker is recorded. After the traversal is complete, if the number of sampling points with exceedance markers is greater than zero, the degree of exceedance is determined to be that the thermal relaxation variable has exceeded the curvature tolerance domain; if the number of sampling points with exceedance markers is equal to zero, the degree of exceedance is determined to be that the thermal relaxation variable has not exceeded the curvature tolerance domain. The projection length of the thermally relaxed deformation in the normal direction is calculated by multiplying the scalar value of the thermally relaxed deformation by the magnitude of the normal vector of the sampling point. Since the normal vector is defined as a unit vector at this time, the result of the multiplication operation is the projection length of the thermally relaxed deformation in the normal direction.

[0027] The system determines whether dynamic state recovery is required for the servo control axis based on the degree of exceedance. If the degree of exceedance is determined to be such that the thermal relaxation deformation has exceeded the curvature tolerance range, dynamic state recovery is required for the servo control axis, and the guide trajectory generation process begins in step S3 based on this determination. If the degree of exceedance is determined to be such that the thermal relaxation deformation has not exceeded the curvature tolerance range, dynamic state recovery is not required for the servo control axis. The machining head is directly positioned to the breakpoint coordinates using the conventional breakpoint continuation carving method, and the laser output is activated to execute the remaining carving instructions after positioning is completed.

[0028] A dynamic scheduling method for laser engraving tasks, wherein step S3 further includes: When step S2 determines that the servo control axis needs to perform dynamic state recovery, the CNC system enters the processing flow of step S3. The dynamic following state stored in S1 is parsed. In S1, the dynamic following state is stored as a concatenated data field containing a speed feedforward value and a position following error value. In S3, the CNC system splits the dynamic following state in the reverse order of concatenation. The speed feedforward value is read from the beginning of the data field, and the position following error value is read from the end of the data field, thus obtaining the speed feedforward and position following error of the servo control axis at the moment of interruption. The speed feedforward is the speed control amount pre-applied to the servo driver by the servo control axis to compensate for changes in surface curvature during interruption. The value of the speed feedforward is latched by the servo driver at the data output interface at the moment of interruption. The position following error is the instantaneous position difference between the actual position and the commanded position of the servo control axis at the moment of interruption, latched by the following error register at the moment of interruption. The velocity feedforward value obtained from the decomposition is stored in the first variable, and the position following error value is stored in the second variable, so that they can be called separately when calculating the initial following error later.

[0029] The curvature change direction and rate of curvature change of the remaining carving path at the breakpoint are determined using the surface contour data extracted and saved in S1. The determination method is as follows: In the continuous coordinate subsequence of the surface contour data, the trajectory node is used as the starting point of the remaining carving path. A local path segment is formed by taking the trajectory node and several adjacent consecutive sampling points. For example, a local path segment is formed by taking the trajectory node and two adjacent sampling points (a total of three points). Spatial curve fitting is performed on the coordinates of the sampling points in the local path segment. The fitting method uses a geometric method of determining a spatial arc by three points. The spatial coordinates of the three sampling points in the local path segment are substituted into the arc fitting process to solve for the center position and radius of the spatial arc passing through these three sampling points. The reciprocal of the arc radius is used as the rate of curvature change of the remaining carving path at the breakpoint, and the projection direction of the unit direction vector from the trajectory node to the center onto the normal direction of the trajectory node is used as the curvature change direction of the remaining carving path at the breakpoint. The direction of curvature change indicates the orientation of the surface profile's curvature at the breakpoint, while the rate of curvature change indicates the severity of the curvature at the breakpoint. When the sampling points in a local path segment are approximately collinear and cannot fit an effective circular arc, the rate of curvature change is zero, and the direction of curvature change is taken as the default direction of the normal vector at the trajectory node.

[0030] Assuming direct initiation of tracking from a stationary state, the initial tracking error is obtained based on the velocity feedforward and the rate of curvature change. When tracking is initiated directly from a stationary state, the velocity of the servo control axis is established from zero. However, the curvature change of the surface contour at the breakpoint requires the servo control axis to move at a certain velocity along the direction of curvature change to maintain focus tracking, resulting in a transient mismatch. The initial tracking error is obtained by multiplying the rate of curvature change by the reciprocal of a gain coefficient related to the servo response characteristics of the servo control axis. This yields the initial command velocity required for the servo control axis to follow the curvature change of the surface. The gain coefficient is read from the parameter table of the servo driver of the servo control axis, and its physical meaning is the ratio between the command velocity and the actual response velocity. The initial command velocity is compared with the velocity feedforward, and the difference is taken. This difference is then multiplied by the servo lag time of the servo control axis in a stationary state. The product is the initial tracking error. The servo lag time is obtained from the parameters of the servo drive of the servo axis and represents the inherent time delay between the received command and the actual output response of the servo axis. The value of the servo lag time is, for example, 2 milliseconds. The speed feedforward is used as a reference in the calculation of the initial following error. When the speed feedforward is large, the difference between the initial command speed caused by starting from zero speed and the speed feedforward is more significant, and the initial following error increases accordingly.

[0031] The process involves obtaining the allowable machining range corresponding to the interrupted task and comparing the initial following error with the allowable machining range to determine the excess margin. The allowable machining range is obtained from the task parameters of the interrupted task. These parameters define the upper limit of the allowed focal position deviation for different engraving areas, and this upper limit is stored in the allowable machining range field. The allowable machining range is read from this field; its dimension is length, for example, 5 micrometers in a fine engraving area. The excess margin is determined by dividing the absolute value of the initial following error by the allowable machining range to obtain a dimensionless ratio. This ratio is then compared with a preset judgment threshold, which is read from the CNC system's algorithm parameter table. The preset judgment threshold is set based on the condition that when the ratio of the initial following error to the allowable machining range is 1, the initial following error is exactly equal to the allowable machining range, indicating a critical state; therefore, the preset judgment threshold is set to 1. When the ratio is greater than the preset threshold 1, the initial following error has exceeded the allowable processing range. The ratio is then converted into an excess margin, calculated as the excess margin equal to the ratio minus the preset threshold 1. The excess margin is numerically represented by the order of magnitude by which the initial following error exceeds the allowable processing range when following is directly initiated from a stationary state. The larger the excess margin, the more severe the degree to which the initial following error exceeds the allowable processing range. When the ratio is less than or equal to the preset threshold 1, the excess margin is zero, indicating that the initial following error has not exceeded the allowable processing range.

[0032] Using an excess margin as the acceleration amplitude adjustment amount for the guide trajectory, a guide trajectory is generated along the curvature change direction to transition the servo control axis from rest to synchronization with the surface contour. When generating the guide trajectory, it is constructed as a spatial curve that accelerates in the curvature change direction. The starting point of the spatial curve corresponds to the stationary position of the servo control axis at the moment of interruption, and the ending point corresponds to the position and velocity state required for the servo control axis to achieve synchronization with the surface contour. The excess margin, as the acceleration amplitude adjustment amount, is used to adjust the magnitude of the acceleration in the guide trajectory. The larger the excess margin, the larger the acceleration amplitude in the guide trajectory, and the higher the degree of matching between the final velocity reached by the servo control axis at the end of the guide trajectory and the required following velocity of the surface contour. The guide trajectory is generated as follows: a displacement segment is taken along the direction of curvature change. The length of this displacement segment is determined by both the position following error and the rate of curvature change. Specifically, it is the absolute value of the position following error divided by the rate of curvature change, multiplied by an adjustment coefficient. The adjustment coefficient is retrieved from the algorithm parameter table of the CNC system. The principle for setting the adjustment coefficient is to ensure that the actual position following error of the servo control axis at the end of the guide trajectory recedes to within the allowable machining range. For example, the adjustment coefficient is set to 1.2. The time history of this displacement segment is discretized according to the acceleration motion law. The acceleration motion law adopts a uniform acceleration motion mode. Under the uniform acceleration motion mode, the acceleration in the guide trajectory is a constant value, which is equal to the excess margin multiplied by a reference acceleration. The reference acceleration is set according to the maximum acceleration capability of the servo drive of the servo control axis. The reference acceleration value is read from the servo drive parameters, for example, a reference acceleration of 5 meters per square second. The control cycle used during discretization is the same as that of the CNC system. At each discrete time point, the position coordinates and velocity values ​​that the servo control axis should achieve in the guide trajectory are calculated. The position coordinates and velocity values ​​at each discrete time point are arranged sequentially to form a guide trajectory data sequence containing acceleration and position commands. The acceleration command is the acceleration value at each discrete time point in the guide trajectory, and the position command is the position coordinate at each discrete time point in the guide trajectory. The generated guide trajectory data sequence is stored in the static random access memory of the CNC system, with a unique identifier for the guide trajectory and the generation timestamp of step S3 attached during storage, so that step S4 can directly retrieve it when needed.

[0033] A dynamic scheduling method for laser engraving tasks, wherein step S4 further includes: After generating and storing the guide trajectory in step S3, the CNC system proceeds to step S4, positioning the machining head to the breakpoint coordinates. The breakpoint coordinates are read from the breakpoint information structure saved in S1, and used as the target position the machining head needs to move to. The current position coordinates of the machining head are read from the CNC system's position register, used as the starting point and the breakpoint coordinates as the ending point. A no-travel path is planned between the starting and ending points. The planning principle for the no-travel path is to avoid interference with the surface of the machined workpiece. The no-travel path is divided into a rapid traverse segment and a slow approach segment. The rapid traverse segment moves the machining head from its current position above the safety height to a safe position directly above the breakpoint coordinates. The safety height parameter is stored in the CNC system's machining parameter table. The value of the safety height parameter is determined based on the clamping height of the workpiece and the structural dimensions of the machining head; for example, the safety height parameter is set to 10 mm above the highest surface of the workpiece. The traverse speed of the rapid traverse phase is obtained from the rapid traverse speed parameters of the CNC system, for example, 300 mm / s. The slow approach phase is responsible for slowly lowering the machining head from a safe position vertically to the breakpoint coordinates. The traverse speed of the slow approach phase is obtained from the approach speed parameters of the CNC system, for example, 10 mm / s. During the slow approach phase, a position hold command is sent to the servo drive of the follow-up control axis. The servo drive maintains the current position of the follow-up control axis during the descent of the machining head, preventing accidental drift of the follow-up control axis due to gravity or inertia. After the machining head reaches the breakpoint coordinates, the current coordinate values ​​of the machining head in the three translational directions are read. Each component of the current coordinate value is compared with the corresponding component of the breakpoint coordinates. Positioning is confirmed as complete when the deviation of each component is less than the positioning tolerance. The positioning tolerance is obtained from the positioning accuracy parameters of the CNC system, and the value of the positioning tolerance is, for example, 1 micrometer.

[0034] After the machining head is positioned to the breakpoint coordinates, before the laser emission command is triggered, the acceleration and position commands from the guide trajectory data sequence stored in step S3 are sent point-by-point to the servo control axis. The system reads commands from the guide trajectory data sequence cycle by cycle according to the control cycle. The guide trajectory data sequence contains multiple discrete time points arranged in chronological order, each corresponding to an acceleration and position command. The acceleration command is the acceleration value that the servo control axis should execute at the corresponding discrete time point, and the position command is the position coordinate that the servo control axis should reach at the corresponding discrete time point. Within each control cycle, the system reads the acceleration and position commands corresponding to the current cycle and sends them to the servo driver of the servo control axis via the data bus. After receiving the acceleration command, the servo driver writes it into its acceleration command register; after receiving the position command, it writes it into its position command register. At the beginning of the next control cycle, the servo driver drives the servo control axis to move according to the acceleration value in the acceleration command register and the position coordinate in the position command register. The CNC system sets a laser emission flag, which is set to a disabled state when the guide trajectory begins execution. In the disabled state, even if the CNC system receives a laser emission request, it will not issue a laser emission command. The state of the laser emission flag is rewritten to an enabled state by the CNC system after detecting that the dynamic response state has been established. The enabled state removes the shielding of the laser emission command.

[0035] The servo driver drives the follow-up control axis to accelerate along the guide trajectory based on acceleration and position commands. Initially, the follow-up control axis is stationary. After receiving the acceleration command in the first control cycle, the servo driver starts accelerating the follow-up control axis from zero speed. The acceleration value given by the acceleration command is the acceleration amplitude calculated in step S3 based on the margin and reference acceleration. This acceleration amplitude remains constant throughout the acceleration phase of the guide trajectory. Under acceleration, the speed of the follow-up control axis gradually increases from zero. Simultaneously, the servo driver performs closed-loop adjustment of the follow-up control axis's position based on the position command received within the same control cycle, making the actual position of the follow-up control axis approach the position coordinates given by the position command. During the acceleration motion, the follow-up control axis moves along the curvature change direction of the guide trajectory and matches the spatial curve of the guide trajectory. The position coordinates and velocity value at the end of the guide trajectory correspond to the state required for the follow-up control axis to synchronize with the surface contour. In this state, the velocity direction of the follow-up control axis is consistent with the curvature change direction of the surface contour at that point, and the velocity magnitude matches the following speed required for the curvature change of the surface contour.

[0036] During acceleration, the actual position following error of the servo axis is detected synchronously. The detection method is as follows: at the end of each control cycle, the actual position following error value at the current moment is read from the following error register of the servo drive of the servo axis, and simultaneously, the expected following error at the corresponding discrete moment is obtained from the guide trajectory data sequence. The expected following error is stored as an additional field in the guide trajectory data sequence for each discrete moment when the guide trajectory is generated in step S3. This additional field is read along with the guide trajectory data sequence in step S4, thus obtaining the expected following error for each discrete moment. Immediately after the actual position following error is read in each control cycle, the actual position following error is compared with the expected following error, and the absolute difference between the actual position following error and the expected following error is calculated. When the absolute difference for a certain control cycle is less than a preset following error judgment threshold, the actual position following error is determined to be consistent with the expected following error at the corresponding moment in the guide trajectory. The preset following error judgment threshold is read from the algorithm parameter table of the CNC system. The preset following error judgment threshold is set based on the allowable fluctuation ratio of the machining tolerance range. For example, if the allowable fluctuation ratio of the machining tolerance range is set to 10%, the preset following error judgment threshold is 0.5 micrometers when the machining tolerance range is 5 micrometers. The preset following error judgment threshold represents the upper limit of the residual deviation that the following error can exist when synchronization has been established. When the actual position following error is determined to be consistent with the expected following error at the corresponding moment in the guide trajectory, it is determined that the servo control axis has reached the dynamic response state of synchronization with the curved surface contour. All remaining position commands in the guide trajectory starting from the next control cycle are marked as synchronous following commands, so that the servo control axis continues to perform following motion along the curved surface contour under the drive of the synchronous following commands, providing a continuous and stable focus following basis for subsequent laser beam output. If the absolute difference between the actual position following error and the expected following error is not less than the preset following error judgment threshold when the entire guide trajectory is completed, it is determined that the dynamic state recovery has not met the expected conditions. The triggering of the laser output command in step S5 is paused and a warning signal is sent to the warning interface of the CNC system. The warning signal is used to prompt the operator to check whether there are any abnormalities in the follow-up control axis or the machining environment.

[0037] A dynamic scheduling method for laser engraving tasks, wherein step S5 further includes: After step S4 completes the execution of the guide trajectory and determines that the follower control axis has reached a dynamic response state synchronized with the surface contour, the CNC system enters step S5 to check whether the follower control axis has reached the end point of the guide trajectory and established a dynamic tracking state synchronized with the surface contour. The detection process includes two parallel condition checks: the first condition check checks the arrival status of the guide trajectory end point, and the second condition check checks the establishment status of the dynamic tracking state. The detection is considered successful only after both condition checks are passed.

[0038] The method for detecting the arrival status of the guide trajectory endpoint is as follows: In each control cycle, the actual position coordinates of the servo axis are read from the position feedback register of the servo drive of the servo axis. Simultaneously, the position coordinates corresponding to the endpoint of the guide trajectory are read from the guide trajectory data sequence stored in step S3 as the endpoint reference coordinates. Each component of the actual position coordinates is compared with the corresponding component of the endpoint reference coordinates. When the deviation of each component is less than the preset endpoint determination threshold, it is determined that the servo axis has reached the endpoint of the guide trajectory. The preset endpoint determination threshold is read from the algorithm parameter table of the CNC system. The preset endpoint determination threshold is set based on the positioning accuracy index of the servo axis. For example, the preset endpoint determination threshold is set to 0.5 micrometers. The preset endpoint determination threshold represents the maximum allowable residual deviation between the actual position and the endpoint reference position when the endpoint is determined to have been reached.

[0039] The detection method for establishing the dynamic tracking state is as follows: The actual position tracking error of the current control cycle is read from the tracking error register of the servo drive of the servo axis. The tracking error determined to be consistent in the final stage of the acceleration process in step S4 is used as the stable tracking reference value. The actual position tracking error is compared with the stable tracking reference value. When the absolute difference between the actual position tracking error and the stable tracking reference value is less than the preset dynamic tracking judgment threshold for multiple consecutive control cycles, it is determined that the servo axis has established a dynamic tracking state synchronized with the curved surface contour. The preset dynamic tracking judgment threshold is read from the algorithm parameter table of the CNC system. The preset dynamic tracking judgment threshold is set based on the allowable fluctuation range of the focus stability in the engraving process. For example, the allowable fluctuation range is 20% of the allowable machining range. When the allowable machining range is 5 micrometers, the preset dynamic tracking judgment threshold is 1 micrometer. The preset dynamic tracking judgment threshold represents the upper limit of the instantaneous fluctuation of the tracking error when dynamic tracking is determined to be established. The number of consecutive control cycles is obtained from the filtering parameters of the CNC system. For example, the value of the filtering parameter is 5 control cycles. This value ensures that the judgment result will not be misjudged due to a single instantaneous disturbance.

[0040] When both of the above conditions are met, the CNC system detects that the servo control axis has reached the end point of the guide trajectory and has established a dynamic tracking state synchronized with the surface contour, immediately triggering the laser output command. Upon triggering the laser output command, a laser start signal is sent to the laser control interface. The timing of the laser start signal is synchronized with the CNC system's control cycle, meaning it is issued at the start of the next control cycle after the detection result is met. After receiving the laser start signal, the laser control interface starts the laser according to the laser power level and pulse frequency parameters set in the interrupted task's task parameters, causing the laser to output a laser beam according to the preset parameters. The laser power level and pulse frequency parameters set in the task parameters are loaded into the running memory by the CNC system from the task file before the interrupted task begins processing. When the laser output command is triggered, the CNC system directly reads the corresponding parameters from the running memory and sends them to the laser control interface. The delay between the triggering time of the laser beam emission command and the time when the servo control axis reaches the end of the guide trajectory does not exceed the duration of one control cycle. This delay ensures the timing accuracy between the establishment of the dynamic tracking state of the servo control axis and the actual emission of the laser beam.

[0041] After the laser beam emission command is triggered, starting from the remaining engraving command start point corresponding to the breakpoint coordinates, the remaining engraving command sequence is retrieved from the CNC task file and sent line by line to the execution unit to continue the surface engraving process of the interrupted task. The starting point of the remaining engraving command is determined as follows: the trajectory node index corresponding to the breakpoint coordinates is read from the breakpoint information structure saved in step S1. The trajectory node index points to the starting coordinate position of the remaining engraving path in the surface contour data. The CNC command line corresponding to this starting coordinate position is taken as the starting point of the remaining engraving command. All CNC command sequences of the interrupted task are read from the CNC task file. The storage order of the CNC command sequences in the task file is consistent with the processing order. Taking the starting point of the remaining engraving command as the boundary, a continuous subsequence from the starting point of the remaining engraving command to the last command is extracted as the remaining engraving command sequence. The remaining engraving instruction sequence is loaded into the CNC system's instruction buffer. The instruction buffer manages the transmission of instructions in a first-in, first-out (FIFO) order. In each control cycle, one CNC instruction is retrieved from the buffer's output. The instruction type and parameters of this instruction are parsed. Instruction types include linear interpolation, circular interpolation, servo control, and laser control. After parsing, the CNC system sends this instruction to the corresponding execution unit via the data bus. The execution unit drives the translational axis of the machining head, the servo control axis, or the laser to perform the corresponding action, depending on the instruction type. During the sequential transmission of the remaining engraving instruction sequence, the servo control axis maintains the established dynamic tracking state, following the changes in the curved surface contour in real time. The laser beam acts on the workpiece surface under the focus tracking of the servo control axis, continuing the engraving process of the remaining path from the breakpoint.

[0042] When the last instruction in the remaining engraving instruction sequence is executed, the CNC system sends a laser shut-off signal to the laser control interface, the laser stops emitting light, and the surface engraving process of the interrupted task is completed.

[0043] Example 2: Figure 2 A schematic diagram of a dynamic scheduling system for laser engraving tasks according to the present invention is provided. The dynamic scheduling system for laser engraving tasks includes the following modules: The information recording module is used to record the breakpoint coordinates, surface contour data, dynamic following status of the follow-up control axis at the moment of interruption, and duration of interruption when a preemptive interruption of the curved surface engraving task is triggered during the dynamic scheduling of laser engraving. The status judgment module is used to assess the extent to which the workpiece thermal relaxation deformation exceeds the curvature tolerance domain of the remaining engraving path based on the duration of the interruption when the scheduling resumes the interrupted task, and to determine whether the follow-up control axis needs to perform dynamic status recovery. The trajectory generation module is used to evaluate the margin of the initial following error relative to the machining tolerance when directly following the remaining path in a stationary state using dynamic following state and surface profile data if dynamic state recovery is required, and to generate a guide trajectory based on the margin to enable the dynamic response of the follower control axis to be synchronously reconstructed with the surface profile. The operation control module is used to position the processing head to the breakpoint coordinates and control the follow-up control axis to run along the guide trajectory before the laser beam is emitted; The instruction execution module is used to start laser light output and continue executing the remaining engraving instructions from the breakpoint position after the follow-up control axis completes the guide trajectory and establishes a dynamic tracking state.

[0044] All calculations involved in the embodiments are dimensionless numerical calculations, and the preset parameters and thresholds in the calculations are set by those skilled in the art according to the actual situation.

[0045] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, in the form of a computer program product.

[0046] Those skilled in the art will recognize that the modules and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and inventive constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0047] In addition, the functional modules in the various embodiments of this application can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module.

[0048] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or modules may be electrical, mechanical, or other forms.

[0049] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0050] In conclusion, the above description is only 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. A dynamic scheduling method for laser engraving tasks, characterized in that, Includes the following steps: S1: During the dynamic scheduling of laser engraving, when a preemptive interruption of the curved surface engraving task is triggered, the breakpoint coordinates, curved surface contour data, dynamic following status of the follow-up control axis at the time of interruption, and interruption duration are recorded. S2: When the scheduler resumes the interrupted task, it assesses the extent to which the workpiece thermal relaxation deformation exceeds the curvature tolerance domain of the remaining engraving path based on the duration of the interruption, and determines whether the follow-up control axis needs to perform dynamic state recovery. S3: If dynamic state recovery is required, the dynamic following state and surface profile data are used to evaluate the margin of the initial following error relative to the machining tolerance when directly following the remaining path in a stationary state, and the margin is used to generate a guide trajectory that enables the dynamic response of the follower control axis to be synchronously reconstructed with the surface profile. S4: Position the processing head to the breakpoint coordinates and control the follow-up control axis to run along the guide trajectory before the laser beam is emitted; S5: After the follow-up control axis completes the guide trajectory and establishes the dynamic tracking state, the laser output is turned on to continue executing the remaining engraving instructions from the breakpoint position.

2. The laser engraving task dynamic scheduling method according to claim 1, characterized in that, S1 includes: When the preemptive interrupt is triggered, the speed feedforward and position following error output by the servo drive of the follow-up control axis are read, combined into a dynamic following state and saved. Start a timing process to record the time elapsed from the generation of the preemptive interrupt instruction to the arrival of the scheduling recovery instruction, and obtain the interrupt duration; The current command position is obtained from the CNC system as the breakpoint position coordinates. The surface contour data corresponding to the interrupted task is retrieved from the task file. The breakpoint position coordinates are mapped to the corresponding trajectory nodes in the surface contour data and then the surface contour data is saved.

3. The laser engraving task dynamic scheduling method according to claim 1, characterized in that, S2 include: When the scheduler resumes the interrupted task, the coordinates of the breakpoint are mapped to the surface contour data, the remaining carving path from the breakpoint to the carving end point is determined, and the curvature tolerance domain of each point on the remaining carving path is extracted from the surface contour data. Based on the duration of the interruption and the thermal relaxation characteristics of the workpiece material, the thermal relaxation deformation generated by the workpiece during the interruption is obtained. By comparing the thermal relaxation deformation with the curvature tolerance domain, the degree of excess is obtained; If the degree exceeds the limit, it indicates that the thermal relaxation deformation has exceeded the curvature tolerance range, and it is determined that the follower control axis needs to perform dynamic state recovery.

4. The laser engraving task dynamic scheduling method according to claim 3, characterized in that, The thermal relaxation deformation is obtained based on the duration of the interruption and the thermal relaxation characteristics of the workpiece material, including: Extract the workpiece material type from the task file of the interrupted task, and call the corresponding thermal time constant and thermal expansion coefficient according to the workpiece material type; The duration of the interruption is compared with the thermal time constant to determine the thermal relaxation stage of the workpiece during the interruption. Based on the thermal relaxation stage and the coefficient of thermal expansion, the contour deformation displacement of the workpiece caused by the temperature gradient decay from the interruption time to the recovery time is calculated as the thermal relaxation deformation.

5. The laser engraving task dynamic scheduling method according to claim 1, characterized in that, S3 include: If dynamic state recovery is required, analyze the dynamic following state to obtain the speed feedforward and position following error of the follow-up control axis at the time of interruption. The direction and rate of curvature change of the remaining carving path at the breakpoint are determined using surface contour data; Assuming that the following is started directly from a stationary state, the initial following error is obtained based on the velocity feedforward and the rate of change of curvature. Obtain the processing tolerance range corresponding to the interrupted task, and compare the initial following error with the processing tolerance range to obtain the excess margin; Using the excess margin as the acceleration amplitude adjustment amount for the guide trajectory, a guide trajectory is generated along the curvature change direction to transition the follower control axis from rest to synchronization with the surface profile.

6. The dynamic scheduling method for laser engraving tasks according to claim 5, characterized in that, Obtaining excess margin includes: The ratio of the initial following error to the allowable processing range is calculated. When the ratio is greater than the preset judgment threshold, the ratio will be converted into an excess margin. Among them, the excess margin characterizes the order of magnitude of the initial following error exceeding the allowable range of the processing when the following is directly started in a static state.

7. The laser engraving task dynamic scheduling method according to claim 1, characterized in that, S4 include: Drive the machining head from its current position to the machining breakpoint at the time of the interruption, according to the breakpoint coordinates. Before the laser beam emission command is triggered, the acceleration and position commands arranged sequentially in the guide trajectory are sent to the follow-up control axis point by point; The follower control axis performs accelerated motion along the guide trajectory and reaches a dynamic response state synchronized with the surface profile at the end of the guide trajectory.

8. The laser engraving task dynamic scheduling method according to claim 7, characterized in that, Controlling the follow-up control axis to run along the guide trajectory includes: The servo control axis is driven to accelerate from zero speed according to the acceleration commands arranged in sequence in the guide trajectory; The actual position following error of the servo control axis is detected synchronously during acceleration. When the actual position following error is consistent with the expected following error at the corresponding moment in the guide trajectory, it is determined that the follow-up control axis has reached the dynamic response state synchronized with the surface contour, and the remaining position commands in the guide trajectory are executed as synchronous following commands.

9. The laser engraving task dynamic scheduling method according to claim 1, characterized in that, S5 include: Detect whether the follow-up control axis has reached the end point of the guide trajectory and has established a dynamic tracking state synchronized with the surface profile; When the endpoint of the guide trajectory is detected and a dynamic tracking state has been established, the laser emission command is immediately triggered. Starting from the starting point of the remaining engraving instructions corresponding to the breakpoint coordinates, the remaining engraving instruction sequence is retrieved from the CNC task file and sent line by line to the execution unit to continue the surface engraving process of the interrupted task.

10. A dynamic scheduling system for laser engraving tasks, used to implement the dynamic scheduling method for laser engraving tasks according to any one of claims 1-9, characterized in that, Includes the following modules: The information recording module is used to record the breakpoint coordinates, surface contour data, dynamic following status of the follow-up control axis at the moment of interruption, and duration of interruption when a preemptive interruption of the curved surface engraving task is triggered during the dynamic scheduling of laser engraving. The status judgment module is used to assess the extent to which the workpiece thermal relaxation deformation exceeds the curvature tolerance domain of the remaining engraving path based on the duration of the interruption when the scheduling resumes the interrupted task, and to determine whether the follow-up control axis needs to perform dynamic status recovery. The trajectory generation module is used to evaluate the margin of the initial following error relative to the machining tolerance when directly following the remaining path in a stationary state using dynamic following state and surface profile data if dynamic state recovery is required, and to generate a guide trajectory based on the margin to enable the dynamic response of the follower control axis to be synchronously reconstructed with the surface profile. The operation control module is used to position the processing head to the breakpoint coordinates and control the follow-up control axis to run along the guide trajectory before the laser beam is emitted; The instruction execution module is used to start laser light output and continue executing the remaining engraving instructions from the breakpoint position after the follow-up control axis completes the guide trajectory and establishes a dynamic tracking state.

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