Method of operating a laser plotter for cutting, engraving, marking and / or drawing on a workpiece and laser plotter for engraving, marking and / or drawing on a workpiece - Patents.com

Abstract

The present invention relates to a laser plotter and a method of operating a laser plotter 1 for cutting, engraving, marking and / or drawing a workpiece 7. At least one beam source 4 is installed in a housing 3 of said laser plotter 1 as a laser 5, 6, during operation of the beam source 4 a laser beam 10 is deflected via a deflection element 11 to a focusing device 12, control is performed by a control device 13 based on set parameters and / or a loaded job, and for imaging the installed workpiece 7, preferably a work table 9 or a work chamber 8, is captured by at least one camera 23. Data, in particular a job 18, is received by a computing unit 27 and a trajectory plan is calculated offline by said computing unit 27 or an external cloud solution or component 15, whereby said trajectory plan and other data are transmitted to an SPS controller 26a or a stored program control software unit 26b, and subsequently individual target data, in particular said trajectory plan, such as speed data, is transmitted step by step for a scan cycle or scan time 40 from said SPS controller 26a or said stored program control software unit 26b via an industry bus 25, in particular an EtherCat bus, to at least modules 29, 30, 31 for axis control and laser control. For each periodic scan time 40, at least the captured position and velocity information, in particular axis positions 41 and velocities, is transmitted from the axis modules 29, 30 to the laser control module 31, whereby an estimation 39 or calculation 39 of one or more axis positions 42 predicted for a future time point 43 is performed by the laser control module 31 or by a universal board, in particular a Trotec universal board, in order to enable laser control, in particular control signals for the lasers 5, 6, at the correct time at the pre-set position of the focusing device 12.

Description

[Technical field]

[0001] The invention relates to a method for operating a laser plotter for cutting, engraving, marking and / or drawing on a workpiece and to a laser plotter for engraving, marking and / or drawing on a workpiece according to claims 1 and 12. [Background technology]

[0002] A method for predetermining the processing position of a laser beam is known from DE 102004043175. In this method, a laser head is fixed to a robot arm. The impact point of the laser beam on the surface of the workpiece is tracked by a camera. The actual position of the laser beam is derived from the position of the camera, and the processing position is calculated from the difference between the target position and the actual position corresponding to this target position.

[0003] Furthermore, laser processing machines or laser plotters are known from the prior art, in which one or more beam sources, in particular lasers, are operated. For this purpose, a laser beam is transmitted from the laser source via a deflection element to a focusing device. In this case, the laser beam is deflected in the focusing device towards the workpiece and focused via optical elements, in particular lenses. In this case, the individual components, in particular the laser control module, the axis module, the suction unit, the camera, etc., are controlled by a dedicated control device. The set and transmitted parameters or the transmitted job are processed by the control device. In conventional architectures, it is common for the laser control module to be directly connected to the position sensors of the axis modules or the axis control, since a process specific to the control and the architecture is used. This is achieved so that, in order to carry out the laser processing of the workpiece at the desired or preset position of the processing head, in particular the collector, when the preset axis position is reached, the laser pulse is fired at the exact time, i.e. the laser control module is always informed about the actual position of the processing head, in particular the collector, by the connection with the position sensor, so that the laser or the laser pulse is activated at the exact time. A disadvantage here is that due to the specific processes, a great deal of effort is required in terms of hardware and software technology when setting up a laser processing machine, in particular a laser plotter. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] German Patent No. 102004043175 Summary of the Invention [Problem to be solved by the invention]

[0005] It is therefore an object of the present invention to provide a method for operating a laser plotter for cutting, engraving, marking and / or drawing workpieces and a laser plotter, in which on the one hand the above-mentioned disadvantages are avoided and on the other hand a standard architecture is used. [Means for solving the problem]

[0006] This problem is solved by the present invention. Preferred arrangements and / or methods are set out in the dependent claims.

[0007] This problem is solved by a method for operating a laser plotter for cutting, engraving, marking and / or drawing workpieces, in which data, in particular a job, is received by a computing unit, a trajectory plan is computed offline by the computing unit or an external cloud solution or component, the trajectory plan and other data are then transmitted to an SPS control or a stored program control software unit, and subsequently individual target data, in particular the trajectory plan, such as speed data, for each step of a scan cycle or scan time, are transmitted from the SPS control or the stored program control software unit via an industry bus, in particular an EtherCat bus, to at least modules for axis control and laser control. In this case, at least the captured position and speed information, in particular the axis positions and speeds, for the periodic scanning time are transmitted from the axis module to the laser control module, followed by an estimation or calculation of one or more axis positions predicted for a future time point being performed by the laser control module or by a universal board, in particular a Trotec universal board, in order to activate control signals for laser control at the correct time, in particular control signals for operating the laser at a pre-set position of the focusing device.

[0008] In this case, it is advantageous that the estimation of the position or axis position provides the possibility that a standard industry bus can be used for such laser processing machines, in particular laser plotters, without any loss of quality. In order to be able to use it to synchronize the laser to the axis position of the collector, the scanning time or scanning cycle in the case of a standard industry bus is generally too long or essentially not constant. That is to say, the position of the collector at the time of sending the data, in particular the measured or captured axis position, is too early with respect to the scanning time for activating the laser. According to the invention, this is solved in such a way that the estimation of the axis position is performed between the scanning times or between the scanning cycles. As a result, the axis position at which the laser has to be activated in order to apply it to the workpiece at the desired place or position can be calculated for a future time point. That is to say, several position data used to emit laser pulses are generated or calculated within one period of time. As a result, the long scanning times do not occur due to the estimation of the position. It can therefore be said that due to the estimation, the laser is synchronized to the axis position.

[0009] It is advantageous if the axis module periodically transmits or communicates the position and velocity data received from the position sensor and the next axis position according to the calculated trajectory plan to the laser control module via the industry bus every scan time. It is thus achieved that the final values ​​are planned for simulating or calculating the estimation. As a result, the direction of the calculation, in particular whether the calculation is increasing or decreasing, is preset. Thus, there is always only a small deviation from the planned trajectory.

[0010] It is advantageous if the laser control module or the universal board, in particular the Trotec universal board, performs a calculation or estimation of the predicted system states, in particular the predicted axis positions, for a future time point by the data transmitted from the axis modules based on a time integration method, in particular the fourth-order Runge-Kutta method. This achieves that integration methods proven from the prior art can be used. The integration is therefore easily performed by software techniques.

[0011] It is advantageous if the number of calculated future estimates, in particular the axis positions calculated for the calculated future time points, is settable or can be set. This achieves that the number of estimates can be easily adapted to various applications. In this case, the higher the number of estimates, the better the quality of the laser processing, since the time points and axis positions for outputting the control signals for activating the laser are more accurate. If the number of estimates is smaller, the time step width Δt between the individual time points increases, so that the control signals for the laser can no longer be output accurately. The laser used has, for example, a laser frequency of 200 kHz. As a result, for a scanning time of 200 μs of the industry bus in the optimal case, i.e. for the highest resolution, 40 different estimates can be performed or calculated. That is, in total, one estimate of the axis position can be performed in 5 μs.

[0012] It is advantageous if the estimation corresponds exactly to the measured or transmitted axis positions at the beginning of the simulation period, and as the simulation time progresses differences arise between the planned and simulated axis positions. This achieves that the difference or deviation of the estimated axis positions from the planned axis positions is always only very small. The simulation period is the period existing between two scan times of the industry bus.

[0013] It is also useful to correct the difference for each scan time by using measured or known axis positions. This ensures that the axis positions are accurately corrected after each scan time. As a result, the difference is always only small. In this case, the position transmitted at the start of the estimation is used as the new position for the estimation.

[0014] It is advantageous if the time of the SPS controller or stored program control software is synchronized with the time of the modules, in particular the axis controller or axis modules and the laser controller or laser control modules, or with the time of the Trotec universal board. In this case, a synchronization signal is sent from the SPS controller or stored program control software. As a result, the SPS clock runs in synchronism with the slave clocks, in particular the axis modules and the laser control modules.

[0015] However, it is also advantageous if the scanning time of the industry bus used, in particular the EtherCat Fast bus, is between 150 μs and 300 μs, in particular 200 μs, so that depending on the scanning time, data is transferred from the master to the slave or from the slave to the slave or from the slave to the master.

[0016] It is advantageous if the time periods between the time points, in particular between the time points, for the estimation of the axial position are shorter than the time periods between the scan times, so that at least one, preferably several, time points between the scan times are used to estimate or calculate the axial position.

[0017] It is advantageous to have a method in which the difference in the estimation of the axis positions depends on at least one of the following: the accuracy of the measurement of the starting conditions, the choice of the effects taken into account in the model, the accuracy of the coefficients used for the model parameters, in particular the geometry, inertia, friction and elasticity, and the simulation period, whereby it is achieved that the difference in the estimation with respect to the planned or actual axis positions can be kept small due to the incorporated parameters.

[0018] It is advantageous that the results of the trajectory planning, in particular the position, velocity, acceleration, laser power, etc., are transmitted with respect to the scanning time, so that it is achieved that the important information is always transmitted at each scanning time.

[0019] Furthermore, the object of the present invention is solved by a laser plotter for engraving, marking and / or drawing workpieces, in which a computing unit is arranged for receiving and processing data, in particular jobs or graphics and / or texts, which is connected to the SPS control or the stored program control software unit. In this case, at least one axis module and the laser control module are connected to the SPS control or the stored program control software unit via an industry bus. In this case, the laser control module or the universal board, in particular the Trotec universal board, is configured to estimate or calculate expected axis positions for a future time point based on the captured position and speed information, in particular axis positions and speeds, of the axis modules, so that the laser can be operated for a corresponding predefined axis position. In this case, it is advantageously provided for the first time that the possibility is provided in such a way that the laser plotter can be operated by the SPS control or the stored program control software unit and the industry bus, in which the time point for the estimated corresponding axis position is shortened by estimating the axis position for a future time point.

[0020] It is advantageous that the position sensors are arranged in the axis modules, which allows standard modules to be used, thus reducing development costs for expensive proprietary processes.

[0021] Finally, it is advantageous to have a preferably Windows-based computing unit built into the laser plotter, which allows for easy data connection to external components.

[0022] The problem with the use of an industry bus is that the scanning times for transmitting data last too long or the periods between scans are too long in order to be able to control the laser according to the transmitted time position. This is because, when using standard components, in particular the SPS control or the stored program control software and the industry bus, the position sensors of the axis modules are not directly connected to the laser control module, and as a result the laser control module transmits information, in particular the axis positions, only for the scanning times. However, the scanning times are so long that it is not possible to apply an estimation of the axis positions without the inventive solution. By estimating the axis positions, it is achieved that the time points for generating the control signals for the laser can be determined as accurately as possible. Thus, by estimating or calculating the axis positions, the synchronization of the laser control module or the universal board, in particular the Trotec universal board, with the position sensors of the axis modules is simulated. In contrast to this, in the case of the prior art, specific solutions are used in which the position sensors are directly connected or coupled to the laser control module, so that the laser control module is always informed about the position of the focusing device and thus the control signals for activating the laser can be generated at the correct time.

[0023] The following describes the embodiments of the present invention, with the caveat that the present invention is not limited to the embodiments or solutions shown and described, but may be applied to equivalent solutions. [Brief description of the drawings]

[0024] [Figure 1] 1 shows diagrammatically a laser processing machine, in particular a laser plotter, for processing a workpiece by means of a camera system in the cover. [Diagram 2] 1 shows a schematic block diagram of a laser plotter having a computing unit and an SPS control unit. [Figure 2a] 2 shows another block diagram of a laser plotter having a computing unit and an SPS control unit. [Diagram 3] 1 illustrates diagrammatically the operation of the estimation between two scanning cycles. [Figure 4] 10 illustrates a schematic representation of multiple estimations over successive scan cycles. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] First, in different embodiments, the same components are indicated by the same reference numerals or the same component names. In this case, all contents described in the specification may correspond to the same components having the same reference numerals or the same component names. In addition, selected positions such as upper, lower, side, etc. described in the specification correspond to the drawings shown, and when the position is changed, it may correspond to the new position.

[0026] 1 to 4 show an embodiment of a laser processing machine 1, in particular a laser plotter 1. In the case of this laser processing machine 1, for example a camera system 2 is integrated and a method for operating the laser plotter 1 for cutting, engraving, marking and / or drawing on a workpiece is performed.

[0027] In the case of the laser plotter 1 shown, at least one, preferably two beam or laser sources 4 are arranged in the housing 3 as lasers 5, 6. The lasers 5 and 6 act preferably alternately on the workpiece 7 to be processed. The workpiece 7 is arranged or is arranged in the processing chamber 8 of the laser plotter 1, in particular on a processing table 9. In this case, the processing table 9 is preferably adjustable in height. A laser beam 10 emitted from the beam source 4, in particular the laser 5 or 6, is transmitted via a deflection element 11 to at least one movable focusing device 12, from which the laser beam 10 is deflected towards the workpiece 7 and focused for processing. The laser beam 10 deflected towards the workpiece 7 is controlled, in particular the positioning control, by software running on a control device 13. In this case, the workpiece 7 is processed in the XY direction by moving a slide 14, on which the focusing device 12 is also movably arranged, preferably by a belt drive. In this case, for example, in the case of the processing step "gravure printing", the slide part 14 is moved line by line, whereas in the case of the processing step "cutting", the slide part 14 is moved according to the contour to be cut and therefore not moved line by line.

[0028] In the external component 15, in particular a computer, laptop or control device, graphics 16 and / or text 16 are created or loaded by means of commercially available software 17, for example CorelDRAW®, Paint®, etc., or by means of specific application software 17, in particular Ruby. Said graphics 16 and / or text 16 are preferably transferred or transmitted to the control device 13 of the laser processing machine or laser plotter 1 as a job 18. Preferably, the data to be transmitted is transformed by the same or another software, so that the control device 13 can execute the job 18. However, it is also possible that said data is transformed by the control device 13 or by the software of a cloud solution. Naturally, said input can be performed directly in the laser plotter 1 by means of existing input devices 19, for example a touch screen 19 or input keys, or it is also possible that said input is loaded from a storage medium 20, for example a cloud 20a, a USB stick 20b, etc., by means of the corresponding job 18. After the data, in particular the job 18, has been transmitted or directly created or loaded from the storage medium 20, the job 18 is executed by the laser plotter 1, in particular the control device 13 of the laser plotter 1. In this case, it is possible that several jobs 18 can be stored in the laser processing machine 1, in particular the laser plotter 1, and executed in succession. Basically, the application software 17, in particular the Ruby 17, can be called via the cloud 20a. As a result, the graphics 16 and / or the text 16 can be created via the cloud 20a. That is to say, basically, the application software 17, in particular the Ruby 17, is installed in the cloud 20a and can be called by a web browser on a computer. As a result, the graphics 16 and / or the text 16 can be created or loaded subsequently. This creates a job 18 for the laser plotter 1. This job 18 can be sent directly to the laser plotter 1, for example as shown in FIG. 2a, or can be stored in the cloud 20a so that this job 18 can be loaded at a later time.In this case, the computer 15 is also directly connected to the laser processing machine 1, as shown by a dashed line.

[0029] In the case of such a laser processing machine 1, in particular a laser plotter 1, it is necessary for reliability that in order to start the job 18 to be executed when the laser beam 10 acts on the workpiece 7, the cover 21 or door 21, which is preferably made at least partially transparent, as shown in FIG. 1, must be closed. The operator then manually or automatically positions the laser point or laser pointer 22, in particular the laser pointer point 22a, which is coupled to the beam path of the lasers 5, 6 and is deflected by the focusing device 12 towards the processing table 8, on the attached workpiece 7. At the end of the subsequent job 18, the slide 14 and the focusing device 12 are preferably moved to the start position, so that the completed workpiece 7 can be removed. A new processing step can then be started by loading a new workpiece 7 or workpiece 7 to be processed. In this case, it is advantageous that the end of processing is signalled visually or acoustically. As a result, the user does not have to constantly monitor the laser processing machine 1. For the sake of completeness, it is mentioned that even when the cover 21 is open, the movement of the light collecting device 12 with the activated laser pointer 22 is possible, but the lasers 5, 6 cannot be activated.

[0030] Furthermore, it is possible that at least one camera 23 is provided in the camera system 2. In this case, the camera 23 is present in the cover 21. As a result, the mounted workpiece 7 can be recognized. However, it is also possible that more than one camera 23 is arranged in the cover 21 or in the housing 3. The position of the mounted workpiece 7 is captured by the camera 23 and preferably displayed on an external component, in particular a laptop. In this case, the position of the workpiece 7 is preferably captured before the start of the processing or processing step. The light collecting device 12 can be appropriately positioned by the laser pointer 22. For completeness, it is pointed out that recognition of the position of the workpiece 7 is also possible when the cover 21 is open.

[0031] For the novel laser plotter 1, in particular the laser processing machine 1, a novel electronic architecture, in particular the configuration of the control device 13, is proposed, as can be seen diagrammatically in the block diagram of FIG. 2 and FIG. 2a.

[0032] For this purpose, the control device 13 preferably consists of standard (conventional) modules, which are connected as so-called slaves 24 (24a, b, c, d, ...) via an industry bus 25, in particular an EtherCat-Bus 25, to a master 26. In this case, the master 26 is constituted by a standard SPS control unit 26a as shown in FIG. 2 or a stored program control software unit (Soft-SPS) 26b as shown in FIG. 2a. In order to be able to transmit data to the master 26, the master 26 is connected to or directly integrated in a computing unit 27. Likewise, the computing unit 27 can be connected via a data connection to an external component 15, in particular a laptop or a storage medium 20. As a result, the created job 18 or the created or loaded graphics 16 and / or texts 16 can be transmitted to the computing unit 27 in the laser plotter 1. That is, a job 18 or a graphic 16 and / or a text 16 is received by the computing unit 27 from the external component 15, in particular the laptop 15 or from the storage medium 20, in particular the cloud 20a. The computing unit 27 then processes the received data. In this case, a trajectory plan, in particular the trajectory and / or the position of the light collector 12 and / or the movement course / movement pattern of the light collector 12 is calculated offline by the computing unit 27 or by the external cloud solution or by the component 15 and / or the result of said trajectory plan consisting of the position, speed, acceleration, laser power, etc., for processing the workpiece 7. Thus, all positions, trajectories, speeds, accelerations, laser activation, laser power, etc. are known at the start of the operation process. Subsequently, said activation pattern is transmitted to the SPS control unit 26a or the stored program control software unit 26b, in particular the master 26. Thus, subsequently, the trajectory plan, in particular the trajectory and / or the position and / or the movement course / movement pattern and / or the result is transmitted for the scanning cycle 40 or the scanning time 40 step by step.That is, the trajectory plan is calculated offline by the computing unit 27 or by an external cloud solution or component 15 and transmitted to the master 26, in particular the SPS control unit 26a or the stored program control software unit 26b. The master then transmits the results of the trajectory plan, in particular the position, velocity, acceleration, laser power, etc., for the scan time 40 or scan cycle 40 to the slave 24. This results in the next result of the trajectory plan being transmitted for the next scan cycle 40 or the next scan time 40, and so on. In this case, synchronization information is also transmitted. That is, the slave clock is synchronized or runs synchronously with the master clock. Preferably, a Windows-based computing unit 27 is used. In this case, however, other operating systems, such as for example Linux, macOS, etc., can also be used. Preferably, the computing unit 27 is realized by a PC (personal computer). As a result, a simple external communication with the component 15 or the storage medium 20 is possible. In this case, wired and / or wireless connections, eg Ethernet, WLAN etc., may be used to the storage medium 20, in particular the cloud 20a and / or the external component 15.

[0033] In the illustrated embodiment, the master 26 or SPS control 26a or stored program control software 26b has two industry buses 25 and 28. In this case, the industry bus 25 (EtherCat Fast) has a fast scan time 40 of about 200 μs, and the other industry bus 28 (EtherCat Slow) has a significantly slower scan time. The slaves 24 are therefore connected to both industry buses 25 and 28 as required. In this case, the axis control 29, 30 or axis module 29, 30 for at least one X-axis, Y-axis and the laser control 31 or laser control module 31 are connected to the fast industry bus 25 (EtherCat Fast). Other slaves 24 or modules 32-34, such as the safety module 32, the input / output module 33, the infeed axis 34, etc., do not require such a fast cycle scan time 40. As a result, they can be connected to the slower industry bus 28 (EtherCat Slow). Naturally, it is possible that the SPS control unit 26a or the stored program control software unit 26b can be used or operated by only one industry bus 25 or 28, so that all modules 29-34 are controlled via this one industry bus 25 or 28. It is likewise possible to arrange the laser control module 31 on a universal board, in particular a Trotec universal board, on which other components or modules can also be arranged, which can for example undertake the individual processing steps of the laser control module 31. Time delays are avoided by a direct connection via this universal board.

[0034] As a result of using standard components, in particular the SPS control 26a or the stored program control software 26b, for the industry bus 25, 28 (EtherCat), it is not possible that the scanning time 40 for sending and receiving data can be shortened. This long scanning time 40 of the standard industry bus 25, 28 therefore causes the laser 5, 6 to be fired too early or too late with respect to the desired axis position, in particular the position of the light collector 12. As a result, the quality, in particular the quality of the gravure printing, is impaired by said firing too early or too late. If EtherCat Fast is used as the industry bus 25, the fastest possible scanning time 40 is 200 μs. As a result, data can be sent and received in about 200 μs overall. That is, only in the scanning time 40 or the scanning cycle 40, i.e. only in about 200 μs overall, the captured position and speed information of the axis modules 29, 30 can be sent to the laser control module 31 for operating the laser 5, 6. In this case, activation of the lasers 5, 6 requires only a fraction of the scan time 40. As a result, without the solution of the present invention, the lasers 5, 6 would be fired too early in transmitting the position.

[0035] In order to precisely control the laser control module 31, which fires or activates the lasers 5, 6, especially during processing of the workpiece 7 in the gravure printing mode, it is necessary that the control signals for the laser control module 31 are synchronized to the position of the processing head or the light collector 12, especially to the axis modules 29, 30. In laser plotters 1 known from the prior art, it is typical for the laser control module 31 to be electrically connected directly to the position sensors 35, 36 of the axis modules 29, 30. It is thus achieved that the laser pulses are fired precisely at the moment of reaching a preset position, in particular a few microseconds before said arrival. As a result, the lasers 5, 6 are also activated according to the trajectory plan at the precise moment of said arrival of the processing head position.

[0036] In the case of the laser plotter 1 according to the invention, by using standard components, there is no direct connection between the position sensors 35, 36 of the axis modules 29, 30 and the laser control module 31. The position sensors 35, 36 of the axes or drives 37, 38 are connected to the axis modules 29, 30. The position information is input to the axis modules 29, 30 so that this information can be transmitted exclusively according to the scanning time 40. That is, the position information and the speed information are transmitted from the axis modules 29, 30 to the laser control module 31 via the industry bus 25 during the scanning time 40. As a result, the actual position of the axis or the light collector 12 is always known to the laser control module 31 for the scanning time 40. However, in the case of a standard industry bus 25, the scanning time 40 is very long in order to guarantee a time-accurate control of the laser control module 31, in particular of the lasers 5, 6, when the predetermined positions are reached. The length of the scan time 40 is limited by technical conditions such as computation speed, transmission time, transmission delay, which is about 200 μs when the EtherCat bus is used, so that the measured positions of the position sensors 35, 36 and other information such as speed, acceleration, laser power, etc. can be transmitted altogether in only about 200 μs.

[0037] In order to activate the lasers 5, 6 at the correct time or to generate control signals for the laser control, an estimation 39 or calculation 39 of the system state is performed, in particular an estimation 39 of the position of the collector 12 for a future time point between two scanning times 40 or scanning cycles 40, as shown diagrammatically in Figure 3. For this reason, in a graph of position against time, the trajectory or position calculated according to the trajectory plan is plotted as a solid line and the trajectory or position estimation 39 is plotted as a dashed line.

[0038] Starting from the current time point, i.e. the first scan time 40a, the known or measured axis positions 41a transmitted from the axis modules 29, 30 to the laser control module 31 or the universal board, in particular the Trotec universal board, for the scan time 40 are used, and subsequently, an estimation 39 or calculation 39 for the unknown expected axis positions 42a-e for future times 43a-e is performed up to the next scan time 40b. Upon arrival of the next scan cycle 40b or scan time 40, the known or measured axis positions 41b are transmitted again from the axis modules 29, 30 to the laser control module 31 or the universal board, in particular the Trotec universal board, and used as output value for the new estimation 39. In this case, the estimation 39 corresponds exactly to the measured or transmitted axis positions 41 at the beginning of the simulation period. In this case, a difference occurs between the planned and the simulated axis positions 42 over the course of the simulation time. However, the difference is automatically corrected after each scan cycle 40, since after the scan time 40 has elapsed, the known or measured values ​​or axis positions 41 are newly transmitted and used as output values ​​for a new simulation or estimation 39.

[0039] A mathematical-physical model of the mechatronic axis system including the control is the basis for the estimation 39. The mathematical-physical model includes relevant properties and effects such as the geometry, inertia, friction, elasticity, quantification of the position measurements, time delays in the machining, closed-loop control circuits and trajectory planning. This model is mathematically described, for example, by a set of difference equations. For example, the system of equations can be used for the estimation 39 or calculation 39 of the axis positions, which are predicted by a time integration method such as the known fourth-order Runge-Kutta method, in particular an explicit time integration method. For the sake of completeness, it is mentioned that the estimation 39 is performed directly by the laser control module 31 or by a universal board, in particular a Trotec universal board.

[0040] For example, lasers 5, 6 with a laser frequency of 200 kHz are used, so that in the case of a scanning time 40 of 200 μs, a maximum of 40 different position estimates 42 or estimated axis positions 42 can be calculated. That is, the estimates 39 of the estimated axis positions 42 can be calculated overall within 5 μs. In this case, it is naturally conceivable that less than 40 estimates 39 may be performed within a scanning time 40 of 200 μs. In FIG. 3, an embodiment is shown. In this embodiment, only five estimates 39 of axis positions 42a-e are shown within two scanning times 40a,b of 200 μs, for the sake of illustration only. In this case, the actually measured axis positions 41 are always transmitted over the scanning time 40. In this case, it is advantageous that the measured axis positions 41 and the following axis positions 44 are always transmitted by the trajectory plan over the scanning time 40. That is to say, the transmitted axis positions 41 represent the initial state at the start of the estimate 39, and the second axis position 44 desired according to the trajectory plan represents the state at the end of the estimate 39. In this case, further position estimates 39 of the axis positions 42 lying between these estimates 39 are calculated, in particular by means of a fourth order Runge-Kutta integration. As a result, the laser control module 31 or the universal board, in particular a Trotec universal board, is informed at the exact time by the planned or estimated axis positions and can therefore activate the lasers 5, 6 at the exact time so that they fire in the desired final positions.

[0041] Therefore, the estimation 39 of the multiple axis positions 42 is important, since the firing of the laser 5,6 requires a part of the period or time interval during which the measured axis positions 41 are transmitted according to the scan cycle 40 or scan time 40. Therefore, based on the estimation 39 of the axis positions 42 for a shorter time point 43 in the future, the laser 5,6 is in fact synchronized to the estimated axis positions 42. As a result, the laser 5,6 can be activated by a control signal for the estimated axis positions 42, so that the laser beam 10 hits the workpiece 7 for the exact time point 43 and axis position 42. In this case, the resolution of the estimations 39 performed, i.e. the number of estimations 39, can be set. In the case of 40 maximally achievable estimations 39, the maximum resolution is achieved, since in fact the laser 5,6 is activated, for example, by the last estimation 39 and is therefore operable for the exact time. In contrast, if a smaller number of estimations 39 are performed or set, the laser 5,6 is activated a little earlier.

[0042] By means of these estimates 39, it is achieved that the periods between two scan times or the time intervals during which there is no value for the axis position are shortened. It is thus achieved that the laser control module 31 or the universal board, in particular a Trotec universal board, is always informed about the position of the focusing device 12 on the basis of the estimated axis positions 42. As a result, the control signals for the lasers 5, 6 are activated according to the predetermined positions, so that the laser beam 10 strikes the workpiece 7 to be processed at the desired position.

[0043] Furthermore, in FIG. 4, a graph of the position against time is shown by a number of trajectories or positions of the trajectory plan and the corresponding estimates 39 of the axis positions 42 shown in dashed lines. In this case, several successive scan time intervals are depicted. Furthermore, in this case, it is important that the control signals for the beam source 4, in particular the laser 5, 6, are synchronized with the position of the collector 12, in order to precisely control the beam source 4, in particular the laser 5, 6, during processing, in particular in the gravure printing mode. This is carried out by an estimate 39 or calculation of several axis positions 42 between the scan times 40. Furthermore, it is clear that for each scan time 40, the transmitted axis positions 41 are used for the new estimate 39. As a result, at the start of the estimate 39, the transmitted axis positions 41, in particular measured by the position sensors 35, 36, are used. As a result, the differences occurring between the measured axis positions 41 and the estimated axis positions 42 are kept as small as possible. For the sake of completeness, it is mentioned that the individual axis positions 42 for the time points 43 as shown in FIG. 3 are not depicted in FIG. 4 for the sake of clarity.

[0044] Basically, it can be said that a method for operating a laser plotter 1 for cutting, engraving, marking and / or drawing a workpiece 7 is described according to the invention. In the method, at least one beam source 4 is installed in the housing 3 of the laser plotter 1 as a laser 5, 6. In this case, when the beam source 4 is operated, a laser beam 10 is deflected via a deflection element 11 to a focusing device 12. In this case, the control is carried out by a control device 13 on the basis of set parameters and / or a loaded job. In this case, preferably a processing table 9 or a processing chamber 8 is captured by at least one camera 23 to capture the installed workpiece 7. In this case, the data, in particular the job 18, is received by a preferably Windows-based computing unit 27. Thereby, a trajectory plan is calculated offline by the computing unit 27 or an external cloud solution or component 15. Thereby, the trajectory plan and other data are sent to the SPS control unit 26a or the stored program control software unit 26b, and then the individual target data are sent step by step from the SPS control unit 26a or the stored program control software unit 26b via the industry bus 25, in particular the EtherCat bus, to the modules 29, 30, 31 for axis control and laser control. In this case, every periodic scan time 40, in particular every approx. 200 μs in total, the captured position information 41 and velocity information 41 are sent from the axis control unit or axis module 29, 30 to the laser control or laser control module 31. Thereby, an estimation 39 or calculation 39 of one or more axis positions 42 for a future time point 43 is performed by the laser control module 31 in order to activate or output control signals for the laser control, in particular the laser source or laser 5, 6, at the correct time at the preset position of the focusing device 12.

[0045] For this purpose, a laser plotter 1 is configured for engraving, marking and / or drawing workpieces, comprising a processing chamber 8 for placing a workpiece 7, at least one, but preferably two, beam sources 4 as lasers 5, 6, corresponding deflection elements 11, a preferably movable focusing device 12 and a control device 13 for controlling the slide 14, preferably driven by a belt drive, with the focusing device 12 movably arranged on the slide 14. In this case, a computing unit 27 is arranged, which is connected to the SPS control unit 26a or the stored program control software unit 26b, for receiving and processing data, in particular jobs 18 or graphics 16 and / or texts 16. In this case, at least one axis module 29, 30 and a laser control module 31 are connected to the SPS control unit 26a or the stored program control software unit 26b via an industry bus 25, 28. In this case, the laser control module 31 is configured to estimate 39 or calculate 39 a predicted axis position 42 for a future time point 43 based on the captured position and velocity information, particularly the axis positions and velocities, of the axis modules 29, 30. This allows the lasers 5, 6 to be actuated to the corresponding predetermined axis positions 42.

[0046] It is important for optimal functioning of the individual modules 29, 30, 31, especially the laser control module 31, that all slave clocks run in sync with the master clock. For this reason, synchronization information is transmitted from the master.

[0047] The Soft-SPS 26b (stored program control software unit 26b) is a software program that is an improvement of the conventional stored program control unit (SPS control unit 26a). This means both functionality and non-functional features such as robustness and real-time behavior. The Soft-SPS 26b is at least composed of a PC - typically an industrial PC, an embedded PC or a box PC -, SPS software and input / output modules and / or an industry bus. In this case, the Soft-SPS 26b is or can be integrated into the computing unit 27.

[0048] The SPS control 26a (stored program control) is a digitally programmed device which is used to control (open loop control) or regulate (closed loop control) machines or installations. In the simplest case, the SPS control 26a has inputs, outputs, an industry bus, an operating system into which application programs can be loaded, and interfaces. The SPS control 26a can be realized in a very diverse way, for example as a separate device (module), a PC plug-in card, software emulation, etc.

[0049] For completeness, it is mentioned that the trajectory planning is generally performed "off-line", i.e. before the actuation or marking steps, but it is also possible that the actuation or marking steps are already started or executed while the trajectory planning is not yet completed, i.e. the actuation or marking steps start already during the calculation with a time delay relative to the trajectory planning.

[0050] Basically, it can be said that the trajectory planning corresponds to the actual movement progression, whereas the estimation corresponds to the simulated position. It is also possible that the inventive solution can be adapted and used in other laser processing machines, in particular in galvanometer lasers or galvanometer marking lasers.

[0051] It is expressly pointed out that the present invention is not limited to the illustrated embodiment, but may include other configurations and structures.

Claims

1. A method for operating a laser plotter (1) for cutting, engraving, marking and / or drawing on a workpiece (7), A beam source (4) as at least one laser (5, 6) is installed in the housing (3) of the laser plotter (1), When the beam source (4) is in operation, the laser beam (10) is deflected towards the focusing device (12) via the deflection element (11). Control is performed by a control device (13) based on set parameters and / or loaded jobs, preferably the workbench (9) or work chamber (8) is captured by at least one camera (23) for photographing the installed workpiece (7), Data, particularly jobs (18), are received by a calculation unit (27), and the trajectory plan is calculated offline by the calculation unit (27) or an external cloud solution or component (15), and subsequently the trajectory plan and other data are transmitted to an SPS control unit (26a) or a storage program control software unit (26b), and thereafter, individual target data, particularly the trajectory plan, such as velocity data, are transmitted step by step with respect to the scan cycle or scan time (40) from the SPS control unit (26a) or the storage program control software unit (26b) to modules (29, 30, 31) for at least axis control and laser control via industry buses (25, 28), particularly the EtherCAT bus. The modules (29, 30) transmit to the laser control module (31) at least the captured position information, velocity information, and the next axis position (41, 42) calculated from the trajectory plan, for the periodic scanning time (40). Subsequently, in order to activate control signals for laser control, particularly control signals for operating the lasers (5, 6) at a preset position of the focusing device (12), at a precise time, the laser control module (31) or a universal circuit board, particularly a Trotec universal circuit board, performs estimation (39) or calculation (39) of one or more expected axis positions (42) for a given future system state, in particular for a given future time (43), based on the transmitted data, A mathematical-physical model of a mechatronic axial system including a control unit forms the basis for the estimation or calculation (39), the method including relevant properties and effects such as geometric form, inertia, friction, elasticity, quantification of position measurement, time delay of processing, closed-loop control circuits and trajectory planning.

2. The method according to claim 1, characterized in that the axis modules (29, 30) periodically transmit or transmit to the laser control module (31) via the industry bus (25) the position data and velocity data received from the position sensors (35, 36) and the next axis position (44) calculated from the trajectory plan, at each scanning time (40).

3. The method according to claim 1, characterized in that the laser control module (31) or the universal substrate, in particular the Trotec universal substrate, performs calculation or estimation (39) of a plurality of expected system states, in particular expected axis positions (42), for a future point in time (43) based on data transmitted from the axis modules (29, 30), based on a time integration method, in particular the fourth-order Runge-Kutta method.

4. The method according to claim 1, characterized in that the number of calculated future estimates (39), in particular, the calculated axis positions (42) for a calculated future time (43), are configurable or can be configured.

5. The estimation (39) precisely matches the measured or transmitted axis position (41) at the start of the simulation period. The method according to claim 1, characterized in that a difference occurs between the planned axis position and the simulated axis position (42) as the simulation time progresses.

6. The method according to claim 1, characterized in that the difference is corrected for each scanning time (40) by using the measured axis position (41) or a known axis position (41).

7. The method according to claim 1, characterized in that the time of the SPS control unit (26a) or the stored program control software unit (26b) is synchronized with the time of the modules (29, 30, 31), particularly the axis control unit or axis modules (29, 30) and the laser control unit or laser control module (31).

8. The method according to claim 1, characterized in that the scan time (40) in the industry bus (25) used, particularly the EtherCAT Fast bus, is 150 μs to 300 μs, particularly 200 μs.

9. The method according to claim 1, characterized in that the time intervals (43) for the estimation (39) of the axis position (42), particularly between multiple time intervals (43a to 43e), are shorter than the time intervals between the scanning times (40).

10. The method according to claim 1, characterized in that the difference in the estimation of the axis position depends on the accuracy of the measurement of the starting state, the selection of effects considered in the model, the accuracy of the count values ​​used for model parameters, in particular geometric form, inertia, friction and elasticity, and the simulation period.

11. The method according to claim 1, characterized in that, as a result of the trajectory planning, in particular position, velocity, acceleration, laser output, etc., are transmitted with respect to the scanning time (40).

12. A laser plotter (1) for engraving, marking and / or drawing on a workpiece, comprising: a processing chamber (8) for setting up a workpiece (7); at least one, but preferably two, beam sources (4) as lasers (5, 6); corresponding deflection elements (11); preferably a movable focusing device (12); and preferably a control device (13) for controlling a slide (14) having a focusing device (12) movably positioned on the slide (14) and driven by a belt drive, A calculation unit (27) connected to an SPS control unit (26a) or a storage program control software unit (26b) is provided to receive and process data, particularly jobs (18) or graphics (16) and / or text (16). At least one axis module (29, 30) and a laser control module (31) are connected to an SPS control unit (26a) or a storage program control software unit (26b) via an industry bus (25, 28). The laser control module (31) or universal substrate, particularly Trotec's universal substrate, is configured to estimate (39) or calculate (39) the expected axis position (42) for a future point in time (43) based on the captured position information and velocity information of the axis modules (29, 30), particularly the axis position and velocity. The axis modules (29, 30) are configured to periodically transmit the received position data and velocity data, along with the next axis position calculated from the trajectory plan, to the laser control module (31) at each scanning time. The laser control module is configured to perform calculations or estimations of multiple future system states based on the transmitted data. The lasers (5, 6) are operable to the corresponding predetermined axial positions (42), The laser plotter (1) is configured such that the laser control module (31) or the universal circuit board is based on a mathematical-physical model of the mechatronics axis system including a control unit for the estimation or calculation (39), and the mathematical-physical model includes relevant characteristics and effects such as geometric form, inertia, friction, elasticity, quantification of position measurement, processing time delay, closed-loop control circuit and trajectory planning.

13. The laser plotter (1) according to claim 12, characterized in that position sensors (35, 36) are arranged in the axis modules (29, 30).

14. Preferably, the laser plotter (1) according to claim 12 is characterized in that a Windows-based arithmetic unit (27) is incorporated into the laser plotter (1).

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