Five-axis laser servo control method and application based on model predictive control

Abstract

The present invention discloses a five-axis laser follow-up control method and application based on model predictive control. The method comprises: based on the physical state quantity of the servo motor at time t and the control input quantity of the servo motor at time t+1, predicting the physical state quantity of the servo motor at time t+n, the physical state quantity includes the position and speed of the servo motor, and the control input quantity is the acceleration of the servo motor, wherein t and n are any positive integers; based on the physical state quantity of the servo motor at time t and the predicted quantity of the physical state quantity at time t+n, outputting the control input quantity at the next moment that minimizes the sum of the preset servo motor influence factors, the influence factors include position following error, acceleration, and acceleration change rate. The method obtains the distance between the laser head and the processing surface in real time, and then realizes highly fast, stable and precise control through model predictive control, so the computing power requirement of the system is low, and it has strong real-time and robustness.

Description

Technical Field

[0001] The invention belongs to the field of numerical control machine tool control, and specifically relates to a five-axis laser follow-up control method based on model predictive control and an application thereof. Background Art

[0002] In recent years, with the continuous development and innovation of intelligent manufacturing technology, five-axis laser cutting technology has played an increasingly important role in various fields. This technology realizes multi-angle processing of workpieces by adding two rotating coordinate axes on the basis of three linear coordinate axes. This makes five-axis laser cutting technology more flexible in processing workpieces with complex surfaces and multi-layer structures.

[0003] Unlike traditional five-axis turning and milling machines, five-axis laser cutting technology requires real-time adjustment of the focal position of the laser head to achieve precise cutting and engraving of the workpiece surface, thereby meeting various precision processing needs. So, how to adjust the focal position of the laser head in real time during the five-axis processing so that the laser head can quickly track the workpiece surface and maintain a constant distance becomes the key to solving this problem. The existing technology pre-processes the processing NC program, analyzes the shape of the workpiece in advance and plans the corresponding path, thereby controlling the height of the laser head to remain constant with the processing surface. It is too dependent on the system computing power and has certain limitations in the processing of complex processes.

[0004] Therefore, in view of the above technical problems, it is necessary to provide an improved control method for a laser knife on a five-axis CNC machine tool.

[0005] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0006] The purpose of the present invention is to provide a five-axis laser follow-up control method based on model predictive control, which is applied to a five-axis CNC machine tool laser knife. It can achieve accurate and stable height control of the laser knife, has low requirements on system computing power, and has strong adaptability.

[0007] In order to achieve the above object, a technical solution provided by a specific embodiment of the present invention is as follows:

[0008] In a first aspect, the present invention provides a five-axis laser follow-up control method based on model predictive control, which is applied to a five-axis CNC machine tool laser tool, and comprises:

[0009] Based on the physical state quantity of the servo motor at time t and the control input quantity of the servo motor at time t+1, predict the physical state quantity of the servo motor at time t+n, the physical state quantity includes the position and speed of the servo motor, and the control input quantity is the acceleration of the servo motor, wherein t and n are any positive integers;

[0010] Based on the physical state quantity of the servo motor at time t and the predicted quantity of the physical state quantity at time t+n, the control input quantity at the next moment is output so that the sum of the preset servo motor influencing factors reaches the minimum, and the influencing factors include position following error, acceleration, and acceleration change rate.

[0011] In one or more embodiments of the present invention, the method further comprises:

[0012] respectively setting the weight value of each of the influencing factors;

[0013] Based on the influencing factors of each of the servo motors and the corresponding weight values, a performance index is constructed.

[0014] In one or more embodiments of the present invention, the performance indicator is:

[0015]

[0016] Among them, p target is the target position of the servo motor at the current moment, p t is the position of the servo motor at time t, a t is the acceleration of the servo motor at time t, is the accumulated position following error loss term of the system, is the acceleration loss term of the system, is the system’s acceleration rate loss term, W p is the weight value of the position following error loss term, W a is the weight value of the acceleration loss term, W Δa is the weight value of the acceleration change rate loss term.

[0017] In one or more embodiments of the present invention, the output of the control input quantity at the next moment that minimizes the sum of the preset servo motor influence factors includes:

[0018] Constructing constraint conditions based on the preset maximum speed and maximum acceleration of the servo motor;

[0019] The performance index is used as the objective function, and the control input quantity at each moment in the objective function is used as a variable. Based on the optimization algorithm, the value of the control input quantity at the next moment that minimizes the objective function is calculated and output.

[0020] In one or more embodiments of the present invention, the constraint condition is:

[0021] v t ∈[-v max , v max ]

[0022] a t ∈[-a max , a max ]

[0023] t∈{1,2,3....N}

[0024] Among them, v max is the preset maximum speed of the servo motor, a max It is the preset maximum acceleration of the servo motor.

[0025] In one or more embodiments of the present invention, the method further comprises:

[0026] Based on the length of the laser knife and the preset distance between the laser knife head and the processing surface, the total knife length of the laser knife is calculated, and the total knife length is the sum of the length of the laser knife and the preset distance between the laser knife head and the processing surface;

[0027] Based on the total tool length of the laser knife, the five-axis tool tip following function is enabled.

[0028] In one or more embodiments of the present invention, the method of predicting the physical state quantity of the servo motor at time t+n based on the physical state quantity of the servo motor at time t and the control input quantity of the servo motor at time t+1 includes:

[0029] At time t, predicting the speed value of the servo motor at time t+1 based on the speed value of the servo motor at time t and the speed change of the servo motor at time t+1;

[0030] At time t, the position of the servo motor at time t+1 is predicted based on the position of the servo motor at time t and the average position change of the servo motor at time t and time t+1.

[0031] In one or more embodiments of the present invention, the method of predicting the physical state quantity of the servo motor at time t+n based on the physical state quantity of the servo motor at time t and the control input quantity of the servo motor at time t+1 includes:

[0032] Based on a preset dynamic model, the physical state quantity of the servo motor at time t and the control input quantity of the servo motor at time t+1 are input, and the physical state quantity of the servo motor at time t+n is output;

[0033] The dynamic model is:

[0034] v t+1 =v t +a t+1 ·Δt

[0035] p t+1 =p t +0.5(v t +v t+1 )·Δt

[0036] Among them, v t is the speed of the servo motor at time t, p t is the position of the servo motor at time t, and Δt is the time interval between time t and time t+1.

[0037] In a second aspect, the present invention provides a five-axis laser follow-up control system based on model predictive control, which is applied to a five-axis CNC machine tool laser tool, and comprises:

[0038] A prediction module, used for predicting the physical state quantity of the servo motor at time t+n based on the physical state quantity of the servo motor at time t and the control input quantity of the servo motor at time t+1, wherein the physical state quantity includes the position and speed of the servo motor, and the control input quantity is the acceleration of the servo motor, wherein t and n are any positive integers;

[0039] The output module is used to output the control input quantity at the next moment so that the sum of the preset servo motor influencing factors reaches the minimum based on the physical state quantity of the servo motor at time t and the predicted quantity of the physical state quantity at time t+n, wherein the influencing factors include position following error, acceleration, and acceleration change rate.

[0040] In a third aspect, the present invention provides a computer device, comprising: a memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the five-axis laser follow-up control method based on model predictive control by executing the computer instructions.

[0041] In a fourth aspect, the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a computer to execute the five-axis laser follow-up control method based on model predictive control.

[0042] Compared with the prior art, the five-axis laser follow-up control method based on model predictive control provided by the present invention predicts the physical state quantity of the servo motor at multiple moments in the future based on the physical state quantity of the servo motor at the current moment, and outputs the control input quantity at the next moment when the sum of the servo motor position following error, acceleration, and acceleration change rate reaches the minimum based on the predicted quantity of the physical state quantity at multiple moments in the future, which can achieve high-speed, stable, and precise control, has low requirements on the computing power of the system, and has strong real-time and robustness. At the same time, the performance indicators and the weights of each item in the performance indicators can be freely configured based on different actual usage scenarios, so that the method has extremely strong flexibility and adaptability. Furthermore, based on the five-axis tool tip following function, the complex five-axis laser height control problem is simplified into a single-axis position control problem, which further reduces the calculation pressure and makes the present solution more concise. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0044] Figure 1 is a schematic diagram of a scenario of five-axis laser servo control based on model predictive control in one embodiment of the present invention;

[0045] Figure 2 It is a flow chart of a five-axis laser servo control method based on model predictive control in one embodiment of the present invention;

[0046] Figure 3 It is a structural block diagram of a five-axis laser servo control system based on model predictive control in one embodiment of the present invention;

[0047] Figure 4 is a structural block diagram of an electronic device in one embodiment of the present invention;

[0048] Figure 5 It is a schematic diagram of the arrangement of laser tools in one embodiment of the present invention. DETAILED DESCRIPTION

[0049] The specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific implementation modes.

[0050] Unless explicitly stated otherwise, throughout the specification and claims, the term “comprise” or variations such as “include” or “comprising”, etc., will be understood to include the stated elements or components but not to exclude other elements or components.

[0051] In order to facilitate understanding of the technical solutions of the present application, the technical terms that may appear in the present invention are first explained in detail below.

[0052] NC program (Numerical Control): Numerical control program is an automatic control technology developed in modern times. The national standard (GB8129-87) defines it as "a method of controlling the movement of machine tools and their processing processes with digital signals", referred to as CNC. CNC technology and CNC machine tools are one of the most important basic technologies for realizing flexible manufacturing (FM) and computer integrated manufacturing. CNC machine tools and their CNC equipment are the most basic processing units of manufacturing systems. With the continuous development and rapid application of microelectronics technology, computer technology, automatic control and precision measurement technology, in the manufacturing industry, CNC technology and CNC machine tools have long moved from research and development to practical use, and have been continuously updated and rapidly developed in the direction of high speed, multi-function, intelligence, openness and high reliability.

[0053] Five-axis tool tip following: For machine tools that include the RTCP function, RTCP detection can be used, that is, programming to keep the tool tip point stationary relative to the workpiece coordinate system, and the tool axis point moves according to the set trajectory. The five-axis linkage performance is reflected by detecting the offset of the tool tip point. The more common instruments are the R-test detectors composed of a ball head rod and a micrometer. RTCP, in high-end five-axis CNC systems, is considered to be the Rotated Tool Center Point, which is what we often call the tool tip point following function. In five-axis machining, when pursuing the tool tip point trajectory and the posture between the tool and the workpiece, the additional movement of the tool tip point is generated due to the rotational motion. The control point of the CNC system often does not coincide with the tool tip point, so the CNC system must automatically correct the control point to ensure that the tool tip point moves according to the specified trajectory of the instruction.

[0054] In the prior art, there is a method for controlling a laser tool, which specifically includes: preprocessing a machining NC program, wherein the NC program provides a way to organize tool paths in multiple settings into a CNC machine program group, which can optimize operations for a machine tool with multiple fixtures and fixture offsets. At the same time, the NC program can perform tool path simulation on any group. The group can include a single operation, an entire setting, or optimized operations in multiple settings. After parsing the shape of the workpiece and planning the corresponding path, the height of the laser head is controlled to remain constant with the machining surface, thereby achieving follow-up control of the laser tool.

[0055] It is understandable that the more complex the processing technology, the more complicated the NC program editing. At the same time, since the NC program is dependent on the system's computing power, as the processing technology becomes more complicated, the requirements for system computing power will become higher, which has limitations in actual production and processing. Therefore, this technical solution will inevitably have problems such as poor real-time and robustness, and it is difficult to operate stably in complex processing.

[0056] The inventor of the present invention discovered the main shortcomings of the prior art, and based on the shortcomings of the prior art, proposed a new technical implementation idea: using a height sensor to obtain the distance between the laser head and the processing surface in real time, predicting the physical state of the laser tool based on the model, and solving the optimal control signal of the laser tool at the next moment based on the physical state and the performance indicators of the system, that is, the optimal acceleration value of the servo motor at the next moment, thereby realizing the follow-up control of the laser tool. The follow-up control method using model prediction greatly reduces the demand for system computing power, making the method extremely real-time and robust, and can be stably implemented even in complex processing scenarios.

[0057] Please refer to Figure 1 , which is a schematic diagram of an application scenario of a five-axis laser follow-up control method based on model predictive control provided by the present invention under one embodiment, and the application scenario specifically includes: an interactive interface 101, a data processing module 102 and a servo motor 103.

[0058] It should be noted that a communication connection is provided between the interactive interface 101, the data processing module 102 and the servo motor 103, and the communication network corresponding to the communication connection may include various connection types, including but not limited to: wired connection, wireless connection or optical fiber cable connection, etc. At the same time, the communication network may be a local area network, a metropolitan area network, a wide area network or any combination of the three.

[0059] It is understandable that the user sets the prediction model for predicting the physical state quantity of the servo motor, the performance index for solving the optimal control quantity and the corresponding constraint conditions based on the interactive interface 101. At the same time, the interactive interface 101 can modify the influencing factors, the weight values ​​of different influencing factors, the relevant parameters of the prediction model, etc. as needed based on the needs of the actual application scenario. The interactive interface 101 should be able to use a computer software program that matches the five-axis laser follow-up control method based on model predictive control provided by the method.

[0060] Furthermore, since a communication connection is provided between the interactive interface 101, the data processing module 102 and the servo motor 103, the data processing module 102 can receive the prediction model of the servo motor physical state quantity set in the interactive interface 101, the performance index for solving the optimal control quantity and the corresponding constraint conditions, etc. At the same time, the physical state quantity of the servo motor and the laser tool fed back by the sensor on the servo motor 103 can be obtained. Then, based on the physical state quantity, the physical state quantity of the servo motor at multiple moments in the future is predicted, and the optimal control input quantity at the next moment is solved by the optimization algorithm through the preset performance index and constraint conditions, and the input quantity is sent to the servo motor.

[0061] The servo motor 103 is connected to a laser tool and a sensor device, which can detect the physical state of the servo motor and the laser tool in real time and feed it back to the server for data processing. The servo motor 103 receives the optimal control input at the next moment calculated by the server, and controls the laser tool based on the control input. Figure 5 The figure shows a schematic diagram of the arrangement of laser tools in one embodiment of the present invention, so that the laser focus of the laser tool is always located on the processing plane, that is, the laser head of the laser tool is always kept at a constant distance from the processing plane. First, the laser head height H is set, and then the system uses the sum of the laser head length L and the height H as the total tool length and enables the five-axis tool tip following function to plan the processing path based on this tool length; then, the complex five-axis laser height control problem is simplified to a single-axis (W-axis) position control problem.

[0062] Please refer to Figure 2 The figure is a flow chart of an embodiment of the present invention. The five-axis laser follow-up control method based on model predictive control specifically comprises the following steps:

[0063] S201: predicting the physical state of the servo motor at time t+n based on the physical state of the servo motor at time t+1 and the control input of the servo motor at time t+1;

[0064] It should be noted that the above-mentioned physical state quantity includes the position and speed of the servo motor, and the above-mentioned control input quantity is the acceleration of the servo motor, wherein t and n are any positive integers.

[0065] In an exemplary embodiment, the physical state quantity of the servo motor at time t+n is predicted based on the physical state quantity of the servo motor at time t and the control input quantity of the servo motor at time t+1, including: at time t, predicting the speed value of the servo motor at time t+1 based on the speed value of the servo motor at time t and the speed change of the servo motor at time t+1; at time t, predicting the position of the servo motor at time t+1 based on the position of the servo motor at time t and the average position change of the servo motor at time t and time t+1.

[0066] In a specific embodiment, based on a preset dynamic model, the physical state quantity of the servo motor at time t and the control input quantity of the servo motor at time t+1 are input, and the physical state quantity of the servo motor at time t+n is output;

[0067] Assuming that the time intervals between adjacent moments are the same, i.e., Δt, the above preset dynamic model can be:

[0068] v t+1 =v t +a t+1 ·Δt

[0069] p t+1 =p t +0.5(v t +v t+1 )·Δt

[0070] Among them, v t is the speed of the servo motor at time t, p t is the position of the servo motor at time t, and Δt is the time interval between time t and time t+1.

[0071] If the current time is t=2, the server obtains the physical state of the servo motor collected by the sensor in real time, that is, the speed v2 and position p2 of the servo motor at t=2. Based on the above known quantities, the physical state of the servo motor at any time in the future can be predicted based on the dynamic equation. For example:

[0072] v3=v2+a3·Δt

[0073] p3=p2+0.5(v2+v3)·Δt

[0074] v4=v3+a4·Δt=v2+a3·Δt+a4·Δt

[0075] p4=p3+0.5(v3+v4)·Δt=p2+0.5(v2+v3)·Δt+

[0076] 0.5(v2+a3·Δt+v2+a3·Δt+a4·Δt)·Δt ......

[0078] It should be noted that the control input a t It is used as a variable in the above dynamic equation and solved based on the optimization algorithm in the subsequent performance indicators.

[0079] S202: Based on the physical state quantity of the servo motor at time t and the predicted quantity of the physical state quantity at time t+n, output the control input quantity at the next moment that minimizes the sum of the preset servo motor influencing factors, where the influencing factors include position following error, acceleration, and acceleration change rate.

[0080] In an exemplary embodiment, the five-axis laser follow-up control method based on model predictive control also includes: setting the weight value of each influencing factor respectively; and constructing a performance index based on the influencing factor of each servo motor and the corresponding weight value.

[0081] It is understandable that in different production and processing environments, the impact of various influencing factors on the actual processing accuracy is different. Therefore, a weight value is set for each influencing factor. The larger the weight value, the greater the impact of the influencing factor on the system performance.

[0082] The further output makes the sum of the preset servo motor influencing factors reach the minimum control input at the next moment, including: constructing constraint conditions based on the preset maximum speed and maximum acceleration of the servo motor; taking the performance index as the objective function, taking the control input at each moment in the objective function as a variable, and calculating and outputting the value of the control input at the next moment that makes the objective function reach the minimum based on the optimization algorithm.

[0083] In a specific embodiment, the performance indicator may be:

[0084]

[0085] Among them, p target is the target position of the servo motor at the current moment, p t is the position of the servo motor at time t, a t is the acceleration of the servo motor at time t, is the accumulated position following error loss term of the system, is the acceleration loss term of the system, is the system’s acceleration rate loss term, W p is the weight value of the position following error loss term, W a is the weight value of the acceleration loss term, W Δa is the weight value of the acceleration rate loss term.

[0086] Using the above specific embodiment, if the current moment is t=2, the predicted physical state quantities and the target position of the servo motor at the current moment are brought into the above performance index equation, and the final performance index equation is: n(n∈3, 4, 5...., N) is the objective function of the variables. Based on the preset maximum speed and maximum acceleration of the servo motor for stable and normal operation as constraints, the optimization algorithm is used to calculate and output the value of the control input at the next moment that makes the objective function reach the minimum.

[0087] The optimization algorithm may be a linear programming algorithm, a quadratic programming algorithm, etc., which is not limited in the embodiment of the present invention.

[0088] It should be noted that the influencing factors can be changed according to different implementation scenarios. Similarly, in different real-time scenarios, the weights of the influencing factors can also be adaptively adjusted.

[0089] It should also be noted that the five-axis laser tracking control method based on model predictive control provided by the present invention also includes: calculating the total tool length of the laser tool based on the length of the laser tool and the preset distance between the laser tool head and the processing surface, the total tool length being the sum of the length of the laser tool and the preset distance between the laser tool head and the processing surface; and enabling the five-axis tool tip following function based on the total tool length of the laser tool.

[0090] Based on the five-axis tool tip following function, the complex five-axis laser height control problem is simplified into a single-axis position control problem, that is, it is transformed into a distance problem between the laser tool head and the processing surface.

[0091] Please refer to Figure 3 As shown, based on the same inventive concept as the aforementioned five-axis laser follow-up control method based on model predictive control, an embodiment of the present invention provides a five-axis laser follow-up control system 300 based on model predictive control, which includes: a prediction module 301 and an output module 302.

[0092] Specifically, the prediction module 301 is used to predict the physical state quantity of the servo motor at time t+n based on the physical state quantity of the servo motor at time t+1 and the control input quantity of the servo motor at time t+1, the physical state quantity including the position and speed of the servo motor, and the control input quantity including the acceleration of the servo motor, wherein t and n are any positive integers; the output module 302 is used to output the control input quantity at the next moment that minimizes the sum of the preset servo motor influencing factors based on the physical state quantity of the servo motor at time t and the predicted quantity of the physical state quantity at time t+n, the influencing factors including position following error, acceleration, and acceleration change rate.

[0093] It should be noted that the prediction module 301 is also used to predict the speed value of the servo motor at time t+1 based on the speed value of the servo motor at time t and the speed change of the servo motor at time t+1; at time t, predict the position of the servo motor at time t+1 based on the position of the servo motor at time t and the average position change of the servo motor at time t and time t+1.

[0094] The prediction module 301 is also used to input the physical state quantity of the servo motor at time t and the control input quantity of the servo motor at time t+1 based on a preset dynamic model, and output the physical state quantity of the servo motor at time t+n; the dynamic model is:

[0095] v t+1 =v t +a t+1 ·Δt

[0096] p t+1 =p t +0.5(v t +v t+1 )·Δt

[0097] Among them, v t is the speed of the servo motor at time t, p t is the position of the servo motor at time t, and Δt is the time interval between time t and time t+1.

[0098] The output module 302 is further used to set the weight value of each of the influencing factors respectively; and construct a performance index based on the influencing factors of each of the servo motors and the corresponding weight values.

[0099] The performance indicators are:

[0100]

[0101] Among the above performance indicators, p target is the target position of the servo motor at the current moment, p t is the position of the servo motor at time t, a t is the acceleration of the servo motor at time t, is the accumulated position following error loss term of the system, is the acceleration loss term of the system, is the system’s acceleration rate loss term, W p is the weight value of the position following error loss term, W a is the weight value of the acceleration loss term, W Δa is the weight value of the acceleration rate loss term.

[0102] The output module 302 is also used to construct constraint conditions based on the preset maximum speed and maximum acceleration of the servo motor; taking the performance index as the objective function, taking the control input quantity at each moment in the objective function as a variable, and based on the optimization algorithm, calculating and outputting the value of the control input quantity at the next moment that makes the objective function reach the minimum.

[0103] The constraints are:

[0104] v t ∈[-v max , v max ]

[0105] a t ∈[-a max , a max ]

[0106] t∈{1,2,3....N}

[0107] In the above constraints, v max is the preset maximum speed of the servo motor, a max It is the preset maximum acceleration of the servo motor.

[0108] It should also be noted that the five-axis laser tracking control system 300 based on model predictive control also includes a starting module, which is used to calculate the total tool length of the laser tool based on the length of the laser tool and the preset distance between the laser tool head and the processing surface, the total tool length being the sum of the length of the laser tool and the preset distance between the laser tool head and the processing surface; based on the total tool length of the laser tool, the five-axis tool tip following function is enabled.

[0109] Please refer to Figure 4 As shown, an embodiment of the present invention further provides an electronic device 400, which includes at least one processor 401, a memory 402 (such as a non-volatile memory), a memory 403, and a communication interface 404, and the at least one processor 401, the memory 402, the memory 403, and the communication interface 404 are connected together via a bus 405. At least one processor 401 is used to call at least one program instruction stored or encoded in the memory 402, so that the at least one processor 401 performs various operations and functions of the five-axis laser follow-up control method based on model predictive control described in various embodiments of this specification.

[0110] In an embodiment of the present specification, the electronic device 400 may include, but is not limited to, a personal computer, a server computer, a workstation, a desktop computer, a laptop computer, a notebook computer, a mobile electronic device, a smart phone, a tablet computer, a cellular phone, a personal digital assistant (PDA), a handheld device, a messaging device, a wearable electronic device, a consumer electronic device, and the like.

[0111] An embodiment of the present invention also provides a computer-readable medium, which carries computer execution instructions. When the computer execution instructions are executed by a processor, they can be used to implement various operations and functions of the five-axis laser tracking control method based on model predictive control described in the various embodiments of this specification.

[0112] The computer-readable medium in the present invention may be a computer-readable signal medium or a computer-readable storage medium or any combination of the above two. The computer-readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or device, or any combination of the above. More specific examples of computer-readable storage media may include, but are not limited to: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In the present invention, a computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in combination with an instruction execution system, device or device.

[0113] In the present invention, a computer-readable signal medium may include a data signal propagated in a baseband or as part of a carrier wave, which carries a computer-readable program code. Such propagated data signals may take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. A computer-readable signal medium may also be any computer-readable medium other than a computer-readable storage medium, which may send, propagate, or transmit a program for use by or in conjunction with an instruction execution system, device, or device. The program code contained on the computer-readable medium may be transmitted using any appropriate medium, including but not limited to: wireless, wire, optical cable, RF, etc., or any suitable combination of the above.

[0114] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0115] The present invention is described with reference to flowcharts and / or block diagrams of methods, apparatuses, systems, and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as a combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the process in the flowchart. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0116] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. The scope of the present invention is intended to be limited by the claims and their equivalents.

Claims

1. A five-axis laser follow-up control method based on model predictive control, applied to a five-axis CNC machine tool laser tool, characterized in that: include: Based on the physical state quantity of the servo motor at time t and the control input quantity of the servo motor at time t+1, predict the physical state quantity of the servo motor at time t+n, the physical state quantity includes the position and speed of the servo motor, and the control input quantity is the acceleration of the servo motor, wherein t and n are any positive integers; Based on the physical state quantity of the servo motor at time t and the predicted quantity of the physical state quantity at time t+n, output the control input quantity at the next moment that minimizes the sum of the preset servo motor influence factors, wherein the influence factors include position following error, acceleration, and acceleration change rate; The output makes the sum of the preset servo motor influence factors reach the minimum control input at the next moment, including: setting the weight value of each of the influence factors respectively; constructing a performance index based on the influence factor of each servo motor and the corresponding weight value; constructing a constraint condition based on the preset maximum speed and maximum acceleration of the servo motor; taking the performance index as the objective function, taking the control input at each moment in the objective function as a variable, and calculating and outputting the value of the control input at the next moment that makes the objective function reach the minimum based on the optimization algorithm.

2. The five-axis laser servo control method based on model predictive control according to claim 1, characterized in that: The performance indicators are: Among them, p target is the target position of the servo motor at the current moment, p t is the position of the servo motor at time t, a t is the acceleration of the servo motor at time t, is the accumulated position following error loss term of the system, is the acceleration loss term of the system, is the system's acceleration rate loss term, W p is the weight value of the position following error loss term, W a is the weight value of the acceleration loss term, W Δa is the weight value of the acceleration change rate loss term.

3. The five-axis laser servo control method based on model predictive control according to claim 1, characterized in that: The constraints are: v t ∈[-v max ,v max ] a t ∈[-a max ,a max ] t∈{1,2,3....N} Among them, v max is the preset maximum speed of the servo motor, a max It is the preset maximum acceleration of the servo motor.

4. The five-axis laser servo control method based on model predictive control according to claim 1, characterized in that: The method further comprises: Based on the length of the laser knife and the preset distance between the laser knife head and the processing surface, the total knife length of the laser knife is calculated, and the total knife length is the sum of the length of the laser knife and the preset distance between the laser knife head and the processing surface; Based on the total tool length of the laser knife, the five-axis tool tip following function is enabled.

5. The five-axis laser servo control method based on model predictive control according to claim 1, characterized in that: The method of predicting the physical state quantity of the servo motor at time t+n based on the physical state quantity of the servo motor at time t and the control input quantity of the servo motor at time t+1 includes: At time t, predicting the speed value of the servo motor at time t+1 based on the speed value of the servo motor at time t and the speed change of the servo motor at time t+1; At time t, the position of the servo motor at time t+1 is predicted based on the position of the servo motor at time t and the average position change of the servo motor at time t and time t+1.

6. The five-axis laser servo control method based on model predictive control according to claim 5, characterized in that: The method of predicting the physical state quantity of the servo motor at time t+n based on the physical state quantity of the servo motor at time t and the control input quantity of the servo motor at time t+1 includes: Based on a preset dynamic model, the physical state quantity of the servo motor at time t and the control input quantity of the servo motor at time t+1 are input, and the physical state quantity of the servo motor at time t+n is output; The dynamic model is: v t+1 =v t +a t+1 ·Δt p t+1 =p t +0.5(v t +v t+1 )·Δt Among them, v t is the speed of the servo motor at time t, p t is the position of the servo motor at time t, and Δt is the time interval between time t and time t+1.

7. A five-axis laser servo control system based on model predictive control, applied to five-axis CNC machine tool laser tools, characterized in that: include: A prediction module, used for predicting the physical state quantity of the servo motor at time t+n based on the physical state quantity of the servo motor at time t and the control input quantity of the servo motor at time t+1, wherein the physical state quantity includes the position and speed of the servo motor, and the control input quantity is the acceleration of the servo motor, wherein t and n are any positive integers; An output module, for outputting a control input quantity at the next moment that minimizes the sum of preset servo motor influence factors based on the physical state quantity of the servo motor at time t and the predicted quantity of the physical state quantity at time t+n, wherein the influence factors include position following error, acceleration, and acceleration change rate; The output makes the sum of the preset servo motor influence factors reach the minimum control input at the next moment, including: setting the weight value of each of the influence factors respectively; constructing a performance index based on the influence factor of each servo motor and the corresponding weight value; constructing a constraint condition based on the preset maximum speed and maximum acceleration of the servo motor; taking the performance index as the objective function, taking the control input at each moment in the objective function as a variable, and calculating and outputting the value of the control input at the next moment that makes the objective function reach the minimum based on the optimization algorithm.

8. A computer device, characterized in that: include: A memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the five-axis laser follow-up control method based on model predictive control as described in any one of claims 1 to 7 by executing the computer instructions.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a computer to execute the five-axis laser follow-up control method based on model predictive control according to any one of claims 1 to 7.

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