LDI machine self-calibration system and method based on bistable bionic compliant mechanism

Abstract

The invention relates to the technical field of calibration devices, in particular to an LDI machine self-calibration system and method based on a bistable bionic compliant mechanism, the LDI machine self-calibration system comprises a base, a motion control platform, a portal frame assembly, a visual calibration assembly and a control system, and the motion control platform, the portal frame assembly and the control system are all connected with the base; the portal frame assembly is provided with a sliding rail, the visual calibration assembly comprises a fixed bottom plate in sliding connection with the sliding rail, a camera module arranged on the fixed bottom plate and a bistable focusing module connected with the camera module, and the bistable focusing module can achieve rapid switching between a first stable position and a second stable position. The control system is in signal connection with the motion control platform and the visual calibration assembly and adjusts the position of the motion control platform according to signals of the visual calibration assembly. The positioning precision of the calibration system is remarkably improved, the calibration error is reduced, and the method is suitable for high-precision machining occasions.

Description

Technical Field

[0001] The present invention relates to the technical field of calibration devices, and more specifically, to an LDI machine self-calibration system and method based on a bistable bionic compliant mechanism. Background Art

[0002] As one of the core technologies for printed circuit board (PCB) manufacturing, laser direct imaging (LDI) technology has been widely used in the manufacturing of traditional and high-density PCBs due to its advantages such as no need for mask plates, high pattern resolution, and fast processing speed. In the LDI system, calibration and focusing are key links to ensure processing accuracy. However, as modern electronic equipment continues to increase its requirements for circuit board size, line width, and complexity, traditional LDI equipment has gradually exposed technical bottlenecks and is unable to meet the needs of sub-micron high-precision processing.

[0003] In the prior art, for example, Chinese patent CN 206292868U discloses a calibration device for an LDI alignment camera, comprising: a movable stage, a first camera, a second camera, a calibration component, a bracket and a moving mechanism; the first camera and the second camera are arranged on the bracket, and the viewfinders of the first camera and the second camera face the stage; the calibration component is detachably mounted on the surface of the stage; a moving mechanism is arranged at the bottom of the stage, and a base for supporting the moving mechanism and the bracket is arranged at the bottom of the moving mechanism; the first camera, the second camera and the moving mechanism are electrically connected to a controller respectively. However, the calibration method in this scheme usually relies on a mechanical adjustment mechanism and a single linear focusing method. Although these systems have certain stability, due to the existence of factors such as mechanical vibration, repeated positioning errors and environmental disturbances, it is often difficult to achieve ideal results in high-precision calibration scenarios. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art that the positioning accuracy is low and it is difficult to meet the needs of high-precision processing. A self-calibration system and method for an LDI machine based on a bistable bionic compliant mechanism is provided to achieve fast and stable focusing, reduce calibration errors, and is suitable for high-precision processing occasions.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] Provided is an LDI machine self-calibration system based on a bistable bionic compliant mechanism, comprising a base, a motion control platform, a gantry assembly, a visual calibration assembly and a control system, wherein the motion control platform, the gantry assembly and the control system are all connected to the base, the motion control platform comprises a work surface movable along an X-axis, a Y-axis and a Z-axis, the visual calibration assembly is used to collect spatial position information of calibration points on the work surface, the gantry assembly is provided with a slide rail, the visual calibration assembly comprises a fixed base plate slidably connected to the slide rail, a camera module arranged on the fixed base plate and a bistable focusing module connected to the camera module, the bistable focusing module can realize rapid switching between a first stable position and a second stable position, the control system is connected to the motion control platform and the visual calibration assembly by signal, and the control system adjusts the position of the motion control platform according to the signal of the visual calibration assembly.

[0007] The LDI machine self-calibration system based on the bistable bionic compliant mechanism of the present invention fixes the positions of the motion control platform, the gantry assembly and the control system through a base, so as to support the structure of the entire system and provide a stable operation basis. During the calibration process, the control system controls the visual calibration assembly to move on the gantry assembly, so that the visual calibration assembly is aligned with the work surface, and the spatial position information of each calibration point on the work surface is collected. According to the spatial position information of the calibration point, the bistable focusing module quickly switches between the first stable position and the second stable position, and adjusts the focal position of the camera module connected thereto. At the same time, the control system adjusts the position of the motion control platform in the X-axis, Y-axis and Z-axis directions according to the signal of the visual calibration assembly, so as to achieve stable and fast high-precision focusing, reduce the calibration error, and is suitable for high-precision processing occasions.

[0008] Furthermore, the bistable focusing module also includes a driving module and a bionic compliance module arranged on the fixed base plate, the driving module is connected to the bionic compliance module, and the bionic compliance module is connected to the camera module. The driving module drives the bionic compliance module to achieve rapid displacement adjustment, and works with the bionic compliance module to further optimize the stiffness adjustment curve and energy utilization efficiency during the switching process. The bionic compliance module enhances the overall stiffness of the compliance mechanism and improves the switching accuracy and stability by imitating the characteristics of the ligament having no force in a relaxed state and generating force in a taut state.

[0009] Furthermore, the bionic compliant module includes a fixing part, a first compliant beam, a rigid beam, a second compliant beam, a connecting part, and an output part for connecting to a camera module, wherein the driving module is connected to the connecting part, the two ends of the first compliant beam are respectively connected to the fixing part and the first connecting part, the two ends of the second compliant beam are respectively connected to the first connecting part and the connecting part, and the output part is connected to the connecting part. The fixing part ensures the stability of the bionic compliant module during high-frequency use, the driving module inputs the displacement to the connecting part, and the connecting part transmits the displacement to the first compliant beam during the switching process, the first compliant beam plays a role of energy storage and release during the switching process through its flexible deformation, the second compliant beam plays a role of rigid support during the entire switching movement, and prevents the system from bending and deforming the overall structure, the rigid beam connects the first flexible beam and the second compliant beam to form a closed-loop structure, and the overall structural performance of the system can be optimized by adjusting the first and second compliant beams on both sides of the rigid beam, the bionic compliant module as a whole uses the bistable characteristics to achieve smooth switching from the first stable position to the second stable position, and finally transmits the displacement to the camera module through the output part to achieve dynamic focusing.

[0010] Furthermore, the length of the first compliant beam is greater than the length of the second compliant beam, and the thickness of the first compliant beam is less than the thickness of the second compliant beam. The first compliant beam is designed to be long and thin, and is designed to withstand tension, and can avoid bending instability during dynamic movement; the second compliant beam is shorter and thicker than the first compliant beam, and mainly bears compression loads. The second compliant beam plays a role of rigid support in the entire switching movement, preventing the system from experiencing flexural deformation of the overall structure.

[0011] Furthermore, the fixing parts are symmetrically arranged on both sides of the connecting part, and multiple groups of first compliant beams, rigid beams and second compliant beams are arranged between the fixing parts and the connecting part. The symmetrically arranged fixing parts help to maintain the dynamic balance of the system and reduce the energy loss during the switching process. By arranging multiple groups of first compliant beams, rigid beams and second compliant beams, the force-displacement characteristic curve and the stiffness-displacement characteristic curve of the bionic compliant module can be adjusted to meet different calibration requirements.

[0012] The present invention also provides a LDI machine self-calibration method based on a bistable bionic compliant mechanism, comprising:

[0013] S1, workbench initialization: the motion control platform controls the workbench surface to move to an initial reference position;

[0014] S2, visual calibration data acquisition: the bistable focusing module quickly switches between the first stable position and the second stable position to adjust the focus position of the visual calibration component, so as to obtain a clear work surface image; the visual calibration component detects the spatial position of the calibration point on the work surface and records the real-time spatial coordinates of each calibration point;

[0015] S3, calibration error calculation: the control system calculates the calibration error according to the real-time spatial coordinates of each calibration point collected by the visual calibration component and the ideal spatial coordinates of each calibration point stored in the control system;

[0016] S4, error compensation: if the calibration error is greater than a set threshold, the control system calculates a compensation parameter according to the calibration error, and adjusts the position of the motion control platform according to the compensation parameter to correct the coordinate deviation of the work surface;

[0017] S5. Repeat calibration verification: the LDI machine self-calibration system repeatedly executes S2, S3, and S4 until the error of each calibration point is less than the set threshold.

[0018] The LDI machine self-calibration method based on the bistable bionic compliant mechanism of the present invention first initializes the workbench, moves the workbench to the initial reference position through the motion control platform, and during the acquisition process, the bistable compliant focusing module switches the first stable position and the second stable position to achieve rapid focusing and fine adjustment, dynamically adjusts the focus position of the camera, eliminates the acquisition error caused by defocus, and makes the image of the workbench clear, and then collects the real-time spatial position of each calibration point on the workbench through the visual calibration component, and the real-time spatial position information of the calibration point collected is input into the control system according to the error data of the real-time spatial position information, and the control system calculates the error compensation value through the error compensation algorithm, and transmits the information to the motion control platform, and the motion control platform adjusts the position of the workbench according to the command of the control system, and repeats the above process many times until the error of each calibration point is less than the set threshold. The present invention further optimizes the calibration accuracy by real-time monitoring and adjusting the position of the motion control platform, optimizing the calibration error data acquisition process and the error compensation algorithm, and ensuring that the requirements of high-precision automatic calibration are met.

[0019] Preferably, in step S3, the calculation of the calibration error includes the following steps: calculating the X-axis direction error: the X-axis direction error is determined by the X-axis grating scale error, the Y-axis and X-axis coupling error, the Z-axis error, and the perpendicularity error between the X-axis and the Y-axis; calculating the Y-axis direction error: the Y-axis direction error is determined by the Y-axis grating scale error, the Y-axis and Z-axis coupling error, the Z-axis error, and the perpendicularity error between the X-axis and the Y-axis. The LDI machine is provided with grating scales for measuring the linear displacement of the motion control platform in the X-axis, Y-axis, and Z-axis directions. The X-axis direction error is calculated by the X-axis grating scale error, the Y-axis and X-axis coupling error, the Z-axis error, and the perpendicularity error between the X-axis and the Y-axis. The Y-axis direction error is calculated by the Y-axis grating scale error, the Y-axis and Z-axis coupling error, the Z-axis error, and the perpendicularity error between the X-axis and the Y-axis.

[0020] Preferably, in step S4, the calculation of compensation parameters includes the following steps: the control system divides the calibration area into several grids, and uses an interpolation algorithm to calculate the error value of each grid point; based on the grid point error value, the control system obtains the optimized compensation parameters by dynamically optimizing the objective function. In the error compensation process, the calibration area is first divided into M×N grids, a compensation parameter set for each grid point is defined, and the error value of each grid point is obtained by interpolation calculation to ensure the continuity of the error between grids. During the calibration process, the control system corrects the difference between the actual coordinates and the ideal coordinates of the calibration point, and inputs the grid point error value into the dynamic optimization objective function to obtain the optimal solution of the compensation parameter.

[0021] Preferably, in step S4, the error compensation includes dynamic temperature compensation for avoiding the influence of thermal expansion and dynamic vibration compensation for avoiding the influence of mechanical disturbance. A temperature sensor is provided to provide real-time data of ambient temperature for dynamic temperature compensation, which is used to compensate for the influence of thermal expansion of the grating ruler and avoid error accumulation caused by temperature changes. A vibration detection module is provided to perform dynamic vibration compensation, identify mechanical disturbances that may occur during operation, and reduce their influence on calibration accuracy through dynamic compensation.

[0022] Preferably, it also includes S6: after repeated calibration verification is completed, the control system stores the optimized calibration parameters in a database and generates a calibration report. The control system generates a calibration report, which includes calibration point error distribution, compensation parameters and calibration accuracy analysis, and is stored in the database for direct call and research and analysis in subsequent work processes.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. Significantly improve the dynamic anti-disturbance capability of the calibration system, reduce the calibration error, and is suitable for high-precision processing occasions;

[0025] 2. The focusing response is fast and the energy consumption is low during steady-state switching, which ensures high calibration accuracy without increasing energy consumption;

[0026] 3. It can dynamically correct the deviations caused by environmental vibration and temperature fluctuations to ensure the long-term stability of calibration parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural diagram of the LDI machine self-calibration system based on the bistable bionic compliant mechanism;

[0028] Figure 2 It is a structural diagram of the visual calibration component;

[0029] Figure 3 It is the structural schematic diagram of the bionic compliant module;

[0030] Figure 4 is the force-displacement characteristic curve of the bionic compliant module;

[0031] Figure 5 is the stiffness-displacement characteristic curve of the bionic compliant module;

[0032] Figure 6 The figure is a flow chart of the LDI machine self-calibration method based on the bistable bionic compliant mechanism.

[0033] In the accompanying drawings: 100, base; 200, motion control platform; 210, work surface; 300, gantry assembly; 310, slide rail; 400, visual calibration assembly; 410, fixed bottom plate; 420, camera module; 430, bistable focusing module; 431, drive module; 432, bionic compliant module; 4321, fixing part; 4322, first compliant beam; 4323, rigid beam; 4324, second compliant beam; 4325, connecting part; 4326, output part. DETAILED DESCRIPTION

[0034] The present invention is further described below in conjunction with specific implementation methods. The accompanying drawings are only used for exemplary descriptions and are only schematic diagrams, not actual drawings, and cannot be understood as limiting this patent; in order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the accompanying drawings may be omitted.

[0035] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the drawings, it is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limitations on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0036] Embodiment 1

[0037] The present embodiment is the first embodiment of the LDI machine self-calibration system based on the bistable bionic compliant mechanism, which includes a base 100, a motion control platform 200, a gantry assembly 300, a visual calibration assembly 400 and a control system. The motion control platform 200, the gantry assembly 300 and the control system are all connected to the base 100. The motion control platform 200 includes a work surface 210 that can move along the X-axis, Y-axis and Z-axis directions. The visual calibration assembly 400 is used to collect the spatial position information of the calibration points on the work surface 210. The gantry assembly 300 is provided with a slide rail 310, and the visual calibration component 400 includes a fixed base plate 410 slidably connected to the slide rail 310, a camera module 420 arranged on the fixed base plate 410, and a bistable focusing module 430 connected to the camera module 420, the bistable focusing module 430 can realize rapid switching between a first stable position and a second stable position, the control system is connected with the motion control platform 200 and the visual calibration component 400 by signal, and the control system adjusts the position of the motion control platform 200 according to the signal of the visual calibration component 400.

[0038] The LDI machine self-calibration system based on the bistable bionic compliant mechanism in this embodiment is as follows: Figure 1 As shown, the motion control platform 200, the gantry assembly 300 and the control system are fixed by the base 100 to support the structure of the entire system and provide a stable operating basis. During the calibration process, the control system controls the visual calibration assembly 400 to move on the gantry assembly 300, so that the visual calibration assembly 400 is aligned with the work surface 210, and the spatial position information of each calibration point on the work surface 210 is collected. According to the spatial position information of the calibration point, the bistable focusing module 430 quickly switches between the first stable position and the second stable position, and adjusts the focus position of the camera module 420 connected thereto. At the same time, the control system adjusts the position of the motion control platform 200 in the X-axis, Y-axis and Z-axis directions according to the signal of the visual calibration assembly 400, so as to achieve stable and fast high-precision focusing, reduce calibration errors, and is suitable for high-precision processing occasions.

[0039] like Figure 4 As shown, the bistable focusing module 430 in this embodiment can maintain balance in two different positions without the action of external force, namely the first stable position and the second stable position. The bistable focusing module 430 in this embodiment has two local minima in the energy potential function, corresponding to the first stable position and the second stable position, respectively. There is an energy barrier between the first stable position and the second stable position, which prevents the bistable focusing module 430 from sliding directly from the first stable position to the second stable position. When the driving module 431 applies a certain external force to enable the bionic compliance module 432 to cross the energy barrier, the bionic compliance module 432 will enter the second stable position from the first stable position, corresponding to another lowest potential energy state.

[0040] The bistable focusing module 430 further includes a driving module 431 and a bionic compliance module 432 disposed on the fixed base plate 410. The driving module 431 is connected to the bionic compliance module 432, and the bionic compliance module 432 is connected to the camera module 420. Figure 2 As shown, the driving module 431 drives the bionic compliance module 432 to achieve rapid displacement adjustment, and works together with the bionic compliance module 432 to further optimize the stiffness adjustment curve and energy utilization efficiency during the switching process. The bionic compliance module 432 imitates the characteristics of the ligament that has no force in a relaxed state and generates force in a taut state, thereby enhancing the overall stiffness of the compliance mechanism and improving the switching accuracy and stability.

[0041] The bionic compliance module 432 includes a fixing member 4321, a first compliance beam 4322, a rigid beam 4323, a second compliance beam 4324, a connecting member 4325, and an output member 4326 for connecting to the camera module 420. The driving module 431 is connected to the connecting member 4325. The two ends of the first compliance beam 4322 are respectively connected to the fixing member 4321 and the first connecting member 4325. The two ends of the second compliance beam 4324 are respectively connected to the first connecting member 4325 and the connecting member 4325. The output member 4326 is connected to the connecting member 4325. Figure 3As shown, the fixing member 4321 ensures the stability of the bionic compliant module 432 during high-frequency use, the driving module 431 inputs the displacement to the connecting member 4325, and the connecting member 4325 transmits the displacement to the first compliant beam 4322 during the switching process. The first compliant beam 4322 plays a role of energy storage and release during the switching process through its flexible deformation. The second compliant beam 4324 plays a role of rigid support in the entire switching movement to prevent the system from experiencing flexural deformation of the overall structure. The rigid beam 4323 connects the first flexible beam and the second compliant beam 4324 to form a closed-loop structure. By adjusting the first compliant beam 4322 and the second compliant beam 4324 on both sides of the rigid beam 4323, the overall structural performance of the system can be optimized. The bionic compliant module 432 as a whole utilizes the bistable characteristics to achieve smooth switching from the first stable position to the second stable position, and finally transmits the displacement to the camera module 420 through the output member 4326 to achieve dynamic focusing.

[0042] In order to reduce the energy consumption during the switching process, the length of the first compliant beam 4322 in this embodiment is greater than the length of the second compliant beam 4324, and the thickness of the first compliant beam 4322 is less than the thickness of the second compliant beam 4324, thereby reducing the input power required for the switching. The fixing member 4321 is symmetrically arranged on both sides of the connecting member 4325, and multiple groups of first compliant beams 4322, rigid beams 4323 and second compliant beams 4324 are arranged between the fixing member 4321 and the connecting member 4325.

[0043] like Figure 4 As shown in the curve, the design of the compliant beam reduces the peak value of the energy barrier, ensuring that lower mechanical energy is consumed when achieving bistable switching. The driving module 431 in this embodiment adopts a voice coil motor module and is equipped with a corrugated reed. The corrugated reed is installed on the supporting structure of the voice coil driving module 431, and provides additional support force through elastic deformation to offset the gravity of the voice coil motor itself and related structures, thereby reducing the driving force burden. The voice coil driving module 431 provides appropriate thrust when the predetermined displacement is reached, thereby optimizing the overall energy utilization efficiency. By adjusting the force output in real time, the voice coil driver significantly reduces the energy consumption in vibration compensation. In the dynamic focusing and steady-state switching scenarios, the voice coil driving module 431 and the bionic compliant module 432 form an efficient collaboration. The symmetrical structural design greatly improves the dynamic balance performance during the switching process, makes the working process smoother, and reduces internal energy losses. As Figure 4 As shown in FIG. 1 , the system has a nonlinear force-displacement relationship curve in the steady state. Certain energy barriers need to be overcome during the switching process, but the energy consumption can be reduced by optimizing the geometric parameters and material properties of the compliant beam. The optimized first compliant beam 4322 and the second compliant beam 4324 ensure that the system has higher efficiency and stability during switching. The stiffness-displacement characteristics are shown in FIG. Figure 5As shown in the figure, near the steady state, the system exhibits high stiffness characteristics, which enables it to quickly return to the steady state position under external disturbances. The stiffness in the middle area is relatively low, which helps to reduce input power consumption and improve the overall operating efficiency of the system.

[0044] The working principle of the LDI machine self-calibration system based on the bistable bionic compliant mechanism of this embodiment is as follows: during the calibration process, the control system controls the visual calibration component 400 to move on the gantry component 300, so that the visual calibration component 400 is aligned with the work surface 210, and the spatial position information of each calibration point on the work surface 210 is collected. According to the spatial position information of the calibration point, the bistable focusing module 430 quickly switches between the first stable position and the second stable position, and adjusts the focus position of the camera module 420 connected thereto. At the same time, the control system adjusts the position of the motion control platform 200 in the X-axis, Y-axis, and Z-axis directions according to the signal of the visual calibration component 400, so as to achieve stable and fast high-precision focusing.

[0045] Embodiment 2

[0046] This embodiment is the first embodiment of the LDI machine self-calibration method based on the bistable bionic compliant mechanism, including S1, workbench initialization: the motion control platform 200 controls the workbench surface 210 to move to an initial reference position;

[0047] S2, visual calibration data acquisition: the bistable focusing module 430 quickly switches between the first stable position and the second stable position to adjust the focus position of the visual calibration component 400, so as to obtain a clear image of the work surface 210; the visual calibration component 400 detects the spatial position of the calibration point on the work surface 210 and records the real-time spatial coordinates of each calibration point;

[0048] S3, calibration error calculation: the control system calculates the calibration error according to the real-time spatial coordinates of each calibration point collected by the visual calibration component 400 and the ideal spatial coordinates of each calibration point stored in the control system;

[0049] S4, error compensation: if the calibration error is greater than the set threshold, the control system calculates the compensation parameter according to the calibration error, and adjusts the position of the motion control platform 200 according to the compensation parameter to correct the coordinate deviation of the work surface 210;

[0050] S5. Repeat calibration verification: The LDI machine self-calibration system repeats S2, S3, and S4 until the error of each calibration point is less than the set threshold.

[0051] like Figure 6As shown, the LDI machine self-calibration method based on the bistable bionic compliant mechanism in this embodiment first initializes the workbench, and moves the worktable 210 to the initial reference position through the motion control platform 200. During the acquisition process, the bistable compliant focusing module switches the first stable position and the second stable position to achieve fast focusing and fine adjustment, dynamically adjust the focus position of the camera, eliminate the acquisition error caused by defocus, and make the image of the worktable 210 clear. Subsequently, the real-time spatial position of each calibration point on the worktable 210 is acquired through the visual calibration component 400, and the real-time spatial position information of the calibration point is acquired, and the error data of the real-time spatial position information is input into the control system. The control system calculates the error compensation value through the error compensation algorithm and transmits the information to the motion control platform 200. The motion control platform 200 adjusts the position of the worktable 210 according to the instruction of the control system, and the above process is repeated many times until the error of each calibration point is less than the set threshold. The present invention optimizes the calibration error data acquisition process and the error compensation algorithm by real-time monitoring and adjusting the position of the motion control platform 200, further optimizes the calibration accuracy, and ensures that the requirements of high-precision automatic calibration are met.

[0052] This embodiment also includes S6: after repeated calibration verification is completed, the control system stores the optimized calibration parameters in a database and generates a calibration report. The control system generates a calibration report, which includes calibration point error distribution, compensation parameters and calibration accuracy analysis, and is stored in the database for direct call and research and analysis in subsequent work processes.

[0053] In step S4 of this embodiment, error compensation includes dynamic temperature compensation for avoiding the influence of thermal expansion and dynamic vibration compensation for avoiding the influence of mechanical disturbance. A temperature sensor is provided to provide real-time data of ambient temperature for dynamic temperature compensation, which is used to compensate for the influence of thermal expansion of the grating ruler and avoid error accumulation caused by temperature changes. A vibration detection module is provided for dynamic vibration compensation to identify mechanical disturbances that may occur during operation and reduce their influence on calibration accuracy through dynamic compensation.

[0054] The working principle of the LDI machine self-calibration method based on the bistable bionic compliant mechanism in this embodiment is as follows: first, the workbench is initialized, and the workbench 210 is moved to the initial reference position through the motion control platform 200. During the acquisition process, the bistable compliant focusing module switches the first stable position and the second stable position to achieve fast focusing and fine adjustment, dynamically adjust the focus position of the camera, eliminate the acquisition error caused by defocus, and make the image of the workbench 210 clear. Subsequently, the real-time spatial position of each calibration point on the workbench 210 is acquired through the visual calibration component 400, and the real-time spatial position information of the acquired calibration point is input into the control system according to the error data of the real-time spatial position information. The control system calculates the error compensation value through the error compensation algorithm and transmits the information to the motion control platform 200. The motion control platform 200 adjusts the position of the workbench 210 according to the instruction of the control system, and the above process is repeated many times until the error of each calibration point is less than the set threshold. The present invention optimizes the calibration error data acquisition process and the error compensation algorithm by real-time monitoring and adjusting the position of the motion control platform 200, further optimizes the calibration accuracy, and ensures that the requirements of high-precision automatic calibration are met.

[0055] Embodiment 3

[0056] This embodiment is a second embodiment of the LDI machine self-calibration method based on a bistable bionic compliant mechanism. This embodiment is similar to the first embodiment, except that in step S3, calculating the calibration error includes the following steps:

[0057] Calculate the X-axis direction error: The X-axis direction error is determined by the X-axis grating scale error, the Y-axis and X-axis coupling error, the Z-axis error, and the perpendicularity error between the X-axis and the Y-axis;

[0058] Calculate the Y-axis direction error: The Y-axis direction error is determined by the Y-axis grating scale error, the Y-axis and Z-axis coupling error, the Z-axis error, and the perpendicularity error between the X-axis and the Y-axis.

[0059] The LDI machine is equipped with grating rulers in the X-axis, Y-axis and Z-axis directions for measuring the linear displacement of the motion control platform 200, and can automatically read the grating ruler errors in the directions of each coordinate axis.

[0060] Assume the actual coordinates of the platform are (X ij ,Y ij ), the theoretical coordinates are The relationship between the two can be expressed as:

[0061]

[0062] Among them, Δ x and Δ y They are the errors in the X-axis and Y-axis directions, which are further decomposed into:

[0063] Δ x =D xx +D xy ·yD zx ·z+T xy ·x

[0064] Δ y =D yy +D zy ·yD zx ·z+T xy ·y

[0065] Where x, y, and z represent the ideal coordinate values ​​of the calibration point in the X-axis, Y-axis, and Z-axis directions; D xx The deviation between the actual value of the X-coordinate of the calibration point in the X-axis direction and the ideal value, that is, the X-axis grating error; D xy D is the deviation between the actual value and the ideal value of the Y coordinate of the calibration point in the X-axis direction. xy y is the coupling error between the Y axis and the X axis; -D zx z is the Z-axis error; T xy x is the perpendicularity error between the X-axis and the Y-axis;

[0066] D yy The deviation between the actual value of the Y coordinate of the calibration point in the Y-axis direction and the ideal value, that is, the Y-axis grating error; D zy z is the deviation between the actual value and the ideal value of the Y coordinate of the calibration point in the Z-axis direction, D zy y is the coupling error between the Y-axis and the Z-axis.

[0067] According to the calibration data, the spatial deviation of the calibration point is matched with the error model to generate a calibration error matrix, which can be used for subsequent error interpolation calculation.

[0068] In step S4 of this embodiment, calculating the compensation parameters includes the following steps: the control system divides the calibration area into several grids, and uses the interpolation algorithm to calculate the error value of each grid point; based on the grid point error value, the control system obtains the optimized compensation parameters by dynamically optimizing the objective function. The calibration area is divided into M×N grids, and the compensation parameter set of each grid point is defined. The compensation parameters are obtained by interpolation calculation of the calibration points to ensure the continuity of the errors between the grids.

[0069] Error interpolation calculation is to interpolate the error value of each grid point. The interpolation formula is as follows:

[0070] Δ x =(1-α)·D xx +α·D xx +1+(1-β)·D yx +β·D yx+1

[0071] Δ y =(1-α)·D yy +α·D yy +1+(1-β)·D zy +β·D zy+1

[0072] Where (1-α) and α represent the distance ratio between the point and the left and right sides of the grid respectively; (1-β) and β represent the distance ratio between the point and the bottom and top of the grid respectively. α and β represent the interpolation weights, and their value range is [0,1].

[0073] During the calibration process, the system corrects the difference between the actual coordinates and the ideal coordinates of the calibration point by optimizing the objective function and establishing the following formula:

[0074]

[0075] The above formula is organized into a matrix form for further solution:

[0076]

[0077] The goal of the matrix Σ is to minimize the sum of squared errors, that is:

[0078]

[0079] By solving the inverse matrix of the above matrix, the optimal solution of the compensation parameters is obtained.

[0080] The working principle of the LDI machine self-calibration method based on the bistable bionic compliant mechanism in this embodiment is as follows: the collected calibration error data is input into the control system, the control system calculates the X-axis direction error and the Y-axis direction error, and calculates the optimal solution of the compensation parameters through error interpolation calculation and optimization objective function.

[0081] In the specific contents of the above-mentioned specific implementation methods, the various technical features can be combined in any non-contradictory manner. In order to make the description concise, not all possible combinations of the above-mentioned technical features are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0082] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. An LDI machine self-calibration system based on a bistable bionic compliant mechanism, characterized in that: The invention comprises a base (100), a motion control platform (200), a gantry assembly (300), a visual calibration assembly (400) and a control system, wherein the motion control platform (200), the gantry assembly (300) and the control system are all connected to the base (100), the motion control platform (200) comprises a work surface (210) movable along an X-axis, a Y-axis and a Z-axis, the visual calibration assembly (400) is used to collect spatial position information of calibration points of the work surface (210), the gantry assembly (300) is provided with a slide rail (310), and the visual calibration assembly (400) is used to collect spatial position information of calibration points of the work surface (210). The component (400) comprises a fixed base plate (410) slidably connected to the slide rail (310), a camera module (420) arranged on the fixed base plate (410), and a bistable focusing module (430) connected to the camera module (420), wherein the bistable focusing module (430) can realize rapid switching between a first stable position and a second stable position, and the control system is connected to the motion control platform (200) and the visual calibration component (400) by signal, and the control system adjusts the position of the motion control platform (200) according to the signal of the visual calibration component (400).

2. The LDI machine self-calibration system based on the bistable bionic compliant mechanism according to claim 1 is characterized in that: The bistable focusing module (430) further comprises a driving module (431) and a bionic compliance module (432) arranged on the fixed base plate (410); the driving module (431) is connected to the bionic compliance module (432); and the bionic compliance module (432) is connected to the camera module (420).

3. The LDI machine self-calibration system based on the bistable bionic compliant mechanism according to claim 2 is characterized in that: The bionic compliant module (432) comprises a fixing member (4321), a first compliant beam (4322), a rigid beam (4323), a second compliant beam (4324), a connecting member (4325), and an output member (4326) for connecting to a camera module (420); the driving module (431) is connected to the connecting member (4325); two ends of the first compliant beam (4322) are respectively connected to the fixing member (4321) and the first connecting member (4325); two ends of the second compliant beam (4324) are respectively connected to the first connecting member (4325) and the connecting member (4325); and the output member (4326) is connected to the connecting member (4325).

4. The LDI machine self-calibration system based on the bistable bionic compliant mechanism according to claim 3 is characterized in that: The length of the first flexible beam (4322) is greater than the length of the second flexible beam (4324), and the thickness of the first flexible beam (4322) is less than the thickness of the second flexible beam (4324).

5. The LDI machine self-calibration system based on the bistable bionic compliant mechanism according to claim 3 is characterized in that: The fixing member (4321) is symmetrically arranged on both sides of the connecting member (4325), and a plurality of groups of first flexible beams (4322), rigid beams (4323) and second flexible beams (4324) are arranged between the fixing member (4321) and the connecting member (4325).

6. A self-calibration method for LDI machine based on bistable bionic compliant mechanism, characterized in that: include S1, workbench initialization: the motion control platform (200) controls the workbench surface (210) to move to an initial reference position; S2, visual calibration data acquisition: the bistable focusing module (430) quickly switches between a first stable position and a second stable position to adjust the focal position of the visual calibration component (400), thereby acquiring a clear image of the work surface (210); the visual calibration component (400) detects the spatial position of the calibration point on the work surface (210) and records the real-time spatial coordinates of each calibration point; S3, calibration error calculation: the control system calculates the calibration error according to the real-time spatial coordinates of each calibration point collected by the visual calibration component (400) and the ideal spatial coordinates of each calibration point stored in the control system; S4, error compensation: if the calibration error is greater than a set threshold, the control system calculates a compensation parameter according to the calibration error, and adjusts the position of the motion control platform (200) according to the compensation parameter to correct the coordinate deviation of the work surface (210); S5. Repeat calibration verification: the LDI machine self-calibration system repeatedly executes S2, S3, and S4 until the error of each calibration point is less than the set threshold.

7. The LDI machine self-calibration method based on the bistable bionic compliant mechanism according to claim 6 is characterized in that: In step S3, the calculation of the calibration error includes the following steps: Calculate the X-axis direction error: the X-axis direction error is determined by the X-axis grating scale error, the Y-axis and X-axis coupling error, the Z-axis error, and the perpendicularity error between the X-axis and the Y-axis; Calculate the Y-axis direction error: The Y-axis direction error is determined by the Y-axis grating scale error, the Y-axis and Z-axis coupling error, the Z-axis error, and the perpendicularity error between the X-axis and the Y-axis.

8. The LDI machine self-calibration method based on the bistable bionic compliant mechanism according to claim 6 is characterized in that: In step S4, the calculation of compensation parameters includes the following steps: The control system divides the calibration area into a plurality of grids and uses an interpolation algorithm to calculate the error value for each grid point; Based on the grid point error values, the control system obtains optimized compensation parameters by dynamically optimizing an objective function.

9. The LDI machine self-calibration method based on the bistable bionic compliant mechanism according to claim 6, characterized in that: In step S4, the error compensation includes dynamic temperature compensation for avoiding the influence of thermal expansion and dynamic vibration compensation for avoiding the influence of mechanical disturbance.

10. The LDI machine self-calibration method based on the bistable bionic compliant mechanism according to claim 6, characterized in that: The method further comprises S6: after the repeated calibration verification is completed, the control system stores the optimized calibration parameters into a database and generates a calibration report.

Images