Digital twin production line equipment calibration method

Abstract

The invention relates to a digital twin production line equipment calibration method, which comprises the following steps: S1, establishing a digital twin model of a production line, and initializing model parameters; s2, accurately measuring and calibrating the internal structure of the production line equipment; s3, reference equipment is selected, and a site map is initialized; s4, taking the reference equipment as a starting point, performing anchor point signal linking on the equipment to be calibrated one by one, and finally forming an anchor point signal one-way connection network; s5, the twin model is driven to accurately move to the next station by reading servo data of the reference equipment; s6, calculating and calibrating anchor point connection equipment at the current station; s7, traversing the anchor point signal chain, and executing the step S6 on the site equipment of the anchor point equipment until all sites of the anchor point equipment and sub-level anchor point equipment are calibrated; and S8, executing the step S5 until all equipment calibration processes are completed. According to the production line equipment twin model and the calibration method thereof, the calibration efficiency of the production line equipment can be effectively improved, the daily maintenance process can be remarkably simplified, and the maintenance cost is reduced. Meanwhile, the scheme has excellent maintainability, and powerful technical support is provided for long-term stable operation of a production line.

Description

Technical Field

[0001] This technology mainly involves the use of digital twin technology in industrial automation, industrial Internet, and digital factory intelligent manufacturing transformation and upgrading. This technology is mainly suitable for intelligent production line calibration, equipment maintenance scenarios, production line upgrades and transformations, and smart factory construction based on digital twin technology in modern manufacturing. Background Art

[0002] With the introduction and development of the concept of Industry 4.0, digital twin technology has gradually become one of the core supporting technologies for intelligent manufacturing. By creating a virtual factory model to simulate the actual production process, real-time monitoring of the production line status and fault prediction can be achieved, greatly improving production efficiency and service levels. However, in actual applications, how to ensure the consistency between the virtual model and the real environment has become a key challenge.

[0003] At present, there are two main types of common digital twin system initialization methods: one is based on manual measurement, that is, modeling by collecting data such as size and position of production equipment on site; the other is to use machine vision or laser scanners to automatically obtain this information. Although the former is accurate, it is time-consuming and costly, and although the latter is fast and low-cost, it may encounter problems such as occlusion in complex environments, resulting in reduced accuracy. In addition, no matter which method is used, once the initial calibration is completed, it is difficult to effectively respond to the need for readjustment in the event of equipment wear, replacement, etc. The existing digital twin system initialization and subsequent dynamic adjustment mechanism have obvious shortcomings, especially in the face of frequently changing production environments. These problems limit the scope and effect of digital twin technology in production lines.

[0004] Compared with the existing technology, this technology mainly solves the following technical problems: improving the speed and accuracy of equipment calibration in the digital twin system, reducing the number of recalibration times due to equipment changes, thereby reducing maintenance costs and improving the stability and adaptability of the system. Summary of the invention

[0005] The present invention provides a digital twin production line equipment calibration method, which establishes a twin model at the production line level. The present invention solves the above technical problems through the following technical solutions: First, the internal structure of each device on the production line is accurately measured and calibrated to ensure the high consistency between the twin model and the physical device; then the relevant equipment of each logistics site is divided into different calibration groups, a site map is created for the logistics equipment, and each anchor connection device is calibrated in turn; when calibrating the group to be calibrated, the anchor connection device is used as the calibration benchmark, and the logistics equipment in the group is calibrated first, and then the anchor connection device is calibrated based on the logistics equipment, and finally the calibration method is adopted. This method takes the accurately calibrated anchor connection device as the benchmark, gradually expands to the surrounding equipment, and calibrates the remaining equipment. The twin model of production line equipment and its calibration method established by this solution can not only effectively improve the calibration efficiency of production line equipment, but also significantly simplify the daily maintenance process and reduce maintenance costs. At the same time, the solution also has excellent maintainability, providing strong technical support for the long-term stable operation of the production line.

[0006] 2 Working process and principle: S1: In the digital twin system, a digital twin production line consisting of a twin device model is constructed, wherein the twin device model has three-dimensional geometric features and model parameters that are proportional to the real device. The model parameters include device number, anchor point, anchor point signal, and device interface.

[0007] The device number is used to distinguish and identify different twin device models; the anchor point is used to connect to the anchor connection device, and its posture can be accurately expressed and presented through an intuitive and visual XYZ rectangular coordinate system framework; the anchor signal type is a Boolean type, and its main function is to enable the reference device to transmit calibration instructions or signals to the anchor connection device; the device interface is used to associate the anchor point and the anchor signal one by one; the posture transformation matrix of the twin device relative to the global coordinate system can be read from the digital twin system.

[0008] S2: For all real equipment entities, including but not limited to machine tools, special machines, high-bay warehouses, conveyors, robots, trusses and AGVs, the internal structure is accurately measured, and the equipment twin model is accurately calibrated according to the measurement results, mainly to correct the zero point, limit, axis direction and component posture of its kinematic pair.

[0009] S3: Select logistics equipment with global mobility capabilities, such as automated guided vehicles (AGVs), robots, trusses, etc., as benchmark equipment, and initialize the site map of the benchmark equipment in the digital twin environment. The site map records the initial position of the benchmark equipment and the positions of all docking sites; update the position of the benchmark equipment at the current moment to the site map.

[0010] S4: Starting from the reference device, link the anchor signals to the devices to be calibrated one by one. In the current device configuration, for each site, configure a device interface independently, and associate the specific anchor coordinate frame and anchor signal to the device interface. At the same time, in the twin model of the anchor connection device corresponding to each site, also configure a matching device interface, and associate the corresponding anchor and anchor signal to the device interface.

[0011] This process then continues, allocating new interfaces to each site of each anchor connection device, and after allocation, establishing associations with anchors and anchor signals for each of these new interfaces. It is important to ensure that the anchor signal inside the anchor connection device can achieve effective connection and consistency with its corresponding anchor signal outside.

[0012] Then initialize the anchor signal value of all devices to false.

[0013] S5: By reading the servo data generated by the physical device of the reference device, the motion axis of the corresponding digital twin device model is driven to move precisely to the specific site corresponding to the next anchor point connection device.

[0014] S6: Select a suitable anchor point position according to the device connection status, and correct the local posture of the current anchor point coordinate frame of the twin model of the reference device. The correction operation is based on the data obtained from actual measurements. At the same time, make corresponding adjustments to the local posture of the current anchor point coordinate frame of the twin model of the anchor connection device to ensure that the anchor point coordinate frames of the two can accurately coincide in the real physical environment. According to the calculation results, the precise posture of the current anchor point coordinate frame of the reference device in the global coordinate system is determined, and then the anchor point signal value of the reference device is changed to true, thereby triggering the calibration procedure of the anchor connection device. In the calibration procedure, based on the posture information of the current anchor point in the global coordinate system, the expected posture of the origin of the anchor connection device in the global coordinate system is accurately calculated, and the anchor connection device is moved to the calculated precise posture accordingly.

[0015] S7: When the system detects that the anchor connection device has a signal that has not been triggered, the system will automatically read the actual servo data of the device and accurately control it to move to the next station. Then, the system will execute step S6 according to the established process.

[0016] S8: If there are still devices at the level of the current site that have not completed calibration, the system will execute step S5 until all twin devices have successfully completed the calibration process to ensure the comprehensive and accurate operation of the production line.

[0017] Furthermore, in step 2, the calibration can be performed by direct measurement or reference coordinate system method. The direct measurement method refers to the use of high-precision measurement tools such as laser rangefinders, 3D scanners, etc. to measure the actual position, size and posture of the internal components of the device; the reference coordinate system method refers to establishing a global reference coordinate system on the device and calibrating the position and posture of its internal components relative to the coordinate system.

[0018] Furthermore, in step 4, to ensure that the signal connection is not repeated, the anchor signal is designed as a one-way transmission mode, that is, the receiving end anchor signal of each device is unique, and the sending end anchor signal can be one or more. This design is intended to prevent confusion and redundancy in the signal connection process and ensure the accuracy and efficiency of the calibration process. In addition, devices with more sites, such as robots, AGVs, stereoscopic warehouses, etc., are preferred as anchor connection devices for anchor signal association to reduce the cumulative error during calibration.

[0019] Furthermore, in step 5, the anchor point posture formula of the reference device is:

[0020] In the formula, P anchor Represents the coordinate representation of the current anchor point in the twin system. P current =( X , Y , Z ,0,0, θ z ) T represents the global coordinates of the reference device in the twin system, T c w Represents the transformation matrix from the origin coordinate system of the reference device to the global coordinate system of the digital twin system, P offset The local coordinates of the anchor point of the reference device in its origin coordinate system.

[0021] The calculation formula of the origin coordinates of the anchor connection device is:

[0022] In the formula, P cal Represents the coordinate representation of the anchor point connection device in the twin system. P anchor Represents the anchor point coordinate representation of the anchor point connection device; T w cal Represents the transformation matrix from the origin coordinate system of the anchor connection device to the global coordinate system of the digital twin system. Poffset2 Represents the coordinates of the anchor point of the anchor connection device in its origin coordinate system.

[0023] Furthermore, when the position of some devices at the site changes, only the anchor signal chain of the affected device needs to be adjusted. Specifically, the connection between the previous anchor signal chain and the next anchor signal chain of the affected part of the current signal chain needs to be disconnected. Subsequently, based on the device at the affected site that is directly connected to the anchor point, the operations of step 6 and step 7 are performed in sequence until all devices in the site are calibrated.

[0024] Compared with the prior art, the above technical solution mainly solves the following technical problems: 1. Improved the automation level of calibration of digital twin systems.

[0025] 2Simplifies daily maintenance procedures without sacrificing accuracy.

[0026] 3. Enhanced the flexibility and robustness of the system, enabling it to quickly recover to an ideal state even in the event of an emergency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a flow chart of a digital twin production line equipment calibration method proposed by the present invention; Figure 2 A production line layout diagram of a digital twin production line equipment calibration method proposed by the present invention; Figure 3 A distribution diagram of the anchor point coordinate frame predefined by AGV1 of a digital twin production line equipment calibration method proposed in the present invention; Figure 4 A distribution diagram of the anchor point coordinate frame predefined in a stereoscopic warehouse 2 of a digital twin production line equipment calibration method proposed in the present invention; Figure 5 A distribution diagram of the anchor point coordinate frame predefined for the stacker 3 of the digital twin production line equipment calibration method proposed by the present invention; Figure 6 A distribution diagram of the anchor point coordinate frame predefined for the machine tool 4 of the digital twin production line equipment calibration method proposed by the present invention; Figure 7 A distribution diagram of the anchor point coordinate frame predefined for the machine tool 5 of the digital twin production line equipment calibration method proposed in the present invention; Figure 8 A distribution diagram of the anchor point coordinate frame predefined by the truss robot 6 of the digital twin production line equipment calibration method proposed by the present invention; Fig. 9A distribution diagram of the anchor point coordinate frame predefined for a dedicated device 7 of a digital twin production line equipment calibration method proposed in the present invention; Fig.10 A distribution diagram of the anchor point coordinate frame predefined for the conveyor 8 of the digital twin production line equipment calibration method proposed by the present invention; Fig.11 A distribution diagram of the anchor point coordinate frame predefined for the conveyor 9 of the digital twin production line equipment calibration method proposed by the present invention; Fig.12 A distribution diagram of the anchor point coordinate frame predefined for the conveyor 10 of the digital twin production line equipment calibration method proposed by the present invention; Fig.13 A production line site map of the digital twin production line equipment calibration method proposed in the present invention.

[0028] Fig.14 This is a block diagram of the anchor signal chain of the digital twin production line equipment calibration method proposed in the present invention. DETAILED DESCRIPTION

[0029] The following is a detailed description of the embodiments of the present invention in conjunction with the accompanying drawings. This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments.

[0030] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0031] The following will refer to Figure 1-Figure 14 The invention is described in detail with reference to the embodiments.

[0032] like Figure 1 As shown, the present invention provides a digital twin production line equipment calibration method, comprising the following steps: S1: In the digital twin system, a digital twin production line consisting of a twin device model is constructed, wherein the twin device model has three-dimensional geometric features and model parameters that are proportional to the real device. The model parameters include device number, anchor point, anchor point signal, and device interface.

[0033] The anchor point is used to connect to the anchor connection device, and its posture can be accurately expressed and presented through an intuitive and visual XYZ rectangular coordinate system framework; the anchor point signal type is a Boolean type, and its main function is to enable the reference device to transmit calibration instructions or signals to the anchor connection device; the device interface is used to associate the anchor point and the anchor point signal one by one; the posture transformation matrix of the twin device relative to the global coordinate system can be read from the digital twin system.

[0034] like Figure 2 As shown, the production line equipment of an embodiment includes: AGV1, a stereoscopic warehouse 2, a stacker 3, a machine tool 4, a machine tool 5, a truss robot 6, a special machine equipment 7, a conveyor belt 8, a conveyor belt 9, and a conveyor belt 10.

[0035] like Figure 3 As shown, an anchor point coordinate frame 101 is set on the left side of AGV1 to represent its anchor point position; like Figure 4 As shown, an anchor point coordinate frame 201 is set at the lower left corner of the stereoscopic warehouse 2 to represent its anchor point position; like Figure 5 As shown, an anchor point coordinate frame 301 is set at the center of the end of the fork of the stacker 3, and the anchor point coordinate frame 301 is attached to the fork and moves with it, and is used to represent its anchor point posture; like Figure 6 As shown, an anchor point coordinate frame 401 is set at the center of the outer station of the circular station disk of the machine tool 4 to represent its anchor point position; like Figure 7 As shown, an anchor point coordinate frame 501 is set at the center of the outer station of the circular station disk of the machine tool 5 to represent its anchor point position; like Figure 8 As shown, an anchor point coordinate frame 601 is set at the center point of the end effector of the truss robot 6, and the anchor point coordinate frame 601 is attached to the end effector and follows its movement to represent its anchor point position; like Fig. 9 As shown, an anchor point coordinate frame 701 is set on the dedicated machine device 7 to represent its anchor point position; like Fig.10 As shown, two anchor point coordinate frames 801 and 802 are set on the conveyor belt 8, which are used to represent the anchor point positions at its input port and output port respectively; like Fig.11 As shown, two anchor point coordinate frames 901 and 902 are set on the conveyor belt 9, which are used to represent the anchor point positions at its input port and output port respectively; like Fig.12 As shown, an anchor point coordinate frame 1001 is set on the conveyor belt 10 to represent the anchor point position at its input port; S2: For all real equipment entities, including but not limited to machine tools, special machines, high-bay warehouses, conveyors, robots, trusses and AGVs, the internal structure is accurately measured, and the equipment twin model is accurately calibrated according to the measurement results, mainly to correct the zero point, limit, axis direction and component posture of its kinematic pair.

[0036] Calibration can be performed using direct measurement or reference coordinate system methods. Direct measurement refers to the use of high-precision measurement tools such as laser rangefinders and 3D scanners to measure the actual position, size, and posture of the internal components of the device; the reference coordinate system method refers to establishing a global reference coordinate system on the device and calibrating the position and posture of its internal components relative to the coordinate system.

[0037] S3: Select the production line shown in the figure Figure 2 The AGV1 shown is used as a reference device. Fig.13 The site layout diagram of the reference device AGV1 is shown in detail, and the layout diagram accurately records the initial position and posture of the reference device, as well as the position and posture of all preset docking sites. In this site layout diagram, the sites that AGV1 needs to visit in sequence include: site P1, site P2, site P3, site P4 and site P5.

[0038] The operation steps are as follows: First, physically move AGV1 in the physical production line to the starting site P1, and then read the relevant data recorded by the AGV's servo control system to ensure the accuracy of its position and status information. Then, in the digital twin production line, the virtual corresponding AGV1 instance is synchronously updated to ensure that its virtual position also accurately reflects the state of having moved to site P1. This process realizes seamless connection and real-time synchronization of AGV1 position information between the physical production line and the digital twin production line.

[0039] S4: Reference Fig.13 The site layout diagram shown clearly presents five sites, and accordingly, five device interfaces are configured in the automatic guided vehicle AGV1, and five anchor signals are introduced, which are named anchor signal 1 to anchor signal 5, respectively. These signals correspond one by one to sites P1 to P5 in the site layout diagram.

[0040] In the system configuration of AGV1, we made the following precise association settings: the anchor coordinate frame identified as 101 was associated with anchor signal 1 and assigned to device interface 1; similarly, the anchor coordinate frame 101 was also associated with anchor signals 2 to 5, and assigned to device interfaces 2 to 5 in turn. This series of operations ensures that each site has a corresponding device interface and anchor signal, thereby achieving accurate navigation and position confirmation of AGV1 between sites.

[0041] An interface and an anchor signal 6 are created in the stereoscopic warehouse 2, the anchor coordinate frame is identified as 201 and associated with the anchor signal 6, and is assigned to the device interface.

[0042] An interface and an anchor signal 7 are created in the stacker 3, and the anchor coordinate frame is identified as 301 and associated with the anchor signal 7, and is assigned to the device interface.

[0043] An interface and an anchor signal 8 are created in the machine tool 4, the anchor coordinate frame is identified as 401 and associated with the anchor signal 8, and is assigned to the device interface.

[0044] An interface and an anchor signal 9 are created in the truss robot 6, and the anchor coordinate frame is identified as 601 and associated with the anchor signal 9, and is assigned to the device interface.

[0045] An interface and an anchor signal 10 are created in the machine tool 5, and the anchor coordinate frame is identified as 501 and associated with the anchor signal 10, and is assigned to the device interface.

[0046] An interface and an anchor signal 11 are created in the dedicated device 7, the anchor coordinate frame is identified as 701 and associated with the anchor signal 11, and is assigned to the device interface.

[0047] Two independent interfaces and two key anchor signals, namely anchor signal 12 and anchor signal 13, are created in the conveyor 8. Specifically, the anchor coordinate frame is first identified as 801 and associated with anchor signal 12, and this combination is assigned to device interface 1 to ensure the coordination and accuracy of its functions. Similarly, another anchor coordinate frame is identified as 802 and associated with anchor signal 13, and this combination is assigned to device interface 2.

[0048] Two independent interfaces and two key anchor signals, namely anchor signal 14 and anchor signal 15, are created in the conveyor 9. Specifically, the anchor coordinate frame is first identified as 901 and associated with anchor signal 14, and this combination is assigned to device interface 1 to ensure the coordination and accuracy of its functions. Similarly, another anchor coordinate frame is identified as 902 and associated with anchor signal 15, and this combination is assigned to device interface 2.

[0049] An interface and an anchor signal 16 are created in the conveyor 10, and the anchor coordinate frame is identified as 1001 and associated with the anchor signal 16, and assigned to the device interface.

[0050] Reference Fig.14 The digital twin production line anchor signal connection block diagram shown in the figure, in the digital twin system, taking the reference device AGV1 as the starting point, the following anchor signal unidirectional connection network is constructed: Anchor signal 1 is linked to anchor signal 6 and anchor signal 7 at the same time, realizing parallel transmission of information; then, anchor signal 2 is also linked to anchor signal 8 and anchor signal 9 at the same time; in addition, anchor signal 3 is directionally connected to anchor signal 10, anchor signal 4 is directionally linked to anchor signal 11; similarly, anchor signal 5 is directionally connected to anchor signal 12. In particular, anchor signal 13 is directionally linked to anchor signal 14, and anchor signal 15 is directionally linked to anchor signal 16. All signal chains are unidirectional signal transmission to ensure that the calibration of all anchor-connected devices can be completed sequentially; then the anchor signal values ​​of all devices are initialized to false.

[0051] S5: By reading the servo data generated by the physical device of the reference device, the motion axis of the corresponding digital twin device model is driven to move accurately to the next station.

[0052] S6: Select a suitable anchor point position according to the device connection status, and correct the local posture of the current anchor point coordinate frame of the twin model of the reference device. The correction operation is based on the data obtained from actual measurements. At the same time, make corresponding adjustments to the local posture of the current anchor point coordinate frame of the twin model of the anchor connection device to ensure that the anchor point coordinate frames of the two can accurately coincide in the real physical environment. According to the calculation results, the precise posture of the current anchor point coordinate frame of the reference device in the global coordinate system is determined, and then the anchor point signal value of the reference device is changed to true, thereby triggering the calibration procedure of the anchor connection device. In the calibration procedure, according to the posture information of the current anchor point in the global coordinate system, the expected posture of the origin of the anchor connection device in the global coordinate system is accurately calculated, and the anchor connection device is moved to the calculated precise posture accordingly.

[0053] The anchor point posture formula of the reference device is: In the formula, P anchor Represents the coordinate representation of the current anchor point in the twin system. P current =( X , Y , Z ,0,0, θ z ) T represents the global coordinates of the reference device in the twin system, T c w Represents the transformation matrix from the origin coordinate system of the reference device to the global coordinate system of the digital twin system, P offset The local coordinates of the anchor point of the reference device in its origin coordinate system.

[0054] The calculation formula of the origin coordinates of the anchor connection device is:

[0055] In the formula, P cal Represents the coordinate representation of the anchor point connection device in the twin system. P anchor Represents the anchor point coordinate representation of the anchor point connection device; T w cal Represents the transformation matrix from the origin coordinate system of the anchor connection device to the global coordinate system of the digital twin system. P offset2 Represents the coordinates of the anchor point of the anchor connection device in its origin coordinate system.

[0056] Reference Fig.13 The site map of AGV1 is shown. When AGV1 arrives at site P1, it will perform the calibration process for the stereoscopic warehouse 2 and the stacker 3. In this process, according to the anchor point posture calculation formula (1) of the reference equipment, the pose coordinates of the anchor point coordinate frame M1 of AGV1 in the global coordinate system are accurately calculated.

[0057] Specifically, first, the anchor coordinate frame 201 of the anchor stereoscopic warehouse 2 is moved to the position M1, and the coordinate value of the anchor coordinate frame 201 in the local coordinate system of the stereoscopic warehouse 2 is obtained by precise measurement. Then, the physical device of the stacker 3 is controlled to move to the specified position shown in the figure, and the anchor coordinate frame 301 of the anchor stacker 3 is also moved to M1 by measuring the relative position of the center point of the end of the fork of the stacker 3 relative to M1, and the coordinate value of the anchor coordinate frame 301 in the local coordinate system of the stacker 3 is obtained.

[0058] Next, the anchor signal 1 of AGV1 is set to the true state, and the calibration procedures of the three-dimensional warehouse 2 and the stacker 3 are triggered at the same time. Using the calculation formula (2) of the origin coordinates of the anchor connection device, the pose coordinates of the twin model origins of the three-dimensional warehouse 2 and the stacker 3 in the global coordinate system can be calculated. According to the calculation results, the twin model origins of the three-dimensional warehouse 2 and the stacker 3 are moved to the calculated positions to complete the calibration process.

[0059] Similarly, when AGV1 moves to site P2, calibration of machine tool 4 and truss robot 6 will be performed; when AGV1 moves to site P3, calibration of machine tool 5 will be performed; when AGV1 moves to site P4, calibration of special equipment 7 will be performed; and when AGV1 moves to site P5, calibration of conveyor 8 will be performed.

[0060] In particular, after the conveyor 8 is calibrated, it is used as a new reference device. Through precise measurement, the anchor coordinate frame 901 of the conveyor 9 is moved to the anchor coordinate frame 802 of the conveyor 8. Then, the anchor posture calculation formula (1) is used again to calculate the pose coordinates of the anchor coordinate frame 802 of the conveyor 8 in the global coordinate system. Next, the pose coordinates of the origin of the twin model of the conveyor 9 in the global coordinate system are calculated using the calculation formula (2) for the origin coordinates of the anchor connection device. Finally, according to the calculation results, the origin of the twin model of the conveyor 9 is moved to the calculated position, thereby completing the calibration process of the conveyor 9.

[0061] S7: When the system detects that the anchor connection device has a signal that has not been triggered, the system will automatically read the actual servo data of the device and accurately control it to move to the next station. Then, the system will execute step S6 according to the established process.

[0062] S8: If there are still devices at the level of the current site that have not completed calibration, the system will execute step 5 until all twin devices have successfully completed the calibration process to ensure the comprehensive and accurate operation of the production line.

Claims

1. A digital twin production line equipment calibration method, characterized in that: The following steps are involved: S1: In the digital twin system, a digital twin production line consisting of a twin device model is constructed, wherein the twin device model has three-dimensional geometric features and model parameters that are proportional to the real device. The model parameters include device number, anchor point, anchor point signal, and device interface.

2. The device number is used to distinguish and identify different twin device models; the anchor point is used to connect to the anchor connection device, and its posture can be accurately expressed and presented through an intuitive and visual XYZ rectangular coordinate system framework; the anchor signal type is a Boolean type, and its main function is to realize the reference device to transmit calibration instructions or signals to the anchor connection device; the device interface is used to associate the anchor point and the anchor signal one by one; the posture transformation matrix of the twin device relative to the global coordinate system can be read from the digital twin system. 3.S2: For all real equipment entities, including but not limited to machine tools, special machines, warehouses, conveyors, robots, trusses and AGVs, the internal structure is accurately measured, and the equipment twin model is accurately calibrated according to the measurement results, mainly to correct the zero point, limit, axis direction and component posture of its kinematic pair. 4.S3: Select logistics equipment with global mobility capabilities, such as automated guided vehicles (AGVs), robots, trusses, etc., as benchmark equipment, and initialize the site map of the benchmark equipment in the digital twin environment. The site map records the initial position of the benchmark equipment and the positions of all docking sites; update the position of the benchmark equipment at the current moment to the site map. 5.S4: Starting from the reference device, anchor point signals are linked to the devices to be calibrated one by one. In the current device configuration, a device interface is independently configured for each site, and a specific anchor point coordinate frame and anchor point signal are associated with the device interface. At the same time, in the twin model of the anchor point connection device corresponding to each site, a matching device interface is also configured, and the corresponding anchor point and anchor point signal are associated with the device interface.

6. Then, the process continues, assigning new interfaces to each site of each anchor connection device, and after the assignment, establishing associations with anchors and anchor signals for these new interfaces. It is important to ensure that the anchor signal inside the anchor connection device can achieve effective connection and consistency with the corresponding anchor signal outside it.

7. Then initialize the anchor signal value of all devices to false. 8.S5: By reading the servo data generated by the physical device of the reference device, the motion axis of the corresponding digital twin device model is driven to move precisely to the specific site corresponding to the next anchor point connection device. 9.S6: Select a suitable anchor point position according to the device connection status, and correct the local posture of the current anchor point coordinate frame of the twin model of the reference device. The correction operation is based on the data obtained from actual measurements. At the same time, make corresponding adjustments to the local posture of the current anchor point coordinate frame of the twin model of the anchor connection device to ensure that the anchor point coordinate frames of the two can accurately coincide in the real physical environment. According to the calculation results, determine the precise posture of the current anchor point coordinate frame of the reference device in the global coordinate system, and then change the anchor point signal value of the reference device to true, thereby triggering the calibration procedure of the anchor connection device. In the calibration procedure, based on the posture information of the current anchor point in the global coordinate system, the expected posture of the origin of the anchor connection device in the global coordinate system is accurately calculated, and the anchor connection device is moved to the calculated precise posture accordingly.

10. S7: When the system detects that the anchor connection device has a signal that has not been triggered, it will automatically read the actual servo data of the device and accurately control it to move to the next station. Then, the system will execute step S6 according to the established process.

11. S8: If there are still devices at the level of the current site that have not completed calibration, the system will execute step S5 until all twin devices have successfully completed the calibration process to ensure the comprehensive and accurate operation of the production line.

12. A digital twin production line equipment calibration method according to claim 1, characterized in that: In step 1, the anchor point posture of the anchor connection device after calibration coincides with the anchor point posture of the reference device.

13. A digital twin production line equipment calibration method according to claim 1, characterized in that: In step 2, the calibration method can be direct measurement method and reference coordinate system method. Direct measurement method refers to the use of high-precision measurement tools such as laser rangefinders, 3D scanners, etc. to measure the actual position, size and posture of the internal components of the equipment; the reference coordinate system method refers to establishing a global reference coordinate system on the equipment and calibrating the position and posture of its internal components relative to the coordinate system.

14. A digital twin production line equipment calibration method according to claim 1, characterized in that: In step 3, the calibration axis of the reference equipment can be parked at various sites, and its position at each site can be used to calibrate the anchor connection equipment at the site. In addition, for equipment in relatively fixed positions, such as conveyors, machine tools, and special mechanical equipment, they can be classified as logistics equipment and their site posture is defined as the current posture of the equipment.

15. A digital twin production line equipment calibration method according to claim 1, characterized in that: In step 4, to ensure that the signal connection is not repeated, the anchor signal is designed as a one-way transmission mode, that is, the receiving end anchor signal of each device is unique, and the sending end anchor signal can be one or more. This design is intended to prevent confusion and redundancy in the signal connection process and ensure the accuracy and efficiency of the calibration process. In addition, devices with more sites, such as robots, AGVs, and stereoscopic warehouses, are preferred as anchor connection devices for anchor signal association to reduce the cumulative error during calibration.

16. A digital twin production line equipment calibration method according to claim 1, characterized in that: In step 6, the anchor point posture formula of the reference device is:

17. In the formula, P anchor Represents the coordinate representation of the current anchor point in the twin system. P current =( X , Y , Z ,0,0, θ z ) T represents the global coordinates of the reference device in the twin system, T c w Represents the transformation matrix from the origin coordinate system of the reference device to the global coordinate system of the digital twin system, P offset is the local coordinate of the anchor point of the reference device in its origin coordinate system. The calculation formula of the origin coordinate of the anchor point connection device is:

18. In the formula, P cal Represents the coordinate representation of the anchor point connection device in the twin system. P anchor Represents the anchor point coordinate representation of the anchor point connection device; T w cal Represents the transformation matrix from the origin coordinate system of the anchor connection device to the global coordinate system of the digital twin system. P offset2 Represents the coordinates of the anchor point of the anchor connection device in its origin coordinate system.

19. A digital twin production line equipment calibration method according to claim 1, characterized in that: When the position of some equipment at a site changes, only the anchor signal chain of the affected equipment needs to be adjusted. Specifically, the connection between the previous anchor signal chain and the next anchor signal chain of the affected part of the current signal chain needs to be disconnected. Then, based on the equipment at the affected site that is directly connected to the anchor point, the operations of steps 6 and 7 are performed in sequence until all equipment in the site is calibrated.

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