A Closed-Loop Control Method, Storage Medium and System for a Multi-Axis Sample Stage

Abstract

The present invention relates to a closed-loop control method, storage medium and system for a multi-axis sample stage. The method includes the following steps: receiving an instruction issued by a host computer, parsing the instruction, performing motion planning according to the instruction parsing result, and determining the motion parameters of each axis motor; receiving and processing the motor motion parameters and the real-time position of the single-axis motor uploaded by all single-axis drive modules, and uploading the processing result to the host computer; performing motion correction through position sensor system error calibration and guide rail error calibration. The present invention uses a capacitance grating sensor as the position sensor. Compared with a multi-axis sample stage with open-loop control, it can improve the reliability and control accuracy of the system, and the increase in the cost of the system is also limited, which is beneficial to large-scale application. Through the position feedback during the movement of each axis of the sample stage, the position error caused by the straightness and parallelism of the guide rail is compensated, so that the sample can achieve higher position accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of automatic control, and particularly relates to a multi-axis sample stage closed-loop control method, a storage medium, and a system. Background Art

[0002] The multi-axis sample stage is a necessary component of many high-end imaging devices such as scanning electron microscopes, and can realize the translational or rotational observation of samples. The multi-axis sample stage can not only realize the independent movement of a single axis, but also realize the multi-axis linkage to meet different imaging scanning requirements. The structure of the closed-loop controlled multi-axis sample stage includes a guide rail, a motor, a limit switch, a position sensor, a motor drive module, a multi-axis motion control module, a host computer, etc.

[0003] With the increasing scanning speed and imaging accuracy of imaging devices, the requirements for the real-time performance and accuracy of motion control are getting higher and higher. In order to achieve a higher position measurement accuracy in the existing closed-loop controlled multi-axis sample stage control system, a linear grating encoder is mostly used as the feedback quantity. The advantage is that the control accuracy is relatively high, but the disadvantage is that the price of the linear grating encoder is relatively high, resulting in a relatively high overall cost of the system. At the same time, the position accuracy of the sample stage is directly related to the accuracy of the motion axis guide rail, and the price of the high-precision guide rail is relatively high. Summary of the Invention

[0004] In order to achieve the above objects and other advantages of the present invention, the first object of the present invention is to provide a multi-axis sample stage closed-loop control method, including the following steps:

[0005] Receive the instruction issued by the host computer, parse the instruction, perform motion planning according to the instruction parsing result, determine the motion parameters of each axis motor, and send the motion parameters to the corresponding single-axis drive module;

[0006] Receive and process the motor motion parameters and the real-time position of the single-axis motor uploaded by all single-axis drive modules, and upload the processing result to the host computer;

[0007] In the case of observing a standard sample with an electron microscope, control the single-axis movement of the motor by a preset distance, read the movement distance displayed by the position sensor, perform this operation several times, read the movement distance each time, calculate the average error of the position sensor, and correct the position sensor through the average error;

[0008] Divide the length of the single-axis guide rail into several parts, control the motor to move the single axis from the initial position to the maximum position, measure the actual length of each section of the single-axis guide rail through the corrected position sensor, and calculate the length error of the single-axis guide rail within each length range;

[0009] Obtain the distance that the single-axis motor needs to move, combine with the length error of the single-axis guide rail, calculate the actual distance that the single-axis motor needs to move, and send it to the single-axis drive module.

[0010] Further, the steps of receiving the instruction sent by the host computer, parsing the instruction, and performing motion planning according to the instruction parsing result to determine the motion parameters of each axis motor include the following:

[0011] Receive the instruction sent by the host computer, and the format of the instruction is "priority + instruction name + instruction parameter";

[0012] Store the instructions in different instruction buffer queues according to different priorities of the instructions;

[0013] Take out the instruction with the highest priority, parse the instruction content according to the instruction name, combine with the instruction parameter, and calculate the single-axis motor that needs to move and its moving direction, speed and distance;

[0014] Send the motion parameters to the corresponding single-axis drive module.

[0015] Further, the steps of receiving and processing the motor motion parameters and the real-time position of the single-axis motor uploaded by all single-axis drive modules and uploading the processing result to the host computer include the following:

[0016] Receive the single-axis parameter information uploaded by the single-axis drive module;

[0017] Parse the single-axis parameter information and convert it into a unified upload parameter format of "motion axis name + parameter name + parameter value";

[0018] Upload the single-axis parameter information with the converted upload parameter format to the host computer and display it.

[0019] Further, the standard sample includes several square blocks, and the preset distance is the side length of a square block.

[0020] Further, the step of dividing the length of the single-axis guide rail into several parts specifically means dividing the length of the single-axis guide rail into several equal parts.

[0021] The second object of the present invention is to provide a computer-readable storage medium, on which program instructions are stored, and when the program instructions are executed, a multi-axis sample stage closed-loop control method is implemented.

[0022] The third object of the present invention is to provide a closed-loop control system for a multi-axis sample stage, including a single-axis drive module, a motion control module, and a host computer; the single-axis drive module communicates bidirectionally with the motion control module, and the motion control module communicates bidirectionally with the host computer; the motors corresponding to each axis of the multi-axis sample stage are controlled by separate single-axis drive modules, and the limit switches and position sensors of each axis are connected to the corresponding single-axis drive modules;

[0023] The single-axis drive module is configured to receive the single-axis motion instruction from the motion control module, control the motion of the motor of the corresponding axis of the multi-axis sample stage according to the single-axis motion instruction, and upload the real-time position of the single axis and the motion state parameters of the motor to the motion control module;

[0024] The motion control module is configured to receive the multi-axis motion instruction from the host computer, determine the motion speed, motion direction, and motion steps of each axis according to the pre-calibrated motion parameters of each axis, and issue instructions to the single-axis drive module, receive the real-time position of the single axis and the motion state parameters of the motor uploaded by the single-axis drive module, and upload the analysis result to the host computer;

[0025] The host computer is configured to receive the sample stage motion control instruction input by the user, analyze the selected motion mode by the user, convert it into a multi-axis motion instruction, issue it to the motion control module, and at the same time receive the motion parameters and positions of each axis of the sample stage uploaded by the motion control module and display them.

[0026] Further, the single-axis drive module includes a first microcontroller, a motor drive module, a limit switch detection module, a position sensor detection module, and a first power supply module;

[0027] The first microcontroller is configured to analyze the communication instruction sent by the motion control module, control the speed, direction, and steps of the motor through the motor drive module, and receive the data from the limit switch detection module and the position sensor detection module;

[0028] The limit switch detection module is configured to determine the limit position of each motion axis;

[0029] The position sensor detection module is configured to detect the motion position of each axis in real time and feedback it to the first microcontroller;

[0030] The first power supply module is configured to supply power to the first microcontroller, the motor drive module, the limit switch detection module, and the position sensor detection module.

[0031] Further, the motion control module includes a second microcontroller, a first communication module, a second communication module, and a second power supply module;

[0032] The second microcontroller includes an instruction parsing module, a motion planning module, and a status detection module; the instruction parsing module is used to parse the multi-axis motion instructions of the host computer received through the first communication module; the motion planning module is used to determine the motion speed, motion direction, and motion steps of each axis according to the pre-calibrated motion parameters of each axis, and send instructions to the single-axis drive module through the second communication module; the status detection module is used to analyze the single-axis real-time position and the motion state parameters of the motor uploaded by the single-axis drive module received through the second communication module, and upload the analysis results to the host computer through the first communication module;

[0033] The second power supply module is used to supply power to the second microcontroller, the first communication module, and the second communication module.

[0034] Further, the host computer includes a main control module, a user interaction module, and a third communication module;

[0035] The user interaction module is used to receive the sample stage motion control instructions input by the user;

[0036] The main control module is used to analyze the selected motion mode of the user, convert it into multi-axis motion instructions, send them to the motion control module through the third communication module, and at the same time receive the motion parameters and positions of each axis of the sample stage uploaded by the motion control module, and display them on the user interaction module.

[0037] Compared with the prior art, the beneficial effects of the present invention are:

[0038] The present invention provides a multi-axis sample stage closed-loop control system, which uses a capacitive grating sensor as a position sensor. Compared with the multi-axis sample stage with open-loop control, it can improve the reliability and control accuracy of the system, and the increase in the cost of the system is also limited, which is beneficial to large-scale application.

[0039] The present invention compensates for the position error caused by the straightness and parallelism of the guide rail through the position feedback during the motion of each axis of the sample stage, so that the sample achieves higher position accuracy.

[0040] The above description is only an overview of the technical solution of the present invention. In order to be able to understand the technical means of the present invention more clearly and implement it according to the content of the specification, the following takes the preferred embodiments of the present invention and combines the accompanying drawings to describe in detail as follows. The specific implementation manners of the present invention are given in detail by the following embodiments and their accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings described herein are used to provide a further understanding of the present invention, and constitute a part of this application. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0042] Figure 1 Schematic diagram of a closed-loop control system for a multi-axis sample stage in Embodiment 1;

[0043] Figure 2 Flowchart of a closed-loop control method for a multi-axis sample stage in Embodiment 2;

[0044] Figure 3 Schematic diagram of a standard sample;

[0045] Figure 4 Schematic diagram of an electronic device in Embodiment 3;

[0046] Figure 5 Schematic diagram of a computer-readable storage medium in Embodiment 4. Detailed implementation manners

[0047] Next, in combination with the accompanying drawings and specific implementation manners, the present invention will be further described. It should be noted that, on the premise of no conflict, any combination can be formed among the following-described embodiments or technical features to form a new embodiment.

[0048] Embodiment 1

[0049] A closed-loop control system for a multi-axis sample stage, as Figure 1 shown, includes a single-axis drive module, a motion control module, and a host computer; the single-axis drive module communicates bidirectionally with the motion control module, and the motion control module communicates bidirectionally with the host computer; the motor corresponding to each axis of the multi-axis sample stage is controlled by a separate single-axis drive module, and the limit switch and position sensor of each axis are also connected to the corresponding single-axis drive module. In this embodiment, a capacitance grating sensor is used as the position sensor.

[0050] The single-axis drive module is configured to receive the single-axis motion instruction from the motion control module, control the motion of the motor of the corresponding axis of the multi-axis sample stage according to the single-axis motion instruction, and upload the real-time position of the single axis and the motion state parameters of the motor to the motion control module;

[0051] The motion control module is configured to receive the multi-axis motion instruction from the host computer, determine the motion speed, motion direction, and motion steps of each axis according to the pre-calibrated motion parameters of each axis, and send an instruction to the single-axis drive module, receive the real-time position of the single axis and the motion state parameters of the motor uploaded by the single-axis drive module, and upload the analysis result to the host computer;

[0052] The host computer is configured to receive the sample stage motion control instruction input by the user, analyze the selected motion mode by the user, convert it into a multi-axis motion instruction, send it to the motion control module, and at the same time receive the motion parameters and positions of each axis of the sample stage uploaded by the motion control module and display them.

[0053] The single-axis drive module includes a first microcontroller, a motor drive module, a limit switch detection module, a position sensor detection module, and a first power supply module;

[0054] The first microcontroller is used to parse the communication instructions sent by the motion control module, control the speed, direction, and number of steps of the motor through the motor drive module, and receive data from the limit switch detection module and the capacitive grating sensor detection module;

[0055] The limit switch detection module is used to determine the limit positions of each motion axis to prevent each axis from moving beyond the designed range;

[0056] The position sensor detection module is used to detect the motion position of each axis in real time and feed it back to the first microcontroller;

[0057] The first power supply module is used to supply power to the first microcontroller, the motor drive module, the limit switch detection module, and the position sensor detection module.

[0058] The motion control module includes a second microcontroller, a first communication module ( Figure 1 the UDP communication module in Figure 1 ), a second communication module (

[0059] the serial communication module in

[0060] ), and a second power supply module;

[0061] The second microcontroller includes an instruction parsing module, a motion planning module, and a status detection module; The instruction parsing module is used to parse the multi-axis motion instructions of the host computer received through the first communication module; The motion planning module is used to determine the motion speed, motion direction, and number of motion steps of each axis according to the pre-calibrated motion parameters of each axis, and send instructions to the single-axis drive module through the second communication module; In this embodiment, the second communication module is a serial communication module, and the instructions it sends are serial instructions. The status detection module is used to analyze the single-axis real-time position and the motion state parameters of the motor uploaded by the single-axis drive module received through the second communication module, and upload the analysis results to the host computer through the first communication module; The second power supply module is used to supply power to the second microcontroller, the first communication module, and the second communication module.

[0061] The host computer includes a main control module, a user interaction module ( Figure 1 the user interface of the host computer part in Figure 1 ), and a third communication module (

[0062] the communication module of the host computer part in

[0063] ); The user interaction module is used to receive the sample stage motion control instructions input by the user; For example, the user can select the motion mode of the sample stage on the user interface according to the following steps:

[0063] Select which axis or axes need to move;

[0064] Select the movement direction of the axis to be moved;

[0065] The movement mode of the axis to be moved, such as: moving to an absolute coordinate point; moving a relative distance; moving at a constant speed, and the movement speed and direction can be adjusted at any time, etc.

[0066] The main control module is used to analyze the movement mode selected by the user, convert it into a multi-axis movement instruction, send it to the movement control module through the third communication module, and at the same time receive the movement parameters and positions of each axis of the sample stage uploaded by the movement control module and display them on the user interaction module.

[0067] Embodiment 2

[0068] Take the movement control module as the server and the host computer as the client. Implement the control method of the multi-axis sample stage closed-loop control system in the above embodiment, such as Figure 2 As shown, it includes the following steps:

[0069] Receive the instruction sent by the host computer, parse the instruction, perform motion planning according to the instruction parsing result, determine the motion parameters of each axis motor, including motion direction, motion speed, motion acceleration, motion steps, etc., and send the motion parameters to the corresponding single-axis drive module; specifically, it includes the following steps:

[0070] Receive the instruction sent by the host computer, and the format of the instruction is "priority + instruction name + instruction parameter";

[0071] Store the instructions in different instruction buffer queues according to different priorities of the instructions;

[0072] Take out the instruction with the highest priority, parse the instruction content according to the instruction name, combine the instruction parameters, and calculate the single-axis motor to be moved and its motion direction, speed and distance;

[0073] Send the motion parameters to the corresponding single-axis drive module through serial communication.

[0074] Receive and process the motor motion parameters and the real-time position of the single-axis motor uploaded by all single-axis drive modules, upload the processing result to the host computer, and display it on the user interface; specifically, it includes the following steps:

[0075] Receive the single-axis parameter information uploaded by the single-axis drive module;

[0076] Parse the single-axis parameter information and convert it into a unified upload parameter format of "axis name to be moved + parameter name + parameter value";

[0077] Upload the single-axis parameter information with the converted upload parameter format to the host computer and display it.

[0078] The image resolution of a scanning electron microscope can reach 1 nm or even higher, while the systematic error of a capacitive grating sensor itself is about 1 μm. Therefore, the systematic error of the capacitive grating sensor itself can be calibrated using electron microscope images. Specifically, it includes the following steps:

[0079] When observing a standard sample using an electron microscope, as Figure 3 shown, the standard sample includes several square blocks. The side length of a square block is about 147 μm. Control the motor to move a preset distance in a single axis. In this embodiment, the preset distance is the side length of a square block, that is, control the motor to move a certain axis by 147 μm, which means moving the standard sample one grid in one direction; read the moving distance N1 displayed by the position sensor, and continue the above operation (m - 1) times, read the moving distances N2, N3,..., Nm each time, and calculate the average error of the position sensor err = (N1 + N2 + N3 +... + Nm) / (m * 147 μm), and correct the position sensor through the average error.

[0080] Divide the length of the single-axis guide rail into several parts. In this embodiment, divide the length of the single-axis guide rail into several equal parts. Let the length of the single-axis guide rail be L, divided into n equal parts, denoted as L1, L2,..., Ln. Control the motor to move the single axis from the initial position to the maximum position, measure the actual length M1 of the L1 section of the single-axis guide rail, the actual length M2 of the L2 section,......, the actual length Mn of the Ln section through the corrected position sensor, and calculate e1 = M1 / (L / n), e2 = M2 / (L / n),......, en = Mn / (L / n) respectively, then the length error of the guide rail within each length range can be calculated.

[0081] When the system controls each axis to move, it needs to move to a certain specified position, and calculate the actual required number of movement steps and direction according to the calibrated data. Specifically, it includes: obtaining the distance Ln that the single-axis motor needs to move, considering the guide rail error, and combining the length error of the single-axis guide rail, calculating the actual distance Ln / en that the single-axis motor needs to move and sending it to the single-axis drive module.

[0082] Embodiment 3

[0083] An electronic device 200, as Figure 4 shown, includes but is not limited to: a memory 201, on which program code is stored; a processor 202, which is connected to the memory, and when the program code is executed by the processor, a multi-axis sample stage closed-loop control method is implemented. For a detailed description of the method, reference can be made to the corresponding description in the above method embodiments, and details will not be repeated here.

[0084] Embodiment 4

[0085] A computer-readable storage medium, as Figure 5As shown, program instructions are stored thereon, and a closed-loop control method for a multi-axis sample stage is implemented when the program instructions are executed. For a detailed description of the method, reference can be made to the corresponding description in the above method embodiments, which will not be elaborated here.

[0086] Embodiment 5

[0087] A computer program product includes computer programs / instructions, and a closed-loop control method for a multi-axis sample stage is implemented when the computer programs / instructions are executed by a processor. For a detailed description of the method, reference can be made to the corresponding description in the above method embodiments, which will not be elaborated here.

[0088] It should also be noted that the term "including", "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, commodity or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, commodity or device including the element.

[0089] Each embodiment in this specification is described in a progressive manner. The same or similar parts among the embodiments can be referred to each other, and the key point of each embodiment is to illustrate the differences from other embodiments.

[0090] The above is only for the embodiments of this specification and is not used to limit one or more embodiments of this specification. For those skilled in the art, one or more embodiments of this specification can have various changes and transformations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of one or more embodiments of this specification shall be included within the scope of the claims of one or more embodiments of this specification. One or more embodiments of this specification, one or more embodiments of this specification, one or more embodiments of this specification, one or more embodiments of this specification.

Claims

1. A closed-loop control method for a multi-axis sample stage, characterized in that, It includes the following steps: Receive the instructions sent by the host computer, parse the instructions, perform motion planning according to the instruction parsing results, determine the motion parameters of each axis motor, and send the motion parameters to the corresponding single-axis drive module; Receive and process the motor motion parameters and the real-time positions of the single-axis motors uploaded by all single-axis drive modules, and upload the processing results to the host computer; When observing a standard sample with an electron microscope, control the single-axis motion of the motor by a preset distance, read the motion distance displayed by the position sensor, perform this operation several times, read the motion distance each time, calculate the average error of the position sensor, and correct the position sensor through the average error; Divide the length of the single-axis guide rail into several parts, control the motor to move the single axis from the initial position to the maximum position, measure the actual length of each section of the single-axis guide rail with the corrected position sensor, and calculate the length error of the single-axis guide rail within each length range; Obtain the distance that the single-axis motor needs to move, combine it with the length error of the single-axis guide rail, calculate the actual distance that the single-axis motor needs to move, and send it to the single-axis drive module.

2. The closed-loop control method for a multi-axis sample stage according to claim 1, wherein The steps of receiving the instructions sent by the host computer, parsing the instructions, performing motion planning according to the instruction parsing results, and determining the motion parameters of each axis motor include the following steps: Receive the instructions sent by the host computer, and the format of the instructions is "priority + instruction name + instruction parameters"; Store the instructions in different instruction buffer queues according to different priorities of the instructions; Take out the instruction with the highest priority, parse the instruction content according to the instruction name, combine it with the instruction parameters, and calculate the single-axis motor that needs to move and its moving direction, speed and distance; Send the motion parameters to the corresponding single-axis drive module.

3. A closed-loop control method for a multi-axis sample stage according to claim 1, characterized in that, The steps of receiving and processing the motor motion parameters and the real-time positions of the single-axis motors uploaded by all single-axis drive modules, and uploading the processing results to the host computer include the following steps: Receive the single-axis parameter information uploaded by the single-axis drive module; Parse the single-axis parameter information and convert it into a unified upload parameter format of "motion axis name + parameter name + parameter value"; Upload the single-axis parameter information with the converted upload parameter format to the host computer and display it.

4. A closed-loop control method for a multi-axis sample stage according to claim 1, characterized in that, The standard sample includes several square blocks, and the preset distance is the side length of a square block.

5. A closed-loop control method for a multi-axis sample stage according to claim 1, characterized in that, The specific operation of dividing the length of the single-axis guide rail into several parts is to divide the length of the single-axis guide rail into several equal parts.

6. A computer-readable storage medium, characterized in that, It stores program instructions, and when the program instructions are executed, the method described in any one of claims 1 to 5 is implemented.

7. A multi-axis sample stage closed-loop control system implemented by using the method described in any one of claims 1 to 5, characterized in that: It includes a single-axis drive module, a motion control module, and a host computer; the single-axis drive module communicates with the motion control module bidirectionally, and the motion control module communicates with the host computer bidirectionally; the motors corresponding to each axis of the multi-axis sample stage are controlled by separate single-axis drive modules, and the limit switches and position sensors of each axis are connected to the corresponding single-axis drive module; The single-axis drive module is used to receive the single-axis motion instructions of the motion control module, control the motion of the motor of the corresponding axis of the multi-axis sample stage according to the single-axis motion instructions, and upload the real-time position of the single axis and the motion state parameters of the motor to the motion control module; The motion control module is used to receive multi-axis motion instructions from the host computer, determine the motion speed, motion direction, and motion steps of each axis according to the pre-calibrated motion parameters of each axis, and send instructions to the single-axis drive module. It also receives the single-axis real-time position and the motion state parameters of the motor uploaded by the single-axis drive module, and uploads the analysis results to the host computer; The host computer is used to receive the sample stage motion control instructions input by the user, analyze the selected motion mode, convert it into multi-axis motion instructions, and send them to the motion control module. At the same time, it receives the motion parameters and positions of each axis of the sample stage uploaded by the motion control module and displays them.

8. The multi-axis sample stage closed-loop control system according to claim 7, characterized in that: The single-axis drive module includes a first microcontroller, a motor drive module, a limit switch detection module, a position sensor detection module, and a first power supply module; The first microcontroller is used to parse the communication instructions sent by the motion control module, control the speed, direction, and steps of the motor through the motor drive module, and receive the data from the limit switch detection module and the position sensor detection module; The limit switch detection module is used to determine the limit positions of each motion axis; The position sensor detection module is used to detect the motion position of each axis in real time and feedback it to the first microcontroller; The first power supply module is used to supply power to the first microcontroller, the motor drive module, the limit switch detection module, and the position sensor detection module.

9. The multi-axis sample stage closed-loop control system according to claim 7, characterized in that: The motion control module includes a second microcontroller, a first communication module, a second communication module, and a second power supply module; The second microcontroller includes an instruction parsing module, a motion planning module, and a state detection module. The instruction parsing module is used to parse the multi-axis motion instructions from the host computer received through the first communication module. The motion planning module is used to determine the motion speed, motion direction, and motion steps of each axis according to the pre-calibrated motion parameters of each axis, and send instructions to the single-axis drive module through the second communication module; The state detection module is used to analyze the single-axis real-time position and the motion state parameters of the motor uploaded by the single-axis drive module received through the second communication module, and upload the analysis results to the host computer through the first communication module; The second power supply module is used to supply power to the second microcontroller, the first communication module, and the second communication module.

10. The multi-axis sample stage closed-loop control system according to claim 7, characterized in that: The host computer includes a main control module, a user interaction module, and a third communication module; The user interaction module is used to receive the sample stage motion control instructions input by the user; The main control module is used to analyze the selected exercise mode of the user, convert it into multi-axis motion instructions, and send them to the motion control module through the third communication module. At the same time, it receives the motion parameters and positions of each axis of the sample stage uploaded by the motion control module and displays them on the user interaction module.

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