Device and method for measuring compensation amount of pipette stepper motor

Abstract

The present invention discloses a device and method for measuring the compensation amount of a pipette stepping motor, which includes an induction module, a moving module and a micro-control module. The moving module is connected to the output shaft of the stepping motor, and this connection relationship converts the rotational motion of the stepping motor into the linear motion of the moving module. The number of rotations of the stepping motor is in a proportional relationship with the moving distance of the moving module. The induction module and the stepping motor are respectively electrically connected to the micro-control unit. The micro-control module is used to control the stepping motor and compensate the stepping motor. The induction module is used to determine whether the moving module has moved in place and judge whether the stepping motor needs compensation, and determine the specific number of pulses that need to be compensated through the cooperation of the induction module and the moving module. The present invention has the advantages of wide application range, flexible application according to different occasions, high compensation accuracy, avoiding calculating the compensation amount by measuring the relationship between the angular velocity and current of the stepping motor from the inside of the stepping motor, and realizing simple closed-loop control.

Description

Technical Field

[0001] The present invention relates to the field of motor control, and particularly to a device and method for measuring the compensation amount of a pipette stepper motor. Background Art

[0002] With the development of computer control systems, stepper motors are divided into two types: open-loop control and closed-loop control. The fundamental difference between open-loop and closed-loop lies in whether to feedback the current operating state signal. The open-loop has no feedback signal, so it only executes in sequence, while the closed-loop has a feedback signal. According to the feedback signal, the stepper motor driver takes corresponding action measures or feeds the feedback signal back to the PLC, and the PLC decides the next program processing. Under open-loop control, the stepper motor is controlled by a pulse sequence with time intervals, without a feedback signal and corresponding electronic circuits. Although this control is simple and low-cost, it is prone to problems such as resonance, oscillation, out-of-step, and difficulty in achieving high speed, and the positioning accuracy is relatively low; while using closed-loop control, a higher operating speed than open-loop control can be obtained, with a more stable and smoother rotational speed and high positioning accuracy.

[0003] In actual use, the stepper motor adopts a closed-loop control system to enable the stepper motor to replace expensive servo motors in some cases. In the stepper motor closed-loop control system, generally, the motor shaft at the tail of the motor is lengthened, and an additional encoder and encoder housing are installed to measure the angular displacement of the stepper motor for positioning the stepper motor. For example, the patent with the patent number CN201811211169.6 discloses a method and device for compensating the rotation angle of a stepper motor, including: determining the angle turned by the stepper motor and the electrical rotation angle of the stepper motor; obtaining the current angular frequency of the stepper motor and determining the compensation angle; wherein, the corresponding relationship between the current angular frequency and the compensation angle is for each preset current signal. Using this current signal to control the operation of the stepper motor, adjusting the compensation angle according to a preset step size, and when the rotational speed of the stepper motor is the maximum, recording the corresponding relationship between the current angular frequency and the compensation angle and saving it; compensating the electrical rotation angle with the compensation angle. Since for each preset current signal, using this current signal to control the operation of the stepper motor, adjusting the compensation angle according to a preset step size, and when the rotational speed of the stepper motor is the maximum, recording the corresponding relationship between the current angular frequency and the compensation angle.

[0004] However, this structure damages the overall structure of the motor, resulting in a change in the motor size and an increase in volume. Although the cost is reduced compared to servo motors and the positioning of the stepper motor is achieved, due to the use of a lengthened motor shaft and encoder housing, the motor has a large volume, which is not conducive to the flexible installation and use of the stepper motor and limits the application range of the stepper motor. For example, in the medical field, in the use of pipettes, etc.; and when determining the compensation amount of the stepper motor, it is achieved by measuring the relationship between the angular velocity and current of the stepper motor, and the measurement process is complex, troublesome and not clear.

[0005] In the actual use process, especially in the medical field, for example, in the hospital's testing and laboratory department, a large number of blood samples or urine samples need to be detected and analyzed every day. To detect and analyze these samples, detection equipment is generally required, and corresponding chemical detection agents need to be added during the process. Generally, the corresponding chemical detection agent needs to be dropped into the vessel (such as a test tube) containing the biological liquid to cause a chemical reaction between the chemical detection agent and the biological liquid to be detected, so as to complete the detection of relevant indicators. Correspondingly, a pipette is often needed. The pipette is used to accurately drip a certain chemical reagent, so the accuracy requirement for the movement of the pipette is high. And in order to make the movement of the pipette more convenient, the requirements for the compensation and size of its motor are high. For example, in the patent No. CN215917445, a pneumatic pipette with an independent moving device is disclosed, which includes a pipette and a moving device. The pipette and the moving device are connected, and the moving device and the bracket are connected. The pipette is installed on the bracket through the moving device. The moving device includes a housing, a driving component and a connecting rod component. The driving component is installed at one end of the housing, and the connecting rod component is installed in the housing and one end of the connecting rod component passes through the housing and is connected to the driving component; one side of the housing is connected to the bracket, and the pipette is arranged on the side of the housing away from the bracket and is connected to the connecting rod component; a first limiting groove is opened in the housing, the connecting rod component is arranged in the first limiting groove, an avoidance opening is opened on the side of the housing close to the pipette, and the connecting rod component passes through the avoidance opening and is connected to the pipette, and the pipette can move up and down along the height direction of the avoidance opening. In this device, a stepper motor with a small size and high compensation accuracy is required to act as the driving component. Summary of the Invention

[0006] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a device and method for measuring the compensation amount of a pipette stepper motor, which uses a photoelectric sensor to measure the compensation amount required by the stepper motor in the stepper motor control system, avoids measuring the relationship between the angular velocity and current of the stepper motor from the inside of the stepper motor, converts the rotational motion of the stepper motor into a more clear and straightforward linear motion, so as to realize more convenient measurement of the compensation amount of the stepper motor and achieve a simple closed-loop control.

[0007] The purpose of the present invention is achieved by the following technical solutions:

[0008] A device for measuring the compensation amount of a pipette stepper motor, comprising an induction module, a moving module and a micro-control module. The moving module is connected to the output shaft of the stepper motor, and this connection relationship converts the rotational motion of the stepper motor into the linear motion of the moving module. The number of rotations of the stepper motor is in a proportional relationship with the moving distance of the moving module. The induction module and the stepper motor are respectively electrically connected to the micro-control unit. The micro-control module is used to control the stepper motor and compensate the stepper motor. The induction module is used to determine whether the moving module has moved in place and judge whether the stepper motor needs compensation, and determine the specific number of pulses to be compensated through the cooperation between the induction module and the moving module.

[0009] The induction module, the moving module and the stepper motor are all installed on the mounting base plate.

[0010] The micro-control module, also known as a single-chip microcomputer or a microcontroller, appropriately reduces the frequency and specifications of the central processing unit, and integrates peripherals such as memory, counter, USB, A / D conversion, UART, PLC, DMA, and even the LCD drive circuit on a single chip to form a chip-level computer, and makes different combined controls for different application scenarios.

[0011] The induction module includes a number of photoelectric sensors. The number of photoelectric sensors is connected to the mounting base plate along the length direction of the mounting base plate, and the photoelectric sensors are electrically connected to the micro-control module.

[0012] The moving module includes a sliding guide rail, a lead screw, a mounting seat and a grooved trigger piece. The sliding guide rail is arranged on the mounting base plate. One end of the lead screw is connected to the output shaft of the stepper motor through a coupling, and the other end of the lead screw is rotatably connected to the mounting base plate through a bearing. The sliding direction of the sliding guide rail, the length direction of the lead screw and the arrangement direction of the photoelectric sensors are parallel to each other. The mounting seat is slidably connected to the sliding guide rail, and the mounting seat is connected to the lead screw through a lead screw nut. The grooved trigger piece is installed on the mounting seat and cooperates with the photoelectric sensor. The grooved trigger piece is provided with a plurality of notches with the same spacing and width, and the notches cooperate with the photoelectric sensors to trigger the photoelectric sensors, and the width of the notches and the distance between adjacent notches are the same.

[0013] A method for measuring the compensation amount of a pipette stepper motor, the method comprising:

[0014] S1. Determine the number of pulses N required for the stepper motor to rotate one week under normal conditions, the distance S that the stepper motor drives the moving module to move linearly when rotating one week under normal conditions, and the unit distance A that the moving module moves when triggering the induction module once;

[0015] S2. Set the number of pulses sent as N m , where N m ≥N. According to step S1, the number of times the induction module should be triggered is T m times, and the distance that the moving module should move is S m , where T m = S m / A, T m is a positive integer. When the stepper motor has received N m pulses, determine whether the stepper motor needs compensation according to whether the actual number of times the induction module is triggered reaches T m times. If the actual number of times the induction module is triggered reaches T m times, the stepper motor does not need compensation. If the actual number of times the induction module is triggered does not reach T m times, the stepper motor has lost steps and needs compensation, and continue to send Δ pulses until the induction module is triggered T m times;

[0016] S3. Determine the one-time compensation amount of the stepper motor according to step S2, that is, the number of pulses corresponding to the stepper motor losing steps is Δ, and complete the compensation of the stepper motor through the control module.

[0017] Further, in step S2, N m / N = S m / S = n, n is a positive integer, and the number of times the induction module should be triggered T = S m / A = nS / A.

[0018] Further, the distance X that the moving module should move per unit pulse number = S m / N m = nS / N m = nT m A / N m , the value of S is 0 < S ≤ 6 mm, and the value of A is 0 < A ≤ 4 mm. Among them, when the value of A remains unchanged, the smaller the value of S, the smaller the value of X, and the higher the compensation accuracy of the stepper motor; when the value of S remains unchanged, the smaller the value of A, the m larger T is, the smaller the number of pulses corresponding to triggering an optoelectronic inductor once is, the smaller the distance that the corresponding grooved trigger piece moves is, and the higher the compensation accuracy of the stepper motor is.

[0019] The beneficial effects of the present invention are:

[0020] The grooved trigger piece and the photoelectric switch form a closed-loop control system, which can calibrate and compensate the position of the stepping motor in real time, effectively avoid external interference, and make the control of the whole movement process stable and reliable. It can be flexibly applied in different occasions. By setting the length of the grooved trigger piece, the width of the notch and the distance between adjacent photoelectric sensors, different positioning and compensation accuracies can be adjusted. Compared with the closed-loop control system formed by a stepping motor with a feedback encoder, it is simpler, can be automatically and effectively accelerated and decelerated, has higher efficiency and lower price, and has a wider and more flexible application range. Description of the Drawings

[0021] Figure 1 It is a schematic structural diagram of a device for measuring the compensation amount of a pipette stepping motor;

[0022] Figure 2 It is a flowchart of a method for measuring the compensation amount of a pipette stepping motor.

[0023] Explanation of the reference numerals in the drawings:

[0024] 1 - mounting base plate, 2 - circuit board, 3 - photoelectric sensor, 4 - lead screw, 5 - sliding guide rail, 6 - mounting seat, 7 - lead screw nut, 8 - grooved trigger piece, 9 - mounting positioning hole, 10 - stepping motor. Detailed Embodiment

[0025] The technical solution of the present invention will be further described in detail below with reference to the drawings, but the protection scope of the present invention is not limited to the following.

[0026] Please refer to Figure 1 and Figure 2 As shown, a device for measuring the compensation amount of a pipette stepping motor includes an induction module, a moving module and a micro-control module. The moving module is connected to the output shaft of the stepping motor, and this connection relationship converts the rotational motion of the stepping motor into the linear motion of the moving module to determine the proportional relationship between the number of rotations of the stepping motor and the moving distance of the moving module. The induction module is used to determine whether the moving module has moved in place and to judge whether the stepping motor needs compensation, and to determine the specific number of pulses to be compensated through the cooperation of the induction module and the moving module. The micro-control module is electrically connected to the induction module and the stepping motor respectively, and the micro-control module is used to control the stepping motor and compensate the stepping motor.

[0027] The induction module, the moving module and the stepping motor are all installed on the mounting base plate 1.

[0028] The micro-control module, also known as a single-chip microcomputer or microcontroller, reduces the frequency and specifications of the central processing unit appropriately and integrates peripherals such as memory, counter, USB, A / D conversion, UART, PLC, DMA, and even the LCD driver circuit on a single chip, forming a computer at the chip level to perform different combined controls for different application scenarios.

[0029] The induction module includes a number of photoelectric sensors 3. The number of photoelectric sensors 3 is connected to the mounting base 1 along the length direction of the circuit board. The photoelectric sensors 3 are electrically connected to the micro-control module.

[0030] Preferably, the number of photoelectric sensors 3 is connected to the mounting base 1 through the circuit board 2. The number of the circuit boards 2 is installed in series linearly on the mounting base 1. A number of photoelectric sensors 3 are evenly arranged on each circuit board 2. The number of photoelectric sensors 3 is evenly installed on the circuit board 2 along the length direction of the circuit board 2. The photoelectric sensors 3 are electrically connected to the micro-control module.

[0031] The moving module includes a sliding guide rail 5, a lead screw 4, a mounting seat 6, and a grooved trigger piece 8. The sliding guide rail 5 is arranged on the mounting base 1. One end of the lead screw 4 is connected to the output shaft of the stepping motor through a coupling, and the other end of the lead screw 4 is rotatably connected to the mounting base 1 through a bearing. The sliding direction of the sliding guide rail 5, the length direction of the lead screw 4, and the arrangement direction of the photoelectric sensors 3 are parallel to each other. The mounting seat 6 is slidably connected to the sliding guide rail 5, and the mounting seat 6 is connected to the lead screw 4 through a lead screw nut 7. The grooved trigger piece 8 is installed on the mounting seat 6 and cooperates with the photoelectric sensors 3. The grooved trigger piece 8 is provided with a plurality of notches with the same spacing and width. The notches cooperate with the photoelectric sensors 3 to trigger the photoelectric sensors 3, and the width of the notches and the distance between adjacent notches are the same.

[0032] Specifically, when the stepping motor rotates, through the transmission of the lead screw 4 and the lead screw nut 7, the rotational motion of the stepping motor is converted into the linear motion of the mounting seat 6 and the grooved trigger piece 8. At the same time, through the cooperation of the sliding guide rail 5 and the mounting seat 6, the sliding guide rail 5 plays a guiding role when the mounting seat 6 moves, making the movement of the grooved trigger piece 8 more stable. The width of the notches, the distance between adjacent notches, the distance between adjacent photoelectric sensors 3 on the same circuit board 2, and the lead of the lead screw 4 are all determined values. That is, by setting the specific sizes of these determined values, it can be calculated whether the stepping motor reaches the required compensation standard and the number of pulses to be compensated.

[0033] Specifically, in actual use, there are no requirements for the length of the grooved trigger piece 8 and the distance between the two photoelectric sensors 3. However, according to different application scenarios, the length of the grooved trigger piece 8 can be appropriately selected so that the length of the grooved trigger piece 8 is greater than or equal to the distance between adjacent photoelectric sensors 3 on the same circuit board 2; or the length of the grooved trigger piece 8 is less than the distance between adjacent photoelectric sensors 3 on the same circuit board 2. Specifically: when the length of the grooved trigger piece 8 is greater than or equal to the distance between adjacent photoelectric sensors 3 on the same circuit board 2, since the grooved trigger piece 8 and the photoelectric sensor 3 are always in a state of mutual induction, that is, the stepper motor is constantly measuring the compensation amount and making corresponding compensations. This situation is applicable to movements that require high-precision positioning throughout the entire movement process, such as curvilinear movement, circular movement, or pipettes in the medical field. When the length of the grooved trigger piece 8 is less than the distance between adjacent photoelectric sensors 3 on the same circuit board 2, there will be a situation where the photoelectric sensor 3 cannot sense the grooved trigger piece 8 for a period of time, that is, the stepper motor is not constantly measuring the compensation amount but is in an intermittent compensation state. The positioning accuracy is slightly lower than the above method. This situation is applicable to movements that only have positioning and compensation requirements for part of the stroke.

[0034] Specifically, the distances between adjacent photoelectric sensors 3 on multiple circuit boards 2 can be the same or different; preferably, as Figure 1 shown, in this embodiment, there are two circuit boards 2, and the two circuit boards 2 are arranged in a straight line. The distance between adjacent photoelectric sensors 3 on one circuit board 2 is greater than the length of the grooved trigger piece 8, and the distance between adjacent photoelectric sensors 3 on the other circuit board 2 is less than the length of the grooved trigger piece 8. According to the actual application situation, different positioning and compensation accuracies can be correspondingly selected, and the application is more flexible. At the same time, the smaller the width of the slot, the higher the calibration accuracy, and the longer the length of the grooved trigger piece 8, the fewer the photoelectric sensors 3 used, and the better the stability and system dynamic response.

[0035] Specifically, mounting positioning holes 9 are provided at the four corners of the circuit board 2, and the circuit board 2 and the photoelectric sensor 3 are of an integral structure. By cooperating with the mounting base plate 1 through the mounting positioning holes 9, it is convenient for the quick positioning and installation of the circuit board 2 and the photoelectric sensor 3.

[0036] In another embodiment, as Figure 2 shown, a method for measuring the compensation amount of a pipette stepper motor, the method includes the following steps:

[0037] S1. Determine the number of pulses N required for the stepper motor to rotate one week under normal conditions, the distance S that the stepper motor drives the moving module to move linearly when rotating one week under normal conditions, and the unit distance A that the moving module moves when triggering the sensing module once;

[0038] S2. Set the number of pulses sent as N m , where N m ≥N. According to step S1, the number of times the induction module should be triggered is T m times, and the distance that the moving module should move is S m , where T m =S m / A, T m is a positive integer. When the stepper motor has received N m pulses, it is determined whether the stepper motor needs compensation according to whether the actual number of times the induction module is triggered reaches T m times. If the actual number of times the induction module is triggered reaches T m times, the stepper motor does not need compensation. If the actual number of times the induction module is triggered does not reach T m times, the stepper motor has lost steps and needs compensation, and continue to send Δ pulses until the induction module is triggered T m times;

[0039] S3. Determine the one-time compensation amount of the stepper motor according to step S2, that is, the number of pulses corresponding to the stepper motor losing steps is Δ, and complete the compensation of the stepper motor through the control module.

[0040] Specifically, in step S2, N m / N = S m / S = n, n is a positive integer, and the number of times the induction module should be triggered T m =S m / A = nS / A, and the distance X that the moving module should move per unit pulse number = S m / N m = nS / N m = nT m A / N m , where the smaller the value of S, the smaller the value of X, and the higher the compensation accuracy of the stepper motor; the smaller the value of A, the larger the number of times T m that the photoelectric inductor 3 should be triggered, that is, the fewer the number of pulses corresponding to a single trigger, and the higher the compensation accuracy of the stepper motor. In the medical field, for example, in the use of a pipette, generally n is 1, 0 < S ≤ 6 mm, and 0 < A ≤ 4 mm are the optimal range values.

[0041] Preferably, such as Figure 1As shown, in the field of medical devices, when applied to a pipette, the length of the grooved trigger piece 8 is less than 26 mm and less than or equal to the distance between two adjacent photoelectric sensors 3. That is, when the pipette is working, the stepper motor is always in a compensation state, ensuring the accuracy of the pipette movement; the lead of the lead screw 4, i.e., S, is less than or equal to 6 mm; the width of the notch and the distance between two adjacent notches, i.e., A, are both less than or equal to 4 mm; set the S m = S = 4 mm, N m = N = 200, that is, the lead of the lead screw 4 is 4 mm. Before the stepper motor 10 rotates, the photoelectric sensor 3 is aligned with the end or tail of the notch. When the stepper motor 10 rotates one week, the grooved trigger piece 8 is linearly moved forward 4 mm through the lead screw 4. Since the width of the notch and the distance between two adjacent notches are both 2 mm, that is, A = 2 mm, when the grooved trigger piece 8 moves forward 4 mm, that is, when the stepper motor rotates one week, the photoelectric sensor 3 is blocked by the grooved trigger piece 8 from being blocked to unblocked and then blocked again, or from unblocked to blocked and then unblocked again, thereby triggering the photoelectric sensor 3 2 times, enabling the stepper motor to trigger the photoelectric sensor 3 2 times per revolution without losing steps, and thus determining the relationship between the number of rotation cycles and the number of trigger times of the photoelectric sensor 3 during the operation of the stepper motor. Conduct a test, and the test results are shown in Table 1:

[0042] Table 1 Test results table of stepper motor compensation

[0043]

[0044] It can be seen from Table 1 that the smaller the value of the lead of the lead screw 4, i.e., S, the smaller the distance that the grooved trigger 8 moves corresponding to a unit pulse, and the higher the compensation accuracy of the stepper motor. The smaller the value of the width of the notch, i.e., A, the more times the photoelectric sensor 3 should be triggered, that is, the fewer the number of pulses corresponding to triggering the photoelectric sensor 3 once, and the smaller the distance that the grooved trigger 8 moves corresponding to it, and the higher the compensation accuracy of the stepper motor.

[0045] Preferably, since T m = S m / A may result in a situation where T m is not an integer. At this time, due to the uncertainty of T m , it will greatly affect the determination of the compensation amount. Therefore, generally, by taking appropriate values of S m and A, ensure that T m is a positive integer, especially in the medical field that requires high precision, such as the use of a pipette.

[0046] The above are only the preferred embodiments of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein, should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be changed within the scope of the concept described herein through the above teachings or the technology or knowledge in the relevant field. And the changes and modifications made by those skilled in the art without departing from the spirit and scope of the present invention should fall within the protection scope of the appended claims of the present invention.

Claims

1. A device for measuring the compensation amount of a pipette stepper motor, characterized in that, It includes an induction module, a moving module and a micro-control module. The moving module is connected to the output shaft of the stepping motor. This connection relationship converts the rotational motion of the stepping motor into the linear motion of the moving module. The number of rotations of the stepping motor is in a proportional relationship with the moving distance of the moving module. The induction module and the stepping motor are respectively electrically connected to the micro-control unit. The micro-control module is used to control the stepping motor and compensate the stepping motor. The induction module is used to determine whether the moving module has moved in place and judge whether the stepping motor needs compensation, and determine the specific number of pulses to be compensated through the cooperation between the induction module and the moving module; The moving module includes a sliding guide rail, a lead screw, a mounting seat and a grooved trigger piece. The sliding guide rail is arranged on the mounting base plate. One end of the lead screw is connected to the output shaft of the stepping motor through a coupling, and the other end of the lead screw is rotatably connected to the mounting base plate through a bearing. The sliding direction of the sliding guide rail, the length direction of the lead screw and the arrangement direction of the photoelectric sensors are parallel to each other. The mounting seat is slidably connected to the sliding guide rail and is connected to the lead screw through a lead screw nut. The grooved trigger piece is mounted on the mounting seat and cooperates with the photoelectric sensor; The grooved trigger piece is provided with a plurality of notches with the same spacing and width. The notches cooperate with the photoelectric sensors to trigger the photoelectric sensors, and the width of the notches and the distance between adjacent notches are the same; the length of the grooved trigger piece is less than 26 mm and less than or equal to the distance between two adjacent photoelectric sensors; the lead of the lead screw S is less than or equal to 6 mm; the width of the notch and the distance A between two adjacent notches are both less than or equal to 4 mm.

2. The device for measuring the compensation amount of the pipette stepping motor according to claim 1, wherein: The induction module, the moving module and the stepping motor are all mounted on the mounting base plate.

3. The device for measuring the compensation amount of the pipette stepping motor according to claim 2, wherein: The induction module includes a plurality of photoelectric sensors. The plurality of photoelectric sensors are connected to the mounting base plate along the length direction of the mounting base plate, and the photoelectric sensors are electrically connected to the micro-control module.

4. A method for measuring the compensation amount of a pipette stepper motor, based on the device for measuring the compensation amount of a pipette stepper motor described in claim 1, characterized in that: The method includes: S1. Determine the number of pulses N required for the stepping motor to rotate one week under normal conditions, the distance S that the stepping motor drives the moving module to move linearly when rotating one week under normal conditions, and the unit distance A that the moving module moves when triggering the induction module once; S2. Set the number of pulses to be sent as N m , where N m ≥N. According to step S1, the number of times the induction module should be triggered is T m times, and the distance that the moving module should move is S m , where T m = S m / A, T m is a positive integer. When the stepper motor has received N m pulses, determine whether the stepper motor needs compensation according to whether the actual number of times the induction module is triggered reaches T m times. If the actual number of times the induction module is triggered reaches T m times, the stepper motor does not need compensation. If the actual number of times the induction module is triggered does not reach T m times, the stepper motor has lost steps and needs compensation, and continue to send Δ pulses until the induction module is triggered T m times; S3. Determine the one-time compensation amount of the stepping motor according to step S2, that is, the number of pulses corresponding to the stepping motor losing steps is Δ, and complete the compensation of the stepping motor through the control module; In step S2, N m / N = S m / S = n, where n is a positive integer; The distance X that the moving module should move at the number of unit pulses = S m / N m = nS / N m = T m A / N m , where the value of S is 0 < S ≤ 6 mm, and the value of A is 0 < A ≤ 4 mm.

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