An Automatic Liquid Injection / Suction Device and Method Based on Visual Servo Control

Abstract

The present invention discloses a liquid automatic injection / aspiration device and method based on visual servo control, comprising: an electric injection / aspiration module; a visual monitoring module for acquiring an image of a pipette and obtaining the historical liquid level scale position inside the pipette based on the visual monitoring module; a data processing module for predicting the liquid level scale position at the next moment based on the historical liquid level scale position; obtaining the liquid level scale position at the next moment through the pipette image at the next moment, subtracting the liquid level scale position at the next moment from the predicted liquid level scale position at the next moment, and adjusting the motor speed at the next moment based on the difference value. The present invention combines a visual monitoring method and a motor control method, controls the operation of the motor based on the image data monitored by vision, is not affected by the environment and the type of liquid, and does not require repeated calibration, realizing the upgrade of the injector from electrification to intelligence.

Description

Technical Field

[0001] The present invention relates to the technical field of automatic liquid injection / suction, and in particular to an automatic liquid injection / suction device and method based on visual servo control. Background Art

[0002] The statements in this part only provide background technical information related to the present invention and do not necessarily constitute prior art.

[0003] Syringes (or pipettes) are commonly used equipment in biological and chemical laboratories, widely used in quantitative transfer and proportioning of liquid reagents, etc., and are indispensable tools in experimental operations and drug production processes. Syringes can be divided into three stages according to the degree of automation: traditional rubber-tipped droppers with scales, semi-automatic syringes, and fully automatic syringes. Among them, semi-automatic and fully automatic syringes are both electric modes, relying on motors to drive injection / suction pumps to complete the functions of liquid injection and suction. The semi-automatic syringe controls the rotation time of the motor through physical buttons, and the volume of injected / sucked liquid needs to be observed manually; the fully automatic syringe only needs to preset the liquid volume and can automatically complete quantitative liquid injection / suction according to the previously calibrated data. Since electric syringes have higher accuracy and stability than traditional pipettes, they have become the current mainstream method.

[0004] However, currently existing electric injection / suction devices mainly rely on the rotation time of the motor to control the amount of liquid injection / suction. When factors such as liquid type and external temperature change, the previously calibrated time becomes inaccurate. Therefore, frequent calibration is required to maintain the accuracy of liquid injection / suction, which requires high experience from the operator and is not very convenient to operate. Summary of the Invention

[0005] To solve the above problems, the present invention proposes an automatic liquid injection / suction device and method based on visual servo control. Based on visual monitoring and servo control methods, it can adaptively control the on / off and speed of the motor, is not affected by the external environment and liquid types, and does not require repeated calibration.

[0006] In some embodiments, the following technical solutions are adopted:

[0007] An automatic liquid injection / suction device based on visual servo control, comprising:

[0008] An electric injection / suction module, the electric injection / suction module comprising: a diaphragm pump, a motor, and an air circuit; the motor is connected to the diaphragm pump, and the diaphragm pump is respectively connected to a first air circuit and a second air circuit; the first air circuit is connected to the outside, and the second air circuit is connected to a graduated pipette; two one-way conduction solenoid valves are respectively provided on the first air circuit and the second air circuit, and the conduction directions of the two one-way conduction solenoid valves are opposite;

[0009] A visual monitoring module, configured to acquire an image of a pipette and obtain the historical liquid level scale position inside the pipette based on the visual monitoring module;

[0010] A data processing module, configured to predict the liquid level scale position at the next moment based on the historical liquid level scale position; obtain the liquid level scale position at the next moment through the image of the pipette at the next moment, calculate the difference between the liquid level scale position at the next moment and the predicted liquid level scale position at the next moment, and adjust the motor speed at the next moment based on the difference.

[0011] The diaphragm pump constructs a cavity capable of containing gas through a thin film, and drives the diaphragm to move back and forth through a motor. The back-and-forth movement of the diaphragm can drive the change of the gas volume in the cavity, thereby generating positive pressure or negative pressure.

[0012] When the pipette sucks in liquid, if the diaphragm pump cavity generates negative pressure, the second gas path channel is opened by controlling the solenoid valve, so that the negative pressure drives the gas in the second gas path to be pumped inward, thereby generating an inward suction force in the pipette; if the diaphragm pump cavity generates positive pressure, the first gas path channel is opened by controlling the solenoid valve to discharge the gas.

[0013] When the pipette injects liquid outward, if the diaphragm pump cavity generates negative pressure, the first gas path channel is opened by controlling the solenoid valve, so that the gas is sucked in from the first gas path; if the diaphragm pump cavity generates positive pressure, the second gas path channel is opened by controlling the solenoid valve, so that an outward thrust is generated in the pipette to push out the liquid in the pipette.

[0014] The visual monitoring module includes:

[0015] An imaging unit, configured to acquire an image of the pipette;

[0016] An image processing unit, configured to obtain the historical liquid level scale position inside the pipette based on the visual monitoring module; specifically: acquire an image of the pipette, identify the scale lines on the pipette through image segmentation, and calculate the pixel distance corresponding to the scale lines in the pixel coordinate system; according to the pipette model information, obtain the volume value represented by each scale line, realize the correspondence between the pixel coordinates and the physical coordinates, and thereby calculate the volume value corresponding to each pixel coordinate;

[0017] The image of the pipette is sequentially subjected to graying, denoising, smoothing and binarization processing, and the boundary line of the segmentation region is extracted, which is the liquid level line; obtain the position of the liquid level line in the pixel coordinate system, and further calculate the liquid level scale value inside the pipette.

[0018] In some other embodiments, the following technical solutions are adopted:

[0019] A method for automatic liquid injection / suction based on visual servo control, including:

[0020] The diaphragm of the diaphragm pump is driven by a motor to move back and forth. The back-and-forth movement of the diaphragm can drive the change of the gas volume in the cavity of the diaphragm pump, thereby generating positive pressure or negative pressure, realizing the automatic injection or suction of the pipette, and the automatic suction or discharge of gas;

[0021] Among them, an image of the pipette is acquired, and the historical liquid level scale position in the pipette is obtained based on the visual monitoring module; the liquid level scale position at the next moment is predicted based on the historical liquid level scale position; the liquid level scale position at the next moment is obtained through the pipette image at the next moment, and the liquid level scale position at the next moment is subtracted from the predicted liquid level scale position at the next moment, and the motor speed at the next moment is adjusted based on the difference.

[0022] Among them, predicting the liquid level scale position at the next moment based on the historical liquid level scale position is specifically:

[0023] When the liquid in the pipette starts to flow, images of the pipette are acquired at a set frequency, the scale position of the liquid level in the pipette at each moment is recognized based on the images of the pipette, and the data is stored as the historical liquid level scale position at each moment;

[0024] Based on the difference between the liquid level scale positions obtained at two set moments, the average moving speed of the liquid level in the time period corresponding to the two moments is calculated;

[0025] Based on the liquid level scale position at the current moment and the average moving speed of the liquid level, the liquid level scale position at the next moment is predicted.

[0026] When the difference is less than the set threshold, the motor speed is controlled to remain stable; when the liquid level in the pipette reaches the preset requirement, the motor is controlled to stop rotating.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] (1) The present invention combines the visual monitoring method and the motor control method, and controls the operation of the motor based on the image data monitored by vision, which is not affected by the environment and the type of liquid, and does not require repeated calibration, realizing the upgrade of the injector from electrification to intelligence.

[0029] (2) The present invention uses machine vision to identify the liquid level scale at different moments, can obtain the moving speed of the liquid level, and then predict the liquid level scale at the next moment; based on the difference between the detected liquid level scale at the next moment and the predicted liquid level scale at the next moment, feedback control is performed on the motor, which can automatically and accurately control the amount of liquid inhaled or injected into the pipette, avoiding the influence of the external environment and liquid concentration on the injection / suction (injection or suction) accuracy; nor is it necessary to perform repeated calibration, and the professional requirements for the operator are not high.

[0030] (3) Both the first gas path and the second gas path channel of the present invention adopt two-way flow branches, and each branch is provided with a solenoid valve for one-way flow, which can control the opening and closing of the solenoid valve as needed to achieve the conduction and closing of different branches; automatic control of the gas path conduction can be realized, making it more suitable for automated systems and facilitating integration with other devices.

[0031] (4) The present invention can be used alone as an automated device or in an unmanned laboratory system to undertake the full-automatic liquid reagent transfer operation tasks in biological, chemical experiments or drug preparation production processes.

[0032] Other features and advantages of the additional aspects of the present invention will be partially given in the following description, partially become obvious from the following description, or be understood through the practice of this aspect. Description of the Drawings

[0033] Figure 1 It is a schematic structural diagram of the liquid automatic injection / aspiration device based on visual servo control in the embodiment of the present invention;

[0034] Figure 2 It is a schematic structural diagram of the gas path in the embodiment of the present invention;

[0035] Figure 3 It is a flow chart of the liquid automatic injection / aspiration method based on visual servo control in the embodiment of the present invention;

[0036] Figure 4 It is a schematic diagram of the motor control process in the embodiment of the present invention;

[0037] Among them, 1. Electric injection / aspiration module; 2. Camera unit; 3. Data processing unit; 4. Pipette with scale; 5. Container for the liquid reagent to be transferred;

[0038] 1-1. Motor; 1-2. Diaphragm pump; 1-3. Eccentric wheel; 1-4. Gas path; 2-1. Image processing unit; 1-4-1. First intake channel solenoid valve; 1-4-2. First outlet channel solenoid valve; 1-4-3. Second outlet channel solenoid valve; 1-4-4. Second intake channel solenoid valve. Detailed Embodiments

[0039] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0040] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0041] Example 1

[0042] In one or more embodiments, a liquid automatic injection / suction device based on visual servo control is disclosed. In combination with Figure 1 , specifically including:

[0043] (1) Electric injection / suction (injection or suction) module. The electric injection / suction module 1 includes: a diaphragm pump 1-2, a motor 1-1, and a gas path 1-4; the motor 1-1 is connected to the diaphragm pump 1-2, and the diaphragm pump 1-2 is respectively connected to a first gas path and a second gas path; the first gas path is connected to the outside, and the second gas path is connected to a graduated pipette 4; the graduated pipette 4 corresponds to a container 5 for the liquid reagent to be transferred, and can suck out or inject liquid from the container.

[0044] Two one-way conduction solenoid valves are respectively provided on the first gas path and the second gas path, and the conduction directions of the two one-way conduction solenoid valves are opposite;

[0045] In this embodiment, a cavity that can accommodate gas is constructed by a soft film in the diaphragm pump. The motor 1-1 is connected to the film through an eccentric wheel 1-3 and is used to drive the film to move; the reciprocating movement of the diaphragm can drive the change of the gas volume in the cavity, generating positive pressure or negative pressure; thereby realizing the automatic injection or suction of the liquid in the pipette; and the automatic inhalation or discharge of gas.

[0046] Specifically, in combination with Figure 2 , the first gas path of this embodiment includes: a first intake channel solenoid valve 1-4-1 and a first outlet channel solenoid valve 1-4-2; the two solenoid valves are connected in parallel, dividing the first gas path into two branches, one is the intake branch and the other is the outlet branch.

[0047] Both solenoid valves are one-way conduction and do not conduct simultaneously, and the conduction directions are opposite. When the first intake channel solenoid valve is opened, the first outlet channel solenoid valve is closed, and external gas can enter the diaphragm pump from the intake branch of the first gas path. When the first intake channel solenoid valve is opened, the first outlet channel solenoid valve is closed, and external gas can be discharged from the diaphragm pump through the outlet branch of the first gas path.

[0048] Similarly, the second gas path includes: the second intake channel solenoid valve 1-4-4 and the second outlet channel solenoid valve 1-4-3; the two solenoid valves are connected in parallel, dividing the second path into two branches, one being the intake branch and the other being the outlet branch. Both solenoid valves conduct in one direction only, do not conduct simultaneously, and have opposite conduction directions. When the second intake channel solenoid valve is open, the second outlet channel solenoid valve is closed, and at this time, the liquid can be sucked into the pipette; when the second outlet channel solenoid valve is open, the second intake channel solenoid valve is closed, and at this time, the liquid can be injected out of the pipette.

[0049] In this embodiment, when the pipette sucks in liquid, if a negative pressure is generated in the diaphragm pump cavity, the second gas path channel is opened by controlling the solenoid valve, causing the negative pressure to drive the gas in the second gas path to be drawn inwards, thereby generating an inward suction force in the pipette; if a positive pressure is generated in the diaphragm pump cavity, the first gas path channel is opened by controlling the solenoid valve to discharge the gas.

[0050] When the pipette injects liquid outwards, if a negative pressure is generated in the diaphragm pump cavity, the first gas path channel is opened by controlling the solenoid valve, causing the gas to be sucked in from the first gas path; if a positive pressure is generated in the diaphragm pump cavity, the second gas path channel is opened by controlling the solenoid valve, causing an outward thrust to be generated in the pipette to push the liquid in the pipette out.

[0051] (2) The visual monitoring module is used to acquire an image of the pipette and obtain the historical liquid level scale position in the pipette based on the visual monitoring module;

[0052] In this embodiment, the visual monitoring module includes:

[0053] The imaging unit 2 is used to acquire an image of the pipette; the imaging unit selects a general grayscale camera, which is used to collect the monitoring image of the pipette when the pipette is working, and its imaging range can cover the height of the entire graduated pipette.

[0054] The image processing unit 2-1 is used to obtain the historical liquid level scale position in the pipette based on the visual monitoring module; the specific process is as follows:

[0055] An image of the pipette is acquired through the grayscale camera, the scale lines on the pipette are recognized through image segmentation, and the pixel distance corresponding to the scale lines in the pixel coordinate system is calculated; according to the pipette model information, the volume value represented by each scale line is obtained, the correspondence between the pixel coordinates and the physical coordinates is realized, and thus the volume value corresponding to each pixel coordinate is calculated;

[0056] The image of the pipette is successively subjected to grayscale conversion, denoising, smoothing, and binarization to extract the boundary line of the segmented region, which is the liquid level line. In this embodiment, the image is obtained from the side of the pipette, and the liquid in the pipette appears as a long strip region in the image. When performing image recognition, the acquired pipette image is divided into a liquid region and a non-liquid region according to the color and grayscale of the image, and the boundary line between the two regions is the liquid level.

[0057] Obtain the position of the liquid level line in the pixel coordinate system, and then calculate the liquid level scale value inside the pipette; obtain the image of the pipette, and based on the visual monitoring module, obtain and store the liquid level scale positions at various historical moments inside the pipette.

[0058] (3) The data processing module is used to predict the liquid level scale position at the next moment based on the historical liquid level scale positions; obtain the liquid level scale position at the next moment through the pipette image at the next moment, calculate the difference between the liquid level scale position at the next moment and the predicted liquid level scale position at the next moment, and adjust the motor speed at the next moment based on the difference.

[0059] In this embodiment, the specific process of realizing motor control is as follows: obtain the image of the pipette, obtain and store the liquid level scale positions at historical moments inside the pipette based on the visual monitoring module; predict the liquid level scale position at the next moment based on the historical liquid level scale positions; obtain the liquid level scale position at the next moment through the pipette image at the next moment, calculate the difference between the liquid level scale position at the next moment and the predicted liquid level scale position at the next moment, and adjust the motor speed at the next moment based on the difference.

[0060] Specifically, in combination with Figure 4 , the motor is started at the default speed at the initial moment; according to the liquid level position and the liquid level moving speed V i at the T i moment given by the visual monitoring module, predict the liquid level position at the next moment (T i+1 moment); among them, the liquid level movement value in the pipette can be calculated based on two different historical pipette images, so as to calculate the average moving speed V i - V i-1 of the liquid level within the time period of T i . At the T i+1 moment, compare the actual liquid level position detected by the camera with the predicted position, calculate the deviation between the observed value and the predicted value, and output a control command to control the motor to accelerate or decelerate according to the deviation to adjust the motor speed; repeat this process. When the deviation is reduced to a certain range, the motor moves stably at the current speed; when the liquid injection / absorption volume reaches the preset value, turn off the motor.

[0061] Embodiment 2

[0062] In one or more embodiments, a liquid automatic injection / suction method based on visual servo control is disclosed, combined with Figure 3 , specifically including:

[0063] The diaphragm of the diaphragm pump is driven by a motor to move back and forth. The back-and-forth movement of the diaphragm can drive the change of the gas volume in the cavity of the diaphragm pump, thereby generating positive pressure or negative pressure, realizing the automatic injection or suction of the pipette, and the automatic suction or discharge of gas.

[0064] Among them, the specific motor control process is as follows:

[0065] (1) Obtain the image of the pipette, and obtain the historical liquid level scale position in the pipette based on the visual monitoring module; the specific process is:

[0066] When the liquid in the pipette starts to flow, collect the images of the pipette at a set frequency, identify the scale position of the liquid level in the pipette at each moment based on the images of the pipette, and store the data as the historical liquid level scale position at each moment;

[0067] Specifically, the visual monitoring module obtains the image of the pipette, identifies the scale lines on the pipette through image segmentation, and calculates the pixel distance corresponding to the scale lines in the pixel coordinate system; according to the pipette model information, obtain the volume value represented by each scale line, realize the correspondence between pixel coordinates and physical coordinates, and thus calculate the volume value corresponding to each pixel coordinate;

[0068] Perform gray scale, denoising, smoothing and binarization processing on the image of the pipette in turn, extract the boundary line of the segmented area, which is the liquid level line; obtain the position of the liquid level line in the pixel coordinate system, and then calculate the liquid level scale value in the pipette at each moment.

[0069] (2) Based on the difference between the liquid level scale positions obtained at two set moments, calculate the average moving speed of the liquid level in the time period corresponding to the two moments; for example: the liquid level movement value in the pipette can be calculated according to two different-time historical images of the pipette, so as to calculate the average moving speed V of the liquid level in the T i -T i-1 time period i .

[0070] (3) According to the liquid level scale position at the current moment and the average moving speed of the liquid level, predict the liquid level scale position at the next moment; specifically:

[0071] When the liquid in the pipette starts to flow, collect the images of the pipette at a set frequency, identify the scale position of the liquid level in the pipette at each moment based on the images of the pipette, and store the data as the historical liquid level scale position at each moment;

[0072] Calculate the average moving speed of the liquid level within the time period corresponding to the two moments based on the difference in the liquid level scale positions obtained at the two set moments.

[0073] Predict the liquid level scale position at the next moment based on the liquid level scale position at the current moment and the average moving speed of the liquid level.

[0074] Obtain the liquid level scale position at the next moment from the pipette image at the next moment, calculate the difference between the liquid level scale position at the next moment and the predicted liquid level scale position at the next moment, and adjust the motor speed at the next moment based on the difference.

[0075] When the difference is less than the set threshold, control the motor speed to remain stable; when the liquid level in the pipette reaches the preset requirement, control the motor to stop rotating.

[0076] As a specific example, the specific operation process of the liquid automatic injection / aspiration method based on visual servo control is as follows:

[0077] Taking the automatic liquid aspiration function as an example, the working process of this embodiment is described as follows:

[0078] The user logs in to the data processing module through the operation interface and preset the volume of liquid to be aspirated; the data processing module can select a central control unit.

[0079] Start the system, the grayscale camera collects the initial image of the pipette, and the image processing unit identifies the volume scale on the pipette.

[0080] Start the motor at the default speed to drive the eccentric wheel to rotate, thereby causing the diaphragm of the diaphragm pump to perform a piston motion through the connecting rod; when the diaphragm expands outward, a negative pressure is generated in the cavity of the diaphragm pump, the solenoid valve of the second intake passage of the second gas path is opened, and the negative pressure drives the gas in the second gas path to be drawn inwards, so that an inward suction force is generated in the pipette connected to the second gas path. When the diaphragm squeezes inward, the solenoid valve of the second intake passage is closed, and the solenoid valve of the first outlet passage is opened to discharge the gas to the outside of the device.

[0081] Similarly, when injecting liquid, switch to the solenoid valve of the second outlet passage and the solenoid valve of the first intake passage, inhale the external gas, and push out the liquid in the pipette to achieve gas path inversion.

[0082] During the liquid suction process, the grayscale camera continuously collects the images of the pipette, and the image processing unit calculates the rising position and rising speed of the liquid level.

[0083] The visual servo control program running on the image processing unit adaptively adjusts the motor speed according to the liquid level position given by the visual signal processing system to make it reach a stable speed.

[0084] When it is monitored that the liquid inhalation volume reaches the specified scale, stop the motor and close all solenoid valves in the gas circuit to maintain the air pressure in the pipeline and ensure that the liquid in the pipette will not flow out due to gravity.

[0085] Although the specific implementation manners of the present invention are described in conjunction with the accompanying drawings above, it is not a limitation to the protection scope of the present invention. Those skilled in the art should understand that various modifications or deformations that can be made without creative efforts on the basis of the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. An automatic liquid injection / suction device based on visual servo control, characterized in that, Comprising: An electric injection / aspiration module, which includes: a diaphragm pump, a motor, and a gas path; the motor is connected to the diaphragm pump, and the diaphragm pump is respectively connected to a first gas path and a second gas path; the first gas path is connected to the outside, and the second gas path is connected to a graduated pipette; two one-way conduction solenoid valves are respectively provided on the first gas path and the second gas path, and the conduction directions of the two one-way conduction solenoid valves are opposite; A visual monitoring module, which is used to obtain an image of the pipette and obtain the historical liquid level scale position in the pipette based on the visual monitoring module; A data processing module, which is used to predict the liquid level scale position at the next moment based on the historical liquid level scale position; obtain the liquid level scale position at the next moment through the image of the pipette at the next moment, calculate the difference between the liquid level scale position at the next moment and the predicted liquid level scale position at the next moment, and adjust the motor speed at the next moment based on the difference.

2. The liquid automatic injection / aspiration device based on visual servo control according to claim 1, characterized in that, The motor is connected to the diaphragm pump through an eccentric wheel.

3. The liquid automatic injection / aspiration device based on visual servo control according to claim 1, wherein, The diaphragm pump constructs a cavity capable of containing gas through a diaphragm. The motor drives the diaphragm to move back and forth, and the back-and-forth movement of the diaphragm can drive the volume of gas in the cavity to change, thereby generating positive pressure or negative pressure.

4. The liquid automatic injection / aspiration device based on visual servo control according to claim 3, wherein When the pipette sucks in liquid, if the cavity of the diaphragm pump generates negative pressure, the second gas path channel is opened by controlling the solenoid valve, so that the negative pressure drives the gas in the second gas path to be sucked inward, thereby generating an inward suction force in the pipette; if the cavity of the diaphragm pump generates positive pressure, the first gas path channel is opened by controlling the solenoid valve to discharge the gas.

5. The liquid automatic injection / suction device based on visual servo control according to claim 3, wherein When the pipette injects liquid outward, if the cavity of the diaphragm pump generates negative pressure, the first gas path channel is opened by controlling the solenoid valve, so that the gas is sucked in from the first gas path; if the cavity of the diaphragm pump generates positive pressure, the second gas path channel is opened by controlling the solenoid valve, so that an outward thrust is generated in the pipette to push out the liquid in the pipette.

6. The liquid automatic injection / aspiration device based on visual servo control according to claim 1, characterized in that, The visual monitoring module includes: An imaging unit, which is used to obtain an image of the pipette; An image processing unit, which is used to obtain the historical liquid level scale position in the pipette based on the visual monitoring module; specifically: obtain an image of the pipette, identify the scale lines on the pipette through image segmentation, and calculate the pixel distance corresponding to the scale lines in the pixel coordinate system; according to the pipette model information, obtain the volume value represented by each scale line, realize the correspondence between the pixel coordinates and the physical coordinates, and thus calculate the volume value corresponding to each pixel coordinate; Perform gray-scale, denoising, smoothing, and binarization processing on the image of the pipette in sequence, extract the boundary line of the segmentation area, which is the liquid level line; obtain the position of the liquid level line in the pixel coordinate system, and then calculate the liquid level scale value in the pipette.

7. A liquid automatic injection / suction method based on visual servo control, characterized in that, Comprising: The motor drives the diaphragm of the diaphragm pump to move back and forth. The back-and-forth movement of the diaphragm can drive the volume of gas in the cavity of the diaphragm pump to change, thereby generating positive pressure or negative pressure, realizing the automatic injection or aspiration of the pipette, and the automatic inhalation or discharge of gas; Among them, an image of the pipette is obtained, and the historical liquid level scale position in the pipette is obtained based on the visual monitoring module; the liquid level scale position at the next moment is predicted based on the historical liquid level scale position; the liquid level scale position at the next moment is obtained through the pipette image at the next moment, and the liquid level scale position at the next moment is subtracted from the predicted liquid level scale position at the next moment, and the motor speed at the next moment is adjusted based on the difference.

8. The liquid automatic injection / suction method based on visual servo control according to claim 7, wherein Predicting the liquid level scale position at the next moment based on the historical liquid level scale position specifically includes: When the liquid in the pipette starts to flow, images of the pipette are collected at a set frequency, the scale position of the liquid level in the pipette at each moment is identified based on the images of the pipette, and the data is stored as the historical liquid level scale position at each moment; Based on the difference in the liquid level scale positions obtained at two set moments, the average moving speed of the liquid level in the time period corresponding to the two moments is calculated; Based on the liquid level scale position at the current moment and the average moving speed of the liquid level, the liquid level scale position at the next moment is predicted.

9. The liquid automatic injection / suction method based on visual servo control according to claim 7, characterized in that When the difference is less than the set threshold, the motor speed is controlled to remain stable; when the liquid level in the pipette reaches the preset requirement, the motor is controlled to stop rotating.

10. A liquid automatic injection / suction method based on visual servo control according to claim 7, characterized in that Obtaining the historical liquid level scale position in the pipette based on the visual monitoring module specifically includes: The visual monitoring module obtains an image of the pipette, identifies the scale lines on the pipette through image segmentation, and calculates the pixel distance corresponding to the scale lines in the pixel coordinate system; according to the pipette model information, the volume value represented by each scale line is obtained to realize the correspondence between the pixel coordinates and the physical coordinates, so as to calculate the volume value corresponding to each pixel coordinate; The image of the pipette is sequentially subjected to graying, denoising, smoothing and binarization processing, and the boundary line of the segmentation area is extracted, which is the liquid level line; Obtain the position of the liquid level line in the pixel coordinate system, and then calculate the liquid level scale value in the pipette.

Images