A pressure control method and system for a pressure-holding box based on an electric actuator

Abstract

The present invention provides a pressure control method and system for a pressure-holding box based on an electric actuator. Taking the target pressure of the pressure-holding box for pressure holding as the control target, and controlling the proportional relationship between the pressure output, the error, and the integral of the error, as well as the proportional relationship with the rate of change of the error, to achieve precise and rapid control of the electric actuator during the pressure-holding process of the pressure-holding box, eliminate bubbles or overflow glue generated during the pressure-holding process of the pressure-holding box, and improve the system error elimination speed and dynamic response ability.

Description

Technical Field

[0001] The present invention relates to the technical field of equipment automation control, and particularly to a pressure control method and system for a pressure-holding box based on an electric actuator. Background Art

[0002] During the production and assembly of mobile phones and tablets, the TP touch screen is connected to the outer frame by an adhesive method; after the TP touch screen and the outer frame are bonded, a pressure-holding box is required to apply pressure to the TP touch screen and the outer frame. This process requires highly precise and stable pressure control to ensure that there are no bubbles and poor bonding phenomena between the screen and other components of the device. Specific requirements include: 1. Uniform pressure application. During the bonding process, the pressure stabilization and holding device ensures that the pressure is evenly distributed over the entire screen surface to prevent bubbles and uneven bonding. 2. Stable pressure. During the entire bonding process, a constant pressure is maintained to avoid bonding defects caused by pressure fluctuations. 3. Precise control. Precise control of the pressure is achieved to meet the requirements of different types of screens and devices.

[0003] The existing actuators for pressure holding of the pressure-holding box are mainly pneumatic or hydraulic actuators. With the wear of the equipment or the leakage of seals and connection parts in the device, the pressure holding and stabilization effects are affected; moreover, when pressure fluctuations occur inside or outside the system and need to be adjusted in a timely manner, the response speed of pneumatic or hydraulic actuators is slow and the response cycle is long.

[0004] Due to its advantages such as precise control, fast response, high energy efficiency, easy integration and maintenance, the electric actuator has become an indispensable important component in modern industrial automation systems. The electric actuator can provide precise position, speed and force control and is suitable for application scenarios that require high-precision control. By designing appropriate control logic, the realization of complex control movement lines can be achieved, and it can quickly respond to execution control instructions to meet dynamic control requirements.

[0005] Facing the large-scale batch processing requirements of the pressure-holding box, to ensure the stable quality of the product, a control method and system based on an electric actuator are needed, which can automatically identify whether bubbles or glue overflow occur through the pressure data of the sensor and the image data after pressure holding, generate feedback control data for the electric actuator, adjust the pressure, and determine the execution action control of the electric actuator. Summary of the Invention

[0006] To solve the problems raised in the above background art, the present invention provides a pressure control method and system for a pressure-holding box based on an electric actuator, taking the pressure requirement for pressure holding of the pressure-holding box as the control target, controlling the proportional relationship between the pressure output, the error and the integral of the error, as well as the proportional relationship with the rate of change of the error, to achieve precise and rapid control of the electric actuator during the pressure holding process of the pressure-holding box, eliminate bubbles or overflow glue generated during the pressure holding process of the pressure-holding box, and improve the system error elimination speed and dynamic response ability.

[0007] To achieve the above object, in the first aspect of the present invention, a pressure control method for a pressure-holding box based on an electric actuator is provided, including:

[0008] S1, set the target pressure value P of the pressure-holding box according to the process requirements obj , and set the control parameters of the electric actuator according to the target pressure value P of the pressure-holding box obj . The control parameters of the electric actuator include: proportional control coefficient K p , integral control coefficient K i and derivative control coefficient K d ;

[0009] S2, determine that the time interval for the high-precision pressure sensor to collect the real-time pressure value in the pressure-holding box is Δt, and collect the real-time pressure value P in the pressure-holding box rt ;

[0010] S3, calculate the adjustment parameter f(t) at time t of the pressure-holding box according to the difference between the target pressure value P of the pressure-holding box obj and the real-time pressure value P in the pressure-holding box rt ;

[0011] S4, calculate the control output proportional term P(t) at time t of the pressure-holding box;

[0012] S5, calculate the control output integral term I(t) at time t of the pressure-holding box;

[0013] S6, calculate the control output derivative term D(t) at time t of the pressure-holding box;

[0014] S7, calculate the output control signal C(t) according to the control output proportional term P(t), the control output integral term I(t) and the control output derivative term D(t);

[0015] S8, calculate the output y(t) of the electric actuator;

[0016] S9, collect images;

[0017] S10, perform grayscale processing on the images;

[0018] S11, perform filtering and denoising processing on the images;

[0019] S12. Perform boundary detection on the image;

[0020] S13. Extract features from the image;

[0021] S14. Perform threshold determination on the image;

[0022] S15. Increase the target pressure value P of the pressure - maintaining box obj ;

[0023] S16. Decrease the target pressure value P of the pressure - maintaining box obj .

[0024] As a further description of the above - mentioned technical solution: The step S2 includes:

[0025] Step S201: The real - time pressure value in the pressure - maintaining box is obtained by jointly collecting multiple pressure sensors. The number of pressure sensors is set to n. Then where, is the real - time pressure value in the pressure - maintaining box collected by the i - th pressure sensor;

[0026] Step S202. Calculate the mean value μ of the real - time pressure values in the pressure - maintaining box collected by n pressure sensors through the following formula: where, is the real - time pressure value in the pressure - maintaining box collected by the i - th pressure sensor;

[0027] Step S203. Calculate the standard deviation σ of the real - time pressure values in the pressure - maintaining box collected by n pressure sensors through the following formula:

[0028] Step S204. Set the out - of - tolerance threshold of the real - time pressure value in the pressure - maintaining box as Let where ∨ is the OR condition;

[0029] Step S205. Individually perform out - of - tolerance determination on the real - time pressure values in the pressure - maintaining box collected by the pressure sensors;

[0030] Step S206. If then it indicates that the real - time pressure value is out of tolerance, and delete the real - time pressure value in the pressure - maintaining box collected by this pressure sensor

[0031] Step S207. Obtain the real - time pressure values in the pressure - maintaining box collected by m pressure sensors whose pressure values are not out of tolerance. Then where m ≤ n.

[0032] As a further description of the above - mentioned technical solution: The step S4 includes: Step S401. Calculate the control output proportional term P(t) of the pressure - maintaining box at time t according to the following formula:

[0033] P(t) = K p ×f(t);

[0034] Step S5 includes: Step S501, calculating the integral term I(t) of the control output of the pressure-holding box at time t according to the following formula:

[0035] I(t) = I(t - 1) + K i ×f(t)×Δt;

[0036] Step S6 includes:

[0037] Step S601, calculating the derivative term D(t) of the control output of the pressure-holding box at time t according to the following formula:

[0038]

[0039] Step S7 includes: Step S701, calculating the output control signal C(t) according to the following formula:

[0040]

[0041] where I(t - 1) is the integral term of the control output at time t - 1, and f(t - 1) is the adjustment parameter at time t - 1.

[0042] As a further description of the above technical solution: Step S8 includes:

[0043] Step S801, calculating the output y(t) of the electric actuator according to the input system gain K and time constant τ in the technical parameters of the electric actuator itself using the following formula:

[0044]

[0045] where K is the input system gain of the electric actuator,

[0046] τ is the time constant,

[0047] is a constant related to τ and the time interval Δt,

[0048] C(t) is the output control signal of the electric actuator,

[0049] y(t - 1) is the output of the electric actuator at time t - 1.

[0050] As a further description of the above technical solution: Step S9 includes:

[0051] Step S901: Use a high-resolution camera to capture the processed screen of the pressure-holding box, obtaining a digital image I(x,y) = CIAC(x,y), where CIAC(x,y) is the image directly captured by the high-resolution camera, and I(x,y) is the color image pixel value at (x,y), which is calculated by the following formula:

[0052] I(x,y) = [I r (x,y), I g (x,y), I b (x,y)],

[0053] where I r (x,y) is the intensity value of the red channel at position (x,y), I g (x,y) is the intensity value of the green channel at position (x,y), I b (x,y) is the intensity value of the blue channel at position (x,y), x is the abscissa of the image, and y is the ordinate of the image.

[0054] As a further description of the above technical solution: The said step S10 includes:

[0055] Step S1001: Grayscale the intensity values of the (x,y) three-color channels through the following formula:

[0056] I rg (x,y) = 0.2989 × I r (x,y) + 0.5870 × I g (x,y) + 0.1140 × I b (x,y),

[0057] where I rg (x,y) is the intensity value of the grayscale image at position (x,y);

[0058] The said step S11 includes:

[0059] Step S1101: Perform filtering and denoising processing according to the following formula:

[0060]

[0061] where G f (x,y) is the image intensity value after Gaussian filter denoising, σ is the standard deviation of the Gaussian distribution, and * is the convolution operation on the image;

[0062] The said step S12 includes:

[0063] Step S1201: Use the Canny edge detection algorithm to perform edge detection on the filtered and denoised image to obtain the edge detection map E(x,y) of the image, where E(x,y) = Canny(G f (x,y));

[0064] The above-mentioned step S13 includes:

[0065] Step S1301: Use the findCoutours contour detection algorithm in Opencv to extract the contours of the image edge detection map E(x,y);

[0066] Step S1302: Calculate the area A of each contour i : A i = contourArea(Contour i );

[0067] Step S1303: Calculate the perimeter P of each contour i : P i = arcLength(Contour i , True);

[0068] Step S1304: Calculate the shape factor S of each contour i ,

[0069] As a further description of the above technical solution: The above-mentioned step S14 includes:

[0070] Step S1401: Set the judgment area threshold as the perimeter threshold as and the shape factor threshold as

[0071] Step S1402: If where ∧ is the AND condition, it is determined that bubbles are generated, and go to step S15;

[0072] Step S1403: If it is determined that glue overflow occurs, and go to step S16;

[0073] Step S1404: Otherwise, keep the target pressure value P of the pressure-holding box obj .

[0074] As a further description of the above technical solution: The above-mentioned step S15 includes:

[0075] Step S1501: Let P obj = (1 + 0.05) × P obj , and return to step S2.

[0076] As a further description of the above technical solution: step S16 includes:

[0077] Step S1601, let P obj =(1 - 0.05)×P obj , and return to step S2.

[0078] In the second aspect of the present invention, a pressure control system for a pressure-holding box based on an electric actuator is provided, and the pressure-holding box is pressure-controlled by using a pressure control method for a pressure-holding box based on an electric actuator as described above.

[0079] Compared with the prior art, a pressure control method and system for a pressure-holding box based on an electric actuator provided by the present invention take the target pressure for pressure-holding of the pressure-holding box as the control target, and control the proportional relationship between the pressure output and the error and the integral of the error, as well as the proportional relationship with the error change rate, so as to achieve precise and rapid control of the electric actuator during the pressure-holding process of the pressure-holding box, eliminate bubbles or overflow glue generated during the pressure-holding process of the pressure-holding box, and improve the system error elimination speed and dynamic response ability. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for describing the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can also obtain other drawings based on these drawings without creative efforts.

[0081] Figure 1 is a flowchart of a pressure control method for a pressure-holding box based on an electric actuator proposed by the present invention;

[0082] Figure 2 is a schematic structural diagram of a pressure control system for a pressure-holding box based on an electric actuator proposed by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0083] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0084] Please refer to Figure 1 , in the first aspect of the present invention, a pressure control method for a pressure-holding box based on an electric actuator is provided, including:

[0085] S1, set the target pressure value P of the pressure-holding box according to the process requirementsobj , and set the control parameters of the electric actuator according to the target pressure value P of the pressure-holding box obj .

[0086] Optionally, the control parameters of the electric actuator include: proportional control coefficient K p , integral control coefficient K i and derivative control coefficient K d etc.

[0087] S2. Determine that the time interval for the high-precision pressure sensor to collect the real-time pressure value in the pressure-holding box is Δt, and the real-time pressure value in the pressure-holding box collected is P rt .

[0088] Optionally, this step further includes:

[0089] Step S201: The real-time pressure value in the pressure-holding box is jointly collected by multiple pressure sensors. The number of pressure sensors is set to n. Then, the real-time pressure value P in the pressure-holding box is calculated by the following formula rt :

[0090]

[0091] where is the real-time pressure value in the pressure-holding box collected by the i-th pressure sensor;

[0092] Step S202. Calculate the mean value μ of the real-time pressure value in the pressure-holding box collected by n pressure sensors by the following formula:

[0093]

[0094] Step S203. Calculate the standard deviation σ of the real-time pressure value in the pressure-holding box collected by n pressure sensors by the following formula:

[0095] Step S204. Set the out-of-tolerance threshold of the real-time pressure value in the pressure-holding box as Let where ∨ is the OR condition;

[0096] Step S205. Judge the out-of-tolerance of the real-time pressure value in the pressure-holding box collected by each pressure sensor one by one;

[0097] Step S206. If it means that the real-time pressure value is out of tolerance, then delete the real-time pressure value in the pressure-holding box collected by this pressure sensor

[0098] Step S207. Obtain the real-time pressure value in the pressure-holding box collected by m pressure sensors whose real-time pressure value is not out of tolerance, then where m ≤ n.

[0099] S3. Calculate the adjustment parameter f(t) at time t of the pressure-holding box according to the difference between the target pressure value P of the pressure-holding box obj and the real-time pressure value P rt inside the pressure-holding box, that is: f(t) = P obj - P rt .

[0100] S4. Calculate the proportional term P(t) of the control output at time t of the pressure-holding box.

[0101] Optionally, this step further includes:

[0102] Step S401. Calculate the proportional term P(t) of the control output at time t of the pressure-holding box according to the following formula:

[0103] P(t) = K p × f(t);

[0104] S5. Calculate the integral term I(t) of the control output at time t of the pressure-holding box.

[0105] Optionally, this step further includes:

[0106] Step S501. Calculate the integral term I(t) of the control output at time t of the pressure-holding box according to the following formula:

[0107] I(t) = I(t - 1)+ K i × f(t)× Δt;

[0108] S6. Calculate the derivative term D(t) of the control output at time t of the pressure-holding box.

[0109] Optionally, this step further includes:

[0110] Step S601. Calculate the derivative term D(t) of the control output at time t according to the following formula:

[0111]

[0112] S7. Calculate the output control signal C(t) according to the proportional term P(t), integral term I(t) and derivative term D(t) of the control output.

[0113] Optionally, this step further includes:

[0114] Step S701. Calculate the output control signal C(t) according to the following formula:

[0115]

[0116] Among them, I(t - 1) is the integral term of the control output at time t - 1, and f(t - 1) is the adjustment parameter at time t - 1.

[0117] S8. Calculate the output y(t) of the electric actuator.

[0118] Optionally, this step further includes:

[0119] Step S801. According to the input system gain K and time constant τ in the technical parameters of the electric actuator itself, use the following formula to calculate the output y(t) of the electric actuator:

[0120]

[0121] Among them, K is the input system gain of the electric actuator, τ is the time constant, is a constant related to τ and time interval Δt, C(t) is the output control signal of the electric actuator, and y(t - 1) is the output of the electric actuator at time t - 1.

[0122] Optionally, the output of the electric actuator can be current, torque, displacement, pressure, etc., which is determined by the model of the electric actuator.

[0123] S9. Collect images.

[0124] Optionally, this step further includes:

[0125] Step S901. Use a high - resolution camera to take pictures of the screen after the pressure - holding box is processed to obtain a digital image I(x, y) = CIAC(x, y), where CIAC(x, y) is the image directly collected by the high - resolution camera, and I(x, y) is the color image pixel value at (x, y) of the color image, which is calculated by the following formula:

[0126] I(x, y) = [I r (x, y), I g (x, y), I b (x, y)],

[0127] Among them, I r (x, y) is the intensity value of the red channel at position (x, y), I g (x, y) is the intensity value of the green channel at position (x, y), I b (x, y) is the intensity value of the blue channel at position (x, y), x is the abscissa of the image, and y is the ordinate of the image.

[0128] S10. Perform grayscale processing on the image.

[0129] Optionally, this step further includes:

[0130] Step S1001, grayscale the (x,y) three-color channel intensity values through the following formula:

[0131] I rg (x,y) = 0.2989 × I r (x,y) + 0.5870 × I g (x,y) + 0.1140 × I b (x,y),

[0132] where, I rg (x,y) is the intensity value of the grayscale image at the position (x,y).

[0133] S11, perform filtering and denoising on the image;

[0134] Optionally, this step further includes:

[0135] Step S1101, perform filtering and denoising according to the following formula:

[0136]

[0137] where, G f (x,y) is the image intensity value after denoising by the Gaussian filter, σ is the standard deviation of the Gaussian distribution, and * is the convolution operation on the image.

[0138] S12, perform boundary detection on the image;

[0139] Optionally, this step further includes:

[0140] Step S1201, use the Canny edge detection algorithm to perform edge detection on the filtered and denoised image, and obtain the edge detection map E(x,y) of the image, E(x,y) = Canny(G f (x,y)).

[0141] Optionally, if it is necessary to accelerate the voltage regulation response speed, the proportional control coefficient K p can be increased. If it is necessary to suppress system oscillation, the proportional control coefficient K p can be decreased.

[0142] Optionally, if it is necessary to eliminate the steady-state error, the integral control coefficient K i can be increased. If it is necessary to accelerate the voltage regulation response speed, the integral control coefficient K i can be decreased.

[0143] Optionally, if it is necessary to improve system stability and reduce overshoot, the derivative control coefficient K d can be increased. If it is necessary to suppress system noise sensitivity, the derivative control coefficient K d can be decreased.

[0144] Step S1203,

[0145] S13, extract features from the image;

[0146] Optionally, this step further includes:

[0147] Step S1301, use the findCoutours contour detection algorithm in Opencv to extract the contours of the image edge detection map E(x,y);

[0148] Step S1302, calculate the area A of each contour i : A i = contourArea(Contour i );

[0149] Step S1303, calculate the perimeter P of each contour i : P i = arcLength(Contour i , True);

[0150] Step S1304, calculate the shape factor S of each contour i ,

[0151] S14, perform threshold determination on the image;

[0152] Optionally, this step further includes:

[0153] Step S1401, set the judgment area threshold to the perimeter threshold to and the shape factor threshold to

[0154] Step S1402, if where ∧ is the AND condition, determine that bubbles are generated, and go to step S15;

[0155] Step S1403, if determine that glue overflow occurs, and go to step S16;

[0156] Step S1404, otherwise, maintain the target pressure value P of the pressure-holding box obj .

[0157] Optionally, if it is detected that the area does not conform to the characteristics of bubbles or glue overflow, it is considered that there are no defects in this area, indicating that the target pressure value P of the pressure-holding box obj is reasonably set, and there is no situation of excessive or too low pressure during the process of controlling the real-time pressure value P in the pressure-holding box rt , then maintain the target pressure value P of the pressure-holding boxobj until the system finishes working.

[0158] S15, increase the target pressure value P of the pressure-holding box obj .

[0159] Optionally, this step further includes:

[0160] Step S1501, if there are bubbles generated, it indicates that the target pressure value P of the pressure-holding box obj is set too low. Let P obj =(1 + 0.05)×P obj , and return to step S2.

[0161] S16, decrease the target pressure value P of the pressure-holding box obj .

[0162] Optionally, this step further includes:

[0163] Step S1601, if there is glue overflow generated, it indicates that the target pressure value P of the pressure-holding box obj is set too high. Let P obj =(1 - 0.05)×P obj , and return to step S2.

[0164] The second aspect of the present invention provides a pressure control system for a pressure-holding box based on an electric actuator, which uses a pressure control method for a pressure-holding box based on an electric actuator as described above to control the pressure of the pressure-holding box.

[0165] Optionally, please refer to Figure 2 , the system includes: a pressure-holding box, an electric actuator, a pressure sensor, a controller, a light source, a high-resolution camera, a motion control system, a data acquisition and processing unit, a data transmission module, and an information processing module.

[0166] Optionally, the electric actuator is arranged at the pressure application point outside the pressure-holding box, the pressure-holding box, the light source, and the high-resolution camera are installed on the motion control system, the pressure sensor and the high-resolution camera are sequentially connected to the data acquisition and processing unit and the information processing module through the data transmission module, and the electric actuator and the motion control system are sequentially connected to the controller and the information processing module through the data transmission module.

[0167] Optionally, the pressure sensor is arranged at the pressure measurement point inside the pressure-holding box for real-time monitoring of the pressure inside the pressure-holding box. The pressure inside the pressure-holding box collected is transmitted to the information processing module through the data acquisition and processing unit. The information processing module generates a control signal according to the pressure data and controls the electric actuator to act through the controller. After receiving the control signal, the actuator can accurately change its output force to adjust the pressure of the pressure-holding box. After the pressure-holding is completed, the information processing module controls the light source, the high-resolution camera, and the pressure-holding box to move to the preset image acquisition position through the motion control system. The information processing module controls the high-resolution camera to collect image data through the data acquisition and processing unit, analyzes whether there are bubbles or glue overflow in the adhesion of the TP touch screen after pressure-holding of the pressure-holding box based on the collected image data, and uses it as the basis for adjusting the target pressure value P of the pressure-holding box. obj basis.

[0168] Preferably, the motion control system is a six-degree-of-freedom robotic arm.

[0169] Preferably, the light source is a shape lamp, a backlight, or a strip lamp.

[0170] Preferably, the controller is a PID controller.

[0171] A pressure control method and system for a pressure-holding box based on an electric actuator provided by the present invention use the target pressure of the pressure-holding box during pressure-holding as the control target, control the proportional relationship between the pressure output and the error and the integral of the error, as well as the proportional relationship with the rate of change of the error, to achieve precise and rapid control of the electric actuator during the pressure-holding process of the pressure-holding box, eliminate bubbles or glue overflow generated during the pressure-holding process of the pressure-holding box, and improve the system error elimination speed and dynamic response ability.

[0172] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

[0173] In the above embodiments, the descriptions of each embodiment have their own emphases. For the parts not detailed or recorded in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0174] Those of ordinary skill in the art can realize that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Professionals can use different methods for each specific application to implement the described functions, but such implementation should not be considered to exceed the scope of the present invention.

[0175] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A pressure control method for a pressure-maintaining box based on an electric actuator, characterized in that: include: S1, set the target pressure value P of the pressure-maintaining box according to the process requirements obj , and according to the target pressure value P of the pressure-maintaining box obj Set the control parameters of the electric actuator, the control parameters of the electric actuator include: proportional control coefficient K p , integral control coefficient K i and differential control coefficient K d ; S2, determine the time interval of the high-precision pressure sensor to collect the real-time pressure value in the pressure-maintaining box as Δt, and collect the real-time pressure value P in the pressure-maintaining box rt ; S3, according to the target pressure value P of the pressure-maintaining box obj And the real-time pressure value P in the pressure box rt The difference is used to calculate the adjustment parameter f(t) of the pressure-maintaining box at time t; S4, calculating the control output proportional term P(t) of the pressure-maintaining box at time t; S5, calculating the control output integral term I(t) of the pressure-maintaining box at time t; S6, calculating the differential term D(t) of the control output of the pressure-maintaining box at time t; S7, calculating an output control signal C(t) according to the control output proportional term P(t), the control output integral term I(t) and the control output differential term D(t); S8, calculating the output y(t) of the electric actuator; S9, collect images; S10, grayscale processing is performed on the image; S11, performing filtering and denoising processing on the image; S12, performing boundary detection on the image; S13, extracting features from the image; S14, performing threshold determination on the image; comprising: step S1401, setting the determination area threshold to The perimeter threshold is and the shape factor threshold is Step S1402, if Where ∧ is and condition, it is determined that bubbles are generated, and the process goes to step S15; step S1403, if If it is determined that there is glue overflow, go to step S16; otherwise, maintain the target pressure value P of the pressure-maintaining box. obj ; S15, increase the target pressure value P of the pressure-maintaining box obj ; S16, lower the target pressure value P of the pressure-maintaining box obj .

2. A pressure control method for a pressure-maintaining box based on an electric actuator according to claim 1, characterized in that: The step S2 comprises: Step S201: The real-time pressure value in the pressure-maintaining box is collected by multiple pressure sensors. The number of pressure sensors is set to n. in, Collect the real-time pressure value in the pressure-maintaining box for the i-th pressure sensor; Step S202, calculating the mean value μ of the real-time pressure values ​​in the pressure-maintaining box collected by n pressure sensors by the following formula: in, is the real-time pressure value in the pressure-maintaining box collected by the i-th pressure sensor; Step S203, calculating the standard deviation σ of the real-time pressure values ​​in the pressure-maintaining box collected by n pressure sensors by the following formula: Step S204, setting the threshold of the real-time pressure value in the pressure-maintaining box to make Where ∨ is the OR condition; Step S205, performing out-of-tolerance determination on the real-time pressure values ​​in the pressure-maintaining box collected by the pressure sensor one by one; Step S206, if This means that the real-time pressure value is out of tolerance, and the real-time pressure value in the pressure box collected by the pressure sensor is deleted. Step S207, obtain m pressure sensors with pressure values ​​within tolerance to collect real-time pressure values ​​in the pressure-maintaining box, then Among them, m≤n.

3. A pressure control method for a pressure-maintaining box based on an electric actuator according to claim 1, characterized in that: The step S4 includes: step S401, calculating the proportional term P(t) of the pressure-maintaining box control output at time t according to the following formula: P(t)=K p ×f(t); calculate the adjustment parameter f(t) of the pressure box at time t, that is: f(t) = P obj -P rt , the step S5 comprises: step S501, calculating the control output integral term I(t) of the pressure-maintaining box at time t according to the following formula: I(t)=I(t-1)+K i ×f(t)×Δt; The step S6 comprises: Step S601, calculate the control output differential term D(t) of the pressure-maintaining box at time t according to the following formula: The step S7 comprises: step S701, calculating the output control signal C(t) according to the following formula: Among them, I(t-1) is the integral term of the control output at time t-1, and f(t-1) is the adjustment parameter at time t-1.

4. A pressure control method for a pressure-maintaining box based on an electric actuator according to claim 1, characterized in that: The step S8 comprises: Step S801, according to the input system gain K and time constant τ in the technical parameters of the electric actuator itself, the electric actuator output y(t) is calculated using the following formula: Where K is the electric actuator input system gain, τ is the time constant, is a constant related to τ and the time interval Δt, C(t) is the output control signal of the electric actuator, y(t-1) is the output of the electric actuator at time t-1.

5. The pressure control method of a pressure-maintaining box based on an electric actuator according to claim 1, characterized in that: The step S9 comprises: Step S901, use a high-resolution camera to shoot the screen after the pressure-maintaining box treatment, and obtain a digital image I(x, y) = CIAC(x, y), where CIAC(x, y) is the image directly captured by the high-resolution camera, and I(x, y) is the color image pixel value at (x, y), which is calculated by the following formula: I(x,y)=[I r (x,y),I g (x,y),I b (x,y)], Among them, I r (x,y) is the intensity value of the red channel at position (x,y), I g (x,y) is the intensity value of the green channel at position (x,y), I b (x,y) is the intensity value of the blue channel at position (x,y), x is the horizontal coordinate of the image, and y is the vertical coordinate of the image.

6. A pressure control system for a pressure-maintaining box based on an electric actuator according to claim 5, characterized in that: The step S10 comprises: Step S1001, grayscale the (x, y) three-color channel intensity values ​​using the following formula: Yo rg (x,y)=0.2989×I r (x,y)+0.5870×I g (x,y)+0.1140×I b (x,y), Among them, I rg (x,y) is the intensity value of the grayscale image at position (x,y); The step S11 comprises: Step S1101, filtering and denoising are performed according to the following formula: Among them, G f (x, y) is the image intensity value after Gaussian filter denoising, σ is the standard deviation of Gaussian distribution, and * is the convolution operation on the image; The step S12 comprises: Step S1201, use the Canny edge detection algorithm to perform edge detection on the filtered and denoised image to obtain an edge detection graph E(x, y) of the image, where E(x, y) = Canny(G f (x,y)); The step S13 comprises: Step S1301, using the findCoutours contour detection algorithm of Opencv to extract the contour of the image edge detection graph E(x,y); Step S1302: Calculate the area A of each contour i : A i =contourArea(Contour i ); Step S1303: Calculate the perimeter P of each contour i :P i =arcLength(Contour i ,True); Step S1304: Calculate and obtain the shape factor S of each contour i , 7. The pressure control system for a pressure-maintaining box based on an electric actuator according to claim 1, characterized in that: The step S15 comprises: Step S1501: Set P obj =(1+0.05)×P obj , return to step S2.

8. The pressure control system for a pressure-maintaining box based on an electric actuator according to claim 1, characterized in that: The step S16 comprises: Step S1601, let P obj =(1-0.05)×P obj , return to step S2.

9. A pressure control system for a pressure-maintaining box based on an electric actuator, which controls the pressure of the pressure-maintaining box by using a pressure control method for a pressure-maintaining box based on an electric actuator as described in any one of claims 1 to 8.

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