A method for decoupling control of hot air speed of a cut tobacco dryer and moisture removal negative pressure, and a storage medium

Abstract

The application discloses a kind of decoupling control methods of hot air velocity and moisture exhaust negative pressure of cut tobacco dryer, storage medium, comprising: when cut tobacco dryer enters preheating or production stage mode, according to the control variable output in hot air velocity control loop and moisture exhaust negative pressure control loop under single closed loop negative feedback PID control, judge whether hot air velocity control loop and moisture exhaust negative pressure control loop enter preset linearization area;When hot air velocity control loop and moisture exhaust negative pressure control loop enter preset linearization area, the static gain matrix of cut tobacco dryer control system is obtained using process identification method, and the relative gain matrix is obtained by matrix transformation;When relative gain matrix meets preset constraint condition, hot air velocity control loop and moisture exhaust negative pressure control loop are decoupled controlled using feedforward decoupling controller.The application can improve the control performance of cut tobacco dryer control system, realize more accurate, more stable control purpose.

Description

Technical Field

[0001] This invention relates to a decoupling control method and storage medium for hot air velocity and dehumidification negative pressure in a wire drying machine, belonging to the field of wire drying machine control technology. Background Technology

[0002] The common working principle of cigarette drying machines is as follows: a certain flow rate of steam passes through the inner wall of the thin plate of the drum. The steam condenses in the steam channel, effectively transferring heat to the tobacco shreds on the plate. Simultaneously, a fan sends ambient air into a steam-heated heat exchanger to generate hot air. As the hot air flows through the drum, the temperature and velocity of the hot air are controlled, creating convection to transfer heat to the tobacco shreds and remove moisture. This ensures uniform drying, uniform heating, and a uniform increase in filling force, as well as a constant outlet moisture content. An internal dehumidification negative pressure system is installed inside the drum to extract and discharge some of the water-containing and hot exhaust gas, thus maintaining a constant moisture content in the material and indirectly affecting its moisture content. Therefore, the hot air velocity and dehumidification negative pressure are crucial control loops within the drying machine, and their control performance directly impacts product quality.

[0003] Existing yarn drying machines are nonlinear systems, and the industry commonly uses PID loops for control. The hot air temperature control method uses sampled hot air velocity values ​​as feedback data to control the hot air damper actuator in a single-loop control. Simultaneously, the dehumidification negative pressure control method uses sampled negative pressure values ​​as feedback data to adjust the negative pressure damper actuator in a single-loop control. Because the hot air damper actuator's operation affects the airflow changes inside the drying machine, deviations in the negative pressure value will cause the damper actuator to adjust, resulting in fluctuations in negative pressure control. Furthermore, the operation of the negative pressure damper actuator will cause gas pressure fluctuations within the cylinder, leading to small fluctuations in the hot air velocity. For the reasons mentioned above, although the existing hot air speed and dehumidification negative pressure control of the silk making and drying machine adopts single-loop PID control, there is a certain nonlinear system coupling relationship between the two. When one loop fluctuates and enters the adjustment, it will inevitably affect the other loop to some extent, thereby affecting the control performance of hot air speed and dehumidification negative pressure. In order to achieve the goal of accurate and stable control, it is necessary to consider the decoupling problem on the basis of linearization. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a decoupled control method and storage medium for the hot air velocity and dehumidification negative pressure of a yarn drying machine. By linearizing the nonlinear system of the yarn drying machine, and simultaneously providing decoupled control of the hot air velocity and dehumidification negative pressure, the invention aims to improve the control performance of the hot air velocity and dehumidification negative pressure, thereby enhancing the stability, convergence, and robustness of the system.

[0005] To solve the above-mentioned technical problems, the present invention is implemented using the following technical solution.

[0006] In a first aspect, the present invention provides a decoupling control method for hot air velocity and dehumidification negative pressure in a yarn drying machine, comprising the following steps:

[0007] When the drying machine enters the preheating or production stage mode, based on the control variables output by the hot air speed control loop and the dehumidification negative pressure control loop under the single closed-loop negative feedback PID control, it is determined whether the hot air speed control loop and the dehumidification negative pressure control loop have entered the preset linearization region.

[0008] When the hot air speed control loop and the dehumidification negative pressure control loop enter the preset linearization region, the static gain matrix of the wire drying machine control system is obtained by the process identification method, and the relative gain matrix is ​​obtained by matrix transformation.

[0009] When the relative gain matrix meets the preset constraints, the feedforward decoupling controller is used to decouple the hot air velocity control loop and the dehumidification negative pressure control loop.

[0010] Furthermore, the control variables output by the hot air speed control loop and the dehumidification negative pressure control loop include hot air speed u1, hot air damper opening y1, dehumidification negative pressure u2, and negative pressure damper opening y2.

[0011] Furthermore, the determination of whether the hot air velocity control loop and the dehumidification negative pressure control loop have entered the preset linearization region includes:

[0012] When the control variables output by the hot air speed control loop and the dehumidification negative pressure control loop fall within the area enclosed by the preset four-dimensional space Γ(x,y,z,r), and the system is stable and the data does not change abruptly, it is considered that the hot air speed control loop and the dehumidification negative pressure control loop have entered the linearization region.

[0013] Furthermore, the region enclosed by the four-dimensional space Γ(x,y,z,r) is:

[0014]

[0015] Where x, y, z, and r are the four dimensions of the four-dimensional space Γ(x,y,z,r), SP1 is the hot air velocity setting value, ΔSP1 is the preset hot air velocity change threshold, SP2 is the dehumidification negative pressure setting value, ΔSP2 is the preset dehumidification negative pressure change threshold, CV1(∞) is the steady-state value of the hot air damper opening output by the hot air velocity control loop, ΔCV1 is the preset hot air damper opening change threshold, CV2(∞) is the steady-state value of the negative pressure damper opening output by the dehumidification negative pressure control loop, and ΔCV2 is the preset negative pressure damper opening change threshold.

[0016] Furthermore, let the coordinates of the two sets of control variables obtained before and after a sampling unit time in four-dimensional space be Γ1=(x1,y1,z1,r1) and Γ2=(x2,y2,z2,r2), respectively. The Euclidean distance is calculated using the norm based on the four-dimensional coordinates.

[0017]

[0018] Where ||Dis|| is the Euclidean distance between coordinate point Γ2 and coordinate point Γ1 in four-dimensional space;

[0019] When ||Dis||≤D, the system is considered stable and the data does not undergo sudden changes.

[0020] Furthermore, the static gain matrix of the wire drying machine control system is obtained using the process identification method, and the relative gain matrix is ​​obtained through matrix transformation, including:

[0021] The transfer function between the control variables under PID control is obtained using the process identification method, where:

[0022] The transfer function W from hot air velocity to hot air damper opening 11 The expression for (s) is:

[0023]

[0024] Where s is the Laplace transform operator, K 11 T is the static gain from hot air velocity to hot air damper opening. 111 T is the first inertial time parameter from hot air velocity to hot air damper opening. 112 τ11 is the second inertial time parameter from hot air velocity to hot air damper opening, and τ11 is the lag time parameter from hot air velocity to hot air damper opening.

[0025] The transfer function W of the opening degree of the dehumidification negative pressure damper to the negative pressure damper. 22 The expression for (s) is:

[0026]

[0027] Among them, K 22 T is the static gain of the damper opening from negative pressure to negative pressure. 221 T is the first inertial time parameter from the negative pressure of the exhaust damper to the opening of the negative pressure damper. 222 τ22 is the second inertial time parameter from the negative pressure of the exhaust to the opening of the negative pressure damper, and τ22 is the lag time parameter from the negative pressure of the exhaust to the opening of the negative pressure damper.

[0028] The transfer function W from hot air velocity to negative pressure damper opening 21 The expression for (s) is:

[0029]

[0030] Among them, K 21 T is the static gain from hot air velocity to negative pressure damper opening. 21 τ21 is the inertial time parameter from hot air velocity to negative pressure damper opening, and τ22 is the lag time parameter from hot air velocity to negative pressure damper opening.

[0031] The transfer function W from the opening of the hot air damper to the negative pressure of the exhaust system 12 The expression for (s) is:

[0032]

[0033] Among them, K 12 T is the static gain from the opening of the hot air damper to the negative pressure of the exhaust. 12 τ12 is the inertial time parameter from the opening of the hot air damper to the negative pressure of the exhaust, and τ12 is the lag time parameter from the opening of the hot air damper to the negative pressure of the exhaust.

[0034] The static gain matrix K of the wire drying machine control system is obtained based on the transfer function between the control variables under PID control:

[0035]

[0036] Based on the static gain matrix, the relative gain matrix λ is calculated through matrix transformation:

[0037]

[0038] Where, λ 11 λ represents the relative gain from hot air velocity to hot air damper opening. 12 λ is the relative gain from the opening of the hot air damper to the negative pressure of the exhaust. 21 λ represents the relative gain from hot air velocity to negative pressure damper opening. 22 H represents the relative gain of the damper opening from negative pressure to negative pressure, and H is the inverse of the static gain matrix K.

[0039] Furthermore, the constraints on the relative gain matrix include:

[0040]

[0041]

[0042] Furthermore, the feedforward decoupling controller includes a transfer function W for decoupling compensation of the influence of the exhaust negative pressure control on the hot air velocity. D21 (s) and the transfer function W used to decouple and compensate for the negative pressure affecting the hot air velocity control. D12 (s);

[0043] According to the principle of invariance, setting the disturbance to 0, we get:

[0044]

[0045]

[0046] Among them, W 11 (s) is the transfer function from hot air velocity to hot air damper opening under PID control, W 22 (s) is the transfer function of the opening degree of the negative pressure damper from the exhaust negative pressure to the negative pressure damper under PID control, W 21 (s) is the transfer function from hot air velocity to negative pressure damper opening under PID control, W 12 (s) is the transfer function from the opening of the hot air damper to the negative pressure of dehumidification under PID control.

[0047] Furthermore, when W D12 (s) and W D21 (s) simplifies to:

[0048]

[0049]

[0050] Among them, K 12 T is the static gain from the opening of the hot air damper to the negative pressure of the exhaust. 111 T is the first inertial time parameter from hot air velocity to hot air damper opening. 112 Let be the second inertial time parameter from hot air velocity to hot air damper opening, s be the Laplace transform operator, and K be the second inertial time parameter. 11 T is the static gain from hot air velocity to hot air damper opening. 12 K is the inertial time parameter from the opening of the hot air damper to the negative pressure of the dehumidification. 21 T is the static gain from hot air velocity to negative pressure damper opening. 221 T is the first inertial time parameter from the negative pressure of the exhaust damper to the opening of the negative pressure damper. 222 K is the second inertial time parameter for the change from negative pressure to negative pressure damper opening. 22 T is the static gain of the damper opening from negative pressure to negative pressure. 21 This is the inertial time parameter from hot air velocity to negative pressure damper opening.

[0051] In a second aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the decoupling control method for hot air velocity and dehumidification negative pressure of a drying machine in the first aspect.

[0052] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0053] This invention proposes a decoupled control method and storage medium for hot air velocity and dehumidification negative pressure in a yarn drying machine. By identifying the linearization state from the nonlinear yarn drying machine control system through a preset linearization region, a feedforward decoupling controller is used to decouple the hot air velocity and dehumidification negative pressure under the linearization state. This eliminates the mutual influence between the wind speed control and negative pressure control under the existing PID control, thereby improving the control performance of the yarn drying machine control system and achieving more accurate and stable control.

[0054] This invention calculates the relative gain matrix by matrix transformation of the static gain matrix of multiple channels, and verifies whether the value of the relative gain matrix conforms to common sense based on mechanistic experience, thus providing data-driven mechanistic verification of the stability, convergence and robustness of decoupling control.

[0055] The feedforward decoupling controller of this invention eliminates coupling through feedforward compensation, and removes coupling disturbances by designing a compensator-type feedforward path feedback, ensuring the reliability and accuracy of decoupling. Simultaneously, this invention simplifies the decoupling process, ensuring the stability, convergence, and robustness of the decoupling control. Attached Figure Description

[0056] Figure 1 The diagram shows the steps of the decoupling control method for hot air velocity and dehumidification negative pressure in the filament drying machine of the present invention.

[0057] Figure 2 The diagram shown is a schematic of the hot air speed control loop and the dehumidification negative pressure control loop under PID control in an embodiment of the present invention.

[0058] Figure 3 The diagram shown illustrates the steps for calculating the relative gain matrix in an embodiment of the present invention.

[0059] Figure 4 The diagram shown is a schematic of the feedforward decoupling controller after linearization processing in an embodiment of the present invention;

[0060] Figure 5 The diagram shown illustrates a scenario where nonlinear characteristics are manifested without feedforward decoupling control in an embodiment of the present invention. Detailed Implementation

[0061] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical solution of the present invention, rather than limitations thereof. In the absence of conflict, the embodiments of the present invention and the technical features in the embodiments can be combined with each other.

[0062] Example 1

[0063] This embodiment introduces a decoupled control method for hot air velocity and dehumidification negative pressure in a yarn drying machine, such as... Figure 1 As shown, the specific steps include the following:

[0064] Step A: Obtain the working signal of the wire drying machine. Based on the working signal, determine whether the wire drying machine has started preheating or production. When the wire drying machine enters the preheating or production stage mode, use a single closed-loop negative feedback PID to control the opening ratio of the hot air damper actuator in the corresponding hot air velocity circuit of the wire drying machine, and use a single closed-loop negative feedback PID to control the opening ratio of the negative pressure damper actuator in the dehumidification negative pressure control circuit.

[0065] In this embodiment of the invention, the hot air speed control circuit and the dehumidification negative pressure control circuit both belong to the yarn drying machine control system, such as... Figure 2 As shown, it is assumed that the wind speed damper control in the hot air wind speed control loop is a PID loop #1 and the dehumidification negative pressure control is a PID loop #2. Both of them first adopt uncoupled single-input single-output closed-loop PID control.

[0066] This invention mainly decouples the normal production process of the wire drying machine. Other stages, such as preheating, standby, and residual material output, are controlled according to the original equipment control methods and are not within the scope of this invention.

[0067] Step B: Based on the control variables output by the hot air speed control loop and the dehumidification negative pressure control loop under closed-loop PID control, determine whether the hot air speed control loop and the dehumidification negative pressure control loop have entered the preset linearization region. If the PID of the two auxiliary loops meets the linearization processing conditions, it is considered that the nonlinear control system of the wire drying machine has entered the linear range and meets the decoupling conditions of the linear system, and can proceed to the next step.

[0068] In step B, the method for determining whether the control has entered the linearization region is as follows:

[0069] The control variables output by the hot air speed control loop and the dehumidification negative pressure control loop under closed-loop PID control are obtained. When the control variables output by the two loops fall within the bounded area of ​​the preset four-dimensional space Γ(x,y,z,r), and the system is stable and the data does not change abruptly (the change in the control variable after each sampling unit time is less than the preset threshold D), it is considered that the hot air speed control loop and the dehumidification negative pressure control loop have entered the linearization region, and the wire drying machine control system satisfies the decoupling condition of the linear system.

[0070] In step B, the definition of the four-dimensional space Γ(x,y,z,r) includes:

[0071] (1) Set the steady-state operating point A0, A0 = (u 10 ,u 20 ,y 10 ,y 20), where u 10 u represents the steady-state value of hot air velocity. 20 Indicates the steady-state value of negative pressure during tidal discharge, y 10 y represents the steady-state value of the hot air damper opening. 20 This represents the steady-state value of the negative pressure damper opening.

[0072] (2) Based on the feedback control mechanism of PID, it can be deduced that:

[0073]

[0074]

[0075] Wherein, PV1(∞) is the steady-state value of the actual hot air velocity PV1 measured by the hot air velocity control loop under PID control, which is approximately equal to the hot air velocity setpoint SP1 of the hot air velocity control loop under PID control; PV2(∞) is the steady-state value of the actual dehumidification negative pressure PV2 measured by the dehumidification negative pressure control loop under PID control, which is approximately equal to the dehumidification negative pressure setpoint SP2 of the dehumidification negative pressure control loop under PID control; CV1(∞) is the steady-state value of the hot air damper opening value CV1 output by the hot air velocity control loop under PID control; CV2(∞) is the steady-state value of the negative pressure damper opening value CV2 output by the dehumidification negative pressure control loop under PID control.

[0076] (3) According to formulas (1) and (2), the theoretically approximate steady-state operating point can be represented as a four-dimensional spatial point with coordinates A0 = (SP1, SP2, CV1(∞), CV2(∞)). The area around this point can be considered as a linearized region, which is suitable for coupling analysis and decoupling control.

[0077] This invention extends the linear range with the steady-state operating point A0 as the center and constructs a four-dimensional space Γ(x,y,z,r) to define the linearization region.

[0078] The range of values ​​for the first parameter SP1 of point A0 in the first dimension x of the four-dimensional space Γ(x,y,z,r); the range of values ​​for the second parameter SP2 of point A0 in the second dimension y of the four-dimensional space Γ(x,y,z,r); the range of values ​​for the third parameter CV1(∞) of point A0 in the third dimension z of the four-dimensional space Γ(x,y,z,r); the range of values ​​for the fourth parameter CV2(∞) of point A0 in the fourth dimension r of the four-dimensional space Γ(x,y,z,r); the range of values ​​for the four dimensions of the four-dimensional space Γ(x,y,z,r) are represented as follows:

[0079]

[0080] Among them, ΔSP1, ΔSP2, ΔCV1 and ΔCV2 are the thresholds for the four dimensions of the linearized four-dimensional space, and their specific values ​​are set according to the data collected on-site in the actual application scenario.

[0081] Decoupling control, besides requiring linearization, also needs to ensure system stability and prevent abrupt data changes. Therefore, this invention requires system stability assessment after the system control variables fall into four-dimensional space. In this embodiment, Euclidean distance is used to define the change of the control variables within a sampling unit time.

[0082] The control variables output by the hot air speed control loop and the dehumidification negative pressure control loop under PID control are acquired according to the preset sampling unit time. After the control variables fall into four-dimensional space, they are transformed into four-dimensional coordinates. Let the coordinates of the two sets of control variables acquired before and after one sampling unit time in four-dimensional space be Γ1=(x1,y1,z1,r1) and Γ2=(x2,y2,z2,r2), respectively. The Euclidean distance is calculated using the norm based on the four-dimensional coordinates. The specific formula is as follows:

[0083]

[0084] Where ||Dis|| is the Euclidean distance between coordinate point Γ2 and coordinate point Γ1 in four-dimensional space, which is the change of the control variable in one sampling unit time.

[0085] Based on experiments, this invention sets a distance threshold D. When ||Dis||≤D, the system is considered stable and the data does not undergo sudden changes.

[0086] Step C: Obtain the multi-channel static gain matrix of the linearized system (the drying machine control system that has entered the linearized region and is stable) using the system identification method in process control, and then calculate the relative gain matrix through matrix transformation. Note that the system identification method is existing technology and not within the scope of this invention.

[0087] like Figure 3 As shown, step C specifically includes:

[0088] Step C01: Use the process identification method to obtain the transfer function between each control variable under PID control in the wire drying machine control system.

[0089] Since fluctuations in either the hot air velocity or the negative pressure control loop of the yarn drying machine inevitably affect the other loop to some extent, this invention analyzes the transfer function between the four control variables (u1, u2, y1, y2) in the two loops, as follows:

[0090] C01-1. Based on relevant experience in process control, it can be inferred that the controlled object, hot air speed, in the hot air speed control loop under PID control approaches a self-balancing object with second-order inertia and time lag. Therefore, its transfer function can be expressed as:

[0091]

[0092] Among them, W 11 (s) is the transfer function from hot air velocity to hot air damper opening under PID control, s is the Laplace transform operator, and K 11 T is the static gain from hot air velocity to hot air damper opening under PID control. 111 T is the first inertial time parameter from hot air velocity to hot air damper opening under PID control. 112 τ11 is the second inertial time parameter from hot air velocity to hot air damper opening under PID control, and τ11 is the lag time parameter from hot air velocity to hot air damper opening under PID control.

[0093] Similarly to C01-1, it can be deduced that the controlled object of the tidal negative pressure control loop under PID control approaches a second-order inertial object with time lag, and its transfer function can be expressed as:

[0094]

[0095] Among them, W 22 (s) is the transfer function of the opening degree of the negative pressure damper from the exhaust negative pressure to the negative pressure damper under PID control, K 22 T is the static gain of the tidal discharge negative pressure to negative pressure damper opening under PID control. 221 T is the first inertial time parameter for the change in tidal negative pressure to negative pressure damper opening under PID control. 222 τ22 is the second inertial time parameter from the negative pressure of the tidal discharge to the opening of the negative pressure damper under PID control, and τ22 is the lag time parameter from the negative pressure of the tidal discharge to the opening of the negative pressure damper under PID control.

[0096] C01-3. Based on experience with automatic control principles, it can be deduced that the transfer function from hot air velocity to negative pressure damper opening under PID control approaches first-order inertia plus time lag, and its transfer function can be expressed as:

[0097]

[0098] Among them, W 21 (s) is the transfer function from hot air velocity to negative pressure damper opening under PID control, K 21 T is the static gain of the hot air velocity to the negative pressure damper opening under PID control. 21 τ21 is the inertial time parameter from hot air velocity to negative pressure damper opening under PID control, and τ22 is the lag time parameter from hot air velocity to negative pressure damper opening under PID control.

[0099] Similarly to C01-3, under PID control, the transfer function from the hot air damper opening to the exhaust negative pressure approaches first-order inertia plus time lag, and its transfer function can be expressed as:

[0100]

[0101] Among them, W 12 (s) is the transfer function from the opening of the hot air damper to the negative pressure of dehumidification under PID control, K 12 T is the static gain from the opening of the hot air damper to the negative pressure of the exhaust vent under PID control. 12 τ12 is the inertial time parameter from the opening of the hot air damper to the negative pressure of dehumidification under PID control, and τ12 is the lag time parameter from the opening of the hot air damper to the negative pressure of dehumidification under PID control.

[0102] Step C02: Based on the transfer function in step C01, obtain the static gain matrix K of the wire drying machine control system:

[0103]

[0104] Step C03: Based on the static gain matrix, calculate the relative gain matrix λ through matrix transformation. The calculation formula is as follows:

[0105]

[0106] Where, λ 11 λ represents the relative gain from hot air velocity to hot air damper opening. 12 λ is the relative gain from the opening of the hot air damper to the negative pressure of the exhaust. 21 λ represents the relative gain from hot air velocity to negative pressure damper opening. 22 H represents the relative gain of the damper opening from negative pressure to negative pressure, and H is the inverse of the static gain matrix K.

[0107] Step D: Verify whether the value of the relative gain matrix obtained in step C meets the preset constraints based on the mechanism experience. If it does, proceed to the next step to perform decoupling design. If it does not, reduce the size of the enclosed region of the four-dimensional space Γ(x,y,z,r) and the value of the threshold D, and return to step B until the conditions are met.

[0108] In this embodiment of the invention, the preset constraints include:

[0109]

[0110] Based on the mechanism characteristics of the wire drying machine, there must be a significant coupling relationship between the hot air velocity control loop and the dehumidification negative pressure control loop. Therefore, it can be deduced that the relative gain range is likely as shown in formula (12), and the system needs to perform decoupling correction control. Therefore, the preset constraints also include:

[0111]

[0112] In this embodiment of the invention, if the element λ in the relative gain matrix λ ij If the value is negative, reduce the size of the enclosed region of the four-dimensional space Γ(x,y,z,r) and the value of the threshold D, and return to step B; if λ 11 With λ 22 If the value is close to 1, the system does not need to be decoupled and can continue to be controlled using the original PID control method.

[0113] Step E: When the relative gain matrix satisfies formula (12), a feedforward decoupling controller is used to eliminate the coupling effect between the two loops. When the 1# PID loop for hot air speed control and the 2# PID loop for dehumidification negative pressure control enter the linearization region and stabilize, a feedforward decoupling controller is used for control.

[0114] like Figure 4 As shown, let the transfer function matrix of the wire drying machine control system under PID control be W. O (s), the transfer function matrix of the feedforward decoupling device is W. D (s), the controller transfer function matrix of the filament drying machine control system under PID control is W C (s), the controller output signal of the filament drying machine control system under PID control is U(s), and the output signal of the entire system is Y(s).

[0115] The transfer function matrix W of the filament drying machine control system under PID control O The expression for (s) is:

[0116]

[0117] Among them, W 11 (s) is the process model transfer function for hot air velocity control; W 22 (s) is the process model transfer function for hygroscopic negative pressure control; W 12 (s) is the process model transfer function for the influence of hot air velocity control on negative pressure; W 21 (s) is the process model transfer function that controls the negative pressure of dehumidification and affects the hot air velocity.

[0118] This invention employs the feedforward principle to eliminate coupling. When u1 is paired to control y1, u1 is a disturbance to y2. Therefore, a feedforward device can be designed to address changes in u1, and similarly, u2 is affected by y1. Thus, the method of this invention... 21 (s) and W 12 (s) Treat it as a cross-coupled signal, as interference, and introduce feedforward correction. Figure 4 In the middle, W D11 (s)=W D22 (s) = 1, the transfer function W used for decoupling compensation in the feedforward decoupling controller. D12 (s) and W D21 (s) can be obtained based on the principle of invariance.

[0119] [W D12 (s)W 11 (s)+W 12 [U2(s)] = 0 (14)

[0120] When U(s) is not equal to 0, we can obtain:

[0121]

[0122] Similarly, we have:

[0123] [W D21 (s)W 22 (s)+W 12 [U1(s)] = 0 (16)

[0124]

[0125] Due to W 11 (s), W 22 (s) represents a first-order lag, W 21 (s), W 12 (s) is a second-order hysteresis, which is often difficult to implement when designing feedforward decoupling and may lead to error amplification. Therefore, a decoupling simplification design is required, and the specific operation is as follows:

[0126] (1) Due to W 11 (s), W 22 (s), W 21 (s), W 12 The time constants τ11, τ22, τ21, and τ12 of (s) are all small, so they can be ignored when performing decoupling simplification, that is, let τ11 = τ22 = τ21 = τ12 = 0.

[0127] Then W 21 (s), W 12 The expression for (s) can be simplified to:

[0128]

[0129]

[0130] (2) By observing W 11 (s), W 22 The second-order lag model of (s) reveals that if there exists Then T 111 The characteristics become apparent, almost completely affecting the system characteristics, relative to T. 112 The characteristics of W are negligible and have almost no impact on system performance. 11 (s) can be approximately simplified to:

[0131]

[0132] If it exists Similarly, W 22 (s) can be approximately simplified to:

[0133]

[0134] (3) The simplified W 11 (s), W 22 (s), W 21 (s), W 12 Substituting (s) into formulas (15) and (17), we get:

[0135]

[0136]

[0137] In step E, when the hot air speed control loop and the dehumidification negative pressure control loop of the drying machine enter the linearization region and are in a stable state, the feedforward decoupling controller is used for decoupling control. If the decoupling simplification condition is not met, the transfer function of the feedforward decoupling controller is shown in formula (15) and formula (17). If the decoupling simplification condition is met, the transfer function of the feedforward decoupling controller is shown in formula (22) and formula (23).

[0138] Step F: When the drying machine is in the preheating or production stage, if the hot air speed control loop and the dehumidification negative pressure control loop are in the nonlinear region (not in four-dimensional space) or the linearized unstable state (in the thought space but not satisfying ||Dis||≤D), the system cannot be linearized. The feedforward decoupling controller is cancelled, and the original PID control continues. Alternatively, if the drying machine is in other host states, the nonlinear system cannot be linearized. The feedforward decoupling controller is again cancelled, and the original control is used. Specifically, as follows... Figure 5 As shown.

[0139] Step G: When the production stage of the drying machine ends, shut down the feedforward decoupling controller, end the decoupling control strategy, and make the hot air speed control loop and the dehumidification negative pressure control loop adopt uncoupled single-input single-output closed-loop PID control.

[0140] In this embodiment of the invention, during the on-site test and Matlab simulation at the Hangzhou Cigarette Factory, the effective parameter combination used was: ΔSP1 = 1.0; ΔSP2 = 0.05; ΔCV1 = 10%; ΔCV2 = 10%; sampling unit time Time = 30s; D = 0.054.

[0141] Example 2

[0142] Based on the same inventive concept as Embodiment 1, this embodiment introduces a computer-readable storage medium storing a computer program that, when executed by a processor, implements the decoupling control method for hot air velocity and dehumidification negative pressure of the drying machine described in Embodiment 1.

[0143] This invention eliminates the mutual influence between wind speed control and negative pressure control in the original PID system by decoupling the hot air speed and dehumidification negative pressure of the drying machine. This improves the control performance of the drying machine control system and achieves more precise and stable control.

[0144] This invention defines the linearization region of a dual control loop in a nonlinear system in four-dimensional space. It also introduces Euclidean distance in a formulaic form to determine whether the system is stable and whether the data does not change abruptly. This invention can effectively identify the application scenarios and control prerequisites for using nonlinear systems for linearization approximation, thereby effectively introducing linearization processing and achieving decoupled control.

[0145] This invention calculates the relative gain matrix by matrix transformation of the static gain matrix of multiple channels, and verifies whether the value of the relative gain matrix conforms to common sense based on mechanistic experience, thus providing data-driven mechanistic verification of the stability, convergence and robustness of decoupling control.

[0146] The feedforward decoupling controller designed in this invention eliminates coupling through feedforward compensation, and removes coupling disturbances by designing a forward feedback channel in the form of a compensator, ensuring the reliability and accuracy of decoupling. Furthermore, to ensure the feedforward decoupling system is easy to implement and to prevent the amplification of model-based identification errors, the method of this invention also simplifies the decoupling process, ensuring the stability, convergence, and robustness of the decoupling control.

[0147] The decoupling control designed in this invention is only used in the linearized control region during the production and preheating stages of the wire drying machine. When entering the nonlinear control region of unstable control, the decoupling control is not used, which makes the whole system flexible and relatively stable and convergent, and also has good dynamic characteristics.

[0148] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0149] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0150] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0151] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0152] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A decoupled control method for hot air velocity and dehumidification negative pressure in a yarn drying machine, characterized in that, Includes the following steps: When the drying machine enters the preheating or production stage mode, based on the control variables output by the hot air speed control loop and the dehumidification negative pressure control loop under the single closed-loop negative feedback PID control, it is determined whether the hot air speed control loop and the dehumidification negative pressure control loop have entered the preset linearization region. When the hot air speed control loop and the dehumidification negative pressure control loop enter the preset linearization region, the static gain matrix of the wire drying machine control system is obtained by the process identification method, and the relative gain matrix is ​​obtained by matrix transformation. When the relative gain matrix satisfies the preset constraints, the feedforward decoupling controller is used to decouple the hot air velocity control loop and the dehumidification negative pressure control loop. The determination of whether the hot air velocity control circuit and the dehumidification negative pressure control circuit have entered the preset linearization region includes: When the control variables output by the hot air speed control circuit and the dehumidification negative pressure control circuit fall into the preset four-dimensional space If the system is stable and the data does not change abruptly within the enclosed area, then the hot air velocity control loop and the dehumidification negative pressure control loop are considered to have entered the linearization region. The four-dimensional space The enclosed area is: ； in, For four-dimensional space The four dimensions Set the hot air velocity value. The preset hot air velocity variation threshold. Set as the negative pressure value for moisture removal. The preset threshold for negative pressure change during dehumidification. This represents the steady-state value of the hot air damper opening output by the hot air velocity control loop. This is the preset threshold for the change in the opening of the hot air damper. This refers to the steady-state value of the negative pressure damper opening output by the negative pressure control circuit for dehumidification. This is the preset threshold for the change in the opening of the negative pressure damper.

2. The decoupling control method for hot air velocity and dehumidification negative pressure of the yarn drying machine according to claim 1, characterized in that, The control variables output by the hot air speed control loop and the dehumidification negative pressure control loop include hot air speed u1, hot air damper opening y1, dehumidification negative pressure u2, and negative pressure damper opening y2.

3. The decoupling control method for hot air velocity and dehumidification negative pressure of the filament drying machine according to claim 1, characterized in that, a The coordinates of the two sets of control variables obtained before and after a sampling unit time in four-dimensional space are respectively , The Euclidean distance is calculated using the norm based on four-dimensional coordinates: ； in, coordinates of a point in four-dimensional space Point coordinates The Euclidean distance between them; when At that time, it was assumed that the system was stable and the data did not undergo sudden changes.

4. The decoupling control method for hot air velocity and dehumidification negative pressure of the yarn drying machine according to claim 1, characterized in that, The static gain matrix of the wire drying machine control system is obtained using the process identification method, and the relative gain matrix is ​​obtained through matrix transformation, including: The transfer function between the control variables under PID control is obtained using the process identification method, where: Transfer function from hot air velocity to hot air damper opening The expression is: ； Where s is the Laplace transform operator, This represents the static gain from hot air velocity to hot air damper opening. The first inertial time parameter is the change from hot air velocity to hot air damper opening. The second inertial time parameter is the change from hot air velocity to hot air damper opening. This is the lag time parameter between the hot air velocity and the hot air damper opening. Transfer function of the opening degree of the exhaust negative pressure damper to the negative pressure damper The expression is: ； in, The static gain is the opening degree of the damper from negative pressure to negative pressure during dehumidification. The first inertial time parameter is the time from the negative pressure of the exhaust damper to the opening of the negative pressure damper. The second inertial time parameter is the time from the negative pressure of the exhaust damper to the opening of the negative pressure damper. The lag time parameter for the opening degree of the negative pressure damper during dehumidification; Transfer function from hot air velocity to negative pressure damper opening The expression is: ； in, This represents the static gain from hot air velocity to negative pressure damper opening. This is the inertial time parameter from the hot air velocity to the opening of the negative pressure damper. This is the lag time parameter from hot air velocity to negative pressure damper opening. Transfer function from hot air damper opening to dehumidification negative pressure The expression is: ； in, The static gain from the opening of the hot air damper to the negative pressure of the exhaust system. This is the inertial time parameter from the opening of the hot air damper to the negative pressure of the dehumidification. The lag time parameter from the opening of the hot air damper to the negative pressure of dehumidification; The static gain matrix K of the wire drying machine control system is obtained based on the transfer function between the control variables under PID control: ； The relative gain matrix is ​​calculated from the static gain matrix through matrix transformation. : ； in, This represents the relative gain from hot air velocity to hot air damper opening. This represents the relative gain from the opening of the hot air damper to the negative pressure of the exhaust system. This represents the relative gain from hot air velocity to negative pressure damper opening. H represents the relative gain of the damper opening from negative pressure to negative pressure, and H is the inverse of the static gain matrix K.

5. The decoupling control method for hot air velocity and dehumidification negative pressure of the filament drying machine according to claim 4, characterized in that, The constraints on the relative gain matrix include: ； 。 6. The decoupling control method for hot air velocity and dehumidification negative pressure of the yarn drying machine according to claim 1, characterized in that, The feedforward decoupling controller includes a transfer function for decoupling compensation of the influence of the negative pressure control of the exhaust air on the hot air velocity. and the transfer function used to decouple and compensate for the negative pressure effect of hot air velocity control. ; According to the principle of invariance, setting the disturbance to 0, we get: ； ； in, Let be the transfer function from hot air velocity to hot air damper opening under PID control. Let be the transfer function for the opening degree of the negative pressure damper during venting under PID control. Let be the transfer function from hot air velocity to negative pressure damper opening under PID control. It is the transfer function from the opening of the hot air damper to the negative pressure of dehumidification under PID control.

7. The decoupling control method for hot air velocity and dehumidification negative pressure of the yarn drying machine according to claim 6, characterized in that, when , , and Simplified to: ； ； in, The static gain from the opening of the hot air damper to the negative pressure of the exhaust system. The first inertial time parameter is the change from hot air velocity to hot air damper opening. Let be the second inertial time parameter from hot air velocity to hot air damper opening, and s be the Laplace transform operator. This represents the static gain from hot air velocity to hot air damper opening. This is the inertial time parameter from the opening of the hot air damper to the negative pressure of the dehumidification zone. This represents the static gain from hot air velocity to negative pressure damper opening. The first inertial time parameter is the time from the negative pressure of the exhaust damper to the opening of the negative pressure damper. The second inertial time parameter is the time from the negative pressure of the exhaust damper to the opening of the negative pressure damper. The static gain is the opening degree of the damper from negative pressure to negative pressure during dehumidification. This is the inertial time parameter from hot air velocity to negative pressure damper opening.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the decoupling control method for hot air velocity and dehumidification negative pressure of the drying machine as described in any one of claims 1 to 7.

Images