Fluid mixing and stirring device and method based on hyperchaotic mapping

Abstract

The invention discloses a fluid mixing and stirring device and method based on hyperchaotic mapping. The fluid mixing and stirring device comprises a PLC, a first servo unit for realizing positioning control, a second servo unit for realizing speed control, a stirring unit and a stirring tank, the PLC sends a positioning control pulse signal to the first servo unit at regular time and sends a speed control pulse signal to the second servo unit at the same time, and the first servo unit controls the stirring unit to stir materials in the stirring tank at a set rotating speed according to the positioning control pulse signal. Meanwhile, the second servo unit controls the stirring unit to stir the materials at the set position of the stirring tank according to the speed control pulse signal; the positioning control pulse signal and the speed control pulse signal are obtained by converting hyper-chaos parameters in the hyper-chaos sequence.

Description

Technical Field

[0001] The present invention belongs to the technical field of fluid mixing and stirring, and specifically relates to a fluid mixing and stirring device and method based on hyperchaotic mapping. Background Art

[0002] The thorough mixing of different types of liquids is an indispensable part of the production process in many industries such as metallurgy, chemical industry, and wastewater treatment. However, existing stirring devices still face many challenges in actual industrial applications. For example, when stirring mixed liquids with high viscosity and low Reynolds numbers, there is a problem of low mixing efficiency.

[0003] In order to solve the problem of low mixing efficiency, the main means at present is to increase the stirring speed. However, in the process of increasing the stirring speed, there are the following difficulties: (1) The stirring paddle has to withstand a large bending moment, and the material requirements for the stirring paddle are relatively stringent; (2) When a low-Reynolds number mixed liquid with high viscosity is stirred at a uniform speed, the liquid in the tank is in a laminar state, and stable symmetrical flow fields such as "annular isolation zone" and "column reflux" will be generated near the upper and lower parts of the stirring paddle. The existence of symmetrical flow fields will lead to uneven mixing of the stirred materials, low mixing efficiency, poor heat transfer effect, and huge energy consumption; (3) When dealing with shear-sensitive polymer materials, high-speed stirring will destroy the internal molecular structure.

[0004] In addition, most existing stirring devices are of an integrated type, which is not conducive to modularization, and the disassembly, assembly and maintenance of the entire device are relatively difficult.

[0005] In addition, existing stirring devices generally lack monitoring and control systems, and the production process relies on manual monitoring, which is not conducive to production efficiency or production safety. Summary of the invention

[0006] Purpose of the invention: In order to solve the problems existing in the existing stirring means and to solve the defects existing in the existing stirring devices, the present invention proposes a fluid mixing and stirring device and method based on hyperchaotic mapping, which uses a host computer to generate two-dimensional hyperchaotic state parameters, and the PLC converts the two-dimensional hyperchaotic state parameters into chaotic pulse signals and gives them to the servo driver. The servo driver sends corresponding instructions to drive the servo motor to generate chaotic state rotation, thereby realizing hyperchaotic stirring, which can effectively solve the problems of uneven fluid mixing and lack of in-situ production monitoring.

[0007] Technical solution: A fluid mixing and stirring device based on hyperchaotic mapping, comprising: a PLC, a first servo unit for realizing positioning control, a second servo unit for realizing speed control, a stirring unit and a stirring tank; The PLC periodically sends a positioning control pulse signal to the first servo unit and simultaneously sends a speed control pulse signal to the second servo unit. The first servo unit controls the stirring unit to stir the material in the stirring tank at a set speed according to the positioning control pulse signal, and simultaneously the second servo unit controls the stirring unit to stir the material at a set stirring tank position according to the speed control pulse signal. The positioning control pulse signal and the speed control pulse signal are obtained according to the transformation of the hyperchaotic parameters in the hyperchaotic sequence; The hyperchaotic sequence is obtained by following the steps below: Write a two-dimensional hyperchaotic map as shown below: ; In the formula, n Indicates the current iteration number, and Respectively represent n The mapping state after the iteration determines the speed and position of the stirring unit. represents the control parameters; The hyperchaotic parameters are intercepted from the two-dimensional hyperchaotic map, and the intercepted hyperchaotic parameters are normalized to obtain normalized hyperchaotic parameters. The hyperchaotic sequence is established using the normalized hyperchaotic parameters.

[0008] Furthermore, the above-mentioned normalization operation is performed on the intercepted hyperchaotic parameters to obtain normalized hyperchaotic parameters, and the specific operation includes: The following normalization equation is used to normalize the extracted hyperchaotic parameters to obtain the normalized hyperchaotic parameters: ; in, and They represent the minimum and maximum values ​​in the hyperchaotic sequence respectively, and min and max represent the normalized minimum and maximum dimension ranges.

[0009] Furthermore, it also includes: a first swirl spray gun arranged at the bottom of the stirring tank and a second side-blowing swirl spray gun arranged on the side wall of the stirring tank; the PLC controls whether the first swirl spray gun and the second swirl spray gun blow air into the stirring tank, and adjusts the airflow blowing amount of the first swirl spray gun and the second swirl spray gun.

[0010] Furthermore, it also includes a conductivity monitor, a pH value monitor and a liquid flow field structure image acquisition unit; The conductivity monitor is used to monitor the conductivity of the material in the stirring tank and feed the monitored conductivity back to the PLC; The pH value monitor is used to monitor the pH value of the material in the stirring tank and feed the monitored pH value back to the PLC; The liquid phase flow field structure image acquisition unit is used to acquire the liquid phase flow field structure image of the material in the stirring tank, and feed the acquired liquid phase flow field structure image back to the PLC; According to the conductivity, pH value and liquid phase flow field structure image, the first swirl spray gun and the second swirl spray gun are controlled to blow air into the stirring tank, and the airflow blowing amount of the first swirl spray gun and the second swirl spray gun is adjusted.

[0011] The present invention also discloses a fluid mixing and stirring method based on hyperchaotic mapping, comprising the following steps: Constructing the fluid mixing and stirring device based on hyperchaotic mapping disclosed above; Under the control of the first servo unit, the stirring unit stirs the material in the stirring tank at a set rotation speed. At the same time, under the control of the second servo unit, the stirring unit stirs the material at a set position in the stirring tank.

[0012] Beneficial effects: Compared with the prior art, the present invention has the following advantages: (1) As a nonlinear dynamic behavior, the hyperchaotic sequence generated by hyperchaotic mapping has strong randomness. Combining the hyperchaotic mapping algorithm with the fluid stirring device has important engineering value. The present invention implants a two-dimensional hyperchaotic mapping in the PLC, performs normalization operation, transmits the parameters to the servo driver to generate a chaotic pulse signal, and drives the servo motor to make the stirring blade and the fluid stirring device move along the servo motor. y The shaft drags the stirring paddle up and down to perform chaotic motion, forming chaotic stirring; at the same time, the electric regulating valves are used to control the swirl spray guns to spray swirl gas at the bottom and side of the stirring tank, and the swirl gas volume is adjusted in real time with variable frequency to make it pulsate periodically; during the stirring process, the bubbles collide with the stirring paddle and gradually fill the entire stirring tank, further preventing the formation of a mixed isolation zone, effectively improving the chaotic stirring effect; (2) The chaotic stirring of the present invention can be adjusted by combining the hyperchaotic signal with the stirring speed and the stirring liquid level, thereby greatly improving the stirring and mixing effect; (3) The present invention has a complete stirring operation system and monitoring control system, which can effectively realize the control and monitoring of the fluid mixing device, and by combining two-dimensional hyperchaotic mapping, it can better improve the fluid mixing efficiency and help achieve energy saving and emission reduction in the fluid mixing process; (4) The present invention can also be applied to chemical experiments to promote the full reaction of substances; to the food processing industry to prepare batters or mix raw materials of different flavors, including blending in the production process of liquor; to the stirring of dry powders, stirring pastes, liquid objects, granulation and other processes to help uniformly mix materials; to the pharmaceutical and medical device industries to mix detergents and water during the cleaning process to clean equipment and products; to the chemical, biopharmaceutical, hot pressing and other industries to uniformly mix polymer solutions, suspensions, colloids, etc.; and to the sewage treatment industry to remove impurities. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a work flow chart of the present invention; Figure 2 It is a structural schematic diagram of the fluid mixing and stirring device of the present invention; Figure 3 It is an oblique view of the fluid mixing and stirring device of the present invention; Figure 4 It is a side view of the fluid mixing and stirring device of the present invention; Figure 5 It is the calculation process diagram of sample entropy; Figure 6 The Lyapunov exponent spectrum and phase trajectory diagram of the hyperchaotic mapping used in the present invention; Figure 7 It is the chaotic speed sequence and chaotic liquid level sequence diagram; Figure 8 It is a schematic diagram of hyperchaotic speed control of the present invention; Fig. 9 This is a comparison diagram of the stirring effect of the present invention and the stirring effect of other stirring devices. DETAILED DESCRIPTION

[0014] The technical solution of the present invention is now further described in conjunction with the accompanying drawings and embodiments.

[0015] like Figure 1 The present embodiment proposes a fluid mixing and stirring device based on hyperchaotic mapping, which mainly includes: a PLC, a chaotic stirring module and a monitoring and control module. The PLC generates a series of strong random values, normalizes these strong random values ​​to a certain applicable range, and finally combines the normalized values ​​with the stirring speed and stirring position of the chaotic stirring module to achieve the effect of chaotic stirring.

[0016] Now let's further explain PLC.

[0017] The host computer 11 in the monitoring and control module is connected to the PLC 8 via the EtherCAT communication protocol network port. The host computer 11 is used to program the two-dimensional hyperchaotic mapping shown in formula (1) in the programming software of the PLC 8: ; In the formula, n is a natural number, indicating the current number of iterations. and Respectively represent n The mapping state after the iteration determines the rotation speed and position of the stirring unit, that is, the mapping state determines the rotation speed of the three-blade stirring paddle 18 and the moving distance of the ball screw 6. Represents a control parameter, specifically a parameter that controls dynamic characteristics.

[0018] The hyperchaotic parameters are intercepted from the two-dimensional hyperchaotic map, and the intercepted hyperchaotic parameters are normalized to obtain the normalized hyperchaotic parameters. The hyperchaotic sequence is established using the normalized hyperchaotic parameters, and then the speed and position of the stirring unit are randomly controlled. Specifically: The following normalization equation is used to scale the extracted hyperchaotic parameters to the required sequence diagram: ; in, and They represent the minimum and maximum values ​​in the hyperchaotic sequence respectively, and min and max represent the normalized minimum and maximum dimension ranges.

[0019] The normalized hyperchaotic parameters are stored in the global variable memory built into the PLC 8.

[0020] The normalized hyperchaotic parameters will be converted into instructions recognizable by the servo driver, and iteratively assigned to the speed adjustment function block and the absolute distance movement function block programmed in PLC 8 at specified intervals. The absolute distance movement function block and the speed adjustment function block will convert the hyperchaotic parameters into corresponding pulse signals, which are transmitted to the first servo driver 2 in the positioning control mode and the second servo driver 3 in the speed control mode through the network port respectively. The first servo driver 2 and the second servo driver 3 execute the corresponding pulse signals to drive the servo motors to achieve a hyperchaotic stirring effect.

[0021] Now combined Figure 5 and Figure 6 The chaotic effect produced by this embodiment is described. Generally speaking, the chaotic effect can be expressed by sample entropy, and the higher the complexity of the chaos, the better the chaotic effect, the stronger the randomness, and the more variable the stirring control.

[0022] Figure 5 The calculation process of sample entropy is shown, including: S1: Data preparation: The three-blade impeller 18 is updated using the hyperchaotic parameters, which is expressed as: ; In the formula, represents the total number of samples, represents the rotation speed of the three-blade stirring paddle 18; Indicates N Sub-sampled hyperchaotic parameters; S2: Hyperchaotic parameters Do a Fast Fourier Transform (FFT) to get ; In the formula, k Indicates k discrete frequencies; is the hyperchaotic parameter Frequency domain representation after fast Fourier transform; S3: Order ; S4: Calculate the discrete rate according to the following formula : ; S5: Order ; S6: Determine whether the following conditions are met: ; If satisfied, execute S4; if not satisfied, calculate the sample entropy according to the following formula : ; Using sample entropy The probability of a sequence generating a new pattern in a short period of time is measured to verify the high complexity and strong randomness of the two-dimensional hyperchaotic mapping used in this embodiment. The Lyapunov index spectrum of the two-dimensional hyperchaotic mapping is drawn. The Lyapunov index is an important basis for judging whether a chaotic system is chaotic. A two-dimensional system has two Lyapunov indexes (LE 1、 LE 2 ), if one is greater than 0, it means the system is in a chaotic state, and if two are greater than 0, it means the system is in a hyper-chaotic state. At this time, the complexity of the chaotic system will be excellent. Figure 6 As shown in (a), by LE 1 >0,LE 2 > 0, the two Lyapunov exponent parameters (LE 1、 LE 2 ) is greater than zero, which means that the system is in a hyperchaotic state. The system has strong randomness, and the parameters of the hyperchaotic part are obtained through analysis.

[0023] According to the two-dimensional hyperchaotic mapping formula, when ( x 0 , y 0 ) = (1, 0) and aWhen varying in [–3.4, 2.5], the mapping evolution includes periodic, chaotic, and hyperchaotic. a When [–2.7, –2.248], hyperchaos occurs; when a When it varies in [–2.248, –2.03], the mapping is chaotic; when a When it increases to [–2.03, –2.01], a small range of periodic windows is captured; a When it varies in [1.758, 1.882], the mapping has quasi-periodic oscillation behavior; when a The mapping is chaotic when varying in [1.892, 2.5], embedding two independent periodic windows [1.99, 2.115] and [2.333, 2.365].

[0024] like Figure 6 As shown in (b) in FIG. 1 , the two-dimensional hyperchaotic mapping used in this embodiment has strong randomness.

[0025] The chaotic speed sequence and chaotic liquid level sequence generated by the two-dimensional hyperchaotic mapping proposed in this embodiment are as follows: Figure 7 shown.

[0026] Specific processing such as Figure 8 As shown, the first servo driver 2 in the positioning control mode first adjusts the values ​​of the position loop and the speed loop, as well as their proportional gain, according to the motion mode, load inertia, acceleration and other conditions of the external load machinery. The frequency of the pulse input by the PLC 8 determines the magnitude of the rotation speed, the number of pulses determines the rotation angle, and the signal is converted into the corresponding position command. During the operation of the remaining two loops, the output current of the driver to the motor is finally detected by the Hoff device, and the negative feedback is given to the current setting for PID adjustment, so that the output current is close to equal to the set current, so that the stirring paddle reaches the effect of the set position. The second servo driver 3 in the speed control mode first appropriately adjusts the speed gain and speed integral, controls the rotation speed by the frequency of the pulse, and during the operation of the remaining current loop, the output current of the driver to the motor is also detected by the Hoff device, and the negative feedback is given to the current setting for PID adjustment, so that the output current is close to equal to the set current, so that the stirring paddle reaches the effect of the set speed. The chaotic stirring module is now further explained.

[0027] like Figure 2 , Figure 3 and Figure 4As shown, the chaotic stirring module proposed in this embodiment includes: a first servo motor 1, a first servo driver 2, a second servo driver 3, a second servo motor 4, a sliding table 5, a ball screw 6, a negative limit signal 7, a PLC 8, a host computer 11, an origin limit signal 12, a positive limit signal 13, a stirring tank 14, a bottom blowing swirl spray gun 15, a stirring fixed table 16, a side blowing swirl spray gun 17, a three-blade stirring paddle 18, a connecting shaft 19 and an electric regulating valve 22.

[0028] The specific connection relationship is: the three-blade stirring paddle 18 is connected to the rotor of the second servo motor 4 by using the connecting shaft 19, the first servo motor 1 drives the ball screw 6 to drive the sliding table 5 equipped with the second servo motor 4 to move to different liquid levels, the two servo motors are connected to their respective servo drivers through the network port, the first servo driver 2 and the second servo driver 3 are connected in series with each other through the network port, the second servo driver 3 is connected to the PLC 8 through the network port, the PLC 8 is connected to the host computer 11 through the network port for programming and control, and the host computer 11 selects and configures parameters of the servo configuration software through the serial port, and the parameter selection and configuration include but are not limited to: control mode selection, rigidity level setting, inertia ratio and motor rotation positive direction definition.

[0029] In this embodiment, a negative limit signal 7, an origin limit signal 12 and a positive limit signal 13 are respectively installed on the ball screw 6. The above limit signals are connected to the terminals of the first servo driver 2. Finally, the parameters of each limit signal are set in the servo configuration software on the host computer 11. By using these limit signals, the origin of the stirring shaft can be effectively found, and the dangerous stirring position can be stopped in time.

[0030] In this embodiment, a side-blowing swirl spray gun 17 is provided on the side wall of the stirring tank 14, and a bottom-blowing swirl spray gun 15 is provided at the bottom of the stirring tank 14. The air inlet ends of the side-blowing swirl spray gun 17 and the bottom-blowing swirl spray gun 15 are respectively connected to corresponding air inlet pipes, and an electric regulating valve 22 is provided above each air inlet pipe. The electric regulating valve 22 is connected to the PLC 8, and the airflow blowing amount is adjusted by real-time frequency conversion through the host computer 11.

[0031] The chaotic stirring module proposed in this embodiment can realize the current stirring speed adjustment, the current stirring liquid level adjustment and the swirl spray gun control. Specifically, it includes: The first servo driver 2 is controlled by the PLC 8 to drive the first servo motor 1, and the first servo motor 1 operates the ball screw 6 to make the three-blade stirring paddle 18 reach the required stirring liquid level. The second servo driver 3 drives the second servo motor 4, and the second servo motor 4 drives the three-blade stirring paddle 18 to stir the fluid. The three-blade stirring paddle 18 continues to stir the fluid at the current liquid level and the current speed for 6 seconds so as to smoothly reach the specified position.

[0032] This embodiment uses the negative limit signal 7, the origin limit signal 12, and the positive limit signal 13 to limit the movable range of the three-blade stirring paddle 18. The PLC 8 drives the second servo motor 4 through the second servo driver 3 to move the three-blade stirring paddle 18 to generate chaotic displacement within the range.

[0033] In this embodiment, the upper computer 11 controls the electric regulating valve 22 to adjust the closure of the current air inlet end and the size of the air flow.

[0034] The monitoring and control module is now further explained.

[0035] In order to facilitate the observation of the stirring condition of the mixed liquid in the stirring tank 14, the monitoring and control module uses the host computer 11 as the main end and connects a series of monitoring and control devices, which include but are not limited to: conductivity monitor 9, pH value monitor 10, laser transmitter 20 and high-speed camera 21.

[0036] The high-speed camera 21 is fixed to the upper side of the stirring tank 14 through a bracket, and the laser emitter 20 is fixed to the side of the stirring tank 14 through a bracket. The high-speed camera 21 of this embodiment cooperates with the laser emitter 20, and the emission intensity and irradiation angle of the laser emitter 20 are adjusted to put the high-speed camera 21 in the best state for obtaining video. Even at night, the current liquid flow field structure image and the liquid particle precipitation situation in the stirring tank 14 can be synchronously and clearly collected at high speed. The high-speed camera 21 transmits the liquid flow field structure image to the host computer 11 in real time, and the host computer 11 saves it.

[0037] The conductivity monitor 9 is connected to the PLC 8, and the probe of the conductivity monitor 9 is respectively placed in the top, middle and bottom of the material in the stirring tank 14, and the change of the conductivity of the material is monitored by the host computer 11. The pH value monitor 10 is connected to the PLC 8, and the probe of the pH value monitor 10 is placed in the material of the stirring tank 14, and the change of the pH value of the material is monitored by the host computer 11. According to the material conductivity value, pH value and liquid phase flow field structure image received by the host computer 11, the host computer 11 is used to run the management control program of the PLC 8 to achieve the control of the valve opening and closing size of the electric regulating valve 22 and the gas flow rate of the swirl spray gun. The host computer 11 is used to run the management control program of the PLC 8 to read the current speed of the servo motor, so as to set the optimal time for each chaotic sequence value currently applied to the stirring device to continue according to experience.

[0038] The fluid mixing and stirring device based on hyperchaotic mapping proposed in this embodiment implants a hyperchaotic mapping algorithm in the PLC 8, performs a normalization operation, transmits the parameters to the servo driver to generate a chaotic pulse signal, and drives the servo motor to make the stirring blade and the fluid mixing and stirring device move along the axis of the servo driver. yThe shaft drags the stirring paddle up and down to perform chaotic motion, forming chaotic stirring. The bottom and side of the stirring tank 14 are respectively controlled by electric regulating valves to control the swirl spray gun to spray swirl gas, and the swirl gas volume is adjusted in real time by frequency conversion to make it pulsate periodically. Fig. 9 A comparison diagram of the stirring effect achieved by the stirring device proposed in this embodiment and the stirring effect achieved by other stirring devices is shown. During the stirring process of the stirring device proposed in this embodiment, bubbles collide with the stirring paddle and gradually fill the entire stirring tank 14, further preventing the formation of a mixed isolation zone, and its chaotic stirring effect is better than the stirring effect achieved by other stirring devices.

Claims

1. A fluid mixing and stirring device based on hyperchaotic mapping, characterized in that: include: PLC, a first servo unit for realizing positioning control, a second servo unit for realizing speed control, a stirring unit and a stirring tank; The PLC periodically sends a positioning control pulse signal to the first servo unit and simultaneously sends a speed control pulse signal to the second servo unit. The first servo unit controls the stirring unit to stir the material in the stirring tank at a set speed according to the positioning control pulse signal, and simultaneously the second servo unit controls the stirring unit to stir the material at a set stirring tank position according to the speed control pulse signal. The positioning control pulse signal and the speed control pulse signal are obtained according to the transformation of the hyperchaotic parameters in the hyperchaotic sequence; The hyperchaotic sequence is obtained by following the steps below: Write a two-dimensional hyperchaotic map as shown below: ； In the formula, n Indicates the current iteration number, and Respectively represent n The mapping state after the iteration determines the speed and position of the stirring unit. represents the control parameters; The hyperchaotic parameters are intercepted from the two-dimensional hyperchaotic map, and the intercepted hyperchaotic parameters are normalized to obtain normalized hyperchaotic parameters. The hyperchaotic sequence is established using the normalized hyperchaotic parameters.

2. The fluid mixing and stirring device based on hyperchaotic mapping according to claim 1, characterized in that: The above-mentioned normalization operation is performed on the intercepted hyperchaotic parameters to obtain normalized hyperchaotic parameters, and the specific operation includes: The following normalization equation is used to normalize the extracted hyperchaotic parameters to obtain the normalized hyperchaotic parameters: ； in, and They represent the minimum and maximum values ​​in the hyperchaotic sequence respectively, and min and max represent the normalized minimum and maximum dimension ranges.

3. The fluid mixing and stirring device based on hyperchaotic mapping according to claim 1, characterized in that: Also includes: A first swirl spray gun disposed at the bottom of the stirring tank and a second side-blowing swirl spray gun disposed on the side wall of the stirring tank; The PLC controls whether the first swirl spray gun and the second swirl spray gun blow air into the stirring tank, and adjusts the airflow blowing amount of the first swirl spray gun and the second swirl spray gun.

4. The fluid mixing and stirring device based on hyperchaotic mapping according to claim 3 is characterized in that: It also includes a conductivity monitor, a pH value monitor and a liquid phase flow field structure image acquisition unit; The conductivity monitor is used to monitor the conductivity of the material in the stirring tank and feed the monitored conductivity back to the PLC; The pH value monitor is used to monitor the pH value of the material in the stirring tank and feed the monitored pH value back to the PLC; The liquid phase flow field structure image acquisition unit is used to acquire the liquid phase flow field structure image of the material in the stirring tank, and feed the acquired liquid phase flow field structure image back to the PLC; According to the conductivity, pH value and liquid phase flow field structure image, the first swirl spray gun and the second swirl spray gun are controlled to blow air into the stirring tank, and the airflow blowing amount of the first swirl spray gun and the second swirl spray gun is adjusted.

5. A fluid mixing and stirring method based on hyperchaotic mapping, characterized in that: The following steps are involved: Construct a fluid mixing and stirring device based on hyperchaotic mapping as described in any one of claims 1 to 4; Under the control of the first servo unit, the stirring unit stirs the material in the stirring tank at a set rotation speed. At the same time, under the control of the second servo unit, the stirring unit stirs the material at a set position in the stirring tank.

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