A method for monitoring the sedimentation of magnetorheological fluid based on machine vision

Abstract

The invention relates to the field of magnetorheological fluid sedimentation technology, and in particular to a magnetorheological fluid sedimentation monitoring device and monitoring method based on machine vision, comprising an infrared night vision wide-angle camera, a high-power parallel light source, a carrier, an analog-to-digital converter and a computer data processor, wherein the carrier is used to carry the magnetorheological fluid, the infrared night vision wide-angle camera is arranged in parallel and passes through the carrier, the high-power parallel light source is connected to the carrier, the high-power parallel light source is aligned with the infrared night vision wide-angle camera, the infrared night vision wide-angle camera is connected to the analog-to-digital converter, and the analog-to-digital converter is connected to the computer data processor, thereby solving the technical problems in the prior art that a magnetic field is introduced to interfere with the sedimentation of the magnetorheological fluid, and the monitoring methods such as the potential method and the inductance method are complicated and easily interfere with the magnetorheological fluid in the sedimentation process.

Description

Technical Field

[0001] The invention relates to the technical field of magnetorheological fluid sedimentation, and in particular to a magnetorheological fluid sedimentation monitoring method based on machine vision. Background Art

[0002] Magnetorheological fluid is a typical intelligent composite material, a suspension system composed of a magnetizable dispersed phase and a non-magnetic continuous phase. Under the action of an external magnetic field, its rheological properties can undergo a reversible transformation in milliseconds. Due to this property, it is widely used in shock absorption, polishing, construction, automobiles and other fields. However, the huge density difference between magnetic particles and the continuous phase causes the magnetorheological fluid to inevitably settle, thus limiting its application in various fields.

[0003] The magnetorheological fluid sedimentation monitoring technology can play an early warning role when the magnetorheological fluid sedimentation occurs, and has a guiding role in the sedimentation and redispersion of the magnetorheological fluid. Therefore, the magnetorheological fluid monitoring technology is of great significance to solving the sedimentation stability problem of the magnetorheological fluid. At present, a variety of methods have been developed to monitor the sedimentation problem of the magnetorheological fluid, including visual method, inductance method, thermal conductivity method, potential method, etc. The visual method analyzes the magnetorheological fluid sedimentation by observing the changes in the mud line, but it is impossible to monitor the sedimentation of the magnetorheological fluid below the mud line; the thermal conductivity method obtains the change of the thermal conductivity of the magnetorheological fluid by installing a temperature measuring needle at a fixed position, but it is necessary to ensure the thermal environment stability of the magnetorheological fluid. CN106596660A and CN106546517A use the capacitance method to monitor the sedimentation of the magnetorheological fluid very well.

[0004] However, when the above method is adopted, a magnetic field will be introduced to interfere with the sedimentation of the magnetorheological fluid, and the monitoring methods such as the potential method and the inductance method are complicated and easily interfere with the magnetorheological fluid during the sedimentation process. Summary of the invention

[0005] The purpose of the present invention is to provide a method for monitoring the sedimentation of magnetorheological fluid based on machine vision, aiming to solve the technical problems in the prior art that the magnetic field will be introduced to interfere with the sedimentation of magnetorheological fluid, and the monitoring methods such as the potential method and the inductance method are complex and easily interfere with the magnetorheological fluid during the sedimentation process.

[0006] To achieve the above-mentioned purpose, the present invention adopts a magnetorheological fluid sedimentation monitoring device based on machine vision, including an infrared night vision wide-angle camera, a high-power parallel light source, a carrier, an analog-to-digital converter and a computer data processor, wherein the carrier is used to carry the magnetorheological fluid, the infrared night vision wide-angle camera is arranged in parallel and passes through the carrier, the high-power parallel light source is connected to the carrier, the high-power parallel light source is aligned with the infrared night vision wide-angle camera, the infrared night vision wide-angle camera is connected to the analog-to-digital converter, and the analog-to-digital converter is connected to the computer data processor.

[0007] Wherein, the carrier includes a base and a magnetorheological fluid container, the magnetorheological fluid container is arranged on the base, and the magnetorheological fluid container is used to carry the magnetorheological fluid.

[0008] The infrared night vision wide-angle camera is used to obtain a magnetorheological fluid sedimentation time diagram, and the analog-to-digital converter is used to convert the obtained magnetorheological fluid sedimentation time diagram and process it through the computer data processor.

[0009] The present invention also provides a method for monitoring the sedimentation of a magnetorheological fluid based on machine vision, comprising the following steps:

[0010] Step 1: Obtain a magnetorheological fluid sedimentation monitoring device based on machine vision, the monitoring device comprising an infrared night vision wide-angle camera, a high-power parallel light source, a carrier, an analog-to-digital converter and a computer data processor, the carrier being used to carry magnetorheological fluid, the infrared night vision wide-angle camera being arranged in parallel and passing through the carrier, the high-power parallel light source being connected to the carrier, the high-power parallel light source being aligned with the infrared night vision wide-angle camera, the infrared night vision wide-angle camera being connected to the analog-to-digital converter, the analog-to-digital converter being connected to the computer data processor, the carrier comprising a base and a magnetorheological fluid container, the magnetorheological fluid container being arranged on the base, the magnetorheological fluid container being used to carry magnetorheological fluid, the infrared night vision wide-angle camera being used to obtain a magnetorheological fluid sedimentation time diagram, the analog-to-digital converter being used to convert the obtained magnetorheological fluid sedimentation time diagram and then process it through the computer data processor;

[0011] Step 2: obtaining a magnetorheological fluid sedimentation time diagram through the infrared night vision wide-angle camera;

[0012] Step 3: Preprocess the acquired moment image by the computer data processor and convert it into a grayscale image to accurately obtain the grayscale value of each area;

[0013] Step 4: Substitute the constant K obtained from the initial concentration φ(t=0) and the calibration experiment into the equation

[0014]

[0015] Then the concentration of the magnetorheological fluid in this area at different times can be deduced;

[0016] Step 5: thereby realizing non-destructive, calibration-free online in-situ monitoring of the magnetorheological fluid sedimentation process.

[0017] The present invention discloses a method for monitoring the sedimentation of a magnetorheological fluid based on machine vision. The magnetorheological fluid container is a hollow cylinder, comprising an inner cylinder and an outer cylinder arranged concentrically. A magnetorheological fluid injection port is arranged on the top of the inner cylinder. The wall of the outer cylinder is coated with a black light-absorbing coating. The left middle wall of the inner cylinder and the outer cylinder are respectively provided with a 2.2 cm circular hole. The infrared night vision wide-angle camera is arranged in parallel and passes through the circular holes on the left middle wall of the inner cylinder and the outer cylinder of the magnetorheological fluid container. Sealing rings are respectively arranged at the connection. The high-power parallel light source is located in the inner cylinder of the magnetorheological fluid container and is close to the inner cylinder wall. When monitoring is performed specifically, the magnetorheological fluid sedimentation time map is first obtained by the infrared night vision wide-angle camera. The image preprocessing work is performed on the obtained time map by the computer data processor, and it is converted into a grayscale image to accurately obtain the grayscale value of each area. The initial concentration φ (t=0) condition and the constant K fitted by the calibration experiment are substituted into the equation

[0018]

[0019] The concentration of the magnetorheological fluid in this area at different times can be deduced, thereby realizing non-destructive, calibration-free online in-situ monitoring of the magnetorheological fluid sedimentation process. In this way, the technical problems in the prior art that the magnetic field will be introduced to interfere with the magnetorheological fluid sedimentation, and the monitoring methods such as the potential method and the inductance method are complex and easily interfere with the magnetorheological fluid during the sedimentation process are solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 It is a structural schematic diagram of magnetorheological fluid sedimentation monitoring based on machine vision of the present invention.

[0022] Figure 2 The present invention is a flow chart of a magnetorheological fluid sedimentation monitoring method based on machine vision.

[0023] 1-infrared night vision wide-angle camera, 2-high-power parallel light source, 3-magnetorheological fluid container, 4-base, 5-analog-digital converter, 6-computer data processing device. DETAILED DESCRIPTION

[0024] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0025] See also Figure 1 , Figure 1 It is a structural schematic diagram of the magnetorheological fluid sedimentation monitoring based on machine vision of the present invention. The present invention provides a magnetorheological fluid sedimentation monitoring device based on machine vision: comprising an infrared night vision wide-angle camera 1, a high-power parallel light source 2, a carrier, an analog-to-digital converter and a computer data processor 6, wherein the carrier is used to carry the magnetorheological fluid, the infrared night vision wide-angle camera 1 is arranged in parallel and passes through the carrier, the high-power parallel light source 2 is connected to the carrier, the high-power parallel light source 2 is aligned with the infrared night vision wide-angle camera 1, the infrared night vision wide-angle camera 1 is connected to the analog-to-digital converter, and the analog-to-digital converter is connected to the computer data processor 6;

[0026] The carrier includes a base 4 and a magnetorheological fluid container 3, wherein the magnetorheological fluid container 3 is disposed on the base 4 and is used to carry magnetorheological fluid;

[0027] The infrared night vision wide-angle camera 1 is used to obtain a magnetorheological fluid sedimentation time diagram, and the analog-to-digital converter is used to convert the obtained magnetorheological fluid sedimentation time diagram and process it through the computer data processor 6;

[0028] In this embodiment, the magnetorheological fluid container 3 is a hollow cylinder, including an inner cylinder and an outer cylinder arranged concentrically, a magnetorheological fluid injection port is arranged on the top of the inner cylinder, the wall of the outer cylinder is coated with black light-absorbing paint, and a 2.2 cm circular hole is arranged on the left middle wall of the inner cylinder and the outer cylinder respectively. The infrared night vision wide-angle camera 1 is arranged in parallel and passes through the circular holes on the left middle wall of the inner cylinder and the outer cylinder of the magnetorheological fluid container 3, and sealing rings are arranged at the connection. The high-power parallel light source 2 is located in the inner cylinder of the magnetorheological fluid container 3 and is close to the inner cylinder wall. When monitoring is carried out specifically, the magnetorheological fluid sedimentation time diagram is first obtained by the infrared night vision wide-angle camera 1, and the image preprocessing work is performed on the obtained time diagram by the computer data processor 6, and it is converted into a grayscale image to accurately obtain the grayscale value of each area. The initial concentration φ (t=0) condition and the constant K fitted by the calibration experiment are substituted into the equation

[0029]

[0030] The concentration of the magnetorheological fluid in this area at different times can be deduced, thereby realizing non-destructive, calibration-free online in-situ monitoring of the magnetorheological fluid sedimentation process. In this way, the technical problems in the prior art that the magnetic field will be introduced to interfere with the magnetorheological fluid sedimentation, and the monitoring methods such as the potential method and the inductance method are complex and easily interfere with the magnetorheological fluid during the sedimentation process are solved.

[0031] See also Figure 2 , Figure 2 : is a flow chart of a magnetorheological fluid sedimentation monitoring method based on machine vision of the present invention. The present invention also provides a magnetorheological fluid sedimentation monitoring method based on machine vision, which is applied to the magnetorheological fluid sedimentation monitoring device based on machine vision as described above, and comprises the following steps:

[0032] Step 1: According to the Kynch sedimentation theory, the sedimentation velocity of MRF particles at any position is assumed to depend only on the dispersed phase concentration at that position, and the particle concentration moves only along the z direction. Therefore, the particle mass change of a certain microelement inside the MRF material can be expressed as formula 1:

[0033]

[0034] Step 2: In step 1, ρ is the dispersed phase density, v s (φ) is the particle settling velocity, which can be expressed as follows according to the Vesilind velocity model:

[0035]

[0036] Step 3: In step 2, v0 is the maximum sedimentation velocity of the ferromagnetic dispersed phase, k1 is the regional sedimentation characteristic constant, and the concentration change rate can be obtained according to equations 1 and 2: The relationship with particle concentration (φ) is as follows:

[0037]

[0038] Step 4: The transmittance of the MRF material is closely related to the concentration of the MRF particles. According to the Lambert-Beer law, the transmittance T of the MRF material can be expressed as formula 4:

[0039]

[0040] Step 5. In step 4, φ is the particle concentration of MRF, I out and I in are the transmitted radiation flux and incident radiation flux of the MRF microelement under the external light environment, respectively, and k2 is the molar absorption coefficient of the material. Transforming equation 4 yields:

[0041]

[0042] Step 6: The gray value D at the microelement sensed by the photosensitive element is in direct proportion to the outgoing radiation flux, as shown in Formula 6:

[0043] D=αI out ;

[0044] Step 7. In step 6, D is the gray value output by the micro-element point of the image sensor, which is a dimensionless physical quantity, and α is an undetermined constant determined by the device parameters of the image sensor system. Arranging equations 5 and 6, we can get

[0045] Formula 7:

[0046]

[0047] Step 8: Derivative of equation 7, i.e. gray value change rate v D Formula 8:

[0048]

[0049] Step 9: Substituting equation 3 into equation 8, we can get the gray value change rate v D Another way to express Equation 9 is:

[0050]

[0051] Step 10: Fit the unknown constants in Formula 9 through standard experiments to establish the corresponding relationship between the pixel grayscale of each point and the concentration of the point during the MRF sedimentation process. However, in actual tests, the magnetorheological fluid material may be affected by the wall hanging phenomenon, which will affect the parameter I in Formula 9. inand k2 change when the external working environment changes, which seriously affects the accuracy of recognition. In order to eliminate this influence, this method sets an equal fitting constant between the sampling image time interval Δt of each sedimentation process and introduces the relative gray value change rate v r , this physical quantity represents the ratio of the grayscale change rate at two moments in a single sedimentation process, which can be expressed by the following formula 10:

[0052]

[0053] Step 11: In step 10, K = k1 + k2, and equation 10 is an implicit iterative equation for the concentration change over time during the sedimentation process. The constant K and the initial concentration φ (t = 0) condition can be fitted through the calibration experiment, and the grayscale change rate v of each grayscale can be tested through the acquisition system. D (φ), the concentration distribution of the MRF sedimentation process can be identified dynamically and without calibration through an iterative method.

[0054] Beneficial effects of the present invention:

[0055] 1. Aiming at the problem of magnetorheological fluid sedimentation, this monitoring device is based on machine vision technology. The infrared night vision wide-angle lens is installed in the middle position of the side wall of the magnetorheological fluid container 3 and the high-power parallel light source 2 is set on the opposite side to obtain the internal magnetorheological fluid image at different times. Since the transmitted light intensity will change with the change of magnetorheological fluid concentration, the grayscale value of the acquired image will also change. Therefore, the change of grayscale value is used to characterize the sedimentation state of the magnetorheological fluid. Based on this, the online in-situ monitoring of the sedimentation process of the magnetorheological fluid is realized.

[0056] 2. In order to solve the problem that the monitoring method and equipment may affect the sedimentation process of the magnetorheological fluid or the magnetorheological fluid itself when monitoring the sedimentation process of the magnetorheological fluid, the present invention characterizes the sedimentation state of the MRF according to the change of light intensity passing through the internal magnetorheological fluid and monitors it accordingly. Therefore, this monitoring device will not affect the sedimentation process of the magnetorheological fluid and the magnetorheological fluid itself, thereby realizing non-invasive and non-destructive monitoring of the sedimentation process of the magnetorheological fluid.

[0057] 3. In order to solve the problems of magnetorheological fluid sedimentation monitoring methods and devices having high overall costs, being inconvenient to carry or requiring monitoring in a specific laboratory environment, the present invention is composed of the infrared night vision wide-angle lens, the high-power parallel light source 2, the analog-to-digital converter, and the magnetorheological fluid container 3, so that the overall device has low cost, is easy to carry, and does not require monitoring in a specific laboratory environment.

[0058] 4. In order to solve the problem that magnetorheological fluid sedimentation monitoring methods and devices need to be calibrated in advance before monitoring, the present invention is based on the Kynch sedimentation theory and derives the MRF transmittance formula according to the Lambert-Beer law. Combined with the relationship between the image grayscale value and the photosensitive element, the relationship between the image grayscale value and the MRF concentration is derived. By introducing the relative grayscale value change rate to represent the ratio of the grayscale change rate at two moments in a single sedimentation process, the monitoring of the MRF sedimentation process without calibration is realized.

[0059] What is disclosed above is only a preferred embodiment of the present invention, and it certainly cannot be used to limit the scope of rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of the above embodiment and equivalent changes made according to the claims of the present invention still fall within the scope of the invention.

Claims

1. A method for monitoring the sedimentation of magnetorheological fluid based on machine vision, characterized in that: The steps include: Step 1, obtaining a magnetorheological fluid sedimentation monitoring device based on machine vision, the monitoring device comprising an infrared night vision wide-angle camera, a high-power parallel light source, a carrier, an analog-to-digital converter and a computer data processor, the carrier being used to carry magnetorheological fluid, the infrared night vision wide-angle camera being arranged in parallel and passing through the carrier, the high-power parallel light source being connected to the carrier, the high-power parallel light source being aligned with the infrared night vision wide-angle camera, the infrared night vision wide-angle camera being connected to the analog-to-digital converter, the analog-to-digital converter being connected to the computer data processor, the carrier comprising a base and a magnetorheological fluid container, the magnetorheological fluid container being arranged on the base, the magnetorheological fluid container being used to carry magnetorheological fluid, the infrared night vision wide-angle camera being used to obtain a magnetorheological fluid sedimentation time diagram, the analog-to-digital converter being used to convert the obtained magnetorheological fluid sedimentation time diagram and then process it through the computer data processor; Step 2: obtaining a magnetorheological fluid sedimentation time diagram through the infrared night vision wide-angle camera; Step 3: Preprocess the acquired moment image by the computer data processor and convert it into a grayscale image to accurately obtain the grayscale value of each area; Step 4: Substitute the constant K obtained from the initial concentration φ(t=0) and the calibration experiment into the equation Then the concentration of the magnetorheological fluid in this area at different times can be deduced; Step 5: thereby realizing non-destructive, calibration-free online in-situ monitoring of the magnetorheological fluid sedimentation process.

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