Non-360° Rotational Scanning Capacitive Tomography Imaging Device and Its Image Reconstruction Method

Abstract

The application relates to a non-360-degree rotary scanning type capacitance tomography device, which is structurally characterized in that an insulating rotating drum is coaxially connected to the rotating part of a hollow rotating table, a plurality of capacitance detection electrode plates are uniformly distributed on the outer wall of the insulating rotating drum, a radial shielding electrode is arranged between every two adjacent capacitance detection electrode plates, axial shielding electrodes are arranged at the two ends of the plurality of capacitance detection electrode plates, and a shielding cover is arranged outside the capacitance detection electrode plates. The non-360-degree rotary scanning type capacitance tomography device can obtain more detection capacitance projection data under the premise of keeping the difficulty of the original capacitance measurement circuit and the anti-noise interference performance of the capacitance tomography device without changing the size and quantity of the capacitance detection electrode plates, and can overcome the underdetermination of the capacitance tomography system to a certain extent.

Description

Technical Field

[0001] This invention relates to a non-360º rotating scanning capacitance tomography device and its image reconstruction method, belonging to the field of process tomography technology. Background Technology

[0002] Capacitance tomography (CTO) is a type of electrical tomography. Developed and refined in the mid-to-late 1980s, it's a process imaging technique used for detecting parameters in multiphase flow. Due to its advantages such as non-invasiveness, fast response, and low cost, it has become a focus of attention both domestically and internationally. The basic idea of ​​CTO is to measure the capacitance values ​​between all electrode combinations surrounding the measured area and then use an image reconstruction algorithm to infer the distribution of the medium inside the pipe.

[0003] In the prior art, application number 201310420106.2, entitled "Capacitive Tomography Imaging Sensor with Double-Layer Rotating Electrodes", was published on September 13, 2013. This invention provides a capacitive tomography imaging sensor with double-layer rotating electrodes. From the content of this invention, the following problems exist: (1) The bottom of the inner and outer rotating structures of this invention is provided with a fixed platform, so it cannot be installed on the actual measurement output pipe; (2) Due to the use of inner and outer rotating structures, different combinations are used for measurement, resulting in excessively long measurement time, which makes it difficult to meet the needs of real-time measurement; (3) Since the inner and outer rotating mechanisms are attached with excitation electrodes and detection electrodes, and the two electrodes are not on the same rotating surface, the imaging accuracy on the pipe cross section is affected; (4) At least one excitation electrode is attached to the inner wall of the inner rotating tube of this invention, and the outer rotating tube At least one measuring electrode is adhered to the inner wall, which adds a rotating channel between the excitation electrode and the measuring electrode, thereby reducing the sensitivity of the object field and easily causing measurement errors; (5) Due to the rotation of the inner and outer two-layer structure, the leads of the excitation electrode and the detection electrode are easily entangled, thereby causing damage to the measurement circuit and easily causing noise interference; (6) Although the invention increases the capacitance projection data, there are problems such as the excitation electrode and the detection electrode not being on the same rotating surface, and how to measure and process the sensitivity field at different rotation positions. At the same time, the invention does not provide a solution on how to perform imaging. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a non-360º rotating scanning capacitance tomography device. This non-360º rotating scanning capacitance tomography device can obtain more detection capacitance projection data without changing the size and number of capacitance detection plates, while maintaining the difficulty of the original capacitance measurement circuit and the anti-noise interference performance of the capacitance tomography device. It overcomes the understability of the capacitance tomography system to a certain extent.

[0005] To solve the above problems, the specific technical solution of the present invention is as follows: A non-360º rotating scanning capacitance tomography device includes a hollow turntable and a capacitance sensor module; the capacitance sensor module structure includes: an insulating rotating cylinder coaxially connected to the rotating part of the hollow turntable, a plurality of capacitance detection plates evenly distributed on the circumference of the outer wall of the insulating rotating cylinder, a radial shielding electrode provided between each pair of adjacent capacitance detection plates, and an axial shielding electrode provided at both ends of the plurality of capacitance detection plates; a shielding cover is provided outside the capacitance detection plates.

[0006] The through hole in the middle of the hollow turntable is equal to the inner diameter of the insulating cylinder, and the hollow turntable and the insulating cylinder are jointly arranged on the outer circumference of the transmission pipeline to be tested.

[0007] The hollow turntable drives the insulating drum to rotate at a maximum angle of 360º / N, where N is the number of capacitor detection plates.

[0008] The axial shielding electrode, radial shielding electrode, and capacitance detection plate are plate-type structures, and their inner surfaces are completely in contact with the insulating rotating cylinder.

[0009] The hollow turntable is externally equipped with a data acquisition and control module and an imaging computer. The output signal of the capacitance sensor module is input into the data acquisition and control module, and after data processing, it is sent to the imaging computer for imaging. The control signal of the imaging computer is input into the data acquisition and control module, and the data acquisition and control module controls the rotation of the hollow turntable and the acquisition of capacitance detection signals at the corresponding positions.

[0010] An image reconstruction method using a non-360º rotating scanning capacitance tomography device includes the following steps:

[0011] 1) Since the maximum rotation angle of the hollow rotary table is 360º / N, where N is the number of capacitor detection plates, the maximum rotation angle 360º / N is divided into several angle points according to the specific detection environment. The angle between each two adjacent angle points is 360º / N / m, where m is a natural number.

[0012] 2) Obtain the sensitivity field of the capacitance tomography system at each angle point in advance;

[0013] 3) Under the control of the data acquisition and control module, the hollow rotary table rotates point by point to the set angle position. Each time the hollow rotary table reaches the angle position, each capacitor detection plate measures a set of capacitance values ​​at the corresponding angle position through the data acquisition and control module, and sends the data to the imaging computer for processing.

[0014] 4) When the hollow rotary table rotates from 0° to 360° / N point by point, after the capacitance measurement at each angle point is completed, the capacitance values ​​measured by each capacitance detection plate at all angle points are spliced ​​into a column vector; and the sensitivity fields at the corresponding angle points are spliced ​​in the order of this column vector to form a new sensitivity field matrix. Then, a certain image reconstruction algorithm is used to calculate and obtain the required reconstructed image.

[0015] This application employs the aforementioned structure, enabling online pipeline inspection. Without altering the size and number of capacitance detection plates, it obtains more capacitance projection data, thus overcoming, to some extent, the underdeterminacy of capacitance tomography systems. Although this method increases the capacitance projection data, it does not increase the complexity of the capacitance measurement circuit, nor does it reduce the noise immunity of existing capacitance tomography devices. This invention significantly improves the quality of reconstructed images, making the reconstructed medium distribution closer to the true distribution. The device invention has the advantages of ease of fabrication and easy image reconstruction. This also provides a new approach and means for the research and application of process tomography, possessing significant practical application value. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a non-360º rotating scanning capacitance tomography device.

[0017] Figure 2 for Figure 1 AA sectional view.

[0018] Figure 3 This is a schematic diagram of the control system. Detailed Implementation

[0019] like Figure 1 and Figure 2 As shown, a non-360º rotating scanning capacitance tomography device includes a hollow turntable 1 and a capacitance sensor module 2. The capacitance sensor module 2 includes an insulating rotating cylinder 6 coaxially connected to the rotating part of the hollow turntable 1. A plurality of capacitance detection plates 9 are evenly distributed around the outer circumference of the insulating rotating cylinder 6. A radial shielding electrode 8 is provided between each pair of adjacent capacitance detection plates 9. An axial shielding electrode 7 is provided at both ends of the plurality of capacitance detection plates 9. A shielding cover 5 is provided outside the capacitance detection plates 9.

[0020] The through hole in the middle of the hollow turntable 1 is equal to the inner diameter of the insulating rotating cylinder 6, and the hollow turntable 1 and the insulating rotating cylinder 6 are jointly arranged on the outer circumference of the transmission pipeline to be tested.

[0021] The hollow turntable 1 drives the insulated rotating drum 6 to rotate a maximum angle of 360º / N, where N is the number of capacitance detection plates. Each capacitance detection plate acquires capacitance projection data at various locations around the pipe.

[0022] The axial shielding electrode 7, the radial shielding electrode 8, and the capacitance detection plate 9 are plate structures, and their inner surfaces are completely in contact with the insulating rotating cylinder 6.

[0023] like Figure 3 As shown, the hollow turntable 1 is externally equipped with a data acquisition and control module 3 and an imaging computer 4. The output signal of the capacitance sensor module 2 is input into the data acquisition and control module 3, and after data processing, it is transmitted to the imaging computer 4 for imaging. The control signal of the imaging computer 4 is input into the data acquisition and control module 3, and the data acquisition and control module 3 controls the rotation of the hollow turntable 1 and the acquisition of capacitance detection signals at corresponding positions. The data acquisition and control module 3 is used to provide voltage excitation for the capacitance excitation plate, detection scanning of the detection plate, and acquisition and transmission of capacitance measurement data; it also provides control signals for the rotation of the hollow turntable.

[0024] A method for image reconstruction using a non-360º rotating scanning capacitance tomography device includes the following steps:

[0025] 1) Since the maximum rotation angle of the hollow rotary table 1 is 360º / N, where N is the number of capacitor detection plates, the maximum rotation angle can be divided into several angle points according to the specific detection requirements. The angle between each two adjacent angle points is 360º / N / m, where m is a natural number. In this embodiment, N=8, so the maximum rotation angle is 45°. At the same time, m=9 is set, so the angle between the angle points is 5°.

[0026] 2) Obtain the sensitivity field of the capacitance tomography system at each angle point in advance;

[0027] 3) Under the control of the data acquisition and control module 3, the hollow rotary table 1 rotates 5° point by point to the set angle point. Each time the hollow rotary table 1 reaches the angle point, each capacitor detection plate 9 measures a set of capacitance values ​​at the corresponding angle point through the data acquisition and control module 3 and sends the data to the imaging computer 4 for processing.

[0028] 4) When the hollow rotary table 1 rotates from 0° to 45° point by point, after the capacitance measurement at each angle point is completed, the capacitance values ​​measured by each capacitance detection plate 9 at all angle points are spliced ​​into a column vector, and the sensitivity fields at the corresponding angle points are spliced ​​in the order of this vector to form a new sensitivity field matrix. Then, traditional algorithms (such as LBP algorithm, Landweber algorithm, Tikhonov algorithm, etc.) are used for calculation, so that the required reconstructed image can be obtained.

[0029] The above description is merely a preferred embodiment of the present invention, and the method of the present invention can also be applied to other tomographic imaging systems such as electromagnetic tomography and electrical impedance tomography. It should be noted that those skilled in the art can make various modifications and improvements without departing from the principles of the present invention, and these modifications and improvements should also be considered within the scope of protection of the present invention.

Claims

1. An image reconstruction method for a non-360º rotating scanning capacitance tomography device, characterized in that... Includes the following steps: 1) Since the maximum rotation angle of the hollow rotary table (1) is 360º / N, where N is the number of capacitor detection plates, the maximum rotation angle 360º / N is divided into several angle points according to the specific detection environment. The angle between each two adjacent angle points is 360º / N / m, where m is a natural number. 2) Obtain the sensitivity field of the capacitance tomography system at each angle point in advance; 3) Under the control of the data acquisition and control module (3), the hollow rotary table (1) rotates point by point to the set angle position. Each time the hollow rotary table (1) reaches the angle position, each capacitor detection plate (9) measures a set of capacitance values ​​at the corresponding angle position through the data acquisition and control module (3) and sends the data to the imaging computer (4) for processing. 4) When the hollow rotary table (1) rotates from 0° to 360° / N point by point, after the capacitance measurement work at each angle point is completed, the capacitance values ​​measured by each capacitance detection plate (9) at all angle points are spliced ​​into a column vector; and the sensitivity field of the corresponding angle point is spliced ​​in the order of this column vector to form a new sensitivity field matrix. Then, a certain image reconstruction algorithm is used to calculate and the required reconstructed image can be obtained. The non-360º rotating scanning capacitance tomography device includes a hollow turntable (1) and a capacitance sensor module (2). The capacitance sensor module (2) includes an insulating cylinder (6) coaxially connected to the rotating part of the hollow turntable (1). Several capacitance detection plates (9) are evenly distributed around the outer circumference of the insulating cylinder (6). A radial shielding electrode (8) is provided between each pair of adjacent capacitance detection plates (9). An axial shielding electrode (7) is provided at both ends of the several capacitance detection plates (9). A shielding cover (5) is provided outside the capacitance detection plates (9). The hollow turntable (1) drives the insulating cylinder (6) to rotate at a maximum angle of 360º / N, where N is the number of capacitance detection plates. The axial shielding electrode (7), radial shielding electrode (8), and capacitance detection plates (9) are plate structures, and their inner surfaces are completely in contact with the insulating cylinder (6).

2. The image reconstruction method of the non-360º rotating scanning capacitance tomography device as described in claim 1, characterized in that: The through hole in the middle of the hollow turntable (1) is equal to the inner diameter of the insulating cylinder (6), and the hollow turntable (1) and the insulating cylinder (6) are both set on the outer circumference of the transmission pipeline to be tested.

3. The image reconstruction method of the non-360º rotating scanning capacitance tomography device as described in claim 1, characterized in that: The hollow turntable (1) is equipped with a data acquisition and control module (3) and an imaging computer (4) on its exterior. The output signal of the capacitance sensor module (2) is input into the data acquisition and control module (3) and then transmitted to the imaging computer (4) for imaging after data processing. The control signal of the imaging computer (4) is input into the data acquisition and control module (3) and the data acquisition and control module (3) controls the rotation of the hollow turntable (1) and the acquisition of capacitance detection signals at the corresponding positions.

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