An Ultra-Wideband (UWB) Multi-Reference Positioning Method for In-Transformer Inspection Robots

Abstract

The present invention discloses a multi-reference positioning method for an ultra-wideband (UWB) transformer in-inspection robot, including: S100, arranging a plurality of UWB base stations near a total of 8 corners, namely, the upper 4 corners and the lower 4 corners of the target transformer; S200, dividing the transformer into a nine-square grid on the horizontal plane of the transformer; some or all of the 4 horizontal lines pass through a part of the at least 4 UWB base stations; S300, planning a cruising path of the submersible robot inside the transformer in the nine-square grid, and the cruising path is a narrow area between the transformer winding and the outer wall; S400, using the at least 4 UWB base stations and the UWB tag carried by the transformer in-inspection robot itself to achieve static positioning and dynamic positioning of the transformer in-inspection robot.

Description

Technical Field

[0001] The present invention belongs to the field of transformer underwater robots, and particularly relates to an ultra-wideband (UWB) multi-reference positioning method for an in-tank inspection robot of a transformer. Background Art

[0002] In recent years, with the rapid development of industrial technology, robots have been more and more widely used in various fields. At present, robot technology has been applied to all aspects of the power system. Using robots to replace humans for internal inspection of transformers can greatly improve the on-site work efficiency, improve the work quality, and reduce the work risk. However, the current robots used for internal inspection of oil-immersed transformers have the following problems: 1. The volume of the robot is too large, and it needs to enter through the handhole at the bottom of the bushing, which is only applicable to transformers of specific models; 2. The internal environment of the oil-immersed transformer is complex, and the precise positioning of the robot cannot be achieved. In case of robot failure, it is difficult to recover, and it is easy to cause secondary damage to the transformer.

[0003] The problem lies in that the iron shell of the oil-immersed transformer has a serious shielding effect on electromagnetic signals, and conventional positioning means cannot be applied to the internal positioning of the in-tank inspection robot in the oil-immersed transformer, resulting in the inability to directly obtain position information when the in-tank inspection robot works inside the oil-immersed transformer. Summary of the Invention

[0004] In view of this, the present invention discloses an ultra-wideband (UWB) multi-reference positioning method for an in-tank inspection robot of a transformer, including:

[0005] S100, arranging a plurality of UWB base stations near a total of 8 corners, namely the 4 upper corners and the 4 lower corners, of the target transformer;

[0006] Among them, at least 4 UWB base stations are arranged diagonally in multiple planes of the target transformer near a total of 8 corners, namely the 4 upper corners and the 4 lower corners;

[0007] S200, dividing the transformer into a nine-square grid on the horizontal plane of the transformer;

[0008] Among them, the nine-square grid includes 4 parallel horizontal lines,

[0009] Some or all of the 4 horizontal lines pass through a part of the at least 4 UWB base stations;

[0010] The nine-square grid further includes 4 parallel vertical lines,

[0011] Some or all of the 4 horizontal lines pass through the remaining part of the at least 4 UWB base stations;

[0012] S300, planning a cruising path of the underwater robot inside the transformer in the nine-square grid,

[0013] And the cruising path is the narrow area between the transformer winding and the outer wall;

[0014] S400, using the at least 4 UWB base stations and the UWB tags carried by the transformer internal inspection robot itself, to achieve static positioning and dynamic positioning of the transformer internal inspection robot.

[0015] Preferably,

[0016] Adopt diagonal arrangement or multi-base station distribution measurement.

[0017] Preferably,

[0018] 4 UWB base stations are diagonally arranged.

[0019] Preferably,

[0020] To ensure the accuracy of the UWB positioning system, the diagonal arrangement method of at least 4 base stations should be adopted.

[0021] Preferably,

[0022] If there are more than 4 base stations, the multi-base station decentralized arrangement method is adopted.

[0023] Preferably,

[0024] To solve the serious refraction of the iron core on the signal propagation, the following area division method is adopted:

[0025] The transformer is divided into 9 areas.

[0026] Preferably,

[0027] The cruising path of the submersible robot inside the transformer is the narrow area between the transformer winding and the outer wall.

[0028] Preferably,

[0029] Rely on the camera carried by the submersible robot itself to determine the distance between the submersible robot and the transformer winding and the shell.

[0030] Preferably,

[0031] After determining the distance between the submersible robot and the transformer winding and the shell, only the two-dimensional coordinates of the projection of the submersible robot on its adjacent surface need to be calculated to achieve the positioning of the submersible robot.

[0032] Preferably,

[0033] Arrange 8 base stations outside the oil tank of the transformer. When the submersible robot approaches a certain surface in the oil tank, calculate by calling the data signal on the nearest surface to eliminate the influence of the iron core and the winding on the signal propagation process, so as to improve the positioning accuracy.

[0034] In addition, the present invention also discloses a computer storage medium, wherein the storage medium includes computer instructions, which, when running on a computer, cause the computer to execute the method described in any one of the foregoing items.

[0035] Advantages of the present invention:

[0036] The present invention realizes a positioning method through UWB technology to real-time feedback and detect the position coordinates of the in-inspection robot inside the transformer for external operators to refer to, which is conducive to efficiently realizing the fault detection of oil-immersed transformers through the in-inspection robot inside the transformer. Description of the drawings

[0037] Figure 1 It is a schematic flow chart of the ultra-wideband (UWB) multi-reference positioning method of the in-inspection robot inside the transformer in an embodiment of the present invention;

[0038] Figure 2 It is a schematic diagram of the X-axis measurement coordinate in the two-dimensional positioning method in the prior art;

[0039] Figure 3 For Figure 2 It is a schematic diagram of the Y-axis measurement coordinate in the two-dimensional positioning method shown in the prior art;

[0040] Figure 4 It is a schematic diagram of the X-axis measurement coordinate in the three-dimensional positioning method in the prior art;

[0041] Figure 5 For Figure 4 It is a schematic diagram of the Y-axis measurement coordinate in the three-dimensional positioning method shown in the prior art;

[0042] Figure 6 For Figure 4 It is a schematic diagram of the Z-axis measurement coordinate in the three-dimensional positioning method shown in the prior art;

[0043] Figure 7 It is a schematic diagram of the diagonal arrangement of 4 UWB base stations in an embodiment of the present invention;

[0044] Figure 8 It is a schematic diagram of a further dispersed arrangement method of multiple UWB base stations in another embodiment of the present invention;

[0045] Figure 9 It is a schematic diagram of the cruising path of the submersible robot inside the transformer in another embodiment of the present invention. Detailed implementation manners

[0046] In order to enable those skilled in the art to understand the technical solutions disclosed by the present invention, the following will combine embodiments and relevant appendFigures 1 to 9 Describe the technical solutions of each embodiment. The described embodiments are part of the embodiments of the present invention, rather than all of them. Referring to "embodiment" in this article means that the specific features, structures, or characteristics described in combination with the embodiments can be included in at least one embodiment of the present invention. The appearance of this phrase in various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. Those skilled in the art can understand that the embodiments described herein can be combined with other embodiments.

[0047] It should be noted that the submersible robot mentioned in the present invention is a robot used for submerging in the oil tank of a transformer.

[0048] In one embodiment, referring to Figure 1 The present invention discloses a method for ultra-wideband (UWB) multi-reference positioning of an in-tank inspection robot for a transformer, and the method includes the following steps:

[0049] S100, arrange a plurality of UWB base stations near a total of 8 corners, namely the 4 upper corners and the 4 lower corners, of the target transformer.

[0050] Among them, at least 4 UWB base stations are arranged diagonally in multiple planes of the target transformer near a total of 8 corners, namely the 4 upper corners and the 4 lower corners.

[0051] S200, divide the transformer into a nine-square grid on the horizontal plane of the transformer.

[0052] Among them, the nine-square grid includes 4 parallel horizontal lines,

[0053] Some or all of the 4 horizontal lines pass through a part of the at least 4 UWB base stations;

[0054] The nine-square grid also includes 4 parallel vertical lines,

[0055] Some or all of the 4 horizontal lines pass through the remaining part of the at least 4 UWB base stations;

[0056] S300, plan the cruising path of the submersible robot inside the transformer in the nine-square grid,

[0057] and this cruising path is the narrow area between the transformer winding and the outer wall;

[0058] S400, use the at least 4 UWB base stations and the UWB tags carried by the in-tank inspection robot itself to achieve static positioning and dynamic positioning of the in-tank inspection robot for the transformer.

[0059] In another embodiment,

[0060] S100, arrange multiple UWB base stations near a total of 8 corners, namely the upper 4 corners and the lower 4 corners, of the target transformer.

[0061] Among them, at least 4 UWB base stations are arranged diagonally within multiple faces of the target transformer near a total of 8 corners, namely the upper 4 corners and the lower 4 corners.

[0062] S200, divide the transformer into a nine-square grid on the horizontal plane of the transformer.

[0063] Among them, the nine-square grid includes 4 parallel horizontal lines,

[0064] Some or all of the 4 horizontal lines pass through a part of the at least 4 UWB base stations.

[0065] The nine-square grid further includes 4 parallel vertical lines,

[0066] Some or all of the 4 horizontal lines pass through the remaining part of the at least 4 UWB base stations.

[0067] S300, plan the cruising path of the submersible robot inside the transformer within the nine-square grid,

[0068] and this cruising path is the narrow area between the transformer windings and the outer wall.

[0069] S400, use the at least 4 UWB base stations and the UWB tags carried by the internal inspection robot of the transformer itself to achieve static positioning and dynamic positioning of the internal inspection robot of the transformer.

[0070] It can be understood that planning the cruising path of the submersible robot inside the transformer within the nine-square grid includes the cruising paths at different horizontal planes of the transformer in the vertical direction, rather than just the cross-section of a fixed horizontal plane.

[0071] Regarding the prior art:

[0072] Conventional positioning means cannot be applied to the positioning of the internal inspection robot inside the oil-immersed transformer. As Figure 2 shown in the schematic diagram of a UWB two-dimensional positioning method in the prior art, the actual coordinates are (1.74, 3.42) / m. In the environment inside the transformer, the measurement error is relatively large.

[0073] The actual coordinate value measured on the X-axis is 1.74 m. As Figure 2 shown, the Y-axis has a stable range at 1.26 m, with a relatively large fluctuation amplitude. The maximum value reaches 1.80 m, and the minimum value reaches 1.05 m. It can be seen that there is a relatively large error in ordinary UWB two-dimensional positioning.

[0074] See furtherFigure 3 ,

[0075] The actual measured coordinate of the Y-axis is 3.42 m. As can be seen from the figure, the Y-axis is in a stable range within 3.51 m, with a large amplitude of up and down fluctuations. The maximum value reaches 4.03 m, and the minimum value can reach 3.01 m. The data with the measurement quantity between 200 and 350 also indicates that the deviation of the prior art from the stable value is large.

[0076] In three-dimensional positioning, the actual coordinate is (1.785, 3.46, 1.01) / m, and the actual coordinate error of the measurement robot inside the transformer is very large. Further refer to Figure 4 as shown.

[0077] The actual coordinate of the X-axis is 1.785 m, while the image stable value is about 1.67 m. There are large fluctuations up and down between each group of measurement quantities. The maximum value reaches 2.50 m, and the minimum value reaches 1.06 m. There is a large measurement error.

[0078] Further refer to Figure 5 ,

[0079] The actual coordinate of the Y-axis is 3.46 m, and the stable value is about 3.30 m. The maximum value reaches 4.12 m, and the minimum value reaches 2.51 m.

[0080] Further refer to Figure 6 , the actual coordinate of the Z-axis is 1.01 m, and the stable value is about 1 m, but there are huge fluctuations up and down.

[0081] Therefore, the above prior art precisely reflects the problems faced by conventional positioning, including conventional UWB positioning methods, in this field.

[0082] Precisely to solve the serious shielding effect of the iron shell of the oil-immersed transformer on electromagnetic signals, the present invention adopts a measurement method of diagonal arrangement or multi-base station distribution, such as Figure 7 as shown.

[0083] Figure 7 Schematically shows how 4 UWB base stations are diagonally arranged.

[0084] Refer to Figure 8 , which further schematically shows the scattered arrangement method of multiple UWB base stations. Typically, when Figure 8 the blue solid origin represents a UWB base station, this means that the above figure illustrates the case of 8 UWB base stations. To ensure the accuracy of the UWB positioning system, a diagonal arrangement method with at least 4 base stations should be adopted; if there are more than 4 base stations, a multi-base station scattered arrangement method should be adopted.

[0085] Furthermore, refer to Figure 9, to solve the serious refraction of the iron core for signal propagation, the following area division method is adopted:

[0086] The transformer is divided into 9 regions. The cruising path of the underwater robot inside the transformer is in the narrow area between the transformer winding and the outer wall. Therefore, it can determine the distance between the transformer winding and the shell by relying on the camera carried by itself, and only need to calculate the two-dimensional coordinates of the robot's projection on its approaching surface to achieve the positioning of the robot.

[0087] After the signal propagates through the iron core and the winding, the amplitude has a significant attenuation and it is difficult to judge the arrival time of the direct wave of the signal. Therefore, 8 base stations are arranged outside the oil tank of the transformer. When the underwater robot approaches a certain surface in the oil tank, it calculates by calling the data signal on the nearest surface, so as to eliminate the influence of the iron core and the winding on the signal propagation process and improve the positioning accuracy.

[0088] Furthermore, those skilled in the art know:

[0089] There is a common problem in UWB positioning. In the case of too close distance, the multipath effect will reduce the measurement accuracy. The propagation speed of the wave in oil is lower than that in air.

[0090] In another embodiment, according to the inventor's practice,

[0091] The UWB positioning technology should ensure at least a distance measurement of more than 5m in air to be accurate, while only at least 3m in oil.

[0092] This means that when arranging base stations outside the transformer oil tank, in order to reduce the influence of the multipath effect and improve the positioning accuracy, the distance between the base station and the transformer should be at least maintained at more than 3 meters, especially considering that the oil in the oil tank will slow down the signal propagation speed.

[0093] Specifically, if it is planned to arrange 8 base stations outside the transformer oil tank and hope to calculate by calling the data signal on the nearest surface when the robot approaches a certain surface to eliminate the influence of the iron core and the winding on the signal propagation process, then the distance between each base station and the transformer should be at least maintained at more than 3 meters to ensure the positioning accuracy.

[0094] In another embodiment,

[0095] Advanced signal processing algorithms are adopted to identify and suppress the multipath effect and improve the positioning accuracy.

[0096] Suppose there is a UWB positioning system with 8 base stations, and the target object is located at an unknown position P(x, y, z) in space. The positions of the base stations are respectively ;

[0097] The following are the corresponding methods for suppressing multipath effects, including the following steps:

[0098] Step 1: Signal preprocessing

[0099] Signal preprocessing may include removing noise and interference, usually implemented using filters.

[0100] Step 2: Multipath effect identification

[0101] For each base station B i , the correlation function of the signal can be calculated:

[0102]

[0103] Then find the delay time corresponding to the first peak , which represents the time of the direct signal;

[0104] where s(t) is the received signal, is its complex conjugate;

[0105] Step 3: Time difference of arrival (TDoA) estimation

[0106] Once the time of the direct signal is determined , calculate the time difference of arrival (TDoA) for subsequent positioning calculations. Assume that base station B1 is used as the reference base station, and the TDoA of other base stations relative to B1 is ,

[0107]

[0108] Step 4: Positioning calculation

[0109] Use the TDoA data to calculate the target position.

[0110] Given the TDoA values , establish the following equations to solve for the target position P(x,y,z):

[0111]

[0112] where c is the speed of light;

[0113] Among them, an exemplary solution method includes:

[0114] Construct the residual vector r;

[0115] For each base station B i , i = 2, 3,..., 8, calculate the corresponding residual:

[0116] - + ;

[0117] Calculate ;

[0118] Use a non - linear optimization method (such as gradient descent method, Newton's method, etc.) to solve for the minimum value of J.

[0119] Thus, through the above steps, the optimal position P(x, y, z) can be obtained, thereby improving the accuracy of UWB positioning.

[0120] In addition, in one embodiment, the present invention also discloses a computer storage medium, wherein the storage medium includes computer instructions that, when run on a computer, cause the computer to execute the method described in any one of the foregoing items.

[0121] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An ultra-wideband (UWB) multi-reference positioning method for a transformer internal inspection robot, comprising: S100, arranging a plurality of UWB base stations near four upper corners and four lower corners of a target transformer, a total of eight corners; S200, dividing the transformer into nine-square grids on a horizontal plane of the transformer; wherein the nine-square grid includes four parallel horizontal lines, and some or all of the four horizontal lines pass through a portion of the at least four UWB base stations; the nine-square grid also includes four parallel vertical lines, and some or all of the four horizontal lines pass through a remaining portion of the at least four UWB base stations; S300, planning a patrol path of the underwater robot inside the transformer in the nine-square grid; S400, using the at least four UWB base stations and the UWB tag carried by the transformer internal inspection robot itself, to achieve static positioning and dynamic positioning of the transformer internal inspection robot; in, Adopting a multi-base station dispersed layout method; In order to solve the serious refraction of the signal propagation by the iron core, the following area division method is adopted: Divide the transformer into 9 areas; The patrol path of the submersible robot inside the transformer is in the narrow area between the transformer winding and the outer wall; The distance between the transformer winding and the outer shell of the submersible robot is determined by the camera carried by the submersible robot itself; after the distance between the transformer winding and the outer shell of the submersible robot is determined, the positioning of the submersible robot can be realized by simply calculating the two-dimensional coordinates of the projection of the submersible robot on its approaching surface; Eight base stations are arranged outside the oil tank of the transformer. When the submersible robot approaches a certain surface in the oil tank, it uses the data signal on the surface closest to it for calculation to eliminate the influence of the core and winding on the signal propagation process and improve the accuracy of positioning. The distance between each base station and the transformer should be at least 3 meters.

2. A computer storage medium, wherein: The storage medium includes computer instructions, which, when executed on a computer, cause the computer to perform the method of claim 1 .

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