Measurement system and measurement method

Abstract

To provide a measuring system capable of more accurately measuring a liquid depth in a fluid with a simple structure.SOLUTION: The measurement system 1 includes a sensor unit 12, a housing unit 11, and a calculation unit 20. The sensor unit 12 includes a plurality of pressure detection units 15 that detect pressure. The housing unit 11 accommodates at least a part of the sensor unit 12. An arithmetic part 20 calculates the liquid depth where the sensor part 12 is positioned. The plurality of pressure detection units 15 are arranged so as to be separated from each other and exposed on the SU1 of the front face of the housing unit 11. The calculation unit 20 calculates the liquid depth based on the difference between the detection value detected by each of the plurality of pressure detection units 15 and the average of the detection values of the plurality of pressure detection units 15.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a measurement system and a measurement method. [Background technology]

[0002] There is known a measurement system that includes a pressure detector that detects the pressure of a fluid. For example, Non-Patent Document 1 discloses a measurement system that includes a plurality of pressure detectors that detect the pressure of a fluid. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] T.Kishimoto, et al. 2021. “Pitot-Static-Tube-Based Waterflow Sensor for MarineBiologging via Inside Sealing of an Incompressible Liquid” IEEE SENSORS JOURNAL,VOL. 21, NO. 18, SEPTEMBER 15, 2021. Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for easy and accurate measurement of liquid depth in a fluid. For example, when a small underwater drone is moved autonomously in the ocean, it is necessary to obtain accurate liquid depth. Liquid depth is proportional to hydrostatic pressure. For this reason, it is considered to use a pressure detection unit that detects pressure when measuring liquid depth.

[0005] However, in a fluid, the pressure detector detects the total pressure, which is the sum of the static pressure and the dynamic pressure. Because the dynamic pressure changes depending on the flow of the fluid, it is difficult for the pressure detector to detect the hydrostatic pressure. Therefore, it is difficult to accurately measure the liquid depth in a fluid.

[0006] An object of one aspect of the present invention is to provide a measurement system that can measure the depth of a liquid in a fluid more accurately while having a simple structure.An object of another aspect of the present invention is to provide a measurement method that can accurately and easily measure the depth of a liquid in a fluid. [Means for solving the problem]

[0007] A measurement system according to one aspect of the present invention comprises a sensor unit, a housing unit, and a calculation unit. The sensor unit includes a plurality of pressure detection units that detect pressure. The housing unit houses at least a portion of the sensor unit. The calculation unit calculates the liquid depth at which the sensor unit is located. The plurality of pressure detection units are arranged on the surface of the housing unit so as to be exposed and spaced apart from one another. The calculation unit calculates the liquid depth based on the difference between the detection value detected by each of the plurality of pressure detection units and the average of the detection values ​​of the plurality of pressure detection units.

[0008] A measurement method according to another aspect of the present invention includes locating a sensor unit in a fluid, acquiring a detection value detected by each of a plurality of pressure detection units that detect pressure, and calculating a liquid depth at which the sensor unit is located. The sensor unit includes a plurality of pressure detection units. The sensor unit is located in the fluid with at least a portion of the sensor unit housed in a housing unit and the plurality of pressure detection units arranged to be exposed and spaced apart from one another on the surface of the housing unit. The liquid depth is calculated based on the difference between the detection value of each of the plurality of pressure detection units and the average of the detection values ​​of the plurality of pressure detection units. [Effects of the Invention]

[0009] One aspect of the present invention provides a measurement system that can measure the depth of a liquid in a fluid more accurately despite its simple structure. Another aspect of the present invention provides a measurement method that can accurately and easily measure the depth of a liquid in a fluid. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram of a measurement system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram illustrating an example of the structure of a measuring device. [Figure 3] FIG. 10 is a diagram for explaining the direction of a fluid relative to a measuring device. [Figure 4] FIG. 2 is a diagram for explaining the relationship between pressure due to a fluid and a measurement device. [Figure 5] FIG. 2 illustrates an example of a hardware configuration. [Figure 6] 5(a) to 5(d) are diagrams illustrating an example of a method for manufacturing a measuring device. [Figure 7] 3 is a flowchart showing an example of a measurement method in the present embodiment. [Figure 8] FIG. 10 is a diagram for explaining the conditions of the simulation of the measurement device and the circulating water tank experiment. [Figure 9] 10(a) to 10(c) are diagrams for explaining the simulation conditions of the measurement device. [Figure 10] FIG. 10 is a diagram for explaining a simulation of dynamic pressure measured by the measurement device. [Figure 11] FIG. 10 is a diagram showing a simulation of the measurement results of the measurement device. [Figure 12] FIG. 10 is a diagram showing RMSE in a simulation. [Figure 13] FIG. 10 is a diagram showing detection results from a plurality of pressure detection units. [Figure 14] 10A and 10B are diagrams showing experimental results of measurements using a measurement device. [Figure 15] FIG. 10 is a graph showing RMSE from a circulating water channel experiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] [Description of the embodiments of the present disclosure]

[0012] First, embodiments of the present disclosure will be listed and described.

[0013] [1] A measurement system according to an embodiment of the present disclosure includes a sensor unit, a housing unit, and a calculation unit. The sensor unit includes a plurality of pressure detection units. The plurality of pressure detection units detect pressure. The housing unit houses at least a portion of the sensor unit. The calculation unit calculates information relating to the liquid depth at which the sensor unit is located. The plurality of pressure detection units are arranged on the surface of the housing unit so as to be exposed and spaced apart from one another. The calculation unit calculates information relating to the liquid depth based on the difference between the detection value detected by each of the plurality of pressure detection units and the average of the detection values ​​of the plurality of pressure detection units.

[0014] In the measurement system of [1] above, the sensor unit includes a plurality of pressure detection units. The plurality of pressure detection units are arranged on the surface of the housing unit so as to be exposed and spaced apart from one another. The calculation unit calculates information about the liquid depth based on the difference between the detection value detected by each of the plurality of pressure detection units and the average of the detection values ​​of the plurality of pressure detection units. In this case, the liquid depth in the fluid can be measured with a simple structure.

[0015] [2] In the measurement system of [1] above, the plurality of pressure detection units may be arranged at equal intervals along the surface of the housing unit, which makes it easier to measure the liquid depth in the fluid.

[0016] [3] In the measurement system of [1] or [2] above, the pressure detection units may be arranged at six or more locations spaced apart from one another. In this case, the accuracy of measuring the liquid depth in the fluid can be further improved.

[0017] [4] In the measurement system according to any one of [1] to [3] above, the housing may have a spherical shape, which can further improve the accuracy of measuring the liquid depth in the fluid.

[0018] [5] In any one of the measurement systems [1] to [4] above, the calculation unit calculates that the static pressure corresponding to the liquid depth in the sensor unit is "P static " and the average of the detected values ​​of multiple pressure detectors is P average", the coefficient is "α", and the detection value of each of the plurality of pressure detection units is "P i " and the number of multiple pressure detection units is "n",

number

[0019] [6] A measurement method according to another aspect of the present disclosure includes locating a sensor unit in a fluid, acquiring a detection value detected by each of a plurality of pressure detection units that detect pressure, and calculating a liquid depth at which the sensor unit is located. The sensor unit includes a plurality of pressure detection units. The sensor unit is located in the fluid with at least a portion of the sensor unit housed in a housing unit and the plurality of pressure detection units arranged to be exposed and spaced apart from each other on the surface of the housing unit. The liquid depth is calculated based on the difference between the detection value of each of the plurality of pressure detection units and the average of the detection values ​​of the plurality of pressure detection units. [Details of the embodiments of the present disclosure]

[0020] Hereinafter, an embodiment of the measurement system of the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same or corresponding parts are designated by the same reference numerals, and duplicated explanations will be omitted.

[0021] First, a schematic configuration of a measurement system according to an embodiment of the present disclosure will be described with reference to Figures 1 to 5. Figure 1 is a block diagram of the measurement system according to this embodiment. Figure 2 is a diagram showing an example of the structure of a measurement device.

[0022] The measurement system 1 measures the depth of a liquid in a fluid. For example, the measurement system 1 measures the fluid pressure in the fluid and estimates the depth of the liquid in the fluid based on the measured fluid pressure. For example, the measurement system 1 estimates the water depth in the ocean. The measurement system 1 includes, for example, a measurement device 10. For example, the measurement device 10 is placed in the ocean.

[0023] In the example shown in this embodiment, the measurement system 1 further includes a calculation unit 20 and a storage unit 30. The calculation unit 20 calculates the liquid depth in the fluid based on the signal output from the measurement device 10. The storage unit 30 stores the calculation results of the calculation unit 20. The storage unit 30 may also store the signal output from the measurement device 10.

[0024] The measuring device 10 includes a housing 11 and a sensor unit 12. The housing 11 houses at least a portion of the sensor unit 12. The housing 11 has a surface SU1 and is polyhedral or spherical. For example, the surface SU1 has a plurality of through-holes 11a that expose at least a portion of the sensor unit 12. The through-holes 11a penetrate from the surface SU1 of the housing 11 to the interior where the sensor unit 12 is housed. The through-holes 11a are spaced apart from one another. For example, the through-holes 11a are arranged at equal intervals on the surface SU1. The housing 11 has, for example, a centrosymmetric shape and is isotropic in three-dimensional space. In the example shown in this embodiment, the housing 11 is spherical, and the surface SU1 is a spherical surface. For example, the diameter of the housing 11 is approximately 50 mm. As a variation of this embodiment, the housing 11 may have a regular polyhedral shape. In this case, for example, the housing 11 may be a regular hexahedron or a polyhedron having more faces than a regular hexahedron.

[0025] 3 is a diagram for explaining the direction of the fluid relative to the measurement device. In the example shown in this embodiment, the X-axis, Y-axis, and Z-axis are shown based on the measurement device 10. The tilt with respect to the Z-axis is indicated by θ, and the tilt with respect to the Y-axis is indicated by Φ.

[0026] Figure 4 shows the pressure that the measuring device 10 receives from the fluid. In Figure 4, the surface SU1 of the housing 11 is spherical, and the fluid hits the housing 11 at an angle Φ with respect to the X axis and at a speed V. The light and dark gradation on the surface SU1 indicates the magnitude of the pressure caused by the fluid. The brighter the surface SU1, the higher the pressure caused by the fluid.

[0027] The sensor unit 12 outputs information related to the fluid pressure in the fluid. The sensor unit 12 includes a plurality of pressure detection units 15 that detect pressure. The plurality of pressure detection units 15 are arranged along the surface SU1. For example, the plurality of pressure detection units 15 are arranged so as to be spaced apart from one another and exposed on the surface SU1 of the housing unit 11. For example, the plurality of pressure detection units 15 are arranged at equal intervals along the surface SU1 of the housing unit 11. The plurality of pressure detection units 15 are arranged at six or more locations spaced apart from one another. The sensor unit 12 includes, for example, six or more pressure detection units 15. For example, as shown in FIG. 2, the sensor unit 12 includes, in addition to the plurality of pressure detection units 15, an FPC (flexible printed circuit) 42 and wiring 45. Each of the plurality of pressure detection units 15 includes, for example, an absolute pressure sensor element 41.

[0028] The FPC 42 is connected to each of the plurality of pressure detection units 15. The FPC 42 electrically connects the plurality of pressure detection units 15 to the wiring 45. The FPC 42 outputs a signal from each of the plurality of pressure detection units 15 to the wiring 45.

[0029] The FPC 42 is formed in a polyhedral or spherical shape. The FPC 42 has, for example, a regular polyhedron shape. In the example shown in this embodiment, the FPC 42 has the shape of a regular polyhedron unfolded and folded to form a regular polyhedron. In this case, the FPC 42 includes multiple surfaces SU2, each of which has a polygonal shape. For example, the multiple pressure detection units 15 are provided on different surfaces SU2. For example, the number of the multiple pressure detection units 15 is the same as the number of surfaces SU2 of the polyhedron formed by the FPC 42. For example, each pressure detection unit 15 is provided at the center of the surface SU2 when viewed from a direction perpendicular to the surface SU2. The three-dimensional shape formed by the FPC 42 and the three-dimensional shape formed by the housing unit 11 may be similar. For example, the FPC 42 has a centrosymmetric shape and is isotropic in three-dimensional space. In this specification, the shape of the FPC 42 will be described as the shape of the sensor unit 12.

[0030] The signals output from each pressure detection unit 15 are transmitted to the calculation unit 20 via the FPC 42 and the wiring 45. As a modification of the present embodiment, the signals output from each pressure detection unit 15 may be transmitted to the calculation unit 20 wirelessly instead of via the wiring 45.

[0031] The calculation result by the calculation unit 20 corresponds to the estimated value by the measurement system 1, i.e., information regarding the liquid depth at which the sensor unit 12 is located. The calculation unit 20 calculates the liquid depth at which the sensor unit 12 is located. The calculation unit 20 calculates information regarding the liquid depth at which the sensor unit 12 is located in the fluid based on the detection results of the multiple pressure detection units 15. The signal output from each pressure detection unit 15 corresponds to the detection result of that pressure detection unit 15, i.e., the detection value detected by that pressure detection unit 15. The calculation unit 20 calculates information regarding the liquid depth at which the sensor unit 12 is located in the fluid based on the difference between the detection value detected by each of the multiple pressure detection units 15 and the average of the detection values ​​of the multiple pressure detection units 15.

[0032] The calculation unit 20 includes a calculation model that outputs information about the liquid depth at which the sensor unit 12 is located in response to input of signals output from each of the multiple pressure detection units 15. This calculation model includes information indicating the relationship between the signals output from each of the multiple pressure detection units 15 and the liquid depth of the sensor unit 12. The liquid depth of the sensor unit 12 corresponds to the liquid depth of the housing unit 11, and also corresponds to the position of the measurement device 10 in the fluid.

[0033] For example, the computational model included in the computation unit 20 computes the static pressure that the fluid exerts on the measurement device 10 at the position of the sensor unit 12 based on the detection values ​​detected by each of the multiple pressure detection units 15. The static pressure is, for example, the static pressure assumed at the center of the sensor unit 12. The detection values ​​detected by each of the multiple pressure detection units 15 correspond to the total pressure. The total pressure is the sum of the dynamic pressure and the static pressure. The computation unit 20 computes the liquid depth at which the sensor unit 12 is located in the fluid based on the static pressure computed by the computational model. For example, the liquid depth is the liquid depth at the center of the sensor unit 12. As a variation of this embodiment, the computational model may compute the liquid depth at which the sensor unit 12 is located in the fluid based on the detection values ​​detected by each of the multiple pressure detection units 15.

[0034] For example, the calculation unit 20 calculates the liquid depth at which the sensor unit 12 is located in the fluid using a pressure data set detected by each of the multiple pressure detection units 15 and linear regression. For example, the calculation model included in the calculation unit 20 is a linear regression model shown in the following equation (1). This calculation model outputs information about the liquid depth at which the sensor unit 12 is located in the fluid in response to the input of a signal output from each of the multiple pressure detection units 15. The calculation unit 20 calculates the liquid depth at which the sensor unit 12 is located in the fluid by calculating the static pressure corresponding to the liquid depth of the sensor unit 12 as "P static " and the average of the detection values ​​of the plurality of pressure detection units 15 is "P average ", the coefficient is "α", and the detection value of each of the plurality of pressure detection units 15 is "P i " and the number of the pressure detection units 15 is "n", the static pressure is calculated based on the relationship shown in the following formula (1), where "α" corresponds to a regression coefficient.

number

number

number

number

[0035] Equation (2) indicates that the detection value detected by the multiple pressure detection units 15 is the sum of the static pressure and the dynamic pressure. i (φ, θ)" is a function indicating the direction of fluid flow. "ρ" is a variable indicating the density of the fluid. Equation (3) indicates that the difference between the static pressure and the average of the detection values ​​of the multiple pressure detection units 15 is related to the sum of the dynamic pressures. Equation (4) indicates that the root mean square of the difference between the detection value of each of the multiple pressure detection units 15 and the average of the detection values ​​of the multiple pressure detection units 15 is related to the dynamic pressure.

[0036] For example, the calculation unit 20 substitutes the detection value detected by each of the multiple pressure detection units 15 and the average of the detection values ​​of the multiple pressure detection units 15 into equation (1) to calculate the static pressure corresponding to the liquid depth in the sensor unit 12. The calculation unit 20 may also calculate the average of the detection values ​​of the multiple pressure detection units 15.

[0037] Next, the hardware configuration of the calculation unit 20 and the storage unit 30 will be described with reference to Fig. 5. Fig. 5 is a diagram showing an example of the hardware configuration of the calculation unit 20 and the storage unit 30.

[0038] The measurement system 1 is configured with a calculation unit 20 and a storage unit 30, each of which includes a processor 101, a main memory device 102, an auxiliary memory device 103, a communication device 104, an input device 105, and an output device 106. The calculation unit 20 and the storage unit 30 each include one or more computers configured with this hardware and software such as a program. The calculation unit 20 and the storage unit 30 may be configured with one computer or multiple computers. The calculation unit 20 and the storage unit 30 are realized in cooperation with hardware.

[0039] When the calculation unit 20 and the storage unit 30 are configured by multiple computers, these computers may be connected locally or via a communication network such as the Internet or an intranet. This connection logically constructs a single calculation unit 20 and storage unit 30.

[0040] The processor 101 executes an operating system, application programs, etc. The main memory device 102 is composed of a read-only memory (ROM) and a random-access memory (RAM). For example, at least some of the various functional units of the calculation unit 20 and the storage unit 30 can be realized by the processor 101 and the main memory device 102.

[0041] The auxiliary storage device 103 is a storage medium configured with a hard disk, a flash memory, etc. The auxiliary storage device 103 generally stores a larger amount of data than the main storage device 102. For example, at least a part of the calculation unit 20 and the storage unit 30 can be realized by the auxiliary storage device 103.

[0042] The communication device 104 is configured by a network card or a wireless communication module. For example, at least a part of the calculation unit 20 and the storage unit 30 can be realized by the communication device 104. The input device 105 is configured by an input port, a keyboard, a mouse, a touch panel, etc. For example, at least a part of the calculation unit 20 and the storage unit 30 can be realized by the input device 105. The output device 106 is configured by an output port, a display, a projection device such as a projector, etc.

[0043] The auxiliary storage device 103 stores in advance a program and data necessary for processing. This program causes the computer to execute each functional element of the calculation unit 20 and the storage unit 30. This program causes the computer to execute, for example, each process performed in a communication method described below. As the communication method, for example, the process performed in the communication system described above is performed. This program may be provided after being recorded on a tangible recording medium such as a CD-ROM, a DVD-ROM, or a semiconductor memory. This program may be provided as a data signal via a communication network.

[0044] Next, a method for manufacturing the measuring device 10 will be described with reference to Figures 6(a) to 6(d). Figures 6(a) to 6(d) are diagrams showing an example of a method for manufacturing the measuring device 10.

[0045] First, as shown in FIG. 6(a), a foldable circuit board 51 is prepared (step S1). The circuit board 51 is, for example, an origami circuit. The circuit board 51 has the shape of an unfolded polyhedron and includes a plurality of substrate pieces 52. At least two of the plurality of substrate pieces 52 are connected to each other. Each substrate piece 52 has a polygonal shape in a plan view and has one pressure detection unit 15 at the center when viewed in the thickness direction. For example, the substrate piece 52 has a pentagonal shape in a plan view.

[0046] Next, as shown in Fig. 6(b), the circuit board 51 is folded (step S2). By folding the circuit board 51, the polyhedron sensor unit 12 is formed. For example, the sensor unit 12 has a regular dodecahedron shape and includes twelve pressure detection units 15.

[0047] Next, as shown in FIG. 6(c), the sensor unit 12 is housed inside the housing unit 11 (step S3). For example, the housing unit 11 is made up of a plurality of components 53 and is formed by adhering the plurality of components 53 with an adhesive. For example, the inner surface of the housing unit 11 has a shape that is complementary to each surface SU2 of the sensor unit 12. For example, the housing unit 11 has a hollow portion formed therein that has a similar shape to the sensor unit 12. For example, the housing unit 11 includes a cylindrical portion 11b, and wiring 45 extending from the sensor unit 12 is disposed inside the cylindrical portion 11b. The wiring 45 extends from the sensor unit 12 through the inside of the cylindrical portion 11b to the outside of the housing unit 11.

[0048] Next, as shown in FIG. 6(d), resin 54 is filled into the interior of the housing 11 through the through-hole 11a of the housing 11. The resin 54 is, for example, an ultraviolet curable resin. The resin 54 is, for example, an epoxy resin. The sensor unit 12 is fixed to the housing 11 by the curing of the resin 54 inside the housing 11. In this way, the measuring device 10 is manufactured.

[0049] Next, a measurement method will be described with reference to Fig. 7. Fig. 7 is a flowchart showing an example of the measurement method.

[0050] First, the measuring device 10 is placed in a fluid (step S11). For example, in step S11, the housing 11 housing the sensor unit 12 is placed in the fluid. The housing 11 may be submerged in the fluid, or the housing 11 may be placed in advance at a position into which the fluid flows. For example, the sensor unit 12 is placed in the fluid with at least a portion of the sensor unit 12 housed in the housing 11 and with the multiple pressure detection units 15 arranged so as to be exposed and spaced apart from each other on the surface SU1 of the housing 11.

[0051] Next, signals output from the multiple pressure detection units 15 are acquired (process S12). For example, in process S12, the calculation unit 20 acquires a signal output from each of the multiple pressure detection units 15. For example, the signal output from each of the multiple pressure detection units 15 includes information indicating pressure. In other words, the detection value detected by each of the multiple pressure detection units 15 is acquired.

[0052] Next, information regarding the liquid depth at which the sensor unit 12 is located in the fluid is calculated (process S13). For example, in process S13, the calculation unit 20 calculates information regarding the liquid depth at which the sensor unit 12 is located. The calculation result by the calculation unit 20 corresponds to the liquid depth estimated by the measurement system 1. For example, the calculation unit 20 calculates the static pressure that the fluid applies to the measurement device 10 based on signals output from each of the multiple pressure detection units 15, and calculates information regarding the liquid depth at which the sensor unit 12 is located based on the calculated static pressure. In this case, a model may be used that outputs information regarding the liquid depth at which the sensor unit 12 is located in response to input of signals output from each of the multiple pressure detection units 15. The model includes linear regression shown in equation (1). For example, the calculation unit 20 calculates the liquid depth at which the sensor unit 12 is located based on signals output from each of the multiple pressure detection units 15.

[0053] Next, information relating to the liquid depth at which the sensor unit 12 is located is output (step S14). For example, in step S14, the calculation unit 20 outputs information relating to the liquid depth at which the sensor unit 12 is located as a calculation result.

[0054] Next, it is determined whether or not to end the measurement process (process S15). For example, the calculation unit 20 determines whether or not to end the measurement process. If it is determined that the measurement process should be ended (YES in process S15), the series of processes ends. If it is not determined that the measurement process should be ended (NO in process S15), the process returns to process S2.

[0055] Although an example of the measurement method has been described above, the order of the steps is not limited to this. For example, steps S12 to S15 may be repeatedly executed.

[0056] Next, the effects of the measurement system and measurement method according to the above-described embodiment will be described.

[0057] In the measurement system 1, the sensor unit 12 includes multiple pressure detection units 15. The multiple pressure detection units 15 are arranged on the surface SU1 of the housing unit 11 so as to be exposed and spaced apart from one another. The calculation unit 20 calculates information about the liquid depth based on the difference between the detection value detected by each of the multiple pressure detection units 15 and the average of the detection values ​​of the multiple pressure detection units 15. In this case, information about the liquid depth, such as static pressure, can be calculated taking into account the dynamic pressure of the fluid, which changes depending on the position of the pressure detection unit 15. In other words, information about the liquid depth of the sensor unit 12 can be calculated by correcting for errors due to the dynamic pressure of the fluid. Therefore, the liquid depth in the fluid can be measured more accurately despite the simple structure.

[0058] In the measurement system 1, the multiple pressure detection units 15 are arranged at equal intervals along the surface SU1 of the housing unit 11. In this case, the liquid depth in the fluid can be measured even more easily.

[0059] In the measurement system 1, the multiple pressure detection units 15 are arranged at six or more locations spaced apart from one another. In this case, the pressure detection units 15 can be arranged at at least two locations in each of the X-axis direction, the Y-axis direction, and the Z-axis direction. Therefore, pressure can be detected for flows in both the positive and negative directions in each of the X-axis direction, the Y-axis direction, and the Z-axis direction. In this case, the accuracy of measuring the liquid depth in the fluid can be further improved.

[0060] In the measurement system 1, the housing 11 has a spherical shape, which can further improve the accuracy of measuring the liquid depth in the fluid.

[0061] In the measurement system 1, the calculation unit 20 calculates the static pressure corresponding to the liquid depth of the sensor unit 12 as "P static ", and the average of the detection values ​​of the multiple pressure detection units 15 is P average ", the coefficient is "α", and the detection value of each of the plurality of pressure detection units 15 is "P i " and the number of the pressure detection units 15 is "n",

number

[0062] Next, verification results using the measurement system 1 will be described with reference to Figs. 8 to 15. In this verification, a simulation and a circulating water tank experiment were performed. As shown in Fig. 8, the measurement device 10 was placed in a water tank 70, and a simulation of measurement by the measurement system 1 and a circulating water tank experiment were performed in a state where a fluid 71 was flowing in a direction γ within the water tank 70. The fluid 71 was water.

[0063] 9(a) to 9(c) each show the measuring device 10 as viewed from direction γ. In FIGS. 9(a) to 9(c), the X-axis, Y-axis, and Z-axis indicate directions relative to the measuring device 10. The measuring device 10 shown in FIG. 9(b) shows the measuring device 10 shown in FIG. 9(a) rotated 90° around the Z-axis. The measuring device 10 shown in FIG. 9(c) shows the measuring device 10 shown in FIG. 9(b) rotated 90° around the Z-axis.

[0064] Fig. 10 is a diagram for explaining a simulation of dynamic pressure measured by the measurement device 10. Fig. 10 shows the detection value of dynamic pressure detected by one of the multiple pressure detection units 15 in the measurement device 10. Data D1 is a collection of detection values ​​detected by one pressure detection unit 15 when the flow rate of the fluid 71 is increased while the measurement device 10 is rotated around the Z axis.

[0065] FIG. 11 shows a simulation of the measurement results of the measurement device 10. FIG. 11 shows simulations of measurement values ​​obtained by rotating the measurement device 10 for each flow velocity at multiple flow velocities. Data D2 is a simulation of the value obtained by subtracting the average of the detection values ​​of the pressure detection unit 15 at different rotation angles from the static pressure. Data D3 is a simulation of the root mean square of the value obtained by dividing the detection value detected by the pressure detection unit 15 of the measurement device 10 by the average detection value. Data D2 and D3 are data obtained by changing the above-mentioned "φ" in 5° increments from 0° to 360° and changing the above-mentioned "θ" in 5° increments from 45° to 135°. The graph shows the variance for each flow velocity in the flow direction specified by "φ" and "θ." It was confirmed that this variance is larger as the flow velocity increases. It was confirmed that the values ​​obtained by approximating each data D2 and D3 with a quadratic function fit the square of the flow velocity.

[0066] FIG. 12 shows the RMSE (Root Mean Square Error) in the simulation. Data D4 shows the RMSE of the average of the detected values ​​of the pressure detection unit 15 at different rotation angles relative to the static pressure. Data D5 shows the RMSE of the regression model according to equation (1). As a result, it was confirmed that the regression model according to equation (1) can correct errors. In other words, the liquid depth in the fluid can be measured more accurately. It was confirmed that the liquid depth can be corrected from an error of 200 mm to an error of 7.5 mm.

[0067] FIG. 13 is a diagram showing the detection results of the multiple pressure detection units 15. FIG. 13 shows the detection values ​​detected by the multiple pressure detection units 15 at different positions in a circulating water tank experiment, for each flow velocity. Data D11 to D21 are the detection values ​​of the multiple pressure detection units 15 placed at different positions. Each plot of data D11 to D21 is the average of five pieces of data taken at different times. Data D11 to D21 change depending on the position of each pressure detection unit 15, and deviate more from static pressure as the flow velocity increases.

[0068] FIG. 14 shows the experimental results of a circulating water tank experiment using the measurement device 10. FIG. 14 shows the measurement results obtained by rotating the measurement device 10 for each flow velocity at multiple flow velocities. Data D22 is the measurement result of the value obtained by subtracting the average of the detection values ​​of the pressure detection unit 15 at different rotation angles from the static pressure. Data D23 is the measurement result of the root mean square of the detection values ​​detected by the pressure detection unit 15 of the measurement device 10. It was confirmed that the values ​​obtained by approximating each of the data D22 and D23 with a quadratic function matched the square of the flow velocity.

[0069] FIG. 15 shows the RMSE from a circulating water tank experiment. Data D24 shows the RMSE of the average of the detected values ​​of the pressure detector 15 at different rotation angles relative to the static pressure. Data D25 shows the RMSE of the regression model according to equation (1). As a result, it was confirmed that the regression model according to equation (1) can correct errors. In other words, the liquid depth in the fluid can be measured more accurately. It was confirmed that the liquid depth can be corrected from an error of 200 mm to an error of 5 mm.

[0070] The above describes embodiments and modifications of the present invention, but the present invention is not necessarily limited to the above-described embodiments and modifications, and various modifications are possible without departing from the spirit of the present invention.

[0071] For example, in the example shown in this embodiment, the calculation unit 20 and the storage unit 30 are configured separately from the measurement device 10. As a modified example, at least one of the calculation unit 20 and the storage unit 30 may be provided inside the measurement device 10. In this case, for example, at least one of the calculation unit 20 and the storage unit 30 may be housed in the housing unit 11. [Explanation of symbols]

[0072] 1...measurement system, 11...casing section, 12...sensor section, 15...pressure detection section, 20...calculation section, SU1...surface.

Claims

1. a sensor unit including a plurality of pressure detection units for detecting pressure; a housing portion that accommodates at least a portion of the sensor portion; a calculation unit that calculates information about the liquid depth at which the sensor unit is located, the plurality of pressure detection units are arranged on the surface of the housing unit so as to be exposed and spaced apart from one another; The calculation unit calculates information about the liquid depth based on the difference between the detection value detected by each of the plurality of pressure detection units and the average of the detection values ​​of the plurality of pressure detection units.

2. The measurement system according to claim 1 , wherein the plurality of pressure detection units are arranged at equal intervals along the surface of the housing unit.

3. The measurement system according to claim 1 , wherein the plurality of pressure detection units are arranged at six or more locations spaced apart from one another.

4. The measurement system according to claim 1 , wherein the housing portion has a spherical shape.

5. The calculation unit calculates the static pressure corresponding to the liquid depth in the sensor unit by calculating "P ｓｔａｔｉｃ ", and the average of the detected values ​​of the plurality of pressure detecting units is "P ａｖｅｒａｇｅ ", the coefficient is "α", and the detection value of each of the plurality of pressure detection units is "P ｉ " and the number of the pressure detection units is "n", [Equation 1] The measurement system according to claim 1 , wherein the static pressure is calculated as the information about the liquid depth based on the following relationship:

6. a sensor unit including a plurality of pressure detection units for detecting pressure, the sensor unit being at least partially housed in a housing unit, and the plurality of pressure detection units being arranged so as to be exposed and spaced apart from one another on a surface of the housing unit; and the sensor unit being positioned in a fluid. acquiring a detection value detected by each of the plurality of pressure detection units; and calculating a liquid depth at which the sensor unit is located based on a difference between the detection value of each of the plurality of pressure detection units and an average of the detection values ​​of the plurality of pressure detection units.

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