Measurement system, display method, and display program

Abstract

In the present invention, a measurement device outputs magnetic data indicating a detection result from a magnetic sensor and position data indicating a detection result from a position detection object in association with each other to a display device. The display device acquires the magnetic data and the position data from the measurement device. On the basis of the acquired position data, the display device calculates a movement path indicating change over time in the position of the measurement device. The display device displays unit magnetic information (U) indicating the strength and / or direction of a magnetic field indicated by the magnetic data at a display position corresponding to the position of the measurement device indicated by the position data within a prescribed display area (9) of a display unit. The display device displays path information (p) indicating the calculated movement path, superimposed on the unit magnetic information (U).

Description

Measurement system, display method, and display program

[0001] The present invention relates to a measurement system, a display method, and a display program for displaying the results of measurement by a magnetic sensor.

[0002] Devices for measuring magnetic fields in space are known. Patent Document 1 discloses a magnetic measurement system equipped with a magnetic sensor, an acceleration sensor, and an angular velocity sensor. In the magnetic measurement system, the magnetic detector calculates changes in the magnetic field generated by a magnetic body as magnetic data based on detection signals from the magnetic sensor. The magnetic detector also calculates position data indicating the position of the magnetic sensor based on the detection signals from the acceleration sensor and the angular velocity sensor. The magnetic detector associates the calculated magnetic data with position data and transmits the data to a data processing device. The data processing device displays a magnetic distribution map on a display unit, showing the magnitude of the magnetic data corresponding to the positions indicated by the respective position data.

[0003] JP 2016-130711 A

[0004] To measure an entire area using a magnetic sensor and display a magnetic distribution map on the display, the user must bring the magnetic sensor close to every location in the area to obtain magnetic data. However, while the magnetic sensor is measuring, the user cannot recognize which location in the area the magnetic sensor is close to. This poses a problem in that the user cannot easily obtain a magnetic distribution map that covers the entire area.

[0005] An object of the present invention is to provide a measurement system, a display method, and a display program that are capable of measuring an entire area using a magnetic sensor and displaying the measurement results.

[0006] A measurement system according to a first aspect of the present invention is a measurement system comprising: a measurement device having a magnetic sensor capable of detecting a magnetic field and a position detector capable of detecting a position; and a display device that acquires the detection results of the magnetic sensor and the position detector from the measurement device and displays them on a display unit, wherein the measurement device comprises an output means that associates magnetic data indicating the detection results of the magnetic sensor with position data indicating the detection results of the position detector and outputs them to the display device, and the display device comprises an acquisition means that acquires the magnetic data and the position data from the measurement device; a calculation means that calculates a movement trajectory that indicates changes in the position of the measurement device over time based on the position data acquired by the acquisition means; a first display means that displays magnetic information indicating at least one of the strength and direction of the magnetic field indicated by the magnetic data acquired by the acquisition means at a display position within a predetermined display area of ​​the display unit that corresponds to the position of the measurement device indicated by the position data acquired by the acquisition means; and a second display means that displays trajectory information that indicates the movement trajectory calculated by the calculation means.

[0007] The measurement system displays magnetic information indicating the detection results of the magnetic sensor and trajectory information based on the detection results of the position detector on the display unit. By referring to the trajectory information, the user can easily identify areas where measurement by the measurement device is not being performed. In this case, the user can perform measurement by the measurement device without omission within the area by bringing the measurement device closer to the area where measurement by the measurement device is not being performed. Therefore, the user can display a magnetic distribution map on the display unit, with magnetic information displayed across the entire display area.

[0008] In a first aspect, the display area may indicate a target area, which is an area of ​​space to be detected by the measurement device, and the first display means may display the magnetic information as the measurement device moves within the target area, and the second display means may display the trajectory information as the measurement device moves within the target area. In this case, a user can recognize an area to which the measurement device is not close during the course of moving the measurement device within the target area, and can bring the measurement device close to this area to perform measurement.

[0009] In the first aspect, the second display means may display the trajectory information superimposed on the magnetic information displayed by the first display means, so that the user can check the magnetic information while understanding the area to which the measuring device is not approaching from the trajectory information.

[0010] In the first aspect, the device may further include a third display means for displaying statistical information calculated based on the magnetic information in a portion of the display area where the magnetic information is not displayed. In this case, a user can infer, based on the statistical information, the magnetic information in a portion of the display area corresponding to an area where the measuring device is not located.

[0011] In the first aspect, the statistical information may represent an average value of the magnetic information, in which case a user can accurately estimate the magnetic information of a portion of the display area corresponding to an area to which the measuring device is not brought, based on the average value represented by the statistical information.

[0012] In the first aspect, the display device may further include a switching unit that switches between a state in which the magnetic information is displayed by the first display unit and a state in which the trajectory information is displayed by the second display unit, allowing a user to recognize the magnetic information and the trajectory information separately.

[0013] In a first aspect, the measurement device may include a plurality of the magnetic sensors, each of which includes a gradiometer, and the hysteresis amount may be defined as the absolute value of a ratio of the maximum difference between the detection results in the direction of increasing and decreasing magnetic field strength, where the hysteresis amount is defined as the denominator of the change in magnetic field strength and the numerator of the maximum difference between the detection results in the direction of increasing and decreasing magnetic field strength, and the hysteresis amount of each of the plurality of magnetic sensors may be 0.5% or less. In this case, the measurement device can accurately measure the first derivative of the magnetic field.

[0014] A display method according to a second aspect of the present invention includes an acquisition step of acquiring, from a measurement device having a magnetic sensor capable of detecting a magnetic field and a position detector capable of detecting a position, magnetic data indicating the detection results of the magnetic sensor and position data indicating the detection results of the position detector, a calculation step of calculating a movement trajectory indicating a change in the position of the measurement device over time based on the position data acquired in the acquisition step, a first display step of displaying magnetic information indicating at least one of the strength and direction of the magnetic field indicated by the magnetic data acquired in the acquisition step in a display position within a predetermined display area of ​​a display unit corresponding to the position of the measurement device indicated by the position data acquired in the acquisition step, and a second display step of displaying trajectory information indicating the movement trajectory calculated in the calculation step.The second aspect achieves the same effects as the first aspect.

[0015] A display program according to a third aspect of the present invention causes a computer to execute the following steps: acquiring, from a measurement device having a magnetic sensor capable of detecting a magnetic field and a position detector capable of detecting a position, magnetic data indicating the detection results of the magnetic sensor and position data indicating the detection results of the position detector; calculating, based on the position data acquired in the acquiring step, a movement trajectory indicating a change in the position of the measurement device over time; a first display step displaying, in a predetermined display area of ​​a display unit, magnetic information indicating at least one of the strength and direction of the magnetic field indicated by the magnetic data acquired in the acquiring step at a display position corresponding to the position of the measurement device indicated by the position data acquired in the acquiring step; and a second display step displaying trajectory information indicating the movement trajectory calculated in the calculating step. The third aspect achieves the same effects as the first aspect.

[0016] 1 is a diagram showing an overview of the measurement system 1. FIG. 1 is a front view of the measurement device 2. FIG. 2 is a cross-sectional view showing the internal structure of the measurement device 2. FIG. 3 is a plan view showing the internal structure of the measurement device 2. FIG. 4 is a block diagram showing the electrical configuration of the measurement device 2 and the tablet terminal 3. FIG. 5 is a diagram showing display screens 51 to 56. FIG. 6 is a diagram showing display screens 61 to 64. FIG. 7 is a diagram showing display screens 71 to 74. FIG. 8 is a flowchart showing measurement device processing. FIG. 9 is a flowchart showing tablet terminal processing. FIG. 10 is a flowchart showing tablet terminal processing, which is a continuation of FIG. 10. FIG. 11 is a diagram showing display screens 91 and 92.

[0017] A measurement system 1 according to one embodiment of the present invention will be described below with reference to the drawings. The drawings are used to explain technical features that can be adopted by the present invention. The configuration of the device described is not intended to be limiting, but is merely an illustrative example.

[0018] <Overview of Measurement System 1> The measurement system 1 will be described with reference to FIG. 1 . The measurement system 1 includes a measurement device 2 and a tablet terminal 3. The measurement device 2 detects the strength and direction of nearby magnetic fields and the position of the measurement device 2. The measurement device 2 is held by a user. For example, the user repeatedly moves the measurement device 2 horizontally within a predetermined region R where magnetic field measurement is desired, while gradually shifting the position vertically (arrow Y). The measurement device 2 transmits data indicating detection results detected while moving within the predetermined region R to the tablet terminal 3. Based on the data received from the measurement device 2, the tablet terminal 3 displays a display screen IM indicating the magnetic distribution within the predetermined region R on the display 34.

[0019] The measurement system 1 can be used for (1) detecting minute magnetic sources, (2) detecting steel weapons, and (3) visualizing spatial magnetic distribution. Specific application examples of (1) to (3) are as follows: (1) Detection of minute magnetic sources (1-1) Searching for lost surgical needles inside a patient's body or throughout an operating room (1-2) Identifying the location of sentinel lymph nodes that trap nanomagnetic particles during breast cancer metastasis testing (1-3) Possession inspection of electronic components such as small data storage devices in entrance / exit security systems, etc. (2) Detection of steel weapons (2-1) Estimation of the shape and size of weapons based on the estimated positions of the north and south poles of magnetic objects (3) Visualization of spatial magnetic distribution (3-1) Visualization of the arrangement of structural members within walls during interior construction work on houses (3-2) Non-destructive testing of cracks in structural members during the process of diagnosing deterioration of steel frames, reinforcing bars, etc. (3-3) Buried structures, ruins, and geological surveys Note that the uses of the measurement system 1 are not limited to the above specific examples.

[0020] <Measuring device 2> An overview of the measuring device 2 will be described with reference to Figures 2 to 4. The upper, lower, left, and right sides in Figure 2 correspond to the upper, lower, left, and right sides of the measuring device 2, respectively. The upper, lower, left, and right sides in Figure 4 correspond to the rear, front, left, and right sides of the measuring device 2, respectively.

[0021] As shown in FIG. 2 , the measurement device 2 has a housing 11. The housing 11 has a generally oval shape elongated in the left-right direction when viewed from the front. The housing 11 has an upper wall 11U, a lower wall 11B, a front wall 11F, and a rear wall 11S (see FIGS. 3 and 4 ). The upper wall 11U is curved convexly upward. The lower wall 11B is curved convexly downward. The upper wall 11U and the lower wall 11B are connected at both ends in the left-right direction. The front wall 11F closes the front ends of the upper wall 11U and the lower wall 11B. As shown in FIGS. 3 and 4 , the rear wall 11S closes the rear ends of the upper wall 11U and the lower wall 11B. As shown in FIG. 4 , the front wall 11F and the rear wall 11S each have a flat plate shape and are perpendicular to the front-to-rear direction.

[0022] 2, the upper wall 11U is provided with a push button 25. The push button 25 is pressed by the user when measurement is to be performed by the measurement device 2.

[0023] As shown in Fig. 3, through-holes 17H, 18H, 19H, and 20H are provided in the rear wall 11S. As shown in Fig. 4, a power jack 17 for connecting an AC adapter is disposed inside the through-hole 17H. When the power jack 17 is connected to the AC adapter, power is supplied to and charged by a rechargeable battery (not shown) mounted in the housing 11. LEDs 27A and 27B are disposed inside the through-holes 18H and 19H, respectively. A USB (registered trademark) jack 20 is provided inside the through-hole 20H. In this embodiment, a Wi-Fi dongle for Wi-Fi communication with the tablet terminal 3 is connected to the USB jack 20.

[0024] As shown in Figure 3, a support plate 16L extends rightward from the left end of the bottom wall 11B. A support plate 16R extends leftward from the right end of the bottom wall 11B. The support plates 16L and 16R support the board 16. In Figure 4, the support plates 16L and 16R are omitted. As shown in Figures 3 and 4, the board 16 is disposed in the vertical center of the space inside the housing 11. The board 12 is perpendicular to the vertical direction. A control unit 2A (see Figure 5), which will be described later, and other components are mounted on the board 12.

[0025] As shown in Figures 3 and 4, magnetic sensors 23A and 23B are provided near the left end of the bottom wall 11B. Each of the magnetic sensors 23A and 23B is an MR sensor capable of measuring the strength and direction of a magnetic field in each of three axial directions. The magnetic sensors 23A and 23B have the same specifications. The magnetic sensors 23A and 23B are arranged in the left-right direction along the inner wall surface of the bottom wall 11B.

[0026] 3, a motion sensor 24 is provided on the upper surface of the support plate 16L above the magnetic sensor 23B in the vertical direction. The motion sensor 24 is a six-axis sensor that can measure the position of the measurement device 2 by detecting acceleration in three axial directions and angular velocity in three axial directions.

[0027] <Electrical Configuration> The electrical configuration of the measurement device 2 will be described with reference to FIG. 5 . The measurement device 2 includes a CPU 21, a memory 22, magnetic sensors 23A and 23B, a motion sensor 24, a push button 25, LEDs 27A and 27B, and a communication interface (I / F) 28. The CPU 21 controls the entire measurement device 2. The memory 22 includes a volatile memory element and a non-volatile memory element. The memory 22 stores at least the programs executed by the CPU 21 and various setting information. The communication I / F 28 is an interface element that controls communication with devices connected to the USB jack 20 (see FIG. 4 ). For example, the communication I / F 28 performs Wi-Fi communication via a Wi-Fi dongle connected to the USB jack 20. The memory 22, the magnetic sensors 23A and 23B, the motion sensor 24, the push button 25, the LEDs 27A and 27B, and the communication I / F 28 are electrically connected to the CPU 21 via a bus. The CPU 21 and the memory 22 are also referred to as a "control unit 2A."

[0028] The CPU 21, memory 22, magnetic sensors 23A and 23B, motion sensor 24, LEDs 27A and 27B, and communication I / F 28 are driven by power supplied from a rechargeable battery (not shown).

[0029] The electrical configuration of the tablet terminal 3 will be described with reference to FIG. 5 . The tablet terminal 3 has a CPU 31, a memory 32, a display 34, a touch panel 35, and a communication I / F 36. The CPU 31 controls the entire tablet terminal 3. The memory 32 includes a volatile memory element and a non-volatile memory element. The memory 32 stores at least the programs executed by the CPU 31 and various setting information. The communication I / F 36 is an interface element for performing Wi-Fi communication. The memory 32, the display 34, the touch panel 35, and the communication I / F 36 are electrically connected to the CPU 31 via a bus. The CPU 31 and the memory 32 are also referred to as a "control unit 3A."

[0030] The program stored in the memory 32 of the tablet terminal 3 may be downloadable from an external server via the communication I / F 36. The CPU 31 of the tablet terminal 3 may also read the program from a storage medium and store it in the memory 32.

[0031] <Display Screen> Specific examples of the display screen IM displayed on the display 34 of the tablet terminal 5 (display screens 51 to 56 (see FIG. 6), display screens 61 to 64 (see FIG. 7), and display screens 71 to 74 (see FIG. 8)) will be described with reference to FIGS. 6 to 8. The display screen IM shows the two-dimensional spatial distribution of the magnetic field strength measured by the measurement device 2. A display area 9 on the display screen IM, surrounded by a frame 90, shows the area of ​​space that is the target of measurement by the measurement device 2 (hereinafter referred to as the "target area"). The target area corresponds to a predetermined area R (see FIG. 1) where the user desires to measure the magnetic field.

[0032] 6, the display screen 51 shows a state before measurement is started by the measurement device 2. On the display screen 51, nothing is displayed in the display area 9.

[0033] Here, for example, suppose that a user performs an operation of moving the measuring device 2 horizontally once within the predetermined region R while pressing the push button 25 (see FIG. 2 ) of the measuring device 2. Hereinafter, this operation of the measuring device 2 is referred to as a “scanning operation.” Display screen 52 indicates the display screen displayed on the display 34 midway through the first scanning operation. Display screen 53 indicates the display screen displayed on the display 34 at the end of the first scanning operation. As described above, on the display screens 52 and 53, a plurality of square units of magnetic information U, each indicating the magnetic field strength with a color, are displayed in portions of the display area 9 corresponding to positions through which the measuring device 2 has passed within the predetermined region R. In addition, trajectory information p, which indicates the movement trajectory of the measuring device 2 with an arrow, is displayed superimposed on the units of magnetic information U. Hereinafter, a plurality of units of magnetic information U displayed in response to one scanning operation will be referred to as “scanned magnetic information M.” The scanned magnetic information M displayed in response to the nth scanning operation will be referred to as the “nth scanned magnetic information M(n).” The units of magnetic information U and scanned magnetic information M will be collectively referred to as “magnetic information m.”

[0034] Next, for example, if the user, after completing the first scanning operation, performs a second scanning operation at a position adjacent to and below the position of the first scanning operation, a display screen 54 is displayed on the display 34 at the end of the second scanning operation. The display screen 54 includes the first scanning magnetic information M(1) and the second scanning magnetic information M(2), as well as trajectory information p superimposed on each of the first scanning magnetic information M(1) and the second scanning magnetic information M(2). Furthermore, for example, if the user, after completing the second scanning operation, performs a third scanning operation at a position adjacent to and below the position of the second scanning operation, a display screen 55 is displayed on the display 34 at a point in the middle of the third scanning operation. In addition to the display screen 54, the display screen 55 includes a plurality of unit magnetic information U corresponding to the third scanning operation and trajectory information p superimposed on the plurality of unit magnetic information U.

[0035] Next, consider a case where, after completing the third scanning operation, the user performs a fourth scanning operation at a position below the position of the third scanning operation. In this case, at the end of the fourth scanning operation, a display screen 56 is displayed on the display 34. On the display screen 56, a portion of the third scanning magnetic information M(3) and the fourth scanning magnetic information M(4) is missing magnetic information m. In this case, the display screen 56 switches to a display screen 61 shown in FIG. 7 . The display screen 61 differs from the display screen 56 in that statistical information S(1) is displayed in the portion between the third scanning magnetic information M(3) and the fourth scanning magnetic information M(4). The color of the statistical information S(1) indicates the average value of the magnetic field strengths represented by the multiple unit magnetic information U included in the adjacent third scanning magnetic information M(3) and fourth scanning magnetic information M(4).

[0036] Similarly, consider a case where, after completing the fourth scanning operation, the user performs a fifth scanning operation at a position below the position of the fourth scanning operation. In this case, a display screen 62 is displayed on the display 34. On the display screen 62, statistical information S(2) is displayed in the portion between the fourth scanning magnetic information M(4) and the fifth scanning magnetic information M(5). The color of the statistical information S(2) indicates the average value obtained by averaging the magnetic field strengths indicated by the multiple unit magnetic information U contained in the adjacent fourth scanning magnetic information M(4) and fifth scanning magnetic information M(5).

[0037] Next, consider a case where, after completing the fifth scanning operation, the user performs a sixth scanning operation at a position between the positions of the third and fourth scanning operations. In this case, at the end of the sixth scanning operation, display screen 63 is displayed on display 34. On display screen 63, sixth scanning magnetic information M(6) is displayed in place of statistical information S(1) that was displayed on display screens 61 and 62. Similarly, if the user performs a scanning operation at a position between the positions of the fourth and fifth scanning operations, scanning magnetic information M is displayed in place of statistical information S(2) at the position of statistical information S(2).

[0038] In addition, for example, if the user repeats a scanning operation at the same position where a scanning operation has already been performed, the scanning magnetic information M already displayed in the display area 9 of the display screen IM is replaced with the scanning magnetic information M corresponding to the latest scanning operation.

[0039] Take the example of a case where the user repeatedly performs a scanning operation, moving the measuring device 2 so that it approaches all parts of the predetermined region R at least once. In this case, a display screen 64 is displayed on the display 34. On the display screen 64, all parts of the display region 9 surrounded by a frame line 90 are occupied by multiple pieces of scanned magnetic information M. In addition, trajectory information p indicating the movement trajectory of the measuring device 2 is displayed superimposed on each of the multiple pieces of scanned magnetic information M.

[0040] The user can also switch the display image displayed on the display 34. As shown in FIG. 8 , the display screen 71, which displays the magnetic information m and the trajectory information p, is switched to a display screen 72 or a display screen 73 by the user operating the touch panel 35. In the display screen 72, the display area 9 within the frame 90 contains only the magnetic information m, and does not contain the trajectory information p. In other words, the display mode of the display screen 72 is the same as that of the display screen 71, except that the trajectory information p has been deleted. The user can also switch the display screen 72 to a display screen 74. The display screen 74 is obtained by filtering the magnetic field strength indicated by each of the multiple unit magnetic information U included in the display screen 72. In the display screen 74, the sharp changes in magnetic field strength at the boundaries between the unit magnetic information U are alleviated.

[0041] On the display screen 73, only the trajectory information p is included in the display area 9 within the frame 90, and the magnetic information m is not included. In other words, the display form of the display screen 73 is the same as that of the display screen 71, except that the magnetic information m is deleted.

[0042] 9, a description will be given of measurement device processing executed by the CPU 21 of the measurement device 2. When a power button (not shown) is pressed to turn on the power, the CPU 21 starts measurement device processing by reading and executing a program stored in the memory 22.

[0043] The CPU 21 determines whether the operation of pressing the push button 25 has been detected (S11). If the CPU 21 determines that the operation of pressing the push button 25 has not been detected (S11: NO), the process returns to S11. In this state, for example, assume that a user starts a scanning operation of the measurement device 2 within a predetermined region R (see FIG. 1) while pressing the push button 25 of the measurement device 2. The CPU 21 determines that the operation of pressing the push button 25 has been detected (S11: YES). The CPU 21 initializes the coordinate system so that the spatial coordinate data indicating the current position of the measurement device 2 becomes the origin (S13). The CPU 21 sets the variable i to 1 (S15).

[0044] The CPU 21 receives signals (hereinafter referred to as "magnetic signals") output from each of the magnetic sensors 23A and 23B (S17). Based on the received magnetic signals, the CPU 21 determines the strength of the magnetic field measured by each of the magnetic sensors 25A and 25B (S19). The CPU 21 further calculates the average value of the strength of the magnetic field measured by each of the magnetic sensors 25A and 25B (S19). The CPU 21 also receives a signal (hereinafter referred to as "position signal") output from the motion sensor 24 (S21). Based on the received position signal, the CPU 21 determines coordinates indicating the position of the motion sensor 24 (S23). The CPU 21 determines the coordinates based on the origin based on the coordinate system initialized in the process of S13. The CPU 21 associates the magnetic data indicating the average value of the magnetic field strength calculated in the process of S19 with the position data indicating the coordinates determined in the process of S21, and assigns a variable i as an index. The CPU 21 stores the indexed magnetic data and position data in the memory 22 (S25).

[0045] The CPU 21 determines whether the processes of S17 to S25 have been executed continuously for 1 second or more (S27). If the CPU 21 determines that the processes of S17 to S25 have not been executed continuously for 1 second or more (S27: NO), it waits for 10 ms (S29) and updates the variable i by adding 1 (S31). The CPU 21 returns the process to S17 and repeats the processes of S17 to S25. As a result, the CPU 21 repeatedly executes the processes of S17 to S25 for 1 second at 10 ms intervals. If the CPU 21 determines that the processes of S17 to S25 have been executed continuously for 1 second or more (S27: YES), it proceeds to S33. The CPU 21 transmits the magnetic data and position data, which have been assigned indexes and associated with each other, to the tablet terminal 5 via Wi-Fi communication (S33).

[0046] The CPU 21 determines whether the operation of pressing the push button 25 has been released (S35). If the CPU 21 determines that the operation of pressing the push button 25 has not been released (S35: NO), it updates the variable i by adding 1 (S37). The CPU 21 returns the process to S17 and repeats the processes of S17 to S35. If the CPU 21 determines that the operation of pressing the push button 25 has been released (S35: YES) and if it determines that the push button 25 has been pressed again within 10 seconds thereafter (S39: YES), it returns the process to S15. In this case, the CPU 21 sets the variable i to 1 (S15) and repeats the processes of S17 to S35.

[0047] As a result, if the push button 25 is continuously pressed (S35: NO), the CPU 21 associates the magnetic data and position data with each other and stores them in the memory 22 at 10 ms intervals, and transmits them to the tablet terminal 5 every 1 s. The magnetic data and position data transmitted in this case are assigned indexes of 1, 2, 3, etc. Furthermore, if the push button 25 is released once and then pressed again immediately (S39: YES), the CPU 21 associates the magnetic data and position data with each other and stores them in the memory 22 at 10 ms intervals, and transmits them to the tablet terminal 5 every 1 s. The magnetic data and position data transmitted in this case are assigned indexes of 1, 2, 3, etc. In other words, the indexes assigned to the magnetic data and position data are initialized when the push button 25 is released once.

[0048] For example, the user performs a first scanning operation while pressing the push button 25 of the measuring device 2, then releases the push button 25 of the measuring device 2, moves the measuring device 2 to the position for the next scanning operation, and presses the push button 25 again to perform a second scanning operation. The user repeats the scanning operation until the measuring device 2 approaches all parts within the predetermined region R. In this case, the CPU 21 repeats the processes of S15 to S39 for each scanning operation performed by the user. As a result, the magnetic data and position data, each indexed 1, 2, 3, ..., are continuously transmitted from the measuring device 2 to the tablet terminal 3 for each scanning operation.

[0049] For example, suppose the user repeatedly performs a scanning operation and brings the measurement device 2 close to all parts within the predetermined region R. In this case, the user releases the push button 25 to end measurement by the measurement device 2. The CPU 21 determines that the operation of pressing the push button 25 has been released (S35: YES) and that the push button 25 has not been pressed again within 10 seconds thereafter (S39: NO). In this case, the CPU 21 returns the process to S11.

[0050] 10 and 11, a description will be given of the tablet terminal processing executed by the CPU 31 of the tablet terminal 3. When the CPU 31 detects, via the touch panel 35, an instruction to notify that measurement by the measurement device 2 has started, the CPU 31 starts the tablet terminal processing by reading and executing a program stored in the memory 32.

[0051] 10 , the CPU 31 displays a frame 90 of the display screen IM on the display 34 (S51). The CPU 31 determines whether the magnetic data and position data transmitted from the measurement device 2 have been received via Wi-Fi communication (S53). If the CPU 31 determines that the magnetic data and position data have not been received (S53: NO), the process returns to S53. If the CPU 31 determines that the magnetic data and position data transmitted from the measurement device 2 have been received (S53: YES), the CPU 31 stores the received magnetic data and position data in the memory 32 (S55).

[0052] The CPU 31 determines whether a predetermined number of pieces of magnetic data and position data have been received and stored in the memory 32 (S57). If the number of received magnetic data and position data is less than the predetermined number (S57: NO), the CPU 31 returns the process to S53. The CPU 31 repeats the processes of S53 and S55 until the predetermined number of pieces of magnetic data and position data have been received. If the CPU 31 determines that the predetermined number of pieces of magnetic data and position data have been received and stored in the memory 32 (S57: YES), the process proceeds to S59.

[0053] The CPU 31 identifies the magnetic field strength indicated by each of the predetermined number of magnetic data stored in the memory 32 (S59). The CPU 31 further calculates the average value of the identified magnetic field strengths (S61). Next, the CPU 31 identifies the coordinates indicated by each of the predetermined number of position data stored in the memory 32 (S63). The CPU 31 further calculates the average of the identified coordinates (S65). The calculated average value of the magnetic field strength is used to identify the color of the unit magnetic information U to be displayed on the display screen IM. The calculated average value of the coordinates is also used to identify the position of the unit magnetic information U to be displayed on the display screen IM.

[0054] The CPU 31 determines whether the magnetic data and position data assigned with index "1" are included among the predetermined number of magnetic data and position data stored in the memory 32 (S67). If the CPU 31 determines that the magnetic data and position data assigned with index "1" are included (S67: YES), it identifies, by coordinate transformation, a position in the display area 9 of the display screen IM corresponding to the average value of the coordinates calculated by the processing of S65. The CPU 31 stores the identified position in the memory 32 as the coordinates of the starting point of the trajectory information p indicated by the arrow (hereinafter referred to as "starting point coordinates") (S69). The CPU 31 proceeds to S71. On the other hand, if the CPU 31 determines that the magnetic data and position data assigned with index "1" are not included (S67: NO), it proceeds to S71.

[0055] The CPU 31 identifies, by coordinate conversion, a position (hereinafter referred to as the "display position") in the display area 9 of the display screen IM that corresponds to the average value of the coordinates calculated by the processing of S65. The CPU 21 identifies a color that corresponds to the average magnetic field strength calculated by the processing of S61. The CPU 21 displays the unit magnetic information U indicated in the identified color at the identified display position in the display area 9 of the display screen IM (S71).

[0056] The CPU 31 reads out and acquires the starting point coordinates stored in the process of S69 from the memory 32. The CPU 31 calculates a path from the position indicated by the read starting point coordinates to the display position calculated in the process of S65 as a movement trajectory indicating the change in the position of the measurement device 2 over time (S73). The CPU 31 displays trajectory information p indicating the movement trajectory calculated in the process of S73 by superimposing it on the unit magnetic information U displayed at the display position in the process of S71 (S75. Note that the trajectory information p is indicated by an arrow extending from the position indicated by the starting point coordinates toward the display position specified in the process of S65.

[0057] 11 , the CPU 31 determines whether there is a portion adjacent to and sandwiched between the unit magnetic information U (hereinafter referred to as a "statistics display portion") within the portion of the display area 9 of the display screen IM where no unit magnetic information U is displayed (S81). If the CPU 31 determines that there is a statistics display portion (S81: YES), the process proceeds to S83. The CPU 31 calculates the average value of the magnetic field strength indicated by the unit magnetic information U displayed adjacent to the statistics display portion (S83). The CPU 31 displays statistical information S, which indicates the calculated average magnetic field strength using color, in the statistics display portion (S87). The CPU 31 proceeds to S89. On the other hand, if the CPU 31 determines that there is no statistics display portion within the display area 9 of the display screen IM (S81: NO), the process proceeds to S89.

[0058] The CPU 31 determines whether an instruction to end measurement by the measurement device 2 has been detected via the touch panel 35 (S89). If the CPU 31 determines that an instruction to end measurement has not been detected (S89: NO), the process proceeds to S103. If the CPU 31 determines that an instruction to end measurement has been detected (S89: YES), the process proceeds to S91.

[0059] The CPU 31 determines whether an operation for switching to a display mode in which only the magnetic information m is displayed on the display screen IM (hereinafter referred to as the "magnetic display mode") has been detected via the touch panel 35 (S91). If the CPU 31 determines that an operation for switching to the magnetic display mode has been detected (S91: YES), the CPU 31 displays only the magnetic information m in the display area 9 of the display screen IM (S93). The CPU 31 does not display the trajectory information p in the display area 9. The CPU 31 proceeds to S103.

[0060] The CPU 31 determines whether an operation for switching to a display mode in which only the trajectory information p is displayed on the display screen IM (hereinafter referred to as the "trajectory display mode") has been detected via the touch panel 35 (S91: NO, S95). If the CPU 31 determines that an operation for switching to the trajectory display mode has been detected (S95: YES), the CPU 31 displays only the trajectory information p in the display area 9 of the display screen IM (S97). The CPU 31 does not display the magnetic information m in the display area 9. The CPU 31 proceeds to S103.

[0061] The CPU 31 determines whether an operation for switching to a display mode in which both the magnetic information m and the trajectory information p are displayed on the display screen (hereinafter referred to as the "simultaneous display mode") has been detected via the touch panel 35 (S95: NO, S99). If the CPU 31 determines that an operation for switching to the simultaneous display mode has been detected (S99: YES), the CPU 31 displays both the magnetic information m and the trajectory information p in the display area 9 of the display screen IM (S101). The CPU 31 proceeds to S103.

[0062] If the CPU 31 does not detect an operation to switch the display mode (NO at step S99), the process proceeds to step S103.

[0063] The CPU 31 determines whether an instruction to end the display of the display screen IM on the display 34 has been detected via the touch panel 35 (S103). If the CPU 31 determines that an instruction to end the display of the display screen IM has been detected (S103: YES), the CPU 31 ends the tablet terminal processing. On the other hand, if the CPU 31 determines that an instruction to end the display of the display screen IM has not been detected (S103: NO), the processing returns to S53 (see FIG. 10).

[0064] <Actions and Effects of the Present Embodiment> In the measurement system 1, the tablet terminal 3 displays, on the display 34, magnetic information m based on the detection results of the magnetic sensors 23A and 23B of the measurement device 2, and trajectory information p based on the detection results of the motion sensor 24 of the measurement device 2. By referring to the trajectory information p, the user can easily recognize the parts of the desired predetermined region R to which the measurement device 2 is not approaching. In this case, the user can measure the entire predetermined region R with the measurement device 2 by moving the measurement device 2 to the parts of the predetermined region R to which the measurement device 2 is not approaching. Therefore, the user can display, on the display 34, a magnetic distribution map in which the magnetic information m is displayed in the entire display region 9 of the display screen IM.

[0065] While the user is measuring the predetermined region R with the measuring device 2, the measurement system 1 displays magnetic information m and trajectory information p in a display position in the display area 9 corresponding to the portion of the predetermined region R to which the measuring device 2 has approached. In this case, before the measurement of the predetermined region R by the measuring device 2 is completed, the user can recognize the portion of the predetermined region R to which the measuring device 2 has not approached, and can perform an operation to bring the measuring device 2 closer to this portion.

[0066] On the display screen IM, an arrow shown as the trajectory information p is displayed superimposed on the magnetic information m (unit magnetic information U, scanned magnetic information M). In this case, the user can intuitively associate and recognize the magnetic information m with the trajectory information p. Therefore, the user can check the magnetic field strength of the portion of the predetermined region R to which the measuring device 2 has approached using the magnetic information m, while easily understanding the portion to which the measuring device 2 has not approached using the trajectory information p.

[0067] Statistical information S is displayed in the display area 9 of the display screen IM in a portion where magnetic information m is not displayed. The color displayed as statistical information S indicates the average value of the magnetic strength indicated by the adjacent magnetic information m. In this case, the user can accurately estimate the magnetic field strength in the portion of the predetermined region R to which the measuring device 2 is not brought close, based on the statistical information S.

[0068] The tablet terminal 3 can switch between a magnetic display mode in which only the magnetic information m is displayed, a trajectory display mode in which only the trajectory information p is displayed, and a simultaneous display mode in which both the magnetic information m and the trajectory information p are displayed. This allows the user to simultaneously recognize the magnetic information m and the trajectory information p, and at the same time, to individually recognize the magnetic information m and the trajectory information p.

[0069] <Modifications> The present invention is not limited to the above embodiment and various modifications are possible. The measurement system 1 may include a device other than the tablet terminal 3 as a device for displaying the display screen IM. For example, the measurement system 1 may include a smartphone, a PC, or the like as a device for displaying the display screen IM. The measurement device 2 may be provided with a display unit. In this case, the measurement device 2 may display the display screen IM on the display unit provided in the measurement device 2 based on the detection results of the magnetic sensors 23A, 23B and the motion sensor 24.

[0070] The magnetic sensor provided in the measurement device 2 is not limited to an MR sensor, and may be another sensor (such as an MI sensor or a Hall element sensor) capable of measuring at least one of the strength and direction of a magnetic field. The number of magnetic sensors provided in the measurement device 2 is not limited to two, and may be one, or three or more. When the measurement device 2 is provided with multiple magnetic sensors, the magnetic data transmitted from the measurement device 2 to the tablet terminal 3 is not limited to the average value of the magnetic field strength measured by each of the multiple magnetic sensors. For example, the measurement device 2 may transmit the magnetic field strength measured by each of the multiple magnetic sensors directly to the tablet terminal 3 as magnetic data.

[0071] The magnetic sensors 23A and 23B may function as gradiometers. A gradiometer is a system that cancels out common-mode noise commonly input to multiple magnetic sensors by calculating the difference between the detection results of multiple magnetic sensors arranged at multiple spatially different positions (first-order differential type). For example, in the measurement device 2, by calculating the difference between the magnetic strengths measured by the magnetic sensors 23A and 23B, the shape of the magnetic field formed by an external magnetic body can be more accurately grasped.

[0072] Typically, the detection results of the magnetic sensors 23A and 23B have hysteresis characteristics, resulting in differences in the detection results between when the magnetic field strength increases and when it decreases. Hysteresis characteristics can degrade the accuracy of the first-order differential value, so when the magnetic sensors 23A and 23B function as gradiometers, the detection accuracy may decrease. Here, the absolute value of the ratio (hereinafter referred to as the "hysteresis amount") is defined as the ratio between the change in magnetic field strength as the denominator and the maximum difference between the detection results in the direction of magnetic field strength increase and decrease as the numerator. When measurements are performed using the measurement device 2, the hysteresis amount is preferably 1% or less, preferably 0.5% or less. In other words, by using magnetic sensors 23A and 23B with a hysteresis amount of 1% or less, preferably 0.5% or less, in the measurement device 2, these sensors can function effectively as gradiometers. Therefore, the measurement device 2 can accurately measure the first-order differential value of the magnetic field.

[0073] The motion sensor 24 provided in the measurement device 2 is not limited to a six-axis sensor. For example, the measurement device 2 may have a GPS sensor as a sensor for detecting the position.

[0074] The display form of the display screen IM is not limited to the above embodiment. For example, the tablet terminal 3 may set the shape of the unit of magnetic information U to be a triangle connecting the positions indicated by each of the three pieces of position data consecutively received from the measurement device 2. The tablet terminal 3 may calculate the average value of the magnetic field strength indicated by each of the three pieces of magnetic data associated with the three pieces of position data, and fill the triangular unit of magnetic information U with a color corresponding to the calculated average value. The color of the unit of magnetic information U corresponding to the magnetic field strength may be determined based on the maximum and minimum values ​​of the magnetic field strength indicated by each of all the magnetic data received during measurement.

[0075] For example, the tablet terminal 3 may display the magnetic information m using contour lines. Furthermore, for example, the tablet terminal 3 may display the trajectory information p using line segments connecting display positions indicated by the position data.

[0076] In the above embodiment, the strength of the magnetic field is displayed on the display screen IM. The display screen IM may display a plurality of small arrows indicating the direction of the magnetic field. Alternatively, the display screen IM may display both the strength and direction of the magnetic field. In this case, the strength of the magnetic field may be indicated by the color of the arrow, and the direction of the magnetic field may be indicated by the direction of the arrow.

[0077] In the above embodiment, a two-dimensional spatial distribution of the magnetic field strength is displayed on the display screen IM. However, the display screen IM may display a three-dimensional spatial distribution. In this case, as shown in FIG. 12 , for example, a display screen 91 displayed in the magnetic display mode and a display screen 92 displayed in the trajectory display mode may be switchable.

[0078] The size of the frame 90 of the display screen IM may be adjusted as appropriate depending on the size of the predetermined area R that the user desires to measure using the measurement device 2. For example, the user may first move the measurement device 2 in a rectangular shape so as to surround the predetermined area R. The tablet terminal 3 may identify the size and shape of the frame 90 of the display screen IM from the rectangular movement trajectory of the measurement device 2.

[0079] In the above embodiment, statistical information S was displayed in the statistical display portion if there was a portion (statistical display portion) adjacent to and sandwiched on both sides by unit magnetic information U in the display area 9 of the display screen IM where unit magnetic information U was not displayed. On the other hand, if there was a portion adjacent to unit magnetic information U in the display area 9 of the display screen IM where unit magnetic information U was not displayed, statistical information S may be displayed in this portion regardless of whether this portion is sandwiched on both sides by unit magnetic information U.

[0080] The color of the statistical information S is not limited to the case where it indicates the average value of the magnetic field strengths indicated by the adjacent magnetic information m. For example, the statistical information S may be displayed in a color corresponding to a value calculated by a statistical method, such as the median or mode of the magnetic field strengths indicated by the adjacent magnetic information m.

[0081] The simultaneous display mode, magnetic display mode, and trajectory display mode may be switched even during measurement by the measurement device 2.

[0082] The various parameters (time, period, etc.) in the above embodiment are merely examples, and it goes without saying that the present invention is not limited to these parameters.

[0083] <Others> The motion sensor 24 is an example of a "position detector" of the present invention. The tablet terminal 3 is an example of a "display device" of the present invention. The display 34 is an example of a "display unit" of the present invention. The CPU 21 that performs the processing of S33 is an example of an "output means" of the present invention. The CPU 31 that performs the processing of S53 is an example of an "acquisition means" of the present invention. The CPU 31 that performs the processing of S73 is an example of a "calculation means" of the present invention. The CPU 31 that performs the processing of S71 is an example of a "first display means" of the present invention. The CPU 31 that performs the processing of S75 is an example of a "second display means" of the present invention. The CPU 31 that performs the processing of S85 is an example of a "third display means" of the present invention. The CPU 31 that performs the processing of S91, S95, and S99 is an example of a "switching means" of the present invention. The processing of S33 is an example of an "output step" of the present invention. The processing of S53 is an example of an "acquisition step" of the present invention. The processing of S73 is an example of a "calculation step" of the present invention. The process of S71 is an example of the "first display step" of the present invention. The process of S75 is an example of the "second display step" of the present invention.

Claims

1. A measurement system comprising a measurement device having a magnetic sensor capable of detecting a magnetic field and a position detector capable of detecting a position, and a display device which acquires the detection results of the magnetic sensor and the position detector from the measurement device and displays them on a display unit, wherein the measurement device comprises an output means which associates magnetic data indicating the detection results of the magnetic sensor with position data indicating the detection results of the position detector and outputs them to the display device, and the display device comprises: an acquisition means which acquires the magnetic data and the position data from the measurement device; a calculation means which calculates a movement trajectory which indicates a change in the position of the measurement device over time based on the position data acquired by the acquisition means; a first display means which displays magnetic information which indicates at least one of the strength and direction of the magnetic field which is indicated by the magnetic data acquired by the acquisition means, in a display position within a predetermined display area of ​​the display unit which corresponds to the position of the measurement device which is indicated by the position data acquired by the acquisition means; and a second display means which displays trajectory information which indicates the movement trajectory calculated by the calculation means.

2. The measurement system described in claim 1, characterized in that the display area indicates a target area, which is an area of ​​space to be detected by the measurement device, the first display means displays the magnetic information as the measurement device moves within the target area, and the second display means displays the trajectory information as the measurement device moves within the target area.

3. The measurement system according to claim 1, characterized in that the second display means displays the trajectory information superimposed on the magnetic information displayed by the first display means.

4. The measurement system described in claim 1, further comprising a third display means for displaying statistical information calculated statistically based on the magnetic information in a portion of the display area where the magnetic information is not displayed.

5. The measurement system according to claim 4, wherein the statistical information indicates an average value of the magnetic information.

6. The measurement system according to claim 1, further comprising a switching means for switching between a state in which the magnetic information is displayed by the first display means and a state in which the trajectory information is displayed by the second display means.

7. The measurement system described in claim 1, characterized in that the measurement device has a plurality of the magnetic sensors, each of which is equipped with a gradiometer, and when the hysteresis amount is defined as the absolute value of the ratio between the amount of change in the strength of the magnetic field as the denominator and the maximum difference between the detection results in the direction in which the strength of the magnetic field increases and the direction in which it decreases as the numerator, the hysteresis amount of each of the plurality of the magnetic sensors is 0.5% or less.

8. A display method comprising: an acquisition step of acquiring magnetic data indicating the detection results of the magnetic sensor and position data indicating the detection results of the position detector from a measuring device having a magnetic sensor capable of detecting a magnetic field and a position detector capable of detecting a position; a calculation step of calculating a movement trajectory indicating a change in the position of the measuring device over time based on the position data acquired by the acquisition step; a first display step of displaying magnetic information indicating at least one of the strength and direction of the magnetic field indicated by the magnetic data acquired by the acquisition step in a display position corresponding to the position of the measuring device indicated by the position data acquired by the acquisition step within a specified display area of ​​a display unit; and a second display step of displaying trajectory information indicating the movement trajectory calculated by the calculation step.

9. A display program for causing a computer to execute the following steps: an acquisition step of acquiring magnetic data indicating the detection results of the magnetic sensor and position data indicating the detection results of the position detector from a measuring device having a magnetic sensor capable of detecting a magnetic field and a position detector capable of detecting a position; a calculation step of calculating a movement trajectory indicating a change in the position of the measuring device over time based on the position data acquired by the acquisition step; a first display step of displaying magnetic information indicating at least one of the strength and direction of the magnetic field indicated by the magnetic data acquired by the acquisition step in a display position corresponding to the position of the measuring device indicated by the position data acquired by the acquisition step within a specified display area of ​​a display unit; and a second display step of displaying trajectory information indicating the movement trajectory calculated by the calculation step.

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