Fixed state determination method, fixed state determination device, and fixed state determination system

Abstract

To provide a fixed state determination method, a fixed state determination device, and a fixed state determination system capable of determining a fixed state of an acceleration sensor unit with respect to an object to be measured.SOLUTION: This fixed state determination method is for determining a fixed state of an acceleration sensor unit fixed to an object to be measured. The acceleration sensor unit includes a pair of first acceleration sensors arranged side by side in a first direction with posture where detection axes are directed to opposite sides in the first direction to detect acceleration in the first direction. A first target value is determined from a first addition value obtained by adding together output signals of the first acceleration sensors at the same time, and the first target value is compared with a preset first determination reference value to determine the fixed state.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a fixation state determination method, a fixation state determination device, and a fixation state determination system. [Background technology]

[0002] The sensor unit described in Patent Document 1 includes a circuit board and an X-axis acceleration sensor, a Y-axis acceleration sensor, and a Z-axis acceleration sensor mounted on the circuit board. The X-axis acceleration sensor detects acceleration in the X-axis direction, the Y-axis acceleration sensor detects acceleration in the Y-axis direction, and the Z-axis acceleration sensor detects acceleration in the Z-axis direction. Such a sensor unit is fixed to an object to be measured when used. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-184453 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the sensor unit in Patent Document 1 is equipped with only one X-axis acceleration sensor, one Y-axis acceleration sensor, and one Z-axis acceleration sensor, which means that it is not possible to detect rotational motion acting on the sensor unit based on the output signal from the sensor unit, making it difficult to determine the fixed state of the sensor unit relative to the object being measured. [Means for solving the problem]

[0005] The method for determining a fixed state of an acceleration sensor unit fixed to a measurement object includes the steps of: the acceleration sensor unit includes a pair of first acceleration sensors arranged side by side in the first direction with their detection axes facing opposite directions along the first direction, and which together detect acceleration in the first direction; determining a first target value from a first sum obtained by adding up the output signals of the first acceleration sensors at the same time; The fixed state is determined by comparing the first target value with a preset first reference value.

[0006] The fixation state determination device of the present invention determines a fixation state of an acceleration sensor unit that is fixed to a measurement object, is arranged side by side in a first direction with each detection axis facing opposite to each other along the first direction, and includes a pair of first acceleration sensors that both detect acceleration in the first direction, an external interface for acquiring output signals from the pair of first acceleration sensors; and a processor that determines a first target value from a first sum value obtained by adding up the output signals of each of the first acceleration sensors at the same time, and determines the fixed state by comparing the first target value with a predetermined first reference value.

[0007] The fixation state determination system of the present invention includes an acceleration sensor unit that is fixed to a measurement object, is arranged side by side in a first direction with each detection axis facing opposite to each other along the first direction, and includes a pair of first acceleration sensors that together detect acceleration in the first direction; and a fixed state determination device that determines a first target value from a first sum value obtained by adding up the output signals of the first acceleration sensors at the same time, and determines the fixed state of the acceleration sensor unit relative to the measurement object by comparing the first target value with a predetermined first determination reference value. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a configuration diagram of a fixation state determination system according to a first embodiment. [Figure 2] FIG. 2 is an exploded perspective view of the acceleration sensor unit. [Figure 3] FIG. 2 is a cross-sectional view of the acceleration sensor unit as seen from the negative side in the Y-axis direction. [Figure 4] FIG. 1 is a cross-sectional view of the acceleration sensor unit as seen from the positive side in the Z-axis direction. [Figure 5] FIG. 10 is a plan view of the base as seen from the positive side in the Z axis direction. [Figure 6] FIG. 2 is a plan view of the acceleration sensor. [Figure 7] FIG. 2 is an exploded perspective view of an acceleration sensor element included in the acceleration sensor. [Figure 8] FIG. 2 is a diagram showing a state in which the acceleration sensor unit is attached to a measurement object. [Figure 9] 10 is a flowchart illustrating an example of a fixation state determination method. [Figure 10] FIG. 4 is a diagram illustrating an example of an output signal. [Figure 11] FIG. 10 is a diagram illustrating an example of a result of frequency spectrum analysis. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method, an apparatus, and a system for determining a fixed state according to the present invention will be described in detail below with reference to the embodiments shown in the accompanying drawings.

[0010] First Embodiment FIG. 1 is a configuration diagram of a fixation state determination system according to a first embodiment. FIG. 2 is an exploded perspective view of an acceleration sensor unit. FIG. 3 is a cross-sectional view of the acceleration sensor unit as seen from the negative side in the Y-axis direction. FIG. 4 is a cross-sectional view of the acceleration sensor unit as seen from the positive side in the Z-axis direction. FIG. 5 is a plan view of the base as seen from the positive side in the Z-axis direction. FIG. 6 is a plan view of the acceleration sensor. FIG. 7 is an exploded perspective view of an acceleration sensor element included in the acceleration sensor. FIG. 8 is a diagram showing a state in which the acceleration sensor unit is attached to a measurement object. FIG. 9 is a flowchart showing an example of a fixation state determination method. FIG. 10 is a diagram showing an example of an output signal. FIG. 11 is a diagram showing an example of the results of frequency spectrum analysis.

[0011] For ease of explanation, the three mutually perpendicular axes will be referred to as the X-axis, Y-axis, and Z-axis. For ease of explanation, the direction parallel to the X-axis will also be referred to as the "X-axis direction," the direction parallel to the Y-axis will also be referred to as the "Y-axis direction," and the direction parallel to the Z-axis will also be referred to as the "Z-axis direction." The arrowed side of each axis will also be referred to as the "plus side," and the opposite side will also be referred to as the "minus side." The positive side of the Z-axis direction will also be referred to as the "upper side," and the negative side of the Z-axis direction will also be referred to as the "lower side."

[0012] The fixed state determination system 100 shown in Figure 1 includes an acceleration sensor unit 1 fixed to a moving object such as an automobile, agricultural machinery, construction machinery, robot, or drone, or a structure such as a bridge, a building, or a foundation installed on the ground (hereinafter simply referred to as "measurement object Q"), and a fixed state determination device 9 that detects the attitude and behavior of the measurement object Q based on the output signals Sx1, Sx2, Sy1, Sy2, Sz1, and Sz2 of the acceleration sensor unit 1, and determines the fixed state of the acceleration sensor unit 1 relative to the measurement object Q.

[0013] 2, the acceleration sensor unit 1 has a built-in element 10 and a casing 8 that houses the built-in element 10. As shown in FIGS. 3 and 4, the built-in element 10 has a substrate 2, and X-axis acceleration sensors 3X1 and 3X2 as a pair of first acceleration sensors, Y-axis acceleration sensors 3Y1 and 3Y2 as a pair of second acceleration sensors, Z-axis acceleration sensors 3Z1 and 3Z2 as a pair of third acceleration sensors, a connector 6, and a processing circuit 7, all of which are mounted on the substrate 2.

[0014] In this embodiment, the differential pair of X-axis acceleration sensors 3X1 and 3X2 is a pair of first acceleration sensors, the differential pair of Y-axis acceleration sensors 3Y1 and 3Y2 is a pair of second acceleration sensors, and the differential pair of Z-axis acceleration sensors 3Z1 and 3Z2 is a pair of third acceleration sensors, but there is no particular limitation on which of the X-axis acceleration sensors 3X1 and 3X2, Y-axis acceleration sensors 3Y1 and 3Y2, and Z-axis acceleration sensors 3Z1 and 3Z2 is a pair of first acceleration sensors, a pair of second acceleration sensors, and a pair of third acceleration sensors.

[0015] Each part of the acceleration sensor unit 1 will be described below in order.

[0016] First, the casing 8 will be described. The casing 8 is made of aluminum (Al) and is formed by cutting, die-casting, or the like. In particular, in this embodiment, the surface is anodized to provide insulation. However, the constituent material and forming method of the casing 8 are not particularly limited. Also, as shown in FIG. 2, the casing 8 has a base 81 having a recess 811 opening on an upper surface 81a, and a lid 82 fixed to the upper surface 81a of the base 81 and closing the opening of the recess 811. A storage space S is formed inside the casing 8, and the built-in element 10 is stored in the storage space S.

[0017] As shown in FIG. 5, the base 81 has three protrusions 812 protruding from the upper surface 81a. The base 81 also has screw insertion holes 813 that penetrate the upper surface 81a and the lower surface 81b of each of the protrusions 812. The acceleration sensor unit 1 can be fixed to the measurement object Q using screws inserted into the screw insertion holes 813. As shown in FIG. 5, the lower surface 81b of the base 81 has an opening 814 that exposes the connector 6 to the outside of the casing 8. The base 81 also has a first seat 815 and a second seat 816 on which the substrate 2 is placed. Of these, the second seat 816 has a frame shape that surrounds the periphery of the opening 814.

[0018] On the other hand, the lid 82 is formed in a plate shape that avoids the three protrusions 812, and is screwed to the upper surface 81a of the base 81. A seal member 83 is interposed between the base 81 and the lid 82, ensuring airtightness of the storage space S.

[0019] Although the casing 8 has been described above, the configuration of the casing 8 is not particularly limited.

[0020] Next, we will explain the substrate 2. The substrate 2 is a circuit board, and is a multilayer rigid board formed with through-holes, electrodes, wiring, etc. (not shown). For example, a glass epoxy board, a composite board, a ceramic board, etc. can be used as the substrate 2.

[0021] 3, the substrate 2 has an upper surface 21 and a lower surface 22 which are opposite surfaces. The substrate 2 is placed on the first and second pedestals 815, 816 with the lower surface 22 facing the base 81. The substrate 2 is fixed to the first pedestal 815 by a fixing member R1 and is fixed to the second pedestal 816 by a fixing member R2. In particular, the fixing member R2 ensures that the accommodation space S is airtight.

[0022] 3 and 4, at the end of the board 2 on the positive side in the X-axis direction, Z-axis acceleration sensor 3Z1 is mounted on the upper surface 21, and Z-axis acceleration sensor 3Z2 is mounted on the lower surface 22. At the end of the board 2 on the negative side in the X-axis direction, X-axis acceleration sensors 3X1 and 3X2 are mounted on the upper surface 21, and a connector 6 is mounted on the lower surface 22. At the center of the board 2, Y-axis acceleration sensors 3Y1 and 3Y2 are mounted on the upper surface 21, and a processing circuit 7 is mounted on the lower surface 22. This arrangement allows these components to be arranged in a well-balanced manner on the board 2.

[0023] The above is a description of the substrate 2. However, the configuration of the substrate 2 is not particularly limited.

[0024] Next, the X-axis acceleration sensors 3X1 and 3X2, the Y-axis acceleration sensors 3Y1 and 3Y2, and the Z-axis acceleration sensors 3Z1 and 3Z2 will be described. Because these have similar configurations, they will be collectively referred to as "acceleration sensors 3" below. However, this is not limiting, and at least one of the X-axis acceleration sensors 3X1 and 3X2, the Y-axis acceleration sensors 3Y1 and 3Y2, and the Z-axis acceleration sensors 3Z1 and 3Z2 may have a different configuration from the others.

[0025] In describing the acceleration sensor 3, the three mutually perpendicular axes are referred to as the A-axis, B-axis, and C-axis. The direction along the A-axis is also referred to as the A-axis direction, the direction along the B-axis is also referred to as the B-axis direction, and the direction along the C-axis is also referred to as the C-axis direction. The arrowed side of each axis is also referred to as the "plus side," and the opposite side is also referred to as the "minus side." The plus side of the C-axis is also referred to as "up," and the minus side is also referred to as "down." The A-axis, B-axis, and C-axis are axes set for the acceleration sensor 3 and are different from the X-axis, Y-axis, and Z-axis, which are axes set for the acceleration sensor unit 1.

[0026] The acceleration sensor 3 can detect acceleration in the C-axis direction. As shown in Fig. 6, the acceleration sensor 3 has a package 31 and an acceleration sensor element 32 housed in the package 31.

[0027] The package 31 has a base 36 with a recess 361 that opens to the top surface, and a lid 37 that is bonded to the top surface of the base 36 so as to close the opening of the recess 361. A storage space S1 is formed inside the package 31, and the acceleration sensor element 32 is stored in the storage space S1. The package 31 has a rectangular parallelepiped shape when viewed from above in the C-axis direction. The package 31 is also shaped like a flat box, with its length in the C-axis direction (height) being shorter than its length in the A-axis direction (width) and its length in the B-axis direction (depth). For example, the base 36 is made of a ceramic such as alumina, and the lid 37 is made of a metal material such as Kovar.

[0028] As shown in FIG. 7, the acceleration sensor element 32 housed in such a package 31 has a substrate structure 33, an acceleration detection element 34 connected to the substrate structure 33, and a weight portion 35 arranged on the substrate structure 33.

[0029] Substrate structure 33 is formed from a quartz crystal substrate and has a flat plate shape along the AB plane perpendicular to the C-axis. Substrate structure 33 monolithically includes base 331, movable portion 332 that is displaceable in the C-axis direction relative to base 331, and four support portions 333a, 333b, 333c, and 333d that support base 331.

[0030] The base 331 is U-shaped and opens to the positive side in the B-axis direction. The movable part 332 is disposed inside the base 331 and is connected to the base 331 at its end on the negative side in the B-axis direction. A narrowed part 334 that is thinner than the surrounding area is formed at the boundary between the base 331 and the movable part 332. The narrowed part 334 functions as a hinge, making it easier for the movable part 332 to displace in the C-axis direction relative to the base 331. A weight 35 is provided on the upper surface of the movable part 332 via a bonding member P1. The weight 35 is made of a metal material such as copper (Cu), gold (Au), tungsten (W), or various alloys.

[0031] The support portions 333a, 333b, 333c, and 333d are arranged around the base portion 331 and are connected to the base portion 331. The support portions 333a, 333b, 333c, and 333d are arm-shaped and bent at right angles along the A-axis and the B-axis. The substrate structure 33 is fixed to a pedestal 362 of the base 36 at the free ends of the support portions 333a, 333b, 333c, and 333d.

[0032] The acceleration detection element 34 is a double-ended tuning fork vibration element formed from a quartz substrate. The acceleration detection element 34 has two vibrating beams 341 and 342, a first base 343 terminating one end of the two vibrating beams 341 and 342, and a second base 344 terminating the other end of the two vibrating beams 341 and 342. The acceleration detection element 34 has the vibrating beams 341 and 342 arranged along the B axis, and is fixed to the base 331 at the first base 343 and to the movable part 332 at the second base 344. The acceleration detection element 34 also has excitation electrodes (not shown) provided on the surfaces of the vibrating beams 341 and 342. When an AC voltage drive signal is applied to the excitation electrodes, the vibrating beams 341 and 342 flexurally vibrate so as to move away from or towards each other in the A axis direction.

[0033] The acceleration sensor 3 configured as described above detects acceleration in the C-axis direction as follows. When acceleration in the C-axis direction is applied to the acceleration detection element 34 while the acceleration detection element 34 is undergoing bending vibration, the movable part 332 is displaced in the C-axis direction relative to the base part 331, with the constricted part 334 acting as a fulcrum. This displacement then applies tensile or compressive stress to the acceleration detection element 34, and the resonant frequency of the acceleration detection element 34 changes depending on the magnitude of the applied stress. Therefore, the direction of acceleration can be detected by the increase or decrease in the frequency of the signal output from the acceleration sensor 3, and the magnitude of the acceleration can be detected from the amount of change in frequency.

[0034] Although the acceleration sensor 3 has been described above, the configuration of the acceleration sensor 3 is not limited to this as long as it can detect acceleration.

[0035] Next, the arrangement of the X-axis acceleration sensors 3X1 and 3X2, the Y-axis acceleration sensors 3Y1 and 3Y2, and the Z-axis acceleration sensors 3Z1 and 3Z2 will be described.

[0036] First, the arrangement of the X-axis acceleration sensors 3X1 and 3X2 will be described. The X-axis acceleration sensors 3X1 and 3X2 are acceleration sensors for detecting acceleration in the X-axis direction. As shown in FIG. 4, both X-axis acceleration sensors 3X1 and 3X2 are mounted vertically on the upper surface 21 of the substrate 2. The X-axis acceleration sensor 3X1 is oriented with its C-axis facing the negative side of the X-axis direction. In contrast, the X-axis acceleration sensor 3X2 is positioned next to the X-axis acceleration sensor 3X1 on the positive side of the X-axis direction, with its C-axis facing the positive side of the X-axis direction. In this way, the X-axis acceleration sensors 3X1 and 3X2 are oriented in an inverted manner relative to the other, in other words, with their detection axes facing opposite directions in the X-axis direction, and are arranged side by side facing each other in the X-axis direction. Therefore, the output signals of the X-axis acceleration sensors 3X1 and 3X2 are in opposite phases, i.e., have opposite signs (±).

[0037] Next, the arrangement of the Y-axis acceleration sensors 3Y1 and 3Y2 will be described. The Y-axis acceleration sensors 3Y1 and 3Y2 are acceleration sensors for detecting acceleration in the Y-axis direction. As shown in FIG. 4, the Y-axis acceleration sensors 3Y1 and 3Y2 are both mounted vertically on the upper surface 21 of the substrate 2. The Y-axis acceleration sensor 3Y1 is oriented with its C-axis facing the positive side of the Y-axis direction. In contrast, the Y-axis acceleration sensor 3Y2 is positioned next to the negative side of the Y-axis acceleration sensor 3Y1 and with its C-axis facing the negative side of the Y-axis direction. In this way, the Y-axis acceleration sensors 3Y1 and 3Y2 are arranged side by side in the Y-axis direction, with one sensor facing the other in an inverted orientation, in other words, with their detection axes facing opposite directions in the Y-axis direction. Therefore, the output signals of the Y-axis acceleration sensors 3Y1 and 3Y2 are out of phase with each other.

[0038] Next, the arrangement of the Z-axis acceleration sensors 3Z1 and 3Z2 will be described. The Z-axis acceleration sensors 3Z1 and 3Z2 are acceleration sensors for detecting acceleration in the Z-axis direction. As shown in FIG. 3, the Z-axis acceleration sensor 3Z1 is mounted horizontally on the upper surface 21 of the substrate 2, and the Z-axis acceleration sensor 3Z2 is mounted horizontally on the lower surface 22 of the substrate 2 so as to overlap the Z-axis acceleration sensor 3Z1 in a planar view from the Z-axis direction. The Z-axis acceleration sensor 3Z1 is oriented with its C-axis facing the positive side of the Z-axis direction. In contrast, the Z-axis acceleration sensor 3Z2 is oriented with its C-axis facing the negative side of the Z-axis direction. Thus, the Z-axis acceleration sensors 3Z1 and 3Z2 are arranged in an inverted orientation relative to the other, in other words, with their detection axes facing opposite directions in the Z-axis direction, and overlapping in the Z-axis direction. Therefore, the detection signals of the Z-axis acceleration sensors 3Z1 and 3Z2 are out of phase with each other.

[0039] Although the arrangement of the X-axis acceleration sensors 3X1 and 3X2, the Y-axis acceleration sensors 3Y1 and 3Y2, and the Z-axis acceleration sensors 3Z1 and 3Z2 has been described above, there is no particular limitation to the arrangement of these sensors.

[0040] Next, the connector 6 will be described. As shown in FIG. 3, the connector 6 is mounted on the lower surface 22 of the substrate 2. The connector 6 is exposed to the outside of the device through an opening 814. The connector 6 is a plug-type (male) connector, and has a plurality of pins aligned in two rows in the Y-axis direction. A socket-type (female) connector of the fixation state determination device 9 is connected to this connector 6, and electrical signals such as the driving voltage for the acceleration sensor unit 1 and detection data are transmitted and received between them.

[0041] Next, the processing circuit 7 will be described. As shown in FIG. 3, the processing circuit 7 is mounted on the underside 22 of the substrate 2. The processing circuit 7 is electrically connected to the X-axis acceleration sensors 3X1 and 3X2, the Y-axis acceleration sensors 3Y1 and 3Y2, the Z-axis acceleration sensors 3Z1 and 3Z2, and the connector 6 via the substrate 2, and controls the operation of each component required for the operation of the acceleration sensor unit 1. Specifically, the processing circuit 7 includes an oscillator circuit 71 that excites the acceleration detection elements 34 in the acceleration sensors 3X1, 3X2, 3Y1, 3Y2, 3Z1, and 3Z2, a counter 72 that counts the output frequency of the oscillator circuit 71, and an arithmetic circuit 73 that performs unit conversion and various correction processes on the count signal of the counter 72. The count signal processed by the arithmetic circuit 73 is output to the fixation state determination device 9 via the connector 6.

[0042] Such a processing circuit 7 is, for example, an MCU (Micro Controller Unit), and includes a storage medium such as a nonvolatile memory, an A / D converter, etc. The storage medium stores a program etc. required for detecting acceleration and outputting it to the fixation state determination device 9.

[0043] In the following, the count signal corresponding to the X-axis acceleration sensor 3X1 output from the acceleration sensor unit 1 will be referred to as output signal Sx1, the count signal corresponding to the X-axis acceleration sensor 3X2 will be referred to as output signal Sx2, the count signal corresponding to the Y-axis acceleration sensor 3Y1 will be referred to as output signal Sy1, the count signal corresponding to the Y-axis acceleration sensor 3Y2 will be referred to as output signal Sy2, the count signal corresponding to the Z-axis acceleration sensor 3Z1 will be referred to as output signal Sz1, and the count signal corresponding to the Z-axis acceleration sensor 3Z2 will be referred to as output signal Sz2.

[0044] The above describes the configuration of the acceleration sensor unit 1. However, the acceleration sensor unit 1 is not particularly limited as long as it has a pair of first acceleration sensors, and for example, one or two pairs of the X-axis acceleration sensors 3X1 and 3X2, the Y-axis acceleration sensors 3Y1 and 3Y2, and the Z-axis acceleration sensors 3Z1 and 3Z2 may be omitted.

[0045] Next, the fixation state determination device 9 will be described. As shown in FIG. 1 , the fixation state determination device 9 is electrically connected to the acceleration sensor unit 1 and controls the operation of the acceleration sensor unit 1. It detects accelerations occurring in the acceleration sensor unit 1 based on the output signals Sx1, Sx2, Sy1, Sy2, Sz1, and Sz2 output from the acceleration sensor unit 1, detects the posture and behavior of the measurement target Q based on the detected accelerations, and determines the fixation state of the acceleration sensor unit 1 to the measurement target Q based on the output signals Sx1, Sx2, Sy1, Sy2, Sz1, and Sz2. The fixation state determination device 9 may be composed of, for example, a general-purpose computer. The fixation state determination device 9 includes a processor (CPU) 91 for processing information, a memory 92 communicatively connected to the processor 91, an external interface 93 for connecting to an external device, and an output device 94 such as a display device for outputting information. The memory 92 stores various programs executable by the processor 91, and the processor 91 can read and execute the programs stored in the memory 92.

[0046] Below, we will explain a method for determining the fixed state of the acceleration sensor unit 1 to the measurement object Q based on the output signals Sx1, Sx2, Sy1, Sy2, Sz1, and Sz2. Prior to that, we will briefly explain one example of a method for fixing the acceleration sensor unit 1 to the measurement object Q. For example, as shown in FIG. 8, the acceleration sensor unit 1 is screwed to a base B, and the base B is further fixed to the measurement object Q. This configuration makes it easy to fix the acceleration sensor unit 1 to the measurement object Q in a predetermined orientation.

[0047] In such a fixing method, if there is any rattle in the acceleration sensor unit 1 relative to the base B, or rattle in the base B relative to the measurement object Q, or rattle between the components that make up the base B, the accuracy of detecting the posture and behavior of the measurement object Q will decrease. Therefore, the fixation state determination device 9 determines whether the fixation state of the acceleration sensor unit 1 to the measurement object Q is normal or abnormal based on the rotational component applied to the acceleration sensor unit 1 due to the rattle. Note that, for ease of explanation, hereinafter, rattle in the acceleration sensor unit 1 relative to the base B, rattle in the base B relative to the measurement object Q, etc. will be collectively referred to simply as "rattle in the acceleration sensor unit 1."

[0048] First, we will briefly explain the principle of the fastening state determination of the acceleration sensor unit 1 performed by the fastening state determination device 9. The output signals Sx1 and Sx2 of the X-axis acceleration sensors 3X1 and 3X2 are expressed by the following equations (1) and (2), respectively. Note that in the equations, Lx1 and Lx2 are the linear acceleration (F=ma) of the X-axis acceleration sensors 3X1 and 3X2, and Cx1 and Cx2 are the centrifugal force (F=mω) generated by the rotational movement of the X-axis acceleration sensors 3X1 and 3X2 around the Z axis. 2 r), σx1, and σx2 are noise components contained in the output signals Sx1 and Sx2.

[0049] Sx1=Lx1+Cx1+σx1…(1) Sx2=Lx2+Cx2+σx2…(2)

[0050] As described above, the output signals Sx1 and Sx2 are in opposite phase to each other, so the following equations (3) and (4) are derived.

[0051] Lx1=-Lx2…(3) Sx1+Sx2=(Cx1+Cx2)+(σx1+σx2)…(4)

[0052] By calculating or measuring (σx1+σx2) in advance and making it known, the rotational component (Cx1+Cx2) can be found from equation (4). Then, based on the magnitude of the found (Cx1+Cx2), the fixation state determination device 9 determines whether the fixation state of the acceleration sensor unit 1 to the measurement object Q is normal or abnormal. Note that (Cx1+Cx2) in equation (4) is largest when the central axis of the rotational motion is located between the pair of X-axis acceleration sensors 3X1 and 3X2, and decreases as the central axis moves away from that point.

[0053] The above is a brief explanation of the principle of how the fixation state determination device 9 determines the fixation state of the acceleration sensor unit 1. Next, the actual processing performed by the fixation state determination device 9 will be described.

[0054] Before the fixation state determination device 9 determines the fixation state, (σx1 + σx2) in equation (4) is calculated or measured in advance as preparation for the fixation state determination. Furthermore, a first determination reference value TH1 to be used for the fixation state determination is stored in the memory 92 based on the determined (σx1 + σx2). In this embodiment, the acceleration sensor unit 1 is first driven at the zero point (stationary state), and a first sum Sx obtained by adding the output signals Sx1 and Sx2 output at the same time is sampled multiple times to determine the effective value (root mean square value: RSM value) of the amplitude of the first sum Sx. Furthermore, the first determination reference value TH1 is determined by adding an allowable value that takes into account tolerances, the accuracy required for the acceleration sensor unit 1, and the like to the determined effective value. However, the method for determining the first determination reference value TH1 is not particularly limited. For example, instead of the effective value, the peak-to-peak value of the amplitude of the reference value may be calculated, and the first judgment reference value TH1 may be determined by adding an allowable value that takes into account tolerances, the accuracy required for the acceleration sensor unit 1, and the like to the calculated peak-to-peak value. Also, since the X-axis acceleration sensors 3X1 and 3X2 have the same configuration, assuming σx1 = σx2, the relationship (σx1 + σx2) = σx1 × √2 holds. Therefore, the first judgment reference value TH1 may be determined by adding an allowable value that takes into account tolerances, the accuracy required for the acceleration sensor unit 1, and the like to the calculated σx1 × √2.

[0055] As shown in FIG. 9, when the fixation state determination process begins, the processor 91 of the fixation state determination device 9 first acquires the output signal Sx1 from the X-axis acceleration sensor 3X1 and the output signal Sx2 from the X-axis acceleration sensor 3X2 at the same time via the external interface 93 in step S101. In step S102, the processor 91 calculates a first sum Sx (=Sx1+Sx2) by adding the output signals Sx1 and Sx2. FIG. 10 shows an example of the output signals Sx1 and Sx2. Note that the vertical axis in FIG. 10 indicates the count value, which corresponds to the resonant frequency of the acceleration detection element 34, i.e., the acceleration. As mentioned above, it can be seen from FIG. 10 that the output signals Sx1 and Sx2 are generally in opposite phase to each other. In step S103, the processor 91 acquires the first sum Sx a predetermined number of times at a predetermined cycle using a similar method, thereby generating first time-series data Tsx indicating the time variation of the first sum Sx. In step S104, the processor 91 determines the amplitude of the first time-series data Tsx as a target value to be compared in step S105. In this embodiment, the effective value or peak value of the amplitude is used as the amplitude of the first time-series data Tsx. This facilitates the comparison of the amplitude of the first time-series data Tsx with the first judgment reference value TH1. Whether the effective value or peak value is used as the amplitude of the first time-series data Tsx can be determined, for example, in accordance with the method for determining the first judgment reference value TH1. For example, if the first judgment reference value TH1 is determined using the effective value, the effective value can be used for the amplitude of the first time-series data Tsx. If the first judgment reference value TH1 is determined using the peak value, the peak value can be used for the amplitude of the first time-series data Tsx.

[0056] In step S105, the processor 91 compares the amplitude of the first time-series data Tsx, which is the first target value, with a first judgment reference value TH1. This comparison allows the magnitude of the rotational component (Cx1 + Cx2) of the acceleration sensor unit 1 to be determined. In other words, it allows the degree of rattle occurring in the acceleration sensor unit 1 due to an abnormal fixation to be determined. If the amplitude of the first time-series data Tsx is equal to or greater than the first judgment reference value TH1, the processor 91 determines in step S106 that the fixation state of the acceleration sensor unit 1 relative to the measurement object Q is abnormal, since the rattle occurring in the acceleration sensor unit 1 exceeds the allowable value. Conversely, if the amplitude of the first time-series data Tsx is less than the first judgment reference value TH1, the processor 91 determines in step S107 that the fixation state of the acceleration sensor unit 1 relative to the measurement object Q is normal, since the rattle occurring in the acceleration sensor unit 1 is within the allowable value. In step S108, the processor 91 outputs the fixation state determined in step S106 or S107 via the output device 94. In this way, according to the determination method based on the magnitude of the rotational component, it is possible to easily detect whether the fixation state of the acceleration sensor unit 1 relative to the measurement object Q is normal or abnormal.

[0057] The above describes a fixation state determination method. This fixation state determination method determines the fixation state of the acceleration sensor unit 1 fixed to the measurement object Q. The acceleration sensor unit 1 includes a pair of X-axis acceleration sensors 3X1 and 3X2, which are arranged side by side in the X-axis direction with their detection axes facing opposite each other along the X-axis direction, which is a first direction, and which detect acceleration in the X-axis direction. The output signals Sx1 and Sx2 of the X-axis acceleration sensors 3X1 and 3X2 at the same time are added together to determine a first object value Sx. The fixation state of the acceleration sensor unit 1 is determined by comparing the first object value with a predetermined first determination reference value TH1. This determination method makes it easy to determine whether the fixation state of the acceleration sensor unit 1 to the measurement object Q is normal or abnormal by utilizing the rotational component generated in the acceleration sensor unit 1.

[0058] As described above, the first sum Sx is continuously acquired to generate first time-series data Tsx indicating the change over time of the first sum Sx, and the amplitude of the first time-series data Tsx is determined as the first target value. According to this method, it is possible to easily determine whether the state of fixation of the acceleration sensor unit 1 to the measurement target Q is normal or abnormal.

[0059] As described above, the effective value of the amplitude of the first time-series data Tsx is used as the first target value, which makes it easier to compare the first target value with the first judgment reference value TH1.

[0060] As described above, the peak value of the amplitude of the first time-series data Tsx is used as the first object value, which makes it easy to compare the amplitude of the first object value with the first judgment reference value TH1.

[0061] As described above, the fixation state determination device 9 is a device for determining the fixation state of the acceleration sensor unit 1, which is fixed to the measurement object Q and includes a pair of first acceleration sensors, X-axis acceleration sensors 3X1 and 3X2, which are fixed to the measurement object Q and arranged side by side in the X-axis direction with their detection axes facing opposite each other along the X-axis direction, which is a first direction, and which both detect acceleration in the X-axis direction. The device includes an external interface 93 that acquires output signals Sx1 and Sx2 from the pair of X-axis acceleration sensors 3X1 and 3X2, and a processor 91 that determines a first object value Sx by adding the output signals Sx1 and Sx2 of each X-axis acceleration sensor 3X1 and 3X2 at the same time, and compares the first object value with a predetermined first determination reference value TH1 to determine the fixation state of the acceleration sensor unit 1 to the measurement object Q. With this configuration, it is possible to easily determine whether the fixation state of the acceleration sensor unit 1 to the measurement object Q is normal or abnormal by utilizing the rotational component generated in the acceleration sensor unit 1.

[0062] As described above, the fixation state determination system includes an acceleration sensor unit 1 that is fixed to measurement object Q and includes X-axis acceleration sensors 3X1 and 3X2 that are a pair of first acceleration sensors that are arranged side by side in the X-axis direction with their detection axes facing opposite each other along the X-axis direction, which is a first direction, and that both detect acceleration in the X-axis direction, and a fixation state determination device 9 that determines a first object value Sx by adding together the output signals Sx1 and Sx2 of X-axis acceleration sensors 3X1 and 3X2 at the same time, and compares the first object value with a predetermined first determination reference value TH1 to determine the fixation state of acceleration sensor unit 1 to measurement object Q. With this configuration, it is possible to easily determine whether the fixation state of acceleration sensor unit 1 to measurement object Q is normal or abnormal by utilizing the rotational component generated in acceleration sensor unit 1.

[0063] Second Embodiment This embodiment is similar to the first embodiment described above, except for the method of determining the fixed state of the acceleration sensor unit 1. In the following explanation, the present embodiment will be described mainly with respect to differences from the first embodiment described above, and explanations of similar points will be omitted.

[0064] In the first embodiment described above, it was explained that the output signals Sx1 and Sx2 of the X-axis acceleration sensors 3X1 and 3X2 satisfy the relationships in equations (1) to (4), but the output signals Sy1 and Sy2 of the Y-axis acceleration sensors 3Y1 and 3Y2 also satisfy the relationships in equations (5) to (8) below. Note that in the equations, Ly1 and Ly2 are the linear accelerations of the Y-axis acceleration sensors 3Y1 and 3Y2, Cy1 and Cy2 are the centrifugal forces generated by the rotational movement of the Y-axis acceleration sensors 3Y1 and 3Y2 about the Z axis, and σy1 and σy2 are the noise components contained in the output signals Sy1 and Sy2.

[0065] Sy1=Ly1+Cy1+σy1…(5) Sy2=Ly2+Cy2+σy2…(6) Ly1 = -Ly2…(7) Sy1+Sy2=(Cy1+Cy2)+(σy1+σy2)…(8)

[0066] Similarly, the output signals Sz1 and Sz2 of the Z-axis acceleration sensors 3Z1 and 3Z2 are expressed by the following equations (9) to (12). Note that in the equations, Lz1 and Lz2 are the linear accelerations of the Z-axis acceleration sensors 3Z1 and 3Z2, Cz1 ​​and Cz2 are the centrifugal forces generated by the rotational motion of the Z-axis acceleration sensors 3Z1 and 3Z2 around the X and Y axes, and σz1 and σz2 are the noise components contained in the output signals Sz1 and Sz2.

[0067] Sz1=Lz1+Cz1+σz1…(9) Sz2=Lz2+Cz2+σz2…(10) Lz1 = -Lz2…(11) Sz1+Sz2=(Cz1+Cz2)+(σz1+σz2)…(12)

[0068] Next, the actual processing performed by the fixed state determination device 9 will be described. Before the fixed state determination device 9 performs a fixed state determination, a first determination reference value TH1 is determined and stored in the memory 92 as preparation for the fixed state determination. The method of determining the first determination reference value TH1 is the same as in the first embodiment described above. Also, in the same manner as for the first determination reference value TH1, (σy1+σy2) in equation (8) is found by calculation or measurement, and a second determination reference value TH2 used for the fixed state determination is stored in the memory 92 based on the found (σy1+σy2). Furthermore, (σz1+σz2) in equation (12) is found by calculation or measurement, and a third determination reference value TH3 used for the fixed state determination is stored in the memory 92 based on the found (σz1+σz2).

[0069] 9, when fixation state determination is started, the processor 91 of the fixation state determination device 9 first acquires the output signal Sx1 of the X-axis acceleration sensor 3X1, the output signal Sx2 of the X-axis acceleration sensor 3X2, the output signal Sy1 of the Y-axis acceleration sensor 3Y1, the output signal Sy2 of the Y-axis acceleration sensor 3Y2, the output signal Sz1 of the Z-axis acceleration sensor 3Z1, and the output signal Sz2 of the Z-axis acceleration sensor 3Z2 at the same time in step S101. In step S102, the processor 91 calculates a first sum Sx by adding the output signals Sx1 and Sx2, a second sum Sy by adding the output signals Sy1 and Sy2, and a third sum Sz by adding the output signals Sz1 and Sz2. In a similar manner, the processor 91 acquires the first, second, and third sum values ​​Sx, Sy, and Sz a predetermined number of times at a predetermined period, thereby generating, in step S103, first time series data Tsx indicating the time change of the first sum value Sx, second time series data Tsy indicating the time change of the second sum value Sy, and third time series data Tsz indicating the time change of the third sum value Sz.

[0070] In step S104, the processor 91 calculates the amplitude of the first time series data Tsx, which is the first target value, the amplitude of the second time series data Tsy, which is the second target value, and the amplitude of the third time series data Tsz, which is the third target value. In this embodiment, the effective value of the amplitude or the peak value is used as the amplitude of the first time series data Tsx. The same applies to the amplitude of the second time series data Tsy and the amplitude of the third time series data Tsz.

[0071] In step S105, the processor 91 compares the first target value with the first judgment reference value TH1, the second target value with the second judgment reference value TH2, and the third target value with the third judgment reference value TH3. Then, the processor 91 comprehensively considers the results of these three comparisons to determine whether the fixed state of the acceleration sensor unit 1 with respect to the measurement object Q is normal or abnormal. For example, if at least one of the following is satisfied: first target value ≥ first judgment reference value TH1, second target value ≥ second judgment reference value TH2, or third target value ≥ third judgment reference value TH3, the processor 91 determines in step S106 that the fixed state of the acceleration sensor unit 1 with respect to the measurement object Q is abnormal because the rattle occurring in the acceleration sensor unit 1 exceeds the allowable value. If the first target value ≧ first judgment reference value TH1, the second target value ≧ second judgment reference value TH2, and the third target value ≧ third judgment reference value TH3 are not all satisfied, the processor 91 may determine in step S107 that the fixed state of the acceleration sensor unit 1 relative to the measurement object Q is normal because the rattle occurring in the acceleration sensor unit 1 is within the allowable value.

[0072] Alternatively, for example, the fixation state determination device 9 may determine that the fixation state of the acceleration sensor unit 1 to the measurement object Q is abnormal if all of the following conditions are satisfied: first target value ≥ first judgment reference value TH1, second target value ≥ second judgment reference value TH2, and third target value ≥ third judgment reference value TH3; and may determine that the fixation state of the acceleration sensor unit 1 to the measurement object Q is normal if at least one of them is not satisfied. In this way, by comprehensively taking into account the three comparison results and determining whether the fixation state of the acceleration sensor unit 1 to the measurement object Q is normal or abnormal, the determination can be made more accurately. Furthermore, the fixation state determination device 9 can also determine in which direction the acceleration sensor unit 1 is wobbling based on the three comparison results.

[0073] As described above, in the fixation state determination method of this embodiment, the acceleration sensor unit 1 includes a pair of Y-axis acceleration sensors 3Y1 and 3Y2 arranged side by side in the Y-axis direction with their detection axes facing opposite each other along the Y-axis direction, which is a second direction orthogonal to the X-axis direction, and which detect acceleration in the Y-axis direction. A second object value is determined from a second sum Sy obtained by adding together the output signals Sy1 and Sy2 of the Y-axis acceleration sensors 3Y1 and 3Y2 at the same time, and the fixation state of the acceleration sensor unit 1 is determined by comparing the second object value with a predetermined second judgment reference value TH2. This method allows the fixation state of the acceleration sensor unit 1 to the measurement object Q to be accurately determined using the comparison results between the first object value and the first judgment reference value TH1 and the comparison results between the second object value and the second judgment reference value TH2.

[0074] As described above, the acceleration sensor unit 1 includes a pair of third acceleration sensors, Z-axis acceleration sensors 3Z1 and 3Z2, arranged side by side in the Z-axis direction with their detection axes facing opposite directions along the Z-axis, which is a third direction orthogonal to the X-axis and Y-axis directions, and which detect acceleration in the Z-axis direction. The third target value Sz is determined from a third sum Sz obtained by adding the output signals Sz1 and Sz2 of the Z-axis acceleration sensors 3Z1 and 3Z2 at the same time, and the third target value is compared with a predetermined third judgment reference value TH3 to determine the fixation state of the acceleration sensor unit 1. This method accurately determines the fixation state of the acceleration sensor unit 1 relative to the measurement object Q using the comparison results of the first target value with the first judgment reference value TH1, the comparison results of the second target value with the second judgment reference value TH2, and the comparison results of the third target value with the third judgment reference value TH3.

[0075] The second embodiment can also achieve the same effects as the first embodiment described above.

[0076] Third Embodiment FIG. 11 is a diagram showing an example of the result of the frequency spectrum analysis.

[0077] This embodiment is similar to the first embodiment described above, except for the method of determining the fixed state of the acceleration sensor unit 1. In the following description, differences between this embodiment and the first embodiment will be mainly described, and descriptions of similar points will be omitted. In addition, in the drawings of this embodiment, the same reference numerals are used to designate the same components as those in the previous embodiment.

[0078] In this embodiment, the fixation state determination device 9 performs frequency spectrum analysis on the first time series data Tsx and compares the acceleration spectral density (ASD) obtained by the frequency spectrum analysis with a first determination reference value TH1 that is set in advance based on noise components contained in the first time series data Tsx, thereby determining the fixation state of the acceleration sensor unit 1 with respect to the measurement object Q. An example of frequency spectrum analysis is shown in FIG. 11. This method also makes it possible to easily determine the fixation state of the acceleration sensor unit 1 with respect to the measurement object Q.

[0079] Furthermore, in this embodiment, the fixation state determination device 9 sets a first judgment reference value TH1 for each of a plurality of frequency bands in the acceleration spectral density, and compares the acceleration spectral density, which is a first target value, with the first judgment reference value TH1 for each frequency band. In this embodiment, as shown in FIG. 11 , the acceleration spectral density is divided into a first region W1 of 1 Hz or more but less than 100 Hz and a second region W2 of 100 Hz or more but less than 200 Hz. The fixation state determination device 9 stores a first judgment reference value TH11 for the first region W1 and a first judgment reference value TH12 for the second region W2. However, the number of divided frequency bands is not limited to two and may be three or more. Furthermore, the range of each frequency band is not particularly limited.

[0080] The method for determining the first judgment reference values ​​TH11 and TH12 is not particularly limited. In this embodiment, the acceleration sensor unit 1 is first driven at the zero point (stationary state), and multiple samples are taken of a first sum Sx, which is the sum of the output signals Sx1 and Sx2 output at the same time, to generate first time-series data Tsx indicating the temporal change of the first sum Sx. Next, the first time-series data Tsx is subjected to frequency spectrum analysis, and the first judgment reference values ​​TH11 and TH12 are determined by adding a tolerance that takes into account the tolerance, the accuracy required for the acceleration sensor unit 1, and other factors to the result. More specifically, the first judgment reference value TH11 is determined by adding a tolerance that takes into account the tolerance, the accuracy required for the acceleration sensor unit 1, and other factors to the maximum value of the acceleration spectral density in the first region W1. The first judgment reference value TH12 is determined by adding a tolerance that takes into account the tolerance, the accuracy required for the acceleration sensor unit 1, and other factors to the maximum value of the acceleration spectral density in the second region W2.

[0081] The fixation state determination device 9 then compares the maximum value of the acceleration spectral density of the first region W1, which is the first target value of the first region W1, with a first judgment reference value TH11, and compares the maximum value of the acceleration spectral density of the second region W2, which is the first target value of the second region W2, with a first judgment reference value TH12. The fixation state determination device 9 then comprehensively considers the results of these two comparisons to determine whether the fixation state of the acceleration sensor unit 1 with respect to the measurement object Q is normal or abnormal. For example, if at least one of the following conditions is satisfied: the first target value of the first region W1≧the first judgment reference value TH11, or the first target value of the second region W2≧the first judgment reference value TH12, the fixation state determination device 9 determines that the fixation state of the acceleration sensor unit 1 with respect to the measurement object Q is abnormal because the rattle occurring in the acceleration sensor unit 1 exceeds the allowable value. If neither of these conditions is satisfied, the fixation state determination device 9 determines that the rattle occurring in the acceleration sensor unit 1 with respect to the measurement object Q is normal because the rattle occurring in the acceleration sensor unit 1 is within the allowable value.

[0082] Furthermore, the fixed state determination device 9 can determine where a rattle occurs in the acceleration sensor unit 1 based on the two comparison results. For example, if the first object value in the first region W1 is equal to or greater than the first judgment reference value TH11, it can be determined that the base B is rattling relative to the measurement object Q. If the first object value in the second region W2 is equal to or greater than the first judgment reference value TH12, it can be determined that the acceleration sensor unit 1 is rattling relative to the base B. Also, if the first object value in the first region W1 is equal to or greater than the first judgment reference value TH11 and the first object value in the second region W2 is equal to or greater than the first judgment reference value TH12, it can be determined that both of the above two rattles are occurring. This allows the fixed state of the acceleration sensor unit 1 to be determined in more detail.

[0083] As described above, in the fixation state determination method of this embodiment, frequency spectrum analysis is performed on the first time series data Tsx, and the first object value is determined from the acceleration spectral density obtained by the frequency spectrum analysis. This method also makes it possible to easily determine the fixation state of the acceleration sensor unit 1 relative to the measurement object Q.

[0084] As described above, the first judgment reference value TH1 is set for each of multiple frequency bands in the acceleration spectral density, and the acceleration spectral density is compared with the first judgment reference value TH1 for each frequency band. In this embodiment, the acceleration spectral density is divided into a first region W1 and a second region W2, and first judgment reference values ​​TH11 and TH12 are set for the first and second regions W1 and W2. The first target value, which is the acceleration spectral density of the first region W1, is compared with the first judgment reference value TH11, and the first target value, which is the acceleration spectral density of the second region W2, is compared with the first judgment reference value TH12. This method allows for more precise determination of the fixation state by frequency, enabling more accurate determination. For example, it is possible to determine the cause of the rattle in the acceleration sensor unit 1, as well as the details and extent of the rattle.

[0085] The third embodiment can also achieve the same effects as the first embodiment described above.

[0086] In this embodiment, the first judgment reference value TH11 is determined by adding an allowable value that takes into account the maximum value of the acceleration spectrum density in the first region W1, tolerances, the accuracy required for the acceleration sensor unit 1, and the like. However, the present invention is not limited to this. For example, the first judgment reference value TH11 may be determined by adding an allowable value that takes into account the average value of the acceleration spectrum density in the first region W1, tolerances, the accuracy required for the acceleration sensor unit 1, and the like. In this case, the average value of the acceleration spectrum density in the first region W1 obtained during abnormality judgment is compared with the first judgment reference value TH11. The same applies to the first judgment reference value TH12.

[0087] Furthermore, similarly to the first time series data Tsx, a frequency spectrum analysis may be performed on the second time series data Tsy, and a second target value, which is an acceleration spectral density (ASD) obtained by the frequency spectrum analysis, may be compared with a second judgment reference value TH2 preset based on noise components contained in the second time series data Tsy. Furthermore, a frequency spectrum analysis may be performed on the third time series data Tsz, and a third target value, which is an acceleration spectral density (ASD) obtained by the frequency spectrum analysis, may be compared with a third judgment reference value TH3 preset based on noise components contained in the third time series data Tsz. According to this method, the fixation state of the acceleration sensor unit 1 with respect to the measurement object Q can be accurately determined using two or three comparison results.

[0088] The fixation state determination method, fixation state determination device, and fixation state determination system of the present invention have been described above based on the illustrated embodiments, but the present invention is not limited to these, and the configuration of each part can be replaced with any configuration or process having a similar function. Furthermore, any other configuration or process may be added to the present invention. Furthermore, the respective embodiments may be combined as appropriate. [Explanation of symbols]

[0089] 1...acceleration sensor unit, 10...built-in element, 100...fixation state determination system, 2...substrate, 21...upper surface, 22...lower surface, 3...acceleration sensor, 3X1...X-axis acceleration sensor, 3X2...X-axis acceleration sensor, 3Y1...Y-axis acceleration sensor, 3Y2...Y-axis acceleration sensor, 3Z1...Z-axis acceleration sensor, 3Z2...Z-axis acceleration sensor, 31...package, 32...acceleration sensor element, 33...substrate structure, 331...base, 332...movable part, 333a...support part, 333b...support part, 333c...support part, 333d...support part, 334...constricted part, 34...acceleration detection element, 341...vibrating beam, 342...vibrating beam, 343...first base part, 344...second base part, 35...weight part, 36...base, 361...recess, 362...pedestal, 37...lid , 6...connector, 7...processing circuit, 71...oscillating circuit, 72...counter, 73...arithmetic circuit, 8...casing, 81...base, 81a...upper surface, 81b...lower surface, 811...recess, 812...projection, 813...screw insertion hole, 814...opening, 815...first base, 816...second base, 82...lid, 83...sealing member, 9...fixed state determination device, 91...processor, 92...memory, 93...external interface, 94...output device, B...base, P1...jointing member, Q...measurement object, R1...fixing member, R2...fixing member, S...accommodating space, S1...accommodating space, Sx...first added value, Sx1...output signal, Sx2...output signal, Sy1...output signal, Sy2...output signal, Sz1...output signal, Sz2...output signal, W1...first region, W2...second region

Claims

1. A method for determining a fixed state of an acceleration sensor unit fixed to a measurement object, comprising: the acceleration sensor unit includes a pair of first acceleration sensors arranged side by side in the first direction with their detection axes facing opposite directions along the first direction, and which together detect acceleration in the first direction; determining a first target value from a first sum obtained by adding up the output signals of the first acceleration sensors at the same time; The method for determining the fixed state comprises determining the fixed state by comparing the first target value with a first determination reference value that is set in advance.

2. continuously acquiring the first sum to generate first time series data indicating a change over time in the first sum; The fixation state determination method according to claim 1 , wherein the amplitude of the first time series data is determined as the first target value.

3. The fixation state determination method according to claim 2 , wherein an effective value of the amplitude is used as the first target value.

4. The fixation state determination method according to claim 2 , wherein a peak value of the amplitude is used as the first target value.

5. continuously acquiring the first sum to generate first time series data indicating a change over time in the first sum; The fixation state determination method according to claim 1 , wherein the first target value is determined from an acceleration spectral density obtained by frequency spectrum analysis of the first time series data.

6. setting the first judgment reference value for each of a plurality of frequency bands in the acceleration spectral density; The fixation state determination method according to claim 5, wherein the acceleration spectral density is compared with the first determination reference value for each of the frequency bands.

7. The fixation state determination method according to claim 2 , wherein the first determination reference value is set based on a noise component contained in the first time-series data.

8. The fixation state determination method according to claim 1 , wherein the fixation state is determined to be abnormal when the first target value is equal to or greater than the first determination reference value.

9. the acceleration sensor unit includes a pair of second acceleration sensors arranged side by side in a second direction perpendicular to the first direction with their detection axes facing opposite directions along the second direction, and both detecting acceleration in the second direction; determining a second target value from a second sum obtained by adding up the output signals of the second acceleration sensors at the same time; 7. The method for determining a fixed state according to claim 1, wherein the fixed state is determined by comparing the second target value with a second predetermined reference value.

10. the acceleration sensor unit includes a pair of third acceleration sensors arranged side by side in a third direction perpendicular to the first direction and the second direction, with their detection axes facing opposite directions along the third direction, and both detecting acceleration in the third direction; determining a third target value from a third sum obtained by adding up the output signals of the third acceleration sensors at the same time; The method for determining the fixed state according to claim 9 , wherein the fixed state is determined by comparing the third target value with a third reference value that is set in advance.

11. A fixation state determination device that determines a fixation state of an acceleration sensor unit including a pair of first acceleration sensors that are fixed to a measurement object, arranged side by side in a first direction with their detection axes facing opposite each other along the first direction, and that both detect acceleration in the first direction, an external interface for acquiring output signals from the pair of first acceleration sensors; a processor that determines a first target value from a first sum obtained by adding up the output signals of each of the first acceleration sensors at the same time, and determines the fixed state by comparing the first target value with a predetermined first determination reference value.

12. an acceleration sensor unit including a pair of first acceleration sensors fixed to the measurement object, arranged side by side in the first direction with their detection axes facing opposite directions along the first direction, and configured to detect acceleration in the first direction together; a fixed state determination device that determines a first target value from a first sum value obtained by adding up the output signals of each of the first acceleration sensors at the same time, and determines the fixed state of the acceleration sensor unit relative to the measurement object by comparing the first target value with a predetermined first determination reference value.

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