JP2016170125A - Displacement measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a displacement measurement device capable of measuring the displacement magnitude of a measurement object while suppressing the power consumption.SOLUTION: A displacement measurement device (100) of the present invention includes: a rack gear unit (111) that moves in response to the displacement of the measurement object; a pinion gear unit (112) that rotates in conjunction with the movement of the rack gear unit; and an acceleration sensor (113) (gravitational acceleration sensor) that is disposed in the pinion gear unit and whose detection axis direction is set at the direction crossing the rotation axis of the pinion gear unit.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a displacement measuring device.

2. Description of the Related Art Conventionally, a device using a strain gauge is known as a displacement measuring device for measuring the displacement of a large structure such as a bridge.
FIG. 5 is a diagram illustrating an example of a displacement measuring apparatus 10 according to the prior art. One end side of the rack gear portion 11 constituting the displacement measuring device 10 is connected to a measurement object (not shown). When the measurement object is displaced in the longitudinal direction of the rack gear portion 11 (in the direction of the arrow in the figure), the rack gear portion 11 moves linearly, and the linear motion of the rack gear portion 11 at this time is converted into the rotational motion of the pinion gear portion 12. The The rotation angle of the pinion gear unit 12 is determined according to the amount of displacement of the measurement object.

  One end of a leaf spring 13 is attached to the pinion gear portion 12, and the other end of the leaf spring 13 is fixed to, for example, a structure (not shown) that supports the rotation shaft of the pinion gear portion 12. A strain gauge 14 is attached to the leaf spring 13, and a reading device 15 is connected to the strain gauge 14. When the pinion gear portion 12 rotates, the leaf spring 13 is deformed, and the leaf spring 13 is distorted. The distortion of the leaf spring 13 depends on the rotation amount of the pinion gear portion 12, and the rotation amount of the pinion gear portion 12 depends on the displacement amount of the measurement object. Therefore, the displacement amount of the measurement object can be known from the strain amount of the leaf spring 13.

  The strain gauge 14 detects the strain amount of the leaf spring 13 according to the displacement amount of the measurement object, and the reading device 15 reads the detection value of the strain gauge 14. As the strain gauge 14, an optical strain gauge that detects distortion using a change in the wavelength of a reflected wave in an optical fiber, or an electrical strain that detects distortion using a change in electrical resistance in a Wheatstone bridge. A meter is commonly used.

Japanese Patent No. 4721324

  According to the optical strain meter described above, when an optical fiber is damaged, a reflected wave from a part far from the damaged part cannot be obtained, so that distortion in a part far from the damaged part can be detected. Disappear. The longer the optical fiber length, the higher the frequency of this type of failure. For this reason, the wireless transmission system is preferable to the wired transmission system such as an optical fiber in that a failure due to damage to the transmission path that transmits the detected strain value is avoided.

  Here, in consideration of the fact that the wireless transmission method is intended for transmission of electrical signals, the electrical strain gauge that obtains the amount of distortion as an electrical signal is better than the optical strain meter that obtains the amount of distortion as an optical signal. Is also excellent in compatibility with the wireless transmission system. However, in order to take advantage of the wireless transmission method capable of avoiding a failure due to damage to the transmission path that transmits the distortion detection value, it is also necessary to avoid damage to the wiring that supplies power to the displacement measuring device. For this reason, when adopting a wireless transmission method, a form in which the power source of the displacement measuring device is remotely supplied by wire is not preferable, and it is necessary to provide a battery as the power source of the displacement measuring device.

  However, according to an electric strain meter that utilizes a change in electric resistance, it is necessary to constantly flow a current through the resistor, and the power consumption increases. For this reason, in applications where the displacement of large structures such as bridges is monitored over a long period of time (for example, 5 years or more), it is necessary to minimize the battery consumption of the displacement measuring device when the wireless transmission method described above is employed. It is difficult to use an electric strain gauge for the displacement measuring device.

  This invention is made | formed in view of the said subject, and it aims at providing the displacement measuring device which can measure the displacement amount of a measurement target object, suppressing power consumption.

A displacement measuring apparatus according to an aspect of the present invention includes a moving unit that moves in accordance with the displacement of a measurement object, a rotating unit that rotates in conjunction with the movement of the moving unit, and a detection axis direction. Has a configuration of a displacement measuring device including a gravitational acceleration sensor set in a direction intersecting with the rotation axis of the rotating unit.
In the displacement measuring apparatus, for example, the displacement measuring apparatus further includes an arithmetic processing unit for calculating a displacement amount of the measurement object based on a detection value of the gravitational acceleration sensor, and the arithmetic processing unit has the gravitational acceleration at a predetermined frequency. You may acquire the detection value of a sensor.
In the displacement measurement device, for example, the calculation processing unit calculates the displacement amount of the measurement object based on the detection value of the gravitational acceleration sensor acquired at the predetermined frequency, and then the displacement amount of the measurement object. The frequency of obtaining the detection value of the gravitational acceleration sensor may be changed based on the above.
In the displacement measuring apparatus, for example, a sub-rotation unit that rotates at a rotation radius larger than the rotation radius of the rotation unit in conjunction with the movement of the movement unit, and the sub-rotation unit are provided, and the detection axis direction is A sub-gravity acceleration sensor set in a direction intersecting with the rotation axis of the sub-rotation unit, wherein the arithmetic processing unit refers to a detection value of the sub-gravity acceleration sensor and rotates or rotates the rotation unit The direction may be specified.
In the displacement measuring apparatus, for example, the gravitational acceleration sensor may be a capacitance-type gravitational acceleration sensor.

  According to one aspect of the present invention, it is possible to measure the amount of displacement of a measurement object while suppressing power consumption.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows typically an example of the bridge to which the displacement measuring device by 1st Embodiment of this invention is applied, (A) is a general view of a bridge, (B) is a displacement measuring device attached. FIG. It is a figure which shows typically the structural example of the displacement measuring device by 1st Embodiment of this invention. It is a figure which shows typically the structural example of the displacement measuring device by 2nd Embodiment of this invention. It is a flowchart for demonstrating the operation example of the displacement measuring device by 2nd Embodiment of this invention. It is a figure which shows an example of the displacement measuring device by a prior art.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Here, the case where the displacement measuring device according to the embodiment of the present invention is applied to the displacement measurement of the bridge girder of the bridge is taken as an example, but the displacement measuring device according to the embodiment of the present invention can be applied to any application. It is.

(First embodiment)
FIG. 1 is a diagram schematically showing an example of a bridge to which a displacement measuring device 100 (FIG. 2 described later) according to the first embodiment of the present invention is applied, and (A) is an overall view of the bridge. (B) is an enlarged view of the vicinity of a part to which the displacement measuring device 100 is attached (part surrounded by a dotted circle).

The x-axis direction of the xyz coordinate system shown in FIGS. 1A and 1B indicates the longitudinal direction of the bridge, the y-axis direction indicates the width direction of the bridge, and the z-axis direction indicates the vertical direction. Yes. Therefore, FIG. 1 (A) is a side view of the bridge as viewed from the y-axis direction, and FIG. 1 (B) is a part of the bridge shown in FIG. 1 (A) (part surrounded by a dotted circle). It is the top view which looked at from the z-axis direction.
Note that each element illustrated in FIGS. 1A and 1B is expressed in an emphasized or simplified manner for convenience of description, and is not expressed on an actual scale.

  As shown in FIG. 1A, the bridge to which the displacement measuring device 100 according to the first embodiment is provided includes bridge girders 1A, 1B, and 1C as upper structures, and abutments 2A and 2B and piers as lower structures. 3A, 3B. The bridge girders 1A, 1B, and 1C are measurement objects of the displacement measuring apparatus 100 according to the first embodiment, and the displacement measuring apparatus 100 measures a relative displacement amount (for example, a gap or a step between piers) between the bridge girders.

  One end of the bridge girder 1A is supported by the abutment 2A, and the other end of the bridge girder 1A is supported by the pier 3A. One end side of the bridge girder 1B is supported by the pier 3A together with the other end of the bridge girder 1A, and the other end side of the bridge girder 1B is supported by the pier 3B. Furthermore, one end side of the bridge girder 1C is supported by the pier 3B together with the other end of the bridge girder 1B, and the other end side of the bridge girder 1C is supported by the abutment 2B.

  Further, as shown in FIG. 1B, a displacement measuring device 100 according to the first embodiment is attached in the vicinity of the connecting portion between the bridge beam 1A and the bridge beam 1B. Specifically, the main body 110 of the displacement measuring device 100 is fixed to the bridge girder 1A. Further, the measuring rod 111a protruding from the inside of the main body 110 of the displacement measuring device 100 is connected to a base 1BB fixed to the bridge beam 1B. The measuring rod 111a protruding from the displacement measuring device 100 moves in the longitudinal direction according to the relative displacement amount (gap or the like) between the bridge beam 1A and the bridge beam 1B.

FIG. 2 is a diagram schematically showing a configuration example of the displacement measuring apparatus 100 according to the first embodiment of the present invention.
The displacement measuring apparatus 100 includes a rack gear unit 111, a pinion gear unit 112, an acceleration sensor 113, an arithmetic processing unit 114, a displacement information storage unit 115, and a wireless communication unit 116 inside the main body 110. The rack gear portion 111 is a linear tooth-shaped gear having a plurality of teeth formed in a row along the longitudinal direction thereof, and is supported so as to be movable along the longitudinal direction. The rack gear unit 111 functions as a moving unit that moves in accordance with the relative displacement between the bridge girder 1A and the bridge girder 1B, which are measurement objects. A part of the rack gear part 111 protrudes from the main body part 110 as a measuring rod 111a. The end portion of the measuring rod 111a (the end portion of the rack gear portion 111) is connected to a pedestal 11B formed on the bridge beam 1B (FIG. 1).

  The pinion gear portion 112 is a spur gear having a rotation radius r, and is rotatably supported so that teeth formed on the outer periphery thereof mesh with teeth formed on the rack gear portion 111. The pinion gear unit 112 functions as a rotating unit that rotates in conjunction with the movement of the rack gear unit 111. The pinion gear unit 112 constitutes a so-called rack and pinion together with the rack gear unit 111 described above. The rotation shaft (not shown) of the pinion gear unit 112 is supported horizontally, and the rotation surface of the pinion gear unit 112 forms a vertical plane corresponding to the xz plane of the above-described xyz coordinate system. For this reason, the pinion gear part 112 rotates in a substantially vertical plane.

  An acceleration sensor 113 is attached near the center of rotation of the pinion gear portion 112. The acceleration sensor 113 is a capacitance-type gravitational acceleration sensor, and is a MEMS (Micro Electro Mechanical Systems) sensor. However, the present invention is not limited to this example, and the acceleration sensor 113 can be expressed as any other sensor such as a semiconductor sensor, an angle sensor, and an inclination angle sensor as long as gravitational acceleration can be detected. The direction of the detection axis JS of the acceleration sensor 113 is set so as to intersect with the rotation axis (not shown) of the pinion gear portion 112. Desirably, the direction of the detection axis JS of the acceleration sensor 113 is set to a direction substantially orthogonal to the rotation axis of the pinion gear portion 112.

  The direction of the detection axis JS of the acceleration sensor 113 is initially set so as to coincide with the vertical axis direction JV when the movement amount of the measuring rod 111a is zero, that is, when the rotation angle θ of the pinion gear portion 112 is zero. Yes. The acceleration sensor 113 generates and outputs a detection signal S (θ) indicating the rotation angle θ of the pinion gear unit 112 by detecting the gravitational acceleration component in the detection axis direction. The detection signal S (θ) output from the acceleration sensor 113 is supplied to the arithmetic processing unit 114.

The arithmetic processing unit 114 is an element for calculating the relative displacement amount D between the bridge beams of the measurement object based on the detection signal S (θ) of the acceleration sensor 113 indicating the rotation angle θ of the pinion gear unit 112. . This relative displacement amount D coincides with the movement amount M of the rack gear portion 111. As will be described later, the arithmetic processing unit 114 generates and outputs a displacement signal S (D) indicating a relative displacement amount D between the bridge beams of the measurement object from the movement amount M of the rack gear unit 111.
The displacement information storage unit 115 is an element for storing displacement information related to the relative displacement amount D calculated by the arithmetic processing unit 114, and may be configured from an arbitrary memory such as an SRAM (Static Random Access Memory).

  The wireless communication unit 116 is an element for performing transmission / reception of signals including various types of information via a wireless communication line with a wireless communication device provided in a remote management center (not shown) that manages the bridge. For example, each time the arithmetic processing unit 114 acquires the rotation angle θ of the pinion gear unit 112, or in response to a request from the wireless communication device of the management center, or periodically, the wireless communication unit 116 A displacement signal S (D) is transmitted to the wireless communication device of the management center through the communication line. The wireless communication unit 116 also receives an instruction signal including control information related to control of processing performed by the arithmetic processing unit 114 from the wireless communication device of the management center through the wireless communication line. However, the wireless communication unit 116 is an optional element provided as necessary, and may be provided outside the displacement measuring apparatus 100, or may be omitted. The wireless communication line includes any form of wireless communication.

Next, the operation of the displacement measuring apparatus 100 according to the first embodiment will be described.
Here, the operation of the displacement measuring device 100 will be described by paying attention to the processing of the arithmetic processing unit 114 when the bridge girder 1B is displaced with respect to the bridge girder 1A because the gap between the bridge girder 1A and the bridge girder 1B is enlarged. To do.
For convenience of explanation, the relative displacement amount D between the bridge beam 1A and the bridge beam 1B is the displacement amount of the bridge beam 1B with reference to the position of the bridge beam 1A to which the main body 110 of the displacement measuring device 100 is attached. The relative displacement D between the bridge beam 1A and the bridge beam 1B is referred to as the displacement amount D of the bridge beam 1B.

  As shown in FIG. 2, when the bridge girder 1B is displaced from the initial position Pa relative to the bridge girder 1A to the position Pb in the right hand direction of FIG. 2, the rack gear portion 111 moves in the right hand direction of FIG. The movement amount M of the rack gear portion 111 at this time indicates the displacement amount D of the bridge girder 1B. When the rack gear unit 111 moves in the right-hand direction in FIG. 2, the pinion gear unit 112 rotates in the right rotation direction (clockwise direction) in FIG.

  In this case, the rotation angle θ (radian) of the pinion gear portion 112 is determined by the rotation radius r of the pinion gear portion 112 and the movement amount M of the rack gear portion 111 (that is, the tooth movement distance along the outer periphery of the pinion gear portion 112). Is given by the following equation (1). As understood from the equation (1), the smaller the rotation radius r, the larger the rotation angle θ of the pinion gear portion 112 can be obtained. This means that the detection sensitivity of the displacement amount D (that is, the movement amount M) is improved.

  θ = M / r (1)

  The acceleration sensor 113 detects a gravitational acceleration component in the direction of the detection axis JS that changes according to the rotation angle θ of the pinion gear unit 112. The gravitational acceleration component in the direction of the detection axis JS is determined according to the rotation angle θ of the pinion gear unit 112. The acceleration sensor 113 outputs a detection signal S (θ) indicating the rotation angle θ of the pinion gear unit 112 corresponding to the gravitational acceleration component in the direction of the detection axis JS to the arithmetic processing unit 114.

  Here, since the movement amount M of the rack gear part 111 is equal to the displacement amount D of the bridge girder 1B, the above equation (1) can be rewritten as the following equation (2). The arithmetic processing unit 114 uses the following equation (2) to calculate the displacement D of the bridge girder 1B from the rotation angle θ of the pinion gear unit 112 indicated by the detection signal S (θ) and the rotation radius r of the pinion gear unit 112. Is calculated. The arithmetic processing unit 114 stores displacement information regarding the displacement amount D in the displacement information storage unit 115. In addition, the arithmetic processing unit 114 generates a displacement signal S (D) indicating the displacement amount D and outputs it to the wireless communication unit 116. The wireless communication unit 116 transmits the displacement signal S (D) to the wireless communication device in the management center through the wireless communication line.

  D = θ × r (2)

  In the above example, every time the displacement amount D is calculated by the arithmetic processing unit 114, the displacement signal S (D) indicating the displacement amount D itself is wirelessly transmitted to the remote management center. First, the arithmetic processing unit 114 reads the displacement amount D calculated previously (hereinafter referred to as “displacement amount D (n−1)”) from the displacement information storage unit 115, and the previous displacement amount D (n−1). And a difference signal indicating the difference between the displacement amounts D (ie, the amount of change in the displacement amount D), which is a difference between the displacement amount D calculated this time (hereinafter referred to as “displacement amount D (n)”). May be wirelessly transmitted as the displacement signal S (D).

  In the first embodiment, the arithmetic processing unit 114 acquires the rotation angle θ for calculating the displacement amount D by sampling the detection signal S (θ) of the acceleration sensor 113 at a predetermined frequency (or period). . For example, the arithmetic processing unit 114 acquires the rotation angle θ at a frequency that the rotation angle θ of the pinion gear unit 112 does not exceed 180 degrees. The reason for providing such a restriction on the acquisition frequency of the rotation angle θ is that if the rotation angle θ exceeds 180 degrees (2π radians) during the period from the sampling of the detection signal S (θ) to the next sampling, it moves. This is because the amount M (displacement amount D) cannot be calculated correctly.

  That is, if the rotation angle θ exceeds 180 degrees (2π radians) during the period from the sampling of the detection signal S (θ) to the next sampling, the rotation angle θ obtained by the next sampling is determined by the previous sampling. The rotation angle when the pinion gear 112 is rotated to the right or the rotation angle when the pinion gear 112 is rotated counterclockwise with reference to the obtained rotation angle θ, or the rotation when the pinion gear 112 is rotated It becomes impossible to specify whether it is a corner. In this case, the movement amount M (displacement amount D) cannot be calculated correctly.

  In the above-described example, the rotation angle θ of the pinion gear unit 112 is acquired at the above-described predetermined frequency. However, as long as the rotation direction of the pinion gear unit 112 can be specified according to the situation, The frequency may be changed. For example, a value that gives a relatively high frequency is set in the arithmetic processing unit 114 as an initial value of the frequency of acquiring the rotation angle θ of the pinion gear unit 112. The arithmetic processing unit 114 acquires the rotation angle θ of the pinion gear unit 112 at the frequency set as the initial value, and the frequency at which the rotation angle θ does not exceed 180 degrees from the tendency of the rotation angle θ to change over time. Is estimated. Thereafter, the arithmetic processing unit 114 changes the frequency of obtaining the rotation angle θ of the pinion gear unit 112 to the estimated frequency. If the frequency at which the rotation angle θ is acquired in this way is changed, the rotation angle θ is not acquired at an excessive frequency and is necessary for sampling the detection signal S (θ) output from the acceleration sensor 113. The power consumption of the arithmetic processing unit 114 can be suppressed.

  In addition, the frequency at which the arithmetic processing unit 114 acquires the rotation angle θ of the pinion gear unit 112 (hereinafter referred to as “acquisition frequency of the rotation angle θ”) is transmitted from a remote location through the above-described wireless communication line. It is good also as changeable by. For example, when it is predicted that a situation in which the displacement amount D changes suddenly due to an earthquake or the like after changing the acquisition frequency of the rotation angle θ to a small value according to the situation according to the above-described example will be monitored A maintenance manager residing in the center may reset the acquisition frequency of the rotation angle θ to a high value through the above-described wireless communication line. On the other hand, for example, when it is predicted that the displacement amount D cannot change suddenly, the maintenance manager stationed at the remote management center reduces the acquisition frequency of the rotation angle θ to a low value through the wireless communication line. You may reset it.

  According to the first embodiment described above, since the capacitance type MEMS sensor is used as the acceleration sensor 113, the detection signal S (θ) is detected as the voltage value of the capacitance of the acceleration sensor 113, and the acceleration is detected. A steady DC current does not flow through the sensor 113. Further, since the acceleration sensor 113 is a MEMS sensor, the capacitance value of the capacitance is reduced, and the current component required for charging / discharging can be reduced. Therefore, power consumption of the acceleration sensor 113 can be suppressed.

  Moreover, in the application which monitors the displacement of the bridge girder of a bridge, the displacement amount D shows a tendency to change little by little over a long period of time, and hardly changes rapidly in a short period of time. For this reason, the sampling frequency of the detection signal S (θ) by the arithmetic processing unit 114 can be set to a sufficiently small value. If the frequency of sampling the detection signal S (θ) is reduced, the power consumption of the arithmetic processing unit 114 can be suppressed.

  According to the first embodiment described above, since the capacitance type sensor is used as the acceleration sensor 113, the detection signal S (θ) is detected as the capacitance voltage of the acceleration sensor 113, and the acceleration sensor 113 is detected. However, no steady DC current flows. Further, since the acceleration sensor 113 is a MEMS sensor, the capacitance value is reduced, and the charge / discharge component of the capacitance of the acceleration sensor 113 can be reduced. Therefore, the power consumption of the acceleration sensor 113 can be effectively suppressed.

  In bridge applications, the displacement amount D tends to change little by little over a long period of time and rarely changes rapidly in a short period of time. For this reason, the frequency of sampling of the detection signal S (θ) by the arithmetic processing unit 114 can be sufficiently reduced. If the frequency of sampling the detection signal S (θ) is reduced, the power consumption of the arithmetic processing unit 114 can be suppressed.

  Therefore, according to the first embodiment, the power consumption of the displacement measuring apparatus 100 can be kept small. For this reason, when a battery is employed as the power source of the displacement measuring device 100 in an application in which the displacement signal S (D) related to the displacement amount D is transmitted using a wireless transmission method such as the wireless communication line described above, the battery is consumed. Therefore, the displacement measuring device 100 can be operated over a long period of time and the displacement amount D can be monitored stably. In this case, it is possible to prevent a failure such as disconnection peculiar to the wired transmission method, and to improve the reliability of the monitor.

(Second Embodiment)
Next, a second embodiment of the present invention will be described.
In the first embodiment described above, when the rotation angle θ of the pinion gear portion 112 is 180 degrees (2π radians) or more, it is necessary to avoid the disadvantage that the rotation direction cannot be specified. Although there is a restriction regarding the frequency of acquiring the rotation angle θ, the second embodiment makes it possible to monitor the displacement amount D without being restricted by the frequency of acquiring the rotation angle θ.

FIG. 3 is a diagram schematically illustrating a configuration example of a displacement measuring apparatus 200 according to the second embodiment of the present invention.
The displacement measuring apparatus 200 includes a main body 210 instead of the main body 110 in the configuration of the displacement measuring apparatus 100 according to the first embodiment shown in FIG. The main body 210 further includes a pinion gear 1120 and an acceleration sensor 1130 in addition to the rack gear 111, the pinion gear 112, and the acceleration sensor 113, which are components of the main body 110 of the displacement measuring apparatus 100 according to the first embodiment. Is provided. In addition, the main body unit 210 includes an arithmetic processing unit 1140 instead of the arithmetic processing unit 114 that is a constituent element of the main body unit 110 of the displacement measuring apparatus 100 according to the first embodiment.

  The “rotation angle θ1”, “detection signal S (θ1)”, “rotation radius r1”, and “detection axis JS1” shown in FIG. 3 are the pinion gear portions in the first embodiment shown in FIG. 112 corresponds to the rotation angle θ of 112, the detection signal S (θ) output from the acceleration sensor 113, the rotation radius r of the pinion gear portion 112, and the detection axis JS of the acceleration sensor 113.

  Here, the pinion gear portion 1120 is a spur gear having a rotation radius r2 larger than the rotation radius r1 of the pinion gear portion 112, and the teeth formed on the outer periphery thereof mesh with the teeth formed on the pinion gear portion 112. And is rotatably supported. The pinion gear unit 1120 functions as a sub-rotation unit that rotates in conjunction with the movement of the rack gear unit 111. The rotation axis (not shown) of the pinion gear unit 1120 is supported horizontally like the pinion gear unit 112, and the rotation surface of the pinion gear unit 112 forms a vertical plane corresponding to the xz plane of the above-described xyz coordinate system. That is, the pinion gear unit 1120 rotates in the same vertical plane as the pinion gear unit 112.

  Here, it is assumed that the rotation radius r2 of the pinion gear portion 1120 is four times the rotation radius r1 of the pinion gear portion 112. Therefore, when the pinion gear 112 rotates twice in the clockwise direction and the rotation angle θ1 becomes +720 degrees (+ 4π radians), the pinion gear 1120 rotates by a quarter in the counterclockwise rotation direction. θ2 is −90 degrees (−π / 2 radians). Conversely, when the pinion gear 112 rotates twice in the left rotation direction and the rotation angle θ1 becomes −720 degrees (−4π radians), the pinion gear 1120 rotates one quarter in the right rotation direction, The rotation angle θ2 is +90 degrees (+ π / 2 radians). Therefore, even if the rotation angle θ1 of the pinion gear portion 112 is ± 180 degrees or more, the rotation direction and the rotation speed of the pinion gear portion 112 can be specified from the rotation angle θ2 of the pinion gear portion 1120.

  However, the present invention is not limited to this example, and the rotation radius r1 of the pinion gear portion 112 and the pinion gear portion are limited to that the rotation direction and the rotation speed of the pinion gear portion 112 can be specified from the rotation angle θ2 of the pinion gear portion 1120. The ratio of the rotation radius 12 of 1120 can be set arbitrarily. In the second embodiment, the rotation radius r1 and the rotation radius r2 are less than +180 degrees (+ 2π radians) when the pinion gear portion 1120 reaches the maximum value Mmax (measurement limit value) when the movement amount M of the rack gear portion 111 reaches the maximum value Mmax. It is set to be.

  An acceleration sensor 1130 is attached near the rotation center of the pinion gear portion 1120. The acceleration sensor 1130 is a capacitance type acceleration sensor similar to the acceleration sensor 113 attached to the pinion gear unit 112, and is a MEMS sensor. A detection axis JS2 of the acceleration sensor 1130 is set in a direction intersecting with a rotation axis (not shown) of the pinion gear portion 1120. Desirably, the detection axis JS2 of the acceleration sensor 1130 is set in a direction orthogonal to the rotation axis of the pinion gear portion 1120.

  The direction of the detection axis JS2 of the acceleration sensor 1130 is such that the movement amount of the measuring rod 111a is zero, that is, the rotation angle θ1 of the pinion gear portion 112 and the rotation angle θ2 of the pinion gear portion 1120 are both zero. The initial setting is made to coincide with the vertical axis direction JV. The acceleration sensor 1130 outputs a detection signal S (θ2) indicating the rotation angle θ2 of the pinion gear portion 1120.

The detection signal S (θ1) output from the acceleration sensor 113 and the detection signal S (θ2) output from the acceleration sensor 1130 are supplied to the arithmetic processing unit 1140. The arithmetic processing unit 1140 determines the rotation speed or the rotation direction of the pinion gear unit 1120 with reference to the detection signal S (θ2) output from the acceleration sensor 1130, and the amount of movement of the rack gear unit 111 based on the determination result. M is calculated. This movement amount M coincides with the displacement amount D of the bridge girder 1B of the measurement object. The arithmetic processing unit 1140 generates and outputs a displacement signal S (D) indicating the displacement amount D of the bridge girder 1B of the measurement object.
Other configurations are the same as those of the first embodiment.

Next, the operation of the displacement measuring apparatus 200 according to the second embodiment will be described along the flowchart shown in FIG.
Here, as in the first embodiment, paying attention to the processing of the arithmetic processing unit 1140 when the bridge girder 1B is displaced with respect to the bridge girder 1A by expanding the gap between the bridge girder 1A and the bridge girder 1B, The operation of the displacement measuring apparatus 200 will be described.

The operation for the arithmetic processing unit 1140 to acquire the detection signal S (θ1) indicating the rotation angle θ1 of the pinion gear unit 112 is the same as in the first embodiment, and the description thereof is omitted.
When the bridge girder 1B is displaced in the right-hand direction in FIG. 3, the rack gear 111 moves in the right-hand direction in FIG. 3 by the movement amount M (= displacement amount D) according to the displacement amount D of the bridge girder 1B at that time. When the rack gear unit 111 moves, the pinion gear unit 112 rotates in the clockwise direction by the rotation angle θ1 (radian). When the pinion gear portion 112 rotates, the pinion gear portion 1120 rotates by the rotation angle θ2 in the left rotation direction. At this time, the absolute value of the rotation angle θ2 is a quarter of the absolute value of the rotation angle θ1.

  The acceleration sensor 1130 detects a gravitational acceleration component in the direction of the detection axis JS2 that changes according to the rotation angle θ2 of the pinion gear portion 1120. The gravitational acceleration component in the direction of the detection axis JS2 is determined according to the rotation angle θ2 of the pinion gear unit 1120. The acceleration sensor 1130 outputs a detection signal S (θ) indicating the rotation angle θ2 of the pinion gear unit 1120 corresponding to the gravitational acceleration component in the direction of the detection axis JS2.

  The arithmetic processing unit 1140 performs an acquisition process of the rotation angles θ1 and θ2 (step S1). That is, the arithmetic processing unit 1140 samples the detection signal S (θ1) of the acceleration sensor 113 and the detection signal S (θ2) of the acceleration sensor 1130 at a predetermined frequency, and thereby calculates the displacement D. The angles θ1 and θ2 are acquired. However, in the second embodiment, the predetermined frequency for sampling the detection signals S (θ1) and S (θ2) can be arbitrarily set without being restricted as described in the first embodiment.

  Subsequently, the arithmetic processing unit 1140 performs a case classification process for the rotation angle θ2 (step S2). Specifically, the arithmetic processing unit 1140 determines which of the following numerical ranges R1 to R4 the rotation angle θ2 (radian) of the pinion gear unit 1120 belongs to from the detection signal S (θ2) output from the acceleration sensor 1130. Determine.

(1) Numerical range R1; −π ≦ θ2 <−π / 2
(2) Numerical range R2; −π / 2 ≦ θ2 <0
(3) Numerical range R3; 0 ≦ θ2 <+ π / 2
(4) Numerical range R4; + π / 2 ≦ θ2 <π

  Here, when the pinion gear portion 112 rotates rightward (clockwise direction) and the rotation speed of the pinion gear portion 112 at that time is not less than one rotation and less than two rotations, the rotation angle θ2 of the pinion gear portion 1120 Belongs to the numerical range R1. Further, when the pinion gear portion 112 rotates rightward and the rotation speed of the pinion gear portion 112 at that time is less than one, the rotation angle θ2 of the pinion gear portion 1120 belongs to the numerical value range R2.

  Further, when the pinion gear portion 112 rotates in the left direction (counterclockwise direction) and the rotation speed of the pinion gear portion 112 at that time is less than once, the rotation angle θ2 of the pinion gear portion 1120 is in the numerical range R3. Belonging to. Further, when the pinion gear portion 112 rotates to the left and the rotation speed of the pinion gear portion 112 at that time is one rotation or more and less than two rotations, the rotation angle θ2 of the pinion gear portion 1120 belongs to the numerical value range R4. Therefore, by determining which of the numerical ranges R1 to R4 the rotation angle θ2 of the pinion gear portion 1120 belongs, the rotation direction and the rotation speed of the pinion gear portion 1120 can be specified.

  Subsequently, the arithmetic processing unit 1140 uses the relationship between the rotation number and rotation direction of the pinion gear unit 112 described above and the numerical range R1 to R4 to which the rotation angle θ2 belongs to calculate the rotation number of the pinion gear unit 112. A determination process is performed (step S3). For example, if the rotation angle θ2 belongs to the numerical value range R1, the arithmetic processing unit 1140 determines that the rotation speed of the pinion gear unit 112 is 1 rotation or more and less than 2 rotations.

  Subsequently, the arithmetic processing unit 1140 uses the relationship between the rotation speed and rotation direction of the pinion gear unit 112 and the numerical ranges R1 to R4 to which the rotation angle θ2 belongs, to determine the rotation direction of the pinion gear unit 112. A determination process is performed (step S4). For example, if the rotation angle θ2 belongs to the numerical value range R1, the arithmetic processing unit 1140 determines that the rotation direction of the pinion gear unit 112 is the right rotation direction (clockwise direction).

  Subsequently, the arithmetic processing unit 1140 is indicated by the rotation direction and the number of rotations of the pinion gear unit 112 obtained by the above determination processing (steps S2 and S3) and the detection signal S (θ1) output from the acceleration sensor 113. The displacement amount D is calculated using the rotation angle θ1. Specifically, the arithmetic processing unit 1140 determines that the rotation direction of the pinion gear unit 112 is the left rotation direction and the rotation number of the pinion gear unit 112 at that time is one rotation by the above determination processing (steps S2 and S3). When it is determined that the rotation is less than 2 rotations, the total clockwise rotation angle of the pinion gear portion 112 is expressed as “θ1-4π”, and the displacement amount D is calculated using the following equation (3a). .

  D = r1 × (θ1−4π) (3a)

  Further, the arithmetic processing unit 1140 determines that the rotation direction of the pinion gear unit 112 is the left rotation direction and the rotation speed of the pinion gear unit 112 at that time is less than one rotation by the above determination processing (steps S2 and S3). Is determined as “θ1-2π”, the displacement D is calculated using the following equation (3b).

  D = r1 × (θ1-2π) (3b)

  Further, the arithmetic processing unit 1140 determines that the rotation direction of the pinion gear unit 112 is the right rotation direction and the rotation speed of the pinion gear unit 112 at that time is less than one rotation by the above determination processing (steps S2 and S3). Is determined, the rotation amount θ1 of the pinion gear portion 112 in the clockwise direction is the rotation angle θ1 itself, so the displacement amount D is calculated using the following equation (3c).

  D = r1 × θ1 (3c)

  Further, the calculation processing unit 1140 determines that the rotation direction of the pinion gear unit 112 is the right rotation direction and the rotation number of the pinion gear unit 112 at that time is one rotation or more and 2 When it is determined that the rotation is less than the rotation, the total clockwise rotation angle of the pinion gear portion 112 is “θ1 + 2π”. Therefore, the following equation (3d) in which θ1 in (3c) is replaced with (θ1 + 2π) is used. The displacement amount D is calculated.

  D = r1 × (θ1 + 2π) (3d)

  As described above, the arithmetic processing unit 1140 determines the rotation direction and the rotation speed of the pinion gear unit 112 according to the numerical range R1 to R4 to which the rotation angle θ2 of the pinion gear unit 1120 belongs, and refers to the determination result. Thus, the total rotation angle from the initial value of the pinion gear unit 112 is calculated. Then, the arithmetic processing unit 1140 calculates the displacement amount D using the calculated total rotation angle.

Next, a modification of the second embodiment will be described.
In the example shown in FIG. 3, the pinion gear portion 1120 is connected to the rack gear portion 111 with the pinion gear portion 112 interposed therebetween, but the pinion gear portion 1120 may be directly connected to the rack gear portion 111. In this case, the method of connecting the pinion gear portion 1120 to the rack gear portion 111 is arbitrary, and for example, the pinion gear portion 1120 may be disposed at a position facing the pinion gear portion 112 with the rack gear portion 111 interposed therebetween. In this case, teeth may be formed on both the upper side and the lower side of the rack gear portion 111.

In this case, the pinion gear portion 1120 may be arranged so as to be aligned with the pinion gear portion 112 along the longitudinal direction of the rack gear portion 111. Thus, by directly connecting the pinion gear portion 1120 to the rack gear portion 111, the accuracy of the rotation angle θ2 of the pinion gear portion 1120 can be improved.
In the configuration of FIG. 3, the position of the pinion gear portion 112 and the position of the pinion gear portion 1120 may be interchanged, and the pinion gear portion 112 may be coupled to the rack gear portion 111 with the pinion gear portion 1120 interposed therebetween.

  According to the second embodiment described above, since the displacement amount D is calculated from the rotation angle θ1 of the pinion gear portion 112 having a small rotation radius r1, the displacement amount D can be monitored with high accuracy.

  Further, according to the second embodiment described above, the total rotation angle of the pinion gear unit 112 is calculated with reference to the rotation angle θ2 of the pinion gear unit 1120, and therefore the rotation angle of the pinion gear unit 112 is 180 degrees or more. Even if it exists, the displacement amount D can be calculated correctly. Therefore, it is possible to monitor a larger displacement amount D with higher accuracy than in the first embodiment.

  Further, according to the second embodiment described above, each detection signal of the acceleration sensors 113 and 1130 may be sampled only once within a range in which the rotation angle θ2 of the pinion gear portion 1120 does not exceed 180 degrees (π radians). There is no need to perform measurement at all times. For this reason, the power consumption in the arithmetic processing unit 1140 can be suppressed.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications, changes, additions, substitutions, and the like are possible without departing from the spirit of the present invention.
For example, in the above-described embodiment, the displacement amount of the measurement object is converted into the rotation angle of the detection axis of the acceleration sensor using the rack and pinion. For example, instead of the rack gear unit 111, a string-like moving unit is used. In place of the pinion gears 112 and 1120, a columnar rotating unit is used, and the string-shaped moving unit is wound around the columnar rotating unit, and the string-shaped moving unit is moved according to the amount of displacement of the measurement object. By unwinding the part from the rotating part, the linear motion due to the displacement of the measurement object may be converted into the rotational motion, similarly to the rack and pinion. In other words, any method can be used as a method for tilting the detection axis of the acceleration sensor in accordance with the displacement of the measurement object.

  DESCRIPTION OF SYMBOLS 100,200 ... Displacement measuring device, 110, 210 ... Main part, 111 ... Rack gear part (moving part), 111a ... Measuring rod, 112, 1120 ... Pinion gear part (rotating part), 113, 1130 ... Accelerometer, 114, DESCRIPTION OF SYMBOLS 1140 ... Operation processing part, 115 ... Displacement information storage part, 116 ... Wireless communication part.

Claims (5)

A moving part that moves according to the displacement of the measurement object;
A rotating unit that rotates in conjunction with the movement of the moving unit;
A gravitational acceleration sensor provided in the rotating unit and set in a direction in which a detection axis direction intersects the rotation axis of the rotating unit;
Displacement measuring device with An arithmetic processing unit for calculating a displacement amount of the measurement object based on a detection value of the gravitational acceleration sensor;
The displacement measurement apparatus according to claim 1, wherein the arithmetic processing unit acquires a detection value of the gravitational acceleration sensor at a predetermined frequency.   The arithmetic processing unit calculates a displacement amount of the measurement object based on a detection value of the gravity acceleration sensor acquired at the predetermined frequency, and then calculates the gravity acceleration sensor based on the displacement amount of the measurement object. The displacement measuring apparatus according to claim 2, wherein the frequency of acquiring the detected value is changed. In conjunction with the movement of the moving part, a sub-rotating part that rotates with a turning radius larger than the turning radius of the rotating part,
A sub-gravity acceleration sensor provided in the sub-rotation unit and set in a direction in which a detection axis direction intersects the rotation axis of the sub-rotation unit;
Further comprising
3. The displacement measuring device according to claim 1, wherein the arithmetic processing unit specifies a rotation speed or a rotation direction of the rotating unit with reference to a detection value of the sub-gravity acceleration sensor.   The displacement measuring apparatus according to claim 1, wherein the gravitational acceleration sensor is a capacitance-type gravitational acceleration sensor.

Images