JP2014032054A - Acceleration sensor - Google Patents

Abstract

An acceleration sensor that can accurately measure translational acceleration and rotational acceleration with a single sensor and is easy to install.
A sensor for measuring the acceleration of a measuring object M, provided at both ends of the measuring object M and provided between the supporting member 3 made of an elastic material and between the both ends of the supporting member 3. The inertia member 4 and the sensor part 10 attached to the support member 3 are provided. The sensor part 10 has two FBG parts 12 in which a fiber Bragg grating is formed on an optical fiber 11, and includes two The FBG portion 12 is attached at a position sandwiching the inertia member 4 in the support member 3 so that both axial directions are parallel to each other.
[Selection] Figure 1

Description

  The present invention relates to an acceleration sensor. More specifically, the present invention relates to an acceleration sensor using an optical fiber in which a fiber Bragg grating (FBG) is formed.

  A fiber Bragg grating (FBG) is one in which a periodic refractive index change is formed in the core of an optical fiber. In the case of an optical fiber provided with an FBG, when light is incident, light having a specific wavelength is transmitted or reflected based on the characteristics of the FBG. For this reason, when distortion occurs in the FBG portion, the grating interval of the grating varies based on deformation (elongation or contraction) of the FBG, and the frequency or wavelength of light transmitted or reflected changes.

  The vibration and acceleration are measured using such properties of the FBG (for example, Patent Documents 1 and 2).

  In the techniques of Patent Documents 1 and 2, a weight or the like is directly connected to the optical fiber on which the FBG is formed, and the vibration is measured by directly measuring the expansion and contraction of the optical fiber. Patent Document 2 describes that translational acceleration and rotational angular acceleration can be measured.

However, in the technique of Patent Document 1, since the weight is only attached in the middle of the optical fiber with both ends fixed, it is impossible to grasp in which direction the weight is moving. Therefore, even if it can be detected that vibration or the like has occurred, the direction of acceleration cannot be specified.
In Patent Document 2, since six or more optical fibers are used, there is a possibility that the translational acceleration and the rotational angular acceleration can be measured, but the structure becomes very complicated.
Moreover, in the techniques of Patent Documents 1 and 2, since the weight load is directly applied to the optical fiber, the optical fiber may be damaged if the acceleration applied to the weight increases.

  On the other hand, instead of connecting the optical fiber directly to the weight, a technology has been developed to measure the acceleration by attaching the FBG of the optical fiber to a member (support member) connected to the weight and detecting the deformation of the support member by the FBG. (Patent Document 3).

  In Patent Document 3, the measurement object itself or a fixed part formed of a rigid body attached to the measurement object, and a fixed end supported from the lower surface of the fixed part and suspended in the vertical direction, the other end is a free end. Wavelength detector for measuring the reflected wavelength with a built-in light source, and a detection body made of an elastic body, a weight fixed to the free end of the detection body, a fiber Bragg grating (sensor FBG) provided on the detection body And an optical accelerometer comprising:

  In the optical accelerometer of Patent Document 3, when acceleration occurs in the measurement object, the fixed part moves integrally with the measurement object, but the weight moves inertially. Therefore, an acceleration difference occurs between the two, and this acceleration Due to the difference, the detection body is bent and the sensor FBG attached to the detection body is also bent (deformed). Since the deformation ratio of the sensor FBG changes in accordance with the acceleration of the measurement object, the acceleration of the measurement object can be detected by detecting the deformation ratio of the sensor FBG, that is, the expansion / contraction strain of the sensor FBG. .

JP 2004-12280 A JP 2001-281347 A JP 2005-30796 A

  However, since the optical accelerometer of Patent Document 3 can only measure acceleration in one direction, that is, acceleration in a direction parallel to the bending direction of the sensing object, the case where the acceleration direction of the measurement object changes, that is, To measure rotational acceleration, multiple optical accelerometers must be used. Moreover, in order to accurately measure rotational acceleration, the relative positions of a plurality of optical accelerometers must be accurately positioned and installed, which requires labor and cost to install the optical accelerometer. There's a problem.

  In view of the above circumstances, an object of the present invention is to provide an acceleration sensor that can accurately measure translational acceleration and rotational acceleration with a single sensor and that is easy to install.

An acceleration sensor according to a first aspect of the invention is a sensor for measuring acceleration of a measurement object, and is provided in the middle between both ends of the support member formed of an elastic material, both ends of which are fixed to the measurement object. An inertia member, and a sensor portion attached to the support member. The sensor portion has two FBG portions each having a fiber Bragg grating formed on an optical fiber. The two FBG portions are The support member is attached to a position sandwiching the inertia member so that the axial directions of the both are parallel to each other.
The acceleration sensor according to a second aspect is characterized in that, in the first aspect, the two FBG portions are provided so as to be symmetric with respect to the inertia member.
The acceleration sensor according to a third aspect of the present invention is the acceleration sensor according to the first or second aspect, wherein the support member is formed by a plate-like member, and the two FBG portions include an axial direction of each FBG portion and an axial direction of the support member. Each FBG part is being fixed to the surface of the said supporting member so that may become mutually parallel.
An acceleration sensor according to a fourth aspect of the present invention is a sensor for measuring the acceleration of a measurement object, and includes a fixing member fixed to the measurement object and an elastic member having a base end fixed to the fixing member so that the tip is a free end. A pair of support members formed of a material; a pair of inertia members provided at the tips of the pair of support members; and a sensor unit attached to the pair of support members. The members are provided so as to be symmetric with respect to the fixing member, and the sensor unit includes two FBG units in which fiber Bragg gratings are formed on an optical fiber, and the two FBG units are The pair of support members are attached so that both axial directions are parallel to each other.
According to a fifth invention, in the fourth invention, the two FBG portions are provided so as to be symmetrical to each other with the fixing member interposed therebetween.
According to a sixth aspect of the present invention, in the fourth or fifth aspect of the invention, the pair of support members are formed by plate-like members, and the pair of support members have the same central axis of the pair of support members. The two FBG portions are arranged so as to swing along the reference plane, and the two FBG portions are arranged such that the axial directions of the respective FBG portions are parallel to the reference surface. The FBG portions are fixed to the pair of support members, respectively.
According to a seventh aspect of the present invention, in the acceleration sensor according to any one of the first to sixth aspects, the sensor unit includes two fiber Bragg gratings formed on one optical fiber to form the two FBG units. It is characterized by.

According to the first invention, if both ends of the support member are attached to the measurement object, a difference in the movement acceleration occurs between the measurement object and the inertia member when the movement acceleration of the measurement object changes. Then, due to the difference in movement acceleration, the support member undergoes deformation corresponding to the difference in movement acceleration, that is, deformation corresponding to the acceleration of the measurement target. Since the FBG portion of the sensor portion is attached to the support member, distortion occurs in the FBG portion in response to the deformation of the support member. For this reason, since the deformation | transformation which has generate | occur | produced in the support member can be grasped | ascertained if the distortion of an FBG part is measured, the acceleration of a measuring object can be measured based on the deformation | transformation of this support member. In addition, since the two FBGs are provided so as to sandwich the inertia member, not only the translational acceleration of the measurement object but also the rotational acceleration can be measured based on the deformation state of the two FBGs.
According to the second invention, the translational acceleration and rotational acceleration of the measurement object can be accurately measured.
According to the third aspect of the present invention, the movement of the support member is limited in the direction intersecting the surface of the support member. Therefore, if the normal direction of the surface of the support member matches the direction in which the acceleration is to be measured, Acceleration can be accurately measured.
According to the fourth aspect of the invention, if the fixed member is attached to the measurement target, the movement amount between the fixed member and the inertia member (in other words, between the measurement target and the inertia member) when the movement acceleration of the measurement target changes. There will be a difference. Then, due to the difference in the movement acceleration, the support member undergoes deformation corresponding to the difference in movement acceleration, that is, deformation corresponding to the acceleration of the measurement target. Since the FBG portions of the sensor portions are respectively attached to the pair of support members, the FBG portions are also distorted corresponding to the deformation of the pair of support members. Therefore, if the strain of each FBG portion is measured, the deformation occurring in the pair of support members can be grasped, and the acceleration of the measurement object can be measured based on the deformation of the pair of support members. Moreover, a pair of support members are provided so as to sandwich the fixing member. That is, since the two FBGs are provided so as to sandwich the fixing member, not only the translational acceleration of the measurement object but also the rotational acceleration can be measured based on the deformation state of the two FBGs.
According to the fifth aspect, the translational acceleration and rotational acceleration of the measurement object can be accurately measured.
According to the sixth aspect of the present invention, the deformation of the pair of support members is limited to the direction along the reference plane. Therefore, if the reference plane is set to the direction in which the acceleration is to be measured, the acceleration in a predetermined direction is accurately measured. can do.
According to the seventh invention, since there is only one optical fiber, strain measurement of a plurality of FBG units can be performed with one apparatus. Therefore, when the sensor is used, the measuring device and the like can be reduced in size and simplified.

It is a schematic explanatory drawing of the acceleration sensor 1 of this embodiment, (A) is a schematic explanatory drawing at the time of fixing the supporting member 3 to the measuring object M directly, (B) shows the supporting member 2 via the case 2. It is a schematic explanatory drawing at the time of fixing to the measuring object M. It is explanatory drawing when acceleration is added to the measuring object M to which the acceleration sensor 1 of this embodiment is attached, (A) is explanatory drawing when translational acceleration is added, and (B) is rotational acceleration added. It is explanatory drawing in the case. It is a schematic explanatory drawing of the acceleration sensor 1 of other embodiment.

Next, an embodiment of the present invention will be described with reference to the drawings.
The acceleration sensor 1 of the present embodiment is a sensor for measuring the acceleration applied to the measuring object M to which the sensor is attached, using an optical fiber on which a fiber Bragg grating (FBG) is formed. One acceleration sensor 1 is characterized in that not only translational acceleration but also rotational acceleration can be measured.

  The acceleration sensor 1 of the present invention is a device in which it is difficult to use an electrical sensor due to the influence of electromagnetic waves or the like, and is attached to a measurement object M that may generate not only translational acceleration but also rotational acceleration. Can be used. For example, it can be used by being attached to an automobile, an airplane, a railroad, etc., but the measurement object M is not particularly limited.

(Description of the acceleration sensor 1 of the present embodiment)
As shown in FIG. 1, the acceleration sensor 1 of the present embodiment includes a support member 3 attached to the measurement target M, an inertia member 4 provided on the support member 3, and a sensor unit 10 attached to the support member 3. It has.

(About support member 3)
First, the support member 3 is a long member extending along the axial direction, and both ends in the axial direction are attached to the measuring object M. For example, if the measurement object M has a pair of wall surfaces W1, W2 that are spaced apart from each other as shown in FIG. 1A, both ends of the support member 3 may be fixed to the pair of wall surfaces W1, W2, respectively. .

The support member 3 is a member formed of a material having elasticity, and can be deformed by bending between both ends.
For example, a metal bar or a wire can be used as the support member 3, but a plate-like member is preferable. In the case of a plate-like member, it can be considered that the deformation is only bending deformation substantially along the normal direction of the surface. Then, as will be described later, when the acceleration of the measuring object M is measured by the sensor unit 10, the direction of the measured acceleration can be accurately specified. In other words, since only the acceleration in the direction in which the support member 3 bends can be measured, the measurement accuracy of the acceleration in the predetermined direction applied to the measurement object M can be increased. For example, in FIG. 1A, if the support member 3 is a plate material having a width in a direction perpendicular to the paper surface, the support member 3 has a normal direction of the plate-like surface, in other words, the vertical direction in FIG. That is, it can bend only in the thickness direction of the plate. Therefore, since only the acceleration in the vertical direction in FIG. 1, which is the direction in which the support member 3 bends, can be measured, the direction of the measured acceleration can be accurately specified.

(Inertial member 4)
As shown in FIG. 1A, an inertia member 4 such as a weight is provided at an intermediate portion between both ends of the support member 3. In other words, the inertia member 4 is attached to the measurement object M via the support member 3. The inertia member 4 is formed to have a mass that can bend the support member 3 between both ends when acceleration is applied to the measurement target M.
When the acceleration is applied to the measurement target M, if the support member 3 is bent only by the mass of the support member 3 itself, the inertia member 4 may not be provided, but the inertia member 4 is provided. This is preferable because the measurement sensitivity to acceleration can be improved.

(About sensor unit 10)
As shown in FIG. 1, the acceleration sensor 1 of the present embodiment includes a sensor unit 10. The sensor unit 10 includes two optical fibers 11 each having a portion where a fiber Bragg grating (FBG) is formed (hereinafter referred to as an FBG portion 12).

  First, FBG is one in which a periodic refractive index change is formed in the core of an optical fiber. In the case of an optical fiber provided with an FBG, when light is incident, light having a specific wavelength is transmitted or reflected based on the characteristics of the FBG. On the other hand, when the FBG is deformed (elongated or contracted), the lattice spacing of the grating varies with the deformation, and the wavelength of the transmitted or reflected light changes. For this reason, an FBG is formed on an optical fiber, a part where the FBG is formed is attached to an object, light is incident on the optical fiber, and a change in frequency (frequency shift) or a change in wavelength of light transmitted or reflected through the FBG ( Wavelength shift). Then, based on this frequency shift and wavelength shift, it is possible to grasp the deformation of the part where the FBG is attached to the object.

  In the sensor unit 10 of the acceleration sensor 1 of the present embodiment, an FBG is formed in the core of the optical fiber 11 and an FBG unit 12 is provided. The FBG unit 12 in the optical fiber 11 is attached to the support member 3. Specifically, the FBG unit 12 is attached to the support member 3 so that the axial length changes when the acceleration is applied to the measurement target M and the support member 3 bends between both ends thereof. It has been. For example, when the support member 3 is formed of a plate-like member, the two FBG portions 12 are arranged in the axial direction of each FBG portion 12 (the left-right direction in FIG. 1A) and the axial direction of the support member 3. (The left-right direction in FIG. 1A) are fixed to the surface of the support member 3 so as to be parallel to each other.

As shown in FIG. 1, one end of the optical fiber 11 is provided so as to be connectable to the control device CD. Specifically, a coupler or the like is provided at one end of the optical fiber 11, and if this coupler or the like is connected to the control device CD, incident light having a predetermined intensity can be supplied from the control device CD to the optical fiber 11. In addition, the control device CD can receive the reflected light of the incident light reflected by the FBG unit 12.
The control device CD has a function of measuring the frequency or wavelength of the received reflected light and calculating the deformation (distortion) of the FBG unit 12 based on the measured frequency or wavelength. In other words, the control device CD has a function of calculating the distortion of the FBG unit 12, that is, the deformation of the support member 3 based on the frequency shift or wavelength shift of the reflected light.

For example, an optical spectrum analyzer or the like can be used for the control device CD, but it is sufficient if it has a function of detecting the frequency and wavelength of the reflected light.
Further, the optical fiber 11 may be connected not only at one end but also at the other end to the control device CD. In this case, not only the reflected light but also the transmitted light transmitted through the FBG unit 12 can be measured. Therefore, based on the frequency shift or wavelength shift of the transmitted light and / or reflected light, the FBG unit 12 It is also possible to calculate the distortion, that is, the deformation of the support member 3.

(Description of acceleration measurement by the acceleration sensor 1 of the present embodiment)
Next, acceleration measurement by the acceleration sensor 1 of the present embodiment will be described with reference to FIGS. 1 and 2.
In FIG. 2, the sensor unit 10 is omitted for easy understanding of the movement of the support member 3 and the like.
In the following description, the case where the distortion of the FBG unit 12 is detected based on the frequency shift of the reflected light will be described. However, the distortion of the FBG unit 12 can also be detected based on the change in the wavelength of the reflected light. Needless to say.

  As shown in FIG. 1, the acceleration sensor 1 of this embodiment is fixed between a pair of opposing wall surfaces W1 and W2 in the measuring object M. Specifically, both ends of the support member 3 are fixed to the wall surfaces W1 and W2, respectively. The support member 3 is a plate-like member that can be bent only in the vertical direction in FIG. 1, and has two FBG portions 12 on one surface (the upper surface in FIGS. 1 and 2). Is provided.

  When the measuring object M moves from the state of FIG. 1 in the direction of the arrow shown in FIG. 2A, the supporting member 3 that connects the inertial member 4 and the measuring object M has elasticity. 4 cannot follow the movement of the measuring object M due to inertia. For this reason, a difference in movement acceleration occurs between them, and the support member 3 bends in the same direction (downward in FIG. 2A) between the inertia member 4 and the wall surfaces W1 and W2 of the measurement target M. Mu Then, since distortion occurs in the FBG unit 12 due to the bending of the support member 3, when light enters the optical fiber 11 from the control device CD in this state, the reflected light and / or transmitted light from the FBG unit 12 undergoes a frequency shift. Arise.

Here, when the measurement object M (that is, the object having the wall surfaces W1 and W2) moves in the same direction at the same speed, the frequency shifts of the two FBG units 12 show almost the same tendency. Specifically, when the frequency shift in one FBG unit 12 shifts in the direction in which the frequency increases, the frequency shift in the other FBG unit 12 also shifts in the direction in which the frequency increases.
Therefore, based on the frequency shift of the two FBG units 12, the control device CD can determine that the translational acceleration is applied to the measurement object M.

In addition, when the measurement object M (that is, the object having the wall surfaces W1 and W2) moves from the state of FIG. 1 so as to rotate around the inertia member 4 as shown in FIG. 4 cannot follow the movement of the measuring object M due to inertia. For this reason, a difference in movement acceleration occurs between them, and the support member 3 bends between the inertia member 4 and the wall surfaces W1 and W2 of the measuring object M, and distortion occurs in the FBG portion 12. At this time, unlike the case where translational acceleration is applied, the support member 3 bends in the opposite direction, so the frequency shifts of the two FBG portions 12 show opposite tendencies. Specifically, the frequency shift in one FBG unit 12 shifts in the direction in which the frequency increases, while the frequency shift in the other FBG unit 12 shifts in the direction in which the frequency decreases.
Therefore, based on the frequency shift of the two FBG units 12, the control device CD can determine that the rotational acceleration is applied to the measuring object M.

  In addition, when the rotation center of the measuring object M and the center of the inertia member 4 are misaligned, even if rotational acceleration is applied to the measuring object M, the support member 3 is similar to the case where translational acceleration is applied. It bends in the same direction between the inertia member 4 and the wall surface W1, W2 of the measuring object M. However, when rotational acceleration is applied, there is a difference in the distance from the center of rotation to the two FBG units 12. For this reason, even if the support member 3 bends in the same direction at the position where the two FBG portions 12 are provided, a difference occurs in the amount of bending, and a difference occurs in the amount of frequency shift. Therefore, if the frequency shift amounts in the two FBG units 12 are compared, even if the rotation center of the measurement target M and the center of the inertia member 4 are misaligned, it is determined that rotational acceleration is applied to the measurement target M. Judgment can be made. And if the difference of the amount of frequency shifts is computed, the distance from the inertia member 4 to the rotation center of the measuring object M can also be computed.

  As described above, if the acceleration sensor 1 of the present embodiment is used, even one acceleration sensor 1 can measure both the translational acceleration and the rotational acceleration of the measurement target M to which the acceleration sensor 1 is attached. It is.

(Regarding the location of the FBG 12)
The mounting method for attaching the two FBG parts 12 to the support member 3 is not particularly limited. However, as described above, when the support member 3 is formed of a plate-like member, the two FBG parts 12 are attached. 12 is preferably provided so that its axial direction coincides with the axial direction of the plate-like member. In this case, since the movement of the support member 3 is limited in a direction intersecting the surface thereof, if the normal direction of the surface of the support member 3 and the direction in which the acceleration is to be measured coincide with each other, the acceleration in a predetermined direction is obtained. It can be measured with high accuracy.

  In the above example, the case where the two FBG portions 12 are attached to one surface of the support member 3, that is, the same surface of the support member 3 has been described. However, the two FBG portions 12 do not necessarily have to be provided on the same side surface, and may be provided on the opposite side surface. In this case, the frequency shift tends to be opposite to the above example. That is, when the translational acceleration is applied to the measurement target M, the frequency shift of the two FBG units 12 shows an opposite tendency, and when the rotational acceleration is applied to the measurement target M, the frequency shift of the two FBG units 12 is It shows the same tendency.

Furthermore, the two FBG parts 12 should just be attached so that the inertia member 4 may be pinched | interposed.
However, when the distance from each end of the support member 3 to the inertia member 4 is the same, that is, when the support member 3 is provided on the measurement object M so as to be symmetric with respect to the inertia member 4. Preferably, the two FBG portions 12 are also provided so as to be symmetric with respect to the inertia member 4. In this case, since the acceleration is calculated based on the strain generated at a symmetrical position with the inertia member 4 interposed therebetween, there is an advantage that the translational acceleration and the rotational acceleration of the measuring object M can be accurately measured. In some cases, optical signal processing can be simplified.

(About the support member 3 and the inertia member 4)
Further, the bending rigidity of the support member 3 is not particularly limited, and the mass of the inertia member 4 is not particularly limited. These may be set appropriately according to the maximum acceleration applied to the measurement target M and the accuracy of measuring the acceleration.
Of course, the shape and material of the support member 3 are not limited, but it is preferable to use spring steel or phosphor bronze as a material so that the vibration mode is a simple shape because accuracy can be improved.

  Similarly, the mass of the inertia member 4 is not particularly limited as long as the mass is such that the support member 3 can be deformed such as bending or bending when acceleration is applied to the measurement target M. Of course, the shape and material of the inertia member 4 are not limited, but it is preferable to use a material having a high density as a material to obtain a shape having a large moment of inertia because accuracy can be improved.

  For example, if the measurement target M is a vehicle or the like, a phosphor bronze plate material having a length between both ends of about 50 to 100 mm and a thickness of about 0.2 to 0.5 mm is used as the support member 3, and inertia is achieved. If a mass of about 6 g (material: lead) or the like is used as the member 4, it is possible to accurately measure translational acceleration and rotational acceleration applied to the measurement target M, and to obtain advantages such as miniaturization of the sensor.

(Acceleration sensor 1 of other embodiment)
Even if the measurement object M does not have the pair of wall surfaces W1 and W2 as described above, a case 2 having a pair of wall surfaces 2a and 2b is provided as shown in FIG. The support member 3 may be disposed in 2 and the case 2 may be attached to the measurement object M. Then, as in the case described above, the acceleration of the measuring object M can be measured.

  In particular, when the support member 3 or the like is enclosed in the case 2, the acceleration sensor 1 of the present embodiment can be handled as an integrated sensor set. In this case, it is possible to prevent the optical fiber 11 of the sensor unit 10 from being damaged due to interference with other members, thereby improving the handleability of the acceleration sensor 1 of the present embodiment. And since the acceleration sensor 1 can be installed in the measuring object M only by attaching the case 2 to the measuring object M, the work man-hour for attaching the acceleration sensor 1 of this embodiment to the measuring object M can also be reduced.

In the above example, the case where the sensor unit 10 uses two optical fibers 11 including the FBG unit 12 has been described.
However, as shown in FIG. 3A, two FBG portions 12 may be provided in one optical fiber 11, and each FBG portion 12 may be provided at a position where the inertia member 14 is sandwiched in the support member 3. In this case, since the control device CD can be reduced, it is preferable because the equipment necessary for measurement using the acceleration sensor 1 can be reduced in size and simplified.

  Further, as shown in FIG. 3B, a fixing member 5 having little elasticity is fixed between a pair of wall surfaces W1, W2 of the measuring object M, and a pair of support members 3, 3 are provided on the fixing member 5. The FBG portions 12 and 12 of the sensor portion 10 may be attached to the pair of support members 3 and 3, respectively.

  In this case, the pair of support members 3 and 3 are formed of an elastic material, and the base ends of the pair of support members 3 and 3 are fixed to the fixing member 5 so that the distal ends thereof are free ends. That is, the pair of support members 3, 3 can be swung with their base ends as fulcrums (in other words, the pair of support members 3, 3 can bend). 3 is fixed to the fixing member 5. For example, in FIG. 3B, the pair of support members can swing along the axial direction of the fixing member 5, that is, the normal direction of the pair of wall surfaces W1 and W2 (the left-right direction in FIG. 3). 3 and 3 are fixed. And the inertia member 4 is provided in the front-end | tip of a pair of support members 3 and 3, respectively. Then, as in the case where the support member 3 is provided between the pair of wall surfaces W1 and W2 (see FIG. 1), when the acceleration of the measurement target M occurs, the pair of support members 3 and 3 are bent and deformed. If this deformation is measured based on the frequency shift of the two FBG portions 12 provided on the pair of support members 3 and 3, it can be determined whether the acceleration of the measuring object M is a translational acceleration or a rotational acceleration. be able to.

  In particular, when the central axes of the pair of support members 3 and 3 are disposed on the same reference plane and swing along the reference plane, the two FBG portions 12 and 12 are arranged. Are preferably fixed to the pair of support members 3 and 3 so that their axial directions are parallel to the reference plane. In this case, since the deformation of the pair of support members 3 and 3 is limited to the direction along the reference surface, if the surface direction of the reference surface is parallel to the direction in which acceleration is to be measured, a predetermined direction, That is, it is possible to accurately measure the acceleration generated along the surface direction of the reference surface.

  When the structure shown in FIG. 3B is used, an advantage that the degree of freedom in designing the acceleration sensor 1 is higher than that in the structure shown in FIG.

  The acceleration sensor of the present invention is suitable for measuring acceleration and vibration of devices and structures such as electric vehicles that generate electrical noise.

DESCRIPTION OF SYMBOLS 1 Acceleration sensor 3 Support member 4 Inertial member 5 Fixed member 10 Sensor part 11 Optical fiber 12 FBG part M Measurement object

Claims (7)

A sensor for measuring acceleration of a measurement object,
A support member formed of an elastic material, both ends of which are fixed to the measurement target;
An inertia member provided in the middle between both ends of the support member;
A sensor unit attached to the support member,
The sensor unit is
It has two FBG parts with fiber Bragg gratings formed on the optical fiber,
The two FBG parts are
An acceleration sensor, which is attached to a position where the inertia member of the support member is sandwiched so that both axial directions are parallel to each other. The two FBG parts are
The acceleration sensor according to claim 1, wherein the acceleration sensor is provided so as to be symmetrical with respect to the inertia member. The support member is formed of a plate-shaped member;
The two FBG parts are
3. The acceleration sensor according to claim 1, wherein each FBG portion is fixed to a surface of the support member so that an axial direction of each FBG portion and an axial direction of the support member are parallel to each other. . A sensor for measuring acceleration of a measurement object,
A fixing member fixed to the measurement object;
A pair of support members formed of an elastic material, the base end of which is fixed to the fixing member such that the tip is a free end;
A pair of inertia members provided at the tips of the pair of support members;
A sensor unit attached to the pair of support members,
The pair of support members are
Provided so as to be symmetric with respect to the fixing member,
The sensor unit is
It has two FBG parts with fiber Bragg gratings formed on the optical fiber,
The two FBG parts are
An acceleration sensor, wherein the acceleration sensor is attached to the pair of support members so that both axial directions are parallel to each other. The two FBG parts are
The acceleration sensor according to claim 4, wherein the acceleration sensor is provided so as to be symmetrical with respect to the fixing member. The pair of support members are formed by plate-like members,
The pair of support members are
The central axes of the pair of support members are disposed on the same reference plane and are oscillated along the reference plane.
The two FBG parts are
6. The acceleration sensor according to claim 4, wherein each FBG portion is fixed to the pair of support members so that axial directions of the FBG portions are parallel to the reference plane. The sensor unit is
The acceleration sensor according to any one of claims 1 to 6, wherein two fiber Bragg gratings are formed on one optical fiber to form the two FBG portions.

Images