JPH07113642A - Vibrating gyro - Google Patents

Abstract

PURPOSE:To provide a vibrating gyro, in which the accuracy of detection of angular velocity does not depend upon the solid angular arrangement of an element for excitation and an element for detection excessively. CONSTITUTION:A vibrator consists of a disk composed of a piezoelectric body 115 and a constant-modulus body, and is supported at a center. The progressive waves of transverse vibrations are excited by using AC voltage having different phase of 90 deg. in the disk. Biaxes on a plane parallel with the disk are used as the detecting axes of angular velocity, Coriolis force applied to elliptically vibrated vibrators is converted into charges by a piezoelectric effect respectively, and outputs detected from two electrodes formed around an exciting section are synchronously detected 118, thus computing the angular velocity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angular velocity sensor used, for example, for controlling the attitude of a vehicle and calculating the traveling direction.

[0002]

2. Description of the Related Art As a conventional example, for example, Japanese Patent Application Laid-Open No. 61-7.
There is an angular velocity sensor disclosed in Japanese Patent No. 7712. FIG.
Shows a basic principle diagram of this conventional vibration type angular velocity sensor. Reference numerals 1301 and 1302 denote detection elements and 130
Reference numerals 3 and 1304 denote excitation elements. Each element is composed of a piezoelectric bimorph, and two sets of an excitation element and a detection element form a tuning fork. In practice, an AC voltage is applied to the excitation element near the root of the tuning fork to vibrate the detection element, and the Coriolis force applied perpendicularly to the surface of the detection element is detected to determine the angular velocity.

Conventionally, various gyroscopes (hereinafter abbreviated as gyros) have been used as sensors for detecting angular velocity.
Is being developed. The types are roughly classified into a mechanical type coma gyro, a fluid type gas rate gyro, a vibration gyro using vibration of a tuning piece / tuning fork, an optical fiber optic gyro and a ring laser gyro. The optical gyro detects the Sagnac effect, and the others use the Coriolis force, which is a manifestation of the law of conservation of angular momentum of the rotating body, to detect the angular velocity, and the accuracy, price, and size are taken into consideration depending on the intended use. Sensor is selected.

In automobiles, it is used for chassis system control, navigation system azimuth calculation, etc., but the yaw direction (vertical line It is often the angular velocity (ie yaw rate) of rotation in a plane horizontal to the centered ground. The detection purpose is, for example, four-wheel steering (4W
In the case of chassis control such as S), the yaw rate is fed back to the control system as one of the attitude information of the vehicle to improve the attitude control performance. In the case of a navigation system, the yaw rate is integrated over time. This is to calculate the turning angle of the vehicle. The angular velocity sensor normally used for in-vehicle use is a piezoelectric vibrating gyro and an optical fiber gyro. The optical gyro has already been put into practical use as in-vehicle use as a high-precision application, and the vibrating gyro as an inexpensive gyro.

[0005]

However, when focusing on the vibration gyro, in order to detect the angular velocity by using the Coriolis force, the excitation and detection elements (for example, piezoelectric bimorph) are arranged orthogonally as in the conventional example. Will be required. In order to improve the detection accuracy of angular velocity, it is required to create a sensor while precisely controlling the mounting angle of the excitation and detection elements three-dimensionally regardless of tuning fork type or tuning piece type. In order to secure the predetermined accuracy of, there is a problem that an assembly technology with extremely high accuracy is required. Further, since the three-dimensional arrangement of the elements is important, there is a limit to miniaturization of the elements, and there is a problem that the multi-axis cannot be easily achieved.

The present invention has been made in view of the above problems, and an object thereof is to provide a vibrating gyroscope whose angular velocity detection accuracy does not depend on the three-dimensional arrangement of the excitation element and the detection element.

[0007]

In order to solve the above-mentioned problems, the present invention provides, as a first means, an axisymmetric structure with respect to a first axis which is composed of a composite of materials exhibiting a piezoelectric effect and which passes through the center and is perpendicular to the plane. A vibrating gyroscope comprising a supported circular flat plate vibrating body and a first electrode formed on the vibrating body in axial symmetry about a first axis.

As a second means, a flat plate vibrating body composed of a composite of materials exhibiting a piezoelectric effect and supported axially symmetrically with respect to a first axis in a plane passing through the center, and a line with respect to the first axis. The vibrating gyroscope includes a first electrode symmetrically formed on the vibrating body and a second electrode formed on the vibrating body in an area outside the first electrode in line symmetry with respect to the first axis.

[0009]

According to the first means, the circular plate vibrating body is excited by the first electrode formed on the surface of the disk so as to cause the strain vibration consisting of the traveling wave of the lateral vibration. When a rotation is applied around an axis within a disk plane perpendicular to the first axis, the excited strain vibration changes, so that the angular velocity can be detected by detecting the amount of fluctuation on the disk that is the vibrating body. After all, since the excitation unit and the detection unit are both arranged on the same plane, it is possible to prevent the angular velocity output from depending on the three-dimensional arrangement of the excitation unit and the detection unit.

Further, according to the second means, the first electrode excites the strain vibration of the longitudinal vibration in the flat vibrator.
When the rotation around the first axis is applied, the strain vibration excited in the region of the second electrode of the vibrating body changes, so that the angular velocity can be detected by detecting the variation amount on the flat plate which is the vibrating body. After all, since both the excitation unit and the detection unit are arranged on the same plane, it becomes possible to prevent the angular velocity output from being dependent on the three-dimensional arrangement of the excitation unit and the detection unit as in the first means. .

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a block diagram showing an electrical configuration of a vibrating gyroscope according to a first embodiment of the present invention. In FIG. 1, 101 is an oscillation circuit and 102 is a phase adjustment circuit. Reference numerals 103 to 110 are excitation electrodes, 111 to 114 are detection electrodes, and 115 is a disk-shaped vibrating body made of a piezoelectric body and a constant elastic metal. Reference numerals 116 and 117 are differential amplifier circuits, 118 and 119 are synchronous detection circuits, and 120 and 12.
1 is an output circuit. The structure of the vibrating body of the vibrating gyroscope is as shown in FIG. In FIG. 2, (a) is a top view and (b) is a side view. Reference numeral 21 denotes a piezoelectric body, 2
2 is a constant elastic metal, 23 is a pillar that supports the vibrating body 115,
24 is a pedestal. In FIG. 2 (a), the excitation electrodes formed on the piezoelectric body 21 have the same shape and are arranged axially symmetrically at an angle of 45 ° when viewed from the center of the disk, and the detection electrodes are also equal. It is arranged so that one detection electrode is included in a fan shape having an angle of 90 ° in which the two excitation electrodes are included at an angle of 90 ° when viewed from the center. Meanwhile, side view
From (b), the vibrating body 115 is composed of the piezoelectric body 21 and the constant elastic metal 22, and the vibrating body 115 is supported at the center of the disk. In addition, + -in FIG. 2A indicates the direction of polarization. That is, the polarization of the piezoelectric body is in the direction perpendicular to the disk surface,
The polarization direction is reversed every 90 °.

The operation of the vibrating gyroscope of this embodiment having the above-described structure will be described below. As shown in FIG. 1, the excitation electrodes are divided into two sets A, B of 103, 105, 107, 109 and 104, 106, 108, 110. Generally, when a voltage is applied in the polarization direction of the piezoelectric body, distortion due to compression and expansion occurs. In the case of the present embodiment, applying a constant voltage in the direction perpendicular to the disk surface using the excitation electrodes A and B corresponds to applying a voltage in the polarization direction.
If the vibrating body is composed of a single piezoelectric disk, the vibrating body will be deformed by compression and expansion in the radial direction.However, since the viscous body is bonded to the vibrating body, Displacement occurs. However, since the polarization direction is reversed every 90 °, the displacement direction is reversed every 90 ° according to the polarization direction. Therefore, when the same AC voltage is applied to the electrodes A and B by using the oscillation circuit 101, vibration in the direction perpendicular to the disk synchronized with the applied AC voltage is excited. However, the amplitude of the displacement changes depending on the position in the circumferential direction, and in this case, when the disk makes one round in the circumferential direction, the standing waves of two wavelengths are excited. In practice, the oscillator circuit 101 and the phase adjustment circuit 1
02, AC voltages of 90 ° phase different in time are applied to the electrodes A and B. In this case, the excited vibration is not a standing wave but a traveling wave in which peaks and valleys of vibration move in the circumferential direction with respect to time. Focusing on one point of the vibrating body, this mass point does not perform a single vibration perpendicular to the disc surface but an elliptical vibration, and a vibration component perpendicular to the disc surface and a parallel vibration component are induced. .

A method of detecting the angular velocity of the disk-shaped vibrating gyro in which the above vibration is excited will be described below.
In the case of the present embodiment, the detection electrodes 112 and 114 are used to detect the angular velocity around the Y axis on the disc of FIG. Since the Coriolis force is proportional to the outer product of the input angular velocity and the motion velocity of each mass point of the vibrating body, only a force parallel to the disc is generated at the mass point on the X axis. However, the Coriolis force is generated at the mass point on the Y axis in such a manner that the amplitude of the elliptical vibration is uniformly large or small. Coriolis force is generated in the form of the combination of the above two examples for the mass point at an arbitrary position. Now electrode 112 and electrode 1
Since 14 has a line-symmetrical shape with respect to the X-axis, Coriolis forces in opposite directions are generated at the mass points located at axially symmetrical positions. Electric charges are generated in the detection electrodes 112 and 114 in proportion to the displacement of the piezoelectric body on which the electrodes are formed. Therefore, when the input angular velocity is zero, equal electric charges in proportion to the amplitude of the excited elliptical vibration are generated. When the angular velocity is applied, a component proportional to the Coriolis force is generated in antiphase. Therefore, if the differential amplifier circuit 117 differentially amplifies the outputs of both electrodes, only an output proportional to the angular velocity around the Y axis can be obtained. However,
Since the excited vibration is a sine wave, the differential amplifier circuit 11
The output of 7 also becomes a sine wave synchronized with the excitation voltage. Since the angular velocity is proportional to the output amplitude of the differential amplifier circuit 117, the output of the oscillation circuit 101 is used for smoothing by the synchronous detection circuit 119, and the output circuit 121 amplifies it to a predetermined output voltage to output the final angular velocity output. Will be obtained.

When an angular velocity is applied around the X axis, the detection electrodes 111 and 113 are used in the same manner, and the differential amplifier circuit 116 extracts only the component relating to the Coriolis force. The output of the oscillator circuit 101 is used as the output of the synchronous detection circuit 11
The final angular velocity output is obtained by smoothing at 8, and then amplifying to a predetermined output voltage at the output circuit 120. When rotation is applied to both X-axis and Y-axis at the same time,
Each affects the detection unit of the other axis. However, the output due to the influence of other axes is 90% of the desired angular velocity due to the electrode arrangement for detection.
Since the phases appear out of phase, the synchronous detection circuit 118,
It can be removed by 119 and no problem occurs. Further, it has no sensitivity to rotation about the Z axis perpendicular to the disk surface, as is apparent from the relationship between the motion direction of the vibrating body and the axial direction of the angular velocity.

As described above, in the first embodiment, since the circular flat plate vibrating body is used and the traveling wave of the lateral vibration is adopted for the vibration, the exciting section and the detecting section can be formed on the same plane.
Further, since the disk is adopted as the shape of the vibrating body, it is possible to simultaneously measure the rotational angular velocities about the two axes in the disk plane.

In the first embodiment, the vibrating body is constructed by laminating the piezoelectric body and the constant elastic metal one by one, but as shown in FIG. 3, the two piezoelectric bodies and the constant elastic metal are laminated (piezoelectric). Bimorph) may be used. Further, in this embodiment, the circular vibrating body has a structure in which it is supported only on one side at the center of the disc, but it may have a structure in which it is supported on both sides as shown in FIG. Further, since the vibration of the disk is attenuated in amplitude in the radial direction from the excitation electrode, the position where the vibration of the disk becomes zero (node,
The vibrating body may be supported by, for example, a node circle. As an example, FIG. 5 shows a sectional view when the circumference of the vibrating body is a node circle. Further, in the present embodiment, the detection electrode had a shape in which a circle having a constant width concentric with the center of the disk was cut at an angle of 90 °.
The angle may be other than 90 ° as shown in FIG. However, the shapes of the two detection electrodes forming a set need to be line-symmetric with respect to the axis within the disc that is orthogonal to the rotation axis to be detected and that passes through the center of the disc. Further, in this embodiment, the traveling wave excited in the vibrating body has two wavelengths in one round, but there is no problem if the number of wavelengths is a power of two. Further, although the detection electrode is used in this embodiment, as shown in FIG. 7, the detection electrode is omitted and only the excitation electrode is used, and the displacement due to the Coriolis force affects the oscillation circuit of the vibrating body (for example, the piezoelectric body). It is also possible to detect it from the change amount of the machine arm current).

(Embodiment 2) Next, a second embodiment of the present invention will be described. FIG. 8 is a block diagram showing the electrical configuration of this embodiment. In FIG. 8, 81 is an oscillation circuit,
Reference numeral 82 is an excitation electrode, 83 and 84 are detection electrodes, 85 is a vibrating body made of a piezoelectric body and a constant elastic metal, 86 is a differential amplifier circuit, 87 is a synchronous detection circuit, and 88 is an output circuit. The structure of the vibrating body of the vibrating gyroscope is as shown in FIG.
In FIG. 9, (a) is a side view and (b) is a top view. The vibrating body 85 is composed of the piezoelectric body 93 and the constant elasticity metals 94, 95
The excitation part is composed of only a piezoelectric material, and the detection part is composed of a piezoelectric material and an elastic material bonded together. The piezoelectric body is a rectangular thin plate elongated in the direction perpendicular to the angular velocity detection axis, and the polarization is uniform in the direction perpendicular to the plane of the thin plate. Further, an electrode is formed on the entire back surface and is supported by a pedestal 92 by a pillar 91 at the center of the vibrating body.

The operation of the vibrating gyro of the present embodiment having the above-described structure will be described below. When a sine wave voltage is applied to the excitation electrode 82 using the oscillation circuit 81, the piezoelectric body repeats compression and extension operations in the longitudinal direction from the shape and polarization direction of the piezoelectric body in synchronization with the detecting portion at the tip of the vibrating body. Drive in the longitudinal direction. Since the detection axis of the angular velocity is a straight line perpendicular to the vibration direction of the vibrating body and passing through the center of the piezoelectric flat plate, Coriolis force is generated in the detection unit in the direction perpendicular to the surface. The directions are opposite because the driving directions of the two detectors are opposite. Since the elastic body is bonded to the piezoelectric body of the detection unit,
The displacement due to the Coriolis force is converted into electric charges by the piezoelectric effect. Since the outputs of the two detectors have opposite phases, the differential amplifier circuit 86, the synchronous detection circuit 87, and the like as in the first embodiment.
The angular velocity is detected by using the output circuit 88. In this case, the piezoelectric body may be supported at both ends as shown in FIG. 10, or may be supported at the center of the flat plate.

This configuration can be expanded to a two-axis detection type as shown in FIG. In FIG. 11, (a) is a top view of the vibrating gyro, and (b) is a side view. The vibrating body is a piezoelectric body 1106 and constant elastic metals 1102, 1103, 110.
4 and 1105, the excitation part is composed of only a piezoelectric material, and the detection part is composed of a piezoelectric material and an elastic material bonded together. The piezoelectric body is a vertical combination of elongated rectangular thin plates in the direction perpendicular to the detection axis of the angular velocity, and the polarization is uniform in the direction perpendicular to the plane of the thin plates. Further, an electrode is formed on the entire back surface, and is supported by a pedestal 1108 by a column 1107 at the center of the vibrating body. The operation is exactly the same as in the above-described example, and it becomes possible to detect the biaxial angular velocities at the same time by the vibrating body made of a cross-shaped thin plate.

As described above, in the second embodiment, since the piezoelectric thin plate is independently used for the exciting part of the vibrating body, the exciting part and the detecting part can be formed on the same plane. In addition, since the elongated rectangular thin plate parallel to the plane including the rotation axis is adopted as the basic shape of the vibrating body that detects the uniaxial angular velocity, it is possible to easily detect the biaxial angular velocity on the same plane at the same time. .

In the second embodiment, a cross-shaped thin plate is selected as the vibrating body when the biaxial angular velocities are simultaneously detected, but this shape may be circular as shown in FIG. 12 or is not limited to this. Not a thing. Further, in the biaxial detection type, the vibrating body has a structure in which the vibrating body is supported only on one side at the center, but there is no problem with a structure supporting both sides. Further, in the present embodiment, the shape of the detection portion is a rectangular thin plate, but this is because the shape of the two detection portions forming a set is line symmetric with respect to the axis in the plane orthogonal to the rotation axis to be detected and passing through the vibration center. If so, no problem.

[0023]

As described above, according to the present invention, the exciting element and the detecting element of the vibration gyro can be formed on the same plane. Therefore, since the detection accuracy of the angular velocity does not depend on the three-dimensional mounting angle of the excitation and detection elements, the sensor assembly accuracy can be relaxed. Further, since it becomes possible to simultaneously detect the angular velocities about two axes orthogonal to each other on the plane, the practical effect thereof is great.

[Brief description of drawings]

FIG. 1 is a block diagram showing an electrical configuration of a vibrating gyroscope according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a vibrating body of the vibrating gyroscope according to the first embodiment of the present invention.

FIG. 3 is a diagram showing an example in which the vibrating body in the vibrating gyroscope according to the first embodiment of the present invention is configured by two piezoelectric bodies and one constant elastic metal.

FIG. 4 is a view showing an example in which a vibrating body is supported on both sides of a disc center in the vibrating gyroscope according to the first embodiment of the present invention.

FIG. 5 is a diagram showing an example in which a vibrating body is supported by the circumference of a disc in the vibrating gyroscope according to the first embodiment of the present invention.

FIG. 6 is an explanatory diagram of a shape of a detection electrode in the vibration gyro of the first embodiment of the present invention.

FIG. 7 is an explanatory diagram of an electrode configuration in the vibrating gyroscope according to the second embodiment of the present invention.

FIG. 8 is a block diagram showing an electrical configuration of a vibrating gyroscope according to a second embodiment of the present invention.

FIG. 9 is a configuration diagram of a vibrating body of a vibrating gyroscope according to a second embodiment of the present invention.

FIG. 10 is a view showing an example of a vibrating gyroscope according to a second embodiment of the present invention, in which a vibrating body is supported by a flat plate center on both sides.

FIG. 11 is a diagram showing a configuration example of a biaxial detection type vibrating body in the vibrating gyroscope according to the second embodiment of the present invention.

FIG. 12 is a configuration diagram of a biaxial detection type vibrating body in a vibrating gyroscope according to a second embodiment of the present invention.

FIG. 13 is a configuration diagram of a vibrating body of a conventional tuning fork type vibration gyro.

[Explanation of symbols]

101, 81 Oscillation circuit 102 Phase adjustment circuit 116, 117, 86 Differential amplification circuit 118, 119, 87 Synchronous detection circuit 120, 121, 88 Output circuit 103, 104, 105, 106, 107, 108,
109, 110, 71, 72, 73, 74, 75, 7
6, 77, 78, 82, 1001, 1101, 1201
Excitation electrodes 111, 112, 113, 114, 83, 84 Detection electrodes 115, 22, 31, 33, 41, 51, 79, 85,
93, 1004, 1106, 1206 Piezoelectric substance 21, 32, 42, 52, 94, 95, 1002, 10
03, 1102, 1103, 1104, 1105, 12
02, 1203, 1204, 1205 Constant elastic metal 23, 34, 43, 44, 53, 54, 91, 100
5, 1006, 1107, 1207 Support 24, 35, 45, 46, 55, 92, 1007, 10
08, 1108, 1208 Pedestal 1301, 1302 Detection element 1303, 1304 Excitation element

Claims (6)

[Claims] 1. A circular flat plate vibrating body which is composed of a composite of materials exhibiting a piezoelectric effect and which is axially symmetric with respect to a first axis passing through the center and perpendicular to a plane, and axisymmetrically with respect to the first axis. The vibrating body is provided with a first electrode, and the first electrode is used to spatially periodically change in the circumferential direction in the first axial direction, and periodically change in the circumferential direction with time. The angular velocity is detected from the strain fluctuation amount of the vibrating body generated by rotating around the second axis in the plane passing through the center of the vibrating body by exciting the vibrating body with strained vibration consisting of traveling waves A vibrating gyro that is characterized by: 2. A second electrode formed on the vibrating body in line symmetry with respect to a third axis in a plane orthogonal to the second axis and passing through the center of the vibrating body, wherein the second electrode is used. 2. The vibrating gyro according to claim 1, wherein the angular velocity is detected from a strain variation amount of the vibrating body generated by the rotation around the second axis. 3. A circular flat plate vibrating body which is composed of a composite of materials exhibiting a piezoelectric effect and is supported axially symmetrically with respect to a first axis passing through the center and perpendicular to the plane, and the vibrating body having the first axis. With respect to the first electrode, the first electrode is formed axially symmetrically, spatially periodically changes in the circumferential direction in the first axial direction and periodically in the circumferential direction with time. A first change from a strain variation amount of the vibrating body, which is generated by rotating around a second axis in a plane passing through the center of the vibrating body, by exciting the vibrating body with a strained vibration composed of a traveling wave Detecting the angular velocity, detecting the second angular velocity from the strain variation amount of the vibrating body generated by rotation around the third axis in the plane orthogonal to the second axis and passing through the center of the vibrating body. Characteristic vibration gyro. 4. The vibrating body is line-symmetrical with respect to a second axis in the plane passing through the center of the vibrating body and a third axis in the plane orthogonal to the second axis and passing through the center of the vibrating body. A third electrode and a second electrode are formed, and the first angular velocity is detected from the strain variation amount of the vibrating body generated by the rotation around the second axis using the second electrode, The vibrating gyro according to claim 3, wherein the third angular electrode is used to detect a second angular velocity from a strain variation amount of the vibrating body generated by rotation around the third axis. 5. A flat plate vibrating body which is composed of a composite of materials exhibiting a piezoelectric effect and is supported axially symmetrically about a first axis in a plane passing through the center, and the vibrating body which is line symmetrical about the first axis. A first electrode formed on the body, and a second electrode formed on the vibrating body in an area outside the first electrode in line symmetry with respect to the first axis, and the first electrode Using a second electrode to excite strain vibration that changes periodically with time in a plane in a direction perpendicular to the first axis in the region in which the second electrode of the vibrator is formed. A vibrating gyro, wherein an angular velocity is detected from a strain variation amount of the vibrating body generated by rotation of the vibrating body around the first axis. 6. A vibrating body is supported at the center by flat plates which are line-symmetric with respect to a first axis and a second axis which are orthogonal to each other in a plane passing through the center, and a first electrode is provided with the first axis. Both are formed in the vibrating body in line symmetry with respect to the second axis, and in addition to the second electrode, are formed in the vibrating body in a region outside of the first electrode in line symmetry with respect to the second axis. A third electrode is provided, and strain vibration that cyclically changes with time in the second axial direction using the first electrode is applied to a region of the vibrating body in which the second electrode is formed. Excited strain vibration that periodically changes in the first axial direction with time in the region where the third electrode of the vibrating body is formed, and using the second electrode, the first vibrating body of the vibrating body is excited. The first angular velocity is detected from the strain variation amount of the vibrating body generated by the rotation around the axis, and the third angular velocity is detected. Claim and detecting a second angular velocity from the strain variation of the vibrator generated by the rotation said second axis of said vibrating body with a pole 5
Vibration gyro described.