JP2005031097A - Apparatus for detecting both acceleration and angular velocity - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect both acceleration and angular velocity with sufficient response, especially concerning an apparatus for detecting the acceleration and the angular velocity based on force acting on an oscillator. <P>SOLUTION: The apparatus is provided with excitation means 141-143 for exciting an oscillator 130 having a mass (m) in each axial direction and force-detecting means 151-153 for detecting force acting on the oscillator in each axial direction. The detected force in each axial direction is separated into force (f) resulting from acceleration and the Coriolis force F which results from angular velocity by signal separation means 161-163. On the basis of each separated force (f), acceleration calculation means 171-173 output respective axial components αx, αy, and αz of acceleration by using the arithmetic expression f=m×α. Based on each separated Coriolis force F, angular velocity calculation means 181-183 output angular velocity ωx, ωy, and ωz around each axis by using the arithmetic expression F=2m×v×ω (v is an instantaneous speed regarding the oscillation direction of the oscillator). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an apparatus that detects both acceleration and angular velocity, and more particularly to an apparatus that detects acceleration and angular velocity based on a force acting on a vibrator.

  In the case of detecting physical quantities such as acceleration and angular velocity, conventionally, an acceleration detection device is generally used to detect acceleration, and an angular velocity detection device is generally used to detect angular velocity. As far as the applicant of the present application knows, an apparatus capable of detecting both is not practically used at the commercial level at this stage. Conventionally, a one-dimensional acceleration detection device that detects acceleration in a specific uniaxial direction and a one-dimensional angular velocity detection device that detects an angular velocity around a specific one axis are generally used. In the case of detecting these physical quantities for each component, it is common to arrange an independent detection device for each coordinate axis.

However, in recent years, there has been an increasing demand for detection devices that can accurately detect physical quantities such as acceleration and angular velocity in the automobile industry and the machine industry. In particular, there is a demand for a small detection device that can detect these physical quantities for each component of two-dimensional or three-dimensional coordinate axes. In order to meet such demand, the same inventor as the present application uses a single detection device to independently determine the acceleration in each coordinate axis direction and the angular velocity around the angular coordinate axis in the three-dimensional coordinate system. Detection techniques have been proposed. That is, the following Patent Documents 1 and 2 disclose novel detection devices that can detect acceleration and angular velocity for each coordinate axis component based on the force acting on the vibrator. The detection principle of the angular velocity in this apparatus uses the Coriolis force. That is, in the state where the angular velocity ωx around the X axis is acting on the vibrator, the vibrator is excited using the principle that when this vibrator is vibrated in the Y axis direction, Coriolis force acts in the Z axis direction. The Coriolis force acting in the Z-axis direction is detected in the state of being vibrated in the Y-axis direction by the means, and the angular velocity ωx around the X-axis is obtained indirectly based on this Coriolis force.
International Publication WO94 / 23272 JP-A-8-35981

  Although the above-described novel detection device is a relatively small device, it can detect six physical quantities such as acceleration in the X-axis, Y-axis, and Z-axis directions, and respective speeds around these axes. Device. However, in this apparatus, it is necessary to detect the force acting on the vibrator for detecting acceleration and angular velocity. That is, on the one hand, the acceleration applied from the outside is detected by detecting the force acting on the vibrator while the vibrator is kept stationary, and on the other hand, the vibrator is vibrated in a predetermined direction. In the state, the angular velocity given from the outside is detected by detecting the Coriolis force acting on the vibrator. Therefore, when performing acceleration detection, the vibrator must be kept stationary, and when performing angular velocity detection, the vibrator must be kept in vibration.

  When such a detection device is mounted and used in an automobile or industrial machine, it is usually required to detect in real time the acceleration and angular velocity that change from moment to moment. In order to detect the acceleration and the angular velocity in real time using the above-described detection device, an operation for detecting acceleration while keeping the vibrator in a stationary state and an angular velocity detection while keeping the vibrator in a vibrating state are performed. It is necessary to repeatedly perform the operation to be performed alternately. However, there is a limit to the mechanical responsiveness of the vibrator, and it takes some time to oscillate the vibrator in the stationary state or to make the vibrator in the vibrating state stationary. For this reason, if the operation for detecting the acceleration and the angular velocity in real time is performed, there arises a problem that sufficient responsiveness cannot be obtained.

  Accordingly, an object of the present invention is to provide a detection device that can detect both acceleration and angular velocity with sufficient responsiveness.

  The basic concept of the present invention is that when detecting acceleration in the first axis direction and angular velocity around the second axis in a three-dimensional coordinate system, the vibrator has a mass, and the vibrator is connected to the three-dimensional coordinate system. In the third axial direction, the excitation means for oscillating at a sufficiently high frequency distinguishable with respect to the frequency of the acceleration and angular velocity to be detected, and the force in the first axial direction applied to the vibrator are detected. Force detection means, signal separation means for separating a bias component and an amplitude component for a detection signal obtained by the force detection means, acceleration calculation means for obtaining acceleration in a first axial direction based on the bias component, By providing an angular velocity calculation means for obtaining an angular velocity about the second axis based on the amplitude component, it is possible to detect both acceleration and angular velocity.

  In the detection apparatus according to the present invention, force acting on the vibrator is used for both acceleration detection and angular velocity detection. According to the basic principle of the detection operation in this detection device, in order to detect the acceleration, it is only necessary to keep the vibrator stationary and detect the force acting on the vibrator at that time, and to detect the angular velocity. The vibrator may be kept in a vibrating state and the force acting on the vibrator at that time may be detected. Based on this basic principle, the inventor of the present application initially assumes that the acceleration detection in which the vibrator is in a stationary state and the angular velocity detection in which the vibrator is in a vibration state are separately and independently performed. It was.

  However, the present inventor has realized that acceleration detection and angular velocity detection can be performed simultaneously. Now, for example, acceleration in a certain axial direction and angular velocity around a certain axis act simultaneously, and this acceleration and angular velocity act on the vibrator vibrating in a predetermined direction in the same direction. Suppose that it is of the nature to make it. In this case, the force acting on the vibrator is a combined force of a component caused by acceleration and a component caused by angular velocity. If the resultant force can be separated into a component caused by acceleration and a component caused by angular velocity, acceleration and angular velocity can be detected simultaneously.

  Such separation is possible when the vibration frequency of the vibrator is sufficiently higher than the frequency of the acceleration and angular velocity to be detected. That is, under such conditions, the component caused by acceleration is synthesized as a bias component, and the component caused by angular velocity is synthesized as an amplitude component. Therefore, if the resultant combined force is separated into a bias component and an amplitude component, it is possible to independently obtain a component caused by acceleration and a component caused by angular velocity.

(1) According to a first aspect of the present invention, there is provided an apparatus for detecting an acceleration in a first axial direction and an angular velocity around a second axis in a three-dimensional coordinate system.
A vibrator with mass,
Excitation means for oscillating the vibrator in a third axis direction in the three-dimensional coordinate system at a sufficiently high frequency distinguishable with respect to the frequency of the acceleration and angular velocity to be detected;
Force detecting means for detecting a force in the first axial direction applied to the vibrator;
For the detection signal obtained by the force detection means, signal separation means for separating the bias component and the amplitude component;
Acceleration calculation means for obtaining acceleration in the first axial direction based on the bias component;
Angular velocity calculation means for obtaining an angular velocity about the second axis based on the amplitude component;
Is provided.

(2) According to a second aspect of the present invention, there is provided an apparatus for detecting an acceleration in each axial direction of a first axis, a second axis, and a third axis and an angular velocity around each axis in a three-dimensional coordinate system.
A vibrator with mass,
First excitation means for oscillating the vibrator in a first axis direction at a sufficiently high frequency that can be identified with respect to the frequency of the acceleration and angular velocity to be detected;
Second excitation means for oscillating the vibrator in a second axis direction at a sufficiently high frequency that can be identified with respect to the frequency of the acceleration and angular velocity to be detected;
Third excitation means for oscillating the vibrator in a third axis direction at a sufficiently high frequency distinguishable with respect to the frequency of the acceleration and angular velocity to be detected;
First force detecting means for detecting a force in a first axial direction applied to the vibrator;
A second force detecting means for detecting a force in the second axial direction applied to the vibrator;
Third force detecting means for detecting a force in the third axial direction applied to the vibrator;
A first signal separation means for separating a bias component and an amplitude component for the first detection signal obtained by the first force detection means;
A second signal separation means for separating a bias component and an amplitude component for the second detection signal obtained by the second force detection means;
A third signal separation means for separating a bias component and an amplitude component for the third detection signal obtained by the third force detection means;
First acceleration calculation means for determining acceleration in the first axial direction based on a bias component for the first detection signal;
Second acceleration calculating means for obtaining acceleration in the second axial direction based on a bias component for the second detection signal;
Third acceleration calculating means for obtaining acceleration in the third axial direction based on the bias component for the third detection signal;
The first excitation means is driven to vibrate the vibrator in the second axial direction, and the first angular velocity around the third axis is obtained based on the amplitude component of the first detection signal obtained in this state. Angular velocity calculation means,
The second excitation means is driven to vibrate the vibrator in the third axial direction, and a second angular velocity around the first axis is obtained based on the amplitude component of the second detection signal obtained in this state. Angular velocity calculation means,
The third excitation unit is driven to vibrate the vibrator in the first axial direction, and a third angular velocity around the second axis is obtained based on the amplitude component of the third detection signal obtained in this state. Angular velocity calculation means,
Is provided.

(3) According to a third aspect of the present invention, there is provided an apparatus for detecting an acceleration in each axial direction of a first axis, a second axis, and a third axis and an angular velocity around each axis in a three-dimensional coordinate system.
A vibrator with mass,
First excitation means for oscillating the vibrator in a first axis direction at a sufficiently high frequency that can be identified with respect to the frequency of the acceleration and angular velocity to be detected;
Second excitation means for oscillating the vibrator in a third axis direction at a sufficiently high frequency distinguishable with respect to the frequency of the acceleration and angular velocity to be detected;
First force detecting means for detecting a force in a first axial direction applied to the vibrator;
A second force detecting means for detecting a force in the second axial direction applied to the vibrator;
Third force detecting means for detecting a force in the third axial direction applied to the vibrator;
A first signal separation means for separating a bias component and an amplitude component for the first detection signal obtained by the first force detection means;
A second signal separation means for separating a bias component and an amplitude component for the second detection signal obtained by the second force detection means;
A third signal separation means for separating a bias component and an amplitude component for the third detection signal obtained by the third force detection means;
First acceleration calculation means for determining acceleration in the first axial direction based on a bias component for the first detection signal;
Second acceleration calculating means for obtaining acceleration in the second axial direction based on a bias component for the second detection signal;
Third acceleration calculating means for obtaining acceleration in the third axial direction based on the bias component for the third detection signal;
The first excitation means is driven to vibrate the vibrator in the third axial direction, and the first angular velocity around the second axis is obtained based on the amplitude component of the first detection signal obtained in this state. Angular velocity calculation means,
The first excitation means is driven to vibrate the vibrator in the first axial direction, and based on the amplitude component of the second detection signal obtained in this state, the angular velocity around the third axis is obtained, The second excitation means is driven to obtain an angular velocity about the first axis based on the amplitude component of the second detection signal obtained in a state where the vibrator is vibrated in the third axial direction. Angular velocity calculation means,
Is provided.

(4) According to a fourth aspect of the present invention, the acceleration in the first axial direction and the angular velocity around the first axis, the acceleration in the second axial direction and the angular velocity around the second axis in the three-dimensional coordinate system In a device for detecting
A vibrator with mass,
Excitation means for oscillating the vibrator in a third axis direction in the three-dimensional coordinate system at a sufficiently high frequency distinguishable with respect to the frequency of the acceleration and angular velocity to be detected;
First force detecting means for detecting a force in a first axial direction applied to the vibrator;
A second force detecting means for detecting a force in the second axial direction applied to the vibrator;
A first signal separation means for separating a bias component and an amplitude component for the first detection signal obtained by the first force detection means;
A second signal separation means for separating a bias component and an amplitude component for the second detection signal obtained by the second force detection means;
First acceleration calculation means for determining acceleration in the first axial direction based on a bias component for the first detection signal;
Second acceleration calculating means for obtaining acceleration in the second axial direction based on a bias component for the second detection signal;
First angular velocity calculation means for obtaining an angular velocity about the second axis based on the amplitude component of the first detection signal;
A second angular velocity calculating means for obtaining an angular velocity around the first axis based on the amplitude component of the second detection signal;
Is provided.

(5) According to a fifth aspect of the present invention, in the apparatus according to the first to fourth aspects described above,
The signal separation means extracts each inflection point of the detection signal, and has a signal value obtained by averaging the signal values of these two inflection points at an intermediate position on the time axis of two adjacent inflection points. A signal obtained by obtaining points and connecting the obtained reference points is used as a bias component, and a signal corresponding to the difference between the detection signal and the bias component is used as an amplitude component.

(6) According to a sixth aspect of the present invention, in the apparatus according to the first to fourth aspects described above,
The acceleration calculation means obtains the acceleration α by applying the calculation formula f = m · α based on the detected bias component f of the force and the mass m of the vibrator.

(7) According to a seventh aspect of the present invention, in the apparatus according to the first to fourth aspects described above,
The angular velocity calculation means calculates F = 2m · v · ω based on the detected force amplitude component F, the mass m of the vibrator, and the instantaneous speed v of the vibrator estimated from the operating state of the excitation means. The angular velocity ω is obtained by applying the following equation.

(8) An eighth aspect of the present invention is an apparatus for detecting both acceleration and angular velocity,
A vibrator with mass,
Excitation means for vibrating the vibrator;
Force detecting means for detecting force applied to the vibrator based on acceleration and angular velocity;
A signal separation means for separating a detection signal obtained by the force detection means into a first signal component caused by acceleration and a second signal component caused by angular velocity;
Output means for outputting an acceleration detection value based on the first signal component and outputting an angular velocity detection value based on the second signal component;
Is provided.

(9) According to a ninth aspect of the present invention, in the apparatus according to the eighth aspect described above,
The excitation means vibrates the vibrator at a sufficiently high frequency that can be identified with respect to the frequency of the acceleration and angular velocity to be detected.

(10) According to a tenth aspect of the present invention, in the apparatus according to the eighth or ninth aspect described above,
The signal separation means separates the first signal component and the second signal component by utilizing the difference in frequency.

  In carrying out the present invention described above, the signal separation means extracts each inflection point of the detection signal, and puts the signal value of these two inflection points at an intermediate position on the time axis of two adjacent inflection points. A reference point having a signal value obtained by averaging is obtained, a signal obtained by connecting the obtained reference points is used as a bias component, and a signal corresponding to a difference between the detection signal and the bias component is used as an amplitude component. What should I do? Further, the acceleration calculation means obtains the acceleration α by applying an arithmetic expression of f = m · α based on the detected bias component f of the force and the mass m of the vibrator, and the angular velocity calculation means Is an arithmetic expression of F = 2 m · v · ω based on the detected force amplitude component F, the mass m of the vibrator, and the instantaneous velocity v of the vibrator estimated from the operating state of the excitation means. Is applied to obtain the angular velocity ω.

  As described above, according to the detection device of the present invention, the resultant force acting on the vibrating vibrator can be separated into the force caused by the acceleration and the Coriolis force caused by the angular velocity, and the acceleration and the angular velocity can be detected simultaneously. As a result, both acceleration and angular velocity can be detected with sufficient responsiveness.

<<< §1. Basic principle of angular velocity and acceleration detection >>
First, the basic principle of angular velocity detection in the detection apparatus according to the present invention will be described. The apparatus according to the present invention can detect angular velocities around two axes or three axes. Here, first, the principle of uniaxial angular velocity detection will be briefly described. FIG. 1 is a diagram showing the basic principle of an angular velocity detection device disclosed on page 60 of the magazine “THE Invention”, vol. 90, No. 3 (1993). Consider an XYZ three-dimensional coordinate system in which a prismatic vibrator 110 is prepared and X, Y, and Z axes are defined in the directions shown in the figure. In such a system, it is known that the following phenomenon occurs when the vibrator 110 is rotating at an angular velocity ω with the Z axis as a rotation axis. That is, when a vibration U that causes the vibrator 110 to reciprocate in the X-axis direction is applied, a Coriolis force F is generated in the Y-axis direction. In other words, if the vibrator 110 is rotated about the Z axis while the vibrator 110 is vibrated along the X axis in the figure, a Coriolis force F is generated in the Y axis direction. This phenomenon is a dynamic phenomenon that has long been known as the Foucault pendulum. The generated Coriolis force F is
F = 2m ・ v ・ ω
It is represented by Here, m is the mass of the vibrator 110, v is the instantaneous speed of vibration of the vibrator 110, and ω is the instantaneous angular speed of the vibrator 110.

  The uniaxial angular velocity detection device disclosed in the aforementioned magazine detects the angular velocity ω by utilizing this phenomenon. That is, as shown in FIG. 1, the first piezoelectric element 111 is on the first surface of the prismatic vibrator 110, and the second piezoelectric element 112 is on the second surface orthogonal to the first surface. Are attached respectively. As the piezoelectric elements 111 and 112, plate-shaped elements made of piezoelectric ceramic are used. The piezoelectric element 111 is used to apply the vibration U to the vibrator 110, and the piezoelectric element 112 is used to detect the generated Coriolis force F. That is, when an AC voltage is applied to the piezoelectric element 111, the piezoelectric element 111 repeatedly expands and contracts and vibrates in the X-axis direction. This vibration U is transmitted to the vibrator 110, and the vibrator 110 vibrates in the X-axis direction. As described above, when the vibrator 110 itself rotates at the angular velocity ω with the Z axis as the central axis in a state where the vibration U is applied to the vibrator 110, the Coriolis force F is generated in the Y axis direction due to the phenomenon described above. Since the Coriolis force F acts in the thickness direction of the piezoelectric element 112, a voltage V proportional to the Coriolis force F is generated on both surfaces of the piezoelectric element 112. Therefore, by measuring this voltage V, the angular velocity ω can be detected.

  The conventional angular velocity detection device described above is for detecting an angular velocity around the Z axis, and cannot detect an angular velocity around the X axis or the Y axis. In the detection apparatus according to the present invention, as shown in FIG. 2, for a predetermined object 120, an angular velocity ωx around the X axis, an angular velocity ωy around the Y axis, and an angular velocity ωz around the Z axis in the XYZ three-dimensional coordinate system. Can be detected separately and independently. The basic principle will be described with reference to FIGS. Now, it is assumed that the vibrator 130 is placed at the origin position of the XYZ three-dimensional coordinate system. In order to detect the angular velocity ωx around the X-axis of the vibrator 130, as shown in FIG. 3, the Coriolis force Fy generated in the Y-axis direction when a vibration Uz in the Z-axis direction is applied to the vibrator 130. Can be measured. The Coriolis force Fy is a value proportional to the angular velocity ωx. Further, in order to detect the angular velocity ωy around the Y axis of the vibrator 130, as shown in FIG. 4, when the vibration Ux in the X axis direction is applied to the vibrator 130, the Coriolis generated in the Z axis direction. What is necessary is just to measure force Fz. The Coriolis force Fz is a value proportional to the angular velocity ωy. Further, in order to detect the angular velocity ωz around the Z-axis of the vibrator 130, as shown in FIG. 5, when the vibration Uy in the Y-axis direction is applied to the vibrator 130, the Coriolis generated in the X-axis direction. What is necessary is just to measure force Fx. The Coriolis force Fx is a value proportional to the angular velocity ωz.

  In the end, in order to detect the angular velocity ωx around the X axis, the angular velocity ωy around the Y axis, and the angular velocity ωz around the Z axis in the XYZ three-dimensional coordinate system, as shown in FIG. An X-axis direction excitation unit 141 that provides a vibration Ux of Y, a Y-axis direction excitation unit 142 that provides a vibration Uy in the Y-axis direction, a Z-axis direction excitation unit 143 that provides a vibration Uz in the Z-axis direction, and the vibrator 130. X-axis direction force detecting means 151 for detecting the acting C-oligo force Fx in the X-axis direction, Y-axis direction force detecting means 152 for detecting the C-oriolis force Fy in the Y-axis direction, and Z-axis for detecting the Coriolis force Fz in the Z-axis direction. Each of the directional force detection means 153 may be prepared.

  On the other hand, the detection principle of acceleration is simpler. That is, when an acceleration α in a predetermined direction acts on a stationary vibrator (functioning as a weight having a simple mass m), a force f of f = m · α acts in the same direction as the acceleration α. It will be. Therefore, if the axial forces fx, fy, and fz acting on the stationary vibrator 130 are detected, the accelerations αx, αy, and αz in the axial directions can be detected by calculation using the mass m. .

  Eventually, in order to detect the acceleration αx in the X-axis direction, the acceleration αy in the Y-axis direction, and the acceleration αz in the Z-axis direction in the XYZ three-dimensional coordinate system, as shown in FIG. An X-axis direction force detection unit 151 that detects an axial force fx, a Y-axis direction force detection unit 152 that detects a force fy in the Y-axis direction, and a Z-axis direction force detection unit 153 that detects a force fz in the Z-axis direction. All you have to do is prepare them.

  FIG. 6 shows the components of the three-dimensional angular velocity detection device as a block diagram, and FIG. 7 shows the components of the three-dimensional acceleration detection device as a block diagram. It can be seen that includes the latter configuration. That is, if the excitation means 141, 142, and 143 for each axial direction are further added to the acceleration detection device shown in FIG. 7, the angular velocity detection device shown in FIG. 6 is obtained, and the angular velocity detection shown in FIG. The device also functions as the acceleration detection device shown in FIG.

  However, since both angular velocity and acceleration are detected in the form of forces acting in the respective axial directions, if both the angular velocity and the acceleration are detected by a single detection device, the detected force includes the angular velocity component and Both acceleration components are included. As described above, the force caused by the angular velocity is a Coriolis force (having a magnitude of F = 2 m · v · ω) generated only when the vibrator is vibrated in a predetermined direction. In this specification, This is indicated by a capital letter “F”. In FIG. 6, Fx, Fy, and Fz that are the detection targets of the force detection means 151, 152, and 153 are all Coriolis force generated due to the angular velocity. On the other hand, the force due to acceleration is a force (f = m · α) that is generated regardless of the vibration of the vibrator, and in the present specification, this is indicated by a lowercase letter “f”. In FIG. 7, fx, fy, and fz that are the detection targets of the force detection units 151, 152, and 153 are all forces caused by acceleration. In a state in which both the angular velocity and the acceleration are acting on the vibrator 130, the force detecting means 151, 152, 153 have Coriolis forces Fx, Fy, Fz caused by the angular velocity and a force fx caused by the acceleration. , Fy, and fz are detected. The problem to be solved by the present invention is how to separately detect the Coriolis force F caused by the angular velocity and the force f caused by the acceleration in such a situation.

<<< §2. Specific Detection Device Structure Suitable for the Implementation of the Present Invention >>
The basic configuration of the detection device according to the present invention is as shown in the block diagram of FIG. 6, and the present invention can be applied to any detection device as long as it has such a configuration. It is. Various examples of the specific structure of the detection apparatus having the configuration shown in the block diagram of FIG. 6 are disclosed in Patent Document 1 and Patent Document 2 described above. The present invention does not relate to a specific structure of such a detection apparatus, but relates to signal processing of a detection signal obtained from such a detection apparatus. Therefore, only an example of a specific structure of such a detection device will be described here for reference. Of course, the technical scope of the present invention is not limited to the specific structure described here.

  FIG. 8 is a perspective view of this specific detection device as viewed obliquely from above, and FIG. 9 is a perspective view of this detection device as viewed from obliquely below. In this detection device, twelve upper electrodes A1 to A8 and E1 to E4 are formed on the upper surface of a disk-shaped piezoelectric element 10, and one lower electrode B is formed on the lower surface. Here, for convenience of explanation, the origin O of the XYZ three-dimensional coordinate system is defined as the center position of the upper surface of the disk-shaped piezoelectric element 10, and the X axis and the Y axis are defined in the direction along the upper surface of the piezoelectric element 10. , The Z axis is defined in a direction vertically upward with respect to the upper surface. Therefore, the upper surface of the piezoelectric element 10 is included in the XY plane.

  The structural feature of the piezoelectric element 10 is that an annular groove 15 is formed on the lower surface as shown in FIG. In this embodiment, the annular groove 15 has a circular shape surrounding the origin O. The lower electrode B is a single electrode layer, and is formed on the entire lower surface of the piezoelectric element 10 including the inside of the annular groove 15. On the other hand, the twelve upper electrodes A1 to A8 and E1 to E4 each have a strip shape along an arc centered on the origin O, as clearly shown in the top view of FIG. The shape is axisymmetric with respect to the axis or the Y axis.

  The structure of this detection device will become more apparent with reference to FIG. FIG. 11 is a side sectional view of the detection device taken along the XZ plane. The portion of the piezoelectric element 10 where the annular groove 15 is formed has a smaller thickness than other portions and has flexibility. Here, a portion located above the annular groove 15 in the piezoelectric element 10 is referred to as a flexible portion 12, and a central portion surrounded by the flexible portion 12 is referred to as a central portion 11. A portion located on the outer periphery will be referred to as a peripheral portion 13. The relative positional relationship of these three parts is clearly shown in the bottom view of FIG. That is, the flexible portion 12 is formed in the portion where the annular groove 15 around the central portion 11 is formed, and the peripheral portion 13 is formed around the flexible portion 12.

  Here, for example, when only the peripheral portion 13 is fixed to the detection device casing and the entire detection device casing is shaken, a force based on acceleration acts on the central portion 11 due to its mass, and the flexible portion 12 is caused by this force. Will be bent. That is, the central portion 11 is supported from the periphery by the flexible portion 12 having flexibility, and can be displaced to some extent in the X-axis, Y-axis, and Z-axis directions. After all, the central portion 11 in this detection device functions as the vibrator 130 having the mass in the detection device shown in FIG. In addition to the vibrator 130, the detection apparatus shown in FIG. 6 requires excitation means 141, 142, and 143 in each axial direction and force detection means 151, 152, and 153 in each axial direction. In this specific detection device, the excitation means 141, 142, and 143 are constituted by the upper electrodes E 1 to E 4, the lower electrode B, and the piezoelectric element 10 sandwiched therebetween, and the force detection means 151. , 152 and 153 are constituted by the upper electrodes A1 to A8, the lower electrode B, and the piezoelectric element 10 sandwiched therebetween.

  Thus, in order to explain that the excitation means and the force detection means can be configured by the upper and lower electrodes and the piezoelectric element 10 sandwiched between them, first, the basic properties of the piezoelectric element 10 are confirmed. . In general, a piezoelectric element generates a polarization phenomenon by the action of mechanical stress. That is, when a stress is applied in a specific direction, a positive charge is generated on one side and a negative charge is generated on the other side. In the detection apparatus of this embodiment, a piezoelectric ceramic having a polarization characteristic as shown in FIG. That is, as shown in FIG. 13 (a), when a force in the direction extending along the XY plane is applied, a positive charge is generated on the upper electrode A side and a negative charge is generated on the lower electrode B side. On the other hand, as shown in FIG. 13B, when a force acting in the direction of contraction along the XY plane is applied, negative charges are applied to the upper electrode A side and positive charges are applied to the lower electrode B side. Each has a polarization characteristic that occurs. Conversely, when a predetermined voltage is applied to the upper and lower electrodes, mechanical stress acts on the inside of the piezoelectric element 10. That is, as shown in FIG. 13A, when a voltage is applied so as to give a positive charge to the upper electrode A side and a negative charge to the lower electrode B side, the force in the direction extending along the XY plane When a voltage is applied so as to apply a negative charge to the upper electrode A side and a positive charge to the lower electrode B side as shown in FIG. 13 (b), the direction contracts along the XY plane. The power of is generated.

  The specific detection apparatus described here constitutes each excitation means and each force detection means by utilizing such a property of the piezoelectric element. That is, each excitation means is configured using the property that stress can be generated inside the piezoelectric element by applying a voltage to the upper and lower electrodes, and when the stress acts inside the piezoelectric element, the upper and lower electrodes are charged. Each force detection means is configured by utilizing the property of generating. Hereinafter, the configuration and operation of each of these means will be described.

<X-axis direction excitation means>
Among the components shown in FIG. 6, the X-axis direction excitation means 141 includes upper electrodes E1 and E2, a part of the lower electrode B facing the upper electrodes E1 and E2, a part of the piezoelectric element 10 sandwiched between them, and an alternating current described later. And supply means. Consider a case where a positive voltage is applied to the upper electrode E1 and a negative voltage is applied to the upper electrode E2 while keeping the lower electrode B at the reference potential. Then, as shown in the side sectional view of FIG. 14, the piezoelectric element under the electrode E1 generates a stress in a direction extending in the right and left direction in the figure, and the piezoelectric element under the electrode E2 has a stress in a direction contracting in the left and right direction in the figure. (See the polarization characteristics of FIG. 13). Therefore, the entire piezoelectric element 10 is deformed as shown in FIG. 14, and the center of gravity P of the central portion 11 is displaced by Dx in the X-axis direction. Here, when the polarity of the voltage applied to the upper electrodes E1 and E2 is reversed, a negative voltage is applied to the upper electrode E1, and a positive voltage is applied to the upper electrode E2, the state below the electrode E1 is reversed, as shown in FIG. The piezoelectric element is stressed in the direction of contraction to the left and right in the figure, and the piezoelectric element below the electrode E2 is stressed in the direction of extension to the left and right of the figure. As a result, the center of gravity P of the center portion 11 is It will be displaced in the direction by -Dx.

  Therefore, the first AC voltage is applied between the lower electrode B and the upper electrode E1, and the first AC voltage is in the opposite phase between the lower electrode B and the upper electrode E2. If an AC voltage of 2 is applied, the center of gravity P will alternately generate a displacement of Dx and a displacement of -Dx along the X-axis direction, and the central portion 11 vibrates along the X-axis. Will do. As already described, the central portion 11 corresponds to the vibrator 130 in the components shown in FIG. Therefore, it is possible to apply the vibration Ux in the X-axis direction to the vibrator 130 by applying the AC voltage described above. The frequency of the vibration Ux can be controlled by the frequency of the applied AC voltage, and the amplitude of the vibration Ux can be controlled by the amplitude value of the applied AC voltage. Eventually, the X-axis direction excitation means 141 shown in FIG. 6 is constituted by the upper electrodes E1 and E2, the lower electrode B, the piezoelectric element 10, and the means for supplying an AC voltage (not shown).

<Y-axis direction excitation means>
Among the components shown in FIG. 6, the Y-axis direction excitation means 142 is illustrated with the upper electrodes E3 and E4, a part of the lower electrode B facing it, and a part of the piezoelectric element 10 sandwiched between them. And no AC supply means. The operation principle is exactly the same as the operation principle of the X-axis direction excitation means 141 described above. That is, as shown in the top view of FIG. 10, the upper electrodes E1 and E2 are arranged on the X axis, whereas the upper electrodes E3 and E4 are arranged on the Y axis. Accordingly, by supplying AC voltages whose phases are reversed to the upper electrodes E 1 and E 2, the upper electrodes E 3 and E 4 are operated according to the same principle that the center portion 11 (vibrator) can be vibrated in the X-axis direction. By supplying alternating voltages whose phases are reversed to each other, the central portion 11 (vibrator) can be vibrated in the Y-axis direction.

  That is, the vibration Uy in the Y-axis direction can be applied to the vibrator 130 by applying the AC voltage described above. The frequency of the vibration Uy can be controlled by the frequency of the applied AC voltage, and the amplitude of the vibration Uy can be controlled by the amplitude value of the applied AC voltage. After all, the upper electrodes E3 and E4, the lower electrode B, the piezoelectric element 10, and the means for supplying an AC voltage (not shown) constitute the Y-axis direction excitation means 142 shown in FIG.

<Z-axis direction excitation means>
Among the components shown in FIG. 6, the Z-axis direction excitation means 143 includes an upper electrode E1 to E4, a part of the lower electrode B facing the upper electrode E1 to E4, a part of the piezoelectric element 10 sandwiched between them, and an alternating current described later. And supply means. Consider a case where a negative voltage is applied to the upper electrodes E1 and E2 and a positive voltage is applied to the upper electrodes E3 and E4 while maintaining the lower electrode B at the reference potential. Then, as shown in the side sectional view of FIG. 15, the piezoelectric element under the electrodes E1 and E2 is subjected to stress in the direction of contraction in the left-right direction (and the direction perpendicular to the paper surface) of the figure, and the bottom of the electrodes E3 and E4 In the piezoelectric element, stress is generated in a direction extending in a direction perpendicular to the paper surface of the drawing (and in the horizontal direction of the drawing) (see the polarization characteristics in FIG. 13). Here, as is apparent from the top view of FIG. 10, the upper electrodes E <b> 1 and E <b> 2 are located outside the flexible portion 12, and the upper electrodes E <b> 3 and E <b> 4 are located inside the flexible portion 12. For this reason, when each stress as described above is generated, the entire piezoelectric element 10 is deformed as shown in FIG. 15, and the center of gravity P of the central portion 11 is displaced by Dz in the Z-axis direction. Become. Here, when the polarity of the voltage applied to the upper electrodes E1 to E4 is reversed, a positive voltage is applied to the upper electrodes E1 and E2, and a negative voltage is applied to the upper electrodes E3 and E4, the electrodes are reversed from FIG. The piezoelectric elements below E1 and E2 generate stress in the extending direction, and the piezoelectric elements below the electrodes E3 and E4 generate stress in the contracting direction. As a result, the center of gravity P of the central portion 11 is It will be displaced in the direction by -Dz.

  Therefore, the first AC voltage is applied between the lower electrode B and the upper electrodes E1 and E2, and the first AC voltage is opposite in phase with the lower electrode B and the upper electrodes E3 and E4. If the second AC voltage is applied as described above, the center of gravity P will alternately generate a displacement of Dz and a displacement of -Dz along the Z-axis direction. Will vibrate along. As already described, the central portion 11 corresponds to the vibrator 130 in the components shown in FIG. Therefore, the vibration Uz in the Z-axis direction can be applied to the vibrator 130 by applying the AC voltage described above. The frequency of the vibration Uz can be controlled by the frequency of the applied AC voltage, and the amplitude of the vibration Uz can be controlled by the amplitude value of the applied AC voltage. Eventually, the Z-axis direction excitation means 143 shown in FIG. 6 is configured by the upper electrodes E1 to E4, the lower electrode B, the piezoelectric element 10, and means for supplying an AC voltage (not shown).

<X-axis direction force detection means>
Among the components shown in FIG. 6, the X-axis direction force detecting means 151 includes upper electrodes A1 and A2, a portion of the lower electrode B facing the upper electrodes A1, A2, a portion of the piezoelectric element 10 sandwiched between them, and a later-described component. And a detection circuit. Now, what kind of phenomenon occurs when a force fx based on acceleration acts on the center of gravity P of the central portion 11 (vibrator 130) in a state where the peripheral portion 13 of the detection device is fixed to the housing. To do. First, consider a case where a force fx in the X-axis direction acts on the center of gravity P as a result of the acceleration αx in the X-axis direction being applied to the center of gravity P as shown in FIG. Due to the action of the force fx, the flexible portion 12 is bent, and deformation as shown in FIG. 16 occurs. As a result, the upper electrodes A1 and A6 arranged along the X axis extend in the X axis direction, and the upper electrodes A5 and A2 arranged along the X axis shrink in the X axis direction. Since the piezoelectric elements located below these upper electrodes have polarization characteristics as shown in FIG. 13, charges having polarities as shown in FIG. 16 are generated in each upper electrode. At this time, since the lower electrode B is a single common electrode, even if charges having a polarity of “+” or “−” are partially generated, they are canceled out, and there is no total charge generation.

  Therefore, if the difference between the charge generated in the upper electrode A1 and the charge generated in the upper electrode A2 is obtained, a force fx acting in the X-axis direction can be obtained. Of course, the force fx acting in the X-axis direction can also be obtained from the difference between the charge generated in the upper electrode A5 and the charge generated in the upper electrode A6, but the upper electrodes A5 and A6 are Z Since it is used for detecting the force fz acting in the axial direction, it is not used for detecting the force fx in the X-axis direction. In the above description, the case where the force fx acting due to the acceleration is detected is taken as an example, but the Coriolis force Fx acting due to the angular velocity can be detected in the same manner. Actually, as the force in the X axis direction acting on the center of gravity P, the force fx caused by the acceleration and the Coriolis force Fx caused by the angular velocity are equivalent, and cannot be distinguished from the instantaneously detected force.

<Y-axis direction force detection means>
Among the components shown in FIG. 6, the Y-axis direction force detecting means 152 includes upper electrodes A3 and A4, a part of the lower electrode B facing the upper electrodes A3 and A4, a part of the piezoelectric element 10 sandwiched between them, And a detection circuit. The detection principle is the same as the detection principle of the X-axis direction force detection means 151 described above. In other words, in a state where the peripheral portion 13 of the detection device is fixed to the casing, what kind of phenomenon may occur when a force fy based on acceleration is applied to the center of gravity P of the central portion 11 (vibrator 130). That's fine. As a result of the acceleration αy in the Y-axis direction being applied to the center of gravity P, when a force fy in the Y-axis direction is applied, a negative charge is generated in the upper electrode A3 and a positive charge is generated in the upper electrode A4. Therefore, if the difference between the charge generated in the upper electrode A3 and the charge generated in the upper electrode A4 is obtained, a force fy acting in the Y-axis direction can be obtained. The detection of the Coriolis force Fy acting due to the angular velocity is exactly the same.

<Z-axis direction force detection means>
Among the components shown in FIG. 6, the Z-axis direction force detecting means 153 includes upper electrodes A5 to A8, a part of the lower electrode B facing the upper electrodes A5 to A8, a part of the piezoelectric element 10 sandwiched between them, and a later-described element. And a detection circuit. Now, what kind of phenomenon occurs when a force fz based on acceleration is applied to the center of gravity P of the central portion 11 (vibrator 130) in a state where the peripheral portion 13 of the detection device is fixed to the housing. To do. First, consider a case where a force fz in the Z-axis direction acts on the center of gravity P as a result of the acceleration αz in the Z-axis direction being applied to the center of gravity P as shown in FIG. Due to the action of such a force fz, the flexible portion 12 bends and deforms as shown in FIG. As a result, the upper electrodes A1, A8, A2, and A7 disposed in the outer annular region are contracted to generate “−” charges on the upper electrode side, and the upper electrodes A5, A4, A6 disposed in the inner annular region. , A3 are elongated, so that “+” charges are generated on the upper electrode side. At this time, since the lower electrode B is a single common electrode, even if charges having a polarity of “+” or “−” are partially generated, they are canceled out, and there is no total charge generation.

  Therefore, if a difference between the sum of charges generated in the upper electrodes A5 and A6 and the sum of charges generated in the upper electrodes A7 and A8 is obtained, a force fz acting in the Z-axis direction can be obtained. Of course, the Coriolis force Fz acting due to the angular velocity can be detected in exactly the same manner.

  Here, when the polarities of the charges generated in the upper electrodes when the forces fx, fy, and fz are applied, the table shown in FIG. 18 is obtained. In the table, “0” indicates that the piezoelectric element partially expands but partially contracts, so that positive and negative are canceled out and no charge is generated as a total. As described above, since each upper electrode has a line-symmetric shape with respect to the X axis or the Y axis, charges are generated even if the force fy is applied to the upper electrode that generates charges by the action of the force fx. On the other hand, no charge is generated even if the force fx is applied to the upper electrode that generates an electric charge by the action of the force fy. Thus, in order to avoid other-axis interference, it is important to make the electrode shape line-symmetric. The table in FIG. 18 shows the polarity when the positive force + fx, + fy, + fz of each axis is applied, but the negative force -fx, -fy, -fz of each axis. When this occurs, a charge having the opposite polarity to this table appears. It can be easily understood that such a table is obtained by referring to the deformed state shown in FIGS. 16 and 17 and the arrangement of the upper electrodes shown in FIG. In addition, the magnitude of the applied force can be detected as the amount of generated charge.

  In order to detect the forces fx, fy, fz (or Coriolis forces Fx, Fy, Fz) based on such a principle, for example, a detection circuit as shown in FIG. 19 may be prepared. In this detection circuit, the Q / V conversion circuits 31 to 38 are circuits that convert the amount of charge generated in each of the upper electrodes A1 to A8 into a voltage value when the potential of the lower electrode B is set as a reference potential. From this circuit, for example, when “+” charge is generated in the upper electrode, a positive voltage (relative to the reference potential) corresponding to the amount of generated charge is output. When a negative charge is generated, a negative voltage (relative to the reference potential) corresponding to the generated charge amount is output. The voltages V1 to V8 output in this way are given to the calculators 41 to 43, and the outputs of these calculators 41 to 43 are obtained at the terminals Tx, Ty, Tz. Here, the voltage value with respect to the reference potential of the terminal Tx becomes the detection value of the force fx (or Coriolis force Fx), the voltage value with respect to the reference potential of the terminal Ty becomes the detection value of the force fy (or Coriolis force Fy), and A voltage value with respect to the reference potential is a detection value of the force fz (or Coriolis force Fz).

  It can be understood by referring to the table of FIG. 18 that the voltage values obtained at the output terminals Tx, Ty, Tz are detected values of the forces fx, fy, fz. For example, when the force fx is applied, a charge of “+” is generated in the upper electrode A1, and a charge of “−” is generated in the upper electrode A2. Therefore, V1 is positive and V2 is negative. Therefore, by calculating V1-V2 by the calculator 41, the sum of absolute values of the voltages V1 and V2 is obtained, and this is output to the terminal Tx as a detected value of the force fx. Similarly, when the force fy is applied, a charge “−” is generated in the upper electrode A3 and a charge “+” is generated in the upper electrode A4. Therefore, V3 is negative and V4 is positive. Therefore, by calculating V4-V3 by the calculator 42, the sum of absolute values of the voltages V3 and V4 is obtained, and this is output to the terminal Ty as a detected value of the force fy. When the force fz is applied, “+” charges are generated in the upper electrodes A5 and A6, and “−” charges are generated in the upper electrodes A7 and A8. Therefore, V5 and V6 are positive, and V7 and V8 are negative voltages. Therefore, the arithmetic unit 43 calculates V5 + V6-V7-V8, thereby obtaining the sum of the absolute values of the voltages V5 to V8, which is output to the terminal Tz as the detected value of the force fz.

  What should be noted here is that the detection values obtained at the output terminals Tx, Ty, and Tz do not include other-axis components. For example, as shown in the table of FIG. 18, when only the force fx is applied, no charge is generated in the upper electrodes A3 and A4 for detecting the force fy, and no detection voltage is obtained at the terminal Ty. . At this time, charges (opposite polarities) are respectively generated in the upper electrodes A5 and A6 for detecting the force fz, but the voltages V5 and V6 are added to each other in the computing unit 43 and are canceled out. No detection voltage can be obtained. Similarly, when only the force fy is applied, no detection voltage can be obtained except for the terminal Ty. Similarly, when only the force fz is applied, no detection voltage can be obtained except for the terminal Tz. In this way, the XYZ triaxial components can be detected independently.

  The specific configuration example of the detection device shown in FIG. 6 has been described above, but various other configuration examples are possible. In short, as long as the excitation unit that mechanically vibrates the vibrator 130 in the predetermined axial direction and the detection unit that can detect the force in each axial direction acting on the vibrator 130 can be realized, any configuration can be realized. You can pick it up.

<<< §3. Conventionally proposed detection operation >>>
The conventional detection operation for detecting the accelerations αx, αy, αz in the respective axis directions and the angular velocities ωx, ωy, ωz around the angular axes by the detection device as shown in FIG. The operation "is shown in the flowchart of FIG. This detection operation is a method disclosed in Patent Document 1 described above.

  First, in step S11, the detection values of the force detection means 151, 152, and 153 are obtained in a state in which no vibration is applied to the vibrator 130 (that is, the excitation means 141, 142, and 143 are not driven). This is obtained by operating the detection device shown in FIG. 6 as the acceleration detection device shown in FIG. 7, and the detection values of the force detection means 151, 152, 153 are the forces fx, fy, fz caused by the acceleration. It becomes. Since the vibrator 130 does not vibrate, the Coriolis forces Fx, Fy, Fz due to the angular velocity are not detected. Since there is a relationship of f = m · α based on the mass m of the vibrator 130 between the force f caused by acceleration and the acceleration α, each axis is based on the obtained forces fx, fy, and fz. Directional accelerations αx, αy, αz can be detected.

  Subsequently, in step S12, the detection value Fy of the Y-axis direction force detection unit 152 is obtained in a state where the vibration Uz is applied to the vibrator 130 (that is, the state where the Z-axis direction excitation unit 143 is driven). Then, the angular velocity ωx about the X axis is detected based on the formula Fy = 2m · vz · ωx. Here, m is the mass of the vibrator 130, and vz is the instantaneous velocity of the vibrator 130 in the Z-axis direction. This detection method is based on the principle shown in FIG. The instantaneous speed vz can be estimated from the operating state of the Z-axis direction excitation means 143. For example, in the specific configuration example shown in §2 described above, the Z-axis direction excitation unit 143 is driven by supplying a predetermined AC voltage to the upper electrodes E1 to E4. It is possible to estimate the instantaneous velocity vz from the frequency and the phase at the instantaneous instant.

  In the next step S13, the detection value Fz of the Z-axis direction force detection means 153 is obtained in a state where the vibration Ux is applied to the vibrator 130 (that is, a state where the X-axis direction excitation means 141 is driven). Then, the angular velocity ωy about the Y axis is detected based on the formula Fz = 2m · vx · ωy. Here, vx is the instantaneous velocity of the vibrator 130 in the X-axis direction, and can be estimated from the operating state of the X-axis direction excitation unit 141. This detection method is based on the principle shown in FIG.

  Subsequently, in step S14, the detection value Fx of the X-axis direction force detection unit 151 is obtained in a state where the vibration Uy is applied to the vibrator 130 (that is, a state where the Y-axis direction excitation unit 142 is driven). Then, the angular velocity ωz about the Z axis is detected based on the formula Fx = 2m · vy · ωz. Here, vy is the instantaneous velocity of the vibrator 130 in the Y-axis direction, and can be estimated from the operating state of the Y-axis direction excitation means 142. This detection method is based on the principle shown in FIG.

  Finally, as long as the detection operation is continued through step S15, the processing from step S11 is repeatedly executed. As described above, the step of detecting the accelerations αx, αy, αz in the respective axial directions without vibrating the vibrator 130 (step S11), and the respective speeds around the respective axes while vibrating the vibrator 130 in a predetermined direction. By separately performing the steps (steps S12 to S14) of detecting ωx, ωy, and ωz, both acceleration and angular velocity are obtained. In an environment in which acceleration and angular velocity are constantly acting, forces fx, fy, and fz resulting from acceleration are detected by being mixed with Coriolis forces Fx, Fy, and Fz in the angular velocity detection process in steps S12 to S14. Therefore, it is necessary to perform subtraction using the values of fx, fy, and fz detected in step S11 to extract only the components of the Coriolis forces Fx, Fy, and Fz.

  Now, the problem of this “basic detection operation” is that the responsiveness deteriorates when it is used for applications in which the values of acceleration and angular velocity are continuously measured. In automobiles and industrial machines, it is often required to continuously obtain acceleration and angular velocity values that change from moment to moment at regular intervals. However, when performing the detection operation based on the flowchart shown in FIG. 20, the vibrator that has been stationary in step S11 is vibrated in the Z-axis direction in step S12, vibrated in the X-axis direction in step S13, and Y in step S14. It is necessary to vibrate in the axial direction and stop again in step S11. It is very difficult to change such a mechanical vibration condition for the vibrator at high speed. In practice, in order to proceed to the next step in the detection operation of FIG. It takes a certain amount of time to get For this reason, the responsiveness is inevitably deteriorated.

<<< §4. Separation of force caused by acceleration and force caused by angular velocity >>>
The feature of the detection operation according to the present invention is that the detection of acceleration and the detection of angular velocity are performed simultaneously. For this purpose, it is necessary to separate the forces detected by the force detection means 151, 152, and 153 into a force caused by acceleration and a Coriolis force caused by angular velocity. Here, this separation method will be described with reference to a specific example.

  Here, a specific example taking the model shown in FIG. 3 as an example will be described. FIG. 3 is a diagram for explaining the detection principle of the angular velocity ωx about the X axis. That is, if the Coriolis force Fy generated in the Y-axis direction is detected in a state where the vibration Uz in the Z-axis direction is applied to the vibrator 130, the angular velocity around the X-axis is obtained from the relational expression Fy = 2m · vz · ωx. ωx is obtained. Thus, a case is considered where an angular velocity ωx around the X axis as shown in FIG. 21B is applied to the vibrator 130 in a state where the vibration Uz in the Z-axis direction as shown in FIG. . In either case, the horizontal axis is time t. The vibration Uz indicates a change in the physical position of the vibrator 130, and in this example, a sine motion is performed up and down. Further, the angular velocity ωx acting in this case is an angular velocity around the positive direction of the X axis (for example, clockwise), and gradually increases and decreases gradually with time. At this time, the Coriolis force Fy generated in the Y-axis direction is obtained by the relational expression Fy = 2m · vz · ωx. Here, the instantaneous velocity vz of the vibrator 130 in the Z-axis direction is expressed by the phase of the vibration Uz (π / 2) It will be shifted. This is because the instantaneous velocity of an object that is sine-moving up and down is maximized at the moment of passing through the center position, and is 0 at the highest point and the lowest point (here, FIG. 21 (a)). In the vibration shown in FIG. 4, the speed in the downward direction is positive and the speed in the upward direction is negative). Since the mass m of the vibrator 130 is constant, the Coriolis force Fy is determined by the product of the instantaneous velocity vz and the angular velocity ωx, and is as shown in FIG. After all, in the model of FIG. 3, when the angular velocity ωx as shown in FIG. 21 (b) is applied to the vibrator 130 with the vibration Uz as shown in FIG. 21 (a), FIG. A Coriolis force Fy as shown in (c) is generated.

  On the other hand, what kind of force is generated in the Y-axis direction when acceleration in the Y-axis direction acts on the vibrator 130? Since the force fy in the Y-axis direction generated by the acceleration αy in the Y-axis direction is given by the relational expression fy = m · αy, a force fy proportional to the given acceleration αy is generated. Therefore, assuming that an acceleration αy linearly increasing is given to the vibrator 130, a force fy in the Y-axis direction as shown in FIG. 21 (d) is generated.

  Then, in the model of FIG. 3, the angular velocity ωx around the X axis as shown in FIG. 21 (b) is obtained when the vibrator 130 is given a vibration Uz in the Z-axis direction as shown in FIG. 21 (a). What force is observed in the Y-axis direction when the acceleration αy in the Y-axis direction acting and increasing linearly acts? In this case, naturally, a combined force corresponding to the sum of the Coriolis force Fy as shown in FIG. 21C and the force fy based on the acceleration as shown in FIG. 21D is observed. FIG. 22 shows such a combined force fy + Fy.

  If the resultant force fy + Fy can be separated into the force fy and the Coriolis force Fy, the former can determine the acceleration αy in the Y-axis direction, and the latter can determine the angular velocity ωx around the X-axis. be able to. That is, simultaneous detection of acceleration and angular velocity is possible. The present inventor has found that this separation can be performed by paying attention to the following points. That is, if only the bias component is extracted from the combined force fy + Fy shown in FIG. 22, only the force fy shown in FIG. 21 (d) can be extracted, and if only the amplitude component is extracted, FIG. 21 (c) is obtained. Only the Coriolis force Fy shown can be taken out. In the first place, the Coriolis force Fy shown in FIG. 21 (c) is obtained by amplitude-modulating the angular velocity ωx shown in FIG. 21 (b) using the vibration Uz shown in FIG. 21 (a) as a carrier wave. Therefore, the information on the angular velocity ωx is included only as an amplitude component in the combined force. On the other hand, since the force fy shown in FIG. 21 (d) does not include the frequency component of the vibration Uz, the information is included only as a bias component in the combined force. From this point of view, it can be understood that the force fy can be extracted if only the bias component is extracted from the combined force fy + Fy, and the Coriolis force Fy can be extracted if only the amplitude component is extracted.

  In order to separate the force f based on acceleration and the Coriolis force F based on angular velocity based on such a principle, the frequency of the vibration U is distinguished from the frequency of the acceleration or angular velocity to be detected. It must be as high as possible. In other words, the detection device according to the present invention can detect only a frequency component that is sufficiently lower than the frequency of the vibration U among the acceleration and angular velocity to be detected. However, such a restriction is not a problem for practical use as a detection device mounted on an automobile or an industrial machine. Specifically, when vibrating a vibrator using a piezoelectric element as described in §2, it is most efficient to vibrate at a resonance frequency of about 20 kHz. In this case, it is sufficiently possible to detect acceleration and angular velocity having frequency components of several hundred Hz or less, and such performance is required for detection devices mounted on general automobiles and industrial machines. Is fully satisfied.

  As a method for separating the combined force into a bias component and an amplitude component based on the principle as described above, for example, a method using a frequency filter can be used. However, in recent years, with the widespread use of computers, it has become common to perform A / D conversion on the obtained electrical signals and perform digital processing. The inventor of the present application has found the following separation method using such digital processing.

  First, as shown in FIG. 23, inflection points P1 to P9 are extracted from the detection signal of the combined force fy + Fy as shown in FIG. Then, as shown in FIG. 24, lane markings Q1 to Q9 indicating the positions of the inflection points P1 to P9 on the time axis t are defined, and reference lines Q12 to Q89 passing through intermediate positions of adjacent lane markings (FIG. 24). In FIG. 24, a broken line) is defined. Then, on each reference line, a reference point m having an average value of the signal values at the inflection points on both sides is plotted. FIG. 25 shows the reference points m1 to m8 plotted in this way. For example, the reference point m1 is a point on the reference line Q12 having an average value of the signal value at the inflection point P1 and the signal value at the inflection point P2. Thus, when the reference points m1 to m8 are obtained, a signal waveform obtained by connecting these in order is obtained as shown in FIG. The signal waveform thus obtained corresponds to the bias component of the original combined force fy + Fy, and eventually corresponds to the force fy based on the acceleration αy. Once the bias component is obtained, a signal waveform corresponding to the amplitude component can be obtained by subtracting this from the original combined force, and eventually a signal waveform corresponding to the Coriolis force Fy can be obtained. Note that the magnitude of the angular velocity ωx is obtained by extracting an envelope E of a signal waveform corresponding to the Coriolis force Fy, as shown in FIG. Further, the direction of the angular velocity ωx can be obtained by the phase difference between the obtained Coriolis force Fy and the vibration Uz shown in FIG. For example, when a positive angular velocity ωx as shown in FIG. 21B is added, the waveform of the Coriolis force Fy obtained with respect to the waveform of the vibration Uz shown in FIG. As shown in (c), the phase is shifted to the right by (π / 2), but when the negative angular velocity −ωx is added, the vibration shown in FIG. 21 (a) is the same. A Coriolis force waveform obtained by inverting the sign of FIG. 21C with respect to the waveform of Uz is obtained. This Coriolis force waveform shifts the phase of the waveform of the vibration Uz to the left by (π / 2). Become a thing.

<<< §5. First Embodiment of Detection Device According to the Present Invention >>
The detection apparatus according to the present invention separates the resultant force into force f (bias component) based on acceleration and Coriolis force F (amplitude component) based on angular velocity based on the basic principle described in §4 above. By using means, acceleration and angular velocity can be detected simultaneously. FIG. 28 is a block diagram showing the basic configuration of the detection apparatus according to the first embodiment of the present invention. In this detection apparatus, an X-axis direction signal separation means 161, a Y-axis direction signal separation means 162, and a Z-axis direction signal separation means 163 are added to each component of the detection apparatus shown in FIG. 171 to 173 and angular velocity calculation means 181 to 183 are added.

  Each of the signal separation means 161 to 163 is based on the basic principle described in §4, and the combined forces fx + Fx, fy + Fy, fz + Fz obtained from the force detection means 151 to 153 are converted into fx, Fx, fy and Fy, respectively. , Fz and Fz. Further, each acceleration calculation means 171 to 173 uses the mass m of the vibrator 130 to calculate and output accelerations αx, αy, αz in the respective axial directions based on the relational expression f = m · α. It is. Since the acceleration acting on the vibrator 130 is detected as a force f regardless of the vibration of the vibrator 130, each acceleration calculation means 171 to 173 is independent of the operation of each excitation means 141 to 143. Directional accelerations αx, αy, αz are output.

  On the other hand, each angular velocity calculation means 181 to 183 is a device that calculates and outputs angular velocities ωx, ωy, and ωz around each axis based on the principle shown in FIGS. However, the detection of the angular velocities ωx, ωy, and ωz is closely related to the vibration of the vibrator 130 as shown in the principle diagrams of FIGS. In other words, each of the angular velocity calculation means 181 to 183 cannot calculate the angular velocity unless the operating state of each of the excitation means 141 to 143 is taken into consideration. This will be explained for each individual case.

  First, based on the principle shown in FIG. 3, in order to detect the angular velocity ωx around the X axis, in the state where the Z axis direction excitation means 143 is driven and the oscillator 130 is given a vibration Uz in the Z axis direction, The Coriolis force Fy in the Y-axis direction separated by the axial direction signal separation unit 162 is given to the angular velocity calculation unit 182. The angular velocity calculation means 182 calculates an angular velocity ωx around the X axis based on an arithmetic expression of Fy = 2 m · vz · ωx, and outputs this. At this time, the instantaneous velocity vz of the vibrator 130 in the Z-axis direction is estimated based on the operation mode of the Z-axis direction excitation unit 143. For example, in the detection device having the specific structure described in §2, a predetermined alternating voltage is supplied to the upper electrodes E1 to E4 to give the vibration Uz. It can be determined based on the amplitude, frequency, and phase of the AC voltage supplied at the point in time (the relationship between the AC voltage to be supplied and the instantaneous speed of the vibrator can be obtained or supplied by a theoretical arithmetic expression) It is also possible to prepare a table that measures the instantaneous speed of the vibrator for one period of AC voltage). Note that “FIG. 3: ωx (Uz)” is written in the output of the angular velocity calculating means 182 in FIG. 28 because “under the condition that the vibration Uz is given to the vibrator 130 based on the principle shown in FIG. The angular velocity ωx is output ”.

  Next, in order to detect the angular velocity ωy about the Y-axis based on the principle shown in FIG. 4, in the state where the X-axis direction excitation unit 141 is driven and the vibrator 130 is given the vibration Ux in the X-axis direction, The Coriolis force Fz in the Z-axis direction separated by the Z-axis direction signal separation unit 163 is applied to the angular velocity calculation unit 183. The angular velocity calculation means 183 calculates an angular velocity ωy about the Y axis based on an arithmetic expression of Fz = 2m · vx · ωy, and outputs this. At this time, the instantaneous velocity vx of the vibrator 130 in the X-axis direction is estimated based on the operation mode of the X-axis direction excitation unit 141. Note that “FIG. 4: ωy (Ux)” is written in the output of the angular velocity calculating means 183 in FIG. 28 because “under the condition that the vibration Ux is given to the vibrator 130 based on the principle shown in FIG. The angular velocity ωy is output ”.

  Further, in order to detect the angular velocity ωz about the Z-axis based on the principle shown in FIG. 5, in the state where the Y-axis direction excitation means 142 is driven and the vibrator 130 is given the vibration Uy in the Y-axis direction, The Coriolis force Fx in the X-axis direction separated by the axial direction signal separation unit 161 is given to the angular velocity calculation unit 181. The angular velocity calculation means 181 calculates an angular velocity ωz around the Z axis based on an arithmetic expression of Fx = 2m · vy · ωz, and outputs this. At this time, the instantaneous velocity vy of the vibrator 130 in the Y-axis direction is estimated based on the operation mode of the Y-axis direction excitation unit 142. Note that “FIG. 5: ωz (Uy)” is written in the output of the angular velocity calculating means 181 in FIG. 28 because “under the condition that the vibration Uy is given to the vibrator 130 based on the principle shown in FIG. The angular velocity ωz is output ”.

  Thus, according to the detection apparatus shown in FIG. 28, the acceleration αx in the X-axis direction from the acceleration calculator 171, the acceleration αy in the Y-axis direction from the acceleration calculator 172, and the Z-axis direction from the acceleration calculator 173 in the end. , And the angular velocity ωx around the X axis from the angular velocity computing means 182, the angular velocity ωy around the Y axis from the angular velocity computing means 183, and the angular velocity ωy around the Z axis from the angular velocity computing means 181. Each angular velocity ωz is output. Note that the angular velocity calculation means 181 to 183 shown in FIG. 28 also obtain outputs of “FIG. 31: ωy (Uz)”, “FIG. 32: ωz (Ux)”, and “FIG. 30: ωx (Uy)”. This will be explained in §6.

  With the detection device shown in FIG. 28, the detection operation for detecting the accelerations αx, αy, αz in the respective axis directions and the angular velocities ωx, ωy, ωz around the respective axes is described as “detection according to the first embodiment. The operation "is shown in the flowchart of FIG.

  First, in step S21, in a state where the vibration Uz is applied to the vibrator 130 (that is, a state where the Z-axis direction excitation unit 143 is driven), the combined force fy + Fy is extracted from the Y-axis direction force detection unit 152, and the Y-axis direction signal is obtained. Separation means 162 separates force fy and Coriolis force Fy. Then, the acceleration calculating means 172 calculates the acceleration αy based on the force fy and outputs it, and the angular velocity calculating means 182 calculates the angular velocity ωx based on the Coriolis force Fy and outputs this. Thus, in step S21, the acceleration αy and the angular velocity ωx can be detected.

  Next, in step S22, in a state where the vibration Ux is applied to the vibrator 130 (that is, a state where the X-axis direction excitation unit 141 is driven), the resultant force fz + Fz is taken out from the Z-axis direction force detection unit 153, and the Z-axis direction The signal separation means 163 separates the force fz and the Coriolis force Fz. The acceleration calculating means 173 calculates the acceleration αz based on the force fz and outputs it, and the angular velocity calculating means 183 calculates the angular velocity ωy based on the Coriolis force Fz and outputs it. Thus, in step S21, the acceleration αz and the angular velocity ωy can be detected.

  Subsequently, in step S23, in a state where the vibration Uy is applied to the vibrator 130 (that is, a state where the Y-axis direction excitation unit 142 is driven), the resultant force fx + Fx is taken out from the X-axis direction force detection unit 151, and an X-axis direction signal is obtained. Separation means 161 separates force fx and Coriolis force Fx. The acceleration calculating means 171 calculates the acceleration αx based on the force fx and outputs it, and the angular velocity calculating means 181 calculates the angular velocity ωz based on the Coriolis force Fx and outputs it. Thus, in step S21, the acceleration αx and the angular velocity ωz can be detected.

  Finally, as long as the detection operation is continued through step S24, the processing from step S21 is repeatedly executed. In the “detection operation according to the first embodiment” shown in FIG. 29, one step is omitted compared to the “basic detection operation” shown in FIG. That is, in the “basic detection operation”, in order to perform acceleration detection, detection was performed while the vibrator was kept stationary in step S11, whereas “according to the first embodiment” described here. In the “detection operation”, since the acceleration can be detected even when the vibrator is vibrated, it is not necessary to stop the vibrator. For this reason, in the detection apparatus shown in FIG. 28, the responsiveness is improved as compared with the conventionally proposed detection apparatus.

<<< §6. Second Embodiment of Detection Device According to the Present Invention >>
In §5, the detection apparatus having the basic configuration shown in FIG. 28 and its operation are described. According to the operation, regarding the angular velocity, the angular velocity ωx around the X axis is output from the angular velocity calculating means 182 based on the principle of FIG. 3, and the angular velocity ωy around the Y axis is output based on the principle of FIG. The angular velocity ωz around the Z axis is outputted from the angular velocity calculating means 181 based on the principle of FIG. However, in FIG. 28, regarding the outputs of the respective angular velocity calculation means 181 to 183, there are different “FIG. 30: ωy (Uz)”, “FIG. 31: ωz (Ux)”, and “FIG. 29: ωx (Uy)”. There is a description that output is also obtained. This indicates that there are combinations of FIGS. 30 to 32 in addition to the combinations of FIGS. 3 to 5 as the detection principle of each angular velocity. That is, the detection of the angular velocity using the Coriolis force is as follows: “When the Coriolis force generated in the second coordinate axis direction is detected when vibration is applied in the first coordinate axis direction, the angular velocity around the third coordinate axis is obtained. The first, second, and third coordinate axes in this basic principle are changed to the X-axis, Y-axis, and Z-axis coordinate axes in the XYZ three-dimensional coordinate system. It does not matter if it is supported.

  Even if the angular velocity ωx around the same X axis is detected, in FIG. 3, the Coriolis force Fy generated in the Y axis direction when the vibration Uz in the Z axis direction is applied is detected. In 30, the Coriolis force Fz generated in the Z-axis direction when the vibration Uy in the Y-axis direction is applied is detected. Further, even in the method of detecting the angular velocity ωy around the same Y axis, in FIG. 4, the Coriolis force Fz generated in the Z axis direction when the vibration Ux in the X axis direction is applied is detected. In FIG. 31, the Coriolis force Fx generated in the X-axis direction when the vibration Uz in the Z-axis direction is applied is detected. Similarly, even in the method of detecting the angular velocity ωz around the same Z axis, FIG. 5 detects the Coriolis force Fx generated in the X axis direction when the vibration Uy in the Y axis direction is applied. On the other hand, in FIG. 32, the Coriolis force Fy generated in the Y-axis direction when the vibration Ux in the X-axis direction is applied is detected.

  Therefore, the detection apparatus shown in FIG. 28 can be operated based on the principle shown in FIGS. This will be explained for each individual case.

  First, based on the principle shown in FIG. 30, in order to detect the angular velocity ωx around the X-axis, in the state where the Y-axis direction excitation means 142 is driven and the vibrator 130 is given the vibration Uy in the Y-axis direction, The Coriolis force Fz in the Z-axis direction separated by the axial direction signal separation means 163 is given to the angular velocity calculation means 183. The angular velocity calculation means 183 calculates an angular velocity ωx around the X axis based on an arithmetic expression of Fz = 2m · vy · ωx, and outputs this. At this time, the instantaneous velocity vy of the vibrator 130 in the Y-axis direction is estimated based on the operation mode of the Y-axis direction excitation unit 142. “FIG. 30: ωx (Uy)” is written in the output of the angular velocity calculation means 183 because “the angular velocity ωx is output under the condition that the vibration Uy is applied to the vibrator 130 based on the principle shown in FIG. It is shown that.

  Next, in order to detect the angular velocity ωy about the Y-axis based on the principle shown in FIG. 31, in the state where the Z-axis direction excitation means 143 is driven to give the vibrator 130 the vibration Uz in the Z-axis direction. The Coriolis force Fx in the X-axis direction separated by the X-axis direction signal separating unit 161 is applied to the angular velocity calculating unit 181. The angular velocity calculation means 181 calculates an angular velocity ωy about the Y axis based on an arithmetic expression of Fx = 2m · vz · ωy, and outputs this. At this time, the instantaneous velocity vz of the vibrator 130 in the Z-axis direction is estimated based on the operation mode of the Z-axis direction excitation unit 143. “FIG. 31: ωy (Uz)” is written in the output of the angular velocity calculation means 181 because “the angular velocity ωy is output under the condition that the vibration Uz is given to the vibrator 130 based on the principle shown in FIG. It is shown that.

  Further, in order to detect the angular velocity ωz about the Z-axis based on the principle shown in FIG. 32, in the state where the X-axis direction excitation means 141 is driven and the vibrator 130 is given the vibration Ux in the X-axis direction, The Coriolis force Fy in the Y-axis direction separated by the axial direction signal separation unit 162 is given to the angular velocity calculation unit 182. The angular velocity calculation means 182 calculates an angular velocity ωz around the Z axis based on an arithmetic expression of Fy = 2m · vx · ωz, and outputs this. At this time, the instantaneous velocity vx of the vibrator 130 in the X-axis direction is estimated based on the operation mode of the X-axis direction excitation unit 141. The reason why “FIG. 32: ωz (Ux)” is written in the output of the angular velocity calculation means 182 is that “the angular velocity ωz is output under the condition that the vibration Ux is applied to the vibrator 130 based on the principle shown in FIG. It is shown that.

  As described above, the detection apparatus shown in FIG. 28 is applied with any of the detection method based on the three principles shown in FIGS. 3 to 5 and the detection method based on the three principles shown in FIGS. However, the inventor of the present application has realized that the detection operation and the device configuration can be further simplified by selecting three principles out of the total of six principles. The second embodiment described here is a further simplification of the first embodiment described in Section 5 based on such a basic idea.

  Now, in the apparatus according to the first embodiment shown in FIG. 28, the following three principles are selected as the angular velocity detection principle: ωx detection according to FIG. 3, ωy detection according to FIG. 31, and ωz detection according to FIG. Suppose that Then, the detection apparatus according to the first embodiment shown in FIG. 28 is simplified to the detection apparatus according to the second embodiment as shown in FIG. The detection apparatus of FIG. 33 is obtained by deleting the Y-axis direction excitation means 142 and the angular velocity calculation means 183 from the detection apparatus of FIG. As long as the selected three detection principles shown in FIGS. 3, 31, and 32 are adopted, it is not necessary to apply the vibration Uy in the Y-axis direction, and the angular velocity calculation using the Coriolis force Fz in the Z-axis direction is not necessary. is there.

  The detection operation shown in FIG. 33 for detecting the accelerations αx, αy, αz in the directions of the respective axes and the angular velocities ωx, ωy, ωz around the respective axes is “detection by the second embodiment”. As an operation | movement, it shows in the flowchart of FIG.

  First, in step S31, the following two types of detection are performed in a state where the vibration Uz is applied to the vibrator 130 (that is, the state where the Z-axis direction excitation unit 143 is driven). As the first detection, the combined force fy + Fy is taken out from the Y-axis direction force detecting means 152 and separated into the force fy and the Coriolis force Fy by the Y-axis direction signal separating means 162. Then, the acceleration calculating means 172 calculates the acceleration αy based on the force fy and outputs it, and the angular velocity calculating means 182 calculates the angular velocity ωx based on the Coriolis force Fy and outputs this. This is detection based on the principle of FIG. At the same time, the following second detection is performed. That is, the combined force fx + Fx is taken out from the X-axis direction force detecting means 151 and separated into the force fx and the Coriolis force Fx by the X-axis direction signal separating means 161. Then, the acceleration calculating means 171 calculates the acceleration αx based on the force fx and outputs it, and the angular velocity calculating means 181 calculates the angular velocity ωy based on the Coriolis force Fx and outputs this. This is detection based on the principle of FIG. Thus, in step S31, the accelerations αy, αy and the angular velocities ωx, ωy can be detected.

  Next, in step S32, the following two types of detection are performed in a state where the vibration Ux is applied to the vibrator 130 (that is, a state where the X-axis direction excitation unit 141 is driven). As the first detection, the combined force fz + Fz is taken out from the Z-axis direction force detection means 153 and separated into the force fz and the Coriolis force Fz by the Z-axis direction signal separation means 163. Then, the acceleration calculation means 173 calculates the acceleration αz based on the force fz and outputs it. In this first detection, it is only necessary to detect the acceleration (if the principle of FIG. 4 is used, the angular velocity ωy can be obtained based on the Coriolis force Fz, but the angular velocity ωy has already been obtained in step S31. It has been demanded). At the same time, the following second detection is performed. That is, the combined force fy + Fy is taken out from the Y-axis direction force detection unit 152 and separated into the force fy and the Coriolis force Fy by the Y-axis direction signal separation unit 162. Then, the angular velocity calculation means 182 calculates the angular velocity ωz based on the Coriolis force Fy and outputs it. This is detection based on the principle of FIG. Thus, in step S32, the acceleration αz and the angular velocity ωz can be detected.

  Finally, as long as the detection operation is continued through step S33, the processing from step S31 is repeatedly executed. The “detection operation according to the second embodiment” shown in FIG. 34 further omits one step compared to the “detection operation according to the first embodiment” shown in FIG. That is, in the “detection operation according to the first embodiment”, detection is performed in a state where the vibrator is vibrated in the three axial directions of the X axis, the Y axis, and the Z axis, whereas “ In the “detection operation according to the second embodiment”, all the detections can be performed only in the state of vibrating in the two-axis directions of the X axis and the Z axis. For this reason, in the detection apparatus shown in FIG. 33, the responsiveness is further improved.

<<< §7. Third Embodiment of Detection Device According to the Present Invention >>
Up to now, three-dimensional acceleration / angular velocity detection that detects six components of the accelerations αx, αy, αz in the X-axis, Y-axis, and Z-axis directions and the angular velocities ωx, ωy, ωz around each axis. An example of an apparatus has been described. However, depending on the application, the demand for a two-dimensional acceleration / angular velocity detection device that only needs to obtain the accelerations αx and αy in the biaxial directions of the X axis and the Y axis and the angular velocities ωx and ωy around the two axes is sufficiently considered. It is done. The configuration of the third embodiment in which the present invention is applied to such a two-dimensional detection apparatus is further simplified.

  FIG. 35 is a block diagram showing the basic configuration of the third embodiment. Compared with the second embodiment shown in FIG. 33, the X-axis direction excitation means 141, the Z-axis direction force detection means 153, and the acceleration calculation means 173 are further deleted. Even with such a configuration, the necessary acceleration and angular velocity can be detected without any problem. That is, the acceleration αx is obtained by the acceleration computing means 171 and the acceleration αy is obtained by the acceleration computing means 172. Further, the angular velocity ωx is obtained by the angular velocity calculation means 182 in the state where the vibration Uz is given by the Z-axis direction excitation means 143 (the principle of FIG. 3), and the angular velocity ωy gives the vibration Uz by the Z-axis direction excitation means 143. In this state, it is obtained by the angular velocity calculation means 181 (the principle of FIG. 31).

  35, the detection operation for detecting the biaxial accelerations αx, αy and the angular velocities ωx, ωy about the biaxial directions is performed according to the “second embodiment” shown in FIG. Only step S31 in the “detection operation” is sufficient. In other words, the “detection operation according to the third embodiment” is an operation including only step S31 in FIG. This means that if the vibrator 130 is always vibrated only in the Z-axis direction, all detection values can be obtained. As described above, since it is not necessary to change the vibration mode of the vibrator, a very efficient detection operation is possible, and the response is extremely good.

<<< §8. Specific detection device structure suitable for two-dimensional detection >>>
As described in §7 above, in a two-dimensional detection device for the purpose of obtaining only the accelerations αx and αy in the biaxial directions of the X axis and the Y axis and the angular velocities ωx and ωy around the two axes, As shown in the block diagram of FIG. 35, only the Z-axis direction excitation means 143 may be provided as the excitation means, and the X-axis direction force detection means 151 and the Y-axis direction force detection are provided as the force detection means. Only the means 152 need be provided. Therefore, in such a two-dimensional detection device, the number of upper electrodes provided on the piezoelectric element can be reduced as compared with a three-dimensional detection device. For example, in the three-dimensional detection apparatus shown in FIG. 10, on the piezoelectric element 10, four upper electrodes E1 to E4 that function as excitation means, and eight upper electrodes A1 to A8 that function as force detection means, To realize excitation and force detection in all three axis directions. However, a two-dimensional detection device can be realized with a structure having fewer upper electrodes.

  FIG. 36 is a top view showing a specific example of the structure of a detection device suitable for two-dimensional detection, and FIG. 37 is a side sectional view of the detection device taken along the XZ plane. The correspondence between each upper electrode in this detection apparatus and the block elements shown in FIG. 35 is as follows. First, the upper electrode E10 functions as the Z-axis direction excitation unit 143, and by applying a predetermined AC voltage between the upper electrode E10 and the lower electrode B, the center part 11 can be vibrated in the Z-axis direction. it can. Further, the upper electrodes A11 and A12 function as the X-axis direction force detecting means 151, and can detect the displacement of the central portion 11 in the X-axis direction based on the electric charges generated here. Further, the upper electrodes A13 and A14 function as the Y-axis direction force detecting means 152, and can detect the displacement of the central portion 11 in the Y-axis direction based on the electric charges generated here. Eventually, the two-dimensional detection device shown in FIG. 35 can be realized only by providing the five upper electrodes E10, A11 to A14 on the piezoelectric element 10.

  FIG. 38 is a top view showing still another structural example of a specific detection apparatus suitable for two-dimensional detection, and FIG. 39 is a side sectional view of the detection apparatus cut along the XZ plane. The only difference between the detection device shown in FIG. 38 and the detection device shown in FIG. 36 is that the positional relationship between the upper electrode for excitation and the upper electrode for force detection is reversed. The correspondence between each upper electrode in this detection apparatus and the block elements shown in FIG. 35 is as follows. First, the upper electrode E20 functions as the Z-axis direction excitation means 143, and by applying a predetermined AC voltage between the upper electrode E20 and the lower electrode B, the center part 11 can be vibrated in the Z-axis direction. it can. Further, the upper electrodes A21 and A22 function as the X-axis direction force detecting means 151, and can detect the displacement of the central portion 11 in the X-axis direction based on the electric charges generated here. Further, the upper electrodes A23 and A24 function as the Y-axis direction force detecting means 152, and can detect the displacement of the central portion 11 in the Y-axis direction based on the electric charges generated here.

  In this way, in a detection device that requires only two-dimensional detection, the overall manufacturing cost can be reduced by configuring the upper electrode with a minimum number.

<<< §9. Capacitive detection device to which the present invention is applied >>
As an example of a detection apparatus to which the present invention is applied, in §2, an apparatus using the piezoelectric element 10 has been described. As described above, the present invention can be applied to any detection device having the configuration shown in the block diagram of FIG. 6, but here, for reference. An example of a capacitive detection device to which the present invention is applied will be briefly described. This detection apparatus is disclosed in Patent Document 1 described above.

  FIG. 40 is a side sectional view of this capacitive detection device 200. The main components of this detection apparatus are a strain generating body 210, a vibrator 220, a pedestal 230, a base substrate 240, and a lid plate 250. A top view of the strain body 210 is shown in FIG. As shown in FIG. 41, the strain body 210 is a square metal plate, and an annular groove as shown by a broken line in FIG. 41 is formed on the lower surface thereof. As clearly shown in the side sectional view of FIG. 40, the thickness of the strain generating body 210 is reduced in the groove forming portion, and this portion has a flexible structure. Here, the strain generating body 210 is placed outside the center groove 211 that exists inside the annular groove, the thin flexible section 212 that exists above the annular groove, and outside the annular groove. The three surrounding parts 213 and the existing surrounding part 213 will be considered. The vibrator 220 is bonded to the bottom surface of the central portion 211. The vibrator 220 is a disk-shaped metal block having a certain amount of mass, and acceleration and angular velocity are detected by a force based on the acceleration acting on the vibrator 220 and a Coriolis force. On the other hand, a pedestal 230 is bonded to the bottom surface of the peripheral portion 213 so as to surround the vibrator 220, and the bottom surface of the pedestal 230 is bonded to the base substrate 240. Eventually, the vibrator 220 is suspended in a space surrounded by the pedestal 230. Further, a lid plate 250 is joined to the upper surface of the strain generating body 210, and this lid plate 250 has a structure capable of securing a space as shown in the figure.

  In the space formed between the upper surface of the strain body 210 and the lower surface of the cover plate 250, the upper electrode E0 and the lower electrodes F1 to F5 are disposed. The lower electrodes F <b> 1 to F <b> 5 are electrodes having a shape as shown in FIG. 41, and are fixed to positions as illustrated on the upper surface of the strain generating body 210. On the other hand, the upper electrode E0 is a disk-like electrode that can function as a common electrode facing all of the five lower electrodes F1 to F5, and is fixed to the lower surface of the lid plate 250. Eventually, five sets of capacitive elements are formed by the individual lower electrodes F1 to F5 and the common upper electrode E0.

  As described above, the vibrator 220 is suspended in the space surrounded by the pedestal 230, and the flexible portion 212 has flexibility. Therefore, the vibrator 220 has three axial directions of XYZ shown in the drawing. Can move with a certain degree of freedom. Therefore, if a predetermined AC voltage is applied between the electrodes, the vibrator 220 can be vibrated in a desired direction. For example, if charges having the same polarity are applied between the lower electrode F1 and the upper electrode E0, a repulsive force due to Coulomb force acts, and the distance between both electrodes is increased. At the same time, if charges having different polarities are applied between the lower electrode F2 and the upper electrode E0, an attractive force due to Coulomb force acts, and the distance between both electrodes is reduced. As a result, the vibrator 220 is displaced in the positive direction of the X axis. If the relationship between the repulsive force and the attractive force is reversed, the vibrator 220 is displaced in the negative direction of the X axis. Thus, if positive and negative displacements along the X axis are performed alternately, the vibrator 220 vibrates along the X axis. If the same thing is done using the lower electrodes F3 and F4, the vibrator 220 can be vibrated along the Y axis. Furthermore, if the lower electrode F5 is used, vibration along the Z-axis direction is also possible. That is, if the same polarity charge is applied to the lower electrode F5 and the upper electrode E0, the distance between the two electrodes is widened by the repulsive action, and if the charge of different polarity is given, the distance between the two electrodes is narrowed by the attractive action. Thus, the vibrator 220 vibrates along the Z-axis direction. Thus, this apparatus includes the excitation means 141 to 143 in the respective axial directions shown in FIG.

  On the other hand, this apparatus is also an apparatus provided with force detecting means 151 to 153 in the respective axial directions shown in FIG. Consider a case where a force based on acceleration or a Coriolis force is applied to the vibrator 220. For example, when a force in the X-axis direction is applied, the vibrator 220 is displaced in the X-axis, so the distance between the lower electrode F1 and the upper electrode E0 and the distance between the lower electrode F2 and the upper electrode E0, Each will change. Further, when a force in the Y-axis direction is applied, the vibrator 220 is displaced in the Y-axis direction, so that the distance between the lower electrode F3 and the upper electrode E0 and the distance between the lower electrode F4 and the upper electrode E0. , Each will change. Further, when a force in the Z-axis direction is applied, the vibrator 220 is displaced in the Z-axis direction, so that the distance between the lower electrode F5 and the upper electrode E0 is changed. Such a change in the distance between the pair of opposing electrodes affects the capacitance value of the capacitive element formed by the pair of electrodes. Therefore, if the change in the capacitance value of each capacitive element can be detected electrically, the displacement of the vibrator 220 can be detected, and as a result, each axial direction acting on the vibrator 220 can be detected. Force can be detected.

  As described above, the capacitive detection device 200 includes the excitation means 141 to 143 in the axial directions and the force detection means 151 to 153 in the axial directions shown in FIG. The present invention can be applied in the same manner as the piezoelectric detection device. In the illustrated capacitive detection device 200, each of the lower electrodes F1 to F5 functions as both an excitation unit and a force detection unit. Thus, it is preferable that the part functioning as the excitation means and the part functioning as the force detection means have a physically separated structure.

  Although the present invention has been described based on some embodiments shown in the drawings, the present invention is not limited to these embodiments and can be implemented in various other modes. In short, the basic idea of the present invention is that when the vibrator is vibrated, the resultant force acting on the vibrator is separated into a force f caused by acceleration and a Coriolis force F caused by angular velocity. As long as it is included in the category of such a technical idea, it may be implemented in any manner.

It is a perspective view which shows the basic principle of the one-dimensional angular velocity detection apparatus using the Coriolis force proposed conventionally. It is a figure which shows the angular velocity around each axis | shaft in the XYZ three-dimensional coordinate system used as the detection target in an angular velocity detection apparatus. It is a figure explaining the basic principle which detects angular velocity (omega) x around an X-axis using the detection apparatus which concerns on this invention. It is a figure explaining the basic principle which detects angular velocity (omega) y around the Y-axis using the detection apparatus which concerns on this invention. It is a figure explaining the basic principle which detects angular velocity (omega) z around Z-axis using the detection apparatus which concerns on this invention. It is a block diagram which shows the component which performs the angular velocity detection in the detection apparatus which concerns on this invention. It is a block diagram which shows the component which performs the acceleration detection in the detection apparatus which concerns on this invention. It is the perspective view which looked at the detection apparatus which concerns on the specific structural example of this invention from diagonally upward. It is the perspective view which looked at the detection apparatus shown in FIG. 8 from diagonally downward. It is a top view of the detection apparatus shown in FIG. It is the sectional side view which cut | disconnected the detection apparatus shown in FIG. 8 by XZ plane. It is a bottom view of the detection apparatus shown in FIG. It is a figure which shows the polarization characteristic of the piezoelectric element 10 in the detection apparatus shown in FIG. It is a sectional side view which shows the state which induced the displacement Dx of the X-axis direction with respect to the gravity center P of the detection apparatus shown in FIG. FIG. 9 is a side sectional view showing a state in which a displacement Dz in the Z-axis direction is induced with respect to the center of gravity P of the detection device shown in FIG. 8. FIG. 9 is a side cross-sectional view illustrating a state where a force fx in the X-axis direction is applied to the center of gravity P of the detection device illustrated in FIG. 8. FIG. 9 is a side sectional view showing a state in which a force fz in the Z-axis direction is applied to the center of gravity P of the detection device shown in FIG. 8. It is a table | surface which shows the polarity of the electric charge which generate | occur | produces in each upper electrode A1-A8 when force fx, fy, fz of each axial direction based on acceleration acts on the detection apparatus shown in FIG. It is a circuit diagram which shows an example of the detection circuit used for the detection apparatus shown in FIG. It is a flowchart which shows the procedure of the general detection operation | movement about the detection apparatus used as the application object of this invention. 6 is a graph showing specific conditions of vibration applied to a vibrator, applied angular velocity, generated Coriolis force, and applied acceleration in a detection apparatus to which the present invention is applied. It is a graph which shows the synthetic force actually detected on the conditions shown in FIG. It is a graph which shows the state which calculated | required inflection points P1-P9 about the graph of the synthetic force shown in FIG. It is a graph which shows the state which calculated | required reference lines Q12-Q89 based on the inflection points P1-P9 calculated | required in FIG. It is a graph which shows the state which plotted the reference points m1-m8 on the reference lines Q12-Q89 calculated | required in FIG. It is a graph which shows the state which extracted the force f which is a bias component of synthetic | combination force by connecting the reference points m1-m8 calculated | required in FIG. It is a graph which shows the state which calculates | requires angular velocity as the envelope E of Coriolis force Fy. It is a block diagram which shows the basic composition of the detection apparatus which concerns on 1st Example of this invention. It is a flowchart which shows the procedure of the detection operation | movement of the detection apparatus which concerns on 1st Example shown in FIG. It is a figure explaining another basic principle which detects angular velocity omegax around the X-axis using the detecting device concerning the present invention. It is a figure explaining another basic principle which detects angular velocity (omega) y around the Y-axis using the detection apparatus which concerns on this invention. It is a figure explaining another basic principle which detects angular velocity (omega) z around Z-axis using the detection apparatus which concerns on this invention. It is a block diagram which shows the basic composition of the detection apparatus which concerns on the 2nd Example of this invention. It is a flowchart which shows the procedure of the detection operation | movement of the detection apparatus which concerns on 2nd Example shown in FIG. It is a block diagram which shows the basic composition of the detection apparatus which concerns on the 3rd Example of this invention. It is a top view which shows the structure of the specific detection apparatus suitable for two-dimensional detection. It is the sectional side view which cut | disconnected the detection apparatus shown in FIG. 36 by XZ plane. It is a top view which shows the structure of another specific detection apparatus suitable for two-dimensional detection. It is the sectional side view which cut | disconnected the detection apparatus shown in FIG. 38 by XZ plane. 1 is a side sectional view of a capacitive detection device 200 to which the present invention can be applied. FIG. 37 is a top view of the strain body 210 in the detection apparatus shown in FIG. 36.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Piezoelectric element 11 ... Center part 12 ... Flexible part 13 ... Peripheral part 15 ... Circular groove 31-38 ... Q / V conversion circuit 41-43 ... Calculator 110 ... Vibrator 111, 112 ... Piezoelectric element 120 ... Object 130 ... vibrator 141 ... X-axis direction excitation means 142 ... Y-axis direction excitation means 143 ... Z-axis direction excitation means 151 ... X-axis direction force detection means 152 ... Y-axis direction force detection means 153 ... Z-axis direction force detection means 161 ... X-axis direction signal separation means 162 ... Y-axis direction signal separation means 163 ... Z-axis direction signal separation means 171 to 173 ... Acceleration calculation means 181 to 183 ... Angular velocity calculation means 200 ... Capacitive detection device 210 ... Strain body 211 ... Central part 212 ... Flexible part 213 ... Peripheral part 220 ... Vibrator 230 ... Base 240 ... Base substrate 250 ... Cover plate A, A1 to A8, A11 to A14, A21 to A24 ... Upper electrode B ... Lower electrode E ... Envelopes E0, E1-E4, E10, E20 ... Upper electrodes F1-F5 ... Lower electrodes m1-m8 ... Reference point O ... Origin P ... Center of gravity P1-P9 ... Inflection points Q1-Q9 ... Dividing lines Q12-Q89 ... Reference lines Tx, Ty, Tz ... output terminals

Claims (10)

An apparatus for detecting acceleration in a first axis direction and angular velocity about a second axis in a three-dimensional coordinate system,
A vibrator with mass,
Excitation means for oscillating the vibrator in a third axis direction in the three-dimensional coordinate system at a sufficiently high frequency that can be identified with respect to the frequency of the acceleration and angular velocity to be detected;
Force detecting means for detecting a force in the first axial direction applied to the vibrator;
Signal detection means for separating a bias component and an amplitude component for the detection signal obtained by the force detection means,
Acceleration calculating means for obtaining acceleration in the first axial direction based on the bias component;
Angular velocity calculating means for obtaining an angular velocity about the second axis based on the amplitude component;
A device for detecting both acceleration and angular velocity. A device for detecting an acceleration in each axial direction of a first axis, a second axis, and a third axis and an angular velocity around each axis in a three-dimensional coordinate system,
A vibrator with mass,
First excitation means for oscillating the vibrator in the first axial direction at a sufficiently high frequency that can be identified with respect to the frequency of the acceleration and angular velocity to be detected;
Second excitation means for oscillating the vibrator in the second axial direction at a sufficiently high frequency that can be identified with respect to the frequency of acceleration and angular velocity to be detected;
Third excitation means for oscillating the vibrator in the third axis direction at a sufficiently high frequency that can be identified with respect to the frequency of the acceleration and angular velocity to be detected;
First force detection means for detecting a force in the first axial direction applied to the vibrator;
Second force detection means for detecting a force in the second axial direction applied to the vibrator;
Third force detecting means for detecting a force in the third axial direction applied to the vibrator;
A first signal separation means for separating a bias component and an amplitude component for the first detection signal obtained by the first force detection means;
A second signal separation means for separating a bias component and an amplitude component for the second detection signal obtained by the second force detection means;
A third signal separation means for separating a bias component and an amplitude component for the third detection signal obtained by the third force detection means;
First acceleration calculation means for obtaining acceleration in the first axial direction based on a bias component for the first detection signal;
Second acceleration calculation means for obtaining an acceleration in the second axial direction based on a bias component for the second detection signal;
Third acceleration calculation means for obtaining acceleration in the third axial direction based on a bias component for the third detection signal;
The second excitation means is driven to vibrate the vibrator in the second axial direction. Based on the amplitude component of the first detection signal obtained in this state, the vibration around the third axis is obtained. First angular velocity calculation means for obtaining angular velocity;
The third excitation means is driven to vibrate the vibrator in the third axis direction. Based on the amplitude component of the second detection signal obtained in this state, the vibration around the first axis is obtained. A second angular velocity calculating means for obtaining an angular velocity;
The first excitation means is driven to vibrate the vibrator in the first axial direction. Based on the amplitude component of the third detection signal obtained in this state, the vibration around the second axis is obtained. A third angular velocity calculating means for obtaining an angular velocity;
A device for detecting both acceleration and angular velocity. A device for detecting an acceleration in each axial direction of a first axis, a second axis, and a third axis and an angular velocity around each axis in a three-dimensional coordinate system,
A vibrator with mass,
First excitation means for oscillating the vibrator in the first axial direction at a sufficiently high frequency that can be identified with respect to the frequency of the acceleration and angular velocity to be detected;
Second excitation means for oscillating the vibrator in the third axis direction at a sufficiently high frequency that can be identified with respect to the frequency of the acceleration and angular velocity to be detected;
First force detection means for detecting a force in the first axial direction applied to the vibrator;
Second force detection means for detecting a force in the second axial direction applied to the vibrator;
Third force detecting means for detecting a force in the third axial direction applied to the vibrator;
A first signal separation means for separating a bias component and an amplitude component for the first detection signal obtained by the first force detection means;
A second signal separation means for separating a bias component and an amplitude component for the second detection signal obtained by the second force detection means;
A third signal separation means for separating a bias component and an amplitude component for the third detection signal obtained by the third force detection means;
First acceleration calculation means for obtaining acceleration in the first axial direction based on a bias component for the first detection signal;
Second acceleration calculation means for obtaining an acceleration in the second axial direction based on a bias component for the second detection signal;
Third acceleration calculation means for obtaining acceleration in the third axial direction based on a bias component for the third detection signal;
The second excitation means is driven to vibrate the vibrator in the third axial direction, and based on the amplitude component of the first detection signal obtained in this state, the vibration around the second axis First angular velocity calculation means for obtaining angular velocity;
The first excitation means is driven to vibrate the vibrator in the first axis direction. Based on the amplitude component of the second detection signal obtained in this state, the vibration around the third axis is obtained. The angular velocity is obtained, and the second excitation means is driven to vibrate the vibrator in the third axial direction. Based on the amplitude component of the second detection signal obtained in this state, the second A second angular velocity calculating means for obtaining an angular velocity around one axis;
A device for detecting both acceleration and angular velocity. A device for detecting an acceleration in a first axial direction and an angular velocity around the first axis, and an acceleration in a second axial direction and an angular velocity around the second axis in a three-dimensional coordinate system,
A vibrator with mass,
Excitation means for oscillating the vibrator in a third axis direction in the three-dimensional coordinate system at a sufficiently high frequency that can be identified with respect to the frequency of the acceleration and angular velocity to be detected;
First force detection means for detecting a force in the first axial direction applied to the vibrator;
Second force detection means for detecting a force in the second axial direction applied to the vibrator;
A first signal separation means for separating a bias component and an amplitude component for the first detection signal obtained by the first force detection means;
A second signal separation means for separating a bias component and an amplitude component for the second detection signal obtained by the second force detection means;
First acceleration calculation means for obtaining acceleration in the first axial direction based on a bias component for the first detection signal;
Second acceleration calculation means for obtaining an acceleration in the second axial direction based on a bias component for the second detection signal;
First angular velocity calculation means for obtaining an angular velocity about the second axis based on an amplitude component of the first detection signal;
Second angular velocity calculation means for obtaining an angular velocity about the first axis based on an amplitude component of the second detection signal;
A device for detecting both acceleration and angular velocity. In the apparatus in any one of Claims 1-4,
The signal separation means extracts each inflection point of the detection signal, and has a signal value obtained by averaging the signal values of these two inflection points at an intermediate position on the time axis of two adjacent inflection points. Both acceleration and angular velocity are characterized in that a signal obtained by obtaining a point and connecting the obtained reference points is used as a bias component, and a signal corresponding to the difference between the detection signal and the bias component is used as an amplitude component. Detecting device. In the apparatus in any one of Claims 1-4,
Acceleration and angular velocity characterized in that the acceleration calculation means obtains the acceleration α by applying the calculation formula f = m · α based on the detected bias component f of the force and the mass m of the vibrator. A device that detects both. In the apparatus in any one of Claims 1-4,
The angular velocity calculation means calculates F = 2m · v · ω based on the detected force amplitude component F, the mass m of the vibrator, and the instantaneous speed v of the vibrator estimated from the operating state of the excitation means. An apparatus for detecting both an acceleration and an angular velocity, characterized in that an angular velocity ω is obtained by applying the following arithmetic expression. A vibrator with mass,
Excitation means for vibrating the vibrator;
Force detecting means for detecting force applied to the vibrator based on acceleration and angular velocity;
A signal separation means for separating a detection signal obtained by the force detection means into a first signal component caused by acceleration and a second signal component caused by angular velocity;
Output means for outputting an acceleration detection value based on the first signal component and outputting an angular velocity detection value based on the second signal component;
A device for detecting both acceleration and angular velocity. The apparatus according to claim 8.
An apparatus for detecting both acceleration and angular velocity, wherein the excitation means vibrates the vibrator at a sufficiently high frequency that can be discriminated with respect to the frequency of the acceleration and angular velocity to be detected. The device according to claim 8 or 9,
An apparatus for detecting both acceleration and angular velocity, wherein the signal separation means separates the first signal component and the second signal component by utilizing the difference in frequency.