JP2005147978A - Gyroscope device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive and precise gyroscope device. <P>SOLUTION: A magnet 6 is fixed to a tip of an elastic wire 5, the other end is clamped with a clamping body to prepare a two-dimensional oscillator 10. A driving chip coil 7 is provided to generate an x-axis-directional magnetic field in a periphery of the magnet 6, and a detecting chip coil 8 is provided to detect a y-axis-directional displacement of the magnet 6 along a y-axis direction. An alternating magnetic field is generated from the driving chip coil 7 to vibrate linearly the two-dimensional oscillator 10 only along an x-axis direction. When a rotation (angular velocity ω) around a z-axis as the center is applied under this condition, Coriolis force proportional to the angular velocity ω acts along a direction right-angled to a vibration direction, and resultingly the linear vibration gets to elliptic vibration. A phase change of a detection signal with respect to a driving signal is detected at this time by the detecting chip coil 8. In particular, the phase change is counted by a quartz clock. The angular velocity ω is detected highly precisely and sensitively when a resonance frequency of the two-dimensional oscillator 10 is brought into one hundred and several tens of Hz, and when a quartz clock frequency is brought into several tens of MHz. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a gyro device that detects an angular velocity based on a Coriolis force acting on a vibrating object during rotation. In particular, the present invention relates to a gyro apparatus that forms a two-dimensional vibrator by providing a magnet on an upper part of an elastic line and fixing the lower part of the elastic line, and detects an angular velocity from a change in trajectory of the two-dimensional vibrator accompanying rotation. The present invention can be applied to a gyro apparatus that detects rotation of a posture of a moving object such as an artificial satellite, an aircraft, a ship, and an automobile.

  Conventionally, as a gyro device for detecting an angular velocity, for example, a vibration gyro device disclosed in JP-A-2-223817 is well known. This vibration gyro device is shown in FIGS. FIG. 8 is a perspective view showing a gyro configuration, and FIG. 9 is an explanatory diagram for explaining a driving method and a detecting method of the gyro device. As shown in FIG. 8, in the conventional gyro device, a vibrating body 100 is formed by processing a constant elastic metal such as an Elinba alloy into a substantially regular triangular prism shape, and a ridge line portion near a node point of the vibrating body 100 is formed. The structure is supported by the support member 107. Further, as shown in FIG. 9, piezoelectric elements 102a, 102b, and 102c having electrodes on both sides are fixed to each side of the vibrating body 100 with an adhesive or the like. The piezoelectric element 102a and the piezoelectric element 102b are for driving and signal detection for driving the vibrating body 100, and the piezoelectric element 102c is for feedback of the oscillation circuit 104 shown below.

  In the above configuration, when a driving signal is output from the oscillation circuit 104, the vibrating body 100 bends and vibrates so that the formation surface of the piezoelectric element 102c is bent in the longitudinal direction. In this state, when rotation is applied about the longitudinal axis of the vibrating body 100, the vibration direction of the vibrating body 100 changes due to the Coriolis force, and an output difference corresponding to the change occurs between the piezoelectric elements 102a and 102b. This vibrating gyroscope device is configured to detect the Coriolis force applied to the vibrating body 100 by measuring the output difference, that is, the angular velocity proportional thereto.

  In addition, for example, there is a vibration gyro disclosed in Japanese Patent Publication No. 10-170279 and a vibration gyro disclosed in Japanese Patent Publication No. 2000-199713. In this example, a piezoelectric element is bonded to a metal tuning fork. These conventional examples have a configuration in which a piezoelectric element is used to vibrate a metal body, and the distortion of the metal generated by the Coriolis force due to rotation is detected by the piezoelectric element. Other examples include a tuning fork type piezoelectric gyro sensor disclosed in Japanese Patent Publication No. 2000-065579 and a tuning fork type piezoelectric gyro disclosed in Japanese Patent Publication No. 11-281369. These have a structure in which a piezoelectric element itself is processed into a tuning fork shape to form a vibrating body, and distortion caused by Coriolis force is detected by a voltage appearing in the piezoelectric element.

Recently, there is a gyro sensor manufactured using silicon micromachining. For example, there is a gyro sensor disclosed in Japanese Patent Application Laid-Open No. 11-142157. This is a structure in which a silicon substrate is dug into a hollow structure using a semiconductor anisotropic etching technique, and a central mass portion is supported by beam portions at both ends. An electrode is formed in the lower part of the mass part, and a capacitor is formed by the mass part and the electrode. A piezoelectric element (thin film) is formed on the beam portion. A voltage having a predetermined frequency is applied to resonate in the surface direction (z-axis direction) with an electrostatic force, and the Coriolis force accompanying the rotation is detected by a piezoelectric element formed on the beam portion. In some cases, the displacement of the mass portion due to the Coriolis force is detected by a capacitor electrode formed to face the side surface of the mass portion, that is, by a change in capacitance thereof.
JP-A-2-223817 Japanese Patent Publication No. 10-170279 Japanese Patent Publication No. 2000-199713 Japanese Patent Publication No. 2000-065579 Japanese Patent Publication No. 11-281369 Japanese Patent Publication No. 11-142157

  However, the conventional gyro sensor using a piezoelectric element has the following problems. For example, the performance of a piezoelectric element varies greatly with changes in temperature. For example, the electromechanical conversion efficiency may change from several tens of percent to several tens of percent due to temperature changes. Therefore, a gyro sensor using a piezoelectric element does not output an angular velocity stably with respect to a temperature change. There is also a problem that the output drifts even at rest due to temperature changes.

Further, in the configuration in which the vibrating body such as a metal is driven by the piezoelectric element, the vibration due to the harmonics of the driving piezoelectric element itself propagates to the detecting piezoelectric element through the housing or the like. In order to avoid this, various support structures or electronic circuits are usually added. That is, there is a problem that the assembly process becomes complicated. In addition, the configuration in which the piezoelectric element is attached to the metal body has a problem that when the piezoelectric element is driven for a long period of time, the piezoelectric element partially peels from the metal body due to expansion and contraction of the piezoelectric element. That is, there is a problem that it is not suitable for long-term use.
In addition, the piezoelectric element sensitively detects external vibration. Therefore, since detection of low-speed rotation is included in noise due to external vibration, there is a problem that it is difficult to detect.
Moreover, the performance of the piezoelectric element varies depending on its composition, shape, and processing accuracy. That is, there is a problem that the performance varies depending on individual products.

  Further, when a vibration type gyro sensor is manufactured by micromachining, for example, several square mm of silicon (surface layer) is used, so that the mass portion becomes extremely small. For example, it is several mg to several μg. That is, even if driven at a high frequency, the Coriolis force is proportional to the mass of the mass portion, so that the Coriolis force becomes small. Therefore, there is a problem that the mass portion is displaced little by the Coriolis force during low-speed rotation, and the angular velocity at low speed is difficult to detect.

The present invention has been made to solve the above-described problems, and an object of the present invention is to form a two-dimensional vibrator with an elastic line and a magnet having a predetermined mass, and to vibrate the two-dimensional vibrator with an alternating magnetic field. The change in the trajectory of the magnet due to the Coriolis force during rotation is made large, and thereby the angular velocity is detected with high sensitivity.
In addition, the phase change of the detection signal accompanying the change of the orbit is counted with a quartz clock, and the angular velocity is detected with higher accuracy than before.

It is another object of the present invention to provide a gyro device that uses an elastic wire of a two-dimensional vibrator as a wire having a low thermal expansion coefficient and reduces the influence of temperature change. It is another object of the present invention to provide a gyro device that can reduce the drift at rest.
Further, the resonance frequency can be adjusted by adjusting the elastic line length of the two-dimensional vibrator, thereby reducing the variation among products. Further, the elastic line is set in the holder groove and pressed with a predetermined pressure to separate the resonance spectrum and facilitate initial linear vibration. Also, the assembly is facilitated by adopting a structure in which the elastic wire is set in the holder groove.
Further, the gyro can be miniaturized by driving the two-dimensional vibrator with a chip coil and making it possible to detect the orbital change of the magnet with the chip coil. In addition, it is to save power.
It should be noted that the above objects are individual objects achieved by each invention and should not be construed as achieving each object.

  The gyro apparatus according to claim 1 is a gyro apparatus that obtains an angular velocity based on a Coriolis force acting on a vibrating object during rotation, and includes an elastic line, a magnet fixed to the front end of the elastic line, and a rear end of the elastic line. Orbit change detection means comprising a two-dimensional vibrator comprising a holder for fixing the magnet, a magnetic field generating means for minutely vibrating the magnet in a predetermined direction, and a trajectory change detecting means for detecting a trajectory change of the magnet due to the Coriolis force. The angular velocity is calculated from the trajectory change related value detected by the means.

A gyro device according to a second aspect is the gyro device according to the first aspect, wherein the elastic line is an elastic line having a constant elastic modulus or an elastic line having a low thermal expansion coefficient.
The gyro device according to claim 3 is the gyro device according to claim 1 or 2, wherein the rear end portion of the two-dimensional vibrator has different resonance frequencies in different biaxial directions depending on the holder. As described above, it is characterized in that it is clamped from one direction with a predetermined stress, and the clamping direction by the holder coincides with the magnetic field generation direction by the magnetic field generation means or the detection direction of the trajectory change detection means.

The gyro device according to claim 4 is the gyro device according to claim 3, wherein the holder is composed of a holder receiver and a holder presser, and the elastic wire rear end portion has a predetermined depth on the upper surface of the holder receiver. The elastic groove is arranged so that the side surface of the elastic line protrudes from the groove, and the predetermined stress is determined by being pressed and clamped by the holder receiver and the holder press.
Further, the gyro device according to claim 5 is the gyro device according to any one of claims 1 to 4, wherein the magnetic field generating means has a fine ferrite or a minute electromagnetic soft iron as a core, and a conductor is provided in the core. It is characterized by comprising a wound chip coil.

The gyro device according to claim 6 is the gyro device according to any one of claims 1 to 5, wherein the trajectory change detecting means detects the displacement of the elliptical vibration of the magnet in the short axis direction due to rotation. It is an optical displacement detection means for optical detection or a magnetic displacement detection means for magnetic detection.
The gyro apparatus according to claim 7 is the gyro apparatus according to any one of claims 1 to 6, wherein the orbit change-related value is a change in amplitude of a detection signal by the orbit change detecting means. It is characterized by.

The gyro apparatus according to claim 8 is the gyro apparatus according to any one of claims 1 to 6, wherein the orbit change-related value is a phase change of a detection signal by the orbit change detecting means. It is characterized by.
The gyro apparatus according to claim 9 is the gyro apparatus according to claim 8, wherein the phase change is a phase difference between a drive signal for driving the magnetic field generating means and a detection signal detected by the orbit change detecting means. Is obtained by counting with a high-frequency clock every predetermined time.
The gyro apparatus according to claim 10 is the gyro apparatus according to any one of claims 1 to 9, wherein the two-dimensional vibrator, the magnetic field generating means, and the orbit change detecting means are configured to generate an external magnetic field. It is characterized in that it is installed in a magnetic shielding housing to avoid it.

  The gyro apparatus according to claim 1 is a gyro apparatus that obtains an angular velocity based on a Coriolis force acting on a vibrating object during rotation, and includes an elastic line, a magnet fixed to the front end of the elastic line, and a rear end of the elastic line. Orbit change detection means comprising a two-dimensional vibrator comprising a holder for fixing the magnet, a magnetic field generating means for minutely vibrating the magnet in a predetermined direction, and a trajectory change detecting means for detecting a trajectory change of the magnet due to the Coriolis force. The angular velocity is calculated from the trajectory change related value detected by the means. The gyro apparatus of the present invention is a so-called rate gyro that detects angular velocity based on Coriolis force acting on a vibrating object and a moving object during rotation.

  First, an elastic wire is prepared, and a magnet is fixed to the elastic wire tip. Then, a rear end portion of the elastic line is fixed with a holder to form a two-dimensional vibrator capable of minute vibrations in two directions. The two-dimensional vibrator means a vibrator that can vibrate on an xy plane perpendicular to the z-axis when the axial direction of the elastic line is the z-axis. For example, magnetic field generating means for minutely vibrating the magnet in a predetermined direction is provided around the magnet. The magnetic field generating means is, for example, a minute coil, and generates an alternating magnetic field that matches the natural frequency of the two-dimensional vibrator, for example. As a result, the two-dimensional vibrator vibrates linearly or elliptically in a predetermined direction (the direction of the alternating magnetic field). In this state, when the gyro device rotates about the z-axis, a Coriolis force proportional to the outer product of the angular velocity and the vibration velocity and the mass of the magnet acts on the magnet. As a result, the magnet is displaced to the right or left in the traveling direction, and as a result, its trajectory changes.

  When the magnet is initially vibrating linearly by the alternating magnetic field, it changes to elliptical vibration. That is, the linear trajectory changes to an elliptical trajectory. If the magnet is initially elliptically vibrating, its ellipticity changes. That is, the magnet trajectory changes. In the present invention, the trajectory change related value related to the trajectory change is detected by the trajectory change detecting means. The orbital change related value is a value correlated with the angular velocity, and is all related values related to the orbital change such as a short axis length change, ellipticity change, elliptical perimeter change, and elliptical area change of the elliptical orbit. For example, if the trajectory change detecting means is constituted by a minute coil, a short axis length change of an elliptical trajectory can be easily detected by a voltage change by electromagnetic induction. That is, the angular velocity can be easily detected.

  A conventional gyro apparatus uses a piezoelectric element that is ceramic or silicon. Therefore, they may be damaged by impact or the like. According to the present invention, a two-dimensional vibrator that vibrates minutely using an elastic line typified by metal is used. Therefore, it can be set as the gyro apparatus robust to an impact or the like. Further, in comparison with a gyro device using micromachining technology, the mass for sensing Coriolis force is used as the mass of the magnet in the present invention. Therefore, it can be made larger than the conventional silicon gyro apparatus. That is, the angular velocity can be detected with higher sensitivity.

  A gyro device according to a second aspect is the gyro device according to the first aspect, wherein the elastic line is an elastic line having a constant elastic modulus or an elastic line having a low thermal expansion coefficient. The elastic line having a constant elastic modulus is, for example, an Elinba alloy. The elastic line having a low thermal expansion coefficient is, for example, an Invar alloy. Both elastic lines have a small temperature dependence of their elastic modulus. That is, since the elastic coefficient change with respect to the temperature change is small, the resonance frequency change due to the elastic coefficient change can be suppressed. Therefore, according to the gyro apparatus of the present invention, the angular velocity can be detected stably even with respect to a temperature change.

  The gyro device according to claim 3 is the gyro device according to claim 1 or 2, wherein the rear end portion of the two-dimensional vibrator has different resonance frequencies in different biaxial directions depending on the holder. Thus, the holder is clamped with a predetermined stress from the one direction, and the clamping direction of the holder coincides with the magnetic field generation direction by the magnetic field generation means or the detection direction of the trajectory change detection means.

  The biaxial directions with different elastic lines are the x-axis direction and the y-axis perpendicular to the z-axis when the axial direction of the elastic line is the z-axis. The rear end portion of the elastic line is held in a state where a predetermined stress is received in the y-axis direction, for example. Therefore, the elastic line cross section at that point is microscopically deformed into an ellipse. Due to the shape effect of the deformed cross section or the internal stress effect, the elastic coefficient of the elastic line differs depending on the stress direction (y-axis direction) and its perpendicular direction (x-axis direction). Further, since the elastic coefficient relates to the natural frequency of the system, the natural frequency also varies depending on the direction. That is, the resonance mode is spectrally separated by the x-axis direction and the y-axis direction. Therefore, when the magnetic field generated by the magnetic field generating means coincides with the stress direction, resonance can occur in the stress direction stably without crosstalk. For example, if an alternating magnetic field is generated in the x-axis direction by the magnetic field generating means, the two-dimensional vibrator can be stably oscillated linearly in the x-axis direction. And when rotating, the trajectory changes in the y-axis direction. That is, it is possible to detect a change in trajectory due to Coriolis force stably. The magnetic field generated by the magnetic field generating means and the stress direction by the holder may be orthogonal. In this case, the detection direction of the trajectory change detection means coincides with the stress direction of the holder. That is, the x-axis direction and the y-axis direction may be interchanged. In this way, the same effect can be obtained.

  The gyro device according to claim 4 is the gyro device according to claim 3, wherein the holder is composed of a holder receiver and a holder presser, and the elastic wire rear end portion has a predetermined depth on the upper surface of the holder receiver. The side surface of the elastic line is disposed in the formed groove so that the side surface protrudes from the groove, and the predetermined stress is determined by being pressed and clamped by the holder receiver and the holder presser. In this configuration, the rear end portion of the elastic line is pressed and clamped by the holder receiver and the holder presser. Accordingly, the rear end portion of the elastic line is fixed with a predetermined stress corresponding to the depth of the groove provided on the upper surface of the holder receiver and the diameter of the elastic line. Therefore, a constant predetermined stress can be applied only by an operation of pressing and holding the rear end portion of the elastic line by the holder receiver and the holder presser at the time of assembly. Since the separation width of the resonance spectrum is determined by this stress, variation among products is reduced. Therefore, it is possible to easily provide a gyro device having stable characteristics.

  Further, the gyro device according to claim 5 is the gyro device according to any one of claims 1 to 4, wherein the magnetic field generating means has a fine ferrite or a minute electromagnetic soft iron as a core, and a conductor is provided in the core. It is formed of a wound chip coil. When an alternating current is supplied to these chip coils, an alternating magnetic field is generated from both ends of the chip coil. Therefore, alternating torque can be easily applied to the magnet. Therefore, the gyro device according to any one of claims 1 to 4 can be easily realized. The chip coil is several millimeters square. Therefore, space is saved and the gyro device can be miniaturized.

  The gyro device according to claim 6 is the gyro device according to any one of claims 1 to 5, wherein the trajectory change detecting means detects the displacement of the elliptical vibration of the magnet in the short axis direction due to rotation. An optical displacement detection means for optical detection or a magnetic displacement detection means for magnetic detection is formed. The orbit change detecting means is installed in a direction perpendicular to the initial linear vibration (no rotation). Therefore, for example, if an optical displacement detection unit such as a proximity sensor including a light projecting unit and a light receiving unit is provided, it is possible to easily detect the displacement in the short axis direction accompanying the rotation. If the optical displacement detection means is used, the influence of electromagnetic noise is avoided, so that the angular velocity can be detected with high accuracy. The orbit change detecting means may be a magnetic displacement detecting means such as a minute coil. If the magnet passes near the minute coil, a voltage is generated at the terminal of the minute coil by electromagnetic induction. In particular, if a small coil is installed in the short axis direction, the displacement in the short axis direction can be detected efficiently.

The gyro apparatus according to claim 7 is the gyro apparatus according to any one of claims 1 to 6, wherein the change in amplitude of the detection signal by the orbit change detecting means is used as the orbit change-related value. ing. The Coriolis force is an apparent force that works when a moving object is rotated and is expressed as follows.
fc = 2 mV × ω (1)
fc: Coriolis force m: mass V: velocity vector ω: angular velocity vector As can be seen from the equation (1), the Coriolis force fc is obtained when an angular velocity ω is generated when an object of mass m is moving at a velocity V. The magnitude is generated in proportion to the mass m, the velocity V, and the angular velocity ω perpendicular to the moving direction and the direction of the rotation axis of the angular velocity ω. In the present invention, since the two-dimensional vibrator reciprocates, the trajectory change detection means detects the movement with a sine wave signal. That is, when the angular velocity is high, the displacement of the mass (magnet) due to the Coriolis force is also large, so that the amplitude of the detection signal by the trajectory change detection means is also large. Conversely, when the angular velocity is small, the amplitude of the detection signal is also small. Therefore, if the trajectory change related value is the signal amplitude of the detection signal, the magnitude of the acceleration at that time can be easily estimated.

  Further, the gyro apparatus according to claim 8 is the gyro apparatus according to any one of claims 1 to 6, wherein the phase change of the detection signal by the orbit change detecting means is used as the orbit change related value. ing. When rotation acts on a two-dimensional vibrator that is oscillating linearly, the trajectory of the two-dimensional vibrator changes from linear vibration to elliptical vibration. At this time, the phase of the detection signal with respect to the reference signal (drive signal) also changes due to a change in the trajectory. For example, the phase is delayed when rotating right, and the phase is advanced when rotating left. Therefore, if this phase change is used as the orbit change-related value, the magnitude of the angular velocity can be easily estimated based on the magnitude of the phase change. Furthermore, the direction of rotation can be easily determined from the direction of increase / decrease of the phase. That is, the angular velocity can be detected by a vector quantity.

  The gyro apparatus according to claim 9 is the gyro apparatus according to claim 8, wherein the phase change is a level of a drive signal for driving the magnetic field generating means and the detection signal detected by the orbit change detecting means. The phase difference is obtained by counting with a high-frequency clock every predetermined time. If the phase difference between the drive signal and the detection signal is counted with a high-frequency clock such as a quartz clock every predetermined time and the change is calculated, the angular velocity can be measured with high accuracy. Therefore, a highly accurate gyro device can be realized.

  The gyro apparatus according to claim 10 is the gyro apparatus according to any one of claims 1 to 9, wherein the two-dimensional vibrator, the magnetic field generating means, and the orbit change detecting means are configured to generate an external magnetic field. To avoid it, it is installed in a magnetic-shielding housing. Since the two-dimensional vibrator has a magnet at the tip, it is affected by an external magnetic field (disturbance magnetic field). The magnetic field generating means is also affected by the external magnetic field. Further, the same applies to the case where the orbit change detecting means is a magnetic displacement detecting means. Therefore, the two-dimensional vibrator, the magnetic field generating means, and the trajectory change detecting means are installed in a magnetic shielding case sealed with ferrite or the like. In this way, the influence of the external magnetic field is reduced, and the angular velocity can be detected with higher accuracy.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  FIG. 1 shows a gyro apparatus of the present invention. The figure is a block diagram. The gyro apparatus of the present invention includes a two-dimensional vibrator 10 comprising an elastic wire 5, a magnet 6 fixed to the tip of the elastic wire 5, a holder receiver 2 for fixing the rear end of the elastic wire 5, and a holder holder 3. The driving chip coil 7 is a magnetic field generating means that is provided around the magnet 6 to vibrate the magnet 6 in a predetermined direction, and the detecting chip coil is a trajectory change detecting means for detecting a trajectory change of the magnet 6 due to the Coriolis force. 8. The driving chip coil 7 and the detection chip coil 8 are fixed to a chip coil holder 9, and the chip coil holder 9 is fixed to the substrate 1. The two-dimensional vibrator 10 is installed on the substrate 1 by a holder including a holder receiver 2 and a holder holder 3. The gyro apparatus according to the present embodiment has a weight of about 6 g and is suitable for mobile devices such as aircraft and artificial satellites that are required to be lighter.

  In the above-described configuration, the rear end portion of the elastic wire 5 is disposed so as to protrude to the groove provided on the side surface of the holder receiver 2 and is sandwiched between the holder pressers 3. A predetermined stress is applied and fixed by the screw 4. At this time, the cross section of the elastic line 5 at that point is microscopically deformed into an ellipse by stress. Due to this deformation effect, the elastic coefficient of the elastic wire 5 differs depending on the stress direction (y-axis direction in the figure) and its perpendicular direction (x-axis direction). Since the elastic coefficient relates to the natural frequency of the mechanical system, the natural frequency also varies depending on the direction. That is, the resonance mode can be easily separated in the spectrum as shown in FIG. 2 simply by applying a predetermined stress by the holder receiver 2 and the holder holder 3. This is the knowledge we have shown in the projection apparatus disclosed in Japanese Patent No. 2892641. In the configuration shown in FIG. 1, when several mA to several tens of mA is applied to the terminal of the driving chip coil 7 at a predetermined frequency (for example, fx = 137 Hz) indicated by an arrow in FIG. Occurs and the two-dimensional vibrator 10 resonates. At this time, since there is almost no crosstalk with the y-axis direction spectral component, there is no displacement in the y-axis direction of the two-dimensional vibrator 10, and the linear vibration is stable only in the x-axis direction. Therefore, stability during no rotation (angular velocity = 0) is guaranteed. In this embodiment, an Elinba alloy having a constant elastic modulus is used for the elastic wire 5. Therefore, the resonance frequency hardly changes even when the temperature changes. Therefore, the two-dimensional vibrator 10 of this embodiment stably oscillates linearly with respect to temperature changes. For the elastic wire 5, not only an Elinba alloy but also an Invar alloy can be used. Invar alloys also have substantially constant elastic properties. Therefore, there is almost the same effect as the Elinba alloy.

In this state, when the two-dimensional vibrator 10 rotates at the angular velocity ω with the elastic line axis direction, that is, the z-axis direction as the central axis, the Coriolis force fc (= 2 mVω) acts on the magnet 6 according to the equation (1). Displacement in the y-axis direction. That is, the trajectory of the magnet 6 changes. As a result, as shown in FIG. 3, the linear vibration (FIG. 3A) when the angular velocity ω = 0 is changed to a counterclockwise elliptical vibration (FIG. 3B) or a clockwise elliptical vibration (FIG. 3C). Change. That is, when device gyro apparatus of the present embodiment is mounted to rotate, for example, an angular velocity vector is in the direction penetrating on the paper surface from the bottom, left for example ellipticity is changed according to the magnitude of the angular velocity omega _L It becomes a round elliptical vibration (FIG. 3B). Further, when the angular velocity vector in the reverse is a direction penetrating from top to bottom paper, the angular velocity ω according to the size for example clockwise elliptical vibration ellipticity is changed in _R (Figure 3 (c)).

At this time, the angular velocity can be grasped with various trajectory change-related values. The orbit change-related value is, for example, a phase change (described later) when the orbit changes, a short axis length change of an elliptic orbit, an ellipticity change, an ellipse circumference change, an elliptic area change, or the like. In this embodiment, the phase change is taken up in order to enable highly accurate detection. When the trajectory of the two-dimensional vibrator 10 changes from linear vibration to elliptical vibration, the phase of the detection signal with respect to the drive signal (reference signal) of the two-dimensional vibrator 10 changes. This is because the approach timing of the magnet 6 to the detection chip coil 8 changes as the trajectory changes. That is, as shown in FIG. 4, when the signal given to the driving chip coil 7 for driving the magnet 6 is used as a reference signal, when the gyro device of this embodiment is rotated clockwise, the detection signal is in response to the reference signal (a). So that the phase is increased (the phase is delayed) (detection signal (b)). In other words, changing from a phase difference phi ₀ to the phase difference phi _R. In this case, (φ _R −φ ₀ ) is proportional to the angular velocity ω _R. Conversely, when the gyro device is rotated counterclockwise, the detection signal is displaced so that the phase difference with respect to the reference signal (a) decreases (phase advances) (detection signal (d)). In other words, changing from a phase difference phi ₀ to the phase difference phi _L. In this case, (φ ₀ −φ _L ) is proportional to the angular velocity ω _L.

  In this embodiment, this phase change is counted with a quartz clock in order to improve measurement accuracy. FIG. 5 shows the phase change detection circuit of this embodiment. The figure is a block diagram. The phase change detection circuit according to this embodiment includes a quartz clock 21, an AND circuit 22, a counter circuit 23, and a one-chip microcomputer 24. In this configuration, the phase change of the detection signal and the reference signal is counted with high sensitivity by the quartz clock 21 and the counter circuit 23. For example, if the reference signal and the detection signal are both about 137 Hz and the quartz clock is 16 MHz, the phase is divided by 110,000. That is, the angular velocity ω is counted with high sensitivity.

FIG. 6 shows a flowchart of the gyro apparatus of this embodiment. The phase measurement of the present embodiment is an interrupt program triggered by a rising edge of a detection signal digitized by a comparator (not shown), and is measured, for example, every about 7.3 msec. Note that the phase φ ₀ at the time of non-rotation is measured and stored in advance in a normal program. First, in step s10, the current phase φ is read. Next, the process proceeds to step s12, and the phase change φ _D = φ−φ ₀ is calculated. Next, in step s14, it is determined whether φ _D > 0. If phi _D> 0, the process proceeds to step s20 to the direction flag to 1 if That yes. The direction flag 1 is, for example, left rotation. Conversely, phi _D and the angular velocity to a positive value as the migration and φ _{D =} -φ _D to step s18 if _<0, and 0 the direction flag. The direction flag 0 is, for example, clockwise rotation. Then, the process proceeds to step s20, and the angular velocity ω _C is calculated by multiplying by the calibration constant k _C. Finally the process proceeds to step s22, and outputs a direction flag and the angular velocity omega _C.

  FIG. 7 shows the output result of the gyro device of this embodiment. This is an output result (phase change diagram) when the gyro device of the present embodiment is fixed to the rotary table with the z-axis facing upward, and the rotary table is rotated leftward at an angular velocity of 10 ° / sec. The vertical axis represents the phase value, and the horizontal axis represents the number of data corresponding to time. In FIG. 7, a part shows a stationary state, and b part shows a phase change when it is rotated counterclockwise at an angular velocity of 10 ° / sec. The phase value of about 58400 corresponds to π / 2. That is, the sensitivity (resolution) at this time is evaluated to be about 0.002 ° / sec per count.

(Modification)
The present invention can be implemented in various other forms. For example, in the above-described embodiment, the chip coil is assumed to have ferrite as a core and a conductor is wound around the outer periphery thereof. However, the core may not be particularly ferrite. For example, fine electromagnetic soft iron may be used. An air core may be used if the number of windings is large.

  In the above embodiment, the magnetic field generated by the magnetic field generating means (chip coil 7) and the stress directions by the holder receiver 2 and the holder presser 3 are orthogonal to each other, but these may be parallel. In this case, conversely, the detection direction of the trajectory change detection means (chip coil 8) and the stress direction by the holder receiver 2 and the holder presser 3 are orthogonal to each other. Such an arrangement may be adopted. Equivalent effect can be obtained.

In the above embodiment, the angular velocity is captured by the phase change of the detection signal, but this can also be captured by the amplitude change of the detection signal (sine curve) before digital conversion. This is because the elastic line 5 is considered as a flexure spring, and the relationship Δy = fc / k (k: spring constant) is established for the displacement amount Δy in the y-axis direction due to the Coriolis force fc in FIG. That is, the displacement amount Δy = 2Vmω / k relationship is established. Here, the displacement amount Δy means displacement in the minor axis (y-axis) direction of elliptical vibration (FIG. 3B). This is detected by a change in amplitude of the sine curve before digital conversion in the detection signal. Accordingly, the angular velocity ω can be detected by detecting this displacement amount Δy, that is, the amplitude change as a value related to the orbit change in the detection chip coil 8 applied in the y-axis direction. You may do this.
Of course, instead of the detection chip coil 8 which is a magnetic displacement detection means, a proximity sensor which is an optical displacement detection means for optically detecting the proximity of the two-dimensional vibrator 10 can be used for the displacement amount Δy. The proximity sensor is composed of, for example, a pair of optical fibers, and projects light from one optical fiber and receives light from the other optical fiber. If the proximity amount is large, the received light amount is increased. If the proximity amount is small, the received light amount is also small. If this is photoelectrically converted, the trajectory change of the two-dimensional vibrator 10 can be obtained by a sine curve (voltage). The angular velocity ω may be converted from the amplitude value of this sine curve. Equivalent results are obtained.

  In the above embodiment, the two-dimensional vibrator 10 is surrounded by the chip coil holder 9 made of aluminum, for example. In this case, the magnet 6, the driving chip coil 7, and the detection chip coil 8 may be affected by an external magnetic field. In such a case, although not shown, the entire gyro device is installed in a magnetic shielding case sealed with ferrite or the like. By doing so, the influence of the external magnetic field is reduced and the angular velocity can be detected stably.

1 is a structural diagram of a gyro device according to an embodiment of the present invention. The resonance spectrum figure of the two-dimensional vibrator which concerns on the gyro apparatus of this invention. The vibration state change figure of the two-dimensional vibrator concerning the gyro device of the present invention. The phase change figure of the detection signal and reference signal which concern on the gyro apparatus of this invention. The phase difference detection circuit diagram concerning the gyro apparatus of this invention. The flowchart which shows operation | movement of the gyro apparatus of the Example of this invention. The angular velocity detection result figure by the gyro apparatus which concerns on the Example of this invention. The mechanical structure figure of the conventional gyro apparatus. The block diagram including the electrical equipment part which concerns on the conventional gyro apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Board | substrate 2 ... Holder receiver 3 ... Holder presser 5 ... Elastic wire 6 ... Magnet 7 ... Chip coil for drive 8 ... Chip coil for detection 9 ... Chip coil holder 10 ... Two-dimensional vibrator

Claims (10)

A gyro device that detects angular velocity based on Coriolis force acting on a vibrating object during rotation,
A two-dimensional vibrator comprising an elastic line, a magnet fixed to the tip of the elastic line, and a holder for fixing the rear end of the elastic line;
Magnetic field generating means for minutely vibrating the magnet in a predetermined direction;
Orbit change detecting means for detecting orbit change of the magnet due to the Coriolis force,
The gyro apparatus characterized in that the angular velocity is calculated based on a trajectory change related value detected by the trajectory change detecting means.   The gyro apparatus according to claim 1, wherein the elastic line is an elastic line having a constant elastic modulus or an elastic line having a low thermal expansion coefficient.   The rear end portion of the two-dimensional vibrator is clamped with a predetermined stress from one direction so that the resonance frequencies of the two biaxial directions of the elastic lines differ by the holder, and the clamping direction by the holder is determined by the magnetic field generating means 3. The gyro apparatus according to claim 1, wherein the gyro device coincides with a magnetic field generation direction or a detection direction of the trajectory change detection means.   The holder includes a holder receiver and a holder presser, and the rear end of the elastic line is disposed in a groove formed at a predetermined depth on the upper surface of the holder receiver so that a side surface of the elastic line protrudes from the groove. 4. The gyro apparatus according to claim 3, wherein the predetermined stress is determined by being pressed and clamped by the holder receiver and the holder presser.   5. The gyro apparatus according to claim 1, wherein the magnetic field generation unit includes a chip coil in which a fine ferrite or a minute electromagnetic soft iron is used as a core, and a conductive wire is wound around the core. .   The trajectory change detecting means is an optical displacement detecting means for optically detecting a displacement in the minor axis direction of elliptical vibration of the magnet due to rotation, or a magnetic displacement detecting means for magnetically detecting. The gyro apparatus according to any one of claims 1 to 5.   The gyro apparatus according to any one of claims 1 to 6, wherein the orbit change related value is an amplitude change of a detection signal by the orbit change detecting means.   The gyro apparatus according to any one of claims 1 to 6, wherein the orbit change related value is a phase change of a detection signal by the orbit change detecting means.   The phase change is obtained by counting a phase difference between a drive signal for driving the magnetic field generating means and the detection signal detected by the trajectory change detecting means with a high frequency clock every predetermined time. The gyro apparatus according to claim 8. The said two-dimensional vibrator, the said magnetic field generation means, and the said orbit change detection means are installed in a magnetic-shielding housing | casing in order to avoid an external magnetic field, The any one of Claim 1 thru | or 9 characterized by the above-mentioned. A gyro device as described in 1.

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