JP2000028364A - Angular velocity sensor and its driving method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly sensitive oscillation-type angular velocity sensor and its driving method. SOLUTION: In an angular velocity sensor device, a drive amplitude comparing means 104, a drive voltage regulating means 105, an oscillating means 106, an amplifier 107, and a drive frequency setting means 108 are connected in a loop shape. The drive frequency setting means 108 changes the oscillation frequency of the oscillating means 106 into an initial drive frequency in the vicinity of the resonance frequency of an angular velocity sensor 101 and next gradually into a set frequency. The drive amplitude comparing means 104 compares the amplitude detected from a drive amplitude detecting means 103 with a set value A2. On the basis of the results of the comparison the drive voltage regulating means 105 controls and regulates the amplification factor of the amplifier 107 so that the dive amplitude obtained from the drive amplitude detecting means 103 may match with A2. The target amplitude A2 here is determined on the basis of an amplitude value in which a signal jumps at the time when the angular velocity sensor is driven in great amplitude.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Various gyroscopes (hereinafter referred to as gyroscopes) have been developed as sensors for detecting angular velocity. The types are roughly classified into a mechanical gyroscope, a fluid gas gyroscope, a vibrating gyroscope using vibration of a tuning element and a tuning fork, an optical fiber gyroscope and a ring laser gyroscope. The optical gyro detects the Sagnac effect, and the others detect the angular velocity using the Coriolis force, which is a manifestation of the law of conservation of angular momentum of the rotating body. Sensor is selected.

A vibration gyro-type angular velocity sensor is disclosed, for example, in Japanese Patent Application Laid-Open No. 61-77712. FIG. 9 is an explanatory view of the basic principle of this conventional vibration type angular velocity sensor, in which detection elements 901 and 902 are attached to the ends of excitation elements 903 and 904. Each element is composed of, for example, a piezoelectric bimorph, and a pair of an excitation element and a detection element forms a tuning fork.
This angular velocity sensor is an excitation element 90 near the root of the tuning fork.
3,904 by applying an AC voltage to the elements 901 and 90 for detection.
2 is caused to flexurally vibrate, and the angular velocity is detected using the piezoelectric effect from the Coriolis force applied perpendicularly to the surface of the detecting element.

Further, in recent years, the development of ultra-small angular velocity sensors formed by applying micromachining micromachining technology to materials such as single crystal silicon and quartz has been advanced. For example, a paper published by P. Greiff et al. (Silicon mono
lithic micromechanical gyroscope, Transducers'91,
pp. 966-969), one example of which is described. As the signal processing circuit, for example, Japanese Unexamined Patent Application Publication No. Hei 8-178665, "Driving Method of Vibrating Gyroscope",
No. 1810, "Control circuit of vibratory gyroscope"
And the like.

An angular velocity sensor for an automobile is used for controlling a chassis system or calculating an azimuth of a navigation system. However, the detected angular velocity sensor is a yaw direction, a roll direction, and a pitch direction. It is often an angular velocity (that is, a yaw rate) of (rotation in a plane horizontal to the ground about a vertical line). For example, four-wheel steering (4W
In the case of the chassis control as in S), the yaw rate is fed back to the control system as one of the attitude information of the vehicle, and is used to improve the attitude control performance.
In the case of a navigation system, it is used to calculate the turning angle of the vehicle by integrating the yaw rate over time. The angular velocity sensor usually used for a vehicle is an inexpensive piezoelectric vibrating gyroscope. There is an example in which an optical gyro has been put to practical use as a high-precision on-vehicle sensor.

[0006]

However, in order to mount electronic components on various devices such as in-vehicle applications, it is necessary to reduce the size of electronic components. In this case, the detection sensitivity of the angular velocity is also lowered at the same time, and there is a problem that it is very difficult to achieve both miniaturization and sensitivity.

SUMMARY OF THE INVENTION An object of the present invention is to provide a small and highly sensitive angular velocity sensor device and a method of driving the same in consideration of the above problems.

[0008]

According to a first aspect of the present invention, there is provided an angular velocity sensor, an oscillating means, and a first jump frequency at which the amplitude in the nonlinear resonance mode of the angular velocity sensor rapidly increases and a second jump frequency at which the amplitude sharply decreases. The initial drive frequency is set to a value less than the first jump frequency when the second jump frequency is higher than the first jump frequency.
When the second jump frequency is lower than the first jump frequency, the initial drive frequency is set to a value larger than the first jump frequency, and after the drive amplitude is increased by oscillation, the first and second jump frequencies are set. A drive frequency setting unit that sets a frequency to a set frequency between the frequencies, an amplifier that amplifies an output of the oscillation unit, a driving unit that excites a predetermined vibration to the angular velocity sensor based on an output of the amplifier, A drive amplitude detector that detects a drive vibration amplitude of the angular velocity sensor; a drive amplitude comparator that compares the amplitude obtained by the drive amplitude detector with a predetermined value; and a drive amplitude comparator that responds to the result of the drive amplitude comparator. And a drive voltage adjusting means for adjusting the amplification factor.

According to a second aspect of the present invention, there is provided an angular velocity sensor, an oscillating means, and a frequency of the oscillating means, wherein the amplitude in the nonlinear resonance mode of the angular velocity sensor is rapidly increased.
Comparing the jump frequency of the first jump frequency with the second jump frequency at which the amplitude decreases sharply. If the second jump frequency is higher than the first jump frequency, the initial drive frequency is set to a value less than the first jump frequency; When the second jump frequency is lower than the first jump frequency, the initial drive frequency is set to a value larger than the first jump frequency, and after the drive amplitude is increased by oscillation, the first and second jump frequencies are set. A drive frequency setting means for setting a frequency to a set frequency between; an amplifier for amplifying an output of the oscillating means; a driving means for exciting a predetermined vibration to the angular velocity sensor based on an output of the amplifier; Driving amplitude detecting means for detecting a driving vibration amplitude of the sensor; driving amplitude comparing means for comparing the amplitude obtained by the driving amplitude detecting means with a predetermined value of an amplitude having a non-linear characteristic; It is characterized in that and a driving frequency adjusting means for adjusting the oscillation frequency of the oscillation means according to the result of the width comparing means.

According to a third aspect of the present invention, there is provided a driving method for driving the angular velocity sensor device according to the first aspect, wherein the frequency of the oscillating means is increased by a first amplitude at which the amplitude in the nonlinear resonance mode of the angular velocity sensor is rapidly increased. Comparing the jump frequency of the first jump frequency with the second jump frequency at which the amplitude decreases sharply. If the second jump frequency is higher than the first jump frequency, the initial drive frequency is set to a value less than the first jump frequency; When the second jump frequency is lower than the first jump frequency, the initial drive frequency is set to a value higher than the first jump frequency, and after the drive amplitude is increased by oscillation, the first and second jump frequencies are set.
The frequency is set to a set frequency between the jump frequencies of the above, and the amplitude is adjusted so as to have a predetermined value in the frequency range.

According to a fourth aspect of the present invention, there is provided a driving method for driving the angular velocity sensor device according to the second aspect, wherein the frequency of the oscillating means is increased by a first increase in the amplitude of the angular velocity sensor in a nonlinear resonance mode. Comparing the jump frequency of the first jump frequency with the second jump frequency at which the amplitude decreases sharply. If the second jump frequency is higher than the first jump frequency, the initial drive frequency is set to a value less than the first jump frequency; When the second jump frequency is lower than the first jump frequency, the initial drive frequency is set to a value higher than the first jump frequency, and after the drive amplitude is increased by oscillation, the first and second jump frequencies are set.
The frequency is set to a set frequency between the jump frequencies of the above, and the frequency is adjusted so as to be a set value in the frequency range.

According to a fifth aspect of the present invention, there is provided an angular velocity sensor, a driving means for exciting a predetermined vibration to the angular velocity sensor, a driving amplitude detecting means for detecting a driving vibration amplitude of the angular velocity sensor, and the driving amplitude detecting means. An amplifier for amplifying a signal of an amplitude detected by the means, a filter for attenuating a peak of a resonance frequency other than a driving resonance vibration mode of the angular velocity sensor, and an angular velocity sensor by adjusting an amplitude of an input signal of the driving means. Drive amplitude control means for keeping the drive amplitude of the drive amplitude at a predetermined value, a phase shifter for shifting the phase of the output of the drive amplitude control means by a predetermined amount to an oscillating value,
Wherein the angular velocity sensor is driven by self-excited oscillation.

According to a sixth aspect of the present invention, there is provided an angular velocity sensor, a driving means for exciting a predetermined vibration to the angular velocity sensor, a driving amplitude detecting means for detecting a driving vibration amplitude of the angular velocity sensor, and the driving amplitude detecting means. An amplifier for amplifying a signal having an amplitude detected by the means, a filter for attenuating a peak of a resonance frequency other than a drive resonance vibration mode of the angular velocity sensor, and the angular velocity sensor by adjusting a frequency of an input signal of the driving means. Drive amplitude control means for keeping the drive amplitude of the drive amplitude at a predetermined value, and a phase shifter for shifting the phase of the output of the drive amplitude control means by a predetermined amount to an oscillating value, wherein the angular velocity sensor is self-excited oscillation. It is characterized by being driven.

According to the first to fourth aspects of the present invention, the resonance mode used for driving vibration of the angular velocity sensor has a non-linear characteristic due to the influence of large amplitude driving, and the vibration amplitude corresponding to the driving frequency cannot be uniquely determined. The operating point can be set stably to a larger amplitude than usual, and the amplitude can be controlled to a constant value by adjusting the amplitude or frequency of the input signal of separately excited oscillation Becomes possible.

According to the fifth and sixth aspects of the present invention, the angular velocity sensor is driven by self-excited oscillation. Therefore, even if a non-linear effect appears in the resonance characteristics due to the large amplitude driving, the driving can be stably performed with the large amplitude. Further, by adjusting the amplitude or frequency of the input signal before reaching the drive limit, the amplitude can be controlled to a constant value.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a block diagram of the angular velocity sensor device according to the first embodiment of the present invention. In FIG. 1, an angular velocity sensor 101 is a vibration type angular velocity sensor. The angular velocity sensor 101 may be a tuning fork using a piezoelectric body or a conventional type having a prismatic (cylindrical) shape, or may be a vibrating gyroscope using a micromachining microfabrication technique using quartz or silicon. Drive
The detection method is not particularly specified, and the conventional piezoelectric vibrating gyroscope uses piezoelectric drive / piezoelectric detection, while the micromachine gyro uses electrostatic, electromagnetic, piezoelectric, etc. as drive methods.・ There are piezoelectric and piezoresistors. In the present embodiment, any of these methods may be selected and is not limited to a specific method.
Next, the driving means 102 drives the angular velocity sensor 101, and the driving amplitude detecting means 103 detects the amplitude, and is determined according to the driving / detection method unique to the angular velocity sensor 101, respectively.

The angular velocity sensor device includes a driving amplitude comparing unit 104, a driving voltage adjusting unit 105, and an oscillating unit 10.
6, an amplifier 107 and a drive frequency setting means 108 are connected in a loop as shown in the figure. The drive frequency setting means 108 sets the oscillation frequency of the oscillation means 106 to an initial drive frequency f _d1 near the resonance frequency f ₀ of the angular velocity sensor 101 as described later, and then gradually changes the oscillation frequency to the set frequency f _d2 . The drive amplitude comparing means 104 is to compare the set value A ₂ the amplitude detected from the drive amplitude detector 103. The driving voltage adjusting means 105 controls the amplification factor of the amplifier 107 based on the comparison result, the drive amplitude obtained from the driving vibration detection unit 103 and adjusts to match the A _2. Here the amplitude A ₂ as a target in is determined based on the amplitude values to leap large amplitude driving during signal of the angular velocity sensor.

FIG. 1 shows only a block of a driving portion of the angular velocity sensor. In actuality, a circuit section for detecting the angular velocity from the angular velocity sensor 101 according to the type is provided. For example, in the case of a semiconductor vibrating micromachine gyro formed of a fixed electrode and a vibrating body, an angular velocity can be detected by a capacitance detection method.

According to the first embodiment, the angular velocity sensor can be separately excited and oscillated at a constant amplitude even when the angular velocity sensor is driven with a large amplitude and a non-linear characteristic appears in the driving vibration.

In general, in order to realize sufficient sensitivity with a vibrating gyroscope, it is necessary to devise a sensor configuration so that Coriolis force can be increased. Coriolis force F
_c is represented by the following equation, where m is the mass of the weight of the vibrating body, v is the driving speed of the weight, and Ω is the input angular velocity.

(Equation 1) Therefore, increasing the sensitivity is equivalent to increasing the mass m of the vibrating body or the driving speed v. However, since there is a limit to the size of the mass m in order to be compatible with miniaturization, the driving speed v must be increased. Not get. On the other hand, since the speed is obtained by the time derivative of the position, it is necessary to increase the product f × A of the drive frequency f and the drive amplitude A in order to increase the drive speed v when the vibrating body is repeatedly driven by a sine wave. Therefore, it is necessary to increase the drive amplitude A as much as possible.

In order to make the drive amplitude A as large as possible,
The resonance frequency in the vibration mode to be driven is used as the normal drive frequency. As a result, a change larger than the amplitude determined by the relationship between the applied force and the spring constant (the so-called Hook's law) by a factor of resonance Q factor is obtained. When the drive amplitude A is not so large, the resonance curve shows the characteristic as shown in FIG. That is, when the driving frequency is swept, the resonance frequency f _{0 at} which the maximum value A _max of the driving amplitude A is obtained is uniquely determined irrespective of the sweep direction (direction of increasing or decreasing the frequency). Therefore, by driving at this frequency f ₀ , a drive amplitude that is Q times larger than the amplitude determined by a more static relationship is obtained.

However, when the drive amplitude A is further increased, a non-linear characteristic appears in this resonance characteristic. For example, FIG. 2B shows the case of the characteristic of a hardened spring in which the restoring force of the spring increases when driving with a large amplitude, and FIG. 2C shows the characteristic of a softening spring in which the restoring force of the spring decreases. . When such a characteristic appears, a desired drive amplitude cannot be obtained only by determining the frequency as in the linear case of FIG. 2A.

Taking the case of the hardened spring of FIG. 2B as an example,
The reason will be described. If swept to increase gradually frequencies from lower, up to a frequency f ₂ amplitude along the resonance characteristics are observed. However the drive amplitude at the time of the second jump frequency f ₂ decreases rapidly from B ₁ to B _2, thereafter the amplitude characteristic as is obtained again. Conversely, if the sweep to decrease gradually from its frequency, but from B ₂ to B ₃ is obtained amplitude characteristics as hereafter soared in B ₃ to B ₄ is observed amplitude again characteristics as . This frequency f _{1 is referred} to as a first jump frequency f ₁ . That is, the first and second jump frequencies f
₁ ~f ₂ between the can take two kinds of amplitudes, so that the amplitude is determined by the sweep direction of the frequency. Therefore, depending on the sweep direction of the frequency generated may not be set to B ₁ from B ₄ that the amplitude becomes larger. on the other hand,
In the case of softening the spring of FIG. 2 (c), similarly to FIG. 2 (b), the first, between the second jump frequency f ₃ ~f ₄ corresponds to it, more amplitude depending sweep direction of the frequency also it will occur if the larger C ₄ can not be set to C _1.

The present embodiment provides a driving method capable of driving an angular velocity sensor with a driving amplitude as large as possible even if the resonance characteristics show nonlinear characteristics as described above. Hereinafter, for the sake of simplicity, the angular velocity sensor 101 is assumed to be a semiconductor vibration type micromachine gyro of an electrostatic drive capacitance detection method, and the vibrator is driven by applying an electrostatic force through electrodes formed at predetermined intervals. Shall be. That is, the driving unit 102 converts an AC signal corresponding to the driving force input to the driving electrode into a driving voltage that gives an appropriate electrostatic force. Actually, in order to obtain the driving force as large as possible, a DC voltage is superimposed on an input AC voltage to generate an electrostatic force. This is described in detail in, for example, Japanese Patent Application Laid-Open No. 9-196682 “Angular velocity sensor and acceleration sensor”.

On the other hand, it is assumed that the drive amplitude is detected by a change in capacitance of a capacitor formed by a fixed electrode and a vibrating body. That is, the drive amplitude detection means 103 is a fixed electrode in structure, forms a capacitor as a pair with a part of the vibrating body, and electrically converts a minute capacitance change into a voltage change of an AC voltage. It becomes a V converter. As a CV converter, for example, a paper (Silicon rate sensor) by Nakamura et al.
using anisotropic etching technology, Transduc
ers'93, p.642 to p.645), a J-FET having a high input impedance is used as a source follower by a self-bias method.

Next, the operation of this embodiment will be described with reference to the graph of FIG. 2 and the flowchart of FIG. First, when the operation is started, in the flowchart of FIG. 3, in step S1, an initial drive frequency f _d1 is set by the drive frequency setting means 108 and generated by the oscillation means 106. In this embodiment, the oscillating means 106 is configured using, for example, a voltage controlled oscillator (hereinafter, referred to as a VCO), the oscillating frequency can be adjusted by a control voltage, and a sine wave output voltage can be obtained.

However, the oscillation frequency f is controlled by the drive frequency setting means 108 as follows. First, when the resonance characteristic of the driving vibration mode is a hardened spring characteristic as shown in FIG. 2B, the initial initial driving frequency f _d1 is less than f _{1 at} which a jump phenomenon in which the amplitude sharply increases occurs. for example, set to a frequency between f ₁ and the resonance frequency f ₀ of the linear mode. The oscillating means 106 generates a driving AC signal at the oscillating frequency f _d1 , amplifies the signal to a predetermined value by the amplifier 107, and inputs the amplified signal to the driving means 102. The driving unit 102 drives the angular velocity sensor 101. The drive amplitude detector 103 detects the amplitude A _d at that time.

When the angular velocity sensor 101 is driven at a frequency f _d1 near resonance, the amplitude grows to a predetermined amplitude determined by resonance characteristics. The time required for the amplitude to grow is determined by the following time constant τ.

(Equation 2) Here, f _d represents the drive frequency, ω _d represents the drive angular frequency, and Q represents the resonance Q value. That is, for example, Q = 20,000, f
_{When d} = 10 kHz, the time constant τ is 0.64 seconds.
If a time sufficiently larger than this time constant elapses, the amplitude has grown to a desired value. Whether or not the amplitude has grown sufficiently may be determined directly by the magnitude of the amplitude, or may be determined by comparing the elapsed time after activation with the time constant τ. Here, it is checked whether the amplitude value A _d obtained this time at step S3 exceeds the target value A _1. If this level is exceeded, steps S4 and S
The loop 5 is repeated, and the initial drive frequency is gradually increased from f _d1 to set the set frequency f _d2 between the _two jump frequencies f ₁ and f ₂ . This is performed by changing the control voltage of the VCO, which is the oscillating means 106, by the drive frequency setting means 108. Thus, the drive amplitude is to be set to a value between B ₄ of B _1. In this case, the angular velocity sensor can be driven with a large amplitude.

In order to increase the sensitivity of the angular velocity sensor device, it is necessary to increase the drive amplitude and control the drive amplitude to be constant. The large amplitude drive can be achieved by the above-described method, and the constant amplitude is realized by the following feedback control. That the driving amplitude detection means 103 drive amplitude detected by the A _d and the driving amplitude comparison means 104 in step S6~S8 compared with desired values A _2, lowering the gain of the amplifier 107 in the driving voltage adjusting means 105 is larger (step S7) If it is smaller, the amplitude can be controlled to be constant by adjusting the gain of the amplifier 107 in the direction of increasing (step S8). The target value A ₂ of the drive amplitude is set to be smaller than the limit amplitude B ₁ of jumping phenomenon occurs.

On the contrary, the resonance characteristic of the driving vibration mode is shown in FIG.
In the case of the softening spring characteristic as shown in (c), the first driving frequency f _d1 has a first jumping phenomenon in which the amplitude jumps in a direction in which the amplitude sharply increases.
Is set to a frequency higher than the jump frequency f ₃ , for example, a frequency between f ₃ and the resonance frequency f _{0 in the} linear mode. Then, after the growth of oscillation, the drive frequency may be gradually lowered from f _d1 and set to f _d2 between the two jump frequencies f ₃ and f ₄ . The drive amplitude control means may be the same.

As described above, even when driving is performed with a large amplitude so that nonlinearity occurs in the driving vibration, separately excited oscillation can be performed with a constant amplitude. Note that these signal processing circuits are
An analog circuit such as a multiplier may be used, or a microcomputer may be introduced and a digital control system based on a program may be used.

(Second Embodiment) Next, a second embodiment of the present invention will be described.
An embodiment will be described with reference to the drawings. FIG. 4 is a block diagram showing an angular velocity sensor device according to a second embodiment of the present invention. In FIG. 4, an angular velocity sensor 401 is a vibration type angular velocity sensor. Drive means 40
2. The drive amplitude detecting means 403 includes an angular velocity sensor 401
The means is determined according to the specific drive / detection method. The angular velocity sensor device includes a driving amplitude comparing unit 404, a driving frequency adjusting unit 405, an oscillating unit 406, and an amplifier 40.
7, a drive frequency setting means 408 is provided. The oscillating means 406, the amplifier 407, the driving means 402, the angular velocity sensor 401, the driving amplitude detecting means 403 and the driving amplitude comparing means 404 are the same as the corresponding blocks in the first embodiment.

According to the second embodiment, when the angular velocity sensor is driven with a large amplitude, the angular velocity sensor is separately excited by adjusting the frequency of the input signal of the external oscillation circuit even if the driving vibration has a non-linear characteristic. Can be done.

In this embodiment, only the means for adjusting the drive amplitude of the angular velocity sensor is different from that of the first embodiment. That is, the drive frequency adjusting means 405 indirectly adjusts the amplitude by directly changing the frequency of the oscillation means 406. The other blocks are the same as the corresponding names of the blocks shown in FIG. Therefore,
The large-amplitude drive is the same as in the first embodiment, and a description thereof will be omitted.

Next, the operation of this embodiment will be described with reference to the flowchart of FIG. In the flowchart of FIG. 5, the operations in steps S1 to S5 are the same as those shown in FIG. Now, after the drive frequency becomes f _d2 , the drive amplitude is controlled to a constant value. As a method of controlling the drive amplitude to a constant value, there is a method of directly controlling the amplitude of the separately excited oscillation AC signal input to the angular velocity sensor described in the first embodiment. The frequency of the oscillation AC signal is adjusted and indirectly controlled. For example,
While driving amplitude A ₂ to be set in the case of FIG. 2 showing the properties of the cured spring (b) is to be between B ₄ .about.B _1, relationship between the frequency and drive amplitude is related soaring in this section Therefore, the amplitude is controlled by comparing the drive amplitude detected by the drive amplitude detection means 403 with a desired value A ₂ by the drive amplitude comparison means 404.
This is performed by lowering the oscillation frequency of 06 (step S12) and, if smaller, adjusting the oscillation frequency of the oscillation means 406 to increase (step S11). Conversely, in the case of a softening spring having a characteristic as shown in FIG. 2C, the relationship between the frequency and the drive amplitude in the sections C _{1 to} C ₄ is a rightward downward relationship. Oscillator 406
May be reversed in the case of the hardening spring.

As described above, even when driving is performed with a large amplitude so that the driving vibration becomes non-linear, separately excited oscillation can be performed with a constant amplitude. Note that these signal processing circuits are
An analog circuit such as a multiplier may be used, or a microcomputer may be introduced and a digital control system based on a program may be used.

(Third Embodiment) FIG. 6 is a block diagram of an angular velocity sensor device according to a third embodiment of the present invention. In the present embodiment, the angular velocity sensor device is driven by forming a single loop and performing self-excited oscillation instead of separately excited oscillation in which an AC voltage is applied to drive the device. 6, an angular velocity sensor 601 is a vibration type angular velocity sensor. A tuning fork using a piezoelectric body or a conventional type having a prismatic or cylindrical shape may be used, or a vibrating gyroscope using micromachining microfabrication technology using quartz or silicon may be used. The drive and detection method is not particularly specified, and the conventional piezoelectric vibrating gyroscope is piezoelectric drive / piezoelectric detection, and the micromachine gyro is driven by electrostatic, electromagnetic, piezoelectric, etc., and the detection method is static. There are capacitance, piezoelectric, and piezoresistors. In the embodiment of the present invention, any of these methods may be selected and is not limited to a specific method. Next, the drive means 602 and the drive amplitude detection means 603 are also determined according to the drive / detection method unique to the angular velocity sensor 601. The angular velocity sensor device includes an amplifier 604, a filter 605, and an automatic gain adjusting means (hereinafter, referred to as an automatic gain adjusting means).
AGC 606, a phase shifter 607, and an attenuator 608.

In the case of forming a single loop in this way, oscillation occurs when the Barkhausen oscillation condition (loop gain is 1 and phase change in a single loop is an integral multiple of 360 °) is satisfied. In FIG. 6, it is assumed that a single loop is formed to excite self-excited oscillation as shown in FIG.
Note that the angular velocity sensor 601, the driving unit 602, and the driving amplitude detecting unit 603 are the same as those in the above-described first and second embodiments. The phase shifter 607 changes the phase of the input signal so that the phase condition under the oscillation condition matches.

Since the angular velocity sensor 601 is of a vibration type, it has at least two resonance modes corresponding to a driving vibration mode and a detection vibration mode in terms of frequency characteristics.
In self-excited oscillation, in order to oscillate in a desired drive resonance mode in conformity with the Barkhausen oscillation conditions, first, a resonance peak other than the drive oscillation mode is relatively suppressed by the filter 605. The characteristics of the filter 605 may be appropriately selected according to frequency characteristics such as a high-pass filter or a band-pass filter. The loop gain at the resonance peak of the driving vibration in the single loop is adjusted to a level slightly larger than 1 by the amplifier 604 and the attenuator 608. The phase change at the resonance peak is also adjusted to almost 0 ° by the phase shifter 607. In the initial stage of the self-sustained pulsation, the drive amplitude control means (hereinafter simply referred to as AGC) 606 may directly connect the input and output.
With this setting, it becomes possible to excite oscillation in a desired drive resonance mode.

In the initial stage of the self-sustained pulsation, linear resonance is excited as shown in FIG. 2A, but as the drive amplitude increases, the nonlinearity as shown in FIG. Often occurs. In the case of self-excited oscillation, unlike the separately excited oscillation, the oscillation grows with the maximum amplitude according to the state of the driving amplitude. There is no need to change the frequency appropriately according to the amplitude. However, if the drive amplitude increases by a certain value or more, the drive limit may be exceeded, that is, the amplitude may suddenly decrease beyond the amplitude B ₁ or C ₁ and enter an unstable state in which the drive resonance grows again. If control is not performed, the circuit configuration will not be practical.

In this embodiment, the configuration of the AGC 606 is as shown in FIG. In FIG. 7, reference numerals 701 and 706 denote first and second reference voltage generating means, respectively. The rectifier 702 calculates the amplitude of the input signal. Reference numeral 703 denotes a drive amplitude calculation unit that uses outputs of the reference voltage generation unit 701 and the rectification unit 702 to calculate
Calculate the amplitude of the new drive AC signal. A PLL (phase locked loop) 704 outputs a sine wave output having the same oscillation frequency synchronized with the input signal and having a constant amplitude. The multiplier 705 multiplies the output of the PLL 704 and the output of the drive amplitude calculation means 703 to generate a new drive AC signal. The selector 707 compares the voltage level rectified by the rectifier 702 with the reference voltage from the reference voltage generator 706, and outputs an input signal directly in the initial state of self-excited oscillation in which the reference voltage is higher. When the amplitude becomes larger than the value determined by the reference voltage generator 706, the output is switched to the output of the multiplier 705. The output of the selector 707 is provided to the drive amplitude calculation means 703 via the rectification means 708. The drive amplitude calculator 703 is a rectifier 7 that rectifies the output of the selector 707.
Calculates a driving amplitude based on 08 means V _ref1 output V _in and the reference voltage generating means 701 outputs V _out and the rectifier unit 702, and outputs to the multiplier 705.

There are various methods for calculating the drive amplitude in the drive amplitude calculating means 703 for controlling the drive amplitude to a constant value. For example, the reference voltage generating means 70
The reference voltage determined by 1 is V _ref1 , and the drive amplitude calculating means 703
The input voltage amplitude may be V _in , the output voltage amplitude may be V _out , and k may be a constant (0 <k <1).

(Equation 3) In addition, as shown in the following equation (4), it is configured by multiplication / division and indirectly V _ref1 =
V _in may be realized.

(Equation 4) In any case, this configuration makes it possible to keep the drive amplitude at a constant value.

As described above, the amplitude automatically increases after the start of the oscillation, and even if the driving is performed with a large amplitude so that the driving vibration becomes non-linear,
Self-excited oscillation of the angular velocity sensor at a constant amplitude becomes possible. These signal processing circuits may be constituted by analog circuits such as OP amplifiers and multipliers, or may be constituted by introducing a microcomputer to constitute a digital control system by a program.

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described.
A driving method of the angular velocity sensor device according to the embodiment will be described. The basic configuration is the same as the block diagram of FIG. 6 used in the third embodiment, but the control mode of the drive amplitude is different.

In the present embodiment, the configuration of AGC 606 is as shown in FIG. In FIG. 8, reference numerals 801 and 806 denote first and second reference voltage generating means, respectively. The rectifier 802 calculates the amplitude of the input signal. The drive frequency calculation means 803 calculates the frequency of a new drive AC signal using the outputs of the reference voltage generation means 801 and the rectification means 802. VCO8
Reference numeral 04 denotes a sine wave having a constant amplitude at the frequency determined by the drive frequency calculation circuit 803. Multiplier 805
Multiplies the output of the rectifier 802 by the VCO 804,
This is to generate a new drive AC signal. Finally, the selector 807 compares the output of the rectifier 802 with the output of the reference voltage generator 806. If the rectified output is equal to or lower than the reference voltage, the selector 807 directly outputs the input signal in the initial state of the self-excited oscillation. Is larger than the value determined by the reference voltage generator 806, the output is switched to the output of the multiplier 805.

The frequency calculating means in the driving frequency calculating means 803 is as follows. First, when a resonance characteristic of the time of large amplitude has a hardened spring characteristics as shown in FIG. 2 (b), the section B ₄ .about.B ₁ since the relationship between the frequency and drive amplitude is related soaring The control of the amplitude is performed by comparing the drive amplitude detected by the rectifier 802 with a reference value _Vref1 corresponding to the target amplitude set by the reference voltage setting means 801.
An output voltage is applied to the VCO 804 such that the oscillation frequency is decreased when the oscillation frequency is higher, and the oscillation frequency is increased when the oscillation frequency is lower. Conversely, since the relationship between the frequency and drive amplitude is a relationship of downward-sloping in the section C ₁ -C ₄ in the case of softening the spring showing the characteristics as in FIG. 2 (c), a method of adjusting the oscillation frequency What is necessary is just to reverse the case of a hardening spring. In any case, this configuration automatically raises the amplitude after the start of oscillation, and the self-excited oscillation can be performed at a constant amplitude even when a large amplitude is driven so that the drive amplitude becomes non-linear. It is possible to keep the value.

As described above, even when driving is performed with a large amplitude so that the driving vibration becomes non-linear, self-excited oscillation can be performed with a constant amplitude. Note that these signal processing circuits are
An analog circuit such as a multiplier may be used, or a digital control system based on a program by introducing a microcomputer may be used.

[0048]

As described above, according to the present invention, when a vibration type angular velocity sensor is driven with a large amplitude utilizing resonance characteristics, even if nonlinear characteristics appear in the resonance characteristics, a constant amplitude can be obtained by independent excitation and self-excited oscillation. Can be driven. Therefore, the Coriolis force can be made sufficiently large, and as a result, the vibration type angular velocity sensor can be made smaller and more sensitive. Therefore, the practical effect is great.

[Brief description of the drawings]

FIG. 1 is a block diagram of an angular velocity sensor device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a resonance characteristic of the angular velocity sensor.

FIG. 3 is a flowchart illustrating a processing procedure of a driving method of the angular velocity sensor device according to the first embodiment of the present invention.

FIG. 4 is a block diagram of an angular velocity sensor device according to a second embodiment of the present invention.

FIG. 5 is a flowchart illustrating a processing procedure of a driving method of the angular velocity sensor device according to the second embodiment of the present invention.

FIG. 6 is a block diagram of an angular velocity sensor device according to third and fourth embodiments of the present invention.

FIG. 7 is a block diagram showing an AGC circuit of an angular velocity sensor device according to a third embodiment of the present invention.

FIG. 8 is a block diagram illustrating an AGC circuit of an angular velocity sensor device according to a fourth embodiment of the present invention.

FIG. 9 is a schematic configuration diagram of a vibrating body of a conventional tuning fork type vibrating gyroscope.

[Explanation of symbols]

 101, 401, 601 Angular velocity sensor 102, 402, 602 Driving means 103, 403, 603 Driving amplitude detecting means 104, 404 Driving amplitude comparing means 105 Driving voltage adjusting means 405 Driving frequency adjusting means 106, 406 Oscillating means 107, 407, 604 Amplifier 108, 408 Driving frequency setting means 605 Filter 606 AGC 607 Phase shifter 608 Attenuator 701, 801 Reference voltage generating means 706, 806 Reference voltage generating means 702, 708, 802 Rectifying means 703 Driving amplitude calculating means 803 Driving frequency calculating means 704 PLL 804 VCO 705, 805 Multiplier 707, 807 Selector

Claims (6)

[Claims] An angular velocity sensor; an oscillating means; a first jump frequency at which the amplitude in the nonlinear resonance mode of the angular velocity sensor sharply increases is compared with a second jump frequency at which the amplitude sharply decreases, and the second jump frequency Is larger than the first jump frequency, the initial drive frequency is set to a value less than the first jump frequency, and the second jump frequency is set to the first jump frequency.
If the initial drive frequency is lower than the jump frequency of
Drive frequency setting means for setting the frequency to a value greater than the jump frequency of the first frequency and setting the frequency to a frequency set between the first and second jump frequencies after the drive amplitude is increased by oscillation; and amplifying the output of the oscillation means. An amplifier; a driving unit that excites a predetermined vibration to the angular velocity sensor based on an output of the amplifier; a driving amplitude detecting unit that detects a driving vibration amplitude of the angular velocity sensor; and an amplitude obtained by the driving amplitude detecting unit. An angular velocity sensor device, comprising: a drive amplitude comparison unit that compares the drive amplitude with a predetermined value; and a drive voltage adjustment unit that adjusts an amplification factor of the amplifier according to a result of the drive amplitude comparison unit. 2. The angular velocity sensor, the oscillating means, and the frequency of the oscillating means are compared with a first jump frequency at which the amplitude in the nonlinear resonance mode of the angular velocity sensor sharply increases and a second jump frequency at which the amplitude sharply decreases. When the second jump frequency is higher than the first jump frequency, the initial drive frequency is set to a value lower than the first jump frequency, and when the second jump frequency is lower than the first jump frequency. The initial drive frequency is set to a value higher than the first jump frequency, and the first drive frequency is increased after the drive amplitude is increased by oscillation.
Drive frequency setting means for setting a frequency to a set frequency between the first and second jump frequencies; an amplifier for amplifying an output of the oscillating means; and exciting a predetermined vibration to the angular velocity sensor based on an output of the amplifier. Driving means, driving amplitude detecting means for detecting a driving vibration amplitude of the angular velocity sensor, driving amplitude comparing means for comparing the amplitude obtained by the driving amplitude detecting means with a predetermined value, and a result of the driving amplitude comparing means. An angular velocity sensor device, comprising: a driving frequency adjusting unit that adjusts an oscillation frequency of the oscillating unit in response. 3. The driving method for driving an angular velocity sensor device according to claim 1, wherein the frequency of the oscillating means is reduced by a first jump frequency at which the amplitude in the nonlinear resonance mode of the angular velocity sensor is rapidly increased and the amplitude is rapidly reduced. The second jump frequency is compared with the first jump frequency. If the second jump frequency is higher than the first jump frequency, the initial drive frequency is set to a value less than the first jump frequency, and the second jump frequency is If the first jump frequency is lower than the first jump frequency, the initial drive frequency is set to a value higher than the first jump frequency.
A frequency set to a set frequency between the first and second jump frequencies, and adjusting the amplitude to be a predetermined value in the frequency range. 4. The driving method for driving an angular velocity sensor device according to claim 2, wherein the frequency of the oscillating means is decreased by a first jump frequency at which the amplitude of the angular velocity sensor in the nonlinear resonance mode is rapidly increased and the amplitude is rapidly decreased. The second jump frequency is compared with the first jump frequency. If the second jump frequency is higher than the first jump frequency, the initial drive frequency is set to a value less than the first jump frequency, and the second jump frequency is If the first jump frequency is lower than the first jump frequency, the initial drive frequency is set to a value higher than the first jump frequency.
And setting the frequency to a set frequency between the second jump frequency and the second jump frequency, and adjusting the frequency so as to be a set value in the frequency range. 5. An angular velocity sensor, a driving unit for exciting a predetermined vibration to the angular velocity sensor, a driving amplitude detecting unit for detecting a driving vibration amplitude of the angular velocity sensor, and a driving amplitude detecting unit for detecting an amplitude detected by the driving amplitude detecting unit. An amplifier for amplifying a signal; a filter for attenuating a peak of a resonance frequency other than a driving resonance vibration mode of the angular velocity sensor; and a driving amplitude of the angular velocity sensor being adjusted to a predetermined value by adjusting an amplitude of an input signal of the driving means. And a phase shifter that shifts the phase of the output of the drive amplitude control means by a predetermined amount to a oscillatable value, wherein the angular velocity sensor is driven by self-excited oscillation. Angular velocity sensor device. 6. An angular velocity sensor, a driving unit for exciting a predetermined vibration to the angular velocity sensor, a driving amplitude detecting unit for detecting a driving vibration amplitude of the angular velocity sensor, and a driving amplitude detecting unit for detecting the amplitude detected by the driving amplitude detecting unit. An amplifier for amplifying a signal; a filter for attenuating a peak of a resonance frequency other than a driving resonance vibration mode of the angular velocity sensor; and a driving amplitude of the angular velocity sensor being adjusted to a predetermined value by adjusting a frequency of an input signal of the driving means. And a phase shifter that shifts the phase of the output of the drive amplitude control means by a predetermined amount to a oscillatable value, wherein the angular velocity sensor is driven by self-excited oscillation. Angular velocity sensor device.