JPH08136262A - Vibration gyroscope - Google Patents

Abstract

PURPOSE: To achieve higher safety and reliability by simplifying a circuitry. CONSTITUTION: A bridge circuit Br comprising four bridge arms R1 , R2 , R3 and R4 and at least a pair of transducers 2 and 3 for driving and detection stuck on a vibrator 1 are interposed between bridging circuits Bc-Bb of the bridge circuit Br. A self excitation drive feedback loop Fk containing an amplification circuit Amp is formed between both input and output terminals Ba-Bb of the bridge circuit Br.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an aircraft, a ship, a vehicle,
The present invention relates to a vibration gyro device for measuring an angular velocity suitable for position / orientation control of a robot or the like, and particularly has a simple circuit configuration,
This relates to a vibration gyro device with improved stability and reliability of characteristics.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 4, a piezoelectric element 16a for driving and a piezoelectric element 16a for detecting are included in a sound piece type vibrator 12.
b, the feedback piezoelectric element 16c is attached, and the feedback output from the feedback piezoelectric element 16c is transmitted from the oscillation circuit 24 via the fixed resistors 26a (= R ₁ ) and 26b (= R ₂ ) to the piezoelectric element 16a. , 16b in addition to the self-excited drive, vibrator 1
The bending vibration caused by the Coriolis force generated in the y-axis direction when the angular vibration is generated around the z-axis is detected by the piezoelectric elements 16a and 16b, and the output is differentiated. A vibration gyro having a circuit configuration for measuring the rotational angular velocity Ω by adding it to the dynamic circuit 30 has been proposed (Japanese Patent Publication No. 6-3455, JP-A-5-32).
No. 2582).

[0003]

FIG. 5 shows an equivalent circuit of the circuit configuration of this vibrating gyro. Here, although the ground is not shown in FIG. 4, the ground is additionally shown in FIG. 5 from the viewpoint of common general technical knowledge. The equivalent impedances Z ₁ , Z ₂ and Z ₃ near the resonance point of the driving and detecting piezoelectric elements 16a and 16b and the feedback piezoelectric element 16c in FIG.
Shown in. Here, f _r is a series resonance point and f _a is a parallel resonance point.

In FIG. 5, the state in which the rotational angular velocity is not applied,
That is, when only self-excitation is performed, the equivalent impedances Z ₁ and Z ₂ of the driving and detecting piezoelectric elements 16a and 16b are Z ′ ₁ ≠ Z ′ ₂ at the self-excitation frequency f ₀ , that is, the piezoelectric elements have characteristic variations. Suppose. The state is shown in FIG. Fixed resistors R _1, when acceleration by adjusting the R ₂ a self-excited drive currents i _1, i ₂ in FIG. 5, the impedance Z _1,
The voltage drops e ₁ and e ₂ at the input point of Z ₂ can be easily set to e ₁ = e ₂ . Therefore, even if the characteristics of the piezoelectric element vary, the rotational angular velocity Ω can be measured without being affected by the characteristics of the piezoelectric element.

In this case, as is clear from the drawing, the fixed resistors R ₁ and R ₂ and the equivalent impedances Z ₁ and Z ₂ form a bridge circuit, and the differential circuit 30 serves as a bridge. Here, when the piezoelectric element changes with time and temperature, the equivalent impedances Z ₁ and Z ₂ become Z ₁ ± ΔZ ₁ and Z ₂ ± ΔZ _2.
As long as the same material is used, Z ₁ : ΔZ ₁ = Z ₂ : ΔZ ₂ , and the fixed resistors R ₁ and R ₂ are first adjusted to reduce the voltage drop e. _{If 1} = e ₂ , the bridge equilibrium condition is not broken. In this way, it is possible to obtain the effect that the rotational angular velocity Ω can be accurately measured without being affected by the characteristics of the piezoelectric element even if it changes over time or changes in temperature.

Next, in the state in which the rotational angular velocity is applied, as shown in FIG. 7, the gyro outputs e _{j1 and} e _j2 are equivalently applied as voltage sources, the equilibrium condition of the bridge is broken, and the detection outputs e _j1 and e. The potential difference of _j2 is equivalent impedance Z ₁ , Z ₂
Appears during the input of. By detecting this potential difference with the differential circuit 30, the rotational angular velocity Ω can be measured without being affected by the characteristics of the piezoelectric element even if the piezoelectric element has variations in characteristics, changes over time, or changes in temperature. It is a thing.

However, the detection output e ₁ + shown in FIG.
The stability of e _j1 and e ₂ + e _j2 is the self-excitation frequency f _0.
It depends on the stability of impedances Z ₁ and Z ₂ in (FIG. 6). Because the voltage drops e ₁ and e ₂ are the self-excitation frequency f
₀ Depending on the impedance Z _'1, Z' ₂ in (Fig. 6), the voltage drop e _1, e _2, since extremely large as compared with the detection output e _j1, e _j2, voltage drop e _1, e ₂ This is because the detection outputs e _j1 and e _j2 are hidden behind the change due to the fluctuation of. Generally, self-excitation is performed by adjusting the self-excitation frequency f ₀ to the parallel resonance point f _a of the impedance Z ₁ or Z ₂ . Is because, when the self-exciting the self-exciting frequency f ₀ in accordance with the series resonance point f _r, the fixed resistors R _1, the value impedance Z _'1, Z' ₂ as compared to the R ₂ becomes too small. Now, assuming that the assumed to be self-exciting the combined self-exciting frequency f ₀ in the parallel resonance point f _a of the impedance Z _1, the impedance Z _'1 be self-exciting frequency f ₀ is ± f ₀ change the impedance Z does not change much for a maximum point of _a characteristic curve, but the impedance Z _'2 are largely changed because a steep change point of the characteristic curve of the impedance Z _2. That is, the voltage drops e ₁ and e ₂ change due to changes in the impedances Z ′ ₁ and Z ′ ₂ , and the detection outputs e _j1 and e _j2 are hidden by the voltage drops e ₁ and e ₂ .

As described above, in the conventional vibrating gyroscope, even if the piezoelectric element has variations in characteristics, changes over time, and changes in temperature, the rotational angular velocity can be measured without being affected by the characteristics of the piezoelectric element. , With no rotational angular velocity applied,
That is, there is a problem in that stability and reliability are lacking due to the influence of the voltage drops e ₁ and e ₂ of the impedances Z ′ ₁ and Z ′ ₂ when only self-excitation is performed.

[0009]

[Object] The present invention has been made in view of the above difficulties, and an object thereof is to provide a vibrating gyro device having a simple circuit configuration and improved stability and reliability.

[0010]

In order to achieve this object, a vibrating gyro device of the present invention has a bridge circuit composed of four bridge arms, and at least a pair of driving members attached to a vibrator. -The detecting transducer is interposed in the bridge circuit of the bridge circuit. In this vibrating gyro device, a self-excited drive feedback loop including an amplifier circuit is formed between the input and output terminals of the bridge circuit.

Further, in this vibrating gyro device, a self-excited drive feedback loop is formed from the feedback transducer attached to the vibrator to the input side terminal of the bridge circuit via the amplifier circuit.

[0012]

In this vibrating gyro device, when the rotational angular velocity is not applied to the vibrator, that is, when only the self-excitation is performed,
As long as the balance condition of the four bridge arms of the bridge circuit is satisfied, the current flowing through the bridge circuit of the bridge circuit is 0.
Therefore, it is irrelevant to the equivalent impedance of the pair of driving / detecting transducers.

When a rotational angular velocity is applied to the vibrator, a current source for gyro detection output appears in the pair of driving / detecting transducers. The loop current of this current source is the sum of the current sources in the pair of driving / detecting transducers. This loop current is rectified. When a vibration is applied to the vibrator from the pair of transducers in the x-axis direction and an angular velocity is applied around the z-axis, the vibration caused by the Coriolis force generated in the y-axis direction is detected by the pair of transducers. The loop current allows the angular velocity to be measured. In this case, the detection output when the rotational angular velocity is applied is not affected by the voltage drop of the impedance in the driving / detecting transducer when the rotational angular velocity is not applied, that is, when only self-excitation is performed. Improves stability and reliability.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the vibrating gyro device of the present invention is applied to a sound piece type will be described below with reference to the drawings. Embodiment 1 As shown in FIG. 1, a vibrating gyro device of the present invention is a vibrating gyro device of the present invention, in which a pair of driving members are arranged on two adjacent surfaces of a vibrator 1 which is composed of a rectangular parallelepiped sound piece having a rectangular cross section. -Detection transducers 2 and 3 are attached. With this arrangement, the vibration direction of the vibrator 1 is set to the diagonal mode.

In consideration of temperature characteristics, the vibrator 1 is generally made of a metal such as Ni-SPAN-C or Erinba which has a constant elasticity. Also, as a special example, quartz, crystal,
It may be composed of an electrical insulator such as ceramic.
As the constant elastic electric insulator, Young's modulus has a small temperature coefficient and a small linear expansion coefficient, and glass is preferably used. In addition to the constant elasticity of glass, the mechanical Q is large and isotropic, and the glass has the necessary characteristics as a vibrator.

As the transducers 2 and 3, PZT is used.
Ceramic piezoelectric elements such as those based on ZnO, ZnO and BaTiO ₃ are used. In this vibrating gyro device, a bridge circuit B composed of _four bridge arms R ₁ , R ₂ , R ₃ and R ₄
r is formed. Both input and output side terminals Ba of the bridge circuit Br
A self-excited drive feedback loop Fk including a phase shift circuit Ps and an amplifier circuit Amp is formed between −Bb. Amplifier circuit Am
The output of p is applied to the bridge arms R ₁ and R ₂ from the input side terminal Ba of the bridge circuit Br via the resistor Ra, and the bridge arms R ₃ and R ₄ of the bridge circuit Br are output from the output side terminal Bb to the phase shift circuit Ps. Is applied to the amplifier circuit Amp via. The output terminal Bb of the bridge circuit Br is grounded via a resistor Rb.

Further, one side of the potential of the electrode of the transducer 2 and 3, dividing resistors R _0, R _'0 by the power supply voltage + B
Is maintained at a potential that is divided. The equivalent impedances Z ₁ and Z _{2 of} the pair of driving / detecting transducers 2 and 3 attached to the vibrator 1 are interposed in the bridge circuit Bc-Bb of the bridge circuit Br. A double-wave rectifier circuit Rec is connected to the bridge circuit Bc-Bb of the bridge circuit Br.

The values of the four bridge arms R ₁ , R ₂ , R ₃ and R ₄ of the bridge circuit Br are R ₁ / R when the rotational angular velocity is not applied to the vibrator 1, that is, when only the self-excitation is performed. It is set so that the equilibrium condition of ₂ = R ₃ / R ₄ is satisfied. Further, in FIG. 1, an amplifier circuit Amp, a phase shift circuit Ps, a bridge circuit B
The gain Re of the self-excited drive feedback loop Fk composed of r
(A) and the phase shift are respectively the amplification factor of the amplifier circuit Amp,
The phase shift amount Im (A) of the phase shift circuit Ps is adjusted to satisfy the self-oscillation condition of Re (A) ≧ 1 Im (A) = 0.

In the vibrating gyro device configured as described above, when the rotational angular velocity is not applied to the vibrator 1, that is, when only the self-excitation is performed, the four bridge arms R ₁ / R ₂ = R ₃ of the bridge circuit Br. As long as the balanced condition of / R ₄ is satisfied, the loop current flowing in the bridge circuit Bc-Bb of the bridge circuit Br is i ₀ = 0, and the equivalent impedances Z ₁ and Z of the pair of driving / detecting transducers 2 and 3 are It becomes irrelevant to ₂ .

When the rotational angular velocity is applied to the vibrator 1, as shown in FIG. 2, a current source of gyro detection outputs i _j1 and i _j2 appears in the pair of driving / detecting transducers 2 and 3. To do. Here, the impedances Z ₁ and Z ₂ are values when the self-excitation frequency is adjusted to the series resonance point _fr (FIG. 6) to perform the self-excitation. The loop current i ₀ = i _j1 + i _{j2 of} this current source, that is, the sum of the current sources in the pair of driving / detecting transducers 2 and 3. This loop current i ₀ is rectified by the double-wave rectification circuit Rec. In this way, when a vibration is applied to the vibrator 1 from the pair of transducers 2 and 3 in the x-axis direction and an angular velocity is received around the z-axis, the vibration caused by the Coriolis force generated in the y-axis direction is generated by the pair of transducers. The angular velocity Ω is measured by detecting from the transducers 2 and 3. In the vibrating gyro device according to the above-described embodiment, when there are variations in characteristics of the piezoelectric element, changes with time, and changes in temperature,
The rotational angular velocity cannot be measured without being affected by the characteristics of the piezoelectric element, but this point can be improved by selecting the material.

Embodiment 2 Further, as shown in FIG. 3, in the vibrating gyro device of the present invention, a pair of driving members are provided on three faces of a vibrator 1 which is composed of a rectangular parallelepiped sound piece having a triangular cross section in this example. -The detecting transducers 2 and 3 and the returning transducer 4 are attached. In this vibrating gyro device, a bridge circuit Br composed of _four bridge arms R ₁ , R ₂ , R ₃ and R ₄ is used.
Is formed. The output of the amplifier circuit Amp is a capacitor Ca
Is applied to the bridge arms R ₁ and R ₂ from the input side terminal Ba of the bridge circuit Br via the, and grounded from the bridge arms R ₃ and R ₄ .

From the feedback transducer 4 attached to the vibrator 1, the bridge circuit Br via the amplifier circuit Amp.
A self-excited drive feedback loop Fk is formed to reach the input side terminal Ba of. Further, the electric potentials on one side of the electrodes of the transducers 2 and 3 are maintained at the electric potential obtained by dividing the power source voltage + B by the voltage dividing resistors R ₀ and R ′ ₀ .

The equivalent impedance Z _{1 of} the pair of driving and detecting transducers 2 and 3 attached to the vibrator ₁ ,
Z ₂ is interposed in the bridge circuit Bc-Bb of the bridge circuit Br. Bridge circuit Bc-Bb of bridge circuit Br
A dual-wave rectification circuit Rec is connected to the. The four bridge arms R ₁ , R ₂ , R ₃ , R _{4 of} this bridge circuit Br
The value of is set so that the equilibrium condition of R ₁ / R ₂ = R ₃ / R ₄ is satisfied when the rotational angular velocity is not applied to the vibrator 1, that is, when only the self-excitation is performed.

In the vibrating gyro device configured as described above, when the rotational angular velocity is not applied to the vibrator 1, that is, when only the self-excitation is performed, the input side of the bridge circuit Br is fed from the feedback transducer 4 via the amplifier circuit Amp. Terminal B
The self-excited drive feedback loop Fk is easily formed by the path to a. When the rotational angular velocity is applied to the vibrator 1, as shown in FIG. 2, the vibrator gyro device operates similarly to the vibration gyro device of the first embodiment.

In these embodiments, the detection output in the state in which the rotational angular velocity is applied shows the influence of the voltage drop of the impedance in the driving / detecting transducer when the rotational angular velocity is not applied, that is, when only the self-excitation is performed. Since it is not affected, the stability and reliability of the gyro characteristics are improved. In the above embodiment, an example in which the vibrating gyro device is applied to a sound piece type using a triangular and quadrangular rectangular parallelepiped vibrator has been described. However, the vibrating gyro device of the present invention has an n-gonal cross section (n is 5). The above) can be applied to the polyhedron tone piece type, and the same can be applied to the case of applying to a tuning fork type.

[0026]

As is apparent from the above description, according to the vibrating gyro device of the present invention, the circuit configuration is simple and the stability and reliability of the gyro characteristic can be improved.

[Brief description of drawings]

FIG. 1 is a self-excitation circuit diagram of a vibration gyro device according to an embodiment of the present invention.

FIG. 2 is a detection circuit diagram of the vibration gyro device according to the present invention.

FIG. 3 is a self-excitation circuit diagram of a vibration gyro device according to another embodiment of the present invention.

FIG. 4 is a circuit diagram of a conventional vibrating gyro device.

FIG. 5 is a self-excitation circuit diagram of a conventional vibrating gyro device.

FIG. 6 is a graph showing characteristics of the vibration gyro device.

FIG. 7 is a detection circuit diagram of a conventional vibration gyro device.

[Explanation of symbols]

1 ... Oscillator 2, 3 ... A pair of driving / detecting transducers 4 ... Returning transducers R ₁ , R ₂ , R ₃ , R ₄ ... Bridge arm Br ... Bridge circuit Bc-Bb ... Bridging Circuit Ba-Bb …… Both input and output side terminals Amp …… Amplifier circuit Fk …… Self-excited drive feedback loop

Claims (3)

[Claims] 1. A bridge circuit composed of four bridge arms is formed, and at least a pair of driving / detecting transducers attached to a vibrator is interposed in a bridging circuit of the bridge circuit. Vibration gyro device. 2. The vibrating gyro device according to claim 1, wherein a self-excited drive feedback loop including an amplifier circuit is formed between both input and output terminals of the bridge circuit. 3. A self-excited drive feedback loop is formed from a feedback transducer attached to the vibrator to an input side terminal of the bridge circuit via an amplifier circuit. Vibration gyro device.