JPH0613970B2 - Angular velocity sensor - Google Patents

Description

TECHNICAL FIELD The present invention relates to an angular velocity sensor that can be suitably used for measurement and direction / orientation control of a moving body such as a vehicle, a ship, an aircraft, a robot, etc. In addition to the detecting means, auxiliary means is provided so that the phase difference angle formed by the vector of the output voltage due to the angular velocity and the vector of the null output voltage at rest is 90 degrees, and the angular velocity is calculated from the phase change of the combined vector of the respective voltages. The present invention relates to an angular velocity sensor configured to detect.

(Prior Art) FIG. 11 (a) is a diagram showing an example of a vibrating angular velocity sensor, and FIG. 11 (b) is a diagram showing a vibration mode of the angular velocity sensor.

As one of the vibrating angular velocity sensors, a square bar-shaped sound piece 1 is vibrated in a plane vertical direction (fx direction).
When is rotated at a certain angular velocity (Ω) in the axial direction, the Coriolis force causes vibration in the direction perpendicular to the drive surface (fy direction). Therefore, the amplitude of this vibration is proportional to the angular velocity. There is a sensor designed to detect the value of.

(Problems to be Solved by the Invention) In such a conventional vibration-type angular velocity sensor, the presence of a sensor output (null output voltage) at rest has a bad influence on the performance. It was desired to keep it.

However, it is very difficult to completely remove this null output voltage because it is generated due to an imbalance in the structure of the vibrator.

An object of the present invention is to provide an angular velocity sensor capable of accurately detecting an angular velocity from a phase change of an output signal by utilizing the null output voltage as described above, instead of removing the null output voltage.

(Means for Solving Problems) The first configuration of the angular velocity sensor according to the present invention is generated in the Y-axis direction when the vibrator is excited in the X-axis direction by the driving means and rotated about the Z-axis. In the angular velocity sensor for detecting the angular velocity by detecting the vibration due to the Coriolis force, the phase difference angle between the vector of the output voltage depending on the angular velocity of the vibrator rotating and the vector of the null output voltage at rest is 90. Auxiliary drive means arranged on the detection side surface of the vibrator so that a drive signal is applied thereto, and phase detection means for detecting an angular velocity from the phase difference between the combined vector of the output voltage and the null output voltage. Is provided.

In the second configuration of the angular velocity sensor according to the present invention, when the vibrator is excited in the X-axis direction by the driving unit and rotated about the Z-axis, the vibration due to the Coriolis force generated in the Y-axis direction is detected by the detecting unit. Then, in the angular velocity sensor for detecting the angular velocity, in the oscillator, the phase difference angle formed by the vector of the output voltage depending on the angular velocity of the vibrator during rotation and the vector of the null output voltage at rest is 90 degrees. Auxiliary detection means arranged on the driving side surface to which the detection output signal is added, and phase detection means for detecting the angular velocity from the phase difference of the combined vector of the output voltage and the null output voltage are provided.

In each of the above-mentioned configurations, the vibrator can be applied to a tuning piece shape or a tuning fork shape.

(Examples) Hereinafter, the present invention will be described in detail with reference to the drawings and the like.

FIG. 1 is a perspective view showing a first embodiment of an angular velocity sensor according to the present invention, FIG. 2 is a circuit diagram showing an equivalent circuit of the same embodiment sensor, and FIG. 4 is a view of the same embodiment sensor. FIG. 4 is a circuit diagram showing an equivalent circuit, FIG. 4 is a diagram showing a phase relationship of output signals of the sensor of the same embodiment, FIG. 5 is a vector diagram of output signals of the sensor of the same embodiment, and FIG. It is a figure showing the relation of the null output voltage of an example sensor, sensitivity, and linearity.

In FIG. 1, 10 is a vibrator, 21 to 25 are piezoelectric elements, and 31 and 32 are support wires.

In the first embodiment, an example of the sound piece type vibrator 10 is shown, and the cross section of the vibrator 10 is a substantially square shape in which the ratio of the vertical and horizontal sides is close to 1. Has been.

As a material of the vibrator 10, a metal or a non-metal having a good elastic property is used. As an example, for example, Ni-
Examples include constant-elastic alloys such as SPAN-C and Elinvar, quartz, ceramics, and the like. In addition, piezoelectric material, crystal, PZ
Crystals such as T and LiTaO ₃ and ceramics
May be In this case, electrodes can be directly provided on the vibrator 10 to perform drive detection.

The vibrator 10 is supported by parallel support lines 31 and 32.

The vibrator 10 includes piezoelectric elements 21 to 21 for driving or detecting.
25 is attached by adhesion or vapor deposition. A piezoelectric element 21 for driving is provided on the first surface 11 of the vibrator 10, a piezoelectric element 22 for detection is provided on the second surface 12, a piezoelectric element 23 for drive feedback is provided on the third surface 13, and A piezoelectric element 24 for braking is arranged on the surface 14. Furthermore, on the first surface 11,
A piezoelectric element 25 for auxiliary driving on the detection side is arranged.

As a material of these piezoelectric elements 21 to 25, PZT, ZnO or the like having a large electromechanical coupling coefficient is used.

As shown in FIG. 2, the control circuit of the vibrator 10 is
By combining the driving piezoelectric element 21 and the feedback piezoelectric element 23 to form a self-excited vibration circuit, and connecting the driving side drive signal to the detection side auxiliary piezoelectric element 25, a minute and stable null output at rest Connected to generate a voltage. And the arrangement of the auxiliary piezoelectric element drive electrode is 90 °
The difference results in signals that are essentially 90 ° out of phase. The phase detection circuit 42 detects the phase difference between the detection signal and the drive signal, and the amplification circuit 43 amplifies the value to output the angular velocity.

That is, the vibrator 10 is self-excited in the fx direction,
When rotated in the Z-axis direction, vibration occurs in the fy direction.
The vibration mode at this time is the primary mode (similar to FIG. 11 (b)). The phase difference between the signal detected at this time and the drive signal is measured and amplified to obtain an angular velocity output.

Note that a drive feedback signal can be used instead of the drive signal to detect the phase difference in the phase detection circuit 42.
Further, in FIG. 2 and FIG. 8 to be described later, the auxiliary piezoelectric elements are represented side by side for convenience.

Next, the principle of detecting the angular velocity by the phase difference of the present invention will be further described with reference to FIGS.

FIG. 3 is a diagram showing an equivalent circuit in the case of the sound piece type angular velocity sensor shown in FIG.

In FIG. 3 (a), V ₁ is a drive signal input, V ₂ is a detection signal output, Cd ₁ and Cd ₂ are input / output capacitors, A ₁ x and A ₂ y are force coefficients, and ΔA ₁ y is an auxiliary drive. Force coefficient, ωd is a driving angular frequency, ω ₀ x and ω ₀ y are resonant angular frequencies, and Zx and Zy are impedances. Note that FIG. 3 (b)
Shows the equivalent circuit when Ω ₀ = 0 in the above case.

The phase relationship of the output signals in such a case is generally expressed as shown in FIG. That is, the output signal V ₂ is generated by the vibrator 1
Is the vector sum of the component V _Ω generated by the rotation of V and the quiescent voltage (null output voltage) V _N. If the component V _Ω generated by rotation is proportional to the applied angular velocity and the null output voltage V _N is unchanged, Δθ = θ ₂ from the phase difference between the detection signal output V ₂ and the null output voltage V _N. The angular velocity can be detected by the relationship of −θ _N.

In FIG. 4, looking at the symmetry of the magnitude of the detection signal output V ₂ when the component V _Ω generated by rotation is positive (for example, clockwise rotation) and negative (for example, counterclockwise rotation). , Θ _N ≠ 90 °, it can be seen that they are asymmetric.

Therefore, the component V _Ω generated by the rotation and the null output voltage V
_If the relationship of _N is set so as to have a phase difference of 90 degrees as shown in FIG. 5, since Δθ changes symmetrically with respect to ± V _Ω , accurate measurement can be performed. .

When the null output voltage V _N = 0, the phase difference between the detection signal output V ₂ and the component V _Ω generated by rotation becomes zero, and | V ₂ | and Ω ₀ have a proportional relationship. It cannot be detected by phase difference. This fact became clear only after considering the equivalent circuit.

In the present invention, the piezoelectric element 21 normally required for drive detection is used.
2 to 24, the piezoelectric element 25 for auxiliary driving on the detection side shown in FIG. 1 is provided and connected as shown in FIG.
The null output voltage V _N is kept at a small and stable value, and the phase difference from V _Ω is 90 degrees. The magnitude of the null output voltage V _N is arbitrarily determined according to the characteristics, size, position, etc. of the piezoelectric element 25 for auxiliary driving on the detection side.

This fine adjustment of the phase is performed by adjusting the shape and size of the piezoelectric element, the installation location of the piezoelectric element, and the magnitude and phase of the drive signal, or a combination thereof.

As shown in FIG. 6, the sensitivity increases as the null output voltage V _N decreases. On the other hand, the linearity improves as the null output voltage V _N increases. Therefore, it may be set to an appropriate value according to the use of the angular velocity detection range.

FIG. 7 is a perspective view showing a second embodiment of the angular velocity sensor according to the present invention, and FIG. 8 is a circuit diagram showing a control circuit of the same embodiment sensor.

The parts having the same functions as those described in the first embodiment are designated by the same reference numerals.

In the second embodiment, as shown in FIG. 7, an auxiliary detection piezoelectric element 26 on the drive side is provided on the first surface 11, and the output of the piezoelectric element 26 is detected on the detection side as shown in FIG. It is intended to generate a minute and stable null voltage at rest by connecting to the piezoelectric element 22.

As shown in FIG. 8, the phase detector 42 detects the phase difference between the detection signal and the drive signal, and the amplification circuit 43 amplifies the value to obtain an angular velocity output. Note that the drive feedback signal may be used instead of the drive signal to detect the phase difference in the phase detection circuit 42, as described above.

FIG. 9 is a diagram showing a third embodiment of the angular velocity sensor according to the present invention, and FIG. 10 is a diagram showing a fourth embodiment of the angular velocity sensor according to the present invention.

The third and fourth embodiments are applied to tuning fork type vibrators, and correspond to the first and second embodiments of the tuning piece type, respectively.

A piezoelectric element 6 for driving is provided on each arm 51, 52 of the tuning fork 50.
1, 62 and piezoelectric elements 63, 64 for detection are arranged.

In the case of the third embodiment, the auxiliary piezoelectric element 65 is provided on the same surface as the piezoelectric element 64 for detection.

In the case of the fourth embodiment, the driving piezoelectric elements 61, 62
An auxiliary piezoelectric element 66 is provided on the same surface as.

The auxiliary piezoelectric elements 65 and 66 may be arranged near the tips of the tuning fork arms 51 and 52. In that case, arm 5
The force coefficient becomes smaller as it approaches the tip of 1,52, and becomes zero at the free end. Further, the change in the resonance frequency becomes larger due to the change in mass toward the tip. In addition, FIG. 9 (b) and 10
In FIG. (B), the auxiliary piezoelectric elements are shown displaced for convenience.

Various modifications can be made without being restricted to the embodiments described above.

The support of the vibrator is not limited to the support wire, but may be a thin rod, a frame, or the like.

Further, the number of the auxiliary piezoelectric elements 25 and 26 is not limited to one and may be two or more.

(Effects of the Invention) As described in detail above, according to the present invention, auxiliary means such as an auxiliary piezoelectric element is provided, and a null output voltage that is minute and stable and has a phase difference of 90 degrees with the drive voltage is provided. Since the angular velocity is generated and the angular velocity is detected from the phase of the vector sum of each output voltage, there is an effect that symmetrical and accurate measurement can be performed in the clockwise direction and the counterclockwise direction.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment of an angular velocity sensor according to the present invention, FIG. 2 is a circuit diagram showing a control circuit of the same embodiment sensor, and FIG. FIG. 4 is a circuit diagram showing an equivalent circuit, FIG. 4 is a diagram showing a phase relationship of output signals of the sensor of the same embodiment, FIG. 5 is a vector diagram of output signals of the sensor of the same embodiment, and FIG. It is a figure showing the relation of the null output voltage of an example sensor, sensitivity, and linearity. FIG. 7 is a perspective view showing a second embodiment of the angular velocity sensor according to the present invention, and FIG. 8 is a circuit diagram showing a control circuit of the same embodiment sensor. FIG. 9 is a diagram showing a third embodiment of the angular velocity sensor according to the present invention, and FIG. 10 is a diagram showing a fourth embodiment of the angular velocity sensor according to the present invention. FIG. 11 (a) is a diagram showing an example of a vibrating angular velocity sensor, and FIG. 11 (b) is a diagram showing vibration modes of the same angular velocity sensor. DESCRIPTION OF SYMBOLS 10 ... Oscillator 21-26 ... Piezoelectric element 31, 32 ... Support line 41 ... Drive circuit, 42 ... Phase detection circuit 43 ... Amplification circuit, 44 ... Braking circuit 50 ... Oscillator, 61-66 ... Piezoelectric element

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Sueaki Oshima 1-35-1 Izumihonmachi, Komae-shi, Tokyo Tokyo Tokio Keiki Co., Ltd.

Claims (2)

[Claims] 1. A vibrator is excited by a driving means in the X-axis direction,
In an angular velocity sensor for detecting an angular velocity by detecting a vibration due to Coriolis force generated in the Y-axis direction when rotating about the Z-axis, a vector of an output voltage depending on an angular velocity when the vibrator rotates Auxiliary driving means arranged on the detection side surface of the vibrator so that a drive signal is applied such that the phase difference angle formed by the vector of the null output voltage at rest is 90 degrees, the output voltage and the null output voltage 2. An angular velocity sensor, comprising: a phase detecting unit that detects an angular velocity from the phase difference of the combined vector of 1. 2. A vibrator is excited in the X-axis direction by drive means,
In an angular velocity sensor for detecting an angular velocity by detecting a vibration due to Coriolis force generated in the Y-axis direction when rotating about the Z-axis, a vector of an output voltage depending on an angular velocity when the vibrator rotates Auxiliary detection means arranged on the driving side surface of the vibrator for adding a detection output signal so that the phase difference angle formed by the vector of the null output voltage at rest is 90 degrees, the output voltage and the null output An angular velocity sensor, comprising: a phase detection unit that detects an angular velocity from the phase difference of a combined vector of voltages.