JPS6049216A - Angular velocity sensor - Google Patents

Abstract

PURPOSE:To reduce an offset and detect even a small angular velocity by fitting two piezoelectric elements to parallel oscillation surfaces of an oscillation body constituted so that Coriolis force is received, and mixing the output signals of the piezoelectric elements in in-phase relation. CONSTITUTION:An angular velocity sensor has a prism 1 as the oscillation body, and the prism 1 has the 1st surface, i.e. oscillation surface parallel to a surface containing X-X' and Y-Y' and the 2nd surface perpendicular to the 1st surface, i.e. oscillation surface parallel to a plane containing X-X' and Z-Z'. Then, the piezoelectric elements 2a, 2b, and 2c are fitted to the respective oscillation surfaces. The prism 1 is supported by supporting members 3a and 3b as nodal points of oscillation. This constitution reduces an offset and detects even a small angle.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] This invention relates to an angular velocity sensor that detects the angular velocity of a rotating body or the like.

[Prior art]

Lifting gyros that detect angular velocity using the Coriolis force have been proposed for various glazes. This is done by vibrating a prism 1 as shown in Fig. 1 in the z-z' force direction, for example, and
When a rotational force is applied around the 'direction 1, a vibration component in the Y-Y' force direction appears in the prism 1, and the amplitude in the Y-Y' force direction is fully proportional to the angular velocity around the x-x' axis. For this reason, Y
-Y' If the force direction vibration 1h is converted into an electric signal by an element force, a signal with an angular velocity of 1h can be obtained.

However, such conventional sensors are limited to pressure 'Jj.

Since the amplitude of the signal obtained from the element is small and the area of each surface in the longitudinal direction of the amada prism 1 is approximately the same, the vibration modes are similar, so when the angular velocity around the x-x' axis is not given. However, an offset phenomenon occurs in which the Y-Y' force direction vibration component appears slightly.

In order to reduce this offset, it is possible to change the plane tI'j ratio of the horizontal plane and the vertical IG plane among the longitudinal planes, but if you do this, the area of force 11 will be small, and the piezoelectric element will Since the area is small, the size of the output signal is also small.

[Objectives of the Invention and (τ·7) Therefore, the object of the present invention is to provide an angular velocity sensor that can reduce the offset without reducing the stiffness of the output.

In order to achieve this purpose, piezoelectric elements are installed on both sides of the vibrating surface, and the respective pressures R,! The present invention will be explained below using figures showing examples.

〔Example〕

FIG. 2 shows an embodiment of the vibrating body used in the present invention.
4, which is the parent diagram, the prism 1 which is the vibrating body has a vibrating plane parallel to the tenth direction, that is, the plane containing x-x' and y-y', and an i 'ii', that is, a plane including X-X' and z-z', has a flat vibration surface, and each vibration surface has a piezoelectric element 2a + 2
b + 2c, 2d are attached. and,
The square column 1 is supported by support members 3a and 3b at its nodal point, which becomes the point of vibration. The square column 1 is made of a conductive material.

3h is a circuit diagram of this invention, in which 4a and 4b are resistors, and 5 is a signal that inverts the phase of the output signal of the piezoelectric element 2d and combines it with the output signal of the piezoelectric element 2c. 6 is an output terminal of an operational amplifier which is a combining circuit.

Each circuit created in this way is as follows'
)+E+ri. A square column 1 is placed between the piezoelectric elements 2a and 2b.
When a signal having a resonant frequency is supplied, the prism 1 vibrates in the Z-2' direction in FIG. Here, x-x' same circumference 9
When a rotational force is applied t, the prism 1 exerts a Coriolis force Y
Since vibration also begins in the y/direction, signals are generated in the piezoelectric elements 2c and 2d. At this time, the pressure "jjj + element 2c,
The phases of No. 45 generated at piezoelectric element 2d are opposite to each other, and the signal generated at piezoelectric element 2d is inverted in phase by the piezoelectric element 2c. The signal generated at the piezoelectric element 2d is phase-inverted by the operational amplifier 5 and has the same phase as the signal 411 generated at the piezoelectric element 2c, so both the A signal and the signal are combined with the '11ε river summation. On the other hand, since the offset signal is not a regular vibration due to the Coriolis force, its frequency component includes not only the resonance frequency of the prism 1 but also its madder harmonics and subharmonics. The phases of the offset signals generated by the piezoelectric elements 2c and 2dK have no correlation with each other. Therefore, when the signals are combined by the operational amplifier 5, the power is added and the offset signal increases by 3 decibels. This means that the S/N ratio of the signal has improved by 3 decibels, and the offset has decreased.

In the above embodiments, a rectangular column is used as the vibrating body, but since it suffices if the vibrating bodies having vibrating surfaces perpendicular to each other are connected by a rigid body, two U The character-shaped tuning fork may be connected by a rigid body. Here, Fig. 4 is a front view, Fig. 5 is a plan view, Fig. 6 is a left side view, and Fig. 7 is a right side view.
a, 8bicl: Supporting member.

〔Effect of the invention〕

As explained above, in the angular velocity sensor according to the present invention, the output signals of the two sensors attached to the parallel vibration surfaces of the vibrating body configured to receive the Coriolis force are in phase. By adding them together in this way, the offset is reduced and detection can be performed with a small angular velocity, which has the effect of reducing the offset.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing the vibrating body of a vibrating gyroscope, Fig. 2 is a perspective view showing the vibrating body used in this invention in a state in which a compressed frost element can be seen, and Fig. 3 is an embodiment of the present invention. Figures 4 to 7 are circuit diagrams showing other embodiments of the unit. Figure 4 is a front view, Figure 5 is a plan view, Figure 6 is a left side view, and Figure 6 is a left side view. Figure 7 is a right side view. 11111@Reference prism, 28~2d11e-・Piezoelectric element,
3a, 3b * @ @ ”Support member, 4a, 4b a
* @ *Resistor, 5... operational amplifier, 6ψ...
Output terminal. Patent applicant: Jieko (2), company agent: Seijo Yamakawa (and 1 other person)

Claims (1)

[Claims] A vibration plane parallel to the first plane and a vibration plane parallel to the second plane perpendicular to the first plane? A vibrating body having a VilJ plane, a piezoelectric element attached to each vibrating plane, and a signal obtained from one of the piezoelectric elements parallel to either the first or second plane. The other pressure is inverted and combined with the signal obtained from the element (angular velocity sensor equipped with an H+ synthesis circuit).