RU2413926C1 - Detecting element for circular micromechanical vibration gyroscope - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: detecting element for a circular micromechanical vibration gyroscope consists of a base, an annular resonator and flexible suspensions. The resonator ring has a section which varies on the length. The width b and height h of the ring satisfy the relationship:

where K₁ and K₂ are constants; λ and λ_A are fixed compliance coefficients; E(Θ) is a periodic direction function (Young's modulus).

EFFECT: compensation for mechanical anisotropic properties of silicon and high accuracy of measuring angular velocities of the resonator.

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Description

The invention relates to gyroscopic devices and can be used in control systems of moving objects for various purposes as indicators of angular velocity.

To date, various designs of sensitive elements of a ring micromechanical vibrational gyroscope are known, for example, [1], [2], [3].

All existing, at the moment, designs of sensitive elements of a ring micromechanical vibrational gyroscope incorporate a ring resonator constant in cross section, suspended by means of elastic elements. Moreover, to improve the accuracy characteristics of the device, it is imperative that the frequencies of primary and secondary vibrations coincide.

Closest in technical essence to the claimed invention is a sensitive element (SE) of a ring vibration gyroscope, which contains a base, a resonator in the form of a silicon ring supported by eight radially elastic suspensions, which are fixed in the base. The ring resonator has a section of regular rectangular shape [3].

The known device has several significant disadvantages.

The design of the prototype involves its manufacture only in the silicon plane with an orientation of (111), since silicon in the remaining planes has a pronounced anisotropy of mechanical properties. The anisotropy of the mechanical properties, in turn, leads to a change in the stiffness of the ring resonator depending on the direction, which is a consequence of a significant difference in the natural frequencies of the oscillations of the ring resonator for the working form of vibration. The inequality of the oscillation frequencies of the ring resonator leads to a significant deterioration in the accuracy characteristics of the device.

The objective of the invention is to improve the accuracy of the ring micromechanical vibration gyroscope and the possibility of its manufacture in the silicon plane (100).

This problem is solved due to the fact that in the sensitive element of the ring micromechanical vibration gyroscope, including the base, ring resonator, elastic suspensions, according to the invention, the resonator is made in the form of a ring with a variable cross-sectional length, with the dependence of the width b and height h of the ring:

where K ₁ and K ₂ are constant coefficients.

It is known that the anisotropy of the mechanical properties of silicon as a structural material leads to a significant difference in the natural frequencies of the primary and secondary vibrations of ring resonators with a constant cross-sectional length, which extremely negatively affects the accuracy properties of the gyroscope [4]. This is because the flexural rigidity B for the ring resonator will also be anisotropic with a constant cavity cross section.

, фиг.2 [5].Note that the Young's modulus E of anisotropic materials is a periodic direction function, for example, the Young's modulus Si in the (100) plane is determined by the dependence

2 [5].

where λ and λ _A are constant compliance coefficients.

In the present invention, the resonator has a variable cross-section, while the cross-section is changed so that the bending stiffness of the resonator remains constant:

B = E · J = const,

where B is the bending stiffness, E is the Young's modulus, J = (bh ³ ) / 12 is the moment of inertia of the cross section, b and h are the width and height of the ring resonator, respectively.

Thus, in the proposed gyroscope, the width and height of the ring resonator made in the (100) plane changes according to the law:

where K is a constant coefficient.

In this case, one of the dimensions of the ring resonator can be rigidly fixed, and the other determined in accordance with the dependence:

where K ₁ and K ₂ are constant coefficients.

Figure 3 shows the sensitive element of the micromechanical vibration gyroscope, where 1 is a ring resonator with a variable cross section; 2 - elastic suspensions; 3 - base.

The device operates as follows.

In a ring resonator, resonant oscillations are excited on the second form of oscillation, the so-called primary oscillations. As a result of the action of the Coriolis forces, oscillations appear relative to the axis of sensitivity of the device, which is rotated 45 ° from the axis of the initial oscillations, the so-called secondary oscillations (Fig. 1). In a known manner, these oscillations are recorded and the magnitude of the signal is judged on the angular velocity.

Information sources

1. USA patent No. 5555765.

2. USA patent No. 6978674.

3. USA, patent No. 7267005, (prototype).

4. Zotov S.A. Analysis of the influence of the anisotropic properties of the material on the natural frequencies of ring resonators of micromechanical gyroscopes. University News. Electronics 2007, No. 5, p.30.

5. Terminal Yu.A. and others. Plasticity and strength of semiconductor materials and structures. - M.: Mechanical Engineering, 1982. 240 p.

Claims (1)

A sensitive element of a ring micromechanical vibration gyroscope, including a base, a ring resonator, elastic suspensions, characterized in that the resonator ring is made with a cross-section with a variable length, the dependence of the width b and the height h of the ring:

where K ₁ and K ₂ are constant coefficients;
λ and λ _A are constant compliance coefficients;
E (θ) is the periodic direction function (Young's modulus).

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