RU2556334C1 - Sensitive element of microsystem gyroscope - Google Patents

Abstract

FIELD: instrumentation.SUBSTANCE: sensitive element of a microsystem gyroscope comprises a case silicon plate, external and internal movable frames symmetrically located inside each other and separated with even gaps, at the same time the external frame is connected to the base silicon plate and to the internal frame by means of elastic torsions, longitudinal axes of each pair of torsions are mutually perpendicular, between the case silicon plate and the movable frames there is a gap formed by means of through anisotropic etching, to one side the case silicon plate an insulating liner is rigidly attached with applied fixed conducting electrodes of the electrostatic power converter setting forced oscillations of the internal frame, at the same time at both sides of the case silicon plate there are insulation liners attached, onto which electrodes of the electrostatic power converter are applied, which set forced oscillations of the internal frame, electrodes of the capacitance converter of movements and electrodes of the power electrostatic converter of feedback, the external movable frame is a movable conducting electrode of the electrostatic power converter of feedback, compensating the torque from action of Coriolis force, and the movable conducting electrode of the capacitance converter of movements.EFFECT: increased accuracy of measurements.2 dwg

Description

The invention relates to measuring technique and may find application in vibration-type integrated gyroscopes.

A known sensitive element of a planar inertial sensor [1], containing a layered glass-silicon-glass structure, wherein the movable assembly is made of monosilicon and consists of two frames: external, movable, suspended from the carrier plate on two torsion bars, and internal, movable, suspended on two torsion bars to the outside. The carrier plate is fixed rigidly to the fixed base by electrostatic welding.

The disadvantage of this device is the low accuracy due to the loss of vibrational energy of the frames given to the body plate.

Closest to the claimed invention can serve as a sensitive element of a microsystem gyroscope [2], containing a silicon case wafer, external and internal movable frames symmetrically located inside each other and separated by uniform gaps, while the outer frame is connected to the silicon wafer by means of a first pair of elastic torsions and at the same time, by means of a second pair of elastic torsion bars connected to the inner frame, and the longitudinal layers of each pair of torsion bars are mutually perpendicular , a gap is formed between the silicon wafer and the movable frames through anisotropic etching; on one side of the silicon wafer there is a rigidly insulated sheath with fixed conductive electrodes of the power transducer that excites primary vibrations of the internal frame, piezoelectric displacement sensors located on the second pair of elastic torsions take information on the primary vibrations of the internal frame to adjust their frequency, and the piezoelectric The displacement transducers located on the first pair of elastic torsions take information about the secondary vibrations of the external and internal frames that appear during the action along the axis perpendicular to the plane of the silicon wafer, the angular velocity.

A disadvantage of the known device is the low accuracy due to the fact that it does not fully compensate for the moment from Coriolis forces by the feedback moment, and it is also impossible to achieve the specified accuracy achieved by the predominance of the stiffness of the electric spring over the mechanical stiffness of the elastic torsion bars.

The problem to which the invention is directed, is to increase the accuracy of the microsystem gyroscope.

The technical result is the compensation of the Coriolis moment and the implementation of the ratio of the stiffness of the electric spring to the stiffness of the mechanical suspension with a predetermined value necessary to achieve measurement accuracy.

This technical result is achieved by the fact that in the sensitive element of the microsystem gyroscope containing the silicon housing plate, the outer and inner movable frames symmetrically located inside each other and separated by uniform gaps, while the outer frame is connected to the silicon shell plate and to the inner frame by means of elastic torsions, the longitudinal axes of each pair of torsion bars are mutually perpendicular, between the silicon wafer and the movable frames formed by a through nizotropic etching a gap, on one side of the silicon case plate is rigidly connected an insulation plate with fixed conductive electrodes of an electrostatic power converter applied to it, which sets the oscillations of the internal frame, the insulation plates on which electrodes of the electrostatic power converter are applied are rigidly connected forcing forced oscillations of the inner frame, capacitive transducer electrodes eremescheny electrodes and the electrostatic force feedback transducer, external movable frame is movable conductive electrode electrostatic force feedback transducer, the compensating moment of action of the Coriolis force, and the movable conductive electrode capacitance displacement transducer.

Compared with the known one, the Coriolis moment is compensated and the stiffness of the electric spring to the rigidity of the mechanical suspension is fulfilled with a predetermined value, the area of the outer frame is made at the request of creating a moment of power working out, sufficient to compensate for the moment of Coriolis force arising on the inner frame, and at the same time the time of power working out exceeds the moment from the elastic forces by an amount sufficient to ensure a given accuracy.

The proposed sensor element of the microsystem gyroscope is illustrated by the drawings shown in figures 1 and 2. Figure 1 shows a plan view of the movable node of the sensor element, and figure 2 shows one of two insulating plates with conductive electrodes deposited on its surface.

The sensitive element of the microsystem gyroscope contains (Fig. 1) a case silicon wafer 1. Inside the case of silicon wafer 1, movable outer frame 2 and inner frame 3 are symmetrically arranged in each other. The outer frame 2 is suspended from the casing plate 1 using torsion bars 4, and the inner one frame 3 is suspended from the outer frame 2 by means of torsion bars 5. The longitudinal axis of each pair of torsion bars 4 and 5 are placed perpendicular to each other. From the silicon wafer 1, the outer frame 2, with the exception of the attachment points of the torsion bars 5, is separated by through gaps obtained by anisotropic etching. Also, the inner frame 3 is separated from the outer frame 2 through the gaps with the exception of the places of connection of the torsion bars 4.

Two identical insulating plates (Fig. 2) are fixed rigidly from different sides to the silicon case plate 1 by means of an anode connection. The insulating lining 6 is made of ion-containing glass or non-conductive monosilicon. The following conductive electrodes are made on each plate by vacuum deposition: electrodes 7 of an electrostatic power converter; electrodes 8 of a capacitive displacement transducer; electrodes 9 for exciting forced vibrations of the inner frame. Through the contact pads, the electrodes 7, 8 and 9 are included respectively in the electrical circuit. Between the silicon wafer 1 and the electrodes on the insulating lining 6, when connected, a gap h is provided. Depending on the measurement limit of the microsystem gyroscope, this gap is selected from 5 to 25 micrometers.

The external movable frame 2 in this design acts as a gyro-sensitive unit, and the internal 3 as a gyromotor, and is forced into oscillations about the y axis using an electrostatic oscillator. The operation of the claimed device is as follows. In the absence of angular velocity Ω, the inner frame 3 oscillates with respect to the y axis and does not have them with respect to the x axis. Coriolis acceleration does not occur, the moment of power testing, of the electrostatic power converter must exceed the value of the elastic moment of the torsion bars by the reciprocal of the value of the required total error:

- момент электростатического преобразователя отработки; ε - диэлектрическая проницаемость среды в зазоре между проводящей подвижной рамкой силового преобразователя и неподвижным электродом силового преобразователя на изоляционной обкладке; ε₀ - диэлектрическая постоянная; F - площадь неподвижного электрода силового преобразователя; U_оп - величина опорного напряжения; U_max - максимальное значение выходного напряжения; h - зазор между проводящей подвижной рамкой силового преобразователя и неподвижным электродом силового преобразователя; М_упр - момент сил упругости торсионов; δ_Σ - требуемая величина суммарной относительной погрешности, внутренняя рамка с обеих сторон металлизирована так, что ее полярный момент инерции определяется следующим соотношением:Where $$M_{EL}=\frac{2\epsilon {\epsilon }_{0}FL{U}_{on}{U}_{\max }}{h^2}$$

- the moment of the electrostatic converter; ε is the dielectric constant of the medium in the gap between the conductive movable frame of the power converter and the stationary electrode of the power converter on the insulating lining; ε ₀ is the dielectric constant; F is the area of the fixed electrode of the power converter; U _op - the value of the reference voltage; U _max - the maximum value of the output voltage; h is the gap between the conductive movable frame of the power converter and the stationary electrode of the power converter; M _control - the moment of elastic forces of the torsion; δ _Σ is the required value of the total relative error, the inner frame on both sides is metallized so that its polar moment of inertia is determined by the following relation:

where ω is the frequency of forced vibrations of the inner frame; Ω _max - the maximum value (limit) of the measured angular velocity.

In the presence of a rotational speed Ω _z on the outer frame 2, an alternating gyroscopic moment arises, exciting in it oscillations about the x axis. The frequency of these oscillations coincides with the frequency of the forced oscillations of the inner frame 3, and the amplitude of the oscillations is proportional to the rotational speed.

Information sources

1. US patent No. 4598585, IPC G01P 15/02, NKI 73/505, publ. July 08, 1986.

2. US patent No. 5488862, IPC G01P 9/04, NKI 73.504.02, publ. February 06, 1996.

Claims (1)

A microsystem gyroscope sensitive element containing a silicon case wafer, external and internal movable frames symmetrically located inside each other and separated by uniform gaps, while the external frame is connected to the silicon wafer and the internal frame by means of elastic torsions, the longitudinal axes of each pair of torsions are mutually perpendicular, between the case silicon wafer and moving frames, a gap is formed through anisotropic etching, on one side of the body A silicon wafer is rigidly connected to an insulating cover with fixed conductive electrodes of an electrostatic power transducer applied to it, which determines the forced vibrations of the internal frame, characterized in that insulating plates are applied to both sides of the silicon wafer, on which electrodes of the electrostatic power transducer are applied, which determine the forced vibrations of the internal frames, electrodes of capacitive displacement transducer and electrodes of power elec of the feedback static converter, the external movable frame is the moving conductive electrode of the electrostatic power feedback converter, compensating for the moment from the action of the Coriolis force, and the moving conductive electrode of the capacitive displacement transducer.

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