WO2010024729A2

WO2010024729A2 - Micromechanical gyroscope and method for tuning thereof based on using of amplitude modulated quadrature

Info

Publication number: WO2010024729A2
Application number: PCT/RU2009/000447
Authority: WO
Inventors: Iakov Anatolevich Nekrasov
Original assignee: Otkrytoe Aktsionernoe Obschestvo "Kontsern "Tsentralny Nauchno-Issledovatelsky Institut "Elektropribor"
Priority date: 2008-09-01
Filing date: 2009-08-31
Publication date: 2010-03-04
Also published as: RU2008135886A; WO2010024729A3; RU2388999C1

Abstract

The invention relates to the field of micromechanics, in particular to vibratory micromechanical gyroscopes (MMG), wherein the movable mass (MM) displacement along the primary oscillations γ(t) axis changes according to the equation γ(t)≡sin (ω₁t). In order to adjust the parameters of suspension oscillating loops and parameters of electronic units of these gyroscopes, as well as to test their correct operation, a test action B(t)sin(ω₁t) is generated for the movable mass (MM) of the MMG. This action is generated by modifying the voltage at electrodes arranged above the lateral sides of the MM, or by connecting the signal source to the electrodes of the secondary oscillations channel of the MMG, said source being proportional to B(t)sin(ω₁t). The signal source may be formed by means of a modulator connected to the primary oscillations axis MM displacement transducers and voltage source B(t). The control signal for the systems for automatic adjustment of the MMG parameters is extracted by sequential demodulation of the signal of the secondary oscillations axis MM displacement transducer by means of demodulators with sin(ω₁t) and B(t) reference signals. To adjust the resonant frequency of the MMG suspension, the control signal passes to the electrodes of the secondary oscillations channel, while in case of adjusting the phase shift of the secondary oscillations channel signal said signal passes to the control input of the phase shifting circuit. For modification of scale factor of the MMG comprising a system for automatic adjustment of the resonant frequency, a device with the variable transmission coefficient is connected sequentially with the differentiating element. Continuous testing of correct operation of the MMG is performed by comparing the signals produced in the MMG under the effect of the test signal with reference signals.

Description

MICROMECHANICAL GYROSCOPE AND METHOD FOR TUNING THEREOF

BASED ON USING OF AMPLITUDE MODULATED QUADRATURE

Technical Field

The invention relates to the field of micromechanics, particularly to vibratory micromechanical gyroscopes (MMG) comprising circuits of adjustment of suspension oscillating loop parameters, parameters of electronic units of these gyroscopes and control of their operability.

In an MMG a movable mass (MM) is mounted on the base by means of at least biaxial resonant suspension. The chosen resonant frequency of the suspension along the primary oscillations axis is lower than the resonant frequency of the suspension along the secondary oscillations axis. There are possible different operating modes of the MMG: with coincident resonant frequencies as well as an operating mode with the frequencies of these suspensions slightly displaced against each other. Frequency difference and parameters of resonant suspensions must be constant so that the parameters of the MMG are constant. In case of 5% or greater difference between resonant frequencies the MMG parameters change to a significantly lesser extent than if this MMG is an MMG with resonant frequencies of suspensions brought together. Modification of one of these frequencies leads to a change in the difference of phases between the primary and secondary oscillations channel signals, and to a significant (several times greater) change in the scale factors of the MMG. Therefore, systems of automatic adjustment of parameters are used in order to retain constant MMG parameters with little difference in resonant frequencies. In these systems the estimation of certain MMG components response to a testing action is followed by adjustment. One of the components that are most sensitive to operational conditions change is a resonant suspension of the MM. Suspension resonant frequency change alters the coefficient of transformation of the micromechanical component (the correlation between measured angular rate and amplitude of the MM secondary oscillations) as well as the coefficient of transformation of electronic component due to a modification of the phase of the signal of the secondary oscillations axis MM displacement transducer, said signal coming to the input port of the synchronous detector with a reference signal of the primary oscillations axis MM displacement transducer. Therefore, systems for adjusting resonant frequency and/or phase are used in an MMG.

Background Art

In the system for adjusting the MM suspension resonant frequency (f₂) along the secondary oscillations axis to the frequency (fi) of the primary oscillations the Bosch company (US patent No. 6,553,883) uses a test signal consisting of two harmonious signals at the (fi±Δf) frequencies. Another patent of this company (US patent No. 6,654,424) proposes additionally using besides these signals a pair of signals of the same frequency being orthogonal to the first ones, i.e. shifted by 90° . The same solution for the resonant frequency adjustment is given by Chinwuba D. E. "Redout Techniques for High-Q Micromachined Vibratory Rate Gyroscopes" PHD Dissertation, University of California, Berkeley, 2007, p. 19, fig. 3.4. Here two signals (fl+Δf) are used as well, connected to the signal of the capacitive MM displacement transducer. This publication (pp. 17, 18) teaches that in case the test signal is used on the frequency of the primary oscillations, it will not be possible to reveal resonant frequency mismatch. This problem is solved by using two test signals, one with a higher and one with a lower frequency than the frequencies of the primary oscillations, meanwhile the frequencies of these test signals are chosen so that they are not within the desired range of the useful signal.

The Thales company suggested (US patent No. 7,159,461) using a frequency modulated signal as a test signal, its central frequency being equal to I₁ while frequency deviation being at the level O.lfi.

The Litef company suggested (US patent No. 7,278,312) using the noise voltage in the signal at the output of the secondary oscillations axis MM displacement transducer as a test signal.

As a test signal one can also use a quadrature as it is proposed in RU patent No. 2308682.

Test signals in micromechanical sensors are used not solely in the systems for stabilization of parameters of separate units. They may be used for monitoring the operability of these sensors, which is especially vital in case these sensors are used in systems and devices providing, for example, passenger safety in a vehicle. An example of such system for constant monitoring of the micromechanical sensor is given in US patent No. 7,086,270. Here a signal having a frequency which is higher than the real effect is used as a test signal, depending on the reaction of the micromechanical component of the sensor, the operability of which is determined.

In the report of Link T. et al . "A new self -test and self- calibration concept for micro-machined gyroscopes" Transducers ' 05 The 13^th International Conference on Solid-State Sensors Actuators and Microsystems, Seoul, Korea, June 5-9, 2005, pp. 401-404 an MMG is described, which is arranged in an additional suspension with electrodes providing not only for MM displacement around the axis of the secondary oscillations, but also for the displacement of the whole MMG around the sensitivity axis . This allows to set calibrating displacement imitating the displacement of the object and to evaluate and correct the MMG parameters judging by the response to the signals provided to the electrodes. This solution considerably sophisticates the micromechanical component of the MMG.

MMG testing may be conducted before or in the process of operating by transmitting a logic signal causing a shift of the sensor readings by a definite value as in ADIS16130 MMG by Analog Devices (see ADIS16130.pdf, p. 10) . A disadvantage of this solution consists in that the test effect causes a change in the sensor readings, which must be compensated, which in turn leads to MMG error growth (the shift in the sensor readings in testing depends on the environment, for example, on the temperature (see Fig. 12) and to the sophistication of signal processing algorithm.

In US patents No. 6,553,883, 6,654,424, 7,159,461, 7,086,270 test signals for the sensors with a high-frequency test signal are generated so that the test signal is out of the sensor bandwidth and hence this signal may be suppressed by means of filters; this ultimately reduces processing speed of the micromechanical sensors and sophisticates them. The disadvantage of the solution according to the US patent No. 7,278,312 consists in the sophisticated minimal noise value adjustment, while the device according to RU patent No. 2308682 functions only in the absence of the constant-sign measurable angular speed.

Thus, the use of test signals with a wave form that is known in the art in micromechanical sensors leads to a decrease in the processing speed to a degradation of a response speed of these transducers, to their sophistication or inoperability in certain circumstances .

A method according to US patent No. 6,553,883, which has some of the aforementioned disadvantages, was chosen as a prototype for the proposed method for generating a test action on the movable mass of a micromechanical gyroscope.

Disclosure of Invention

It is the object of the present invention to increase the MMG processing speed, to simplify its structure and to enhance its accuracy.

To achieve said object while generating the test action on the movable mass of the micromechanical gyroscope, displacement of said movable mass along the axis of primary oscillations Y changing in time (t) according to the following expression: Y (t) ≡sin (ωit) , wherein coi is an angular frequency, consisting in the modification of the voltage at the electrodes arranged along the axis of the secondary oscillations of the movable mass, the voltage U(t) at one or more electrodes is modified so that the harmonious component A(t) at the frequency coi having value:

' , changes according to the following da expression:

Λ(t)^≡5(t)sⁱnO/)_{^ wh}erein an amplitude B(t) ≠ const., C (α,γ(t)) is a capacity between the movable mass and electrode where the voltage is being varied, α denotes MM displacement along the secondary oscillations axis.

Moreover, to achieve the aforementioned object in the micromechanical gyroscope with an electrode structure, in case of oscillations of the movable mass along a primary oscillations axis, an overlapping area between the movable mass and one or more electrodes changes, the voltage at said electrodes is modified at a frequency less than a primary oscillation frequency. Moreover, to achieve said object in the micromechanical gyroscope with an electrode structure, in case of oscillations of the movable mass along the axis of the primary oscillations, an overlapping area between the movable mass and one or more electrodes does not change, the voltage at said electrodes is modified at a frequency which is equal to the frequency of the primary oscillations, in phase with the primary oscillations of the movable mass, thereby modifying the amplitude of said voltages.

The proposed method for generating a test signal provides generation of amplitude modulated quadrature torque or force. This torque (or force) is in phase with the quadrature, which is suppressed using methods known in the art, such as synchronous detection. Therefore, there is no need to sophisticate the electronic part of the MMG and to provide additional filters to suppress a response to the test signal. Thus, maximum MMG response speed can be maintained as there is no need to reduce the sensor bandwidth, leaving a part of the working frequencies range for the test signal. On the other hand, amplitude modulation of quadrature signal somewhat marks the test signal and allows to detect the MMG elements response particularly to the test signal, ruling out components associated with other signals and causes.

There are known electrode structures that provide for generating a torque or force in phase with quadrature. Such structures for an RR-type MMG are disclosed in US patent No. 6,067,858 (Fig. 20), RU patent No. 2320962, and for an LL-type MMG - in US patent No. 7,213,458 (Fig. 2) .

The drawback of the electrode structure disclosed in US patent No. 6,067,858 consists in the fact that its usage considerably enlarges the area which is occupied by the micromechanical component on the silicon board, while the drawback of the structure disclosed in RU patent No. 2320962 consists in the fact that, since the quadrature may be in phase or antiphase with the MM oscillations, the electrodes are arranged above the tooth (or finger) areas of the MM, on the both sides of the MMG sensitivity axis (electrodes 14, 16 and 15, 17 in Fig. 3 of RU patent No. 2320962) , although suppression of the quadrature due to generating of the quadrature torque of the necessary value and sign is achieved by means of only one pair of electrodes . The need for forming surplus electrodes and of their respective outputs sophisticates the construction and enlarges the area occupied by the micromechanical component of an MMG. The structure according to RU patent No. 2320962 has been selected as a prototype for the RR-type MMG. Among the drawbacks of the structure according to US patent No. 7,213,458 one may note that in case of high quadrature the area of the electrodes arranged above the tooth area of the MM may happen to be insufficient, and main electrodes arranged below the MM will have to be used in order to suppress the quadrature. In this case, to reduce the size of the MMG, it would be more reasonable to use the main part of the electrodes above the tooth area to measure MM displacement along the axis of the primary oscillations. This structure has been selected as a prototype for the electrode structure of LL- type MMG. An object of the invention for both proposed structures is to reduce the size of the MMG while generating a proposed test action on the movable mass.

To achieve this object in an RR- type MMG with an electrode structure comprising a movable mass having a form of sectors arranged symmetrically relative to sensitivity axes of the micromechanical gyroscope and secondary oscillations of the movable mass, and electrodes arranged above or below the movable mass to implement the proposed method for generating a test action, part of said electrodes is arranged above or below lateral borders of the sectors. To achieve this object in an LL- type MMG with an electrode structure comprising a movable mass having a form of a rectangle, the first pair of sides of said rectangle being perpendicular to the direction of the primary oscillations and the second pair of the sides of said rectangle being parallel to said direction; and electrodes being arranged above and below the movable mass, part of said electrodes is arranged above or below the lateral edges of one or both pairs of said sides.

Moreover, to achieve this object, the movable mass is provided according to the invention with openings oriented perpendicularly to the directions of the primary oscillations, and a part of the electrodes is arranged above or below the edges of said openings.

Unlike the prior art electrode structures generating torques or forces affecting the MM in phase with the primary oscillations, the proposed electrode structures do not need to generate an action of a high value (within the range of the MMG measurements and higher) , thus it is possible to provide electrodes with a significantly smaller area for generating a test action as compared to the prototype, and to arrange said electrodes in the micromechanical component of the MMG largely without any increase in its dimensions by using or modifying, for example, technological openings provided for silicon etching. There is also no need to provide surplus electrodes like it is proposed in RU patent No. 2320962, as this testing action should be both in phase and in antiphase with the quadrature . A method disclosed in US patent No. 6,553,883 has been selected as a prototype for the proposed method for adjusting a resonant frequency of a suspension of a movable mass along an axis of secondary oscillations, said prior art method having certain drawbacks originating from the method for generating a testing action that is used in said prototype method.

Accordingly, an object of the present invention is an increase in the MMG processing speed, its simplification and enhanced accuracy.

To achieve this object, the voltages at the electrodes arranged along the axis of the secondary oscillations are modified depending on the component of a signal of a secondary oscillations axis movable mass displacement transducer, said component being proportional to amplitude B(t), when adjusting the resonant frequency of the movable mass suspension along the secondary oscillations axis .

Moreover, to achieve this object, the component being proportional to the amplitude B(t) is extracted by sequential demodulation of the signal of the secondary oscillations axis movable mass displacement transducer first with a reference signal that is in phase with the primary movable mass oscillations and then with a reference signal that is proportional to B(t) .

Substantially due to said double demodulation, the proposed method provides first for the extraction of the quadrature signals, and consequently for selecting among these signals of one with amplitude changing proportionally to B(t) . And, depending particularly on this extracted signal, the voltages of electrodes in the MMG are measured in order to adjust a resonant frequency of the suspension along the axis of the secondary oscillations in accordance with the frequency of the primary- oscillations.

An MMG disclosed in RU patent No. 2320962 has been selected as a prototype for the device for implementing the proposed method for adjusting the resonant frequency, said prototype having a drawback consisting in low sensitivity due to operation in the mode with a 3% off -tuning of the resonant frequencies of the suspensions. For operation of the MMG with matching resonant frequencies of the suspensions it is necessary to connect a frequency adjustment circuit, which will implement the proposed method, into the MMG.

Therefore, one of the objects of the present invention is an enhancement of the MMG accuracy.

To achieve this object, in an RR- type MMG implementing the proposed method for adjusting the resonant frequency and comprising a movable mass in a form of sectors arranged symmetrically relative to the axes of sensitivity of the micromechanical gyroscope and secondary oscillations of the movable mass, the lateral surfaces of these sectors comprising teeth, three pairs of electrodes arranged above the movable mass and also having a form of sectors, the first pair of electrodes being arranged above the tooth areas of the movable mass that are arranged on one side relative to the sensitivity axis of the micromechanical gyroscope, the second pair being arranged symmetrically relative to said axis, and the third pair of electrodes being arranged on said axis, the electrodes of each pair being arranged symmetrically to the axis of secondary oscillations; stators mounted on the base and having teeth, forming together with the teeth of the movable mass a comb electrode structure; a suspension in a form of torsions, by means of which the movable mass is suspended to the support arranged on the base; a primary oscillation excitation device disposed between the stators and comprising a first movable mass displacement transducer and an electric signal transformation device; a second movable mass displacement transducer in a form of a differential transresistive amplifier with inputs connected to the first pair of electrodes; a DC voltage source connected to the second pair of electrodes, a first demodulator with an input connected to the output of the transresistive amplifier and a reference signal input connected to the output of the first movable mass displacement transducer, said MMG further comprises an AC voltage source connected in series with the DC potential source; a second demodulator with an input connected to the output of the first demodulator and a reference signal input connected to said connected AC voltage source; and an integrator with an input connected to the output of the second demodulator and the output connected to the third pair of electrodes.

An MMG disclosed in the article by Peshekhonov [Peshekhonov et al. Rezultaty razrabotki mikromekhanicheskogo giroskopa (The Results of Micromechanical Gyroscope Development) . XII Saint Petersburg International Conference on integrated navigation systems, May 23-25, 2005, PP. 268-274, Fig.2, 3] has been selected as a prototype for another variant of the device for implementing the proposed method for adjusting the resonant frequency, said prototype having a drawback consisting in a low sensitivity due to operation in the mode of 3% off -tuning of the resonant frequencies. For the operation of MMG with matching resonant frequencies of the suspensions it is necessary to connect a frequency adjustment circuit, which will implement the proposed method, into the MMG.

To achieve this object, in an RR- type MMG implementing the proposed method for adjusting the resonant frequency and comprising a movable mass in a form of sectors arranged symmetrically relative to the axes of sensitivity of the micromechanical gyroscope and secondary oscillations of the movable mass, the lateral surfaces of these sectors comprising teeth; two pairs of electrodes, the electrodes in each pair being arranged symmetrically relative to said axes above the movable mass,- the electrodes of the first pair being electrodes of a capacitive secondary oscillations axis movable mass displacement transducer while the electrodes of the second pair being electrodes of a capacitive torque motor; stators mounted on the base and having teeth, forming a comb electrode structure with the teeth of the movable mass; a suspension in a form of torsions, by means of which the movable mass is suspended to the support arranged on the base; a primary oscillation excitation device disposed between the stators and comprising the first movable mass displacement transducer and an electric signal transformation device; a second movable mass displacement transducer in a form of a differential amplifier with inputs connected to the electrode of the first pair,- a first demodulator with an input connected to the output of the second movable mass displacement transducer and reference signal input connected to the output of the first movable mass displacement transducer; amplifiers with outputs connected to the electrodes of a torque transducer, characterized by having an AC voltage source, a second and a third demodulator, and a modulator, in said MMG the outputs of the second and the third demodulator are connected to an output of the summing device and with the same inputs of the amplifiers correspondingly via a first and a second integrator; the AC voltage source is connected to the modulator via the summing device, the output of said modulator being connected to the opposite inputs of the amplifiers, the reference signal inputs of the second and the third demodulators and of the modulator are coupled, correspondingly, with the output of the second movable mass displacement transducer via a 90° phase shift device, with the AC voltage source and with the output of the second movable mass displacement transducer via the phase shifter.

A method disclosed in RU patent No. 2282152 is an analogue of the proposed method for identifying a phase shift of a signal in the secondary oscillations channel relative to a signal of the primary oscillations channel movable mass displacement transducer in an MMG. Modification of this phase shift is identified according to the value of the constant frequency component on the output of a demodulator, which is to suppress quadrature. I.e. in this device a quadrature is used as a test signal. The drawback of this method consists in the fact that it may be used only in case the measurable MMG angular velocity does not comprise a constant component, otherwise the constant component of the signal which is associated with the measurable angular velocity cannot be distinguished from the constant component associated with modification of the phase between reference signal and quadrature. The possible solution to this problem proposed in said patent, consisting in a modification of the mode of operation in case of object circulation makes it difficult to use the MMG.

A method for adjusting the difference of phases between signals in the channels of the primary and secondary oscillations, which is disclosed in US patent No. 6,553,883, has been selected as a prototype. According to said patent, a test signal is used to adjust the resonant frequency of an MM suspension circuit along the axis of the secondary oscillations in accordance with a frequency of primary oscillations, which provides a constant 90° phase shift caused by the secondary oscillations circuit. A drawback of this method consists in the fact that in some cases it is reasonable to operate with an off -tuning of the resonant frequencies (e.g. if it is necessary to provide a constant scale factor or constant MMG scale factor, and/or a sufficiently wide bandwidth), when the phase shift is 90° , and the use of two test signals makes it necessary to introduce filters for suppress these signals, and, as a consequence, a reduced MMG processing speed.

Accordingly, among the objects of the present invention there is an enhanced MMG processing speed, its simplification and accuracy enhancement . To achieve this object, the identification of the phase shift of the signal in the secondary oscillations channel relative to a signal of a primary oscillations channel movable mass displacement transducer in an MMG comprising at least one electrode arranged non-coaxially to the direction of the primary oscillations of the movable mass, and a B(t) voltage source connected to said electrode, comprises: primary synchronous detecting of the signal of the secondary oscillations channel movable mass displacement transducer by means of a first reference signal, a signal of the primary oscillations channel movable mass displacement transducer being used as a first reference signal, and further comprises secondary synchronous detecting, the secondary synchronous detecting is performed by means of a second reference signal, the voltage B(t) being used as said second reference signal; and modifying the phase of the first reference signal until the average value of the signal equals 0 after the secondary synchronous detecting.

A method disclosed in RU patent No. 2282152 and US patent No. 6,553,883, correspondingly, were selected as analogues for the proposed method for identifying a phase shift of a signal in the secondary oscillations channel relative to the signal of the primary oscillations channel movable mass displacement transducer in an MMG. A compensation-type MMG having a channel for adjustment of the secondary oscillations axis resonant frequency disclosed in US patent No. 7,278,312 has been selected as an analogue for the proposed device .

The drawbacks of the prototype and the analogues are mentioned above.

The object of the present invention is an enhanced MMG processing speed, its simplification and accuracy enhancement.

To achieve said object, in an MMG comprising a movable mass in a form of sectors arranged symmetrically relative to the axes of sensitivity of the micromechanical gyroscope and secondary oscillations of the movable mass,- a resonant suspension of the movable mass in a form of torsions, by means of which the movable mass is suspended to the support mounted on the base; a comb electrode structure; a primary oscillation excitation device with inputs and outputs connected to the corresponding electrodes of the comb structure; electrodes arranged along the axis of the secondary oscillations, said electrodes having a form of sectors, wherein at least one of the electrodes is arranged above the lateral border of one of the sectors; a first capacitive primary oscillations axis movable mass displacement transducer; a second secondary oscillations axis movable mass displacement transducer, wherein the inputs of the first and second demodulators are connected to the output of the second movable mass displacement transducer, the outputs of said demodulators being connected, correspondingly, to the inputs of the first and second modulators via amplifying elements, the reference signal inputs of the same modulators and demodulators are connected to the output of the first movable mass displacement transducer via the first and second phase- shifting networks, the outputs of the modulators being connected to at least one of the electrodes arranged along the axis of the secondary oscillations via a summing device, said MMG further comprises an AC voltage source with the output connected to the electrode arranged above the lateral border of one of the sectors; a controllable third phase-shifting network; a third demodulator and integrator connected in series, wherein the inputs of the third demodulator are connected to the output of the first demodulator and the output of the connected AC voltage source, the output of the integrator is connected to the control input of the third phase-shifting network, which is connected between the output of the first movable mass displacement transducer and the inputs of the first and second phase-shifting network.

Due to the aforementioned elements that are further comprised by the proposed compensation- type MMG, the phase of the reference signal is adjusted so that the signal reflecting the MM displacement caused by test action generated according to the method of the present invention is entirely suppressed in the angular velocity extraction channel through precise adjustment of the demodulator reference signal phase.

A device disclosed in US patent No. 6,553,883 has been selected as a prototype for the proposed device implementing the proposed method for generating a test action. Here the introduction of a damping connection provides for a Q factor decrease in the secondary oscillations channel (see Fig. 4) . A drawback of this prototype consists in that the scale factor of this MMG is set by the manufacturer. It is determined by the programmed damping term coefficient. In case the MMG is used when the range of the measurable MMG angular velocities changes, it is reasonable to modify the MMG scale factor in order to enhance the MMG sensitivity at the cost of a reduced processing range. The prototype lacks this functionality.

The object of the present invention is a broader MMG functionality and an enhanced accuracy of an MMG.

To achieve this object, in a micromechanical gyroscope with an automatic frequency adjustment circuit and a damping feedback in the secondary oscillations channel, which is realized in the form of a differentiating element disposed between the output of axis movable mass displacement transducer and the electrodes arranged on said axis, said micromechanical gyroscope further comprises a variable gain device that is connected in series with said differentiating element.

Moreover, to achieve this object, in a micromechanical gyroscope with an automatic frequency adjustment circuit and a damping feedback in the secondary oscillations channel, which is realized in the form of a differentiating element disposed between the output of axis movable mass displacement transducer and the electrodes arranged on said axis, and a variable gain device, said gyroscope comprises an input value modulus average extraction device, an output of said device being connected to the gain coefficient modification input and an input of said device being connected to the input of the variable transmission coefficient device.

The connected variable transmission coefficient device allows to modify the MMG scale factor according to the signal of the external control signal source. As this signal, an output signal of the MMG may be used, and an automatic adjustment of the MMG sensitivity may be performed depending on the range of modification of current values of the measured angular speed.

The above-discussed method for continuous testing of correct operation of a micromechanical gyroscope disclosed in US patent No. 7,086,270 has been selected as a prototype for the proposed method for MMG testing.

One of the objects of the present invention is an enhanced MMG processing speed, simplification of its structure and continuous testing of its correct operation.

To achieve this object, an amplitude-modulated force

(torque) is used as a test signal, said force being in phase with the force that causes quadrature, which is generated by modification of the voltage of electrodes arranged along the secondary oscillations axis of the movable mass, while the response to this test signal is determined by primary demodulation of the output signal of a secondary oscillations axis movable mass displacement transducer using the reference signal on the frequency of the primary oscillations and secondary demodulation using the reference signal proportional to B(t) .

Brief Description of the Drawings

The proposed method is illustrated in the Figures.

Fig. 1 is a block diagram of the secondary oscillations. Fig. 2 is a view of the test action on the MM and effect associated with Coriolis acceleration;

Fig. 3 shows a variant of the prior art electrode structure (patent RU No. 2320962) which can be used to form the proposed test action on the MM. Fig. 4 is a block diagram of the MMG variant, in which there is used a proposed method of forming the test action on the MM for forming channels of adjustment of resonant frequency and suppression of the quadrature. Fig. 5 is a view of the electrode structure of LL-type MMG for realization of the proposed method of producing test action.

Fig. 6 is a block diagram of the MMG variant based on the proposed method of detecting signal shift phase in the channel of the secondary oscillations relative to the signal of the primary oscillations channel movable mass displacement transducer in the MMG and adjustment of the resonant frequency.

Fig. 7 is a block diagram of the MMG variant based on the proposed method of detecting signal shift phase in the channel of the secondary oscillations relative to the signal of the primary oscillations channel movable mass displacement transducer in the MMG and adjustment of this phase shift.

Fig. 8 is a part of the block diagram of the MMG variant based on the proposed method of detecting the signal shift phase in the secondary oscillations channel relative to the signal of the primary oscillations channel movable mass displacement transducer in the MMG and adjustment of this phase shift. A signal formed in this way is used in the MMG to form a force

(torque) feedback.

Fig. 9 represents a variant of the block diagram of MMG, in which the proposed method of resonant frequency adjustment and MMG micromechanical component scale factor modification depending on the measured rate is used.

Fig. 10 represents an example of the embodiment of the element 115 with a variable transmission coefficient. Fig. 11 shows an example of the MMG embodiment in which there takes place continuous testing of the MMG operability and its indication.

Best Mode for Carrying Out the Invention

The proposed method consists in the following: In Fig. 1 the elements are connected in the following way: Primary oscillations channel 1 has outputs Y and dγ/dt which correspond to the displacement of the movable mass (MM) indicated in Fig. 3 as MM 15, along the axis of the primary oscillations and to the speed of this displacement. These values pass on to the inputs of the elements 3, 4 with coefficients Kl and K2 correspondingly. The third input of the block 1 corresponds to the output of the capacitive MM displacement transducer, it is an electric signal proportional to the value Y, which is used as a reference signal of the demodulator 8. An input signal of block 3 is multiplied by angular velocity Ω around the MMG sensitivity axis in block 5. Input signals of blocks 5 and 4 are values of the forces or torques (depending on the type of MM: LL- or RR-) correspondingly associated with the Coriolis acceleration and quadrature. These torques are summed up by with element 6, its output is connected to the input of the MMG micromechanical component 2 of the channel of the secondary oscillations, which is represented in the form of the resonant element of the second order. An output of this element α is connected to the inputs of the demodulator 8 and regulator 9 via the secondary oscillations axis MM displacement transducer. The input of the regulator 9 is connected to the input of the forces (or torques) electrostatic summer 6 of the forces (or torques) affecting the MM via the electrostatic force (or torque) transducer 10. To generate a test action on the MM on the secondary oscillations axis, the voltage UT passes to the input of the element 10.

The secondary oscillations channel of the MMG functions in the following way: Force F affecting the MM 15, comprises four components:

F=KlΩdγ/dt + K2γ+K3Uoc+K4Uτ, (1) wherein K3 , K4 are coefficients of proportionality.

Meanwhile

, (2)

Wherein γθ is an amplitude of the primary oscillations . It should be noted that signal Uoc may help to provide a decrease in the Q factor in the channel of the secondary- oscillations and to suppress the quadrature (see US patent No. 6,553,883) . Test signal UT may be transmitted not directly to the torque transducer, but to the input of the block 10.

As aforesaid, in the prototype of the present invention two test signals are generated being equidistant by frequency from ωl to determine the difference of the resonant frequency of the suspensions . Unlike the prototype and analogues according to the proposed method, the voltage U(t) on one or more electrodes is modified so that harmonious component A(t) at frequency ωi of the value

(that is a derivative of the accumulated da energy in the capacitors, formed by the conductive MM and electrodes arranged along the secondary oscillations axis, by displacement α) changes according to the equation:

v ' ^v ' ^v ' ' wherein amplitude B(t) ≠ 0.

Fig.2 shows that the test signal 11 is in the form of an amplitude-modulated harmonic curve (in Fig.2 the harmonic signal 13 is a modulation function) . This harmonic curve is moved to

90° relative to the effect associated with Coriolis acceleration

12, that is in phase with quadrature. However, unlike the quadrature having the constant or slowly changing amplitude (due to the changes of the environment or MMG obsolescence) , the test signal amplitude may be modified to have quite a high frequency

(necessary frequency of modification is determined by the processing speed of the transformation circuit) and an intricate shape. For example, this amplitude may change randomly according to known algorithms and random number or value generation programs .

An example of test action generation is shown on Fig. 3. Here the MM 15 consisting of disk sectors is arranged below electrodes 16, 17 and 20. Symmetrically to these electrodes other three electrodes (16a, 17a and 20a) are arranged. Lateral surfaces of the disk sectors have teeth 18, 19, which together with stators teeth (not shown in Fig. 3) form comb primary axis displacement transducers and a torque transducer. Teeth 18, 18a are arranged below electrodes 17, 17a. The disk is suspended by means of torsions on the support 23 to which DC and/or AC voltage may be applied. Torsions, support 23 and MM 15 are made of doped silicon and thus may be regarded as conductors. AC and DC voltage sources 21 and 22, correspondingly, are sequentially connected to the electrode 17 (or to two electrodes arranged above the tooth areas of the MM on one side of the Y axis, for example, to electrodes 17 and 17a) . More detailed description of this electrode structure is given in RU patent No. 2320962, where it is shown that primary oscillations of the MM 15 change the overlapping area between electrodes 17, 20, 20a and MM 15, which, in case of different voltage on these pairs of electrodes (17, 17a and 20, 20a), leads to the occurrence of a torque in phase (or in antiphase) with quadrature.

In case voltage U₂₃ is applied to the MM in order to actuate displacement transducers, and voltage of the sources 21, 22 equals correspondingly U₂i, U₂₂, U₂₃=A₂₃sin(ω₂₃t) , ω₂₃>>ωi, (3) U₂i=A₂isin(ω₂it) , ω₂i<ωi, (4) U₂₂=A₂₂=const, (5) , then taking into consideration the change in the overlapping area between electrodes above the tooth sectors of the MM 15 in case the position of the MM along the primary oscillations axis changes according to the equation (2), the torque M formed by these voltages about the axis X at the frequency ωi is proportional to

M≡(U₂₁ +U₂₂)² sin(G)!t) , (6) .

Substitution of equations ( 4 ) , ( 5 ) into the equation ( 6 ) will give :

M≡ [ (A₂₂ ) ² + 0 , 5 (A_2x ) ² - 0 , 5 (A₂₁) ²cos ( 2ω₂₁t ) +2A₂₂A₂isin ( ω₂₁t ) ] sin ^t ) , ( 7 ) . Assuming that values A₂₃, A₂₁ are constant, a torque that compensates quadrature may be formed in the MMG by means of modification of the constant value A₂₂, and a torque in phase with quadrature with amplitude changing with frequencies ω_2i and 2ω₂₁, may be formed. The response of the element 2 to at least one of these components may be used for diagnostics of the micromechanical component of the MMG.

Electrodes of RR- type MMG shown on Fig. 4 comprise stators 24, 25 of the capacitive primary oscillations axis MM position transducers, which have teeth on the lateral surfaces and together with MM teeth form a comb electrode structure, a pair of power electrodes 28, 29 and a pair of electrodes 30, 31 of the capacitive secondary oscillations axis MM position transducer. A more detailed description of the MMG is given in Peshekhonov V. G. et al . Rezultaty razrabotki mikromekhanicheskogo giroskopa (The Results of Micromechanical Gyroscope Development) . Gyroscopiya i navigatsiya (Gyroscopy and Navigation) . - 2005. - No.3 - pp. 44-51) .

The first 90° phase shifting device 32 for the electric signal and the first AC voltage source 33 are sequentially connected to the support 23.

The input of the first differential amplifier 34 and the input of the second differential amplifier 35 are connected to electrodes 30, 31. These amplifiers may have the form of transresistive amplifiers.

The reference signal inputs of demodulators 36, 37 are connected to the first AC voltage source 33, and signal inputs of these demodulators are connected to the outputs of the amplifiers 34, 35, correspondingly. The inputs of the third demodulator 38 are connected to the outputs of the demodulators 36, 37.

The inputs of the forth demodulator 41 are connected to the output of the demodulator 36 and are connected via the second 90° phase shift device 39 for the electric signal to the demodulator 37. The inputs of the fifth demodulator 47 are connected to the second AC voltage source 43 and to the output of the third demodulator 38.

The output of the forth demodulator 41 is connected via the integrator 42 and the first summing device 44 to one input of the modulator 45. Meanwhile, another input of the summing device

44 is connected to the second AC voltage source 43. Another input of modulator 45 is connected to the output of demodulator

36 via the phase shifting device 40 for the electric signal. The output of the fifth demodulator 47 is connected to the same inputs of the first and the second amplifiers 50, 51 via the second integrator 48. Outputs of the modulator and differentiating device 46 are connected to the opposite inputs of these amplifiers, the input of said modulator being connected to the output of the demodulator 37.

Test action is generated in the following way.

Primary oscillation axis MM displacement γ is harmonic and is described by equation (2) . By means of the capacitive transducer (which comprises stators 24, 25) of the converter "capacity - voltage" on the elements 34, 36 these oscillations are transformed into the electric signal

U₃₆=A₃₆SIn(Q_Xt -Δφ) (8), which due to the delay in the lowest frequencies filter of the demodulator 36 can lag at the angle Δφ relative to the oscillations γ(t) . Using the element 40, this lag may be compensated and in this case a signal in phase with γ(t) will pass to the input of the modulator 45. An output signal of the element 44, which may comprise a constant element (A₄₂) from the output of the integrator 42 and signal U₄₃=A₄₃SIn (ω₄₃t) (9), passes to another input of modulator 45.

Taking into consideration that a constant voltage U₄₈ passes from the output of the integrator 48 to the inputs of the amplifiers 50, 51, these amplifiers have the same polarity, while a signal from the output of the element 45 passes to the opposite inputs of these amplifiers, then

after the aforementioned modifications according to the equation for the torque M, a resulting equation may , contain a component sin(ω₂it) sin(ωit) as in the equation (9) . Thus, a test action on the MM may also be generated in an MMG with an electrode structure with a non-variable overlapping area between the MM and the electrodes along the secondary oscillations axis.

Fig. 5 shows a structure of an LL-type MMG. Here MM 52 is suspended by means of torsions 58, which are fixed to the , supports 57 mounted on the base. On the base an electrode 53 is arranged below the MM 52, said electrode forming together with the MM 52 a capacitive secondary oscillations axis MM displacement transducer. A stator 55 with teeth 56 is also arranged on the base. Lateral surfaces of the MM 52 also have teeth 54, which together with teeth 56 form a comb electrode structure used to form capacitive displacement and torque transducers. Fig. 5 shows a possible arrangement of the auxiliary electrodes intended for generating the proposed test action. Besides the above described arrangement of the electrodes above or below the MM teeth these electrodes may be arranged outside the tooth area as it is shown for the group of electrodes 59, which are arranged on the periphery of the lateral surface, or between the teeth as it is shown for the group of electrodes 60.

The principle of test signal generation is similar to the one described in respect of electrodes arranged above the tooth area. In both cases, MM displacement changes the overlapping area between the MM and corresponding electrodes, on which the temporally varying voltage is generated. As a result, a force or a torque is generated that affects the MM in the same phase as a torque causing the quadrature with an amplitude that is temporally varying according to the known rule. The main difference between the electrode structure in Fig.5 and in Fig.3 is the value of the test action, which is proportional to the overlapping area. The value of the overlapping area is of great importance for suppression of the quadrature, however the test signal necessary for the proper processing of the adjustment system and conducting diagnostics may exceed by several factors of ten the value of quadrature which is to be suppressed.

In Fig. 6 the elements are connected in the following way:

The inputs of the differentiating amplifier 61 are connected to the stators 24, 25 of the capacitive primary oscillations axis MM displacement transducer. The inputs of the differential amplifier 62 are connected to the electrodes 20, 20a.

The reference signal inputs of demodulators 63, 64 are connected to the first AC voltage source 33, and signal inputs of these demodulators are connected to the outputs of the amplifiers 61, 62, correspondingly.

The outputs of the demodulators 63, 64 are connected to the inputs of the demodulator 65. The inputs of the demodulator 66 are connected to the outputs of the demodulator 65 and to the source 21. The output of the demodulator 66 is connected to the electrode 16 via the integrator 67.

Generation of a test signal in the MMG with such electrode structure is described above.

Alongside with the torque associated with Coriolis acceleration the MM is affected by the generated test signal. Taking into consideration only the term with the element sin(ω₂it), the summing torque M_∑ will be

M_Σ = kiΩ(t) cos (ωit) +k₂sin(ω₂it) ) sin(ωit) (10), wherein k₁₍k₂ are coefficients.

Under the effect of this torque, the displacement of the MM along the axis of the secondary oscillations may be described by the following equation: α(t) = k(Δω) (k]Ω(t),cos (ωit+ψ (Δω) ) +k₂sin (ω_2it) ) sin (ωit+ψ (Δω) )

(11), wherein Δω=ω₂-ωi, while k(Δω) and ψ(Δω) are correspondingly a scale factor and a phase shift caused by the resonant suspension, correspondingly, which depend on the off-tuning of the resonant circuits or the difference of their resonant frequencies cύi , ω₂.

The high-frequency voltage of the source 33 causes current flow through the electrodes of the capacitive transducers, which depend on the values of the capacity between these electrodes and the MM. These currents are amplified by the amplifiers 61, 62 and then are transformed by demodulators 63, 64 into electric signals proportional to the MM displacement (γ, α) along the corresponding axes.

The low- frequency component of the sum of electric signals which are proportional to the displacements Y, α will comprise terms which are proportional to values Ω(t) sin(ψ (Δω) ) and sin (ω₂it) cos (ψ (Δω) ) . This component is detected by the demodulator 65.

In case of overlapping of resonant frequencies (Δω=0) angle ψ=90° and the component of the signal on the frequency ω_2i (i.e. the one associated with the test action) equals 0, while the component, which is proportional to Ω(t) , possesses the maximum value .

In order to adjust the resonant frequency ω₂ in the demodulator 66, the voltage of the source 21 is used as a reference signal .

The low- frequency component of the product of a signal being a sum of the signals (Ω (t) sin(ψ (Δω) ) + sin (ω_2it) cos (ψ (Δω) ) ) , and a reference signal sin(ω_2it) is detected by the demodulator 66. This component is proportional to cos(ψ(Δω) . Therefore, if this component is transmitted via the integrator to the electrodes arranged along the secondary oscillations axis, the resonant frequency ω₂ will change due to the known change in the negative rigidity until the input signal equals 0, which takes place at ψ=90° .

Thus, the proposed method for generating a test action and adjusting the frequency provide for the desired adjustment of the resonant frequency of the MM suspension. It may be noted that amplifiers 61, 62 may have the form of a transresistive differential amplifier, electrodes 24a, 25a may be additionally used to form an MM 15 displacement transducer, MM 15 is electrically connected to the support 23, therefore the common electrode of all capacitive transducers may be denoted as MM 15 and as support 23.

In the MMG shown in Fig. 4 the test action is generated by means of elements 43-45 and 49-51, as described above. A torque generated by means of these elements produces the components of the MM oscillations with frequency ωi, which are orthogonal to the oscillations caused by Coriolis acceleration. The amplitude of these oscillations changes with frequency ω₄₃ of the voltage source 43. In case the frequency ωi and ω₂ match, the signal at the output of the demodulator 38 is in phase with the oscillations caused by the Coriolis acceleration and orthogonal to the oscillations with amplitude changing with frequency ω₄₃. Therefore, in case the frequencies ωi and ω₂ match, only one signal, which is proportional to the angular speed Ω, is present at the output of the demodulator 38. In case there are no components with frequency ω₄₃ in the band of the signal at the output of demodulator 38, the output signal of demodulator 47 turns to be equal to 0.

In case ωi ≠ ω₂, a constant component caused by the quadruature occurs at the output of the demodulator 38, as well as a component at frequency ω_43. The latter is transformed into DC voltage by demodulator 47, said DC voltage leading to a growing or reducing output voltage of the integrator. Accordingly, the voltages at the electrodes 28, 29 change, and, due to the changes in the negative rigidity, this makes frequency ω₂ change until it becomes equal to ωi .

In case of the adjustment to resonance (ω_x = ω₂) , the demodulator 41 produces a DC voltage proportional to the quadrature, said voltage passing via the integrator 42 to the modulator 45, which forms the voltage at a frequency with the phase matching the MM primary oscillations. This voltage, passing to the electrodes 30, 31 in antiphase in the presence of DC voltage between the MM and these electrodes, generates a torque which suppresses the quadrature .

Due to the differentiation of the output signal of the demodulator 37 by the element 46 and forming of antiphasal voltages at the electrodes 28, 29 from the output signal of the element 46, a decrease in the Q factor of the suspension along the secondary oscillations axis is provided in the MMG. Here it should be noted that in case of the high Q factor value of the suspension in the secondary oscillations channel during the adjustment to the resonance, the transmission coefficient of the element 46 (or, more precisely, of the path from the capacitive secondary oscillations axis transducer, demodulators 35, 37, amplifiers 50, 51 and torque .transducer at the electrodes 28, 29) determines the scale factor of the MMG.

Thus, it is shown that the proposed methods for generating a test action and adjusting the frequency provide the necessary adjustment of the resonant frequency of the MM suspension in the MMG with an electrode structure, which does not have electrodes with the overlapping area that is variable at MM oscillations along the axis of the secondary oscillations.

In Fig. 7, unlike what is shown in Fig. 6, a controllable phase shifting device 68 for the electric signal is connected between the output of the demodulator 63 and the input of the demodulator 65, while the output of the integrator is connected to the control input of the element 68.

The proposed method for identifying the phase shift of the signal is based on the analysis of a response to the test signal, which is generated by means of the voltage source 21 and electrodes connected to it. MM oscillations along the secondary oscillations axis generated thereby are phase-modulated by quadrature as aforesaid. The signal being proportional to the amplitude of these oscillations may be detected by means of sequential demodulation of the signal of capacitive secondary oscillations axis transducer performed by demodulators that use reference signals being a signal of the capacitive primary oscillations axis transducer of the MMG and the source 21, correspondingly. This signal becomes equal to 0 only in case of a phase shift between the signals of the demodulator being equal to 90°. In case it is not 90°, the input signal of the integrator 67 will change and will correspondingly change the phase shift caused by the element 68 until said shift is achieved. The voltage at the input of the element 68 (at the output of the integrator 67) determines the phase shift value necessary for the compensation of phase shift between the capacitive transducer signals deviation from 90°.

Thus, it is possible to identify the desired phase shift taking into consideration the measured voltage value at the output of the element 67 and known functional dependence between the phase and voltage of the element 68.

It should be noted that it is possible to reduce the range of output voltages of the element 67 if an element with a constant phase shift desirable for the chosen mode of the MMG processing is connected sequentially to the element 68. For example, if the MMG operates with off -tuning at the level of 3-5% of resonant frequency, this constant phase shift approximates 90°. The advantage of an MMG in which this method for identifying and stabilizing the phase shift between the capacitive transducer signals is used consists in a complete suppression of the quadrature by the demodulator 65.

We should note that inputs of the element 62 may be connected to the electrodes 16, 16a without any changes in the processing of the phase adjustment circuit.

Fig. 8 shows a part of a block diagram of an MMG variant in which the proposed method for identifying the phase shift of the secondary oscillations channel signal relative to the signal of the primary oscillations channel movable mass displacement transducer in the MMG and for adjusting the phase shift is used. A signal generated thereby is used in the MMG for generating the force (torque) feedback. In Fig. 8 the elements are connected in the following way:

The input of the first (element 69) and second (element 70) demodulators are united and connected to the output of the capacitive secondary oscillations axis MM displacement transducer. The outputs of these demodulators are connected to the inputs of the first and the second modulators (elements 73,

77, correspondingly) via the first and the second amplifying elements (elements 71, 72 correspondingly) , while their outputs are connected to the inputs of the summing device 77. The reference signal inputs of the same demodulators and modulators are connected to the outputs of the same phase shifting circuits via controllable phase shifting circuits (the first circuit 75 and the second circuit 76 correspondingly) . The inputs of these phase shifting circuits are connected to the output of the capacitive primary oscillations axis MM displacement transducer via the controllable phase shifting circuit 78. The control input of the phase shifting circuit 78 is connected via the integrator 80 and the third demodulator 79 to the voltage B(t) source and to the second output of the demodulator 70. The block diagram of Fig. 8 may be used in the MMG shown in Fig. 6 if it substitutes the elements 65-67. In this case the MMG is a compensation-type MMG. A compensation of the quadrature and torques caused by the Coriolis acceleration (by the channels with demodulators 69 and 70 correspondingly) occurs provided that the phase shifting circuit causes a 90° shift while the circuit 76 causes a 0° shift. In the device of Fig. 8 the phase adjustment is performed in the same manner as in the device shown in Fig . 7.

In Fig. 9 the elements are connected in the following way: For a more convenient representation of the electric elements the general electrode of all capacitive displacement and torque transducers of (MM 15) is shown partitioned.

Resistors 87-92 are connected between the output and the inverting input of the operational amplifiers (OA) 81-86 correspondingly. The input of the OA 81 is connected to electrode 16, input of the OA 82 is connected to the diametrically arranged electrode. The outputs of the OA 81, 82 via the differentiating amplifier 105 are connected to the input of the demodulator 93; another input thereof is connected to the voltage source 33. The output of the demodulator 93 is connected to the inputs of the demodulators 94, 95. The inputs of the differentiating amplifier 105a are connected to the stator of the comb motor. The outputs of the OA 84, 85 are connected to the electrodes arranged above the tooth area of the MM on one side of the MMG sensitivity axis, while the outputs of the OA 86 are connected to another pair arranged on the other side of the MMG sensitivity axis. Via the resistors 108, 109, the source 103 of the DC voltage is connected to the inputs of the OA 84, 85 correspondingly. The DC voltage source 104 is connected via the resistor 111 to the input of OA 86. The output of the differentiating amplifier 105a is connected to the input of demodulator 94 and the input of the phase shifting circuit 99, which is connected to the input of element 95. The AC voltage source 113 is connected to the input OA 86. Resistors 106, 107, 110, 112 are connected to the inputs of OA 83-86, correspondingly. The outputs of demodulators 94-96 are connected to the input of the low- frequency filter (LFF) 114 and to the input of element 96, to the input of the integrator 98, to the input of the integrator 97. The outputs of integrators 97, 98 are connected to resistors 106, 112, correspondingly. The output of element 95 is connected to the resistor 107 via the sequentially connected element 115 with a variable transmission coefficient, differentiating element 101 and inverting element 102. In the MMG of Fig. 9 the suspension resonant frequency self -adjustment circuit is formed at the elements 81, 82, 105, 93, 94, 96, 97, 83. These elements operate in the following way. The amplifiers 81, 82, 105 and the demodulator 93 form the "capacity-voltage" converter which forms a secondary oscillations axis MM displacement transducer with the electrodes connected to the inputs of the OA 81, 82. The demodulators 94, 96 extract the signal at the frequency of the source 100 forming the test action on the MM if the resonant frequencies of the suspensions do not match. In this case the output voltage of the integrator changes while the voltages at the in-phase OA 81, 82 change. Accordingly, the voltage at the inverting inputs of these OA and at the electrodes connected to them changes, which leads to changes in the resonant frequencies. Differentiating amplifier 105a may be formed similarly to the circuit at the elements 81, 82, 105 and 93; together with the connected stators it forms a primary oscillations axis MM displacement transducer. Due to self -adjustment of the resonant frequency, the signal of the output of demodulator 95 is proportional to the amplitude of the MM oscillations with the phase of the quadrature. The average component of these oscillations is suppressed by the output signal of integrator 98, which passes to the electrodes arranged above the comb section of the MM. The negative feedback via elements 101 and 115 allows to modify the transmission coefficient of the "Coriolis acceleration - voltage" converter at the output of element 94 (which is the MMG) by modification of transmission coefficient of the element in the circuit of the negative feedback. It should be noted that a stable transmission coefficient remains the same only if the system for self- adjustment of the frequency operates in case the MMG operates in the mode with the close frequencies. In Fig. 10 the elements are connected in the following way:

The inputs of the multiplier 116 are united and connected to the one input of the multiplier 117, output of the element 116 is connected to the capacitor 119 and the second input of the element 117 via the resistor 118, and its output is connected to the input of the element 101.

The elements 118, 119 form an LFF which smoothes the output signal of element 116, which is proportional to the square of the output signal of the MMG. The transmission coefficient of the feedback element in the MMG of Fig. 9 with such form of the element 115 depends on the value of measured angular speed Ω. The lower is the value, the weaker is the feedback signal. Hence, in case of low Ω values the MMG operates with a higher Q factor value, which allows to enhance the resolution of the MMG. MMG scale factor changes monitoring may be performed by measuring the signal at the output of element 116.

It should be noted that the element with a variable transmission coefficient may be realized by other means. In particular, it may be provided at the threshold of the element or by means of elements, which have a transmission coefficient changing depending on the input coefficient according to the table of values .

In Fig. 11 the indicator 120 is connected to the output of element 94 and source 100.

In case all MMG circuits are operable, the voltage at the output of demodulator 94 has a component, which is proportional to the test voltage. Comparing these voltages allows to test correct operation of the MMG.

To test the correct operation of the MMG, signals of the integrators 97, 98 may be used, their output signal being determined by initial off-tuning of the resonant frequencies and the level of the quadrature. These values may be categorized for each model of the micromechanical sensing element. In case of correct operation of the MMG, the comparison of current signal values from the outputs of the integrators to categorized values should stay within a defined range.

List of reference numerals

1 - primary oscillations channel of the MMG;

2 - micromechanical component of the secondary oscillations channel of the MMG; 3 - element with a coefficient (K₁) showing connection between the rate of primary oscillations axis MM displacement and force or torque affecting the MM by angular rate Ω along the axis of the MMG sensitivity;

4 - element with a coefficient (K₂) of transformation of primary oscillations axis MM displacement into the force or torque affecting the MM (so-called quadrature) ;

5 - multiplier;

6 - summer of the forces (torques) affecting the MM;

7 - secondary oscillations axis MM displacement transducer; 8 - demodulator;

9 - electric signal transformation unit;

10 - electrostatic force or torque transducer;

11 - test action on the MM;

12 - effect on the MM associated with a Coriolis acceleration by rotation of the MMG with angular rate Ω;

13 - modification of the test action amplitude on the MM;

14 - Ω modification;

15 - MM;

16 - electrode mounted above the MM; 17, 17a - electrodes arranged above the tooth area of the MM to the left of the Y axis;

18, 18a - tooth areas of the MM below the respective electrodes 17, 17a;

19 - tooth area of the MM; 20, 20a - electrodes arranged above the tooth area of the MM to the right of the Y axis;

21 - AC voltage source,-

22 - AC voltage source,-

23 - support; 24, 25 - stator of the capacitive primary oscillations axis MM displacement transducer;

24a, 25a - stators of the capacitive primary oscilliations axis MM displacement transducer arranged symmetrically to the stators 24, 25 relatively to the axis Y;

26, 27 - stator of the capacitive torque transducer producing a torque around the primary oscillations axis,-

26a, 27a - stators of the capacitive torque transducer producing a torque around the primary oscillations axis arranged symmetrically to the stators 26, 27 relative to the axis Y;

28, 29 - a pair of power electrodes arranged along the secondary oscillations axis;

30, 31 - a pair of electrodes of the capacitive secondary oscilliations axis MM position transducer; 32 - first 90° phase shift device for the electric signal; 33 - first AC voltage source;

34, 35 - first and second differential amplifiers; 36-38, 41, 47 - first, second, third, forth and fifth demodulators, respectively; 39 - second 90° phase shift device for the electric signal; 40 - phase shift device for the electric signal; 42, 48 - first and second integrators; 43 - second AC voltage source; 44, 49 - first and second summing devices; 45 - modulator;

46 - differentiating device;

50, 51 - first and second amplifiers;

52 - MM;

53 - electrode arranged below the MM 52; 54 - teeth arranged on the lateral surface of the MM 52;

55 - stator of the comb capacitive transducer;

56 - stator teeth;

57 - supports;

58 - torsions; 59 - group of electrodes arranged below MM lateral surface; 59 - group of electrodes arranged below MM lateral surface in between the teeth 54 ;

61, 62 - first and second differential amplifiers; 63-64 - first, second, third, forth and fifth demodulators respectively;

67 - integrator;

68 - controllable phase shift device for the electric signal;

69, 70 - first and second demodulators; 71, 72 - first and second modulators;

73, 74 - first and second amplifying elements, correspondingly;

75, 76 - first and second phase shifting circuits;

77 - summing device; 78 - phase shifting circuit;

79 - third demodulator;

80- - integrator;

81-86 - operational amplifiers (OA) ;

87-92 - resistors; 93-96 - demodulators;

97, 98 - integrators;

99- - phase-shifting circuit;

100 - AC voltage source;

101 - differentiating element; 102 - inverting element;

103, 104 - DC voltage source; 105, 105a - differential amplifiers; 106-113 - resistors; 114 - low-frequency filter (LFF) ; 115 - element with a variable transmission coefficient; 116, 117 - multipliers;

118 - resistor;

119 - capacitor;

120 - indicator.

Claims

1. A method for generating a test action to a movable mass of a micromechanical gyroscope, comprising modifying voltages at electrodes arranged along the secondary oscillations axis of the movable mass (MM) , a displacement of said movable mass along the axis of primary oscillations Y changing in time (t) according to the following expression: Y (t ) ≡sin (cύit) , wherein ω_x is an angular frequency,

characterized in that the voltage on one or more electrodes is modified so that the harmonious component A(t) with frequency G)i having value

according to the following expression:

A(t)^≡ B(t)sⁱn(αy)_{^ wnere}i_n an amplitude B(t)≠_Const, C(α,γ(t)) is a capacity between the movable mass and the electrode where the voltage is being varied, α denotes MM displacements along the secondary oscillations axis, respectively.

2. The method according to claim 1, characterized in that, when, in case of oscillations of the movable mass along a primary oscillations axis, an overlapping area between the movable mass and one or more electrodes changes, the voltage at said electrodes is modified at a frequency less than a primary oscillation frequency.

3. The method of claim 1, characterized in that when, in case of oscillations of the movable mass along the axis of the primary oscillations, an overlapping area between the movable mass and one or more electrodes does not change, the voltage at said electrodes is modified at a frequency which is equal to the frequency of the primary oscillations, in phase with the primary oscillations of the movable mass, thereby modifying the amplitude of said voltages.

4. An electrode structure of a RR-type micromechanical gyroscope, comprising a movable mass having a form of sectors arranged symmetrically relative to sensitivity axes of the micromechanical gyroscope and secondary oscillations of the movable mass, and electrodes arranged above or below the movable mass, characterized in that a part of said electrodes being arranged above or below lateral borders of the sectors.

5. The electrode structure of claim 4, characterized in that the movable mass is provided with openings oriented perpendicularly to the directions of the primary oscillations, and a part of the electrodes is arranged above or below the edges of the openings .

6. An electrode structure of an LL-type micromechanical gyroscope, comprising a movable mass having a form of a rectangle, the first pair of sides of said rectangle being perpendicular to the direction of the primary oscillations and the second pair of the sides of said rectangle being parallel to said direction; and electrodes being arranged above and below the movable mass, characterized in that a part of said electrodes being arranged above or below the lateral edges of one or both pairs of said sides.

7. The electrode structure of claim 6, characterized in that the movable mass is provided with openings oriented perpendicularly to the directions of the primary oscillations, and a part of the electrodes is arranged above or below the edges of said openings.

8. A method for adjusting a resonant frequency of a suspension of a movable mass along a secondary oscillations axis, comprising: extracting a component of a signal of a secondary- oscillations axis movable mass displacement transducer, modifying the voltages at the electrodes arranged along the axis of the secondary oscillations depending on the extracted component , characterized in that the extracted component being proportional to amplitude B(t) .

9. The method of claim 8, characterized in that the step of extracting of the component being proportional to the amplitude B(t) comprises sequential demodulation of the signal of the secondary oscillations axis movable mass displacement transducer first with a reference signal that is in phase with the primary movable mass oscillations and then with a reference signal that is proportional to B(t) .

10. An RR- type micromechanical gyroscope, comprising: a movable mass in a form of sectors, arranged symmetrically relative to the axes of sensitivity of the micromechanical gyroscope and secondary oscillations of the movable mass, the lateral surfaces of these sectors comprising teeth, three pairs of electrodes arranged above the movable mass and also having a form of sectors, the first pair of electrodes being arranged above the tooth areas of the movable mass that are arranged on one side relative to the sensitivity axis of the micromechanical gyroscope, the second pair being arranged symmetrically relative to said axis, and the third pair of electrodes being arranged on said axis, the electrodes of each pair being arranged symmetrically to the axis of secondary oscillations; stators mounted on the base and having teeth, forming together with the teeth of the movable mass a comb electrode structure; a suspension in a form of torsions, by means of which the movable mass is suspended to the support arranged on the base; a primary oscillation excitation device disposed between the stators and comprising a first movable mass displacement transducer and an electric signal transformation device; a second movable mass displacement transducer in a form of a differential transresistive amplifier with inputs connected to the first pair of electrodes; a DC voltage source connected to the second pair of electrodes, a first demodulator with an input connected to the output of the transresistive amplifier and a reference signal input connected to the output of the first movable mass displacement transducer, characterized in that the gyroscope comprises : an AC voltage source connected in series with the DC potential source; a second demodulator with an input connected to the output of the first demodulator and a reference signal input connected to the connected AC voltage source,- and an integrator with an input connected to the output of the second demodulator and the output connected to the third pair of electrodes.

11. An RR-type micromechanical gyroscope, comprising: a movable mass in a form of sectors arranged symmetrically relative to the axes of sensitivity of the micromechanical gyroscope and secondary oscillations of the movable mass, the lateral surfaces of these sectors comprising teeth; two pairs of electrodes, the electrodes in each pair being arranged symmetrically relative to said axes above the movable mass; the electrodes of the first pair being electrodes of a capacitive secondary oscillations axis movable mass displacement transducer while the electrodes of the second pair being electrodes of a capacitive torque motor; stators mounted on the base and having teeth, forming a comb electrode structure with the teeth of the movable mass; a suspension in a form of torsions, by means of which the movable mass is suspended to the support arranged on the base,- a primary oscillation excitation device disposed between the stators and comprising the first movable mass displacement transducer and an electric signal transformation device; a second movable mass displacement transducer in a form of a differential amplifier with inputs connected to the electrode of the first pair; a first demodulator with an input connected to the output of the second movable mass displacement transducer and reference signal input connected to the output of the first movable mass displacement transducer; amplifiers with outputs connected to the electrodes of a torque transducer, characterized by having an AC voltage source, a second and a third demodulator, and a modulator, the outputs of the second and the third demodulator being connected to an output of the summing device and with the same inputs of the amplifiers correspondingly via a first and a second integrator; the AC voltage source being connected to the modulator via the summing device, the output of said modulator being connected to the opposite inputs of the amplifiers, the reference signal inputs of the second and the third demodulators and of the modulator are coupled, correspondingly, with the output of the second movable mass displacement transducer via a 90° phase shift device, with the AC voltage source and with the output of the second movable mass displacement transducer via the phase shifter.

12. A method for identifying a phase shift of a signal in the secondary oscillations channel relative to a signal of a primary oscillations channel movable mass displacement transducer in an MMG comprising at least one electrode arranged non-coaxially to the direction of the primary oscillations of the movable mass, and a B(t) voltage source connected to said electrode, the method comprising: primary synchronous detecting of the signal of the secondary oscillations channel movable mass displacement transducer by means of a first reference signal, a signal of a primary oscillations channel movable mass displacement transducer being used as a first reference signal, characterized in that the method further comprises secondary synchronous detecting, the secondary synchronous detecting being performed by means of a second reference signal, the voltage B(t) being used as said second reference signal; and modifying the phase of the first reference signal until the average value of the signal equals 0 after the secondary synchronous detecting.

13. A micromechanical gyroscope, comprising: a movable mass in a form of sectors arranged symmetrically relative to the axes of sensitivity of the micromechanical gyroscope and secondary oscillations of the movable mass; a resonant suspension of the movable mass in a form of torsions, by means of which the movable mass is suspended to the support mounted on the base; a comb electrode structure; a primary oscillation excitation device with inputs and outputs connected to the corresponding electrodes of the comb structure; electrodes arranged along the axis of the secondary oscillations, said electrodes having a form of sectors, wherein at least one of the electrodes is arranged above the lateral border of one of the sectors ; a first capacitive primary oscillations axis movable mass displacement transducer; a second secondary oscillations axis movable mass displacement transducer, wherein the inputs of the first and second demodulators are connected to the output of the second movable mass displacement transducer, the outputs of said demodulators being connected, correspondingly, to the inputs of the first and second modulators via amplifying elements, the reference signal inputs of the same modulators and demodulators are connected to the output of the first movable mass displacement transducer via the first and second phase-shifting networks, the outputs of the modulators being connected to at least one of the electrodes arranged along the axis of the secondary oscillations via a summing device, characterized in that the gyroscope comprises an AC voltage source with the output connected to the electrode arranged above the lateral border of one of the sectors,- a controllable third phase- shifting network; a third demodulator and integrator connected in series, wherein the inputs of the third demodulator are connected to the output of the first demodulator and the output of the connected AC voltage source, the output of the integrator is connected to the control input of the third phase-shifting network, which is connected between the output of the first movable mass displacement transducer and the inputs of the first and second phase- shifting network.

14. A micromechanical gyroscope with an automatic frequency adjustment circuit and a damping feedback in the secondary oscillations channel, which is realized in the form of a differentiating element disposed between the output of secondary oscillations axis movable mass displacement transducer and the electrodes arranged on said axis, characterized in that it further comprises a variable gain device, the device is connected in series with said differentiating element.

15. The micromechanical gyroscope of claim 14, characterized in that the gyroscope comprises an input value modulus average extraction device, an output of said device being connected to the transmission coefficient modification input and an input of said device being connected to the input of the variable transmission coefficient device.

16. A method for continuous testing of correct operation of a micromechanical gyroscope, comprising: determining a response to a test signal, comparing the response of the micromechanical gyroscope to the test signal and the reference signal, characterized in that the step of determining the response to the test signal comprises primary demodulating of the output signal of a secondary oscillations axis movable mass displacement transducer using the reference signal on the frequency of the primary oscillations and secondary demodulating using the reference signal proportional to B(t) .