RU2301970C1 - Micro-mechanical vibration gyroscope - Google Patents

Abstract

FIELD: navigation.

SUBSTANCE: micro-mechanical vibration gyroscope comprises two pairs of electrodes arranged along the axis of secondary vibration, device for exciting primary vibration connected between the capacitive pickups and arranged along the axis of the primary vibration, electrodes of comb motor, amplifier and differential link connected in series between the pairs of the electrodes arranged along the axis of secondary vibration, and phase-rotating link, demodulator, and low-frequency filter connected in series. One pair of the electrodes is a measuring one, and the other is load-bearing. The input of the phase-rotating link is connected with the output of the capacitive pickup along the axis of the primary vibration. The device for suppressing quadrature is connecter between the differential link and input of demodulator. The second input of the device is connected with the output of the capacitive pickup along the axis of the primary vibration.

EFFECT: enhanced sensitivity and precision.

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Description

The proposed device relates to devices that measure angular velocity, in particular to micromechanical gyroscopes (MMG).

Known micromechanical gyroscopes and devices for converting electrical signals into them (see US patent No. 6571630, 6715353, 5992233, 6370937, 5672949). The output signal along the output coordinate of the gyroscope can contain, in addition to the useful signal, a quadrature interference (the so-called component of the signal whose phase is shifted 90 ° with respect to the useful component). Under the action of the force due to the presence of quadrature interference, which can exceed the maximum useful signal, the amplitude of the rotor oscillations can approach the maximum permissible values, which are determined by the gap between the rotor and the base, which ultimately leads to a decrease in the dynamic range of MMG operation. Different methods of suppressing quadrature interference are used in technology: so in the gyroscope according to US Pat. US No. 6715353 use parametric resonance in the device according to US Pat. USA No. 6067858 (figa, 18) form a constant voltage on special electrodes, in an article by Andreeva T.A., Nekrasov Y.A. "Adaptive quadrature interference suppression system in a micromechanical gyroscope." - Gyroscopy and navigation, 2005, No. 3 (50), p. 79, St. Petersburg: Central Research Institute "Electropribor"; and on the website: http://www.elektropribor.spb.ru/cnf/kmu7/dokl/s3-7.zip the compensation method is used. Another way to reduce the influence of quadrature noise on the dynamic range of MMG operation is to introduce negative feedback on the movement of the moving mass along the axis of secondary vibrations (V.Ya.Raspopov Micromechanical devices, Fig.5.58). An article by Woon-Tahk Sung et al. “H _∞ Controller Design of MEMS Gyroscope and Its Performance Test” (No. 0-7803-8416-4 / 04 / $ 20.00 © 2004 IEEE) describes an MMG including a movable mechanical element, measuring electrodes to which the input of the proportional-integral-differential (PID) controller is connected (see Besekersky VA Dynamic synthesis of automatic control systems. - M., Nauka, 1970, p. 299), and power electrodes on which voltage is generated from the output of the PID controller and the rotor on a resonant suspension, forming a system in which the forces acting on the rotor are measured and stabilizing his position. In the case when there is no quadrature interference in the MMG, the generated voltage is proportional to the Coriolis acceleration. In the presence of quadrature interference, a component proportional to this interference will be present in the voltage, which is a disadvantage of this MMG, as a result of which the accuracy of the gyroscope deteriorates. Thus, the described MMG can be used only in the absence of quadrature interference.

MMG are known, described in the article by Andreeva T.A., Nekrasov Y.A. Adaptive quadrature interference suppression system in a micromechanical gyroscope. - Gyroscopy and navigation, 2005, No. 3 (50), p. 79, St. Petersburg: Central Research Institute "Electropribor"; and on the website: http://www.elektropribor.spb.ru/cnf/kmu7/dokl/s3-7.zip, in which, at a low level of quadrature interference, the rotor moves under the influence of the Coriolis force and the force due to the presence of quadrature interference. These movements, measured by capacitive sensors, contain information about both the useful component and the quadrature interference. The latter is suppressed in the described MMG in the channel for processing output signals due to the formation of a voltage that compensates for interference. This MMG has a low sensitivity as a result of working at a low gain, since an increase in the coefficient in this MMG leads to large nonlinearity.

The device described in Woon-Tahk Sung, Jang Gyu Lee's article “H _∞ Controller Design of MEMS Gyroscope and Its Performance Test” (No. 0-7803-8416-4 / 04 / $ 20.00 © 2004) is the closest to the device and selected as a prototype.

The problem to which the invention is directed is to increase the sensitivity, linearity and accuracy of MMG.

The solution to this problem is achieved by the fact that a serially connected amplifier and a differentiating element are inserted into the micromechanical gyroscope, connected between the pairs of electrodes along the secondary oscillation axis, a phase-shifting link and a demodulator are connected in series, while the input of the phase-shifting link is connected to the output of the capacitive sensor along the primary oscillation axis characterized in that between the output of the differentiating link and the input of the demodulator, a quadrature suppression device is introduced, the second input which is connected to the output of the capacitive sensor along the axis of the primary oscillations.

In addition, the solution to this problem is achieved by the fact that the quadrature suppression device is made in the form of series-connected first multiplier, integrator, second multiplier, demodulator, low-pass filter, adder and amplifier, the first adder input is connected to the output of the differentiating link, the second input to the output the second multiplier, the second inputs of the multipliers are connected to the output of the capacitive sensor along the axis of the primary oscillations. The main advantage of the invention is due to the claimed combination of features.

The claimed device is illustrated by drawings.

Figure 1 shows a block diagram of the proposed device.

In figure 1, the following notation:

1 - a sensitive element of a micromechanical gyroscope;

2 - measuring electrodes;

3 - power electrodes;

5, 7 - capacitive sensors;

6 - phase shifter;

8 - amplifier;

9 - differentiating link;

10 is a quadrature suppression device;

11 - demodulator.

12 - low pass filter;

13 - adder;

14 - amplifier;

15, 17 - the second and first multipliers, respectively.

16 - integrator.

Figure 2 shows the graphs of the signals in the proposed device.

In figure 2, the following notation:

And - the change in time of the signal at the output of the element 16 with a jump at the input of the element 13 of the signal, with quadrature noise and useful component;

B - signal at the output of element 15.

The sensing element 1 consists of a movable element 2, measuring electrodes along the axes of primary and secondary vibrations 3 and power electrodes 4. Capacitive sensors 5 and 7 are connected to the measuring electrodes 3, which convert the capacitance to voltage. An amplifier 8 and a differentiating element 9 are connected in series to the output of the capacitive sensor 7 along the axis of secondary vibrations. The output of the differentiating element is connected to power electrodes 4 of CE 1 and to the input of the squelch suppression device 10, the output of which is connected to the input of the demodulator 11. The second input of the device 10 is connected to the input of the phase shifter 6 and the output of the capacitive sensor 5 along the primary axis. The output of the phase shifter is connected to the second input of the demodulator 11, the output of which is connected to the input of the low-pass filter 12.

The device operates as follows.

Under the influence of the Coriolis force and forces arising due to the rigidity of the torsion, the rotor begins to deviate. The signal converted to voltage using a capacitive sensor 7, proportional to the rotor deviations, is fed through an amplifier 8 to a differentiating link 9, which ensures the stability of a closed system. The signal from the output of the differentiating link 9 is fed to the power electrodes 3. With deep feedback, the rotor will be stationary. The signal at the output of the differentiating link 9 contains useful and quadrature components. It arrives at the squelch suppression device 10, where it is amplified by the element 14 and fed to the input of the first multiplier 17. Since the voltage of the same frequency as the first input is supplied to the second input of the multiplier 17, the element 17 performs phase-sensitive detection of the input signal and isolates the signal in phase with the signal coming from the amplifier 14, i.e. quadrature interference. The extracted signal is integrated by element 16 and modulates the signal from the output of the phase shifter using the second multiplier 15. The output signal of the second multiplier 15 is added by the adder 13 to the signal from the output of the differentiating link 9. Since the quadrature noise and the output signal of the second multiplier 15 are in antiphase, the quadrature interference is suppressed . The output signal from the quadrature suppression device with the already compensated quadrature noise is supplied to the demodulator 11, where it is multiplied with the signal shifted by the phase shifter 6 by 90 ° with respect to the voltage at the output of the capacitive sensor along the axis of the primary oscillations, i.e. with common mode signal. Then the signal containing only the useful component is filtered on the low-pass filter 12. Thus, the output is a voltage containing only information about the angular velocity of the base MMG.

The signals shown in figure 2, obtained by modeling the proposed device. The signal at the output of the integrator 16 changes until the signal from the output of the element 15 is equal to the quadrature noise at the output of the differentiating link 9. Until the quadrature interference is compensated, the useful component of the signal is practically not allocated.

Claims (1)

A vibration-type micromechanical gyroscope containing a movable mechanical element, two pairs of electrodes along the axis of secondary vibrations, one of which is a measuring one, the other is a power one, a serially connected amplifier and a differentiating element, connected between pairs of electrodes along the axis of secondary vibrations, a series-connected phase-shifting link, a demodulator and a low-pass filter, while the input of the phase-shifting link is connected to the output of the capacitive sensor along the axis of the primary oscillations, characterized in that between the output of the differentiating link and the input of the demodulator a quadrature suppression device is introduced, made in the form of a series-connected first multiplier, an integrator and a second multiplier, as well as an adder, the first input of which is connected to the output of the differentiating link, the second input - with the output of the second multiplier, and an amplifier, which amplifies the output signal of the differentiating link and the signal from the output of which is fed to the input of the first multiplier, the second inputs of the multipliers are connected to the output of the capacitive sensor along the axis primary fluctuations.

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