RU2282152C1 - Device for converting signal from micromechanical vibration gyroscope - Google Patents

Abstract

FIELD: measuring technique.

SUBSTANCE: device comprises movable member, comb motor, capacitive pickups of movements of the movable mechanical member along the axis of the primary oscillations and output axis. The device has phase shifter made of a control device whose input is connected to the output of the capacitive pickup along the axis of the primary oscillations and demodulator whose first input is connected with the output of the capacitive pickup along the output axis and output is connected with the output of the low-frequency filter, and integrator. The input of the control of the phase shifter is connected with the output of the integrator whose input is connected with the output of the demodulator. The device can be additionally provided with summing amplifier, two multipliers and second phase shifter whose inputs are connected with the inputs of the first phase shifter and output, with the inputs of multipliers.

EFFECT: enhanced precision.

3 cl, 4 dwg

Description

The invention relates to the field of measuring equipment, in particular to micromechanical gyroscopes (MMG) and signal conversion devices in them.

Known micromechanical gyroscopes and devices for converting electrical signals into them (see US patent No. 6571630, 6715353, 5992233, 6370937, 5672949). The output signal of the sensor along the output coordinate of the gyroscope may contain, in addition to the useful interference signal: quadrature interference (the so-called signal component whose phase is shifted 90 ° with respect to the useful component) and components from the power signal. Different methods of suppressing quadrature interference are used in the technique: for example, in the gyroscope of US Pat. US No. 6715353 use parametric resonance, in devices according to US Pat. US No. 6571630, 5992233, 6370937 generate voltage on special electrodes. The disadvantage of these devices is the design complexity due to the need to introduce additional electrodes and control loops.

The device for converting electrical signals MMG shown in Fig.8 pat. US No. 6626039, is the closest to the proposed device and is selected as a prototype.

MMG vibration type according to US Pat. USA No. 6626039, includes a movable mechanical element (a rotor on a torsion suspension), a comb engine (in Fig.8 its electrodes are denoted With _t1 , C _t2 ) and capacitive sensors for moving the rotor along the axis of primary oscillations and the output axis (in Fig. 8, the electrodes forming the corresponding sensors with electronic nodes are designated C _s1 , C _s2 and C _d1 , C _d2 ). The capacitive sensor for moving the rotor along the axis of primary vibrations includes amplifiers 56, 57, a demodulator 62, and a low-pass filter (LPF) 63. A capacitive sensor for moving the rotor along the output axis is similarly constructed (on elements 58, 59, 64, and 65). To excite these sensors, a high-frequency source with antiphase outputs on the elements 51, 52 is used, the output signal of which is supplied to the demodulators 62, 64. The output signals of these capacitive sensors are then fed to the input of the MMG signal conversion device, which contains a phase-shifting device (element 67) and a demodulator 66 with a low-pass filter 68. At the input of element 66 from a capacitive sensor for moving the rotor along the output axis, a signal Uin is received containing the useful component Uп and the quadrature noise Uкв, which coincides in phase with a signal from the output of capacitive sensors for moving the rotor along the axis of the primary oscillations.

Uin (t) = Uп (t) + Uкв (t) = UпSin (ωt) + Uкв Cos (ωt) (1)

The introduced phase shift φ of element 67 is ideally 90 °, which provides complete suppression of the quadrature interference Uqu.

However, if the angle deviates from 90 ° by the angle α, we obtain that the output signal of the demodulator is 66 Uout (t)

Uout (t) = Uin (t) Sin (ωt + α) (2)

At the output of the low-pass filter 68, after filtering the high-frequency components, the signal U ₆₈ will be determined by the expression

U ₆₈ = UпCos (α) + Uкв Sin (α) (3)

Note that the influence of the angle α is manifested in a change in the scale factor (first term) and a zero offset (second term in expression 3). Moreover, the influence of the angle α (for small α) on the scale factor is much smaller than on the zero offset even with the values of Uп, Uкв of the same order. And given that these values can differ by several orders of magnitude, we can conclude that one of the main reasons for the MMG zero drift is the instability of the introduced phase shift and the large value of the quadrature noise.

Note that the capacitive sensors MMG can be powered from a constant voltage source, as shown in US Pat. US No. 5672949 or in US Pat. USA No. 6253612 on fig.3d. In this case, the elements 51, 52 and 62-65 are not used, however, the composition of the electrical signal conversion device remains the same.

The invention solves the problem of improving the accuracy of MMG.

The problem in the proposed device is solved by the fact that an integrator is introduced into the signal conversion device of the vibration-type micromechanical gyroscope, and the phase-shifting device is designed as a controlled device, while the control input is connected to the integrator output, the input of which is connected to the demodulator output.

In addition, the task is solved in that a summing amplifier is introduced into the signal conversion device of the vibration-type micromechanical gyroscope, the first input of which is connected to the output of the capacitive motion sensor of the moving mechanical element along the output axis, the first multiplier, the first input of which is connected to the output of the introduced summing amplifier, an additional amplifier, the input of which is connected to the output of the first multiplier, a second multiplier, the first input of which is connected to the output of the additional amplifier, the output of the second multiplier is connected to the second input of the summing amplifier, and a second controlled phase shifter, while the second inputs of the introduced multipliers are connected to the output of the second phase shifter, the inputs of which are connected to the inputs of the same phase shifter.

In addition, the problem is solved in that the phase shifter is made in the form of series-connected low-pass filter of the multiplier and the adder, while the second input of the adder is connected to the input of the low-pass filter, and the second input of the multiplier is the control input of the phase shifter.

The main advantage of the invention (reducing the effect on the accuracy of MMG introduced by the output channel of the phase shift and quadrature interference) is due to the claimed combination of features.

The claimed device is illustrated by drawings.

Figure 1 shows the block diagram of the MMG with the proposed device.

In figure 1, the following notation:

1 - MMG

2, 3 - capacitance of the rotor displacement sensor along the axis of primary vibrations

4, 5 - capacitance of the rotor displacement sensor along the output axis

6, 7 - DC voltage sources

8, 9 - amplifiers with inverting input

10, 11 - resistors

12, 13 - capacitors

14 - demodulator

15 - phase shifter

16 - low-pass filter (low-pass filter)

17 - integrator

Figure 2 shows the block diagram of MMG with an embodiment of the proposed device.

In figure 2 (elements 1-17 are denoted in the same way as in figure 1) the following notation:

1 - MMG

2, 3 - capacitance of the rotor displacement sensor along the axis of primary vibrations

4, 5 - capacitance of the rotor displacement sensor along the output axis

6, 7 - DC voltage sources

8, 9 - amplifiers with inverting input

10, 11 - resistors

12, 13 - capacitors

14 - demodulator

15 - phase shifter

16 - low-pass filter (low-pass filter)

17-integrator

18 - summing amplifier

19 - node summation

20 - amplifier

21, 24 - multipliers

22 - additional amplifier

23 - controlled phase shifter

Figure 3 shows a block diagram of an embodiment of a controlled phase shifter.

In figure 3, the following notation:

25 - amplifier

26 - multipliers

27 - adder

28, 29 - resistors

30 - capacitor

In figure 4. a block diagram of MMG with an embodiment of the proposed device.

Elements 1-24 in figure 4 have the same designations as in figure 2.

31 is a storage device.

In MMG 1, the capacities of the rotor displacement sensor along the axis of primary vibrations 2,3 are formed by combs located on the moving mass or rotor and the stators combs, and the capacities of the rotor displacement sensor along the output axis 4, 5 are formed by the moving mass or rotor and the corresponding electrodes located on the base . To the stators and electrodes located on the base, the leads of the power supplies 6, 7 are connected. The common leads of the capacities 2, 3 and 4, 5 are connected respectively to the inverting inputs of the amplifiers 8, 9, between the outputs of which and the inputs are connected, respectively, resistors 10, 11 and capacitors 12, 13. Elements 2, 3, 8, 10, 12 form a capacitive sensor for moving the movable mechanical element along the axis of primary vibrations, and elements 4, 5, 9, 11, 13 form a capacitive sensor for moving the movable mechanical element along the axis of the primary axis.

The proposed device comprises a demodulator 14 and a phase shifter 15. The input of the low-pass filter 16 is connected to the output of the demodulator 14. The phase shifter 15 is designed as controlled, i.e. the phase shift introduced by it can be changed by applying an electrical signal to its input, called the control input. Between the output of the demodulator 14 and the control input of the device 15, an integrator 17 is turned on.

The device operates as follows.

The signal at the output of amplifier 9 (see Fig. 1) contains the useful and quadrature components (see expression 1). This signal is converted by the demodulator 14 into a signal proportional to the angular velocity around the sensitivity axis of the MMG and the value of Uqu Sin (α) (see expression (3)). In the case when the introduced phase shift in the output channel is different from zero or, more precisely, from the introduced phase shift in the primary oscillation channel, a constant electric signal appears in the proposed device at the input of the integrator 17, which causes a change in the phase shift introduced by the device 15, which the queue will lead to a decrease in the component due to quadrature interference. Moreover, due to the fact that changes in the output signal occur until the input signal becomes equal to zero, the value of α in the proposed device is automatically reduced to zero. In order that in the proposed device the measured angular velocity does not lead to a change in the angle α, the integration time constant of the integrator 17 should be sufficiently large. For example, if the MMG is designed to measure the rate of change of the pitching angles of a small vessel, the integrator should have a transmission coefficient equal to unity at frequencies of the order of 0.001 Hz. In this case, the variable component at the input of the integrator 17 will be substantially suppressed by this device and will not lead to a change in the phase of the output signal of the phase shifter.

In the device of FIG. 2, between the output of amplifier 9 and the input of demodulator 14, a summing amplifier 18 is connected, which is formed by series-connected summing unit 19 and amplifier 20. Serially connected multiplier 21, amplifier 22 and multiplier 24 are connected between the output of amplifier 20 and the input of summing unit 19 A controlled phase-shifting device 23 is connected between the output of the amplifier 8 and the second inputs of the multipliers 21, 24, and its control input is connected to the output of the integrator 17.

The device in figure 2 works as follows. In the multiplier 21 operating as a synchronous detector, an input signal component in phase with the reference signal is extracted, i.e. with a signal at the output of the rotor displacement sensor along the axis of the primary vibrations. The extracted component of the amplifier 22 is amplified and filtered. Note that for filtering multiple harmonics, the amplifier must have a transfer function, like a low-pass filter. The constant component of the output signal of the amplifier 22 by the multiplier 24 is converted into a signal that is close in amplitude and opposite in phase to the quadrature noise at the output of the amplifier 9. Therefore, only the uncompensated component of the quadrature interference and the useful signal pass through the amplifier 20. Due to the fact that the interference level is reduced, it is possible to increase its gain, which improves the accuracy of MMG. Automatic adjustment of the phase shift by the angle α equal to the phase shift in the output channel due to the signal of the integrator 17 is provided in the proposed device in devices 15 and 23. This provides more accurate compensation for quadrature noise in the amplifier 18 and its suppression by the multiplier 14. Thanks to the automatic adjusting the phase shift in devices 15 and 23 in the MMG, you can choose the resonant frequencies of the channels close, which allows to increase the accuracy of MMG without the harmful effects of temperature on the accuracy of MMG due to changes in wearable phase shift in the output channel.

In the circuit of FIG. 3, an amplifier low-pass filter is formed on the amplifier 25 using resistors 28, 29 connected to its input and output and capacitor 30, introducing a phase shift in the output signal up to 90 °. The output of the amplifier through the multiplier 26 is connected to the input of the adder 27, the other input of which is connected to the resistor 28. The phase of the signal at the output of the adder 27 depends on the transmission coefficient of the multiplier 26. The latter is proportional to the voltage at the control input (Fig. 3 shows the output of Control). Thus, in the device of Fig. 3, a change in the phase shift of the output signal is achieved by changing the voltage at one of the inputs. The necessary constant phase shift can be achieved using known corrective links on passive elements. Note that, if it is necessary to maintain the amplitude of the output signal of the phase shifting device, the known automatic gain control circuit can be used or a phase locked loop can be used as a phase shifting device.

In the circuit of FIG. 4, a storage device 31, for example a sample-storage amplifier, is inserted between the output of the integrator and the inputs of the phase shifting devices 15, 23.

The device in FIG. 4 operates similarly to the device in FIG. 2 when the sample-storage amplifier is in sample mode. It is advisable to use this mode when the MMG is on an object that does not perform continuous circulation, or is stationary. The device 31, it is advisable to transfer to storage mode at the beginning of movement or circulation. In this case, the voltage at the output of the integrator 17, corresponding to the phase shift necessary for the maximum suppression of quadrature interference, will be saved. Repeated transitions to the sampling mode of the device 31 are possible with the corresponding state of the object with MMG installed on it.

The proposed device can be used with other types of capacitive sensors described in the literature (for example, in US Pat. No. 6253612, figure 3).

Claims (3)

1. A signal conversion device of a vibration-type micromechanical gyroscope, including a movable mechanical element, a comb engine and capacitive displacement sensors of a movable mechanical element along the axis of primary oscillations and an output axis, comprising a phase-shifting device whose input is connected to the output of the capacitive sensor along the axis of primary oscillations and a demodulator, the first input of which is connected to the output of the phase shifter, the second input is connected to the output of the capacitive sensor at the output B, and the output of the demodulator is connected to the input low-frequency filter, characterized in that it entered the integrator and fazovraschatelnoe device is configured as a controlled device, the control input coupled to the output of the integrator, which input is connected to the output of the demodulator. 2. The device according to claim 1, characterized in that a summing amplifier is introduced into it, the first input of which is connected to the output of the capacitive sensor for moving the movable mechanical element along the output axis, the first multiplier, the first input of which is connected to the output of the summing amplifier, an additional amplifier, an input which is connected to the output of the first multiplier, the second multiplier, the first input of which is connected to the output of the additional amplifier, the output of the second multiplier is connected to the second input of the summing amplifier, and the second control a removable phase-shifting device, while the second inputs of the introduced multipliers are connected to the output of the second phase-shifting device, the inputs of which are connected to the same inputs of the first phase-shifting device. 3. The device according to claim 1, characterized in that the phase shifter is made in the form of a series-connected low-pass filter, a multiplier and an adder, with the second input of the adder connected to the input of the low-pass filter, and the second input of the multiplier is a control input of the phase shifter.

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