RU2697031C1 - Micromechanical gyro control system - Google Patents

Abstract

FIELD: micromechanics.

SUBSTANCE: invention relates to micromechanics, particularly to micromechanical gyroscopes (MMG), and is intended for control and processing of MMG signals. Micromechanical gyroscope control system comprises signal conversion unit consisting of analogue-to-digital and digital-to-analogue converters and interacting with signal processing unit. Signal processing unit is made in the form of excitation unit and secondary oscillation processing unit, and signals conversion unit is equipped with amplifiers of output signals of digital-to-analogue converters receiving signals from excitation unit and secondary oscillation processing unit, and summators receiving analogue signals from amplifiers of output signals and excitation and processing units of secondary oscillations.

EFFECT: high accuracy and stability of the micromechanical gyroscope with reduced temperature effect, owing to tuning of the natural frequency of primary oscillations of the SE and tuning of the frequency of secondary oscillations to eliminate quadrature error, as well as simple implementation, adjustment and calibration of the system and obtaining a digital output signal, by implementing the control circuit in digital form.

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Description

The invention relates to the field of micromechanics, in particular to micromechanical gyroscopes (MMG), and is intended to control and process MMG signals.

A known gyroscope control system described in the invention under the title "Method for adjusting the resonant frequency of a suspension of a moving mass of a micromechanical gyroscope along the axis of secondary vibrations and a micromechanical gyroscope" [RF patent No. 2308682, IPC (2006.01) G01C 19/56, G01P 9/04, published 20.10 .2007], containing the signal processing unit.

The signal processing unit comprises a phase detector receiving input signals from a first current difference device that has passed through a phase shifting device and from a second current difference device, and a low-pass filter that receives an input signal from a phase detector. The output of the low-pass filter is the MMG output. The signal processing unit further comprises a second phase detector, an adder and an integrator included between the output of the second current difference extraction device and the output of the additional electrode.

The specified system allows to increase the accuracy of adjusting the resonant frequency of the suspension of the moving mass of the micromechanical gyroscope along the axis of secondary vibrations and to improve the accuracy of the micromechanical gyroscope.

The disadvantages of this system include:

- lack of adjustment of the resonant frequency along the axis of the primary oscillations;

- the need to use precision analog electronic circuits;

- the need for manual procedures for setting up and calibrating the device.

A known digital control system of a vibrating gyroscope [US patent No. 6276204, IPC ⁷ G01P 9/04, published 21.08.2001]. comprising a signal conversion unit consisting of analog-to-digital and digital-to-analog converters and interacting with a signal processing unit.

In the digital control system of the vibrating gyroscope, discretization tools are provided at selected time intervals of the output signals before moving to a signal processing unit including a variable frequency generator.

To reduce errors in the known system, the processing frequency is adjusted to the resonant frequency of the SE using a controlled variable frequency generator. The frequency of the generator is regulated in accordance with the resonant frequency of the SE based on the signals received by the digital processor from the primary oscillation sensor.

With a similar structural structure, this system has several disadvantages:

- instability of the frequency of primary oscillations and, accordingly, the frequency of the system;

- the lack of adjustment of the resonant frequency of the secondary oscillations to compensate for the quadrature error.

This technical solution is considered as the closest analogue, as the closest to the claimed invention.

The problem to which the invention is directed, is to create a micromechanical gyroscope control system with high accuracy and stability of a micromechanical gyroscope, as well as a low temperature effect.

The technical result to which the claimed invention is aimed is to increase the accuracy and stability of a micromechanical gyroscope with a reduced temperature effect, by adjusting the natural frequency of the primary oscillations of the SE and adjusting the frequency of the secondary oscillations to eliminate quadrature error, as well as the ease of implementation, configuration and calibration system and receiving a digital output signal by implementing a digital control circuit.

The specified technical result is achieved by the fact that the control system of the micromechanical gyroscope contains a signal conversion unit, consisting of analog-digital and digital-to-analog converters and interacting with the signal processing unit, according to the invention, the signal processing unit is made in the form of an excitation unit and a secondary oscillation processing unit, and the signal conversion unit is equipped with amplifiers of the output signals of digital-to-analog converters receiving signals from the excitation unit and the processing unit secondary oscillations, and adders receiving analog signals from amplifiers of output signals and excitation and processing units of secondary oscillations.

The presence in the claimed invention features that distinguish it from the prototype, allows us to consider it appropriate to the condition of "novelty."

New features that contain a distinctive part of the claims are not identified in technical solutions for a similar purpose, on this basis we can conclude that the claimed invention meets the condition of "inventive step".

The invention is illustrated by drawings.

In FIG. 1 is a structural diagram of a control system of a micromechanical gyroscope.

In FIG. 2 - excitation unit.

In FIG. 3 - processing unit of the secondary vibrations.

The control system of the micromechanical gyroscope contains a conversion unit and a signal processing unit interacting with a sensitive element of the micromechanical gyroscope (ChE MMG) 1.

ChE MMG 1 includes capacitive sensors of primary and secondary vibrations with outputs 4 and 6, respectively, electrostatic micro drives of primary and secondary vibrations with inputs 3 and 5, respectively, and a rotor with input 2, which is a common electrode for sensors and electric micro drives of primary and secondary vibrations and receiving a signal from a charge pump 7.

The signal conversion unit consists of capacitors of voltage to voltage 9 and 11, interacting with analog-to-digital converters (ADCs) 16 and 19, respectively, digital-to-analog converters (DACs) 14, 15, 17, 18, amplifiers 12, 13, amplifying output signals digital-to-analog converters 14 and 17, respectively, and adders 8 and 10. Adders 8 and 10 receive input signals from amplifiers 12, 13 and from digital-to-analog converters 15 and 18, respectively (Fig. 1).

The signal processing unit is made in the form of an excitation unit 26 and a secondary oscillation processing unit 27. The excitation unit 26 receives an input signal from the ADC 16 to input 22 and provides output signals to the DACs 14 and 15 from outputs 20 and 21, respectively. The processing unit of the secondary oscillations 27 receives the input signal from the ADC 19 to the input 25 and supplies the output signals to the DAC 17 and 18 from the outputs 23 and 24, respectively (Fig. 1).

A capacitive sensor of primary vibrations, a capacitance-to-voltage converter 9, ADC 16, an excitation block 26, a DAC 14 and 15, an amplifier 12, an adder 8 and an electrostatic micro-drive of primary vibrations form an MMG primary excitation excitation circuit.

A capacitive sensor of secondary oscillations, a capacitance to voltage converter 11, ADC 19, a secondary oscillation processing unit 27, a DAC 17 and 18, an amplifier 13, an adder 10 and an electrostatic secondary micromotor drive form a secondary oscillation processing circuit MMG.

The excitation block 26 (Fig. 2) contains a phase detector 33 receiving a signal from input 22 and transmitting a signal to an integrator 37 connected to a digital frequency synthesizer 32 and a subtraction unit 31, to the second input of which a signal from the output of the reference register 36 is received. The output signal the digital frequency synthesizer 32 is fed to the inputs of the phase detector 33 and the automatic gain control unit 30, which receives the second input signal from the input 22 of the excitation unit 26 and transmits the output signal to the output 21 of the excitation unit 26. The digital synthesizer Note 32 also generates the output signals of the detection 34 and 35, necessary for detecting the useful and quadrature components of the signal in the processing unit of the secondary oscillations 27. The output signal of the detection 34 corresponds to the signal with the phase 90 ° -ϕ90, and the output signal of the detection 35 to the signal with the zero phase - ϕ0. The output of the subtraction unit 31 is connected to the input of the controller 29, the output signal from which is transmitted to the output 20 of the excitation unit 26. The digital frequency synthesizer 32, the phase detector 33, and the integrator 37 form a phase-locked loop.

The secondary vibration processing unit 27 (Fig. 3) contains a controller 39 that receives an input signal from input 25 and provides an output signal to the inputs of phase detectors 41, 42 and to output 24 of the secondary vibration processing unit 27. The output signals of phase detectors 41 and 42 are fed to inputs of low pass filters 40 and 43, respectively. The output of the low-pass filter 40 interacts with the input of the controller 38, the output signal from which is output to the output 23 of the secondary oscillation processing unit 27. The output signal of the low-pass filter 43 is fed to the output 28 of the control system of the micromechanical gyroscope.

The device operates as follows.

The signal processing frequency F _s of the excitation units 26 and the secondary oscillation processing 27 is synchronous with the frequency of the ADCs 16, 19 and the DACs 14, 15, 17, 18, and also synchronously with the frequency of the charge pump generator 7. The signal processing frequency F _S is much higher than the frequency natural vibrations of the SE MMG 1.

To convert the capacitance of the sensors of the primary and secondary oscillations of the SE MMG 1, a rectangular signal of a given amplitude and frequency is supplied to the input 2 of the rotor of the SE MMG 1 from the “pump” generator of charge 7.

When primary oscillations occur, the EM MMG 1 capacitive sensor of the primary oscillations supplies a signal to output 4, which in the converter 9 is converted to a voltage supplied to the ADC 16. Then the signal from the output of the ADC 16 is fed to the input 22 of the excitation block 26.

From input 22, a digital signal enters the phase-locked loop formed by a phase detector 33, an integrator 37, and a digital frequency synthesizer 32, balance occurs at the resonance frequency of the primary vibrations of the EM MMG 1, which ensures resonant excitation of the primary vibrations of the EM MMG. The automatic gain control unit 30 changes the amplitude of the excitation signal so that the amplitude of the signal recorded at input 22 remains constant. In the mode of steady-state oscillations, the digital code at the output of the integrator 37 will be proportional to the frequency of the primary oscillations of the MMG in accordance with the formula:

where F _MMG1 - the frequency of primary oscillations of MMG,

F _S - signal processing frequency.

n is the capacity of the internal register of the frequency synthesizer.

The subtraction unit 31 provides a subtraction from the value of the oscillation frequency H the value stored in the memory of the master register 36. The output of the subtraction unit 31 is connected to the input of the controller 29. which generates a signal for adjusting the frequency of the primary oscillations. The signal for adjusting the frequency of the primary oscillations from the output 20 of the excitation block 26 through the DAC 14 and the amplifier 12 together with the signal from the output 21 of the excitation block 26 passing through the DAC 15, by the adder 8 are converted to the stand voltage at the input 3 of the primary electrostatic micro-drive of the primary oscillations. The voltage of the stand due to the effect of negative rigidity reduces the natural frequency of the primary oscillations of the MMG. The tuning process is established when the signal at the input of the controller 29 becomes equal to zero, i.e. the value specified in the register 36 becomes equal to the value at the output of the integrator 37, which in turn is proportional to the value of the frequency of the primary oscillations in accordance with the above formula. Thus, changing the value of the code in the master register 36, you can change the frequency of the primary oscillations of the SE MMG 1.

To synchronize the frequency of the primary oscillations of the MMG with the frequency of the processing of the signals F _S in order to accurately detect the signals, half the period of the primary oscillations of the MMG should fit an equal number of periods of the synchronization signal F _S , but not less than two. Then the values specified in register 36 must correspond to the formula:

where N _peg is the value in the master register 36 corresponding to the synchronization condition,

n is the capacity of the internal register of the frequency synthesizer,

N is the coefficient of multiplicity, showing how many periods of the clock frequency Fs fit on half the period of primary oscillations of MMG. (N = 2, 3, 4 ...)

The master register 36 can be implemented as a set of predefined values in accordance with the formula, and the selection of the value in the register 36 can be carried out automatically by the value at the output of the controller 38.

Thus, the device provides a synchronous adjustment of the frequency of the primary oscillations in multiples of the signal processing frequency. Due to this, high detection accuracy is achieved and, as a consequence, a decrease in the level of gyro drift. In addition, the use of stable sources of frequency F _S provides stability and low temperature dependence of the frequency of primary oscillations of MMG, which also increases the accuracy of measurements.

When secondary oscillations occur, the EM MMG 1 capacitive sensor of the secondary oscillations supplies a signal to output 6, which in the converter 11 is converted to a voltage supplied to the ADC 19. Then the signal from the output of the ADC 19 is fed to input 25 of the secondary oscillation processing unit 27.

From input 25, a digital signal is supplied to controller 39, which forms compensatory feedback in the secondary oscillation circuit. At the output of the controller 39, with the help of phase detectors 41, 42 and 32 auxiliary input signals ϕ90 (34) and ϕ0 (35) generated by the digital synthesizer, the quadrature and useful signal components are detected. The useful component through the low-pass filter 43 is supplied to the output 28 and is fixed in digital form. The quadrature component through the low-pass filter 40 is fed to the input of the controller 38, which generates a signal for adjusting the frequency of the secondary oscillations. The signal for adjusting the frequency of the secondary oscillations from the output 23 of the secondary oscillation processing unit 27 through the DAC 17 and the amplifier 13 together with the signal from the output 24 of the secondary oscillation processing unit 27 passing through the DAC 18, by the adder 10 are converted to the stand voltage at the input 5 of the secondary electrostatic microdrive. The voltage of the stand due to the effect of negative stiffness reduces the natural frequency of the secondary vibrations. The value of the quadrature component depends on the degree of mismatch of the frequencies of the primary and secondary oscillations. Thanks to the introduced control loop, the natural frequency of the secondary oscillations is precisely adjusted to the frequency of the primary oscillations, and the quadrature component becomes equal to zero.

Thus, in the control system of the micromechanical gyroscope, coordination of the eigenfrequencies of the primary and secondary oscillations with the clock frequency of the circuit is achieved. Due to this, the accuracy of signal detection increases, the quadrature component is compensated, and as a result, the drift of the output signal decreases and the accuracy of the transforms increases.

Thus, the above information indicates the fulfillment of the following set of conditions when using the claimed invention:

- a tool embodying the claimed invention in its implementation, is intended for control and processing of MMG signals;

- for the claimed device in the form as it is described in the independent claim, the possibility of its implementation is confirmed;

- the tool embodying the claimed invention in the implementation, is able to provide increased accuracy and stability of the micromechanical gyroscope, as well as low temperature effect.

Therefore, the claimed invention meets the condition of "industrial applicability".

Claims (1)

A micromechanical gyroscope control system comprising a signal conversion unit consisting of analog-to-digital and digital-to-analog converters and interacting with a signal processing unit, characterized in that the signal processing unit is designed as an excitation unit and a secondary oscillation processing unit, and the signal conversion unit is equipped amplifiers of the output signals of digital-to-analog converters receiving signals from the excitation unit and the processing unit of the secondary oscillations, and adders receiving analog signals from amplifiers of output signals and excitation and processing units of secondary oscillations.

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