JP2008070131A - Angular velocity sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an angular velocity sensor for surely removing noise components, no matter what kinds of noise components may be superimposed on the output signals from charge amplifiers. <P>SOLUTION: This angular velocity sensor has a structure with a noise signal removal means 35, provided in between the charge amplifiers 28a and 28b in a detection circuit 27 and a synchronous detector 31 for removing noise signals generated in the output signals of the charge amplifiers 28a and 28b. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention particularly relates to an angular velocity sensor that can be used for attitude control and navigation of a moving body such as an aircraft, an automobile, a robot, a ship, and a vehicle and that has a failure diagnosis function.

  This type of conventional angular velocity sensor has a configuration as shown in FIGS.

  FIG. 5 is a perspective view of a conventional angular velocity sensor, and FIG. 6 is a block diagram showing a signal detection circuit in the angular velocity sensor.

  5 and 6, reference numeral 1 denotes a rectangular parallelepiped-shaped vibrator, and the vibrator 1 is provided with a pair of driving piezoelectric elements 2 and a detecting piezoelectric element 3 on the outer surface. Reference numeral 4 denotes an amplifier. The amplifier 4 converts the electric charge generated from the detection piezoelectric element 3 in the vibrator 1 into a voltage and amplifies it.

  Next, the operation of the conventional angular velocity sensor configured as described above will be described.

  A driving AC voltage is applied to the driving piezoelectric element 2 to excite it at the natural frequency of the vibrator 1, and the vibrator 1 is vibrated in the arrangement direction X of the two driving piezoelectric elements 2. Is applied to the vibrator 1, a Coriolis force is generated in the direction Y perpendicular to the X direction and the Z direction, and this is detected as a charge by the detecting piezoelectric element 3. The output signal is converted by the amplifier 4.

  Here, considering the case where a noise signal is generated in the output signal from the amplifier 4, in the conventional angular velocity sensor, a pair of angular velocity sensors are prepared as shown in FIG. By providing the common component extraction unit 6 that extracts only the common component, the noise signal is removed by utilizing the fact that the common component has few noise components.

As prior art document information relating to the invention of this application, for example, Patent Document 1 is known.
JP-A-6-174475

  However, in the conventional configuration, when a common noise component is included in the output signal from the amplifier 4 in the pair of angular velocity sensors, the noise component is also included in the output signal from the common component extraction unit 6. Thus, there is a problem that an accurate angular velocity cannot be detected.

  The present invention solves the above-described conventional problems, and provides an angular velocity sensor that can reliably remove a noise component regardless of what noise component is included in an output signal from a charge amplifier. It is the purpose.

  In order to achieve the above object, the present invention has the following configuration.

  According to a first aspect of the present invention, a vibrator, a drive circuit for driving the vibrator with a predetermined amplitude and frequency, and a vibrator by a Coriolis force when an angular velocity is loaded on the vibrator. A charge amplifier that amplifies the generated charge and converts it into a voltage, a synchronous detector that synchronously detects an output signal from the charge amplifier with an output signal from the drive circuit, and a smoothing circuit that smoothes the output signal of the synchronous detector And a noise signal removal means for removing a noise signal generated in the output signal of the charge amplifier is provided between the charge amplifier and the synchronous detector in the detection circuit. Since the noise signal removing means for removing the noise signal generated in the output signal of the charge amplifier is provided between the charge amplifier and the synchronous detector in the detection circuit, the output signal from the amplifier is Whatever noise component is riding, and has a effect that can be removed reliably noise component.

  According to the second aspect of the present invention, in particular, the noise signal removing means divides the CR oscillator and the output signal of the CR oscillator to divide the frequency of the noise signal output from the charge amplifier. A phase divider for outputting the output signal, a phase shifter for converting the phase of the output signal from the frequency divider into a signal having a phase obtained by inverting the noise signal from the charge amplifier, and the frequency divider The variable attenuator for adjusting the amplitude of the output signal and the amplitude of the noise signal from the charge amplifier to be substantially the same. According to this configuration, the output signal is output from the charge amplifier by the frequency dividing circuit. While outputting an output signal of substantially the same frequency as the noise signal, the phase of the output signal from the frequency divider circuit is converted to a phase signal obtained by inverting the noise signal from the charge amplifier by the phase shifter, and output. Furthermore, since the variable attenuator adjusts the amplitude of the output signal from the frequency divider circuit and the amplitude of the noise signal from the charge amplifier to be substantially the same, the output signal from the noise signal removing means is By adding to the output signal of the charge amplifier, the noise signal from the output signal of the angular velocity sensor can be reliably removed.

  According to the third aspect of the present invention, in particular, a plurality of frequency dividing circuits, phase shifters and variable attenuators constituting the noise signal removing means are provided, and each frequency dividing circuit, phase shifter and variable attenuator A synthesis circuit for synthesizing the output signal is provided so as to remove all noise signals having a plurality of frequencies generated in the output signal from the charge amplifier. According to this configuration, the noise signal removing means is configured. A plurality of frequency circuits, phase shifters and variable attenuators are provided, and a synthesis circuit for synthesizing output signals from the frequency divider circuits, phase shifters and variable attenuators is provided, and a plurality of frequencies generated in the output signal from the charge amplifier are provided. Since all of the noise signal is removed, even if the output signal from the charge amplifier includes a noise signal having a plurality of frequencies, a plurality of frequency dividing circuits, By adding the output signals from the synthesis circuit that synthesizes the output signals from the phase shifter and variable attenuator, it is possible to reliably remove all noise signals having a plurality of frequencies generated in the output signal from the amplifier. It has a working effect.

  As described above, the angular velocity sensor according to the present invention is generated in the vibrator by the Coriolis force when the vibrator is driven at a predetermined amplitude and frequency, and when the angular velocity is loaded on the vibrator. A charge amplifier that amplifies and converts the charge to a voltage; a synchronous detector that synchronously detects an output signal from the charge amplifier with an output signal from the drive circuit; and a smoothing circuit that smoothes the output signal of the synchronous detector; And a noise signal removing means for removing a noise signal generated in the output signal of the charge amplifier is provided between the charge amplifier and the synchronous detector in the detection circuit. It is possible to provide an angular velocity sensor that can reliably remove a noise component regardless of what noise component is present. Is shall.

  Hereinafter, an angular velocity sensor according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view of an angular velocity sensor according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a drive circuit and a detection circuit of the angular velocity sensor.

  In FIGS. 1 and 2, reference numeral 11 denotes a vibrator. The vibrator 11 includes a quadrangular columnar crystal drive electrode vibrating body 12, a quadrangular columnar crystal detection electrode vibrator 13, and a crystal connection portion 14. It is comprised by. The drive electrode vibrating body 12 is provided with drive electrodes 15a and 15b made of gold on four side surfaces. The detection electrode vibrating body 13 is provided in parallel with the drive electrode vibrating body 12, and monitor electrodes 16 made of gold are provided on the front and back surfaces thereof. The detection electrode vibrating body 13 is provided with a GND electrode 17 made of gold on the inner side surface, and a pair of detection electrodes 18a and 18b made of gold on the outer side surface. Reference numeral 19 denotes a drive circuit. The drive circuit 19 includes an amplifier 20 for inputting the electric charge of the monitor electrode 16 of the vibrator 11, a bandpass filter 21 for inputting an output signal of the amplifier 20, and an output of the bandpass filter 21. A rectifier 22 for inputting a signal and a smoothing circuit 23 for inputting an output signal of the rectifier 22 are configured. An AGC circuit 24 receives the output signal of the smoothing circuit 23 in the drive circuit 19 and amplifies or attenuates the output signal of the band-pass filter 21. Reference numeral 25 denotes a drive control circuit. The drive control circuit 25 inputs an output signal of the AGC circuit 24 and inputs a drive signal to the drive electrode 15a of the vibrator 11. Reference numeral 26 denotes an inverting amplifier. The inverting amplifier 26 inputs an output signal of the drive control circuit 25 and inputs a drive signal obtained by inverting the output signal of the drive control circuit 25 to the drive electrode 15b of the vibrator 11. It is.

  Reference numeral 27 denotes a detection circuit. The detection circuit 27 includes a charge amplifier 28a that converts a charge generated by Coriolis force in one of the pair of detection electrodes 18a and 18b of the vibrator 11 into a voltage, and a pair of detection electrodes 18a and 18b. A charge amplifier 28b for converting the charge generated by the Coriolis force to the other detection electrode 18b of the detection electrodes 18a and 18b into a voltage, and a differential amplifier 29 for inputting output signals of these charge amplifiers 28a and 28b, A phase shifter 30 for inputting the output signal of the differential amplifier 29, a synchronous detector 31 for inputting the output signal of the phase shifter 30, a smoothing circuit 32 for inputting the output signal of the synchronous detector 31, and the smoothing circuit A DC amplifier 33 that receives the output signal of the circuit 32 and amplifies and outputs an angular velocity signal is formed. Reference numeral 34 denotes a monitor terminal. The monitor terminal 34 is provided so as to detect an output signal from the differential amplifier 29. Reference numeral 35 denotes a noise signal removing unit. The noise signal removing unit 35 divides an output signal output from the first CR oscillator 36 and the first CR oscillator 36 and outputs the divided signal. 37, a first phase shifter 38 that converts and outputs the phase of the output signal from the first frequency divider 37, and a first phase adjuster for the amplitude of the output signal from the first phase shifter 38. A variable attenuator 39; a second CR oscillator 40; a second frequency divider circuit 41 that divides and outputs an output signal output from the second CR oscillator 40; and A second phase shifter 42 that converts and outputs the phase of the output signal from the frequency divider circuit 41 and a second variable attenuator 43 that adjusts the amplitude of the output signal from the second phase shifter 42 are provided. Further, the output signal from the first variable attenuator 39 and the second variable reduction The output signal from the vessel 43 combined and and a combining circuit 44 to be output.

  Next, the operation of the angular velocity sensor according to one embodiment of the present invention configured as described above will be described.

  When an AC voltage is applied to the drive electrodes 15 a and 15 b of the vibrator 11, the vibrator 11 resonates and charges are generated at the monitor electrode 16 of the vibrator 11. The electric charges generated in the monitor electrode 16 are input to the amplifier 20 in the drive circuit 19 and output as a sinusoidal output voltage. Then, the output voltage of the monitor electrode 16 is input to the band-pass filter 21, only the resonance frequency of the vibrator 11 is extracted, noise components are removed, and a sine waveform as shown in FIG. . Further, the output signal of the bandpass filter 21 is input to the rectifier 22 to convert the negative voltage component into a positive voltage, and then input to the smoothing circuit 23 to be converted into a DC voltage signal. When the DC voltage signal of the smoothing circuit 23 is large, the AGC circuit 24 attenuates the output signal of the bandpass filter 21. On the other hand, when the DC voltage signal of the smoothing circuit 23 is small, Is for inputting a signal for amplifying the output signal of the band-pass filter 21 to the drive control circuit 25 and adjusting the vibration of the vibrator 11 to have a constant amplitude.

  Here, when the vibrator 11 rotates at an angular velocity ω around the central axis in the longitudinal direction of the vibrator 11 in a state in which the drive electrode vibrating body 12 of the vibrator 11 is bending-vibrated at a speed v in the vibration direction, A Coriolis force of F = 2 mV × ω is generated in the detection electrode vibrating body 13 of the vibrator 11. Due to this Coriolis force, a charge as shown in FIG. 3 (b) is generated in one detection electrode 18a of the pair of detection electrodes 18 of the detection electrode vibrating body 13, and the other detection electrode 18b is shown in FIG. 3 (c). A charge as shown is generated. Since the charges generated in the pair of detection electrodes 18 are generated by the Coriolis force, the phase of the charge generated in one detection electrode 18a advances by 90 degrees from the signal generated in the monitor electrode 16, and the other detection electrode 18b. The phase of the charge generated at 270 is advanced by 270 degrees. The differential amplifier 29 converts the charge generated from one detection electrode 18a into an output voltage as shown in FIG. The amplifier 28b amplifies the charge generated from the other detection electrode 18b and converts it into an output voltage as shown in FIG.

  Then, the output signals of the charge amplifier 28a and the charge amplifier 28b are input to the differential amplifier 29, and the differential amplifier 29 outputs a differential output signal by taking the differential. Further, the phase shifter 30 delays the output voltage of the differential amplifier 29 by 90 degrees and converts it into an output voltage as shown in FIG. Then, the output signal of the phase shifter 30 is input to the synchronous detector 31, and phase detection is performed at the period of vibration of the bandpass filter 21 in the drive circuit 19, and the negative voltage component of the output voltage of the phase shifter 30 is positive voltage. To obtain an output signal as shown in FIG. The output voltage of the synchronous detector 31 is smoothed and amplified by the smoothing circuit 32 and the DC amplifier 33 to obtain an output signal as shown in FIG. The output signal of the DC amplifier 33 is input as an angular velocity signal to a counterpart computer (not shown) or the like to detect the angular velocity.

  Here, considering the case where a noise signal having a frequency higher than the frequency of the angular velocity signal is on the output signal from the differential amplifier 29 as shown in FIG. If the detector 31 performs synchronous detection and inversion according to the drive frequency of the drive circuit 19 and then smoothes it by the smoothing circuit 32, an error component will appear in the output signal from the DC amplifier 33. Therefore, when an output signal from the differential amplifier 29 is taken out from the monitor terminal 34 and input to an FFT analyzer (not shown) and subjected to frequency analysis, it corresponds to the original angular velocity as shown in FIG. In addition to the frequency components, harmonic frequency components as shown in FIGS. 4C and 4D are output. Therefore, in the angular velocity sensor according to the embodiment of the present invention, the output signal from the first CR oscillator 36 is frequency-divided by the first frequency divider 37, and then the first phase shifter 38 is used to An output signal having the same amplitude as that shown in FIG. 4C is output by outputting a signal obtained by inverting the phase of the output signal shown in c) and adjusting the output signal by the first variable attenuator 39. The output signal as shown in FIG. 4E is output. Similarly, after the output signal from the second CR oscillator 40 is frequency-divided by the second frequency dividing circuit 41, the second signal is output. 4 is output by inverting the phase of the output signal shown in FIG. 4D, and the output signal is adjusted by the second variable attenuator 43, as shown in FIG. 4D. An output signal having the same amplitude as that shown in FIG. The output signal from the first differential attenuator 39 and the output signal from the second variable attenuator 43 are synthesized by the synthesis circuit 44, and the output signal from the differential amplifier 29 is output. 4 (c) and FIG. 4 (d) is removed, the component consisting of noise signals is removed, and with such a configuration, FIG. 4 (b) Therefore, an accurate output signal corresponding to the angular velocity can be obtained from the angular velocity sensor via the synchronous detector 31, the smoothing circuit 32, and the DC amplifier 33. Can be output.

  In the above-described embodiment of the present invention, the noise signal removing means 35 outputs the first CR oscillator 36 and the output signal from the differential amplifier 29 by dividing the output signal of the first CR oscillator 36. A first frequency dividing circuit 37 that outputs an output signal having substantially the same frequency as the noise signal to be generated, and the phase of the output signal from the first frequency dividing circuit 37 is inverted with respect to the noise signal from the differential amplifier 29. The first phase shifter 38 that converts and outputs the signal of the same phase, the amplitude of the output signal from the first frequency divider 37 and the amplitude of the noise signal from the differential amplifier 29 are made substantially the same. The first variable attenuator 39 that adjusts to the first frequency attenuator 39 outputs an output signal having substantially the same frequency as the noise signal output from the differential amplifier 29 by the first frequency divider 37, and The phase shifter 38 of the first The phase of the output signal from the frequency circuit 37 is converted into a signal having a phase obtained by inverting the noise signal from the differential amplifier 29, and the first frequency attenuator 39 is used to convert the output signal. Since the amplitude of the output signal from 37 and the amplitude of the noise signal from the differential amplifier 29 are adjusted to be substantially the same, the output signal from the noise signal removing means 35 is used as the output signal of the differential amplifier 29. By adding, the effect that the noise signal from the output signal of the angular velocity sensor can be surely removed is obtained.

  In the above-described embodiment of the present invention, the noise signal removing unit 35 includes a first frequency divider 37, a second frequency divider 41, a first phase shifter 38, a second phase shifter 42, The first variable attenuator 39 and the second variable attenuator 43, and the output signal via the first frequency divider 37, the first phase shifter 38 and the first variable attenuator 39, 2, a synthesis circuit 44 for synthesizing the output signal via the second frequency divider 41, the second phase shifter 42, and the second variable attenuator 43 is provided. Therefore, even when the output signal from the differential amplifier 29 includes a noise signal having two frequencies, the first frequency dividing circuit 37 and the first phase are eliminated. Output signal via the attenuator 38 and the first variable attenuator 39 By adding the output signals from the second frequency divider 41, the second phase shifter 42, and the second variable attenuator 43, two frequencies generated in the output signal from the differential amplifier 29 are formed. An effect is obtained that both noise signals can be reliably removed.

  The angular velocity sensor according to the present invention has an effect that the noise component can be surely removed regardless of what noise component is included in the output signal from the charge amplifier. It is useful as an angular velocity sensor used for attitude control and navigation of a moving body such as an automobile, a robot, a ship, and a vehicle.

The perspective view of the angular velocity sensor in one embodiment of this invention Block diagram showing drive circuit and detection circuit of same angular velocity sensor (A)-(h) Waveform diagram which shows the output signal in the operating state of the same angular velocity sensor (A)-(f) Waveform diagram which shows the state which the noise signal removal means in the same angular velocity sensor operated. A perspective view of a conventional angular velocity sensor Block diagram showing the operating state of the angular velocity sensor

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Oscillator 19 Drive circuit 27 Detection circuit 28a, 28b Charge amplifier 31 Synchronous detector 32 Smoothing circuit 35 Noise signal removal means 36, 40 CR oscillator 37, 41 Frequency dividing circuit 38, 42 Phase shifter 39, 43 Variable attenuator 44 Synthesis circuit

Claims (3)

A vibrator, a drive circuit that vibrates the vibrator with a predetermined amplitude and frequency, and a charge that amplifies the charge generated in the vibrator by Coriolis force when the vibrator is loaded with an angular velocity and converts it into a voltage. A detection circuit comprising: an amplifier; a synchronous detector for synchronously detecting an output signal from the charge amplifier with an output signal from the drive circuit; and a smoothing circuit for smoothing the output signal of the synchronous detector; An angular velocity sensor provided with a noise signal removing means for removing a noise signal generated in the output signal of the charge amplifier between the charge amplifier and the synchronous detector. The noise signal removing means includes a CR oscillator, a frequency dividing circuit that divides the output signal of the CR oscillator to output an output signal having substantially the same frequency as the noise signal output from the charge amplifier, and the frequency dividing circuit. A phase shifter that converts the phase of the output signal from the circuit into a signal having a phase obtained by inverting the noise signal from the charge amplifier, and the amplitude of the output signal from the frequency divider circuit and the amplitude of the noise signal from the charge amplifier The angular velocity sensor according to claim 1, comprising: a variable attenuator that adjusts so that they are substantially the same. A plurality of frequency dividers, phase shifters and variable attenuators constituting the noise signal removing means are provided, and a synthesis circuit for synthesizing output signals from the respective frequency dividers, phase shifters and variable attenuators is provided. 3. An angular velocity sensor according to claim 2, wherein all of the noise signal having a plurality of frequencies generated in the output signal is removed.

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