JP2008070132A - Angular velocity sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an angular velocity sensor that surely cancels error signals generated in output signal, when excessive impact is given to a vibrator. <P>SOLUTION: In this angular velocity sensor, a phase shifter 31 is provided with an amplitude attenuation means, comprising a changeover switch changing over between resistance values of first and second injection resistances in the phase shifter 31, to attenuate the amplitude of an output signal from a differential amplifier 29. As a result, the error signals from the output signals can be surely canceled. <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 FIG.

  FIG. 9 is a block diagram showing a detection circuit in a conventional angular velocity sensor.

  In FIG. 9, 1 is a vibrator. Reference numeral 2 denotes a drive circuit, which drives the vibrator 1 with a predetermined amplitude and frequency. Reference numeral 3 denotes a detection circuit. The detection circuit 3 amplifies a charge generated in the vibrator 1 by Coriolis force when an angular velocity is loaded on the vibrator 1, and an output signal of the charge amplifier 4 A phase shifter 5 composed of an operational amplifier for changing the phase, a synchronous detector 6 for synchronously detecting an output signal from the phase shifter 5 with an output signal from the drive circuit 2, and an output signal from the synchronous detector 6 being smoothed And a DC output circuit 7 that amplifies and amplifies the circuit.

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

  In a state where the conventional angular velocity sensor is excited at the natural frequency of the vibrator 1, when an angular velocity Ω centering on the axial direction Z of the vibrator 1 is applied to the vibrator 1, the Coriolis force is applied to the vibrator 1. This is detected as an electric charge, and converted into an output signal by the detection circuit 3, thereby detecting the angular velocity.

  Here, due to the imbalance of the shape of the vibrator 1, an error signal as shown in FIG. 10A is generated by the charge amplifier 4 and the conventional detection circuit 3 even though the angular velocity is not loaded on the vibrator 1. Considering the case where the signal is generated through the phase shifter 5, in the conventional angular velocity sensor, the output signal is synchronized with the output signal in the drive circuit 2 as shown in FIG. Is converted into the signal shown in FIG. Then, since it is smoothed by the DC output circuit 7, the error signal becomes a zero output value, whereby the error signal generated due to the imbalance of the shape of the vibrator 1 can be canceled.

As prior art document information relating to the invention of this application, for example, Patent Document 1 is known.
JP 2003-247828 A

  However, in the above-described conventional configuration, when an error signal generated by an excessive shock applied to the vibrator 1 exceeds the upper output saturation voltage of the phase shifter 5, as shown in FIG. Since a part of the output reaches a peak, generally, the difference between the upper output saturation voltage and the reference potential in the synchronous detector 6 is smaller than the difference between the lower output saturation voltage and the reference potential. As shown in FIG. 11B, the output below the reference potential increases, and as a result, an error signal is output from the DC output circuit 7 as shown in FIG. Was.

  The present invention solves the above-described conventional problems, and an object thereof is to provide an angular velocity sensor capable of reliably canceling an error signal generated when an excessive shock is applied to a vibrator from an output signal. It is.

  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 to a voltage, and changes the phase of the output signal from the charge amplifier, and the reference potential is shifted from the middle point of the upper output saturation voltage and the lower output saturation voltage. A phase shifter composed of an operational amplifier, a synchronous detector for synchronously detecting an output signal from the phase shifter with an output signal from the drive circuit, a smoothing circuit for smoothing the output signal of the synchronous detector, and the smoothing circuit An amplitude that attenuates the amplitude of the output signal from the charge amplifier by switching the resistance value of the injection resistor in the phase shifter. Attenuating means is provided in the phase shifter, and an amplitude amplifying means for amplifying an output signal from the smoothing circuit by switching a resistance value of the injection resistor in the DC amplifier is provided in the DC amplifier, and the attenuation rate of the amplification attenuating means and the amplitude amplification are provided. According to this configuration, the amplitude attenuating means for attenuating the amplitude of the output signal from the charge amplifier by switching the resistance value of the injection resistor in the phase shifter is phase-adjusted. Therefore, the error signal generated when an excessive shock is applied to the vibrator will not be higher than the upper output saturation voltage or lower than the lower output saturation voltage of the phaser. Therefore, after the signal conversion in the synchronous detector, the output below the reference potential does not increase and the result is , And has a effect that the error signal from the output signal can be reliably canceled.

  According to a second aspect of the present invention, a vibrator, a drive circuit that vibrates the vibrator with a predetermined amplitude and frequency, and the vibrator by Coriolis force when an angular velocity is applied to the vibrator. A charge amplifier that amplifies the generated charge and converts it into a voltage, a phase shifter that changes the phase of the output signal from the charge amplifier, and synchronously detects the output signal from the phase shifter with the output signal from the drive circuit And a synchronous detector having at least two operational amplifiers whose reference potentials are deviated from the midpoint of the upper output saturation voltage and the lower output saturation voltage, a smoothing circuit for smoothing the output signal of the synchronous detector, A DC amplifier that amplifies and outputs the output signal of the smoothing circuit, and switches the number of operational amplifiers in the synchronous detector to attenuate the amplitude of the output signal from the phase shifter. Means is provided in the synchronous detector, and an amplitude amplifying means for amplifying an output signal from the smoothing circuit by switching a resistance value of the injection resistor in the DC amplifier is provided in the DC amplifier, and the attenuation rate of the amplitude attenuating means and the amplitude amplification are provided. According to this configuration, the amplitude attenuating means for attenuating the amplitude of the output signal from the phase shifter by switching the number of operational amplifiers in the synchronous detector is detected synchronously. Therefore, the error signal generated when an excessive shock is applied to the vibrator will not be higher than the upper output saturation voltage or lower than the lower output saturation voltage of the operational amplifier in the synchronous detector. Because part of the output signal does not reach its peak, there are many outputs below the reference potential after signal conversion in the synchronous detector. Becomes also eliminated, as a result, those having effect that the error signal from the output signal can be reliably canceled.

  In the invention according to claim 3 of the present invention, in particular, a determination circuit is provided between the charge amplifier and the phase shifter, and an output signal from the charge amplifier is determined by the determination circuit to determine the amplitude attenuation means in the phase shifter. The resistance value is switched. According to this configuration, the output signal from the charge amplifier can be constantly monitored.

  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. Amplifier that amplifies and converts the generated charge into a voltage, and an operational amplifier that changes the phase of the output signal from the charge amplifier and shifts the reference potential from the midpoint of the upper and lower output saturation voltages A phase detector comprising: a synchronous detector for synchronously detecting an output signal from the phase shifter with an output signal from the drive circuit; a smoothing circuit for smoothing the output signal of the synchronous detector; and an output of the smoothing circuit And a DC amplifier composed of an operational amplifier for amplifying and outputting the signal, and switching the resistance value of the injection resistor in the phase shifter to attenuate the amplitude of the output signal from the charge amplifier A width attenuating means is provided in the phase shifter, and an amplitude amplifying means for amplifying an output signal from the smoothing circuit by switching a resistance value of the injection resistor in the DC amplifier is provided in the DC amplifier, and the attenuation rate and the amplitude of the amplification attenuating means are provided. According to this configuration, the amplitude attenuating means that attenuates the amplitude of the output signal from the charge amplifier by switching the resistance value of the injection resistor in the phase shifter. Since it is provided in the phase shifter, the error signal generated when an excessive shock is applied to the vibrator will not be higher than the upper output saturation voltage of the phase shifter or lower than the lower output saturation voltage. Since part of the signal never reaches a peak, the output below the reference potential does not increase after signal conversion in the synchronous detector. Results, in which an excellent effect that the error signal from the output signal can be reliably canceled.

  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 determination circuit 30 for determining an output signal of the differential amplifier 29, a phase shifter 31 composed of an operational amplifier for inputting the output signal of the differential amplifier 29, and a synchronous detector 32 for inputting the output signal of the phase shifter 31 The smoothing circuit 33 for inputting the output signal of the synchronous detector 32 and the output signal of the smoothing circuit 33 are inputted and amplified for angular velocity. It is constituted by a DC amplifier 34 consisting of an operational amplifier to output a signal.

  As shown in FIG. 3, the determination circuit 30 in the detection circuit 27 includes a first comparator 35 and a second comparator 36, and an output signal from the differential amplifier 29 is 3.8V. In the above case, a switching signal is sent from the first comparator 35 to the phase shifter 31. On the other hand, when the output signal from the differential amplifier 29 is 0.7 V or less, the second comparator 36 sends it to the phase shifter. A switching signal is sent to 31. The phase shifter 31 in the detection circuit 27 has a reference potential of 2.5 V, an upper output saturation voltage set to 4.0 V, and a lower output saturation voltage set to 0.5 V, and the reference potential 2.5 V is set to the upper side. It is shifted upward from 2.25V, which is the midpoint between the output saturation voltage 4.0V and the lower output saturation voltage 0.5V.

  In addition, the phase shifter 31 is provided with a changeover switch 37 as shown in FIG. 4, and the changeover switch 37 allows either the first injection resistor 38 or the second injection resistance 39 in the phase shifter 31 to be selected. One is selected. Then, when the changeover switch 37 selects the second injection resistor 39 by the combination of the first injection resistor 38, the second injection resistor 39, and the feedback resistor 40, the phase shifter 31 sets the first injection resistor 38. Compared with the case where the changeover switch 37 is selected, the amplification factor of the phase shifter 31 is set to be 50%. As shown in FIG. 5, the DC amplifier 34 in the detection circuit 27 is provided with a changeover switch 41, and the changeover switch 41 causes the first injection resistor 42 and the second injection resistor 43 in the DC amplifier 34 to be provided. Either one of them is selected. When the changeover switch 41 selects the second injection resistor 43 by the combination of the first injection resistor 42, the second injection resistor 43, and the feedback resistor 44, the DC amplifier 34 changes the first injection resistor 42. Compared to the case where the changeover switch 41 is selected, the amplification factor of the phase shifter 31 is set to be 200%.

  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, the noise component is removed, and a sine waveform as shown in FIG. 6A is output. . 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. 6B 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. 6C. 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 31 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 31 is input to the synchronous detector 32, 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 31 is positive voltage. To obtain an output signal as shown in FIG. The output voltage of the synchronous detector 32 is smoothed and amplified by the smoothing circuit 33 and the DC amplifier 34 to obtain an output signal as shown in FIG. The output signal of the DC amplifier 34 is input as an angular velocity signal to a counterpart computer (not shown) or the like to detect the angular velocity.

  Here, an excessive impact force acts on the vibrator 11 in the angular velocity sensor, and as shown in FIG. 7A, the maximum value of the output signal from the differential amplifier 29 is the upper output saturation voltage 4. In the angular velocity sensor according to the embodiment of the present invention, when the voltage becomes 4.1 V exceeding 0 V, the first comparator 35 in the determination circuit 30 is turned on, the changeover switch 37 of the phase shifter 31 is switched, and the second The injection resistor 39 is turned on. In this state, since the amplification factor of the phase shifter 31 is 50% as compared with the case where the changeover switch 37 is switched to the first injection resistor 38, as shown in FIG. The maximum value of the signal for phase conversion is 3.3V. Since the upper output saturation voltage of the phase shifter 31 is 4.0 V or less, the output signal from the phase shifter 31 does not reach a peak. Then, it is converted into the signal shown in FIG. 7C in synchronization with the output signal in the drive circuit 2. Since the error signal is canceled by the smoothing circuit 33 as shown in FIG. 7 (d), an accurate angular velocity can be detected.

  As described above, in one embodiment of the present invention, the amplitude of the output signal from the differential amplifier 29 is attenuated by switching the resistance values of the first injection resistor 38 and the second injection resistor 39 in the phase shifter 31. Since the phase shifter 31 is provided with an amplitude attenuating means including the changeover switch 37, an error signal generated when an excessive impact is applied to the vibrator 11 is equal to or higher than the upper output saturation voltage of the phase shifter 31 or lower output saturation. As a result, a part of the output signal does not reach a peak, so that the output below the reference potential does not increase after signal conversion in the synchronous detector 32. As a result, the effect that the error signal can be canceled reliably from the output signal can be obtained.

  Further, as shown in FIG. 5, the direct current amplifier 34 has a phase shifter when the changeover switch 41 selects the second injection resistor 43, compared with the case where the changeover switch 41 selects the first injection resistor 42. Since the amplification factor of 31 is set to be 200%, the output signal composed of the angular velocity is once attenuated to 50% by the phase shifter 31 as described above. Since these are 100% signals in total, the angular velocity signal itself does not change even if the changeover switch 37 in the phase shifter 31 and the changeover switch 41 in the DC amplifier 34 are operated. The same output signal can be output.

  In the angular velocity sensor according to the embodiment of the present invention, the case where the changeover switch 37 in the phase shifter 31 is switched to attenuate the output signal from the differential amplifier 29 has been described. As shown in FIG. Even when the changeover switch 46 is provided in the synchronous detector 32 in which a pair of operational amplifiers 45 are connected in series, and the number of the operational amplifiers 45 to be used is changed by the changeover switch 46, the amplification factor is changed. The same effects as those of the embodiment of the invention can be obtained.

  The angular velocity sensor according to the present invention has an effect that an error signal generated when an excessive impact is applied to the vibrator can be reliably canceled from the output signal, and in particular, an aircraft, an automobile, a robot, It is useful as an angular velocity sensor used for attitude control and navigation of a moving body such as a ship or 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 Circuit diagram showing determination circuit in detection circuit of same angular velocity sensor Circuit diagram showing phase shifter in detection circuit of same angular velocity sensor Circuit diagram showing DC amplifier in 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)-(d) Waveform diagram which shows the state which the amplitude attenuation | damping means in the same angular velocity sensor operated. The circuit diagram which shows the synchronous detector of the detection circuit of the angular velocity sensor in other embodiment of this invention The block diagram which shows the drive circuit and detection circuit of the conventional angular velocity sensor (A)-(c) Waveform diagram which shows the state which operate | moves in the state where excessive vibration was loaded to the same angular velocity sensor (A)-(c) Waveform diagram showing a state in which excessive vibration is loaded on the same angular velocity sensor and the error signal cannot be canceled

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Vibrator 19 Drive circuit 27 Detection circuit 28a, 28b Charge amplifier 30 Determination circuit 31 Phase shifter 32 Synchronous detector 33 Smoothing circuit 34 DC amplifier 38, 39, 45 Amplitude attenuation means 42, 43 Amplitude amplification means

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 phase shifter composed of an amplifier and an operational amplifier that changes the phase of the output signal from the charge amplifier and whose reference potential is shifted from the midpoint of the upper output saturation voltage and the lower output saturation voltage; DC detector comprising a synchronous detector for synchronously detecting an output signal with an output signal from the drive circuit, a smoothing circuit for smoothing the output signal of the synchronous detector, and an operational amplifier for amplifying and outputting the output signal of the smoothing circuit And an amplitude attenuating means for attenuating the amplitude of the output signal from the charge amplifier by switching the resistance value of the injection resistor in the phase shifter. An amplitude amplifying means for amplifying the output signal from the smoothing circuit by switching the resistance value of the injection resistor in the DC amplifier is provided in the DC amplifier, and the attenuation factor of the amplification attenuating means and the amplification factor of the amplitude amplifying means are opposite to each other. An angular velocity sensor configured as described above. 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. An amplifier, a phase shifter that changes the phase of the output signal from the charge amplifier, and the output signal from the phase shifter is synchronously detected with the output signal from the drive circuit, and the reference potential is set to the upper output saturation voltage and the lower output Synchronous detector having at least two operational amplifiers shifted from the midpoint of the saturation voltage, a smoothing circuit that smoothes the output signal of the synchronous detector, and a direct current that amplifies and outputs the output signal of the smoothing circuit An amplitude attenuating means for attenuating the amplitude of the output signal from the phase shifter by switching the number of operational amplifiers in the synchronous detector. And an amplitude amplifying means for amplifying an output signal from the smoothing circuit by switching a resistance value of the injection resistor in the DC amplifier, and the attenuation factor of the amplitude attenuating means and the amplification factor of the amplitude amplifying means are reciprocal to each other. An angular velocity sensor configured to be The determination circuit is provided between the charge amplifier and the phase shifter, and an output signal from the charge amplifier is determined by the determination circuit to switch the resistance value of the amplitude attenuating means in the phase shifter. Angular velocity sensor.

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