JP2008170294A - Angular velocity sensor - Google Patents

Abstract

The present invention relates to a compact angular velocity sensor that does not increase the capacity of a storage means and increase the angular velocity sensor and a vehicle control device to which an output signal thereof is input even if the resolution of correction data is increased. Is intended to provide.
An angular velocity sensor according to the present invention comprises correction data for correcting an output signal from a detection circuit 37 as a calibration curve of at least a quadratic curve and stores a coefficient of the calibration curve in a storage means. It is a thing.
[Selection] Figure 6

Description

  The present invention particularly relates to an angular velocity sensor used for attitude control of a moving body such as an aircraft, an automobile, a robot, a ship, and an automatic vehicle.

  A conventional angular velocity sensor of this type will be described with reference to the drawings.

  FIG. 8 is a block diagram showing a circuit configuration of a conventional angular velocity sensor.

  In FIG. 8, reference numeral 1 denotes a triangular prism-shaped vibrator, and two piezoelectric elements 2 are provided on two side surfaces of the vibrator 1 for driving and detection via a GND electrode 3. Further, electrodes 4 functioning for driving and detecting are provided on the surface of the piezoelectric element 2 in the vibrator 1. A monitor piezoelectric element 5 is provided on the remaining one side surface of the vibrator 1 via a GND electrode 3, and a monitor electrode 6 is provided on the surface of the monitor piezoelectric element 5. Reference numeral 7 denotes a drive control circuit. The drive control circuit 7 includes an oscillation circuit 8 and a phase circuit 9. The drive control circuit 7 inputs a signal from the monitor electrode 6 to the oscillation circuit 8 and outputs an output signal from the oscillation circuit 8 to the phase circuit. By inputting to the electrode 4 through 9, the vibrator 1 is vibrated stably. Reference numeral 10 denotes a detection circuit. The detection circuit 10 inputs a differential amplifier circuit 11 for inputting both output signals of the pair of electrodes 4, inputs an output signal of the differential amplifier circuit 11, and outputs a phase in the drive control circuit 7. A synchronous detection circuit 12 that performs synchronous detection according to the output signal of the circuit 9 and a rectification amplifier circuit 13 that inputs, rectifies, and amplifies the output signal of the synchronous detection circuit 12 are configured. Reference numeral 14 denotes a temperature detection means including a temperature sensor. The temperature detection means 14 is disposed in the vicinity of the vibrator 1 and detects the temperature around the vibrator 1. Reference numeral 15 denotes an A / D converter. The A / D converter 15 inputs an analog signal from the temperature detecting means 14 and converts it into a digital signal. Reference numeral 16 denotes a calculation means comprising a CPU, which outputs the output signal of the A / D converter 15 based on correction data stored in advance in the storage means 18 comprising EEPROM by an operation program pre-stored in the storage means 17 comprising EPROM. The result of the calculation is output as an output signal. Reference numeral 19 denotes an adder. The adder 19 converts the output signal of the arithmetic means 16 composed of the CPU into an output signal composed of an analog signal by the D / A converter 20, and converts it into an output signal of the rectifying amplifier circuit 13 in the detection circuit 10. It is to add.

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

  When an AC voltage is applied to the pair of electrodes 4 in the vibrator 1, the vibrator 1 is driven by self-excited vibration at a constant frequency by the oscillation circuit 8 and the phase circuit 9 based on the output signal output from the monitor electrode 6. When an angular velocity is applied to the vibrator 1 driven by self-excited vibration, electric charges are generated in the pair of piezoelectric elements 2 due to Coriolis force. After this electric charge is converted into a differential output voltage by the differential amplifier circuit 11 in the detection circuit 10, the synchronous detection circuit 12 performs synchronous detection in accordance with the phase of the phase circuit 9, and further amplifies it by the rectifying amplifier circuit 13. , And input to the adder 19 as an output signal.

  Here, considering the case where the ambient temperature of the angular velocity sensor changes from −20 ° C. to 60 ° C., in the conventional angular velocity sensor, as shown in Table 1, the temperature in the vicinity of the vibrator 1 is As detected by the temperature detecting means 14, the correction value for each temperature at that time is individually stored in the storage means 18 made of EEPROM and further stored in the storage means 17 made of EPROM as shown in Table 2. The correction amount is calculated by the corrected program. The correction amount is added to the output signal from the adder 19 to correct the output signal from the angular velocity sensor.

As prior art document information relating to the invention of this application, for example, Patent Document 1 is known.
Japanese Patent Application Laid-Open No. 5-296771

  However, in the above-described conventional configuration, the correction value based on the temperature is individually stored in the storage unit 18 composed of the EEPROM. Therefore, when the resolution of the correction data is increased, the amount of the correction data is increased. As a result, the angular velocity sensor and the vehicle control device to which the output signal is input are increased in size.

  The present invention solves the above-described conventional problem, and even if the resolution of the correction data is increased, the capacity of the storage means is increased, and the angular velocity sensor and the vehicle control device to which the output signal is input are increased. It is an object of the present invention to provide a small angular velocity sensor that does not have any.

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

  According to the first aspect of the present invention, a vibrator provided with a drive electrode, a detection electrode, and a monitor electrode, and a monitor signal from the monitor electrode in the vibrator are processed and input to the drive electrode, whereby vibration is generated. A driving circuit configured to oscillate a child with a constant amplitude, a detection circuit that processes an electric charge generated by Coriolis force acting when an angular velocity is applied to the vibrator, and generates an output signal; Storage means for storing correction data for correcting a fluctuation amount due to a temperature change of the output signal, and the correction data for correcting the output signal from the detection circuit is constituted by a calibration curve of at least a quadratic curve and this calibration. The coefficient of the curve is stored in the storage means. According to this configuration, the correction data for correcting the output signal from the detection circuit is at least a quadratic curve or more. Since it is configured with a calibration curve and the coefficient of the calibration curve is stored in the storage means, even if the resolution of the correction data is increased, the amount of correction data does not increase. This has the effect of reducing the capacity of the storage means.

  As described above, the angular velocity sensor according to the present invention includes a vibrator provided with a drive electrode, a detection electrode, and a monitor electrode, and processes the monitor signal from the monitor electrode in the vibrator and inputs the processed signal to the drive electrode. A drive circuit that oscillates at a constant amplitude, a detection circuit that generates an output signal by processing charges generated by Coriolis force acting when an angular velocity is applied to the vibrator, and an output from the detection circuit Storage means for storing correction data for correcting a fluctuation amount due to a temperature change of the signal, and the correction data for correcting the output signal from the detection circuit is constituted by a calibration curve of at least a quadratic curve, and the calibration curve. Since the coefficient is stored in the storage means, even if the resolution of the correction data is increased, the amount of correction data does not increase. The Le, it is possible to reduce the capacity of the storage unit, in which an excellent effect that the vehicle controller the angular velocity sensor and its output signal is input can be made compact.

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

  1 and 2, reference numeral 21 denotes a tuning-fork-shaped quartz crystal vibrator. The vibrator 21 has a square columnar detection electrode vibrating body 22 and a square columnar drive provided in parallel with the detection electrode vibrating body 22. The electrode vibrating body 23 includes a crystal connection portion 24 that connects one end of the detection electrode vibrating body 22 and one end of the drive electrode vibrating body 23. The drive electrode vibrating body 23 in the vibrator 21 is provided with drive electrodes 25 made of gold on four side surfaces. The monitor electrode 26 made of gold is provided on the front and back surfaces of the detection electrode vibrating body 22 in the vibrator 21, and the GND electrode 27 made of gold is provided on the inner side surface of the detection electrode vibrating body 22. On the outer side surface, a first detection electrode 28a and a second detection electrode 28b made of gold are provided. Reference numeral 29 denotes a drive circuit. The drive circuit 29 includes an amplifier 30 for inputting a charge of one monitor electrode 26 of the vibrator 21, a band pass filter (BPF) 31 for inputting an output signal of the amplifier 30, and the band. A rectifier 32 that inputs an output signal of a pass filter (BPF) 31 and a smoothing circuit 33 that inputs an output signal of the rectifier 32 are configured. Reference numeral 34 denotes an AGC circuit. The AGC circuit 34 inputs an output signal of the smoothing circuit 33 in the drive circuit 29 and amplifies or attenuates an output signal of the band pass filter (BPF) 31. Reference numeral 35 denotes a drive control circuit. The drive control circuit 35 inputs an output signal of the AGC circuit 34 and inputs a drive signal to the drive electrode 25 of the vibrator 21. Reference numeral 36 denotes an inverting amplifier. The inverting amplifier 36 inputs an output signal of the drive control circuit 35 and inputs a drive signal obtained by inverting the output signal of the drive control circuit 35 to the drive electrode 25 of the vibrator 21. .

  Reference numeral 37 denotes a detection circuit. The detection circuit 37 includes a first amplifier 39 that converts electric charges generated by the Coriolis force on the first detection electrode 28a of the vibrator 21 into a voltage, and a Coriolis force applied to the second detection electrode 28b. A second amplifier 41 that converts the generated charge into a voltage, a differential amplifier 42 that receives the output signals of the first amplifier 39 and the second amplifier 41, and a phase that inputs the output signal of the differential amplifier 42 43, a synchronous detector 44 for inputting the output signal of the phase shifter 43, a smoothing circuit 45 for inputting the output signal of the synchronous detector 44, and an input signal of the smoothing circuit 45 for amplification. And a DC amplifier 46 for outputting an angular velocity signal. Further, an adder 47 for adding correction data to the angular velocity signal from the DC amplifier 46 in the detection circuit 37 is provided, a temperature sensor 48 is provided in the vicinity of the vibrator 21, and an analog output signal of the temperature sensor 48 is provided. Is converted to a digital output signal. Further, a storage means 50 composed of an EEPROM is provided. The storage means 50 is not electrically connected to the detection circuit 37, and data for correcting an error in the output signal output from the DC amplifier 46 in the detection circuit 37. Is stored.

  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 electrode 25 of the vibrator 21, the vibrator 21 resonates and charges are generated at the monitor electrode 26 of the vibrator 21. The electric charges generated on the monitor electrode 26 are input to the amplifier 30 in the drive control circuit 35 and output as a sine waveform output voltage. Then, the output voltage of the amplifier 30 is input to a band pass filter (BPF) 31 to extract only the resonance frequency of the vibrator 21 and to remove a noise component to output a sine waveform as shown in FIG. To do. Further, by inputting the output signal of the band pass filter (BPF) 31 to the rectifier 32, the negative voltage component is converted to a positive voltage, and then input to the smoothing circuit 33 to be converted to a DC voltage signal. When the DC voltage signal of the smoothing circuit 33 is large, the AGC circuit 34 attenuates a signal that attenuates the output signal of the bandpass filter (BPF) 31, and when the DC voltage signal of the smoothing circuit 33 is small. Is for inputting a signal for amplifying the output signal of the bandpass filter (BPF) 31 to the drive control circuit 35 and adjusting the vibration of the vibrator 21 to have a constant amplitude. Here, when the vibrator 21 rotates at an angular velocity ω around the central axis in the longitudinal direction of the vibrator 21 in a state in which the drive electrode vibrating body 23 of the vibrator 21 is flexibly vibrated at a speed v in the vibration direction, this vibration occurs. A Coriolis force of F = 2 mV × ω is generated in the detection electrode vibrating body 22 of the child 21. Due to this Coriolis force, charges as shown in FIG. 3B are generated in the first detection electrode 28a provided on the detection electrode vibrating body 22, and the second detection electrode 28b as shown in FIG. 3C. Charge is generated. Then, the first amplifier 39 converts the electric charge generated from the first detection electrode 28a into an output voltage as shown in FIG. The second amplifier 41 inverts and amplifies the charge generated from the second detection electrode 28b and converts it into an output voltage as shown in FIG. Further, the differential amplifier 42 takes the differential of the output signals of the first amplifier 39 and the second amplifier 41, and further delays the phase of the output signal of the differential amplifier 42 by 90 degrees by the phase shifter 43. It converts into an output voltage as shown in 3 (f). Then, the output signal of the phase shifter 43 is input to the synchronous detector 44 and phase detection is performed at the period of vibration of the bandpass filter (BPF) 31 in the drive control circuit 35, and the negative voltage component of the output voltage of the phase shifter 43 is detected. Is converted to a positive voltage to obtain an output signal as shown in FIG. Then, the output voltage of the synchronous detector 44 is smoothed and amplified by the smoothing circuit 45 and the DC amplifier 46 to obtain an output signal as shown in FIG. Then, the output signal of the DC amplifier 46 of the detection circuit 37 is output to the outside as an angular velocity signal.

  Here, consider a case where an angular velocity sensor is installed in an engine room of an automobile and the temperature in the vicinity of the angular velocity sensor changes from −40 ° C. to 100 ° C.

First, as shown in FIG. 4, the angular velocity sensor is assembled to the inspection device 53 provided in the temperature chamber 52, and the temperature in the vicinity of the angular velocity sensor is set to −40 so that the conditions are the same as those in the engine room of the automobile. Change from 0 ° C to 100 ° C. Then, an output signal from the temperature sensor 48 at each temperature is input to the CPU 54 in the inspection device 53 via the A / D converter 49, and at the same time, an output signal from the angular velocity sensor when no angular velocity is applied is input to the CPU 54. Then, as shown in FIG. 5, the CPU 54 in the inspector 53 calculates correction data for each temperature such that the output signal of the angular velocity sensor for each temperature is always zero output of 2.5V. Next, this correction data is approximated by a quadratic equation as shown in FIG. 5, and the correction coefficients a = 7 × 10 ⁻⁶ , b = 9 × 10 ⁻⁴ , and c = 2.5 in Table 3 are set to EEPROM. Is stored in the storage means 50.

  When an angular velocity is applied to the automobile (not shown), an angular velocity signal is output from the detection circuit 37 in the angular velocity sensor. In this case, as shown in FIG. 6, the correction signal calculated by the CPU 56 in the vehicle control device 55 of the automobile (not shown) based on the correction data stored in the storage means 50 is output by the D / A converter 57. Convert to analog signal. The analog signal is added to the angular velocity signal output from the detection circuit 37 by the adder 47 to correct the output signal from the detection circuit 37, that is, the angular velocity signal.

  At this time, in the conventional angular velocity sensor, as shown in FIG. 7, the output signal of the angular velocity sensor in a state where the angular velocity is not applied every 1 ° C. from −40 ° C. to 100 ° C. is plotted, and shown in (Table 4). Since the correction data for each temperature is stored in the storage means 50 made of EEPROM, the angular velocity sensor and the vehicle control device 55 to which the output signal is input are large.

However, in the angular velocity sensor according to the embodiment of the present invention, the correction data for each temperature is approximated by a quadratic curve as shown in FIG. 5, and a calibration curve comprising a quadratic curve is stored in the storage means 50 comprising an EEPROM. The coefficients of a = 7 × 10 ⁻⁶ , b = 9 × 10 ⁻⁴ , and c = 2.5 are stored as shown in (Table 3). That is, the correction data for correcting the output signal from the detection circuit 37 is composed of a calibration curve of a quadratic curve, and the coefficient of this calibration curve is stored in the storage means 50. Therefore, the resolution of the correction data is reduced. Even if the value is increased, the amount of correction data does not increase, and the capacity of the storage means 50 can be reduced.

  Further, in the angular velocity sensor according to the embodiment of the present invention, the storage means 50 is constituted by an EEPROM. However, other than this, for example, it may be constituted by a flash memory or an EPROM. Even when the storage means 50 is configured by using it, it has the same effect as that of the embodiment of the present invention.

  In the angular velocity sensor according to the embodiment of the present invention, the correction data is composed of a calibration curve composed of a quadratic curve, but a polynomial higher than a cubic curve, a Lagrange interpolation curve, a Fargson curve, a spline Even when a calibration curve for interpolation is set using an interpolation curve, a Bezier polynomial curve, a Bezier spline curve, or the like, and the coefficients are stored in the storage means 50 made of EEPROM, the same as in the above-described embodiment of the present invention. It has the effect of.

  The angular velocity sensor according to the present invention is a small angular velocity that does not increase the capacity of the storage means and increase the angular velocity sensor and the vehicle control device to which the output signal is input even if the resolution of the correction data is increased. The present invention has an effect that a sensor can be provided, and is particularly useful as an angular velocity sensor used for posture control of a moving body such as an aircraft, an automobile, a robot, a ship, and an automatic vehicle.

The block diagram which shows the circuit structure of the angular velocity sensor in one embodiment of this invention Perspective view of transducer in same angular velocity sensor (A)-(h) The figure which shows the output signal in the same angular velocity sensor Block diagram showing a state of inspecting output characteristics in the same angular velocity sensor The figure which shows the state which approximates the correction data of the output signal in the same angular velocity sensor with a quadratic curve The block diagram which shows the state which adds the correction data of the memory | storage means in the same angular velocity sensor to an output signal via a vehicle control apparatus. The figure which shows the state which corrects the correction data of the output signal in the same angular velocity sensor with individual data Block diagram showing the circuit configuration of a conventional angular velocity sensor

Explanation of symbols

21 vibrator 25 drive electrode 26 monitor electrode 28a, 28b detection electrode 29 drive circuit 37 detection circuit 50 storage means

Claims (1)

A vibrator provided with a drive electrode, a detection electrode, and a monitor electrode, and a drive that vibrates the vibrator with a constant amplitude by processing a monitor signal from the monitor electrode in this vibrator and inputting it to the drive electrode A circuit, a detection circuit for processing an electric charge generated by Coriolis force applied when an angular velocity is applied to the vibrator, and generating an output signal, and a correction for correcting a fluctuation amount due to a temperature change of the output signal from the detection circuit Storage means for storing data, and the correction data for correcting the output signal from the detection circuit is constituted by a calibration curve of at least a quadratic curve and the coefficient of the calibration curve is stored in the storage means. Angular velocity sensor.

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