JP2011002295A - Angular velocity detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an angular velocity detection device capable of removing sufficiently an influence of a high-order resonance frequency of a vibrator.SOLUTION: This angular velocity detection device includes an excited and vibrated vibrator, a driving means for outputting a driving signal for exciting and vibrating the vibrator, a detection means for detecting displacement in a direction which is different from excitation vibration of the vibrator, and an angular velocity detection means for detecting an angular velocity around a direction orthogonal to both a direction of the excitation vibration and a direction of the displacement detected by the detection means on the basis of the displacement detected by the detection means. The angular velocity detection device also includes a temperature detection means for detecting a temperature. The driving means changes a mode of the driving signal corresponding to a temperature change detected by the temperature detection means.

Description

  The present invention relates to an angular velocity detection device that detects an angular velocity generated in a vibrator by exciting the vibrator.

  Conventionally, a vibrator is excited and oscillated along a first axis in a three-dimensional orthogonal coordinate system, and a vibration along a third axis caused by an angular velocity around the second axis is detected. There is known an angular velocity detection device for calculating the angular velocity. Such an angular velocity detection device is used as a yaw rate sensor by being mounted on a vehicle with the second axis as a vertical axis.

  One of the problems that occur in such an angular velocity detection device is that the vibrator performs higher-order vibration (vibration whose frequency is n times that of the excitation vibration) in response to the higher-order resonance frequency. It is done. When the vibrator performs high-order vibration, the vibration along the third axis includes a high-order component due to the relationship between the angular velocity and the high-order vibration. As a result, higher-order components are superimposed on the angular velocity signal to be output, resulting in an error.

  An invention of an angular velocity sensor whose main purpose is to eliminate this is disclosed (for example, see Patent Document 1). In addition to the main synchronous detection circuit that detects the fundamental wave synchronously, this sensor is equipped with a harmonic synchronous detection circuit that selectively extracts odd harmonics superimposed on the fundamental wave that cannot be removed by the main synchronous detection circuit. The signal processing for reducing the residual odd harmonic components is performed using the odd harmonic detection waveform extracted by the harmonic synchronous detection circuit from the main detection waveform from the main synchronous detection circuit.

  On the other hand, in view of the fact that the characteristics of the vibrator vary depending on the temperature environment of the apparatus, an invention has been disclosed regarding a vibrating gyroscope that performs bias compensation according to temperature data (see, for example, Patent Document 2).

JP 2006-47144 A JP 2006-194701 A

  However, in the conventional sensor described above, there is always a time for the excitation frequency and the higher-order resonance frequency of the vibrator to be synchronized. To do. For this reason, an error may be superimposed on the signal detected as the angular velocity, and the detection accuracy may decrease.

  Such inconvenience arises according to the temperature change of the apparatus. In this regard, the vibration gyro described in Patent Document 2 performs bias compensation according to temperature data.

  Here, the bias compensation data is measured in advance by a test, but there is no guarantee that an appropriate value is obtained when the environment such as the magnitude or amplitude of the angular velocity given to the apparatus changes. Therefore, there may be a case where measurement errors due to vibration displacement due to higher-order resonance of the vibrator cannot be sufficiently removed.

  The present invention has been made to solve such problems, and a main object thereof is to provide an angular velocity detection device capable of sufficiently eliminating the influence of the higher-order resonance frequency of the vibrator.

In order to achieve the above object, one embodiment of the present invention provides:
A vibrator to be vibrated,
Drive means for outputting a drive signal for exciting and vibrating the vibrator;
Detecting means for detecting displacement in a direction different from the excitation vibration in the vibrator;
An angular velocity detection device comprising: angular velocity detection means for detecting an angular velocity around a direction orthogonal to both the direction of the excitation vibration and the direction of displacement detected by the detection means based on the displacement detected by the detection means. Because
Temperature detecting means for detecting temperature,
The drive means changes the mode of the drive signal according to a change in temperature detected by the temperature detection means,
It is an angular velocity detection device.

  According to this aspect of the present invention, the influence of the higher-order resonance frequency of the vibrator can be sufficiently eliminated.

In one embodiment of the present invention,
For example, the driving unit is a unit that changes at least one of an amplitude, a limit of amplitude, and a bias of the driving signal in accordance with a change in temperature detected by the temperature detecting unit.

  ADVANTAGE OF THE INVENTION According to this invention, the angular velocity detection apparatus which can fully eliminate the influence of the high order resonant frequency of a vibrator | oscillator can be provided.

1 is a system configuration example of an angular velocity detection device 1 according to an embodiment of the present invention. It is a figure which shows a mode that the problem that the frequency component of the higher order vibration superimposed on the angular velocity detection signal will be contained in an angular velocity signal when the vibrator | oscillator 10 carries out the higher order vibration with respect to excitation vibration. It is a figure which shows the mode change of a drive signal according to the change of the temperature detected by the temperature sensor. It is an example of a configuration that the gain control circuit has. This is an example of the configuration of the booster circuit 44. This is an example of the configuration of the booster circuit 44. 2 is a system configuration example of the angular velocity detection device 1 when data of an input voltage of a VCO included in the PLL circuit 26 is supplied to a drive waveform adjustment circuit 42.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings.

[Basic configuration]
FIG. 1 is a system configuration example of an angular velocity detection device 1 according to an embodiment of the present invention. As shown in the drawing, the angular velocity detection device 1 includes a vibrator 10, a drive circuit 20, an excitation displacement detection circuit 22, a gain control circuit 24, a PLL (Phase-Locked Loop) circuit 26 as a basic configuration. , A frequency divider 28, a sensor displacement detection circuit 30, a synchronous detection circuit 32, and an integrator 34.

  The angular velocity detection device 1 is configured as, for example, a MEMS (Micro Electro Mechanical Systems) sensor. In this case, the vibrator 10 is formed so as to float on a support substrate (not shown), and is connected to a fixed portion protruding from the support substrate via a beam structure. This beam structure is a flat plate structure having a certain width in the direction toward the support substrate.

  With such a structure, the vibrator 10 can be displaced with a certain degree of freedom on a plane whose normal is the direction toward the pointing substrate.

  A plurality of electrodes for excitation and vibration detection (for detecting vibration in a certain X direction and for detecting vibration in the Y direction orthogonal to the X direction) are disposed around the vibrator 10. Here, the X direction and the Y direction are included in a plane whose normal is the direction toward the support substrate.

  The excitation electrode vibrates the vibrator in a certain X direction by electrostatic driving. The displacement in the X direction is detected by the vibration detection electrode in the X direction and output to the excitation displacement detection circuit 22. On the other hand, the displacement in the Y direction caused by the Coriolis force due to the angular velocity around the Z direction orthogonal to both the X direction and the Y direction is detected by the vibration detection electrode in the Y direction and output to the sensor displacement detection circuit 30. Is done.

  There are no particular restrictions on the shape of the vibrator 10 and the position where the electrodes are disposed, and any one may be used.

  Based on the amplitude value signal input from the gain control circuit 24, the drive timing signal input from the frequency divider 28, and the signal input from the booster circuit 44, which will be described later, the drive circuit 20 supplies an AC component to the excitation electrode. Is applied to the vibrator 10 to vibrate.

  The excitation displacement detection circuit 22 converts the electrostatic capacitance of the vibration detection electrode in the X direction into a voltage (Q / V conversion), and outputs an excitation detection signal demodulated to the gain control circuit 24 and the PLL circuit 26. .

  The gain control circuit 24 generates an instruction signal to the drive circuit 20 by comparing the target displacement (amplitude) of the vibrator 10 with the actual displacement indicated by the excitation detection signal. More specifically, the gain and the like of the difference element and the integral element in the feedback control for making the target displacement of the vibrator 10 coincide with the actual displacement are determined and output to the drive circuit 20.

  The PLL circuit 26 includes a phase comparator, a low-pass filter, a VCO, and the like. An excitation detection signal output from the excitation displacement detection circuit 22 and a drive timing signal output from the frequency divider 28 are input to the phase comparator. The phase comparator outputs a signal indicating these phase differences to the VCO via a low-pass filter.

  The frequency divider 28 shifts the phase of the signal input from the VCO, for example, by 90 degrees, and generates a drive timing signal and a detection timing signal having the same period as this. The drive timing signal is output to the drive circuit 20, and the detection timing signal is output to the synchronous detection circuit 32, respectively.

  With this configuration, the drive frequency of the drive circuit 20 can be locked at the resonance point of the vibrator 10.

  The sensor displacement detection circuit 30 converts the capacitance detected by the vibration detection electrode in the Y direction into a voltage (Q / V conversion), and outputs an angular velocity detection signal obtained by demodulating it to the synchronous detection circuit 32.

  The synchronous detection circuit 32 uses the detection timing signal generated by the frequency divider 28 as a reference, and generates a detection signal obtained by inverting the sign of a signal having a phase in a predetermined range among the angular velocity detection signals. As for the angular velocity detection signal and the detection signal, FIG. 2 described later can be referred to.

  The integrator 34 smoothes the detection signal generated by the synchronous detection circuit 32 and outputs an angular velocity signal to the outside.

  With such a configuration, an angular velocity signal corresponding to the amplitude of vibration around the Y direction generated by the angular velocity around the Z direction is generated and output to the outside. When the angular velocity detection device 1 is mounted on a vehicle, for example, it is installed so that the Z direction is a vertical direction, and is used as a yaw rate sensor that detects an angular velocity in the yaw direction of the vehicle.

[problem]
By the way, in such a configuration, the vibrator 10 may perform higher-order vibration with respect to the excitation vibration (vibration whose frequency is n times that of the excitation vibration) according to the resonance frequency. That is, when the frequency of excitation vibration or higher-order resonance gradually changes due to temperature changes, etc., and the odd-number multiple of the excitation vibration frequency matches the higher-order resonance frequency, the higher-order vibration superimposed on the angular velocity detection signal Are included in the angular velocity signal. In principle, there is no problem because even-order higher-order components cancel each other and become zero.

  FIG. 2 is a diagram showing how such inconvenience occurs. As shown in the figure, for example, when a third-order harmonic signal is superimposed on the angular velocity detection signal, the finally outputted angular velocity signal includes an error component.

[Characteristic configuration and processing]
Therefore, the angular velocity detection device 1 of the present embodiment has components such as the temperature sensor 40, the drive waveform adjustment circuit 42, and the booster circuit 44, and the excitation vibration of the vibrator 10 by the drive circuit 20 according to the temperature in the device. It was decided to change the mode. This is because the higher-order resonance frequency changes due to the temperature of the vibrator 10.

  FIG. 3 is a diagram illustrating a change in the driving signal according to a change in temperature detected by the temperature sensor 40. As shown in the figure, it is assumed that the upper limit and the lower limit of the amplitude of the drive signal output to the excitation electrode are set by the clamp voltage at room temperature. Next, when the temperature rises ((A) in the figure), the amplitude of the drive signal is reduced. When the temperature further rises ((B) in the figure), the DC bias voltage (DC component in the drive signal) is changed larger or smaller. When the temperature further rises and becomes high ((C) in the figure), the clamp voltage is greatly changed.

  By such control, it is possible to suppress the generation of vibration due to synchronization between the excitation vibration and the higher-order resonance vibration of the vibrator 10, and to maintain high detection accuracy of the angular velocity signal.

  That is, when the bias voltage is changed, the mechanical spring constant of the structure including the vibrator 10 can be changed. When the mechanical spring constant is changed, the frequency of the higher-order resonance of the vibrator 10 is changed. Therefore, the vibration displacement due to the higher-order resonance can be suppressed by changing the DC bias voltage of the drive signal.

  Further, when the waveform of the drive signal has a trapezoidal shape, it has a property as a rectangular wave and includes a frequency component different from its own frequency. Therefore, by adjusting the drive waveform, it is possible to prevent synchronization between another generated frequency component and a higher-order resonance frequency.

  The drive waveform adjustment circuit 42 outputs a signal (excitation amplitude adjustment signal) for changing the amplitude of the drive signal to the gain control circuit 24 based on the information input from the temperature sensor 40, and the amplitude limit value, and Signals for changing the bias (clamp voltage adjustment signal and DC bias adjustment signal) are output to the booster circuit 44. Note that it is not always necessary to change the amplitude of the drive signal, the limit value of the amplitude, and the bias, and some of them may be changed.

  As a configuration for realizing such control, the gain control circuit 24 has an integration circuit as shown in FIG. The gain control circuit 24 changes the capacitance of the capacitor based on the drive amplitude adjustment signal input from the drive waveform adjustment circuit 42, and adjusts the gain when generating the drive amplitude information from the excitation displacement information (excitation detection signal). .

  The booster circuit 44 has a plurality of configurations as shown in FIG. The booster circuit 44 changes the resistance value of the power line connecting the external power supply 44A (which may be generated inside the apparatus) and the operational amplifier 44B based on the clamp voltage adjustment signal, and changes the internal power supply voltage for boosting. The switch 44C is ON / OFF controlled based on the clamp voltage adjustment signal.

  The booster circuit 44 further has a configuration as shown in FIG. The booster circuit 44 has a Zener portion that is controlled to be switched based on the DC bias adjustment signal, and adjusts the DC bias voltage by changing the number of stages of the Zener and the potential at the terminal X.

  According to the angular velocity detection device 1 of the present embodiment described above, the excitation vibration and the higher-order resonance of the vibrator 10 are changed in order to change the mode of the excitation vibration of the vibrator 10 by the drive circuit 20 according to the temperature in the device. Generation of vibration due to synchronization with vibration can be suppressed, and the detection accuracy of the angular velocity signal can be maintained high. Therefore, the influence of the higher-order resonance frequency of the vibrator can be sufficiently eliminated.

  The best mode for carrying out the present invention has been described above by using the embodiments. However, the present invention is not limited to these embodiments, and various modifications can be made without departing from the gist of the present invention. And substitutions can be added.

  For example, the vibration-type angular velocity detection device as shown in the embodiment has variations in the drive resonance frequency in manufacturing, and individual variations occur in resonance modes that have a large influence on the angular velocity detection due to this variation. Data of the VCO input voltage (corresponding to the drive resonance frequency) of the VCO 26 may be supplied to the drive waveform adjustment circuit 42.

  FIG. 7 shows a system configuration example of the angular velocity detection device 1 when data of the input voltage of the VCO included in the PLL circuit 26 is supplied to the drive waveform adjustment circuit 42.

  The drive waveform adjustment circuit 42 adjusts the change of the drive signal as shown in FIG. 3 based on the supplied input voltage data of the VCO. Specifically, the temperature threshold value for changing to a different mode ((A) → (B), etc. in FIG. 3) is changed, or both the temperature information from the temperature sensor 40 and the frequency of the input voltage of the VCO are considered. Thus, the change of the driving signal mode is adjusted. Note that the temperature of the vibrator 10 can also be estimated from the frequency of the input voltage of the VCO.

  As described above, by supplying the input voltage data of the VCO to the drive waveform adjusting circuit 42, it is possible to further improve the accuracy of detecting the angular velocity.

  The present invention can be used in the automobile manufacturing industry, the automobile parts manufacturing industry, and the like.

DESCRIPTION OF SYMBOLS 1 Angular velocity detection apparatus 10 Vibrator 20 Drive circuit 22 Excitation displacement detection circuit 24 Gain control circuit 26 PLL circuit 28 Frequency divider 30 Sensor displacement detection circuit 32 Synchronous detection circuit 34 Integrator 40 Temperature sensor 42 Drive waveform adjustment circuit 44 Booster circuit 44A External power supply 44B Operational amplifier 44C Switch

Claims (2)

A vibrator to be vibrated,
Drive means for outputting a drive signal for exciting and vibrating the vibrator;
Detecting means for detecting displacement in a direction different from the excitation vibration in the vibrator;
An angular velocity detection device comprising: angular velocity detection means for detecting an angular velocity around a direction orthogonal to both the direction of the excitation vibration and the direction of displacement detected by the detection means based on the displacement detected by the detection means. Because
Temperature detecting means for detecting temperature,
The drive means changes the mode of the drive signal according to a change in temperature detected by the temperature detection means,
Angular velocity detector. The drive means is means for changing at least one of an amplitude, a limit value of amplitude, and a bias of the drive signal in response to a change in temperature detected by the temperature detection means.
The angular velocity detection device according to claim 1.

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