JPH0414734B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vibrating gyroscope that detects angular acceleration by converting displacement generated by Coriolis force into an electrical signal.

The basic sensing element of the gyro generally has a configuration as shown in FIG. That is, the sensing element consists of a columnar metal beam 1 as a vibrating body, one of its main surfaces 1a is driven by a sine wave by a piezoelectric transducer 2a attached to the surface, and its fixed point is a, b are supports 3a, 3
b.

When the beam 1 is vibrated and an angular velocity is applied around the beam's longitudinal axis Z, a force (Coriolis force) that changes sinusoidally at the vibration frequency is applied to the driving surface 1a.
occurs in a direction perpendicular to This force generates vibrations of the same frequency as the drive of beam 1. The vibration induced in the beam 1 by this Coriolis force is detected by a readout circuit (not shown) via a readout piezoelectric transducer 2b attached to a surface 1b perpendicular to the drive surface 1a. Ru.

Note that the Coriolis force is an apparent force that acts only on a moving object in a rotating coordinate system, and if the angular velocity W of the coordinate system with respect to the inertial system is constant, this force is obtained by excluding centrifugal force. Then, if n is the unit vector in the rotational axis direction, m is the mass of the object, and v is the velocity vector seen from the rotational coordinate system, then it is expressed as 2mw [vxn].

Further, a piezoelectric transducer 2c for feedback, which is used to keep the amplitude of the beam 1 constant and excite it at a mechanical resonance frequency, is provided on a surface 1c parallel to the driving surface 1a of the beam 1, and a piezoelectric transducer 2c for feedback is used to keep the amplitude of the beam 1 constant and excite it at a mechanical resonance frequency.
Damping piezoelectric transducers 2d are respectively attached to surfaces 1d parallel to .

[Conventional technology]

Conventional vibrating gyros using sensing elements such as those described above with respect to FIG. It is designed to generate a DC signal proportional to the input angular velocity. This DC signal is provided as a positive full-wave rectified signal when the detection signal and the signal from the feedback piezoelectric transducer are in phase, and is provided as a negative full-wave rectified signal when they are out of phase by 180°. Therefore, the amplitude and polarity of this DC signal indicate the magnitude and direction of the angular velocity input.

[Problem that the invention attempts to solve]

As mentioned above, conventional vibrating gyros detect angular velocity using the magnitude of the DC signal obtained by demodulating a detection signal that is modulated in proportion to angular velocity. In addition to the fact that the detection results are easily affected by various factors, complex signal processing is required to determine the direction of the angular velocity input, which requires complicated circuit configurations.

SUMMARY OF THE INVENTION Therefore, in view of the above-mentioned conventional problems, it is an object of the present invention to provide a vibrating gyroscope that is less susceptible to disturbances and that can easily detect direction.

[Means for solving problems]

In order to achieve the above object, a vibrating gyroscope made according to the present invention includes a columnar vibrating body, a drive piezoelectric transducer attached to a first side surface of the vibrating body, and a driving piezoelectric transducer attached to a first side surface of the vibrating body, and a piezoelectric transducer for driving, which is perpendicular to the first side surface. a readout piezoelectric transducer attached to a second side surface, the readout piezoelectric transducer converts the vibration of the vibrating body driven by the drive piezoelectric transducer into an electrical signal, and A vibrating gyroscope configured to detect angular velocity using an electric signal, comprising phase detection means for detecting a change in phase of the electric signal with respect to a phase of a drive signal that drives the drive piezoelectric transducer,
It is characterized in that the angular velocity is detected based on the change in phase detected by the phase detection means.

[Function] In the above configuration, focusing on the fact that the output of the readout piezoelectric transducer changes not only the amplitude but also the phase depending on the angular velocity, The angular velocity is indirectly detected by detecting the change in the phase of the signal by the phase detection means.

Unlike its amplitude, the phase of the electrical signal generated by the readout piezoelectric transducer does not change due to disturbances such as voltage or temperature changes, and the direction of the angular velocity depends on the direction of phase change relative to the reference phase. can also be easily detected.

〔Example〕

An embodiment of the apparatus according to the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a vibrating gyroscope according to the present invention, in which the same members as those in FIG. 3 are given the same reference numerals.

In the figure, the piezoelectric transducer 2a for driving and the piezoelectric transducer 2c for feedback attached to the beam 1 are attached so that the piezoelectric elements have opposite polarities. Figure 2a on the piezoelectric transducer 2a.
When a drive signal as shown in is applied, the readout and feedback piezoelectric transducer 2
A readout signal and a feedback signal as shown in FIG. 2b, which are 90 degrees ahead of the drive signal in phase, are obtained at the outputs of signals b and 2c, respectively.

10 is a 90° phase shifter provided to make the feedback signal from the feedback piezoelectric transducer 2c in phase with the drive signal, and 12 and 14 are drive signals for driving the drive piezoelectric transducer 2a (see Fig. 2b). ) and the readout signal obtained by the readout piezoelectric transducer 2b (FIG. 2b)
These are waveform shaping circuits that shape the respective waveforms, and pulse signals as shown in FIG. 2c and d are obtained at their outputs, respectively.

16 is a phase comparison circuit that compares the phases of the output pulses of the waveform shaping circuits 12 and 14 and outputs a pulse with a pulse width corresponding to the phase shift, and is composed of, for example, an exclusive OR (EXOR) gate circuit; When comparing the phases of the pulses shown in FIG. 2c and d, a pulse with a duty ratio of 50% is output as shown in FIG. 2e. 18 is a low pass filter (LPF) to which the output pulse of the phase comparator circuit 16 is input and outputs a DC signal with a level corresponding to the pulse width of the output pulse;
In response to the input of the pulse, a level signal of ±0 is output. Then, depending on the increase or decrease in the duty ratio, +
Or outputs a - level signal.

20 is an A/D conversion circuit that converts the analog signal obtained as described above into a digital signal for subsequent signal processing.

By the way, in the above-mentioned vibrating gyroscope, even if the beam is driven in a sinusoidal manner by the drive piezoelectric transducer, in principle, when the angular velocity is 0, no readout signal appears on the readout piezoelectric transducer. . However, in reality, the read piezoelectric transducer outputs a read signal that is slightly out of phase with the drive signal by approximately 90°. This is thought to be because the readout piezoelectric transducer, which is attached to the surface perpendicular to the beam drive surface, receives a force other than the Coriolis force, the so-called leakage force, due to the drive by the drive piezoelectric transducer. .

When an angular velocity is applied around the longitudinal axis Z of the beam, a Coriolis force proportional to the angular velocity is generated in a direction perpendicular to the drive surface, varying sinusoidally in phase with the vibration frequency. Acts on the surface on which the piezoelectric transducer is mounted.

Therefore, a combined force of the Coriolis force and the leakage force acts on the readout piezoelectric transducer mounted on a surface perpendicular to the driving surface. This combined force is
It is represented by a vector that combines the magnitude and phase of Coriolis force and leakage force. Here, the leakage force is not affected by the angular velocity and is always constant, but the magnitude of the Coriolis force changes depending on the magnitude of the angular velocity, so the phase of the resultant vector changes depending on the magnitude and direction of the angular velocity. The phase of the readout signal generated by the readout piezoelectric transducer in response to the combined force changes in accordance with the angular velocity.

In addition, when voltage fluctuations or temperature fluctuations are applied, the magnitude of the Coriolis force changes, so the magnitude of the resultant force changes, but at this time, the magnitude of the leakage force changes in the same way, so the resultant force also changes. The phase of the force does not vary as much as its magnitude.

Therefore, by detecting the angular velocity based on the phase of the readout signal, the detection results are prevented from being greatly influenced by external factors such as voltage fluctuations and temperature fluctuations.

The solid lines a to f in FIG. 2 indicate when the input angular velocity is 0, and when the angular velocity is added in one direction and the readout signal changes as shown by the dotted line in FIG. 2b, the waveform shaping circuit 14 and the phase comparison circuit 16, the output signal of the LPF 18 changes as shown by dotted lines in FIG. 2 d, e, and f, respectively. On the other hand, when an angular velocity in the opposite direction to that described above is applied, the output signals of the readout piezoelectric transducer 2b, waveform shaping circuit 14, phase comparison circuit 16, and LPF 18 are as shown in FIG.
Each of e and f is shown by a dashed dotted line.

That is, the output of the LPF 18 provides signals with opposite polarities depending on the magnitude and direction of the input angular velocity, and the phase advances when rotating clockwise, and lags when rotating counterclockwise. Therefore, there is no need to provide special means for determining rotation, and the circuit configuration becomes simple.

In particular, even if the amplitude of the read signal, that is, the output signal changes due to fluctuations in the power supply voltage, the phase hardly changes, so changes in the input angular velocity can be detected with high accuracy.

〔Effect of the invention〕

As explained above, according to the present invention, the angular velocity is detected by detecting the change in phase of the electrical signal generated by the readout piezoelectric transducer, which is not easily affected by power supply voltage fluctuations or disturbances, with respect to the reference phase. Therefore, many effects such as being able to detect angular velocity with high precision and easily determining the direction of angular velocity based on the direction of the change in phase can be obtained.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the vibrating gyroscope according to the present invention, Fig. 2 is a waveform diagram showing signal waveforms of each part in Fig. 1, and Fig. 3 is a diagram for explaining the principle of the vibrating gyroscope. FIG. DESCRIPTION OF SYMBOLS 1... Beam, 2a... Piezoelectric transducer for drive, 2b... Piezoelectric transducer for readout, 16... Phase comparison circuit.

Claims (1)

[Scope of Claims] 1. A columnar vibrating body, a drive piezoelectric transducer attached to a first side of the vibrating body, and a readout attached to a second side perpendicular to the first side. a piezoelectric transducer for driving, the vibration of the vibrating body driven by the piezoelectric drive transducer is converted into an electrical signal by the piezoelectric readout transducer, and the angular velocity is detected by the electrical signal. The vibrating gyro according to the present invention includes a phase detection means for detecting a change in the phase of the electric signal with respect to a phase of a drive signal that drives the piezoelectric transducer for driving, and based on the change in phase detected by the phase detection means. A vibrating gyroscope that detects angular velocity.