JPS61193019A - Oscillating gyro - Google Patents

Abstract

PURPOSE:To make it difficult to be influenced by disturbance and to perform direction detection simply by detecting the angular velocity based on the phase detected by a phase detecting means. CONSTITUTION:A piezoelectric transducer 2a for driving and a piezoelectric transducer 2b for feedback adhered to a beam 1 are fitted so that piezoelectric elements are made reversed polarity. Hereby, when a driving signal is impressed on the transducer 2a, a readout signal and a feedback signal with the phase going ahead 90 deg. than the driving signal are obtained with the outputs of the piezoelectric transducers 2b and 2c for readout and feedback. Then, the feedback signal is made in-phase with the driving signal by a 90 deg. phase shifter 10 and the readout signal is waveform-shaped respectively by waveform shaping circuits 12 and 14 to output pulse signals. These output pulse signals are made phase- comparison 16 and made pulses with the pulse width corresponding to the phase shift and made a DC signal via an LPF 18. Then, this DC signal is converted into a digital signal with an A/D converting circuit 20.

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 into an electrical signal.

The basic sensing element of the sensor generally has a configuration as shown in FIG. That is, the sensing element consists of a columnar metal beam l as a vibrating body, and one of its main surfaces 1
A is driven in a sinusoidal manner by a piezoelectric transducer 2a attached to the surface, and its fixed points a and b are supported by supports 3a and 3b, respectively.

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

Note that Coriolis 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. and,
If the unit hector in the rotational axis direction is n, the mass of the object is m, and the velocity vector seen from the rotational coordinate system is V, then 2mw (
vn).

In addition, a feedback piezoelectric transducer 2d, which is used to keep the amplitude of the beam 1 constant and excite it at a mechanical resonance frequency, is mounted on a surface 1c parallel to the driving surface 1a of the beam 1, and parallel to the surface 1b. A damping piezoelectric transducer 2d is attached to each surface 1d.

[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 of proportional magnitude. This DC signal is provided as a positive full-wave rectified signal when the detection signal and the signal from the piezoelectric transducer for feedback are in phase, and is provided as a negative full-wave rectified signal when they are out of phase by 180 degrees. 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 gyroscopes 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 result is large due to various factors, and it is easy to be affected by problems, complex signal processing is required to know the direction of the angular velocity input, and the circuit configuration for this becomes complicated.

[Means for solving problems]

The present invention aims to eliminate the above-mentioned problems of the conventional ones and provide a vibrating gyroscope that is less susceptible to disturbances (and can easily detect direction). , a driving piezoelectric transducer attached to a first side surface of the vibrating body, and a readout piezoelectric transducer attached to a second side surface perpendicular to the first side surface, the driving piezoelectric transducer In the vibrating gyroscope, the vibration of the vibrating body driven by the piezoelectric transducer is converted into an electric signal by the readout piezoelectric transducer, and the angular velocity is detected from the electric signal. Phase detection detects a change in phase of the electric signal. This is accomplished by a vibrating gyroscope characterized in that it is equipped with a means for detecting an angular velocity based on the phase detected by the phase detecting means.

[For production]

The present invention detects angular velocity not by using amplitude, which changes according to angular velocity, but by using phase, which changes simultaneously with amplitude but does not change due to disturbances such as voltage or temperature changes. In the case of detection based on this phase, it is possible to easily generate positive or negative signals depending on the delay or lead with respect to the reference phase by phase comparison.

〔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 driving piezoelectric transducer 2a and the feedback piezoelectric transducer 2b attached to the beam l are attached so that the piezoelectric elements have opposite polarities. When a drive signal as shown in Figure 2 is applied, the output of the readout and feedback piezoelectric transducers 2b and 2C is a readout signal and A feedback signal is obtained respectively.

10 is a 90° phase shifter provided to make the feedback signal from the feedbank piezoelectric transducer 2C in phase with the drive signal, and 12.14 is a drive signal for driving the drive piezoelectric transducer 2a (FIG. 2(b)). and a waveform shaping circuit that shapes the readout signal (FIG. 2(b)) obtained by the readout piezoelectric transducer 2b.
Pulse signals as shown in each are obtained.

Reference numeral 16 denotes 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.
2 (C)
When comparing the phases of the pulses shown in , fdl,
As shown in FIG. 2, a pulse with a tuteity ratio of 50% is output. 18 is a low-pass filter (LPF) which receives the output pulse of the phase comparison circuit 16 and outputs a DC signal with a level corresponding to the pulse width of the output pulse; When the duty ratio increases or decreases, a level signal of 10 or -0 is output.

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

The vibrating angular velocity sensor of the present invention described above outputs a readout signal with a phase shift of 90° to the readout piezoelectric transducer when the angular velocity is O, and that the magnitude of the angular velocity input is This was done by focusing on the fact that the phase of the readout signal and the amplitude change in opposite directions depending on the direction of the signal.

Figure 2 (al~(fl) The solid line indicates when the input angular velocity is O. When the angular velocity is applied in one direction and the readout signal changes as shown by the dotted line in Figure 2 [bl], the waveform shaping circuit 1
4. Phase comparison circuit] 6. The output signal of LPF l 8 changes as shown in the dotted lines in Figure 2 (dl, tel, (fl).On the other hand, when an angular velocity in the opposite direction to that described above is applied includes a readout piezoelectric transducer 2b, a waveform shaping circuit 14, a phase comparison circuit 16, and an LP.
The output signals of F18 are shown in Fig. 2 (1) l, (dl, (
e) and (fl are each 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 the phase of the readout signal, which is less susceptible to power fluctuations and disturbances, so that it is possible to detect the angular velocity with high precision, and also easily determine the direction of the angular velocity. Many effects can be obtained, such as the ability to

[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 showing 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. Procedural amendment (voluntary) July 1985 298 1, 8 indications 1985 Patent registration application No. 32
No. 887 No. 2, Title of the invention: Vibrating gyroscope 3, Relationship to the amended case Patent applicant address: 1-4-28 Mita, Minato-ku, Tokyo
Formula 6 % 4, Specification page 7, line 6' (EX, 0R) J'
Correct to EX ORJ. 5, Akira, Book 11II, page 7, line 19, "Vibration type angular velocity sensor of the present invention" is corrected to "Vibration type angular velocity sensor of the present invention". that's all

Claims (1)

[Claims] A columnar vibrating body, a driving piezoelectric transducer attached to a first side of the vibrating body, and a readout piezoelectric transducer attached to a second side perpendicular to the first side, the driving In the vibrating gyroscope, the vibration of the vibrating body driven by the readout piezoelectric transducer is converted into an electric signal by the readout piezoelectric transducer, and the angular velocity is detected from the electric signal, and a change in the phase of the electric signal is detected. What is claimed is: 1. A vibrating gyroscope comprising: a phase detecting means, and detecting an angular velocity based on the phase detected by the phase detecting means.