JPH049708A - Angular velocity detector - Google Patents

Abstract

PURPOSE:To obtain the correct angular velocity by providing a second sound pressure detecting means for directly detecting the pressure of the sound generated from a vibrating plate, and comparing/correcting an output of a first sound pressure detecting means on the basis of the signal of the second sound pressure detecting means. CONSTITUTION:When a vibrating plate or diaphragm 2a of a speaker 2 is driven by an oscillator 8, there is brought about the pressure difference between the air chambers 5, 6 in a casing 1. As a result, the air begins to flow in an acoustic propagation path 7, generating the pressure difference within the acoustic propagation path 7. The pressure signal is detected by first sound pressure detecting means 3, 4, and sent to a signal processing circuit 9, where the signal is converted to a sensor output. The pressure of the sound generated from the diaphragm 2a is directly detected by a second sound pressure detecting means 12 and sent to the circuit 9 as a reference signal for correction. Based on the outputs from the detecting means 3, 4, 10, the circuit 9 detects the rotating angular velocity around a virtual shaft orthogonal to the propagation path 7. Since the pressure of the sound generated in front of the speaker 2 is detected directly by the detecting means 10 to be used as a reference signal for correction, the sensor outputs of the detecting means 3, 4 can be corrected, whereby the correct angular velocity can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an acoustic gyro type angular velocity detection device suitable for use in detecting angular velocity.

(Prior Art) Conventionally, as this type of angular velocity detection device, the one described in US Pat. No. 2,999,389, for example, is known. To explain this based on FIG. 7, numeral 30 is an oscillator as a sound pressure generating means, and this oscillator 30 drives a speaker 31, and a standing wave 33 is generated inside the case 32.
to occur.

Further, 34 is a wave node formed by the standing wave 33,
At a position corresponding to the node 34 in the case 32'2, there is a pair of conduits 35. for sound pressure detection. 36 is attached and conduits 35,36 are connected to a differential pressure microphone 37. Note that 38 is an amplifier that amplifies the output of the differential pressure microphone 37, and 39 is a rectifier.

In this angular velocity detection device, when no angular velocity is applied to the case 32, the sound pressures detected through the two conduits 35 and 36 are equal, and the detection value of the differential pressure microphone 37 is zero. On the other hand, when an angular velocity in the direction of arrow W is applied to case 32, Y
A Coriolis force is generated in the axial direction, which causes the sound pressures detected through the two conduits 35, 36 to be different.

Therefore, by detecting this sound pressure difference with the differential pressure microphone 37, the magnitude of the angular velocity in the W direction applied to the case 32 can be detected.

However, in the above angular velocity detection device, since the sound pressure difference is detected using only the air chamber on the front side of the speaker, the output of the sound pressure difference detected by the differential pressure microphone 37 is small, and it is difficult to obtain the desired detection accuracy. It's becoming difficult. Moreover,
Since loud noise is generated from the rear side of the speaker 31,
Special soundproofing measures must be taken.

Therefore, in recent years, an improved type of the above-mentioned angular velocity detection device that does not utilize standing waves has been developed. This improved type will be explained based on FIGS. 8(A) to 8(C). By driving the speaker 2 with the oscillator 8, a pressure difference is generated between the two air chambers 5. The acoustic propagation path 7 is configured to generate air flow through an acoustic propagation path 7 consisting of a slit with a rectangular cross section that communicates between the acoustic propagation paths 7 and 6. As a result, a pressure difference also occurs within the acoustic propagation path 7. Here, as shown in FIG. 8(B), sound pressure detection means 3 and 4 consisting of two microphones are attached to the cross section 2 that cuts the acoustic propagation path 7 vertically. Pressure detection means 3, 4
The pressure signal from the sensor is sent to a signal processing circuit (not shown) and converted into a sensor output.

Now, when no angular velocity is applied to case 1, no Coriolis force is generated, so the sound pressures detected by the two sound pressure detection means 3 and 4 are equal, and the sensor output value is zero. On the other hand, in the state shown in FIG. 8(C), when an angular velocity is applied to case 1 in the direction of arrow W centering on the virtual central axis l, a Coriolis force is generated on the moving gas particles in case 1, which causes 2 The sound pressures detected by the two sound pressure detection means 3 and 4 are different from each other. Therefore, by signal processing the detected sound pressure difference in a signal processing circuit, it becomes possible to detect the angular velocity.

(Problem to be Solved by the Invention) However, in such a conventional angular velocity detection device, the level of sound pressure generated by the speaker 2 is stable, and the phase relationship between the speaker drive signal and the sound pressure signal is constant. It is configured to detect angular velocity on the assumption that the angular velocity is maintained at . Therefore, if the level or phase of the sound pressure generated in response to the speaker drive signal changes significantly due to changes in the ambient temperature or changes in the characteristics of the speaker 2 itself over time, this will cause an error in the detected value of the angular velocity. There was a problem.

The present invention has been made in view of these conventional problems, and its purpose is to provide an angular velocity detection device that can prevent detection errors due to fluctuations in the level and phase of generated sound pressure.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention provides a sound pressure generating means comprising a speaker and an oscillator that outputs a drive signal to the speaker, and a sound pressure generating means that is isolated by a diaphragm of the speaker. a case having a plurality of air chambers; an acoustic propagation path that communicates the plurality of air chambers; a first sound pressure detection means disposed in the acoustic propagation path; and a first sound pressure detection means disposed at a location of the case facing the air chambers. a second sound pressure detection means for directly detecting the sound pressure generated from the diaphragm; A signal processing circuit connected to the second sound pressure detection means and configured to detect angular velocity by comparing and correcting the output of the first sound pressure detection means with reference to the output of the second sound pressure detection means. It is characterized by

(Function) In this invention, when angular velocity is applied, a pressure difference is generated in the acoustic propagation path and an air flow is formed. Therefore, a change in sound pressure occurs in the acoustic propagation path due to the flow of air, and this change in sound pressure is detected by the first sound pressure detection means and sent to the signal processing circuit. On the other hand, the sound pressure generated from the diaphragm inside the case is directly detected by the second sound pressure detection means and sent to the signal processing circuit.

Then, the signal processing circuit compares the signal of the first sound pressure detection means with the signal of the second sound pressure detection means as a reference, and corrects the output level and phase of the signal according to the result. As a result, even if the output level and phase of the generated sound pressure change due to changes in ambient temperature or the like, it is possible to prevent detection errors in the angular velocity.

(Example) Hereinafter, one embodiment of the present invention will be described based on the drawings.

Figure 1 is an overall configuration diagram showing this embodiment, and Figure 2 is the first
FIG.

First, to explain the configuration, 1 is a case of an acoustic gyro type angular velocity detection device, and inside the case 1, a vibration wave is generated by a sound pressure generating means, and the sound pressure generating means is connected to a speaker 2 and a speaker thereto. It consists of an oscillator 8 that outputs a drive signal.

The inside of the case 1 is separated into an air chamber 5 and an air chamber 6 by the diaphragm 2a of the speaker 2 and its support member 12, and these air chambers 5 and 6 are separated by an acoustic propagation path 7 formed by a slit or the like.
It is connected by As shown in FIG. 2, first sound pressure detection means 3 and 4 consisting of microphones are attached to opposite ends of the second part of the acoustic propagation path 7, and A second sound pressure detection means 10 consisting of a microphone is attached to the center of the front wall so as to face the front of the diaphragm 2a. These sound pressure detection means 3, 4
．． A signal processing circuit 9 that receives and processes these output values is connected to 10, and is configured to detect the angular velocity based on these output values.

Next, the operation of the embodiment will be explained.

First, by driving the diaphragm 2a of the speaker 2 with the oscillator 8, a pressure difference is generated between the two air chambers 5.6 in the case 1, and an air flow is formed in the acoustic propagation path 7.

This causes a pressure difference within the acoustic propagation path 7, and this pressure signal is detected by the first sound pressure detection means 3, 4, sent to the signal processing circuit 9, and converted into a sensor output. On the other hand, at the same time, the sound pressure generated from the diaphragm 2a in the air chamber 6 is directly detected by the second sound pressure detection means 12 and sent to the signal processing circuit 9 as a reference signal for correction. Then, in the signal processing circuit 9, the first and second sound pressure detection means 3.4
．． Based on the output from 10, the rotational angular velocity around the interplate axis perpendicular to the acoustic propagation path 7 is detected.

Next, the method of correcting the angular velocity detection described above will be explained in detail.

If the ambient temperature changes now, the gain of the sound pressure generated by the speaker will change significantly. In particular, the elastic modulus of the diaphragm 2a changes between the front side and the rear side of the speaker 2, and the change in gain with respect to temperature differs. Therefore, the sound pressures of the noise components in the vicinity of the mounting position of the first sound pressure detection means 3.4 vary greatly. As a result, unless this is corrected, a value different from the actual angular velocity will be erroneously output due to the change in sound pressure.

Therefore, in this example, in order to prevent such output errors, the sound pressure generated on the front side of the speaker 2 is directly measured by the second sound pressure detection means 10, and the output is used as a reference signal for correction. Accurate angular velocity is detected by correcting the sensor outputs of the sound pressure detection means 3 and 4.

To describe this correction method more specifically with reference to the drawings, the sensor output from the first sound pressure detection means 3 and 4 is
As shown in the figure, it increases or decreases in proportion to changes in ambient temperature. For example, when the temperature drops to 0℃, the sensor output will change to 25℃ at room temperature.
The IV culm becomes smaller than when it was heated, and when it is heated to about 40°C, it becomes larger by about 0.6V. On the other hand, the second sound pressure detection means 1
As is clear from FIG. 4, when the ambient temperature changes, the output waveform of 0 becomes delayed in phase θ and increases in gain with respect to the speaker drive signal at low temperatures.

Conversely, at high temperatures, the phase θ advances and the gain decreases.

Therefore, in this example, the outputs of the first sound pressure detection means 3 and 4 are compared based on the output of the second sound pressure detection means 10, and the reference output gain or reference output phase is calculated according to the comparison result. . Then, based on this calculated value, the outputs of the first sound pressure detection means 3 and 4 are corrected according to equation (1) or (2), and the correct angular velocity is detected from the corrected sensor output value.

Correction output = Output before correction x Jx (reference output gain)...
・・・・・・・・・・・・(1) (However, 1 (1 is a constant) Correction output = Output before correction X (k2X (reference output phase - Φ)
+11 (2) (where k2 is a constant and Φ is a reference phase at room temperature) In this example, the second sound pressure detection means 10 is placed on the front side of the speaker 2. Since it is disposed in the center, the sound pressure generated from the diaphragm 2a can be measured with high sensitivity.

Although the embodiments have been described above, the present invention is not limited thereto, and various embodiments can be considered.

For example, in the embodiment, the second sound pressure detection means 10 is attached to the front side of the speaker 2, but this attachment position is a point where the sound pressure generated from the diaphragm 2a can be well measured without being affected by the angular velocity. If so, the rear side of speaker 2 or the fifth
It is also possible to install it at a midpoint between the first sound pressure detection means 3 and 4 near the center of the acoustic propagation path 7 as shown in FIGS.

In addition, in the embodiment, two first sound pressure detection means 3 and 4 are provided above the acoustic propagation path 7, but one of them is omitted and the signal from the other first sound pressure detection means 3 or 4 is The configuration may be such that the level and phase of the sensor output are corrected by comparing the signal from the second sound pressure detection means 10 with the signal from the second sound pressure detection means 10.

(Effects of the Invention) As described above, according to the present invention, the second sound pressure detection means for directly detecting the sound pressure generated from the diaphragm is disposed in the case, and the 1 sound pressure detection 1
Since the sensor outputs of the two stages are compared and corrected, even if the level or phase of the generated sound pressure changes due to changes in ambient temperature or changes in the characteristics of the speaker over time, this change can be reliably corrected. This has the effect of preventing detection errors and obtaining accurate angular velocity.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram of an angular velocity detection device showing an embodiment of the present invention, Fig. 2 is a view taken in the direction of the ■ arrow in Fig. 1, Fig. 3 is a graph showing the characteristics of sensor output with respect to temperature, and Fig. 4 Diagram (A
), (B), and (C) are waveform diagrams showing the output of the second sound pressure detection means at low temperatures, normal temperatures, and high temperatures, respectively;
Fig. 5 is an overall configuration diagram showing a modified example in which the second sound pressure detection means is attached to the second part of the case, Fig. 6 is a view taken in the direction of the ■ arrow in Fig. 5, and Fig. 7 is an overall diagram showing a conventional example. Configuration diagram, Figure 8 (A)
. (B) and (C) are a side sectional view, a back sectional view, and a plan view showing other conventional examples, respectively. 1... Case 2... Speaker (sound pressure generation means) 2a... Vibration plate 3.4... First sound pressure detection means 5.6... Air chamber 7... Sound propagation path 8... Oscillator 9... Signal processing circuit 10... Second sound pressure detection means Fig. 1 Fig. 2 Patent applicant Nissan Motor Co., Ltd. Agent Patent attorney Kazu]・C) Figure 4 Figure 4

Claims (1)

[Claims] 1. a sound pressure generating means comprising a speaker and an oscillator that outputs a drive signal to the speaker; a case having a plurality of air chambers separated by a diaphragm of the speaker; an acoustic propagation path that communicates the plurality of air chambers; a first sound pressure detection means disposed in the acoustic propagation path; a second sound pressure detection means disposed at a location facing the air chamber of the case to directly detect the sound pressure generated from the diaphragm; a signal processing circuit that is connected to the first and second sound pressure detection means and detects angular velocity by comparing and correcting the output of the first sound pressure detection means with reference to the output of the second sound pressure detection means; An angular velocity detection device comprising: