JPH07260492A - Angular velocity detector - Google Patents

Abstract

PURPOSE:To increase the amplitude of vibration of a wire for enhancing the sensitivity of a detector detecting Coriolis force, and separate the drive signal of the wire and an angular velosity detection signal in a simple configuration. CONSTITUTION:An angular velosity detector is provided with a pick-up part 2 for detecting Coriolis force generated in a direction at right angle to the vibration of a wire 1 according to the level of angular velocity when the angular velocity is applied around the input shaft of the wire 1 while the wire 1 where a tension is applied is vibrating in a secondary resonance frequency. Then, the wire 1 consisting of a magnetostriction material whose length changes according to magnetic field is used, a coil 3 for drive for generating magnetic filed is installed around the wire 1, and the pickup part 2 detects, without any contact, the vibration displacement generated due to Coriolis force which is generated when the wire 1 is vibrated by the passage of a current of the secondary resonance frequency of the wire 1 for the coil 3 for drive.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angular velocity detection for detecting an angular velocity by detecting the Coriolis force generated according to the magnitude of the angular velocity applied to the wire when the wire is used as the vibrating body. Regarding the device. More specifically, the present invention relates to a vibrating object, that is, when an angular velocity is applied around the longitudinal axis of the vibrating body,
The present invention relates to an angular velocity detecting device for detecting a Coriolis force by using a secondary resonance of a wire as a vibrating body by utilizing a mechanical phenomenon in which a Coriolis force is generated in a direction orthogonal to a vibration direction of the vibrating body. . The main part of this type of angular velocity detecting device is composed of an angular velocity sensor called a vibrating gyro having no rotating body.

In recent years, such an angular velocity sensor has been used, for example, in a navigation system of an automobile, a camera shake preventing device of a video camera, or by changing the state of a suspension of an automobile in accordance with the running state of the vehicle to provide a comfortable ride and stable steering. It is used in a vehicle suspension control system to improve the vehicle performance.

[0003]

2. Description of the Related Art A vibrating gyroscope as used herein has a rotating body that utilizes a mechanical phenomenon that "When angular velocity is applied to a vibrating object, Coriolis force is generated in a direction perpendicular to the vibrating direction." It means no gyro. Research on this vibrating gyro began in the 1950s with a tuning fork type vibrating gyro called "gyrotron" manufactured by Sperry. After that, as a vibrating body, wire, prism,
Although various types such as cylinders have been researched and developed,
The currently available gyros are only tuning fork type gyros manufactured by Tokyo Keiki Co., Ltd. and Watson. For details of the theory of such a tuning fork gyro or a vibration gyro such as a vibration gyro by a wire vibration method, see "Examples".
Will be described in section.

FIG. 6 is a block diagram showing an example of a conventional angular velocity detecting device using a vibration gyro. Here, among various types of vibration gyros, a configuration of an angular velocity detection device having an angular velocity sensor using a wire as a vibrating body (for example, a vibration gyro manufactured by Honeywell) will be exemplified. In FIG. 6, a wire 100 of beryllium copper wire having a predetermined length (for example, 2 inches) is applied by applying an appropriate tension, and the driving magnet 1 is attached to a half of the wire 100.
Place 10 Further, the detection bias magnet 120 is arranged at a right angle to the drive magnet 110 with respect to the remaining half length of the wire 100. Further, a cable 115 is connected to the center of the vibration wire 100 in a direction perpendicular to the wire 100. With such a structure, an angular velocity sensor using a vibration gyro by a wire vibration method is configured.

Further, such an angular velocity sensor is provided with a drive circuit for vibrating the wire 100 and a detection circuit for detecting the Coriolis force generated by applying the angular velocity to the vibrating wire 100. . In addition,
In some cases, the drive circuit and the detection circuit are also referred to as an angular velocity sensor. The drive circuit includes an oscillator 132 that supplies a current having a predetermined frequency to the wire 100, and an amplitude control circuit 130 that adjusts the amplitude of the voltage supplied from the oscillator 132.

On the other hand, the above detection circuit takes out a detection signal from the detection bias magnet 120 and amplifies it, and an output of this detection signal amplifier 134 to a demodulator reference signal. Generator 13
8 has a demodulator 136 that generates a DC voltage of an appropriate level as compared with the output of 8 and a buffer 140 connected to the output side of the demodulator 136.

Here, when the oscillator 132 supplies a current in the mode of the secondary resonance frequency to the vibration wire 100, the wire 100 interacts with the driving magnet 110, as shown in FIG. It vibrates in various modes (shown by hatching in FIG. 6). In the vibration state of this mode,
When an angular velocity is applied as an input about the longitudinal axis (input axis) of the wire 100, the wire 100 is connected to the oscillator 132.
Receives a Coriolis force in a direction perpendicular to the driving vibration direction and vibrates perpendicularly to the driving vibration direction. Since the direction of the magnetic flux of the detection bias magnet 120 is perpendicular to the drive magnet 110, the wire 100 vibrates in the direction crossing the magnetic flux of the detection bias magnet 120 due to the input angular velocity, and the detection bias magnet 120. A current flows in the wire 100 across the portion 120 by the principle of electromagnetic induction. The current value of the current that flows according to this electromagnetic induction principle is
Since it is modulated by the driving frequency from the oscillator 132, it is synchronously rectified by the demodulator 136 and demodulated by the DC voltage. The input angular velocity is detected by evaluating the output voltage value of the demodulated DC voltage.

[0008]

In the angular velocity sensor having the structure shown in FIG. 6, it is necessary to increase the vibration amplitude of the wire 100 in order to increase the sensitivity of the vibration gyro. However, since the angular velocity sensor shown in FIG. 6 has a structure in which a current is passed through the cable 115 itself, as in the case of driving a normal motor, the wire 100 increases as the amplitude of vibration increases. There arises a problem that driving for generating the vibration of 100 becomes difficult.

Further, since the drive cable (cable 115 in FIG. 6) and the angular velocity detection cable are the same, the drive signal of the wire 100 and the angular velocity detection signal may be mixed. To avoid this,
It is necessary to discriminate the wire drive signal and the angular velocity detection signal from each other, and the circuit for extracting the angular velocity detection signal is complicated for such signal discrimination, which causes a problem that the entire circuit becomes expensive. come.

The present invention has been made in view of the above problems, and increases the amplitude of vibration of a wire as a vibrating body to increase the sensitivity of an angular velocity sensor, and at the same time, provides a drive signal for a wire with a wire drive signal. It is an object of the present invention to provide an angular velocity detecting device that can easily separate a detection signal for angular velocity detection.

[0011]

In order to solve the above problems, in the angular velocity detecting device of the present invention, the wire as the vibrating body stretched by applying a predetermined tension vibrates in the mode of the secondary resonance frequency. When an angular velocity is applied around the wire length axis in this state, the magnetic field is detected in order to detect the Coriolis force generated in the direction orthogonal to the vibration direction of the wire according to the magnitude of this angular velocity. A wire is manufactured using a magnetostrictive material whose length changes by, and a driving coil for generating a magnetic field is installed around the wire. further,
The angular velocity detection device of the present invention detects the Coriolis force by causing a current having a secondary resonance frequency of the wire to flow through the drive coil to vibrate the wire in the secondary resonance mode. .

Preferably, the angular velocity detecting device of the present invention is
A pickup unit for detecting the Coriolis force is provided, and the pickup unit is configured to detect the wire in a non-contact manner. Further, preferably, the pickup section includes an arbitrary light emitting element and a light receiving element for receiving light emitted from the light emitting element, and a portion of the wire where vibration displacement due to Coriolis force occurs , Based on the light detected by the light receiving element after transmitting or reflecting the light emitted from the light emitting element,
It is designed to detect angular velocity.

Further, preferably, the above-mentioned pick-up portion is arranged to respond to the vibration displacement of the wire due to the Coriolis force.
A change in the magnetic field generated in a portion magnetized after attaching a magnet to the wire or applying a magnet material is magnetically detected.

[0014]

In the angular velocity detecting device of the present invention, even when the voltage supplied from the oscillator or the like is relatively small, the amplitude of the vibration of the wire of the vibrating body is made relatively large to easily generate the wire vibration. Instead of a conventional drive circuit system for passing a current through a cable, a drive coil (typically an air core coil) for generating a magnetic field is installed around the wire. Further, in the angular velocity detecting device of the present invention, a magnetostrictive material is used as a wire of a vibrating body corresponding to a conventional drive cable, and a current having a secondary resonance frequency of the cable is passed through the air-core coil to resonate the wire, A large resonance can be easily obtained, and the sensitivity of the vibration gyro increases.

Further, as a method of detecting the Coriolis force, by detecting the displacement of the wire in a non-contact manner,
Since a large signal output of the Coriolis component can be obtained, the sensitivity of the vibration gyro can be relatively increased. Thus, in the present invention, a wire made of a magnetostrictive material is used as a vibrating body, and a drive coil such as an air-core coil is installed around the wire as a drive source of this wire, so that the amplitude of vibration of the wire is large. The sensitivity of the vibration gyro increases. Furthermore, since the drive coil is installed away from the wire, it becomes possible to easily separate the drive signal of the wire and the detection signal for angular velocity detection.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the angular velocity detecting device of the present invention will be described in detail below with reference to the accompanying drawings (FIGS. 1 to 4). Figure 1
1 is a block diagram showing a configuration of an angular velocity detecting device according to an embodiment of the present invention.

In FIG. 1, a wire 1 made of a magnetostrictive material having a certain length is stretched by applying an appropriate tension, and a driving coil 3 such as an air-core coil is installed at a half length thereof. . The drive coil 3 is arranged in a state of being spatially separated from the wire 1. Further, the pickup unit 2 is arranged in a portion of the remaining half of the wire 1 so as to be spatially separated from the wire 1. When an angular velocity is applied around the longitudinal axis (input shaft) of the wire 1, the pickup unit 2 is caused by Coriolis force generated in a direction orthogonal to the vibration direction of the wire according to the magnitude of the angular velocity. It is for non-contact detection of displacement of the wire that may occur. If the pickup unit 2 is configured in this way, a large signal output of the Coriolis component can be obtained, so that the sensitivity of the vibration gyro can be relatively increased.

Here, the operating principle of this vibrating gyro will be described in detail. Now, when a mass point of mass m rotates at a constant angular velocity Ω (vector amount) with respect to the inertial coordinate system, the force F acting on the mass point detected by the angular velocity sensor installed in the rotating coordinate system is F = m -(Alpha) -m (ohm) * ((ohm) * r) -2m (ohm) * v (1) It is represented.

The first term on the right side of the equation (1) is the force due to the acceleration α (vector amount), the second term is the centrifugal force (r is the radial vector of the mass point), and the third term is the Coriolis force (v is the mass point). Of the velocity vector). Further, “×” in the equation (1) represents a vector cross product. Now, focusing on only the third term on the right side, the force acting on the mass point is orthogonal to the velocity vector v and the angular velocity vector Ω, and when only the velocity in one axis is given, the Coriolis force is proportional to the angular velocity. It can be said that Therefore, if a vibrating gyro is manufactured so that the first term and the second term on the right-hand side of the equation (1) in the equation (1) can be neglected and a velocity of v can be given to the mass point, this mass point can be acted on. The input angular velocity can be known from the force.

As the velocity v, the vibration velocity is used instead of the linear velocity, and the Coriolis force acting in a plane perpendicular to the vibration velocity and the input angular velocity, or the Coriolis force is springed. A vibration gyro is a device that is received by and is detected as a displacement. Therefore,
As described in FIG. 6, the components of such a vibration gyro include a vibrating body such as a wire, a driving element for driving the vibrating body, and an angular velocity detecting element for detecting the Coriolis force. It consists of elements. Therefore, the vibrating gyro is different from the gyro having a rotating body.
The structure is very simple. Moreover, the vibrating gyro
Since there are no worn parts such as bearings, it is possible to manufacture an inexpensive gyro with a long life. However, since the sensitivity of the vibration gyro is generally lower than that of the gyro having a rotating body, conventionally, it was necessary to increase the amplitude of vibration as described above. In order to deal with this inconvenience, in the embodiment of the present invention shown in FIG. 1, as described above, the wire 1 made of a magnetostrictive material is used as the vibrating body, and the driving source of the wire 1 is an air-core coil or the like around the wire. The driving coil 3 is installed.

Here, referring again to FIG. 1, a drive circuit corresponding to the above-mentioned drive element is based on an oscillator 5 for supplying a current of a predetermined frequency to the wire 1 and a monitor signal output from the oscillator 5. And an amplitude control circuit 4 for adjusting the amplitude of the voltage supplied from the oscillator 5. On the other hand, the detection circuit corresponding to the angular velocity detecting element described above includes the pickup unit 2, the detection signal amplifier 6 for extracting and amplifying the detection signal from the pickup unit 2, and the output of the detection signal amplifier 6. The demodulator (demodulator) has a demodulator 7 that generates a DC voltage of an appropriate level in comparison with the output of the reference signal generator 8, and a buffer 9 connected to the output side of the demodulator 7.

When the oscillator 4 supplies a current in the mode of the secondary resonance frequency to the vibrating wire 1, the wire 1 interacts with the driving coil 3 as shown in FIG. It vibrates in various modes (shown by hatching in FIG. 1). When an angular velocity is applied as an input about the longitudinal axis (input axis) of the wire 1 in the vibration state of this mode, the wire 1 receives the Coriolis force in the direction perpendicular to the driving vibration direction of the oscillator 4, It vibrates perpendicularly to this driving vibration direction. The displacement of the wire due to this vibration is detected by the pickup unit 2 in a non-contact manner. The signal thus detected is amplified by the detection signal amplifier 6 and then demodulator 7 as in the conventional case.
It is synchronously rectified inside and demodulated by DC voltage. The demodulated DC voltage is output via the buffer 9. The input angular velocity is detected by evaluating this output voltage value.

The magnetostriction related to the wire 1 of the present invention will be described. Magnetostriction generally refers to a phenomenon that the outer shape is deformed when a ferromagnetic material or the like is magnetized. The magnetostriction constant λ is defined as follows:
It is represented by δl / l. As the magnetostrictive material, an amorphous metal having a magnetostriction constant λs of about 25 × 10 ⁻⁶ at saturation (for example, “Metgrass 2 manufactured by Allied Signal Co., Ltd.”) is used.
605S-2 ″, which has a fibrous structure) and a permalloy (Ni-Fe) having a magnetostriction constant λs of about 27 × 10 ^−6.
Or a high magnetostriction constant λs of about 800 × 10 ^-6 (the magnetic field is 24
A wire made of a giant magnetostrictive material having a value of 0 kA / m) is used. The composition and manufacturing method of the above-mentioned amorphous metal and permalloy are described in JP-B-55-1.
It is disclosed in Japanese Patent Publication No. 9976.

In particular, as shown in the perspective view of FIG. 2, a wire as a vibrating body (in some cases, referred to as a vibrating wire)
Regarding No. 1, by using a wire rod having a rectangular cross section (width h: thickness b), if the vibration direction of the wire rod is made constant, it is possible to reliably define the unidirectionality of the vibration direction required for the vibration gyro. In addition, the oscillator 5 allows 2
When a current having a frequency that makes the standing wave of the second resonance mode (second harmonic) stand, the vibrating wire vibrates due to the magnetostriction effect, and the standing wave of the second mode is generated in the vibrating wire. When an angular velocity is applied around the input shaft of the wire 1 in the vibration mode of the secondary mode, the wire 1 receives the Coriolis force in the direction orthogonal to the driving direction, and the wire 1 moves in the direction perpendicular to the vibrating direction of the wire 1. Oscillating displacement causes wire 1
Coriolis force is generated in the pickup section 2 of.

Here, one example of the non-contact type pickup unit 2 has an arbitrary light emitting element and a light receiving element for receiving the light emitted from this light emitting element. In this case, the angular velocity is detected based on the light detected by the light receiving element after transmitting or reflecting the light emitted from this light emitting element to the portion of the wire 1 where the vibration displacement occurs. ing. Specifically, a combination of a semiconductor laser and a photodiode can be considered as the light emitting element and the light receiving element.

Further, another example of the non-contact type pickup section 2 is a magnetism detecting means for magnetically detecting the displacement of the magnetic field of the magnetized portion after magnetizing the wire 1 in advance. For example, it is composed of a magnetic sensor such as a magnetoresistive element, a Hall element, or a pickup coil. FIG. 3 is a diagram for explaining a design procedure of the vibrating wire of FIG. 1.

In FIG. 3, an amorphous metal (for example, "Metgrass 2605S-2" manufactured by Allied Signal Co., Ltd.) is used as the type of the wire 1.
Further, the length of the wire 1 (1: L) is set to 3 cm. Further, as shown in FIG. 3, the linear density of the wire 1 is ρ (kg / m) and the moment of inertia of area I is I = (1/1
2) · b · h ³ , the cross-sectional area A is expressed as A = b · h,
The frequency of the second harmonic is expressed as f = ω / 2π = (7.853 / l) ² · (EI / ρA) ^1/2 / 2π (2).

Based on this equation (2), the width h of the wire 1 is
Fig. 3 shows the case of 0.1 mm and the case of 0.5 mm.
As shown, the frequency f of the second harmonic is calculated.
And f = 8.6 MHz and 19 MHz, respectively
Is obtained. However, in any case, the thickness of the wire 1
The thickness b is 25 μm, and the magnetostriction constant λs at saturation is 27 × 1.
0 ^-6, Density is 7.18 kg / mm³, Young's modulus E is 1
30 GPa (= 130 × 10⁹× 0.102 kgf / m
²). In addition, the frequency of such second harmonic
An air-core coil is used to generate vibration.
The value of the frequency of the second harmonic above is the magnetostriction that is usually available.
Considered to be an order that can be easily realized depending on the material
Be done.

Further, the magnetostrictive material used here is an iron-based amorphous metal such as "Metgrass 2605S-2" manufactured by Allied Signal Co., and the saturation magnetic field of this magnetostrictive material is the DC hysteresis loop of FIG. (B-H curve: B represents magnetic flux density and H represents magnetic field)
The value is 0.1 Oe (8 A / m), which is not so high. For comparison, a DC hysteresis loop of cobalt-based amorphous metal is also displayed. The saturation magnetic field of this cobalt-based amorphous metal is lower than that of the iron-based amorphous metal, but since the saturation magnetic flux density (unit is Tesla (T)) is small, the magnetostriction constant λs at saturation is the same as that of the iron-based amorphous metal. It is smaller than amorphous metal.

Further, the number of turns n of the air-core coil required to apply a predetermined saturation magnetic field of 0.1 Oe to the iron-based amorphous metal is calculated. In this case wire 1
It is assumed that a half of the length (1/2 = 1.5 cm) is driven by a current I of 1 A. Here, when the number of turns n is calculated based on the calculation formula of the saturation magnetic field Hs represented by Hs = nI, a value of 12 turns is obtained. That is, if an air-core coil having this number of turns is prepared, the frequency of the second harmonic can be generated in the wire 1.

FIG. 5 is a diagram showing an example of output characteristics of the angular velocity sensor of the present invention. Here, a combination of a semiconductor laser and a photodiode is used as the pickup unit 2 for detecting the angular velocity, and the vibration displacement of the wire 1 is detected by a non-contact method. Since the detected signal is modulated by the frequency for driving the wire, it is necessary to perform synchronous rectification by the demodulator 7 and convert it into direct current. The signal converted into direct current in this way is shown in FIG.
As shown in, the input rotational angular velocity (unit is deg /
It can be taken out from the angular velocity sensor as a direct current output voltage (unit: volt (V)) proportional to (sec). A circle mark on the graph of FIG. 5 indicates a range in which the linearity of the angular velocity sensor is guaranteed. As is clear from FIG. 5, the linearity of the angular velocity sensor having the vibrating wire using the magnetostrictive material of the present invention is guaranteed in a sufficiently wide range.

[0032]

As described above, according to the present invention, a wire made of a magnetostrictive material is used as a vibrating body, and a driving coil such as an air core coil is installed around the wire as a driving source of the wire. Since it is easy to control vibration,
Large vibration amplitude can be obtained. Therefore, the sensitivity of the angular velocity sensor is dramatically increased. Furthermore, since the drive coil is installed away from the wire, it is possible to easily separate the drive signal of the wire and the detection signal for angular velocity detection, which has the advantage of facilitating signal processing.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an angular velocity detecting device according to an embodiment of the present invention.

FIG. 2 is a perspective view showing the configuration of the vibrating wire of FIG.

FIG. 3 is a diagram for explaining a design procedure of the vibrating wire of FIG.

FIG. 4 is a diagram showing a DC hysteresis loop of amorphous metal used in the angular velocity sensor of the present invention.

FIG. 5 is a diagram showing an example of output characteristics of the angular velocity sensor of the present invention.

FIG. 6 is a block diagram showing an example of a conventional angular velocity detection device using a vibration gyro.

[Explanation of symbols]

 1 ... Wire 2 ... Pickup part 3 ... Driving coil 4 ... Amplitude control circuit 5 ... Oscillator 6 ... Detection signal amplifier 7 ... Demodulator 8 ... Demodulator reference signal generator 9 ... Buffer

Claims (9)

[Claims] 1. A wire (1) as a vibrating body stretched by applying a predetermined tension, the wire (1) being vibrated in a mode of a secondary resonance frequency. ), The angular velocity is detected by detecting the Coriolis force generated in the direction orthogonal to the vibration direction of the wire according to the magnitude of the angular velocity when the angular velocity is applied around the longitudinal axis. In the angular velocity detecting device for achieving the above, the wire (1) is made of a magnetostrictive material whose length is changed by a magnetic field, and a driving coil (3) for generating a magnetic field is installed around the wire (1), A current having a secondary resonance frequency of the wire (1) is applied to the drive coil (3) to cause the wire (1) to flow.
The angular velocity detecting device is characterized in that the Coriolis force is detected by vibrating in a secondary resonance mode. 2. The angular velocity detection device according to claim 1, wherein an amorphous metal is used as the magnetostrictive material of the wire (1). 3. The angular velocity detection device according to claim 1, wherein the wire (1) has a fibrous structure. 4. The angular velocity detecting device according to claim 1, wherein an alloy made of ferromagnetic permalloy is used as the magnetostrictive material of the wire (1). 5. The angular velocity detecting device according to claim 1, wherein a giant magnetostrictive material is used as the magnetostrictive material of the wire (1). 6. A wire (1) as a vibrating body stretched by applying a predetermined tension, the wire (1) being vibrated in a mode of a secondary resonance frequency. 1) A pickup unit (2) for detecting a Coriolis force generated in a direction orthogonal to the vibration direction of the wire according to the magnitude of the angular velocity when the angular velocity is applied around the longitudinal axis. ), The wire (1) is made of a magnetostrictive material whose length is changed by a magnetic field, and a driving coil (3) for generating a magnetic field is installed around the wire (1), Caused by the Coriolis force generated when a current having a secondary resonance frequency of the wire (1) is caused to flow through the drive coil (3) to vibrate the wire (1) in a secondary resonance mode, In addition, the vibration direction of the wire (1) is In order to detect the vibration displacement generated in the intersecting direction, the pickup unit (2) detects the wire in a non-contact manner, the angular velocity detecting device. 7. The pickup section (2) includes an arbitrary light emitting element and a light receiving element for receiving light emitted from the light emitting element, and the vibration displacement occurs in the wire (1). The angular velocity detecting device according to claim 6, wherein the angular velocity is detected based on the light detected by the light receiving element after transmitting or reflecting the light emitted from the light emitting element to the portion. 8. The pickup part (2) is magnetized after the magnet is attached to the wire (1), and the picked-up part (2) is responsive to a vibration displacement in a direction orthogonal to a vibration direction of the wire (1). 7. The angular velocity detecting device according to claim 6, further comprising: a magnetic detecting means for magnetically detecting a change in a magnetic field generated in the magnetized portion. 9. The pick-up part (2) is responsive to a portion where the wire (1) is magnetized after being coated with a magnetic material and a vibration displacement in a direction orthogonal to a vibration direction of the wire (1). 7. An angular velocity detecting device according to claim 6, further comprising: a magnetic detecting means for magnetically detecting a displacement of a magnetic field generated in the magnetized portion.