JPH05215555A - Vibrating gyro - Google Patents

Abstract

PURPOSE:To obtain a compact and highly accurate gyro by oscillating a vibrating means with an excitation coil and a ferromagnetic piece with approximately resonant frequency in an X-axis direction, detecting displacement in a Y-axis direction and calculating an input angle speed from them. CONSTITUTION:A vibrating gyro 10 is equipped with a displacement detecting means 18 comprising a base 12, a vibrator 14, an oscillating means 16 and a photoelectric encoder. The oscillating means 16 has a ferromagnetic cylinder 24, an excitation coil 26 and a ferromagnetic piece 28. When the coil 26 is magnetized with predetermined intervals, magnetic force is generated on the cylinder 24 so that it is attracted toward the ferromagnetic piece 28 periodically. The magnetization period of the coil 26 is adjusted to close to resonant frequency of the vibrator 14 and vibration is forced in an X-axis direction. Then a known angle speed is input, an output waveform of the coil 26 is compared with a Y-axis direction vibrating waveform generated by Corioli's force and vibrating speed is adjusted to be at a constant value. Thus when an unknown angle speed is input, the angle speed can be detected by measuring amplitude of the vibration in the Y-axis direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibrating gyro, and more particularly to an improvement of a vibrating gyro which obtains an angular velocity from Coriolis force acting in a direction orthogonal to a vibrating direction of a vibrating means.

[0002]

2. Description of the Related Art Conventionally, a gyro has been used only for a special purpose such as a ship or an aircraft, but in recent years, it has also been used for a navigation system for a private car or a self-propelled robot that does not require a track. It is like this.
These systems integrate the output of the gyro to determine the azimuth, integrate the moving speed to obtain the moving distance, and grasp the current position based on the azimuth and the moving distance. Will also be accumulated. For this reason, gyros used in these fields are required to have extremely high angular velocity detection functions as well as severe conditions such as small size, low price, and high durability, and it is an urgent need to develop a gyro that meets these requirements. ..

As a gyro, those based on various principles have been developed, but a so-called vibration gyro or tuning fork gyro has been drawing attention due to its high angular velocity detection sensitivity and the like (Japanese Patent Publication No. 2-57247). .. This vibrating gyro is an application of a phenomenon in which when a rotating angular velocity is applied to a vibrating object, a Coriolis force acts in a direction perpendicular to the vibrating object. Then, generally, a piezoelectric element or the like is attached to the vibrator, and a voltage is periodically applied to the driving piezoelectric element to vibrate the vibrator in a certain direction, and in a direction orthogonal to the vibration direction of the vibrator. The displacement amount of is detected by a separate detection piezoelectric element.

[0004]

However, although the theoretical angular velocity detecting mechanism of the vibration gyro itself is extremely excellent, the standard adjustment of the driving or detecting piezoelectric element, the bonding accuracy, the hysteresis characteristic, etc. Therefore, it has a great influence on vibration control or displacement detection, and it is difficult to obtain a large number of vibration gyros with high accuracy at low cost. The present invention has been made in view of the above-mentioned problems of the prior art, and an object thereof is to provide a vibration gyro having a simple structure and a small size, high angular velocity detection sensitivity, and high accuracy.

[0005]

In order to achieve the above object, a vibrating gyroscope according to the present invention includes a vibrating means, a vibrating means, a displacement detecting means, and an angular velocity calculating means. The vibrating means is erected on the base. Further, the vibrating means is cylindrically wound so as to have a ferromagnetic body portion provided in the vibrating means and an axial center coaxial with the axial center of the vibrating means, and A ferromagnetic body part having an exciting coil arranged in the vicinity of the periphery thereof and a ferromagnetic body piece arranged in the vicinity of the ferromagnetic body part, the ferromagnetic body part being generated by periodically flowing an exciting current in the exciting coil. And a magnetic force between the ferromagnetic pieces applies a vibrating force in the X-axis direction to the vibrating means.
The displacement detecting means detects the displacement of the vibrating means in the Y-axis direction. The angular velocity calculating means calculates the angular velocity from the displacement amount of the displacement detecting means in the Y-axis direction.

[0006]

Since the vibrating gyroscope according to the present invention has the above-mentioned means, the vibrating means forcibly vibrates the vibrating means in the X-axis direction at its substantially resonance frequency. When the angular velocity ω is input in this state, Coriolis force Fc corresponding to the angular velocity ω is generated in the Y-axis direction, and the vibrating means vibrates in the Y-axis direction. Therefore, the Coriolis force F corresponding to the input angular velocity ω
By detecting the displacement in the Y-axis direction generated by c with the displacement detecting means, the angular velocity calculating means can output the input angular velocity ω.

As described above, in the vibrating gyroscope according to the present invention, the driving piezoelectric element or the like is not attached to the vibrating means itself,
Does not affect vibration. Therefore, extremely accurate angular velocity detection can be performed. Further, since the vibrating means is wound in a cylindrical shape having an axis coaxial with the axis of the vibrating means, the vibrating gyro can be miniaturized with a compact structure.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a vibrating gyroscope according to an embodiment of the present invention. FIG. 1A is a side sectional view and FIG. 1B is a front sectional view. A vibrating gyroscope 10 shown in FIG. 1 includes a base 12, a vibrator 14 as a vibrating unit standing on the base 12, and a vibrating unit 16 for vibrating the vibrator 14.
And a displacement detecting means 18 including a photoelectric encoder. A cylindrical housing 20 is installed on the base 12, and the housing 20 supports the displacement detecting means 18 at its upper end.

The vibrator 14 is formed in the shape of a round bar, and the resonance frequencies in the X and Y directions are substantially the same. A movable scale 22 is provided on the upper end of the vibrator 14. Further, the vibrating means 16 is formed into a cylindrical shape so as to have a ferromagnetic cylinder 24 formed in a stepped cylindrical shape having a T-shaped cross section and an axial center coaxial with the axial center of the vibrator 14. Winding excitation coil 26 and ferromagnetic piece 28 formed in a rectangular parallelepiped
And have. The ferromagnetic tube 24 is fitted on the vibrator 14. Further, the exciting coil 26 is disposed near the lower thin cylindrical portion of the ferromagnetic cylinder 24 and wound around a coil bobbin 21 fixed to the inner wall of the housing 20. Further, the ferromagnetic piece 28
The flat portion is disposed close to the upper thick tubular portion of the ferromagnetic tube 24, and is fitted into the housing 20.

The vibrating gyroscope 10 according to this embodiment is constructed as described above. Next, the angular velocity detecting mechanism will be described with reference to FIGS. 2 and 3. First, as shown in FIG. 2, when the exciting coil 26 is excited in a predetermined cycle (FIG. 3A), a magnetic force is generated in the ferromagnetic tube 24 that is the core of the exciting coil 26, and The tube 24 is periodically attracted to the ferromagnetic pieces 28 (FIG. 3 (B)). Then, the exciting cycle of the exciting coil 26 is adjusted to forcibly vibrate in the X-axis direction at the substantially resonant frequency f of the vibrator 14.

Next, for example, by inputting _a known angular velocity ω _a ,
The output waveform of the excitation coil and the waveform of the amplitude in the Y-axis direction generated by the Coriolis force are compared, and the resonance frequency f and the output of the excitation coil are finely adjusted so that the vibration speed V _x becomes a constant magnitude. (Fig. 3 (C)). On the other hand, when an unknown angular velocity ω is input, Coriolis force Fc corresponding to the angular velocity ω is generated in the Y-axis direction (FIG. 3 (D)). As described above, the resonance frequency f of the vibrator 14 is the same in both the X-axis and Y-axis directions, so the vibrator also vibrates in the Y-axis direction.
As a result, the Coriolis force, that is, the angular velocity ω can be detected by measuring the amplitude of vibration in the Y-axis direction (FIG. 3 (E)).

Next, the vibration control means for controlling the vibration of the vibrator 14 in the X-axis direction will be described. As described above, when the angular velocity ω is applied, the vibrator 14 draws a locus as shown in FIG. On the other hand, the angular velocity ω is the velocity V in the Y-axis direction.
It is proportional to y (maximum velocity point = point where Y-axis amplitude becomes zero). Since Vy is also proportional to Vx (velocity in the X-axis direction), if Vx is controlled to be constant, the angular velocity ω will be proportional to only the change in Vy. Here, the distance X from the origin of the vibrator 14 and the velocity V are respectively expressed by the following equation 1.

[0013]

X = Px · sin2πf · t V = dX / dt = 2πf · Px · cos2πf · t Px: maximum amplitude, f: frequency, t: time.
From the above formula 1, the maximum speed is cos2πf · t = 1 or −
When 1, Vx = 2πf · Px. Also, the frequency f
Is constant, it is sufficient to control only the amplitude Px to be constant.

Therefore, as shown in FIG. 5, a feedback control mechanism is adopted as the vibration control means 30 according to the present embodiment, and is composed of a D / A converter 32, a calculator 34, a pulse width modulator 36, and an oscillator 38. There is. The X-direction amplitude detected by the X-axis encoder 18a is D / A.
The analog signal is converted by the converter 32 and compared with the target amplitude value 40 by the calculator 34. Then, the comparison result is input to the pulse width modulator 36, and the pulse width is feedback-controlled so that the target amplitude value and the actually measured amplitude value match. The oscillation frequency of the pulse width modulator 36 is the oscillator 3
8 and is kept constant (resonance frequency).

Next, the angular velocity calculation means used in the present invention will be described. As shown in FIG. 6, the angular velocity calculation means 50 according to this embodiment includes a counter 52 and a multiplier 5.
Including 4. Then, the Y-direction amplitude input from the Y-axis encoder 18b is digitized by the counter 52, and further multiplied by the fixed constant A by the multiplier 54. Since the angular velocity ω is proportional to the amplitude in the Y direction, the multiplication value becomes the angular velocity ω by appropriately adjusting the fixed constant A. In the present invention, since the angular velocity ω is obtained by measuring the amplitude in the Y-axis direction as described above, even if a low frequency disturbance is superposed as shown in FIG.

Next, the displacement of the present invention will be described with reference to FIGS.
The detection means 18 will be described. FIG. 8 shows this embodiment.
Of a photoelectric encoder used as a displacement detection means
A vertical sectional view showing the basic structure is shown, and FIG.
FIG. 8 is a sectional view taken along line XIII-XIII. In the figure
The photoelectric encoder 18 is fixed to the movable scale 22.
Detects the relative movement of both scales, including scale 60
It is something. On the upper surface of the fixed scale 60 in FIG.
Light emitting elements 62 and eight light receiving elements 64a, 64b,
... 64h is arranged. Light emitting element 62 and each light receiving element
The lead wire of the child 64 is fixed to the printed circuit board 66.
It The movable scale 22 has a first grating shown in FIG.
68 is provided, and the first lattice 68 has a matrix-like length.
Rectangular island reflection grating 70₁₁, 70₁₂… 70_1n, 70 2₁，
70_{twenty two}… 70_2n, ..., 70_m1, 70_m2, ... 70_mnincluding
It consists of a reflective grating. In the direction of the X-axis (row) of the lattice part 70
Lined up is pitch P parallel to Y axis₁The lattice part, and the lattice part
The arrangement of 70 in the Y-axis (row) direction is the pitch P parallel to the X-axis.
₁'Constitute the lattice.

On the other hand, the fixed scale 60 has a second grating 72 and third gratings 74a, 74, as is apparent from FIG.
b, ... 74h. The second grating 72 has a triangular transmission grating portion 76 corresponding to the light emitting element 62.
It is composed of a transmission type grating including a, 76b, ... 76d. , 74h are transmission gratings corresponding to the light receiving elements 64a, 64b ,. Therefore, the light L emitted from the light emitting element 62 is reflected by the first grating 68 via the second grating portions 76a, 76b, ... 76d, and the reflected light is the third gratings 74a, 74b ,.
The light is received by the light receiving elements 64a, 64b, ... 64h via h.

As described above, in the photoelectric encoder used in this embodiment, the second grating portions 76a and 76b and the first grating portion 68 are arranged in the column direction and The three grating portions 74a, 74b, 74c, 74d and the light receiving elements 64a, 64b, 64c, 64d each function as a three grating type displacement detector. Further, with respect to relative movement in the Y direction, the second lattice portions 76c, 76d, the first lattice portion 68 are arranged in the row direction, and the third lattice portions 74e, 74f, 7 are arranged.
4g and 74h each function as a three-lattice type displacement detector.

That is, the three-grating type displacement detector detects the amount of displacement by the change in the overlapping of three gratings as shown in FIG. 12 (Journal of the optical societ).
y of America, 1965, vol.55, No.4, p373-381). 12
The three-grating type displacement detector shown in FIG. 2 includes a second grating 72 and a third grating 74 arranged in parallel, a first grating 68 arranged in parallel so as to be relatively movable between the two gratings 72, 74, and the second grating. It includes a light emitting element 62 arranged on the left side of the grating 72 in the drawing, and a light receiving element 64 arranged on the right side of the third grating 74 in the drawing. Then, the light emitted from the light emitting element 62 reaches the light receiving element 64 via the second grating 72, the first grating 68, and the third grating 74, and the light receiving element 64 has the respective gratings 72, 68, 74.
The photoelectric conversion of the illumination light limited by the
Amplify with to obtain a detection signal s.

Here, when the first grating 68 moves relative to the second grating 72 and the third grating 74, for example, in the x direction, the gratings 72, 6 of the illumination light from the light emitting element 62 are moved.
The amount of light blocked by 8, 74 gradually changes, and the detection signal s is output as a substantially sine wave. The pitch P ₁ of the first grating 68 corresponds to the wavelength P of the detection signal s, and the first grating 68 is determined from the wavelength of the detection signal s and its division value.
The relative movement amount of is measured. Therefore, the second grating 72 and the third grating 7 are attached to the movable scale 22 of the first grating 68.
By installing 4 on the fixed scale 60 respectively,
The relative movement amount of both moving members can be detected. Then, in the present embodiment, X of the lattice portion 70 of the first lattice 68 is
The arrangement in the axial direction constitutes a lattice having a pitch P ₁ parallel to the Y axis, and the arrangement of the lattice portions 70 in the Y axis direction constitutes a lattice having a pitch P ₁ ′ parallel to the X axis. Further, the grating portions 76a and 76b of the second grating 72 are formed with gratings parallel to the Y axis and having a pitch P ₂ and the grating portions 76c and 76d are formed with gratings parallel to the X axis and having a pitch P ₂ ′. There is.

Further, the third lattice 74a has an Ax phase lattice, the third lattice 74b has an Ax 'phase lattice, and the third lattice 7
4c has a Bx phase lattice, the third lattice 74d has a Bx ′ phase lattice formed at a pitch P ₃ parallel to the Y axis, and the third lattice 74e has an Ay phase lattice and a third lattice. 74
A lattice for Ay ′ phase is formed on f, a lattice for By phase on the third lattice 74g, and a lattice for By ′ phase on the third lattice 74h are formed in parallel with the X axis at a pitch P ₃ ′. .. Therefore,
When Ax = 0 °, Ax ′ = 180 ° (1 / 2P ₃ different) Bx = 90 ° (1 / 4P ₃ different) Bx ′ = 270 ° (3 / 4P ₃ different) Ay = When O °, '(different Ay 1 / 2P ₃₎ = 180 °' to Ay By a = 90 ° (1 / 4P ₃ 'differs) By a' = 270 ° (3 / 4P ₃ 'differs) and so as Is graduated. As a result, from the light receiving elements 64a, 64b, 64c, 64d, respectively, π
Ax phase, Ax 'phase, Bx phase, Bx' that are out of phase by 1/2
A phase signal can be obtained, and an Ax phase output differentially amplified by the Ax phase-Ax 'phase and a Bx phase output differentially amplified by the Bx phase-Bx' phase are obtained. And the A
Discrimination is made in the relative movement direction of the scale in the X direction based on the phase shift direction of the x-phase output and the Bx-phase output, and the detection signal is electrically divided to detect the displacement amount with high resolution.

On the other hand, the light receiving elements 64e, 64f, 64g,
From 64h, Ay phase with phase shift of π / 2 each,
Ay′-phase, By-phase, and By′-phase signals can be obtained, and the phase discrimination and relative movement distance of the scales 22 and 60 in the Y direction can be detected in the same manner as in the X direction.

As described above, according to the displacement detecting means 18 used in this embodiment, the movement direction and the movement distance in the X direction and the Y direction can be detected by one photoelectric encoder. The X-axis direction detecting gratings and the Y-axis direction detecting gratings may have the same pitch as the corresponding gratings, but different pitches are required when different accuracy is required for each direction. It is also suitable. As described above, according to the vibrating gyroscope of this embodiment, the vibrator 14
Can have an extremely simple configuration, and since it is not required to attach a piezoelectric element or the like, the error can be reduced. Moreover, since the amplitude of the vibration in the X-axis direction is controlled by using a photoelectric encoder that is not in contact with the vibrator and the amplitude in the Y-axis direction is detected by the same encoder, the angular velocity ω is obtained. It is possible to measure ω with high resolution and high accuracy.

Further, since the exciting coil 26 is wound around the coil bobbin 21 fixed to the inner wall of the housing 20 as a vibrating means, a compact structure can be realized without protruding from the housing 20. In the above-mentioned embodiment, the shape of the ferromagnetic cylinder is a stepped cylinder, but the shape of the upper part of the stepped cylinder, that is, the part where the measuring surface is close to the ferromagnetic piece is shown in FIG. The octagonal tubular shape shown in A) or the regular square tubular shape shown in FIG. Further, although the vibrating means is provided in the vicinity of the upper portion of the vibrator in the above-mentioned embodiment, the vibrating means shown in FIG. It is also possible to provide.

In the above embodiment, the housing 2
It is preferable that the coefficient of linear expansion of 0 and the vibrator 14 are substantially equal. That is, when the linear expansion coefficients of the housing 20 and the vibrator 14 are significantly different, the movable scale 2 is affected by temperature change.
This is because the gap between 2 and the fixed scale 60 may change, which may increase the measurement error. In addition, the inside of the housing 20 should be of a closed structure and filled with an inert gas such as helium,
Alternatively, a vacuum is suitable. That is, there is a possibility that the vibration of the vibrator 14 may be affected by the change in atmospheric pressure inside the housing 20.

In the above embodiment, the exciting coil 2
Although the voltage applied to 6 is pulsed, for example, as shown in FIG.
A sinusoidal voltage may be applied as shown in (A). In this case, make the sawtooth voltage synchronized with the sine wave voltage,
The phase is confirmed at t ₀ and t ₂ , and the amplitude in the Y-axis direction is read at t ₁ and t ₃ . In addition, although the columnar vibrator is used in the above-described embodiment, for example, the cylindrical shape shown in FIG. 16A, the regular square shape shown in FIG. 16B, and the regular square tube shown in FIG. It is also possible to adopt a shape, an octagonal shape, or the like.
The oscillator is required to have substantially the same moment of inertia about the X axis and moment of inertia about the Y axis, and to have substantially the same resonance frequency f. Furthermore, the shape of the vibrator is shown in FIG.
It is also preferable to have an upper fine stepped shape as shown in (A), a lower fine stepped shape as shown in (B), or a tapered shape as shown in (C). The oscillator is required to have substantially the same moment of inertia about the X axis and moment of inertia about the Y axis, and to have substantially the same resonance frequency f.

[0027]

As described above, according to the vibrating gyroscope of the present invention, since the vibrator is vibrated in a non-contact manner, it is possible to detect extremely accurate angular velocity with a simple structure. .. Further, since the excitation coil is wound as a vibrating means in a cylindrical shape having an axis coaxial with the axis of the vibrator, the structure is compact and the vibration gyro can be miniaturized.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a schematic configuration of a vibrating gyroscope according to an embodiment of the present invention.

[Fig. 2]

FIG. 3 is an explanatory diagram of an angular velocity measurement principle of the vibration gyro shown in FIG.

[Fig. 4]

5 is an explanatory diagram of vibration control means of the vibration gyro shown in FIG. 1. FIG.

6 is an explanatory diagram of an angular velocity calculation unit of the vibration gyro shown in FIG.

7 is an explanatory diagram of the influence of low-frequency disturbance on the vibration gyro shown in FIG.

[FIG. 8]

[FIG. 9]

FIG. 10

[Fig. 11]

12 is an explanatory diagram of displacement detecting means of the vibration gyro shown in FIG.

FIG. 13 is an explanatory diagram of an example of a ferromagnetic tube.

FIG. 14 is an explanatory diagram of an example of the installation position of the vibrating means.

FIG. 15 is an explanatory diagram of an example of a voltage waveform applied to the excitation coil.

[FIG. 16]

FIG. 17 is an explanatory diagram of an example of a vibrator.

[Explanation of symbols]

 12 Base 14 Vibrator 16 Exciting Means 18 Displacement Detecting Means 24 Ferromagnetic Body Cylinder (Ferromagnetic Body Part) 26 Excitation Coil 28 Ferromagnetic Piece 50 Angular Velocity Calculating Means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Watashi Ishibashi 165 Sakado, Takatsu-ku, Kawasaki City, Kanagawa Prefecture Mitutoyo R & D Co., Ltd.

Claims (1)

[Claims] 1. A vibrating means erected on a base, a ferromagnetic portion provided on the vibrating means, and a cylindrical member having an axial center coaxial with the axial center of the vibrating means. And an exciting coil disposed near the periphery of the ferromagnetic portion and a ferromagnetic piece disposed near the ferromagnetic portion, and the exciting current is periodically applied to the exciting coil. Vibrating means for applying a vibrating force in the X-axis direction to the vibrating means by the magnetic force between the ferromagnetic body portion and the ferromagnetic piece generated by flowing the magnetic field, and displacement for detecting displacement of the vibrating means in the Y-axis direction. A vibrating gyro, comprising: a detection unit; and an angular velocity calculation unit that calculates an angular velocity based on a displacement amount of the displacement detection unit in the Y-axis direction.