JP2614550B2 - Vibrating gyro - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, gyros have been used only for special applications such as ships and aircraft, but in recent years, they have also been used for navigation systems such as private automobiles and self-propelled robots that do not require a track. It has become.
These systems integrate the output of the gyro to determine the azimuth, calculate the travel distance by integrating the moving speed, and grasp the current position based on the azimuth and the travel distance. Is also 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 the development of gyros that meet these requirements is urgently required. .

A gyro based on various principles has been conventionally developed, but a so-called vibrating gyro or tuning fork gyro has attracted attention due to its high angular velocity detection sensitivity (Japanese Patent Publication No. 2-57247). . This vibrating gyroscope applies a phenomenon in which when a rotational angular velocity is applied to a vibrating object, a Coriolis force acts in a direction perpendicular to the vibration. In general, a piezoelectric element or the like is attached to the vibrator, and the vibrator is vibrated in a certain direction by periodically applying a voltage to the driving piezoelectric element, and the vibrator is vibrated in a direction orthogonal to the vibration direction of the vibrator. Is detected by a separate detecting piezoelectric element.

[0004]

However, although the theoretical angular velocity detecting mechanism of the vibrating gyroscope itself is extremely excellent, adjustment of the standard of the driving or detecting piezoelectric element, bonding accuracy, hysteresis characteristics, etc. This has a great effect on vibration control or displacement detection, and it has been difficult to obtain high-precision vibration gyros in large quantities at low cost.

An object of the present invention is to provide a vibration gyro having a simple configuration, high angular velocity detection sensitivity, and high accuracy.

[0006]

According to a first aspect of the present invention, there is provided a vibration gyro including a vibration unit, a vibration unit, a displacement detection unit, a vibration control unit, and an angular velocity calculation unit. The vibration means is erected on the base. The vibrating means is arranged close to the vibrating means, and applies a vibration force in the X-axis direction to the vibrating means by a magnetic force. Displacement detection means includes a movable scale which is installed on the vibrating means includes a movable scale and oppositely disposed fixed scale, its in the X-axis direction and the Y-axis direction of the vibrating means
Detect the amplitude for each. Vibration control means, so that the X-axis direction amplitude inputted from the displacement detecting hand stage is constant
A, performs vibration control before Symbol vibrating means. Angular velocity calculating means solid the Y-axis direction amplitude inputted from the displacement detecting hand stage
It calculates the angular velocity by multiplying by a constant a constant.

[0007]

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 substantially its resonance frequency by the vibrating means. 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 also vibrates in the Y-axis direction. Therefore, the X-axis Direction amplitude detected by the displacement detecting means, if further control of the X-axis direction vibration amplitude means <br/> constant by the vibration control means, a Coriolis force corresponding to the input angular velocity ω By detecting the amplitude in the Y-axis direction generated by Fc by the displacement detecting means and multiplying by the fixed constant , the angular velocity calculating means can output the input angular velocity ω. As described above, in the vibrating gyroscope according to the present invention, a piezoelectric element or the like is not attached to the vibrating means itself, and does not affect vibration . Change
In addition, since the amplitude in the X-axis direction is controlled to be constant,
Since the amplitude is proportional to the angular velocity, the amplitude in the Y-axis direction is fixed
By multiplying by a constant, extremely accurate angular velocity detection can be performed.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a vibrating gyroscope according to one embodiment of the present invention. FIG. 1A is a side sectional view, and FIG. 1B is a front sectional view.

The vibrating gyroscope 10 shown in FIG.
2, a vibrator 14 erected on the base 12 as vibrating means, a vibrating means 16 for vibrating the vibrator 14, and a displacement detecting means 18 comprising a photoelectric encoder. Further, a cylindrical housing 19 is installed on the base 12, and the housing 19 supports a displacement detecting means 18 at an upper end thereof.

The vibrator 14 is formed in a round bar shape, and the resonance frequencies in the X and Y directions are substantially the same. A cylinder 20 made of a prismatic ferromagnetic material is fitted on the upper part thereof, and a movable scale 22 is provided on the upper end of the vibrator 14. Further, the vibration means 16 includes a rod-shaped core 24 and an excitation coil 26 wound around the rod-shaped core 24,
It is fixed to the housing 19 via a bush 28. The tip of the rod-shaped core 24 is connected to the ferromagnetic cylinder 20.
It is close to the side part .

The vibrating gyroscope 10 according to the present embodiment is constructed as described above. Next, an angular velocity detecting mechanism will be described with reference to FIGS. First, as shown in FIG. 2, when the energized excitation coils 26 at a predetermined period (FIG. 3 (A)), a ferromagnetic cylinder 2 0 periodic manner attract by the magnetic force thereof (FIG. 3 (B)) . Then, the excitation cycle of the excitation coil 26 is adjusted to forcibly vibrate the vibrator 14 in the X-axis direction at substantially the resonance frequency f. Next, for example, a known angular velocity ωa is input, the output waveform of the excitation coil is compared with the waveform of the amplitude in the Y-axis direction generated by the Coriolis force, and the resonance frequency f and the output of the excitation coil are finely adjusted. The speed Vx is set to a constant value (FIG. 3C).

On the other hand, when an unknown angular velocity ω is input, a Coriolis force Fc corresponding to the angular velocity ω is generated in the Y-axis direction (FIG. 3D). As described above, since the resonance frequency f of the vibrator 14 is the same in the X-axis and Y-axis directions, the vibrator also vibrates in the Y-axis direction. As a result, by measuring the amplitude of the vibration in the Y-axis direction, the Coriolis force, that is, the angular velocity ω can be detected.

Next, the vibration control means used in the present invention 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 proportional to the velocity Vy on the Y axis (the maximum velocity point = the point where the Y axis amplitude becomes zero). Vy is Vx (X
Therefore, if Vx is controlled to be constant, the angular velocity ω is proportional only to the change in Vy.

Here, the distance X and the velocity V from the origin of the vibrator 14 are expressed by the following equations, respectively.

X = Px · sin ωt = Px · sin2πf · t V = dX / dt = 2πf · Px · cos2πf · t where Px: maximum amplitude, f: frequency, and t: time.
From the above equation 1, the maximum speed is cos2πf · t = 1 or −
At the time of 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 employed as the vibration control means 30 according to the present embodiment, and is constituted by a D / A converter 32, a calculator 34, a pulse width modulator 36, and an oscillator 38. I have. The X-direction amplitude detected by the X-axis encoder 18a is D / A
The data is converted into an analog signal by the converter 32 and compared with the target amplitude value 40 by the calculator 34. 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 measured amplitude value match. The oscillation frequency of the pulse width modulator 36 is
8 and is kept constant (resonant frequency).

On the other hand, the angular velocity calculating means is configured as shown in FIG. That is, the angular velocity calculating means 50 according to the present embodiment includes the counter 52 and the multiplier 54. Then, the Y-direction amplitude input from the Y-axis encoder 18b is digitized by the counter 52, and is further multiplied by a fixed constant A by the multiplier 54. Since the angular velocity ω is proportional to the amplitude in the Y direction, the multiplied 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,
For example, as shown in FIG. 7, even when a low-frequency disturbance is superimposed, it is hardly affected by the superposition.

Next, the displacement detecting means 18 of the present invention will be described with reference to FIGS. FIG. 8 is a longitudinal sectional view of the photoelectric encoder 18 constituting the displacement detecting means according to one embodiment of the present invention, and FIG.
A cross-sectional view along line IX is shown. In the figure, the photoelectric encoder 18 comprises a movable scale 22 and a fixed scale 60.
To detect the relative movement amount of both scales. On the upper surface of the fixed scale 60 in FIG. 8, one light emitting element 62 and eight light receiving elements 64a, 64b,... The lead wires of the light emitting element 62 and each light receiving element 64 are fixed to the printed board 66.

The movable scale 22 is provided with a first grating 68 shown in FIG. 10, and the first grating 68 is formed of a cross-shaped reflective grating including pentagonal reflective grating portions 70a, 70b,... 70d. . A lattice parallel to the Y axis is formed in the lattice parts 70a and 70b, and a lattice parallel to the X axis is formed in the lattice parts 70c and 70d. On the other hand, the fixed scale 60
Has a second grating 72 and third gratings 74a, 74b,..., 74h. And
The second grating 72 is a cross-shaped transmission grating including triangular transmission grating portions 76a, 76b,... 76d corresponding to the light emitting elements 62. The third gratings 74a, 74b,.
4h is a transmission grating corresponding to each of the light receiving elements 64a, 64b,... 64h.

Therefore, the light L emitted from the light emitting element 62
Are reflected by the first grating 68 via the second grating portions 76a, 76b,... 76d, and the reflected light is reflected by the third gratings 74a, 74b.
74h through the light receiving elements 64a, 64b,.
h. As described above, the photoelectric encoder according to the present embodiment has the second grating portions 76a and 76b, the first grating portions 70a and 70b, and the third grating portions 74a, 74b and 74c with respect to the relative movement in the X direction. , 74d, light receiving element 64
a, 64b, 64c, and 64d each function as a three-grid displacement detector. Further, with respect to the relative movement in the Y direction, the second lattice portions 76c and 76d, the first lattice portion 70c,
70d and the third grating portions 74e, 74f, 74g, 74h each function as a three-grid displacement detector.

That is, as shown in FIG. 12, the three-grating type displacement detector detects the amount of displacement based on a change in the overlap of three gratings (Journal of the optical society).
ofAmerica, 1965, vol. 55, No. 4, p373-381). The three-grating displacement detector shown in FIG.
The second and third gratings 74, the first grating 68 arranged in parallel between the two gratings 72, 74 so as to be relatively movable, the light emitting element 62 arranged on the left side of the second grating 72 in the drawing, A light receiving element 64 disposed on the right side of the three lattices 74 in the drawing.

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.
The illumination light limited by 8, 74 is photoelectrically converted and further amplified by a preamplifier 78 to obtain a detection signal s. Here, when the first grating 68 relatively moves in the x direction, for example, with respect to the second grating 72 and the third grating 74, of the illumination light from the light emitting element 62, the amount of light blocked by the gratings 72, 68, 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 relative movement amount of the first grating 68 is measured from the wavelength of the detection signal s and its division value. is there. Therefore, the first grating 68 is connected to the movable scale 2
Second, the second grating 72 and the third grating 74 are fixed scale 6
By setting them at 0, the relative movement amounts of both scales can be detected.

In this embodiment, the first grating 68
Grating portion 70a, 70b is the grating formation pitch P ₁ parallel to the Y-axis of the grating portion 70c, 70d is the grating pitch P ₁ 'parallel to the X-axis is formed. Also, the second lattice 72
Of the grating portion 76a, the 76 b Y parallel to the pitch P ₂ lattice shaft is formed, the grating portion 76c, the grating pitch P ₂ 'parallel to the X axis to 76d are formed.

Further, the third grating 74a has an Ax-phase grating, the third grating 74b has an Ax'-phase grating, and the third grating 7 has a third grating 74b.
Grating for Bx phase to 4c, grating for Bx 'phase in the third grating 74d is formed in parallel with a pitch P ₃ in the Y-axis, respectively, the third grating 74e grating for Ay phase, the third grating 74
are formed in parallel with a pitch P ₃ 'on the' lattice, grating for By phase Third grid 74 g, By the third grating 74h for phase 'X-axis respectively grating for phase Ay to f .

[0025] Therefore, when Ax = 0 °, with respect to Ax, Ax '= (different 1 / 2P ₃₎ 180 ° Bx = 90 ° (1 / 4P ₃ different) Bx' = different 270 ° (3 / 4P ₃ If Ay = O ゜, Ay ′ = 180 ° (different from ＰP ₃ ′) to Ay By = 90 ° (different from １ ／ P ₃ ′) By '= 270 ゜ (3 / 4P ₃ ′) (Different).

As a result, the light receiving elements 64a, 64b, 64
c, 64d, A
x-phase, Ax'-phase, Bx-phase, Bx'-phase signals can be obtained, Ax-phase output amplified by Ax-phase-Ax'-phase differential amplitude, and differential-amplitude from Bx-phase-Bx 'phase Amplified B
Obtain x-phase output. Then, the discrimination of the relative movement direction of the scale in the X direction is performed based on the shift direction of the phase of the Ax-phase output and the Bx-phase output, and the detection signal is electrically divided to detect the displacement with high resolution. ing.

On the other hand, the light receiving elements 64e, 64f, 64g,
Ay phase shifted by π / 2 from 64h,
Ay ′ phase, By phase, and By ′ phase signals can be obtained, and 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 according to the present embodiment, the moving direction and the moving distance in the X direction and the Y direction can be detected by one photoelectric encoder.

The respective gratings for detecting the X-axis direction and the respective gratings for detecting the Y-axis direction may have the same pitch as the corresponding gratings. However, the gratings may be different if a different precision is required for each direction. It is also preferable to set the pitch.

As described above, according to the vibrating gyroscope according to the present embodiment, the vibrator 14 can have a very simple structure, and the attachment of a piezoelectric element or the like is not required, so that the error can be reduced. it can. Also, since the amplitude and frequency of vibration in the X-axis direction are controlled using a non-contact photoelectric encoder with the vibrator, and the amplitude in the Y-axis direction is detected using the same encoder, the angular velocity ω is obtained. , The angular velocity ω can be measured with high resolution and high accuracy.

In the above embodiment, the housing 1
It is preferable that the linear expansion coefficient of the vibrator 14 be substantially equal to that of the vibrator 14. That is, if the linear expansion coefficients of the housing 19 and the vibrator 14 are significantly different, the movable scale 2
This is because the gap between the fixed scale 2 and the fixed scale 60 changes, which may increase the measurement error.

It is preferable that the inside of the housing 19 has a sealed structure. That is, a change in the air pressure inside the housing 19 may affect the vibration of the vibrator 14.

In the above embodiment, the excitation coil 2
6 was pulsed, for example, as shown in FIG.
As shown in (A), a sinusoidal voltage may be applied. At this time, the sawtooth voltage is synchronized with the sinusoidal voltage,
The phase is confirmed at t0 and t2, and the amplitude in the Y-axis direction is read at t1 and t3. Although using a cylindrical resonator in the embodiment, for example, FIG. 14 (A) to indicate to a cylindrical shape, the
It is also possible to adopt a square cross-sectional shape shown in FIG. (B), a square tubular shape shown in FIG.

The vibrator has a moment of inertia about the X-axis and Y
The moment of inertia about the axis is substantially the same, and the resonance frequency f
Are required to be substantially equal. Further, it is preferable that the shape of the vibrator be a stepped shape as shown in FIG. 15A or a tapered shape as shown in FIG. The vibrator is required to have substantially the same moment of inertia around the X axis and moment of inertia around the Y axis, and to have substantially the same resonance frequency f.

In the above-described embodiment, the ferromagnetic cylinder is used for the vibrator portion facing the vibrating core 24. However, it is preferable to use a magnet or the like, for example.

[0035]

As described above, according to the vibrating gyroscope according to the present invention, the vibrator is vibrated in a non-contact manner, and its displacement is detected in a non-contact manner. In addition, highly sensitive angular velocity detection can be performed . Further, since the X-axis direction amplitude is controlled to be constant,
Since the axial amplitude is proportional to the angular velocity, the Y-axis amplitude
Is multiplied by a fixed constant, extremely accurate angular velocity detection can be performed.

[Brief description of the drawings]

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

FIG.

FIG. 3 is an explanatory diagram of the principle of measuring the angular velocity of the vibrating gyroscope shown in FIG.

FIG.

5 is an explanatory diagram of a vibration control unit of the vibration gyro shown in FIG.

FIG. 6 is an explanatory diagram of an angular velocity calculating means of the vibrating gyroscope shown in FIG.

FIG. 7 is an explanatory diagram of the influence of low-frequency disturbance on the vibration gyro shown in FIG. 1;

FIG.

FIG.

FIG.

FIG.

FIG. 12 is an explanatory diagram of a displacement detecting means of the vibrating gyroscope shown in FIG. 1;

FIG. 13 is an explanatory diagram of an example of a voltage waveform applied to an excitation coil.

FIG.

FIG. 15 is an explanatory diagram of an example of a vibrator.

[Explanation of symbols]

 12 Base 14 Vibrator 16 Vibration means 18 Displacement detection means 30 Vibration control means 50 Angular velocity calculation means

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Shingo Kuroki 165, Sakado, Takatsu-ku, Kawasaki-shi, Kanagawa Pref. Mitutoyo Development Laboratories (56) References JP-A-154915 (JP, A) JP-A-63-121709 (JP, A) JP-A-62-95421 (JP, A) JP-A-61-100608 (JP, A)

Claims (1)

(57) [Claims] A vibrating means erected on a base; a vibrating means disposed in close proximity to the vibrating means for applying a vibrating means in the X-axis direction to the vibrating means by a magnetic force; a movable scale was has a movable scale and oppositely disposed fixed scale, and displacement detection means for detecting the amplitude of the respective X-axis direction and the Y-axis direction of the vibrating means, from said displacement detecting hand stage When the detected X-axis direction amplitude is constant
Said vibration control means for vibration control of the vibration means so that a fixed constant in the Y-axis direction amplitude inputted from the displacement detecting hand stage
Vibrating gyro comprising: the angular velocity calculating means for calculating the angular velocity multiplied by the number, the