JPS63285411A - Gyroscopic apparatus - Google Patents

Abstract

PURPOSE:To obtain a highly accurate gyroscope with limited variations in drift, by detecting the direction of vibration of a cylindrical vibrator with a displacement detector. CONSTITUTION:When a case 11 turns by a certain angle in the direction of the arrow on the Z-Z axis of a cylindrical vibrator 13, declination takes place by a value proportional to an angle at which the case 11 turns between the case 11 and the vibrator 13 in a coordinate system fixed on the case 11, as the vibration mode of the cylindrical vibrator 13 is constant with respect to an inertial space according to the Foucault's theory. Then, when a computing section 16 stores the above-mentioned declination to control the reference vibration direction of the vibration mode to the position of the declination, the reference vibration direction of the vibration mode is proportional to an angle of rotation of the case 11. Thus, an angle of rotation inputted into a gyroscope can be detected relying on the reference vibration direction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a gyro device, particularly a vibration type gyro device.

[Conventional technology]

Although the present invention is different in principle from various types of gyros conventionally used, a vibrating gyro whose principle and structure are relatively similar to the present invention will be explained using FIG. 5 as a conventional example. . In the example shown in the figure, the tuning fork (1) is
It is attached to the base (2) via the flexible shaft (3). Tuning fork (1
), a displacement detector (6) and a drive coil (4) are installed near the upper end of the tuning fork (1), and the output of the displacement detector (6) is input to the drive coil (4) through a drive amplifier (5).
) is kept constant.

Around the axis CZ-Z) of the deflection axis (3) of the tuning fork (1),
When the angular velocity Ω is input, the tuning fork (vibration velocity V1 of 11,
A Coriolis force Fc velocity corresponding to the input angular velocity Ω is generated, and as a result, the entire tuning fork (11) alternately rotates around the axis (Z-2). That is, torsional vibration is generated in the tuning fork (1). do.

In the conventional example shown in this FIG. The gyro device is constructed by detecting the input angular velocity Ω through synchronous rectification.

[Problem that the invention seeks to solve]

However, in such conventional vibrating gyro devices, the Coriolis force generated by input angular velocity acting on a vibrating body such as a tuning fork (1) is converted into an angular displacement, and this displacement is detected by a torsion detector (8). Due to the detection method, detection sensitivity is low. Furthermore, when a piezoelectric element or the like is used as the torsion detector (8),
Temperature has a large effect on detection sensitivity. Also, a tuning fork (
1) Unbalance of the tuning fork (
This method has many disadvantages, such as requiring precise balancing of 11 components and requiring a lot of time for balance adjustment.

Therefore, the present invention aims to provide a new gyro device that eliminates the drawbacks of the conventional gyro device described above.

[Means for solving problems]

The gyro device according to the present invention supports a cylindrical vibrating body (13) by struts (12a) and (12b) fixed to an outer casing (11). Drive elements (14a) to (14d) for driving the vibrating body are arranged on this vibrating body, and driving circuits (30), (31) are connected to the vibrating body via these elements.
The vibrating body is driven in the radial direction by (Z-
Z) Detection elements (15a) to (15h) for detecting the radial displacement of the end in the axial direction are installed in the outer casing, and their outputs are supplied to the calculation section.

[Effect]

In the above-described gyro device of the present invention, the outer casing (11)
(Z-Z) of the cylindrical vibrating body (13) at a certain angle
When rotated in the axial direction, the vibration mode of this cylindrical vibrating body is constant with respect to inertial space due to Foucault's principle, so in a coordinate system fixed to the outer housing, the vibration mode between the outer housing and the vibrating body is , the angle is deflected by an amount proportional to the angle by which the outer casing is rotated.

If this deflection angle is memorized and the reference vibration direction of the vibration mode is controlled to be at this deflection angle position, the reference vibration direction of the vibration mode will be proportional to the rotation angle of the outer casing.

Therefore, the rotation angle input to the gyro can be determined from this reference vibration direction.

〔Example〕

An example of the gyro device of the present invention will be described below with reference to FIGS. 1 to 4.

FIG. 1 shows a vibrating part (
A perspective view showing the inside of the vibrating part (lO
) mainly consists of an outer casing (11) and a vibrating body (13) arranged inside the outer casing (11).

The outer casing (11) is a cylindrical container whose openings at both ends are sealed so that the inside is almost vacuum. They are arranged so that their longitudinal axes, in other words, their central axes (Z-Z), coincide with each other. Perpendicular to the (Z-Z) axis, the outer casing (11)
and a pair of supports (12a), (12a), whose longitudinal directions are along one common diameter of the vibrating body (13), and approximately at the center of the vibrating body (13) in the (Z-Z) axis direction. 12
b) is placed between the two as follows. That is, the outer ends of both supports (12a) and (12b) are fixed to the inner peripheral surface of the cylindrical outer casing (11), and the inner ends are fixed to the cylindrical vibrating body (12b).
13).

Therefore, the vibrating body (13) is supported by both supports (12a) and (12b) in the cylindrical outer casing (11) so that it can freely vibrate (deform) as described below. .

The cylindrical vibrating body (13) is made of, for example, a metal such as a constant elastic material, and the wall thickness of the cylindrical portion is substantially uniform. Further, on the outer peripheral surface of the central part of the vibrating body (13), for example, four piezoelectric elements (14a) to (14d) for driving the vibrating body (13) are adhered at equal intervals on the same circumference. has been done. Furthermore, a plurality of pieces, eight pieces in the third example, are placed on one end of the cylindrical vibrating body (13) in the (Z-Z) axis direction, which are opposed to each other with a gap on the outer peripheral surface of the upper end in the example of FIG. The capacitive displacement detectors (15a) to (15h) are connected to the outer casing (11).
) are provided at equal intervals on the inner circumferential surface of the vibrating body (13) to detect the displacement of the vibrating body (13).

In addition, the four piezoelectric elements (14a) to (14d)
) and eight displacement detectors (15a) to (15h) are each connected to a calculation unit (16), thereby driving the vibrating body (13) and detecting the deflection angle.

Regarding the drive of the vibrating body (13) and its displacement detection, the second
This will be explained using the drawings and FIG. In addition, FIG. 2 shows the center part of the vibrating body (13) in the longitudinal direction (Z-Z)
-Z) is a sectional view perpendicular to the axis, and FIG.
) is a side view.

The piezoelectric elements (14a) to (14d) are connected to the vibrating body (1
3) At the outer periphery on the same circumference in the center of the (Z-Z) axis,
As shown in FIG. 2, four piezoelectric elements are bonded at equal intervals so that the directions of polarization axes of adjacent piezoelectric elements are different from each other.

These piezoelectric elements (14a), (14e) and (14b).

(14d) are the drive circuits (30 and 30), respectively, as shown in FIG.
) and (31). These piezoelectric elements (
When piezoelectric elements (14a) to (14d) are driven with the same voltage, the piezoelectric elements (14a) to (14d) have the same polarity (14a) and (14d).
In 14e), (146), and (14d), the direction of strain is the same, but the direction of strain is different between polarities, and the deformation becomes a chain-like deformation mode as shown in FIG. The shape of the end face of the vibrating body (13) when viewed from the (Z-Z) axis direction is an ellipse as shown in FIG. In the case of this vibration mode, the center of the (Z-Z) axis of the vibrating body (13) becomes a vibration node, so if this point is supported, the vibration will not be transmitted to the outside, and the support Therefore, the vibration mode does not change. Therefore, as mentioned above, at this point, the vibrating body (13
) is desirable.

Now, when the drive voltage to the piezoelectric elements (14a) to (14d) is changed in an alternating current manner, the vibration mode of the vibrating body (13) changes between the solid line and the broken line shown in FIGS. 2 and 3. It becomes vibration mode.

When driving the vibrating body (13), the vibration of the vibrating body (13) is affected by internal damping of the vibration of the vibrating body (13) due to external disturbances such as temperature changes, and by the influence of gas molecules in the outer casing (11).
In order to prevent this, eight capacitive displacement detectors (15a) to (15h) fixed to the outer casing (11) are used to measure the imaging displacement of the vibrating body (13). ) and their outputs are detected by displacement detectors (15a) to (1
5h) and the same number of displacement detection circuits (17a) to (17h), and the output of each displacement detection circuit (17a) to (17h) is switched by a common switch c'i9) and A/D converted. A/D conversion is performed in the unit (20), and the computer (1
6'). Note that the power source (18) is a high frequency power source for driving each displacement detector (15a) to (15h).

The displacement at the position of each displacement detector (15a) to (15h) inputted to the computer (16') via the A/D converter (20) (from g, to the peak phase difference calculation unit (21),
The phase of the peak position of the vibration mode of the vibrating body (13) with respect to the reference coordinates is calculated, and the peak amplitude value is calculated from the output in the beak 1 width calculating section (22). This peak amplitude value is compared with a reference amplitude intermediate value from a reference amplitude source (26) by a comparator (26').

On the other hand, the phase difference from the peak phase difference calculation unit (21) is supplied to the reference angle calculation unit (23), which determines the required peak vibration direction, and sets the peak position in this direction. ) and the output ° of the comparator (26') are processed in the coordinate decomposition calculation section (27), and the output is sent to the mouth/A converter (2
B) It is converted into an analog voltage by (29), and the re-output is supplied to drive circuits (30) and (31), and the piezoelectric elements (14a) to (14d) are driven by the outputs of both.

The drive system constitutes a self-excited vibration system, and the drive frequency of the vibrating body (work 3) matches its primary natural frequency, and its peak amplitude is kept constant.

The drive system of the vibrating body (13) is configured as described above, but when using the above configuration as a gyro,
The arithmetic unit (16) is controlled as follows.

When the power source (not shown) of the device including the power source (18) is turned on, the peak position of the vibration mode of the vibrating body (13) changes from the reference direction of the reference coordinates (fixed coordinates of the outer casing (11)) (for example, the The direction must be the X direction in Figure 2.This calculation is
Do it as follows. That is, the vibrating body (13
) is the outer radius of displacement detectors (15a) to (1
The displacement of the vibrating body (13) during vibration detected by 5h) is the difference between the equation of an ellipse centered at the origin 0 of the reference coordinates and the circle with radius rs, so (1-a) x2-2hxy (1-b) y2-(1
+R2) =O... It is expressed by the equation (1). Here, a, b, h, and R are constants.

As mentioned above, the displacement detectors (15a) to (15h) have four
There are 8 displacement detection circuits (17a
) to (17h') switch output! (19) and detects the displacement of eight points of the vibrating body (13).

In order to increase the detection accuracy, among these displacements, (Z-
Z) Displacement detectors (15a) and (15) facing each other across the axis
e ) , = The average value of the displacements of (15d) and (15h) is determined and converted into displacement in four directions. Then, the curve equation of equation (1) is determined from the displacements in these four directions. That is, (calculate the constants a, b, h, and R of equation 11.

Then, the rotation angle θ of the elliptical vibration mode can be found as follows. This calculation is executed in the peak phase difference calculation section (21).

At startup, the reference angle in the reference angle calculation unit (23) is set to the reference orientation (for example, the X-axis). From the above calculation results, if the peak position of the ellipse does not match the reference orientation, the coordinate decomposition calculation unit (27) uses the same principle as a resolver to calculate the voltage values to be applied to the piezoelectric elements in the X and Y directions. Decomposed by rotation angle θ, drive circuit <30).

(31) to piezoelectric elements (14a) to (14d
), the peak position of the ellipse will match the reference orientation. In addition, the peak amplitude calculation unit (22) is a part that calculates the peak displacement of the vibration mode from the constant obtained by the peak phase difference calculation unit (21), and this loop controlled by

The reference orientation is fixed to, for example, the X-axis, and after the gyro alignment is completed, the angle and angular velocity measurement mode is entered. This measurement mode is different from the alignment described above in that the value of the reference angle calculation section (23) is set to the latest value. In this mode, an angular velocity Ω is input in the direction of the gyro's input axis, that is, the (2-Z) axis, and the outer casing (
11) rotates, according to Foucault's principle, the reference orientation of the elliptical vibration mode has a certain delay angle determined by the moment of inertia around the three axes of the vibrating body (13), but the rotation from the reference orientation of the vibration mode The angle is approximately proportional to the input rotation angle. however,
In order to maintain this proportional relationship over a long period of time, a feedback system as described below must be introduced in order to cancel out the disturbance torque of the vibrating body (13). That is, at a certain moment, angular velocity acts on the coordinate system (X-Y coordinate system in Figure 4) fixed to the reference direction of the vibration mode, and the coordinate system rotates by θ according to the above principle, and the X-Y coordinate system in Figure 4 Assume that the reference orientation is rotated to the '-Y' coordinate system. The displacement of the vibrating body (13) is detected by sampling in a time sufficiently shorter than the vibration period of the vibrating body (13) according to a command from the computer (16'), and the displacement detectors (15a) to (15h)
) The outputs of the displacement detection circuits (17a) to (17h) are switched by the switch (19) and measured, and the rotation angle at this time is calculated in the same way as in the alignment described above. This calculated value is set as a new value in the reference angle calculation section (23). That is, when the input angular velocity Ω enters the gyro and the reference orientation rotates with respect to the outer casing (11), the reference orientation position after rotation is fixed to the X'-Y' coordinate system of FIG. 4.

When further input is added, from the X'-Y' coordinate system to
“The reference orientation changes to the coordinate system (not shown), but the operation of the calculation unit (16) at this time is from the x-y coordinate system to
'It is the same as converting to a coordinate system.

In other words, the set value of the reference angle calculation section (23) is set to the rotation angle as an integral value from the start of the measurement mode. Therefore, by reading the contents of the register of the reference angle calculating section (23) and multiplying this by the above-mentioned proportionality constant in the angle calculating section (25), it is possible to measure the angle input to the gyro. In addition, by time-differentiating the angle obtained from this in the angular velocity calculation section (24),
The input angular velocity Ω can also be measured at the same time. Thus, according to the present invention, the angle and angular velocity can be measured.

Note that the wall thickness of the cylindrical portion of the cylindrical vibrating body (13) in the (Z-2) axis direction does not need to be uniform;
Z) If the thickness of the cross section perpendicular to the axis is the same, the structure may be made thicker at the center than at both ends, for example.

In addition, in the example where the children are connected, 1 to 1 set of piezoelectric elements (14a)
14d) was provided at the center of the cylindrical vibrating body (13) in the (Z-Z) axis direction, in other words, at the node of the vibrating body (13) during vibration, but two sets of similar piezoelectric elements (14a) - (14
d) at both ends of the vibrating body (13) in the (Z-Z) axis direction,
(Z-Z) It is fixed along the axial direction so that the polarity is reversed, and 2
A drive circuit (
30) and (31) in the same manner, and the photographing object (13
) can be vibrated so that their vibration modes have a phase difference of 180° from each other, similar results can be obtained.

〔Effect of the invention〕

Since it has a structure in which the vibration direction of a cylindrical vibrating body is detected by a displacement detector, it is basically a rate integrating gyro (not a rate gyro), and a highly accurate gyro with little drift fluctuation can be obtained.

Due to its simple structure, a low-cost, high-performance gyro (
) can be done.

Unlike mechanical gyros, there are no sliding parts such as ball bearings, so it is highly reliable and has a long life.

Since elements with high temperature sensitivity such as piezoelectric elements are not used in the detection system, it is possible to obtain a gyro with essentially excellent temperature characteristics.

By processing the output of the displacement detector, an angular velocity signal can also be output.

[Brief explanation of the drawing]

FIG. 1 is a route map of an embodiment of the present invention, FIG. 2 is a diagram showing the vibration mode at the central position in the longitudinal axis direction of the vibrating body, FIG. 3 is a diagram showing the overall vibration mode of the photographing body, and FIG. The figure is an explanatory diagram of coordinate rotation of a reference angle, and FIG. 5 is a perspective view of a conventional vibrating gyroscope. In the figure, (11) is the outer casing, (12a), (1
2b) is the support body, (13) is the vibrating body, (14a)
- (14b) are piezoelectric elements, (15a) - (15h) are displacement detectors, (16) is an arithmetic unit, and (16') is a calculator, respectively.

Claims (1)

[Scope of Claims] 1. An outer casing with both open ends sealed, a cylindrical vibrating body disposed within the outer casing, and a support body having both ends fixed to the vibrating body and the outer casing, respectively. a drive element and a drive circuit that drive the vibrating body in the radial direction; a displacement detector that detects the radial displacement of the vibrating body with respect to the outer casing; and an output signal from the displacement detector as input; A gyro device comprising: a calculation section that calculates a phase difference and amplitude of a vibration mode of a vibrating body with respect to a reference position, and adds the calculation results to the reference position to obtain an input angle or angular velocity. 2. The gyro device according to claim 1 is characterized in that the cylindrical vibrating body is supported by its vibration nodes.