JP2520894B2 - Direction detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a method for detecting the direction of a ship, an aircraft, etc. using a gyro, more specifically, rotating a rade gyro to affect the influence of the earth's rotation. Relates to a method for detecting an azimuth from a change in gyro output.

<Prior Art> The principle of the raid gyro is that, as shown in FIG. 7, the angular velocity detection shaft (20) of the gimbal (10) is supported on a moving body (not shown), and the spin axis of the gyro rotor (30) ( 40) is orthogonal to the angular velocity detection axis (20) and the gimbal (1
0), the spin axis (40) is kept horizontal, and the gyro rotor (30) is rotated counterclockwise at high speed to impart inertia to the spin axis (40) so that it remains horizontal. can do. Then, when the moving body rotates in the clockwise direction at the angular velocity ω, precession occurs and the gyro rotor (30) tilts in the vertical plane. That is, the angular velocity detection shaft (20) rotates. Then, the rotational torque of the angular velocity detection axis (20) and the spring (50) accompanying the precession
And the reaction force with the damper (60) and the like are balanced to detect a displacement angle θ proportional to the angular velocity ω.

Further, the integral rate gyro is to replace the spring (50) of the rate gyro with an electric torque to detect a relatively small input angular velocity.

That is, the azimuth of the moving body during rotation can be detected by adding the result of integrating the angular velocity detected by the gyro to the initial azimuth detected by the gyro compass or the like.

<Problems to be Solved by the Invention> However, in the above-described azimuth detection method, the spin axis (40) drifts in the vertical plane due to the viscous resistance of the damper (60) and the like, which causes an error. Gyro drift δ
The azimuth detection error Δθ due to Ω is expressed by the following equation.

_{^{Δθ = ▲ T O ▼ δΩ ·}} t dt = δΩT 2/2 ... (1) where, T is the elapsed time since the initial azimuth setting.

That is, as shown in the above equation (1), the azimuth detection error increases as the measurement time T increases.

For example, assuming that the gyro drift could be suppressed to 0.3 deg / hr, the bearing detection error after 10 days (1)
As calculated by the formula, T = 10 × 24 = 240hr , from δΩ = 0.3deg / hr ^2, the ^{Δθ = 0.3 × 240 2/2} = 8640deg and very large errors.

Conversely, calculating the gyro drift required to reduce the direction detection error to 1 deg or less in 10 days yields δΩ <2 / T ² = 2/240 ² = 3.4 × 10 ^-5 deg / hr ² , which is not realizable. Possible accuracy is required.

For this reason, when performing azimuth detection for a long time using a gyro, it is necessary to make some corrections (for example, use a gyro compass to detect the azimuth and set the initial azimuth). There is a problem.

<Object of the Invention> The present invention has been made in view of the above problems.
An object of the present invention is to accurately detect the azimuth regardless of the error due to the gyro drift when the azimuth is detected.

<Means for Solving Problems> In order to achieve the above object, the azimuth detecting method of the present invention rotates a rate gyro, generates a reference signal in synchronization with the rotation, and outputs the reference signal and an output signal from the gyro. Is detected, and the azimuth of the moving body is detected based on the phase difference.

<Operation> According to the azimuth detecting method of the present invention as described above, by rotating the rate gyro at one point on the earth, the direction of the gyro axis with respect to the direction of the horizontal component force of the rotation angular velocity of the earth is changed. Since it can be influenced by the rotation of the earth, the output of the gyro can be changed in a sine wave shape. When the moving body rotates and moves in the local horizontal plane, an error occurs due to the rotation component of the moving body being superimposed on the output of the gyro. In this case, the azimuth of the moving body is detected by using the signal corresponding to the rotation angle of the gyro as the reference azimuth and detecting the phase difference between the output signal from the gyro and the reference signal when the moving body rotates. That is, the azimuth of the moving body can be detected by the rotation angle corresponding to the average value or the peak value of the maximum value and the minimum value of the output of the jig and the rotation angle corresponding to the phase difference.

<Embodiment> An embodiment will be described below with reference to the accompanying drawings.

FIG. 1 is a perspective view showing an embodiment of a direction detecting method using a gyro, and a moving body (1) such as a ship or an aircraft.
Inside, there is a substantially disk-shaped rotary table (3) that is associated with a drive source (2) such as a servo motor, a pulse motor, a synchro motor, etc., and can be rotated parallel to a horizontal plane. There is an existing gyro (4).

Fig. 2 shows the gyro (4) mounted on the moving body (1) at the latitude θ, where the rotation angular velocity of the earth is Ω, and the rotation angular velocity of the earth at the latitude θ is shown. The horizontal component force of Ω is Ω cos θ. When the rotary table (3) is rotated under this condition, when the angular velocity detection axis (43) faces north or south, it is most affected by the angular velocity Ω due to the rotation of the earth, and the angular velocity detection axis (43) When orthogonal to the axis of rotation of the earth, that is, when facing east or west, it is hardly affected by the rotation of the earth.

That is, by rotating the rotary table (3), the direction in which the gyro (4) is oriented with respect to the axis of rotation of the earth is changed so that the angular velocity Ω of the earth is affected.

Therefore, the output of the gyro (4) when the rotary table (3) is rotated changes sinusoidally with a peak value that is proportional to Ωsosθ (see FIG. 2B).

The gyro (4) will be described in more detail. The gyro (4) is a conventionally known one. The spin shaft (4) of the gyro rotor (41) will be described in detail with reference to FIG.
Gimbal (4) so that 2) is orthogonal to the angular velocity detection axis (43).
The gimbal (44) is mounted on the case (45) so that the angle detection shaft (43) rotates about the center line. The angular velocity detection shaft (43) is made of a magnetic material.
A pole dumbbell-shaped rotor (46) is attached to the rotor (46)
A four-pole stator (47) for extracting the output from is attached to the case (45). That is, 1 of the stator (47)
One phase of the power for rotating the gyro rotor (41) is normally supplied to the next coil (48), and the pole of the rotor (46) approaches the pole (47a) of the stator (47). Then, the voltage induced in the secondary coil (49a) wound around the pole (47a) increases, and the voltage induced in the secondary coil (49b) wound around the pole (47a) decreases. Become.
The phases of the outputs induced in the secondary coils (49a) and (49b) are different from each other by 180 degrees.

Therefore, from the output terminal of the secondary coil (49) in which the secondary coils (49a) and (49b) are connected in series, a voltage signal obtained by adding both induced voltages is output, and the angle can be known from the peak value. The direction of the angular velocity detection axis (43) can be known by which half cycle the value appears (see FIG. 3B).

Now, when the spin shaft (42) is rotated counterclockwise at a high speed, the spin shaft (42) maintains the horizontal direction due to the inertia of rotation. In this state, if the rotary table (3) is rotated clockwise, the gyro rotor (41) performs a precession movement by the rotary input of the rotary table (3). That is, the angular rotation detecting shaft (43) is rotated by an angle proportional to the input angular velocity, and with this rotation, the gimbal (44) and the rotor (46) attached to the angular velocity detecting shaft (43) are rotated, and the stator (47) is rotated. The electric potentials induced in the pole (47a) and the pole (47b) of () become unbalanced, and the electric potential proportional to the angular velocity of the rotary table (3) is output.

Then, above the output potential proportional to the angular velocity of the rotary table (3) above, the angular velocity Ω of the earth at the point of latitude θ
The sinusoidal output signal affected by the component force Ω cos θ of is superimposed.

A sinusoidal signal component due to the influence of the earth's angular velocity Ω is extracted from the superimposed signal, and the angular velocity detection axis (43) when the output signal becomes maximum or minimum during one rotation of the rotary table (3) ) Can be detected in the north or south direction by reading the direction.

Therefore, the traveling direction of the moving body (1) can be detected from the rotation angle of the gyro (4) corresponding to the maximum value or the minimum value.

According to the above-described azimuth detecting method, a voltage signal proportional to the angular velocity of the rotary table (3) is output, and a sinusoidal signal due to the influence of the rotation of the earth is superimposed on this voltage signal.
Since the azimuth is detected from the sinusoidal waveform, even if there is a drft, the output level only changes and there is no azimuth detection error due to drift. Further, since it is possible to extract the waveform of the output signal for each rotation and measure the azimuth, it is not necessary to stabilize the scale factor (input angular velocity and output ratio) for a long time.

Furthermore, the azimuth measurement accuracy of the above embodiment will be examined. For example, when the azimuth is detected with an accuracy of 1 degree, the measurement accuracy of the gyro (4) itself may be Ω cos θ × sin 1 °. If we explain more concretely in the vicinity of Japan (latitude 30 degrees), the Earth's rotation angular velocity Ω is 15.12 ° / hour, which is 15.12 × cos (π / 6) = 0.23 ° / hour per hour. It only needs to have measurement accuracy and can be measured with an existing gyro.

Higher sensitivity can be obtained when the output change rate with respect to the angle change is the largest as the reference of the azimuth detection, that is, when the output crosses 0. In order to determine the reference at which the output crosses 0, the average value of the maximum value and the minimum value in each cycle of the output waveform is used as the reference, and the direction indicated by the angular velocity detection axis (43) at that time is read as west or east. If the average value is obtained by measuring a plurality of times, the measurement accuracy can be further increased.

According to the above-described azimuth detection method, when the rotational angular velocity of the moving body (1) is small as in a ship, the angular velocity of the turntable (3) is sufficiently higher than the rotational angular velocity of the moving body (1). By setting (specifically, the rotation cycle of the table (3) is approximately 1 Hz), the error due to the influence of the rotation of the moving body (1) can be almost ignored.

By rotating the gyro (4) at least once, one of the north, south, east, and west directions is detected, and the angular velocity associated with the rotation of the moving body (1) is integrated based on the detected direction. It is also possible to detect the azimuth of the moving body (1). Then, when an error occurs in the direction detection result for a long time due to the influence of drift, the gyro (4)
Rotate, detect the north or south direction from the maximum or minimum value of the output, and add the rotation angle of the corresponding gyro (4) to accurately move regardless of the drift of the gyro (4). The orientation of the body (1) can be detected.

Next, the azimuth detecting method of the present invention in the case where the moving body (1) moves at high speed in a local horizontal plane with zigzag movement and the like will be described.

In this case, the rotation component of the moving body (1) itself is superimposed on the output of the gyro (4). That is, since the angular velocity due to the rotation of the moving body (1) is superimposed, the error due to the influence of the rotation of the moving body (1) cannot be ignored.

Therefore, as shown in FIG. 4, when the traveling direction of the moving body (1) rotates from north to east to south to west, the output of the gyro (4) sequentially shifts in phase, The reference signal is generated in synchronization with the rotation of (3) and the reference direction is set, and the reference signal and the gyro (4)
The azimuth is detected by detecting the phase difference from the output signal of and then adding or subtracting it to the reference azimuth.

Specific examples of the reference azimuth include the nose or bow direction of the moving body (1).

The phase difference detection will be described in detail with reference to the block diagram of FIG. 5 and the waveform diagram of FIG. 6. The table (3) is periodically rotated by the drive source (2), A reference signal (see FIG. 6A) synchronized with the rotation of the table (3) is generated by the synchronization signal generation unit (5) and supplied to the synchronization detection unit (6). Then, the synchronous detection unit (6) synchronously detects the output signal from the gyro (4) based on the reference signal, and supplies the synchronously detected signal to the phase shift unit (7). Then, the phase shift section (7) shifts the reference signal so that the output signal of the synchronous detection section (6) becomes maximum, whereby the reference azimuth and the phase angle φ of the output signal from the gyro can be detected. (See Figure 6B).

FIG. 6B shows an example in which the phase difference between the maximum value of the output of the gyro is detected. The phase difference between the north or south direction and the reference direction is detected. Also 0
It is also possible to detect the phase difference at points of 180 degrees, 270 degrees, and 180 degrees.

According to the above-described azimuth detecting method for detecting the phase angle φ, the DC component of the output signal of the gyro (4) is not taken in as a signal, and therefore the fluctuation of the DC component due to the drift is not related to the detection accuracy of the phase angle φ. .

In summary, in the moving body (1) having a slow rotation speed, the table (3) is rotated, and the angular velocity detection axis (43) when the output signal of the gyro (4) has the maximum value or the minimum value in one cycle. ) Is the north or south, or the direction of the angle detection axis when pointing the average of the maximum and minimum values is east or west, and the azimuth is detected. Correctly, in the moving body (1) having a high rotation speed, the azimuth can be detected by detecting the phase in which the output signal of the gyro (4) shifts with the rotational movement of the moving body (1).

<Effects of the Invention> As described above, according to the method for detecting a direction of a moving body of the present invention, when the moving body is rotationally moved in the local horizontal plane, the reference signal corresponding to the rotation angle of the gyro and the gyro are used. It is said that the azimuth of the moving object can be detected by the rotation angle corresponding to the average value or the peak value of the maximum value and the minimum value of the gyro output and the rotation angle corresponding to the phase difference from the phase difference with the output signal of Has a unique effect.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a direction detecting method using a gyro, FIG. 2 is a view for explaining a state under the influence of the rotation of the earth, and an output waveform diagram at that time, FIG. Is an enlarged view of a part of the rate gyro cut out,
And FIG. 4 is a diagram illustrating output extraction, FIG. 4 is a diagram illustrating an output state when a moving body rotates, FIG. 5 is a block diagram illustrating an embodiment of the present invention, and FIG. 6 is a phase difference. FIG. 7 is a waveform diagram showing the detection of the above, and FIG. 7 is a diagram showing the principle of the rate gyro. (1) ... moving body, (3) ... turning table, (4) ...
…gyro. (5) ... Synchronization signal generation section, (6) ... Synchronization detection section, (7) ... Phase shift section.

Claims (1)

(57) [Claims] 1. A rate gyro is rotated, a reference signal synchronized with the rotation is generated, a phase difference between the reference signal and an output signal from the gyro is detected, and the azimuth of a moving body is detected based on the phase difference. Orientation detection method characterized by.