JPH01269009A - True north measuring method - Google Patents

Abstract

PURPOSE:To find the deviation between a reference position and the true north direction so as to reduce the measuring time and to improve the measuring accuracy by making the light of a light source incident on a light receiver array after the light is reflected by a mirror. CONSTITUTION:The light image formed on a light receiver array 7 moves on the array 7 in accordance with the precession of a gyroscope 2. Each light receiver of the array 7 is connected to a position and time detector 12 through preamplifiers 10. Signals from a clock 11 are also inputted to the detector 12 and the time of each light receiver is measured from the commencement of the measurement so that when light is made incident to which light receiver of the array 7 can be detected. Since the intervals between each light receiver on the arraty 7 is known, the change in position of the light image against a reference position on the array 7 in the lapse of time can be measured.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of measuring due north using a gyro.

(Prior Art) A conventional method for measuring the true north direction using a gyro is shown in FIG. 3. That is, a gyro 32 with a mirror 31 attached thereto is suspended from a frame 33 by a thin hanging wire 34. An index 36 such as a slit illuminated by the light M35 is reflected by the mirror 31 on the gyro and is imaged on the focus plate 39 by the objective lens 38, and the position of the image is observed by the eyepiece 37. be done.

The measuring device is set so that the optical image 42 of the index 36 is approximately on the reference point 0 of the scale 41 on the focus plate 39, and the reference point 0 is set as a temporary north direction. Gyro 3 by preset
When finger #A 2 vibrates, the optical image of finger #A 36 is observed to swing left and right on a scale 41 arranged horizontally in the field of view of the eyepiece, as shown in FIG.

Methods for measuring true north using a device set up in this manner include the period measurement method and the oscillation measurement method.

In the period measurement method, as shown in FIG. 4, an optical image 42 of an index wavering on a scale 41 of an eyepiece 37 is followed by the eye due to a preset. As shown in FIG. 5, the time t1 when the optical image 42 of the index crosses the reference point 0 of the scale 41,
Measure t2... with a stopwatch, and check the time t
Assuming that the midpoint of 2... is where the amplitude of the preset is at its maximum, find the average value (m, + mx)/2 of the maximum value m and the minimum value m2 of the scale at that time, and set the reference point 0. Find the amount of deviation Δα. The true north direction is determined as the direction in which a deviation amount of Δα is added to the temporary north direction (reference point O of the scale 41).

Another method, the oscillation 111 measurement method, integrates a frame body on which the gyro body is suspended with a hanging wire into the theodolite, and places the gyro on the theodolite so that the optical image of the index is always at the reference point 0 of the scale 41. Rotate the theodolite like this and use the theodolite to track the movement of the gyro body caused by the preset.

In the 0-period measurement method, which measures the horizontal angle at which the maximum amplitude occurs and then determines the true north direction, twisting occurs in the suspension wire.
This method has the advantage that the rotation of the theodolite also rotates the gyro frame supporting the suspension line, so that the suspension line that suspends the gyro body is not twisted, and there is no error caused by the torsion torque of the suspension line.

(Problems to be Solved by the Invention) In all of the cases described above, individual differences remain in determining the maximum amplitude point of a slow-moving light image with a long period, and there are limits to measurement accuracy. be.

In addition, it is necessary to perform measurements over several cycles in order to obtain an average, which results in a longer measurement time.

This invention is a method for measuring true north using a gyro.
The aim is to automate measurements, shorten measurement time, and improve accuracy.

(Means for Solving the Problem) This invention provides a mirror on the gyro body suspended on a frame body, and reflects light from a light source on the mirror to enter the light receiving position detection sensor array, thereby controlling the gyro's presetting. A time-output curve is determined by the least squares approximation method from the output indicating the light receiving position of the detection sensor that changes over time.
The present invention is characterized in that the deviation between the reference position and the true north direction is determined based on the curve.

(Example) FIG. 1 is a schematic diagram of an apparatus for implementing the true north measuring method of the present invention.

A gyro 2 with a mirror 1 attached thereto is suspended from a frame 4 by a hanging wire 3, and is connected to a light source 5, a slit plate 6 with a slit serving as an index. Imaging lens group 8. A mirror 9 and a light receiver array 7 as a light receiving position detector are fixedly provided to the frame 4. The light emitted from the slit illuminated by the light source 5 is reflected by the reflection@9 and enters the gyro mirror 1, and the light reflected by the gyro mirror 1 is received by the reflecting mirror 6 as a light receiving position detection sensor. The image is formed on the device array 7.

This device is first set so that an image is formed approximately in the center of the photoreceiver array 7, and this direction is taken as temporary north. As the gyro 2 is preset, the optical image formed on the photoreceiver array 7 moves on the photoreceiver array 7. Each photoreceiver of the photoreceiver array 7 is connected to a position 1 time detector 12 via a preamplifier 10. A signal from a clock 11 is also input to the 0 position and time detector 12. Time is measured from the start of measurement to which photoreceptor in the array 7 to detect when the light is incident. Since the spacing between each photoreceiver on the photoreceiver array is known, the temporal change in the position of the optical image with respect to the reference position on the photoreceiver array 7 can be measured in this way.

Now, let us write (it t) to indicate that light is incident on the i-th photoreceiver in the photoreceiver array at time t.
x), (it1.t,), (it2.ta) (1+3
#tJ, (i + se ts), (it2゜ts
) If we obtain a measurement result like this, we plot the time on the horizontal axis as shown in Figure 2.

The light receiving position on the photoreceiver array is plotted on a graph with the vertical axis, and the sine curve is fitted using the least squares approximation method. Find the deviation Δα of the preset amplitude with reference to the installation position of the preset amplitude.

True north N can be found as follows.

N = NO+ (T11” /T3> ・Δα Where, No: Assumed north direction (direction in which the device was installed) Δα: Amount of left/right amplitude deviation To: Preset period T when there is no torsional torque on the hanging wire : When the suspension wire has torsional torque, calculations longer than the preset period are executed by the calculator 13, and the results of the calculations are automatically output.Actually.

K=T, "/T" is measured and given as a constant of the instrument.

(Effect of the invention) According to the present invention, as described in detail above.

The amount of deviation between the true north direction and the reference position (temporary north direction) is automatically determined, and the true north direction is determined. Therefore, measurement time is shortened and highly accurate measurement becomes possible.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing a device for implementing the true north measuring method of the present invention, Fig. 2 is an explanatory diagram showing the relationship between measurement data and a sine curve fitted thereto, and Fig. 3 is an explanation of a conventional example. 4 is a diagram showing the optical image of the index moving on the scale of the eyepiece, and FIG. 5 is a diagram showing the movement of the optical image of the index. The main symbols in FIG. 0 are as follows. 1.31: Gyro mirror 2.32: Gyro 3.34: Suspension wire 4.33: Frame 5.35: Light source 6.36: Slit 7: Receiver array 8.38: Imaging lens 9: Mirror 11: Clock 12: Position/time detector 13: Computer 37: Ibis 39: Focus plate patent issuer Sokkisha Co., Ltd. Applicant's agent Patent attorney Fumio Sato (and 2 others) Figure 1 Figure 2

Claims (1)

[Claims] A mirror is provided on the gyro body suspended from the frame, and the light from the light source is reflected by the mirror and incident on the light receiving position detection sensor array, thereby detecting the light receiving position of the detection sensor that changes over time due to the precession of the gyro. A true north measuring method characterized by determining a time-output curve from the output shown by a least squares approximation method, and determining a deviation between a reference position and a true north direction based on the curve.