JPH05196727A - Underground radar having arbitrary-curve searching function - Google Patents

Abstract

PURPOSE:To obtain the coordinates data of the moving point by obtaining the difference between the numbers of rotations of the right and left wheels of a truck, and obtaining the moved distance and the advancing angle based on the difference and the number of rotations of one wheel. CONSTITUTION:Rotary encoders 1 and 2 are provided on the right and left wheels of a truck. The encoder 1 is connected to the up-counting terminal of a counter 3, and the encoder 2 is connected to the down-counting terminal of the counter 3 and a signal processor 4. The counter 3 counts the difference between the numbers of rotations of the right and left wheels and outputs the difference into the processor 4. The processor 4 can obtain the actually moved locus based the traverse pich and the treads of both wheels derived from the output signal of the encoder 2 and the counter 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an underground radar with an arbitrary curve search function for searching underground buried objects from the ground.

[0002]

2. Description of the Related Art Conventionally, various methods have been proposed for exploring buried objects in the ground, but basically, pulse waves such as electromagnetic waves or ultrasonic waves are emitted into the ground and reflected from the buried objects. It depends on the method of detecting the reflected waves that have been received.

This device mounts an underground radar device on a carriage and emits radio waves toward the ground while moving,
If there is a discontinuous portion in the ground, for example, a boundary between strata or an embedded object, radio waves are reflected from the boundary, so that the state of the ground can be known by detecting reflected radio waves.

[0004]

However, since such a conventional apparatus does not have a function of detecting position information when arbitrarily moving a place, the carriage must be moved linearly, for example, a manhole. When exploring the buried objects around, it was necessary to go back and forth over the plane including the manhole many times, and collect the necessary information, which was a problem that it took a very long time. ..

The present invention has been made in view of such circumstances, and provides an apparatus capable of obtaining coordinate information of a moving point by knowing information on the rotational speed difference between left and right wheels.

[0006]

In order to solve such a problem, the present invention provides a first pulse generator for generating a number of pulses corresponding to the number of rotations of a wheel on the left side of a truck, and a wheel on the right side of a truck. A second pulse generator for generating a number of pulses corresponding to the number of revolutions, and a generated pulse number difference detection for detecting a difference between a pulse generated by the first pulse generator and a pulse generated by the second pulse generator Means and first or second
And a position coordinate calculating means for obtaining absolute position coordinates from the number of pulses generated from the pulse number generator and the output of the generated pulse number difference detecting means.

[0007]

[Operation] By obtaining the rotational speed difference between the left and right wheels of the bogie, the rotational information of the bogie can be known, and the traveling distance and the traveling angle can be known from the rotational information and the rotational speed of one wheel. The movement coordinates can be calculated moment by moment.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an embodiment of the present invention, and shows a position coordinate detecting portion of a carriage on which an antenna and a radar device (not shown) are mounted. In FIG. 1, a left wheel rotary encoder (first pulse generator) 1 for generating a pulse number corresponding to the rotation speed is provided on the left wheel of the truck, and a right wheel is provided with a pulse number according to the rotation speed. A right side wheel rotary encoder (second pulse generator) 2 is provided, one of which is an up-count signal input terminal of an up-down counter 3 (generated pulse number difference detection means), and the other is a down-count signal input terminal. It is connected to the.

One of the two rotary encoders, in this example, the output of the right wheel rotary encoder 2 and the output signal of the up / down counter 3 are connected to a signal processor (position coordinate calculating means) 4 and supplied. The absolute position coordinates are calculated based on the signal of.

In the apparatus constructed as described above, when the carriage is pushed to move the antenna, pulses are generated from the rotary encoders 1 and 2 mounted on the left and right wheels.
When the truck is moving on a straight line, the output signals of the up / down counter 3 do not change because the number of pulses generated from the left and right rotary encoders is the same. However, when the curve is measured, the rotation speed of the right wheel and the rotation speed of the left wheel are different, so the up / down counter 3 outputs an output corresponding to the difference and to the right or left. Generate a signal.

In the signal processor 4, the traverse pitch Δx and the locus actually moved from the tret L of both wheels can be obtained from the output pulse of the rotary encoder 2 for the right wheel and the output signal of the up / down counter 3.

Next, how to obtain the movement locus will be described. As shown in FIG. 2, wheels are attached to the respective vertices of an equilateral triangle ABC, and the loci of the rear wheels A and B are curves 1 and 2, respectively. Letting x and y be the stationary system, the locus of the center (center of gravity) of ΔABC (that is, the antenna part) is determined as follows.

The unit tangent vector at point A on curve 1 ist
(Underlined letters represent vectors ...
・ Although vectors are not originally underlined, they are electronic
The application allows the use of vector characters in the text
Because there is no, underline only in the text vector
Express that. Therefore, in the formulas and drawings
Uses vector characters, but this is underlined
(Meaning the same as the one with), unit normal vector
TonWhen (A → B direction), the equation (1) is established.

[0014]

[Equation 1]

Where S represents the length along curve 1, k
Is the curvature. This curvature k is related to the difference in rotation of the wheels attached to A and B as follows. When the position vector of the point B is Y and AB = 1, the equation (2) is obtained.

[0016]

[Equation 2]

Differentiating this with respect to S yields the equation (3).

[0018]

[Equation 3]

Letting S ′ be the length along the curve 2, A, B
Since the wheels at the points are parallel, the formula is as shown in equation (4).

[0020]

[Equation 4]

When the equation (3) is used, the equation (5) is obtained.

[0022]

[Equation 5]

If ΔS is the difference between the moving distances of the wheels in A and B, then S '= S + ΔS. Therefore, from equation (5), (6)
The formula is obtained.

[0024]

[Equation 6]

The left side of the equation (6) is the difference between the moving distances of the wheel B and the wheel A when the wheel A travels a unit length, and the output pulse numbers n _A and n _B (wheels A and B) of the rotary encoder are immediately obtained.
The number of pulses output from the rotary encoder of (1) is defined as n _A and n _B ), and equation (7) can be obtained.

[0026]

[Equation 7]

Since the curvature can be obtained from the equation (6) (or the equation (7)), the differential equation of the equation (1) can be numerically integrated.

[0028]

[Equation 8]

The locus of the center of gravity G can be obtained by the equation (9).

[0030]

[Equation 9]

From the above, the locus of the center G of the antenna part and the rotation amount θ (the angle formed by the x axis and the vector) with respect to the stationary system can be obtained. By applying this angle difference θ to the equation (12) described later, the scattering matrix in the xy system can be obtained.

Even if the measurement is performed on the curved line in this way, the absolute direction of the buried pipe can be obtained because the data can always be converted into data for the stationary system.

By mounting this device on a radar and performing processing simultaneously with the radar signal, both the underground information and the moving trajectory can be displayed at the same time, as shown in FIG. The display on the left side of FIG. 3 shows the underground condition, and the display on the right side shows the movement trajectory.

Although the above description is the gist of the present invention, this device can know the position coordinates even if the carriage is moved along a curved course. When conducting an exploration along an underground buried object, the exploration is often performed while curving, which is particularly effective for such an application. In order to carry out the exploration along the underground buried object, it is suitable to perform the exploration while rotating the coordinates, which will be described below.

FIG. 4 is a plan view showing the structure of the antenna used in this apparatus. In the figure, 7 to 9 are dipole antennas each having a triangular metal plate as an element and having their vertices opposed to each other. Each dipole antenna has a polarization plane indicated by an arrow, and a point A outside the antenna is provided.
Is arranged with the plane of polarization shifted by 120 degrees as shown in the figure and rotated.

FIG. 5 shows a radar device which transmits and receives radio waves via this antenna. In the figure, reference numerals 1 and 2 denote rotary encoders, which generate a distance pulse as shown in FIG. 6A each time the vehicle travels a predetermined distance. 1
1 is a twin encoder circuit (consisting of the up / down counter 2 and the signal processor 4 in FIG. 1), 12 is a radar controller that controls the whole, 13 is a transmission circuit that transmits radio waves, and 14 is a reflected wave from the ground. Receiver circuit for demodulation, 2
Reference numeral 5 is a signal processor that performs predetermined signal processing based on signals supplied from both the radar controller 12 and the wave circuit 14 to collect information about underground buried objects, and 16 is one of the antennas 7 to 9 which will be described later. To the transmitter circuit 13,
A polarization switching circuit for connecting the other one to the receiving circuit 14,
And 21 are wheels.

The operation of the apparatus thus configured is as follows. As the device travels, the rotary encoders 1 and 2 attached to the wheels 20 and 21 generate distance pulses as shown in FIG. 6 (a). The distance pulse is supplied to the radar controller 12 via the twin encoder circuit 11, and under the condition that the period T is longer than a certain value, three polarization switching is performed during the period as shown in FIG. 6 (b). Pulses are sequentially generated. This pulse is the polarization switching circuit 1
As shown in Table 1, the polarization switching circuit 16 supplied to 6 sequentially selects two antennas out of the antennas 7 to 9, one for reception and the other for transmission.

[0038]

[Table 1]

In Table 1, the transmitting antenna and the receiving antenna may be reversed. Further, the other two antennas not used for transmission may be simultaneously used to combine the two signals.

Therefore, each time the switching pulse is generated, the transmitting antenna and the receiving antenna are switched. Then, the radar controller 12 controls the transmission wave circuit 13 as shown in FIG. 6C for a predetermined time after the switching pulse is generated to transmit the radio wave. Then, the reception wave circuit 14 is controlled simultaneously with the transmission of the radio wave, and the reception wave circuit 14 is operated for a predetermined time. The transmission and reception times are set shorter than the time until the next switching pulse is generated.

In this way, the polarization of the transmission rotates every 120 degrees, and the polarization of the reception also has a phase difference of 120 degrees with this.
Since it rotates every 20 degrees, radio waves are transmitted in all directions and reflected waves are received in all directions. Therefore, in the conventional device, the polarization direction was fixed, so it could be difficult to detect depending on the embedding direction.However, this device detects the embedding object in any embedding direction because the polarization direction changes from moment to moment. can do.

The signal demodulated by the receiving circuit 14 and the signal from the twin encoder circuit 11c are the radar controller 1
2, electrical / optical conversion unit 22, optical fiber cable 2
3. Signal processor 25 through the optical / electrical conversion unit 24
Information of the buried object corresponding to the distance is detected. Even if the signal obtained from the receiving antenna is used as it is, the desired purpose can be achieved because the polarization direction rotates, but by calculating the scattering matrix in the signal processor 15 as follows, Further efficient detection can be performed.

Assuming the x and y axes orthogonal to the ground surface, the radar transmission and reception signals have the following scattering matrix relationship. In the formulas shown below, those with dotted underlines represent matrices, and those without underlines represent scalar quantities. Although it is anomalous in relation to the format, it is described with an underline).

S = Sij (t) (10) where i and j are components in the x or y direction, and (1
Expression (0) can be expanded as expression (11).

[0045]

[Equation 10]

Here, S11 is a component that emits radio waves of x-direction polarization and detects reflected waves of x-direction polarization, S12 is a component that emits radio waves of x-direction polarization and detects reflected waves of y-direction polarization, and S21. Is y
S22 is a component that emits a directional polarized radio wave and detects a reflected wave of the x direction polarized wave, and S22 is a component that emits a radio wave of the y direction polarized wave and detects a reflected wave of the y directional polarized wave.

The components from S11 to S22 must be obtained from the radar reception signal. Although the description of the guidance process is omitted because it becomes complicated, the conclusion is that the radar reception signals in modes 1, 2, and 3 are f1 (t), f2 (t), and f, respectively.
If it is 3 (t), the signal processor 15 may perform the calculations of the expressions (3) to (6). S11 (t) =-{f1 (t) + f3 (t)} ... (13) S12 (t) =-{f1 (t) + 4f2 (t) + f3 (t)} / 3 ... (14) S21 (t) = S12 (t) ... (15) S22 (t) = {f1 (t) -f3 _{^{(t)} / 3 1/}} 2 ········ (16)

Of the respective components of the scattering matrix thus obtained, the polarization directions of the transmitted and received radio waves are the same S11
(T) and S22 (t) are suitable for the measurement of buried objects having no directional component in the ground, that is, those having omnidirectional components such as formations or cavities. In addition, S12 (t) and S21 in which the polarization directions of the transmitted and received radio waves are orthogonal
(T) is suitable for measuring a buried object in the ground having a specific directional component, that is, a buried pipe.

When investigating the buried pipe, it is uncertain in which direction the buried pipe is buried. For example, in the state where the polarization direction of the transmitted radio wave and the buried direction of the buried pipe are orthogonal, Does not reflect from the buried pipe, the reflected wave cannot be detected. Further, when the polarization direction of the transmitted radio wave is parallel to the embedding direction of the buried pipe, the polarization direction of the received radio wave is orthogonal to the reflected wave in the radio wave reception direction, and thus the reflected wave cannot be detected. To this end, if the polarization direction of the radio wave and the buried direction of the buried pipe are kept at 45 degrees, the maximum reception level can be obtained.

For this purpose, the scattering matrix may be coordinate-converted. That is, the calculation of the equation (12) may be performed.

[0051]

[Equation 11]

Thus, by obtaining the data obtained by rotating the received scatter vector data by an arbitrary angle θ, the received data can be obtained regardless of the embedding direction of the embedding pipe. Therefore, when measuring, collect the received data without considering the buried direction of the buried pipe, and search for an angle that maximizes the signal obtained while changing the angle θ during analysis, and obtain a signal with a good S / N ratio. can get.

[0053]

As described above, according to the present invention, the position coordinates can be known on the basis of the left and right wheel rotation speed information, so that an arbitrary movement route can be taken and an underground buried object can be efficiently used. It has the effect that the exploration of

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a diagram for explaining a method of calculating a movement track.

FIG. 3 is a diagram showing an example of a display screen of an apparatus to which the present invention has been applied.

FIG. 4 is a diagram showing an array state of antennas.

FIG. 5 is a block diagram showing the configuration of the entire radar device.

FIG. 6 is a diagram showing a waveform of each part.

[Explanation of symbols]

 1, 2 rotary encoder 3 up-down counter 4 position coordinate calculation means 11 rotary encoder 12 radar controller 13 wave transmission circuit 14 wave receiving circuit 15 signal processor 16 polarization switching circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Noriaki Kimura 3-16-1, Tambara, Tamano-shi, Okayama Mitsui Engineering & Shipbuilding Co., Ltd. Tamano Research Institute (72) Inventor Kanji Murasawa 3-16, Tambara, Tamano-shi, Okayama No. 1 Mitsui Engineering & Shipbuilding Co., Ltd. Tamano Research Institute (72) Inventor Chihiro Kamimuta 3-161-1 Tambara, Tamano City, Okayama Prefecture Mitsui Shipbuilding Co., Ltd. Tamano Research Laboratory (72) Inventor Massei Konishi 3 Tamahara, Tamano City, Okayama Prefecture No. 16-1 Mitsui Engineering & Shipbuilding Co., Ltd. Tamano Research Institute

Claims (1)

[Claims] 1. In an underground buried object exploration radar that detects a state of the underground by a signal reflected from the ground while transmitting a radio wave while mounting a transmission antenna on the carriage and moving the left side of the carriage. First pulse generator that generates a number of pulses corresponding to the number of wheel rotations of the vehicle, a second pulse generator that generates a number of pulses corresponding to the number of wheel rotations on the right side of the bogie, and a first pulse generation Generated pulse number difference detecting means for detecting a difference between a pulse generated by the device and a pulse generated by the second pulse generating device, and detecting the number of pulse generated by the first or second pulse number generating device and the generated pulse number difference A subsurface radar with an arbitrary curve exploration function, comprising: position coordinate calculation means for obtaining absolute position coordinates from means output.