JPH03187499A - Obstruction detecting device for excavating machine in civil engineering works - Google Patents

Abstract

PURPOSE:To prevent the reflection of electromagnetic waves and certainly catch the reflected wave from an obstruction in the propulsive direction by forming the part of the length range corresponding to the broadening angle of the electromagnetic waves from a transmitting and receiving antenna by use of a radio permeating material. CONSTITUTION:The part of the length range corresponding to the broadening angle of the electromagnetic waves from a transmitting and receiving antenna 4 is formed of a radio permeating material tube part 2 having a reguired mechanical strength and consisting of the same material as a front member 3 having a thickness L1 such as FRP materials. The tube part is regulated to a determined length to prevent the influence on the directional control of a civil excavator, and holds a strength sufficient to the earth pressure. Hence, the reflection of the electromagnetic waves around the front end surface of a propulsive tube and the tube part top end part is prevented, the electromagnetic waves are transmitted at a determined broadening angle frontward of the propulsive direction, and the reflection wave from an obstruction in the determined broadening angle can be certainly caught to improve the detecting ability.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) This invention relates to an obstacle detection device attached to an excavation propulsion machine for civil engineering work, and the invention relates to an obstacle detection device attached to an excavation propulsion machine for civil engineering work. It is designed to improve the detection ability of.

(Prior Art) Obstacle detection devices for civil engineering excavation propulsion machines receive reflected waves from obstacles by emitting electromagnetic waves into the soil.
It is designed to detect obstacles.

FIG. 4 shows a conventional example of such an obstacle detection device for a civil engineering excavation propulsion machine. In the same figure, 1 is the civil engineering excavation propulsion machine propulsion pipe (hereinafter simply referred to as the propulsion pipe), and in order to maintain the strength of the propulsion pipe so that it will not be damaged by the dirt, it is made of stainless steel, etc., which is the same as the casing of the civil engineering excavation propulsion machine. It is made of metal. In addition, the front member 3 at the tip of the propulsion tube 1
When metal is used, electromagnetic waves are reflected, making it difficult to detect obstacles, so radio wave transmitting materials with excellent electromagnetic wave transmission characteristics are used. As the radio wave transmitting material, an FRP material or the like having a relative permittivity that is approximately the same as the average relative permittivity of the soil is used, and it is formed to be appropriately thick so as to have the same mechanical strength as the metal propulsion tube 1. ing. Reference numeral 4 denotes a transmitting/receiving antenna, which is rotatable around the tube axis of the propulsion tube 1 by an antenna rotating section 5, and is given a constant inclination angle with respect to the tube axis. 6 is an antenna drive unit equipped with a motor and reduction gear means for rotating the transmitting/receiving antenna 4;
8 is a control unit that controls the rotation of the antenna, 8 is a propulsion direction control mechanism, 9 is an obstacle, 11 is a transmitted wave, and 12 is a reflected wave.

Then, the obstacle 9 is detected by transmitting electromagnetic waves forward in the propulsion direction of the civil engineering excavation propulsion machine and receiving reflected waves from obstacles, etc., which have different electrical characteristics (relative permittivity) from the soil. There is. At this time, by emitting electromagnetic waves while rotating the transmitting/receiving antenna 4, which is given a fixed angle of inclination, by the control unit 7 and the antenna driving unit 6, the obstacle 9
The reflected wave 12 is received from the ground to detect a wide range in front of the civil engineering excavation propulsion machine.

(Problem to be Solved by the Invention) In the conventional obstacle detection device for civil engineering excavation propulsion machinery, the transmitting/receiving antenna 4 is rotated with a fixed angle of inclination. Since it has an angle, electromagnetic waves emitted from the transmitting antenna part of the transmitting/receiving antenna 4 are radiated at a constant spread angle. For this reason, when electromagnetic waves hit the vicinity of the tip of the propulsion tube 1 made of metal, reflections that adversely affect obstacle detection occur. In other words, the conventional obstacle detection device for civil engineering excavation propulsion machinery does not have a structure that prevents reflection from the vicinity of the tip of the propulsion tube 1 due to the spread of electromagnetic waves, so when detecting the obstacle 9, As shown in FIG. 5, the received waveform of is, when the vertical axis is the reflection time, a reflected wave R is generated from the metal part of the tip of the propulsion tube 1 connected to the front member 3 made of radio wave transparent material. This results in multiple reflections,
This affects the received waves from the original obstacle 9. Therefore, in the same figure, the reflected wave P from the obstacle 9 that should be at the position of the arrow overlaps with the reflected wave R from the metal part near the tip of the tube part of the propulsion tube 1, and the reflected wave P from the obstacle 9 overlaps with the reflected wave R from the metal part near the tip of the propulsion tube 1. There was a problem in that it became difficult to detect the obstacle 9 because it became impossible to distinguish between the obstacles.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an obstacle detection device for a civil engineering excavation propulsion machine that can improve the obstacle detection ability by preventing the reflection of electromagnetic waves from the front end surface of the propulsion tube as well as from the vicinity of the tip of the tube. shall be.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, the present invention provides a structure in which a tip of a propulsion pipe in a civil engineering excavation propulsion machine that excavates and propels underground is provided with a predetermined extension in the forward direction of propulsion. An obstacle detection device for a civil engineering excavation propulsion machine, which is equipped with a transmitting/receiving antenna that transmits electromagnetic waves at an angle and receives reflected waves from obstacles, the device comprising: The gist is that the corresponding portion of the pipe portion within a predetermined length range is formed of a radio wave transparent material having a required mechanical strength.

(Function) Based on the conditions that the detection device body does not become larger than necessary and does not affect the direction control of the civil engineering excavation propulsion machine, a predetermined length corresponding to the spread angle of electromagnetic waves from the tip of the propulsion tube is determined. A portion of the tubular portion of the range is made of a radio wave transparent material having the required mechanical strength. Therefore, reflection of electromagnetic waves near the front end surface of the propulsion tube and the tip of the tube is prevented, and the electromagnetic waves are transmitted forward in the propulsion direction at a predetermined spread angle, and reflected waves from obstacles within this predetermined spread angle range are prevented. is reliably captured, and the ability to detect obstacles is significantly improved.

(Example) Hereinafter, an example of the present invention will be described based on FIGS. 1 to 3.

In FIG. 1, the same or equivalent components as those in FIG. 4 are designated by the same reference numerals, and redundant explanation will be omitted.

In this embodiment, a length range from the tip of the propulsion tube 1 corresponding to the spread angle of electromagnetic waves emitted from the transmitting antenna part of the transmitting/receiving antenna 4 is made of the same material as the front member 3 with a thickness Ll. It is formed of a tube section 2 made of radio wave transparent material. This radio wave transparent material pipe part 2 is designed to prevent the main body of the device from becoming unnecessarily thick by attaching a member made of radio wave transparent material to the tip of the propulsion tube, and to prevent it from affecting the direction control of the civil engineering excavation propulsion machine. Based on the two conditions of not making the tip heavier by adding a longer length than necessary, the following length range is specified.

In other words, when the transmitting/receiving antenna 4 is rotated with a constant inclination angle φ relative to the tube axis of the propulsion tube 1, the electromagnetic waves emitted from the transmitting antenna part will be caused by the inclination angle φ and the directivity of the transmitting/receiving antenna 4. It is emitted with a spread corresponding to the Here the first
As shown in the figure, the maximum diameter of the transmitting/receiving antenna 4 is t, and the spread angle of the electromagnetic waves radiated from the transmitting antenna section is θ,
If the angle of declination that the antenna rotating section 5 makes with the tube axis of the propulsion tube 1 is φ, and the inner diameter of the tip of the propulsion tube 1 is r, then the electromagnetic waves emitted from the transmitting antenna section will have an angle of 9 from near the tip of the propulsion tube.
- The length L2 of the radio wave transmitting material tube part 2 to avoid receiving I is set in the range of L2>LM. L here
M is determined by the following formula.

LM= [r (t/2) X C□Sφ]×[
・l/lanφ−1/jan(φ+θ)]...(1) Therefore, a part of the tip of the metal propulsion tube was made of radio wave transparent material based on the formula (1) and the strength of the propulsion tube according to Tonosho. By making the radio wave transmitting material pipe part 2 have a certain length and thickness, it is possible to maintain sufficient strength against earth pressure and prevent reflection of electromagnetic waves from near the tip of the pipe part of the propulsion pipe. I can do it.

In the obstacle detection device for civil engineering excavation propulsion machinery of this embodiment, the front end face of the propulsion pipe and a part of the tip of the pipe part are made of a radio wave transparent material such as FRP material by the front member 3 and the radio wave transparent material tube manufacturing part 2. Because of this, reflection of electromagnetic waves at the tip of the propulsion tube is prevented, and reflected waves from obstacles can be reliably captured, making it possible to improve detection ability.

FIG. 2 shows the received waveform of the receiving antenna section of the transmitting/receiving antenna 4. As shown in FIG.

Figure 2 (a) shows the reflected wave P from a 75mmφ steel pipe placed as an obstacle in the ground 70cm in front of the detector, and when the transmitting/receiving antenna 4 is fixed at a certain rotation angle. This is the received waveform of the reflected wave P. The reflected wave P from this steel pipe can be confirmed from the following equation regarding the propagation speed of electromagnetic waves.

VC/ε'4...
・(2>T-2L・ε鴫/C...(3) Where, v: Speed of electromagnetic wave in the medium, C: Previous speed, ε: Relative permittivity in medium, T: Electromagnetic wave's Round trip time, L: distance to buried object.

That is, the position of the steel pipe in the soil can be confirmed by calculating the round trip time T of the electromagnetic waves according to equation (3).

FIG. 2(b) shows the reflected waves from the steel pipe when the antenna is rotated 360' and reflection information from the soil is collected every 2 degrees. At this time, the reception intensity of the reflected wave from the buried steel pipe becomes maximum when the transmitting/receiving antenna 4 is horizontally polarized with respect to the buried steel pipe. Therefore, when the transmitting/receiving antenna 4 is rotated, reflected waves from the steel pipe are obtained at two positions for each phase of 180° as shown in the figure.

In addition, Figure 3 shows the reflected wave R from the metal part of the propulsion tube 1 when a 75mmφ steel pipe is placed in the mountain sand 7Qcm in front of the detection device and the length of the radio wave transmitting material tube section 2 is changed. ，
and the peak value of the reflected wave P1 from the steel pipe are each expressed in decibels. In this case, even if the vicinity of the tip of the propulsion tube is replaced with a radio wave transparent material and the length is changed, the front 7
The intensity of the reflected wave P1 from the 75 mmφ steel pipe located at the 0 cm position shows approximately the same level. However, in the range of L2 to LM, the level of the reflected wave R1 from the metal part of the propulsion tube is the reflected wave P of the 75 mmφ steel pipe.

Since the difference in reflection from the steel pipe when the transmitting/receiving antenna 4 is rotated cannot be detected by horizontal detection, the reflected wave from the steel pipe cannot be captured. On the other hand, when the length of the metal part of the propulsion tube is in the range L2 > LM, the strength of the opposite wave R1 from the metal part of the propulsion tube becomes weaker, and the influence on the reflected wave P1 from the 75mmφ steel pipe becomes smaller. It is possible to reliably capture the reflected wave P. Therefore, by making the tube section 2 of the propulsion tube made of a radio wave transparent material with a length that satisfies L2 > LM shown by equation (1), noise due to reflection from the metal part of the propulsion tube can be reduced, and the tip It is possible to improve the reception level of reflected signals from obstacles in front of the unit, and it is possible to significantly improve detection ability.

[Effects of the Invention] As explained above, according to the present invention, the portion of the tube part within a predetermined length range corresponding to the spread angle of electromagnetic waves from the front end face and tip of the propulsion tube is exposed to radio waves having the required mechanical strength. Since it is made of a transparent material, reflection of electromagnetic waves near the front end surface of the propulsion tube and the tip of the tube part is prevented, and the electromagnetic waves are transmitted forward in the propulsion direction at a predetermined spread angle, and obstacles in this predetermined spread angle range are prevented. This has the advantage that reflected waves from objects can be reliably captured and the ability to detect obstacles can be significantly improved. Therefore, it is possible to prevent damage to buried objects caused by the underground excavation propulsion machine or damage to the underground excavation propulsion machine due to obstacles, and to advance excavation while avoiding obstacles by detecting obstacles in advance. This will greatly contribute to improving the construction quality of civil engineering works.

[Brief explanation of drawings]

1 to 3 show an embodiment of the obstacle detection device for a civil engineering excavation propulsion machine according to the present invention, and FIG. 1 shows the structure of the tip of the civil engineering excavation propulsion machine in which the detection device is installed. The configuration diagram, Fig. 2 is a detection characteristic diagram showing waveform examples of reflected waves from obstacles, etc., and Fig. 3 shows reflected waves from obstacles and propulsion when the length of the pipe made of radio wave transparent material is changed. A characteristic diagram showing the received intensity of the reflected wave from the pipe metal part, Fig. 4 is a configuration diagram showing a conventional obstacle detection device for civil engineering excavation propulsion machinery, and Fig. 5 is a waveform diagram showing the received waveform by the above conventional example. be. 1: Civil engineering excavation propulsion machine propulsion tube, 2: Pipe section made of radio wave transparent material, 3: Front member made of radio wave transparent material, 4: Transmission/reception antenna, 9: Obstacle.

Claims (1)

[Scope of Claims] A transmitting/receiving antenna that transmits electromagnetic waves at a predetermined spread angle forward in the propulsion direction and receives reflected waves from obstacles, at the tip of a propulsion tube in a civil engineering excavation propulsion machine that excavates and propels underground. An obstacle detection device for a civil engineering excavation propulsion machine, which has a front end surface and a tip of the propulsion tube within a predetermined length range corresponding to the expansion angle, and has a required mechanical strength. An obstacle detection device for a civil engineering excavation propulsion machine, characterized in that it is formed of a radio wave transparent material.