JPH1095338A - Pseudo radar type obstacle detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pseudo radar type obstacle detecting device accurately detecting an obstacle. SOLUTION: In an obstacle detecting device laying a leakage transmission path along a road or line in both sides thereof emitting a radio wave from one leakage transmission path 1 to the other leakage transmission path 2 to detect an obstacle, to one end of one leakage transmissions path 1, a transmitter 3 generating a pulse-state signal is connected, also to one end of the same side of the other leakage transmission path 2, a receiver 4 receiving a signal delayed in accordance with a position of the pulse-state signal is connected, and in this receiver 4, a filter 7 taking out an envelope from a signal waveform is connected, a memory device 5 storing an envelope of a signal waveform previously without an obstacle is provided, an arithmetic device 6 is provided, which detects a position of the obstacle from a differential waveform between the envelope without this obstacle and the envelope taking out the filter 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an obstacle detecting device utilizing a leaky transmission line such as a leaky coaxial cable or a leaky waveguide, and more particularly to a simulated radar type obstacle detecting device for accurately detecting an obstacle. It is about.

[0002]

2. Description of the Related Art In a railway, it is necessary to detect an obstacle on a track as soon as possible and to immediately remove the obstacle in order to operate the train normally and prevent an accident. Further, in order to prevent a rear-end collision accident or a double accident on an expressway, it is necessary to detect a falling object from a truck or the like, an emergency stop vehicle, or an accident vehicle and notify the following vehicle.

[0003] From such a need, as an obstacle detecting device for continuously detecting an obstacle on a road or a track, a device utilizing a leaky transmission line such as a leaky coaxial cable or a leaky waveguide has been developed. I have. In these leaky transmission lines, slots for leaking and radiating radio waves are arranged at appropriate intervals in the longitudinal direction of the conductor.Since leaky coaxial cables and leaky waveguides are in principle the same, Now, an apparatus using a leaky coaxial cable (hereinafter referred to as LCX) will be described.

[0004] As shown in FIG. 3, an obstacle detecting device includes, for example, a transmission LCX1 laid on one side of a road, a reception LCX2 laid on the opposite side of the road, and a transmission LCX2.
A signal generator (transmitter) 3 that is connected to one end (near end) of X1 and generates a pulse-modulated signal, and is connected to one end (near end) of the reception LCX2 on the same side as the signal generator 3 and And a receiver (receiver) 4 for receiving a signal. An anti-reflection terminator is connected to each of the far end of the transmission LCX1 and the far end of the reception LCX2.

[0005] The signal generator 3 generates a pulse-modulated signal as shown in FIG.
It is incident on X1. This pulse-like signal is transmitted by the transmission LCX
Are sequentially radiated as radio waves from the slots arranged in the longitudinal direction. This radio wave is transmitted to the receiving LC opposite to the transmitting LCX1.
The signal incident from each slot of X2 and incident on the receiving LCX2 is received by the receiver 4.

If there is no obstacle between the transmission LCX1 and the reception LCX2, the radio wave radiated from the transmission LCX1 by the pulse-like signal generated by the signal generator 3 is delayed by a delay time corresponding to the slot position. Via receiver 4
Is received. As shown in FIG. 4B, this signal waveform is a waveform in which the original pulse-like signals are sequentially superimposed by the delay time of each slot.

When there is an obstacle, the radio wave is shielded by the obstacle, so that the intensity of the received signal is low at the position where the obstacle exists. Therefore, as shown in FIG. 4C, the magnitude of the intensity is seen in the waveform of the received signal at the time corresponding to the position of the obstacle. In this way, the position of the obstacle can be obtained from the signal waveform.

[0008]

The prior art has the following problems.

In an apparatus using a leaky transmission line such as an LCX or a leaky waveguide, the coupling loss between the leaky transmission lines is not uniform in the longitudinal direction, so that the intensity of the received signal is not uniform. For this reason, if an attempt is made to detect an obstacle based on the magnitude of the signal waveform intensity, the signal intensity is reduced even if there is no obstacle depending on the position.

If a parabolic antenna is used outside the leaky transmission line, it is possible to make the intensity of the received signal uniform. However, in order to obtain a uniform waveform, the adjustment of the antenna is delicate, and since the antenna is installed along the leaky transmission line, the device becomes large-scale, so it is necessary to lay it next to the road or track. Is not realistic.

It is an object of the present invention to solve the above-mentioned problems and to provide a pseudo radar type obstacle detecting device for accurately detecting an obstacle.

[0012]

In order to achieve the above object, according to the present invention, a leaky transmission line is laid on both sides of a road or a railway, and radio waves are transmitted from one leaky transmission line to another leaky transmission line. In the obstacle detecting device for detecting an obstacle by radiating a signal, a transmitter for generating a pulse-like signal is connected to one end of one of the leaky transmission lines, and the pulse-like signal is connected to one end of the other side of the leaky transmission line on the same side. Is connected to a receiver that receives a signal delayed according to the position, and further connected to this receiver is a filter that extracts an envelope from the signal waveform, and stores an envelope of the signal waveform when there is no obstacle in advance. A device is provided, and an arithmetic unit for detecting the position of an obstacle is provided from a difference waveform between the envelope when there is no obstacle and the envelope extracted by the filter.

The arithmetic unit may normalize the differential waveform with an envelope when there is no obstacle, and detect the position of the obstacle from the waveform.

[0014]

An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

As described above, since the LCX and the leaky waveguide are basically the same, an apparatus using the LCX will be described here.

As shown in FIG. 1, a pseudo radar type obstacle detecting device according to the present invention comprises, for example, a transmitting LCX1 laid on one side of a road and a receiving LCX1 laid on the opposite side of the road.
X2 and a signal generator (transmitter) 3 connected to one end (near end) of the transmission LCX1 to generate a pulse-modulated signal
And a receiver (receiver) 4 connected to one end (near end) on the same side of the reception LCX 2 to receive the signal, and an envelope (hereinafter referred to as an envelope) based on a waveform of the reception signal included in the receiver 4. ) To extract a low-pass filter (hereinafter, LP)
F) 7, a storage device 5 for storing the envelope of the signal waveform, and an envelope stored in the storage device 5 and L
The arithmetic unit 6 detects the position of an obstacle using the envelope output from the PF 7. Transmit LC
A non-reflection terminator is connected to each of the far end of X1 and the far end of receive LCX2.

As shown in FIG.
The pulse-like signal shown in FIG.
Is incident on. The pulse signal is sequentially radiated as radio waves from each slot arranged in the longitudinal direction of the transmission LCX1. This radio wave is transmitted to the receiving LCX2 opposite to the transmitting LCX1.
, And the signal that has entered the receiving LCX 2 is received by the receiver 4.

The signal waveform received by the receiver 4 is shown in FIG.
As shown in FIG. 2A, the envelope extracted through the LPF 7 becomes as shown in FIG. 2B. When the envelope of the signal waveform is extracted without using the LPF 7, when performing the subsequent calculation, the difference result or the division result does not indicate the actual obstacle position due to the phase shift of the carrier wave when received. There is. For this reason,
It is good to take out the envelope with LPF7. Note that L
The cut-off frequency fc of the PF7 is obtained by setting the length of the obstacle to L, LCX
When the propagation speed of the signal in the equation is c ′, it is desirable to satisfy fc> c ′ / 2L.

The storage device 5 previously stores the envelope of the signal waveform when there is no obstacle. This envelope is used as a reference waveform.

The arithmetic unit 6 obtains a difference waveform between the envelope of the signal waveform and the reference waveform every time the envelope of the signal waveform is obtained. If there are obstacles,
Since the radio wave is shielded at that position, the reception intensity at that position decreases by a certain ratio regardless of the magnitude of the intensity. Therefore, the position of the obstacle appears in the differential waveform. Further, by dividing the difference waveform by the reference waveform and normalizing the waveform, a waveform as an attenuation ratio can be obtained. It is possible to remove the magnitude of the reception intensity due to the difference in the coupling loss in the longitudinal direction and the influence of the surroundings, and it is possible to obtain clear positional information.

[0021]

The present invention exhibits the following excellent effects.

(1) Obstacles are detected using the waveform when there is no obstacle as a reference waveform, so that the detection is not affected by the difference in coupling loss and the obstacle can be accurately detected without using an auxiliary device or ancillary equipment. Can be detected. Further, the influence of the difference in the waveform depending on the laying position can be eliminated.

(2) Since the difference waveform is normalized by the envelope when there is no obstacle, the difference in the coupling loss in the longitudinal direction and the magnitude of the reception intensity due to the influence of the surroundings are removed, thereby preventing erroneous detection and accurately. Location information can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram of a pseudo radar type obstacle detection device according to an embodiment of the present invention.

FIG. 2 is a waveform diagram showing (a) a signal waveform received by a receiver and (b) a waveform of an extracted envelope in the present invention.

FIG. 3 is a block diagram of a conventional obstacle detection device.

FIG. 4A is a waveform diagram showing a waveform of a transmission signal, and FIGS. 4B and 4C are waveform diagrams showing signal waveforms received by a receiver.

[Explanation of symbols]

 Reference Signs List 1 transmission LCX (leakage transmission line) 2 reception LCX (leakage transmission line) 3 signal generator (transmitter) 4 receiver (receiver) 5 storage device 6 arithmetic unit 7 low-pass filter

Claims (2)

[Claims] 1. A leaky transmission line such as a leaky coaxial cable or a leaky waveguide is laid along both sides of a road or a railway,
In an obstacle detection device that detects an obstacle by radiating radio waves from one leaky transmission line to the other leaky transmission line, a transmitter that generates a pulse signal is connected to one end of one leaky transmission line and the other is connected. At one end of the same side of the leaky transmission line, a receiver for receiving a signal obtained by delaying the pulse-like signal according to the position is connected, and a filter for extracting an envelope from the signal waveform is connected to this receiver, and an obstacle is previously set. A storage device for storing an envelope of a signal waveform when there is no obstacle, and an arithmetic unit for detecting a position of an obstacle from a difference waveform between the envelope when there is no obstacle and the envelope extracted by the filter is provided. A pseudo radar type obstacle detection device, characterized in that: 2. The quasi-radar obstacle according to claim 1, wherein the arithmetic unit normalizes the differential waveform with an envelope when there is no obstacle and detects the position of the obstacle from the waveform. Object detection device.