JP2005156360A - Approach detection device and approach detection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an approach detection device capable of detecting a detection object sufficiently at the safe separation distance between a transmission line and a crane without shortening the detection distance, even when linear body having a long and narrow shape with a narrow area or width such as an overhead transmission line is the detection object, and outputting a signal having a larger amplitude than a supply voltage from a transmitter when driven by a battery. <P>SOLUTION: A pulse signal having an amplitude on both positive side and negative side is generated at fixed time intervals by a transmission circuit 21, and amplified by an amplifying circuit 23. Then, the positive side signal and the negative side signal relative to the amplitude of the pulse signal are separated by a separation circuit 25, and the amplitude of the minus side signal is inverted by an inverting circuit 27 and added to the plus side signal by an adding circuit 29, and thereby a transmission signal having increased output is transmitted to an obstacle. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an approach detection device and an approach detection method for detecting an approach when a power transmission line and a crane approach each other mainly for a crane working under an overhead power transmission line.

  Monitoring of the approach of a crane under an overhead power transmission line is generally performed by visual monitoring with safety observers on site, but visual monitoring is very fatigued and difficult to monitor accurately for a long time. Because there is, it is difficult to respond. On the other hand, as an approach monitoring method using an apparatus, an ITV camera is installed on the site and an approach such as a transmission line and an obstacle is detected by image processing, or a proximity sensor such as an ultrasonic sensor is used as a boom tip or the like. A method of detecting the approach of an obstacle (such as a bridge or a building wall) and a crane attached to the vehicle has been proposed.

  As a detection method using a proximity sensor such as an ultrasonic sensor, there are methods described in Patent Documents 1 to 3.

  In the detection method described in Patent Document 1, an ultrasonic sensor is attached to the tip of a crane boom, a transmitter and a receiver are both attached, a transmission signal is output from the transmitter, and a reflected signal is received by the receiver. By doing this, the approach to the bridge and crane boom is detected.

  In the detection method described in Patent Document 2, two sets of ultrasonic sensors are attached to the base of the crane boom together with a transmitter and a receiver, a transmission signal is output from the transmitter, and a signal reflected from an obstacle is received by the receiver. It receives, detects the time difference between the transmission signal and the reception signal, performs a determination process, and detects the approach to the crane boom and surrounding buildings.

In the detection method described in Patent Document 3, a plurality of sets of ultrasonic sensors are attached to the tip of a crane boom together with a transmitter and a receiver, a transmission signal is output from the transmitter, and the reflected signal is received by the receiver. Then, by comparing the received signal with a preset reference value, the proximity of the electric wire, cable or other overhead wire is detected.
JP-A-11-278794 Japanese Patent Laid-Open No. 7-112893 JP-A-10-279283

  However, the methods described in Patent Literature 1 and Patent Literature 2 are intended for a wide shape such as a bridge or a wall of a building. For this reason, the level of the signal reflected on the object and received by the receiver also becomes high, and it is possible to detect the approach of the obstacle located far away and the crane. When a striate having a narrow shape is an object, there is a problem that it cannot be detected unless it is in the vicinity of the object.

  Moreover, although the method of patent document 3 is aimed at an aerial transmission line, since a crane approaches from not only one direction but a transmission line with respect to a transmission line, several sets of sensors are needed. When a plurality of sets of sensors are used, the signal level from the transmitter is lower than when a single set of sensors is used, and there is a problem that the detection distance is shortened.

  Moreover, in the detection method of patent document 1-patent document 3, since a sensor and a detection apparatus are attached to the boom tip or the base of a crane, in most cases, the apparatus is driven by a battery. There is a common problem that a signal having a large amplitude cannot be output from the transmitter. Moreover, in the detection method of patent document 1-patent document 3, in addition to the signal from a target object, sudden noise etc. may be detected and a malfunction may be produced.

  On the other hand, in each electric power company, the safe separation distance between the transmission line and the crane is determined at the work site of the crane working under the overhead transmission line (safe separation distance of 4 m in the transmission line with a voltage of 110 kV or less).

  Therefore, the object of the present invention is to provide a transmission line and a crane without reducing the detection distance even when a linear object having a long and narrow shape such as an overhead power transmission line is used as a detection object. Due to the proximity detection device that can sufficiently detect the detection target even at a safe separation distance, and that can output a signal having a larger amplitude than the power supply voltage from the transmitter and sudden noise, etc. when driven by a battery An object of the present invention is to provide an approach detection method capable of preventing malfunction.

  In order to achieve the above object, the proximity detection device of the present invention generates a pulse signal having amplitudes on the positive side and the negative side at regular time intervals, and generates a positive side signal and a negative side signal of the amplitude of the pulse signal. A transmitter for transmitting a transmission signal to the obstacle by separating and reversing the amplitude of the negative signal and adding it to the plus signal; and a reflection reflected by the transmission signal upon hitting the obstacle And a receiver for receiving a signal.

  The receiver amplifies the received reflected signal and then resonates at the center frequency of the transmission signal to extract the frequency component of the signal reflected by the obstacle from the received signal. be able to.

  The receiver may be connected to a wireless device that transmits a wireless signal when approaching the obstacle, and further provided with an alarm device that receives the wireless signal and issues an alarm when an abnormality occurs. it can.

  Further, the proximity detection device of the present invention is attached to the tip of the crane boom, a wireless device that transmits a wireless signal when approaching a proximity sensor and an obstacle provided with a transmitter and a receiver, and a wireless device from the wireless device when an abnormality occurs. An approach detection device having an alarm device for transmitting a signal by radio transmission and outputting an alarm, wherein the transmitter generates pulse signals having amplitudes on the plus side and the minus side at regular time intervals, and Transmitting a transmission signal whose output is increased by separating a positive-side signal and a negative-side signal of an amplitude, inverting the amplitude of the negative-side signal and adding the inverted signal to an obstacle, and receiving the receiver Is characterized in that the transmission signal receives a reflected signal reflected by the obstacle.

  The receiver amplifies the received reflected signal and then resonates at the center frequency of the transmission signal to extract the frequency component of the signal reflected by the obstacle from the received signal. be able to.

Furthermore, the approach detection method of the present invention transmits a transmission signal to an obstacle, receives a reception signal reflected by the obstacle, and an amplitude value of the reception signal exceeds a preset threshold value _Vth . And then detecting a time width in which the amplitude of the received signal continuously exceeds the threshold value, and the time width exceeds a preset threshold value T _th It is characterized by detecting the presence or absence of approach by determining whether or not.

  The proximity detection device of the present invention separates the positive signal and negative signal of the amplitude of the pulse signal, inverts the amplitude of the negative signal and adds it to the positive signal to increase the output. Since the signal is transmitted to the obstacle, even if the object to be detected is a long, narrow area or narrow shape such as an overhead power transmission line, the transmission line is not shortened. The detection object can be sufficiently detected even at a safe separation distance between the crane and the crane.

  In addition, after amplifying the received reflected signal, it resonates at the center frequency of the transmission signal, and by extracting the frequency component of the signal reflected by the obstacle from the received signal, the signal reflected from the obstacle It is possible to extract and amplify only the frequency component. Therefore, the signal-to-noise ratio can be improved by removing unnecessary signals other than the detection target such as a power transmission line, and the signal reflected from the detection target located far away can be stably detected. .

Furthermore, the approach detection method of the present invention not only determines whether or not the amplitude value of the received signal exceeds a preset threshold value _Vth , but further, the amplitude of the received signal continuously exceeds the threshold value. Since it is also determined whether or not the time width has exceeded a preset threshold value T _th , the waveform reflected from the detection target can be accurately captured, It is possible to reduce malfunctions due to sudden noise or the like.

  As described above, according to the approach detection device and approach detection method of the present invention, the approach to the crane is far away not only in a wide shape such as a bridge or a building wall but also in an overhead power transmission line. There is an effect that it can be easily detected even from the position. Moreover, it satisfies the condition of the safe separation distance (safety separation distance of 4 m in a transmission line with a voltage of 110 kV or less) determined by the electric power company, and can be applied to crane monitoring working under an overhead transmission line.

Moreover, since a commercially available open-type ultrasonic sensor can be used as the sensor, an inexpensive apparatus can be manufactured. In addition, when driven by a battery, a signal having a larger amplitude than the power supply voltage can be output from the transmitter, and the battery drive etc. is attached to the tip of the boom, etc., so that the constraint condition is satisfied. Configuration is possible.
Note that in the present invention, not only the above-described wire bodies such as the overhead power transmission line but also the overhead distribution line and the like can be the detection target.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic diagram showing the entire system of the approach detection device of the present embodiment. In this approach detection device 1, the sensor 10 provided with the transmitter 20 and the receiver 30 is attached to the tip of the boom of the crane, the signal emitted from the transmitter 20 is reflected by the power transmission line 5, and the receiver 30. It can be received at. A radio device 40 is connected to the receiver 30. When an abnormality is detected, the radio wave is transmitted to the alarm device 50 on the ground and an alarm can be output. Hereinafter, each configuration will be described in detail.

(Sensor 10)
There are two types of sensors: an open type structure and a drip-proof type structure. Usually, a sensor having a drip-proof type structure is used for outdoor use. On the other hand, when an open type ultrasonic sensor is used outdoors, since it is sensitive to rain and dust, it is necessary to take measures against drip and dust at construction sites.
In this embodiment, an ultrasonic sensor 11 having an open structure is used to increase transmission output and reception sensitivity. However, as shown in FIG. 2, a drip-proof net 13 (thin paper-like surface processed with a fluororesin) is used. Is attached to the opening of the ultrasonic sensor 11 to take measures against drip and dust. Further, when the drip-proof net 13 is replaced due to dirt or damage, the drip-proof net 13 is attached to the opening of the ultrasonic sensor 11 using a rubber O-ring 15 so that it can be easily replaced at the construction site. ing.
By using this ultrasonic sensor 11, if there is only one drip-proof net 13, there is a sufficient prevention effect if it is light rain without reducing the sensor output and reception sensitivity. In addition, a commercially available ultrasonic sensor 11 can be used, and the cost can be reduced.

(Transmitter 20)
In a transmitter, a circuit that generates a pulse signal at a constant time interval is conventionally used. In this case, the amplitude of a transmission signal output from a sensor is an amplitude equal to or lower than a power supply voltage (for example, a transmitter is connected). When driven by DC12V, the amplitude of the transmission signal is 12V at the maximum).
In the present embodiment, in order to output a transmission signal having an amplitude equal to or higher than the power supply voltage, the transmitter 20 includes an oscillation circuit 21, an amplification circuit 23, a separation circuit 25, an inverting circuit 27, and an addition circuit as shown in FIG. 29 and is transmitted from the sensor 10a. Hereinafter, each circuit will be briefly described.
(Oscillation circuit 21)
A pulse signal having a center frequency of the sensor (for example, around 40 kHz in the case of an ultrasonic sensor) is oscillated at regular intervals.
(Amplifier circuit 23)
The amplitude of the transmission signal transmitted by the transmission circuit 21 is amplified at a predetermined magnification. An example of the waveform at time A after being amplified by the amplifier circuit 23 is shown in FIG. In this example, a pulse having a center frequency of 40 kHz of the sensor at a power supply voltage of DC 12 V is output in a width of 1.8 ms and a transmission signal is output in a cycle of 36 ms (corresponding to a distance of 6 m).
(Separation circuit 25, inversion circuit 27, addition circuit 29)
As shown in FIG. 3B, the oscillation circuit 21 and the amplification circuit 23 output a pulse signal having a center frequency of the sensor at a constant cycle.
However, since the amplitude larger than the power supply voltage cannot be obtained only by these processes, the following method is used. First, the separation circuit 25 separates the transmission signal into a positive signal and a negative signal. Next, the inverting circuit 27 inverts the negative signal. Further, the adder circuit 29 adds the two separated signals again to output a transmission signal having an amplitude larger than the power supply voltage to the sensor.
As described above, in this embodiment, as post-processing of the transmission circuit, a circuit that separates the plus signal and minus signal of the amplitude of the transmission signal and inverts and adds the amplitude of the minus signal is added. Thus, it is possible to output a transmission signal having an amplitude greater than or equal to the power supply voltage, and it is possible for the transmission signal output from the transmitter 20 to reach a transmission line located far away.

(Receiver 30)
The signal received by the receiver includes a signal reflected from an obstacle such as a transmission line (a signal having the same frequency component as the center frequency of the sensor) and other noise signals. The reflected signal is attenuated when a transmission line located far away is targeted, and it is also assumed that the signal is substantially equivalent to the noise signal level. For this reason, the conventional receiver uses a circuit that amplifies the received signal from the sensor.
In the present embodiment, as shown in FIG. 4, in addition to the conventional amplifier circuit 31, a circuit that resonates at the center frequency of the sensor is incorporated in two stages to extract a necessary frequency component from the received signal. The ratio is improved.
Specifically, the receiver 30 includes an amplifier circuit 31, a resonance circuit 33, and a determination circuit 35.
(Amplifier circuit 31)
The amplitude of the received signal received by the sensor 10b is amplified by a predetermined magnification.
(Resonance circuit 33 (two stages))
By resonating the reception signal at the center frequency of the sensor, the frequency component of the reception signal reflected by the obstacle or the power transmission line is extracted from the reception signal and amplified. Here, the signal is resonated in two stages by being input to the preceding circuit and further resonating.
(Determination circuit 35)
The approach of an obstacle, a power transmission line, and a crane is determined by a determination processing method described later.
As described above, in this embodiment, after the entire received signal is amplified by the amplifier circuit, the circuit that resonates at the center frequency of the sensor is processed in two stages, so that the frequency component of the signal reflected from the obstacle such as the power transmission line is obtained. Remove and amplify.
Thereby, the signal-to-noise ratio can be improved by removing unnecessary signals other than the power transmission line, and the signal reflected from the power transmission line located far away can be stably detected. Further, by using the resonance circuit to resonate the signal in two stages, that is, by inputting the signal to the preceding circuit and further resonating, a further noise removal effect can be obtained.

(Determination process)
Conventionally, as a method of detecting an approach of an obstacle such as a power transmission line and a crane from a received signal, a method of detecting an abnormality by performing an over-threshold determination of the amplitude of the received signal has been used.
In the present embodiment, in addition to the determination that the amplitude exceeds the threshold value, the time width in which the amplitude of the received signal continuously exceeds the threshold value is detected, and the threshold value excess determination is also performed for that time width. An abnormality is detected. As a result, measures against sudden noise and noise are taken.
Specifically, as shown in FIG. 5, the approach of an obstacle such as a power transmission line and a crane is determined by three processes of receiving signal extraction 36, amplitude threshold value determination 37, and time width threshold value determination 38. ing.
(Cut out received signal 36)
The waveform of the received signal (for one cycle) is cut out by the time width Tm. The time range corresponding to the detection distance is set as the extraction range.
(Amplitude threshold judgment 37)
First, it is determined whether or not a threshold value V _th having a predetermined amplitude is exceeded for a waveform cut by Tm (FIG. 6).
(Time width threshold judgment 38)
Next, the amplitude of the received signal detects a duration exceeding continuously threshold V _th, if exceeded continuously for the predetermined threshold value T _th or more, the abnormality detection (Figure 6).
As a result, it is possible to accurately capture the waveform reflected from the transmission line, and to reduce malfunctions due to sudden noise, etc., compared to the case where an abnormality is detected only by determining whether the amplitude exceeds the threshold value. Become.

  7 and 8 show an actual application example of the proximity detection device of the present embodiment. An approach detection device 1 having a sensor 10 (consisting of nine ultrasonic sensors) provided with a transmitter 20 and a receiver 30 is attached to the tip of the boom 7 of the mobile crane 3. Assuming that the boom 7 approaches the power transmission line 5 from all directions, the nine sensors are arranged in different directions so as not to form a blind spot. A radio device 40 is connected to the receiver 30, and when an abnormality is detected, it is wirelessly transmitted to a ground alarm device 50 and an alarm is output by a patrol light 60.

  According to this apparatus, even when the transmission line 5 located in the distance is targeted, there is an effect of detecting the approach of the transmission line 5 and the boom 7 of the crane. It has been confirmed that the sensor can be detected up to a separation distance of 4 m. Satisfies the safety separation condition (safety separation distance of 4 m in a transmission line with a voltage of 110 kV or less) determined by the electric power company, and can be applied to crane monitoring working under an overhead transmission line.

  In addition, the proximity detection device of the present embodiment improves the detection capability of the ultrasonic sensor as compared with the prior art. Therefore, an intruder / intrusion vehicle that conventionally used an ITV camera or an infrared sensor and could not use the ultrasonic sensor. The present invention can also be applied to a detection device. In addition, since the detection capability is improved, the present invention can be applied to a crane approach monitoring device for bridges, pile driving, collision between cranes, and the like.

  In this embodiment, an ultrasonic sensor is used as a sensor. However, it is needless to say that the present invention can be applied to an apparatus that transmits a pulse signal such as a sound wave sensor or a laser and receives the reflection.

It is a schematic diagram which shows the whole system of the proximity detection apparatus of this embodiment. It is a perspective view which shows an example of the sensor used for the proximity detection apparatus of this embodiment. It is a block diagram which shows an example of the transmitter used for the proximity detection apparatus of this embodiment. It is a figure which shows the transmission waveform in the middle stage in the transmitter of FIGS. It is a block diagram which shows an example of the receiver used for the proximity detection apparatus of this embodiment. FIG. 5 is a block diagram illustrating an example of a determination circuit in the receiver illustrated in FIG. 4. It is a figure explaining the approach determination method of this embodiment. It is the schematic which applied the approach detection apparatus of this embodiment to the detection of a power transmission line. It is a schematic diagram which shows the structural example of the approach detection apparatus of this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Approach detection apparatus 3 Mobile crane 5 Transmission line 7 Boom 10 Sensor 11 Ultrasonic sensor 13 Drip-proof net 15 Rubber O-ring 20 Transmitter 21 Oscillator circuit 23 Amplifier circuit 25 Separation circuit 27 Inversion circuit 29 Addition circuit 30 Receiver 31 Amplification circuit 33 Resonance circuit 35 Determination circuit 36 Extraction of received signal 37 Amplitude threshold determination 38 Time threshold determination 40 Wireless device 50 Alarm device

Claims (6)

A pulse signal having an amplitude on the plus side and the minus side is generated at a certain time interval, the plus side signal and the minus side signal of the amplitude of the pulse signal are separated, and the amplitude of the minus side signal is inverted to be plus The transmitter for transmitting a transmission signal whose output is increased by adding to a side signal to an obstacle; and
The receiver for receiving the reflected signal reflected by the transmission signal hitting the obstacle;
An approach detection device comprising a sensor provided with a sensor.   The receiver amplifies the received reflected signal and then resonates at a center frequency of the transmission signal to extract a frequency component of the signal reflected by an obstacle from the received signal. The approach detection device according to claim 1.   The receiver is connected to a wireless device that transmits a wireless signal when approaching the obstacle, and further includes an alarm device that receives the wireless signal and issues an alarm when an abnormality occurs. The approach detection apparatus according to 1. A wireless device that is attached to the tip of the crane boom and is provided with a transmitter and a receiver, and a wireless device that transmits a wireless signal when approaching an obstacle, and an alarm that outputs a wireless signal when the abnormality occurs and outputs an alarm in the event of an abnormality A proximity detection device having a device,
The transmitter generates a pulse signal having an amplitude on the plus side and the minus side at a constant time interval, separates the plus side signal and the minus side signal of the amplitude of the pulse signal, and the amplitude of the minus side signal. Is transmitted to the obstacle to increase the output by adding to the plus side signal by inverting
The proximity detector according to claim 1, wherein the receiver receives a reflected signal reflected by the transmission signal hitting the obstacle.   The receiver amplifies the received reflected signal and then resonates at a center frequency of the transmission signal to extract a frequency component of the signal reflected by an obstacle from the received signal. The approach detection device according to claim 4. After transmitting the transmission signal to the obstacle, receiving the reception signal reflected by the obstacle and determining whether the amplitude value of the reception signal exceeds a preset threshold value V _th , By detecting a time width in which the amplitude of the received signal continuously exceeds the threshold value, and determining whether the time width exceeds a preset threshold value T _th An approach detection method characterized by detecting the presence or absence of an object.

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