JP3031777B2 - Work alarm - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[Industrial applications] The master station is mounted on a power shovel for construction work, the slave station is mounted on a worker's helmet, etc., and ultrasonic signals are transmitted and received between the master station and the slave station. The present invention relates to an alarm device for providing warning information to both stations when a slave station exists within a predetermined distance from the stations, and for ensuring the safety of workers during work.

[0002]

2. Description of the Related Art A conventional work alarm will be described with reference to FIG.

[0003] The master station CPU 9 in the master station apparatus 15 drives the drive circuit 14, and the master station ultrasonic transmitter 7 emits an ultrasonic wave of frequency f 0. Further, the transmission is performed by the CPU 9.
The time measurement timer 10 is turned on at the same time as the transmission.

When the slave station device 6 approaches the master station device 15 and enters the ultrasonic receiving area, the slave station ultrasonic transceiver 1
(In FIG. 2, four are provided) detect the ultrasonic waves,
When the detection level exceeds the comparator 2, the slave station side C
The PU 3 activates the slave station side warning device 4 to call attention to the slave station carrier.

At this time, the slave-station-side CPU 3 drives the drive circuit 5 so that it differs from the master-station ultrasonic transmission frequency f0.
An ultrasonic wave having a transmission frequency of 1 is transmitted from the slave station ultrasonic transceiver 1 to the master station ultrasonic receiver 8.

The reception level received by the master station ultrasonic receiver 8 is compared by a comparator 11 having a threshold value set in advance by a threshold value setting circuit 12, and the reception level exceeding the threshold value is received. When signal is present, time measurement timer 1
Turn 6 off.

[0007] The master station CPU 9 reads the value of the time measurement timer 10, calculates the distance between the master station device 15 and the slave station device 6 from the time required for transmission and reception and the speed of the ultrasonic wave, and calculates the calculated value. For example, if the distance is smaller than a preset distance, it is determined that there is a danger and the master station warning means 13 is driven.

In such a device, for example, the master station device 15 is mounted on a power shovel, and the slave station device 6 is mounted on a helmet worn by an operator to draw attention to the operator and the driver of the power shovel, To improve safety.

[0009]

According to the prior art described above, when the master station device 15 receives a reception signal exceeding a preset threshold value, it receives the reception signal from the slave station. And the warning means is activated.

Therefore, even if external noise is input,
If the threshold value is exceeded, a false alarm is frequently generated because the threshold value is treated as a received signal. Generally, the carrier frequency of the transmitted and received ultrasonic waves is 20 to 30 (KHz), but there is also a fact that many ultrasonic waves generated by caterpillars and the like of a construction power shovel belong to frequencies in this band. .

[0011] When erroneous warnings occur frequently, the reliability of the warnings is reduced, and the commercial value of the apparatus is reduced.

[0012] Further, the operation may be stopped every time a warning is issued, resulting in a situation in which the working efficiency is significantly reduced.

[0013]

The following are conceivable means for carrying out the present invention.

The master station comprises a master station and at least one slave station, wherein the master station transmits ultrasonic waves of a certain frequency, receives ultrasonic waves of a frequency different from the transmission frequency, and Means for analyzing the frequency component of the wave, means for calculating the error between the first experimental value set in advance and the power spectrum of the received wave, and the fundamental frequency of the transmitted wave of the slave station in the frequency component of the received wave. Means for determining whether or not the signal is included; means for measuring the time from transmission to reception; and the square root of the sum of the square of the difference between the power spectrum of the received wave and the first experimental value, Means for judging a dangerous state from the measurement time from transmission to reception only when the power spectrum of the received wave has a different frequency component to be received by the receiving means, When it is determined that The slave station further comprises: a means for receiving a transmission signal from the master station; a means for transmitting an ultrasonic wave having a frequency different from the transmission frequency of the master station; A configuration is conceivable which comprises means for issuing a warning when the reception level is equal to or higher than a preset threshold value.

It is also conceivable that the means for analyzing the frequency component of the received wave has a threshold setting means.

Further, when there are a plurality of slave stations, it is recognized which slave station frequently intrudes into the danger area, and before starting the work, the worker is given particular safety guidance in advance, and the accident during the work is performed. In order to prevent such a situation, it is conceivable to provide a means for transmitting a different transmission frequency for each slave station, and the master station also has a receiving means corresponding to the frequency.

Note that a configuration in which the transmitting / receiving means in the master station is arranged in at least two directions is also conceivable. Of course, the configuration is not limited to two directions, and for example, a configuration in which the components are arranged in four directions can be considered.

Further, the following means may be used to distinguish between a signal and noise. A master station, comprising at least one slave station, wherein the master station transmits ultrasound, means for receiving an encoded ultrasound signal, and means for calculating a correlation function of the received signal, A means for measuring the time from transmission to reception of the encoded ultrasonic signal, and a measurement from transmission to reception only when the result of calculation by the means for calculating the correlation function is greater than or equal to a preset threshold. Means for judging a dangerous state from time, and means for giving a warning when it is judged to be dangerous, further comprising: a means for receiving a transmission signal from a master station; and a reception level of a transmission signal from the master station. Is a means for issuing a warning when is equal to or larger than a preset threshold value, and a means for transmitting an encoded ultrasonic signal.

[0019]

According to the present invention, for example, a master station is mounted on a work excavator, and a slave station is mounted on a helmet worn by an operator, thereby calling attention to the worker and the driver of the excavator.
This is a device that improves the safety of work.

First, the master station drives a drive circuit for a transmission wave, and a transmitter provided in the master station emits an ultrasonic wave of a certain frequency (for example, f0).

At the same time as the transmission, the time measurement timer is turned on.

When the slave station approaches the master station and enters the ultrasound reception area, the ultrasound transceiver of the slave station (usually provided in plurality in consideration of directivity) detects the ultrasound. When the detection level exceeds a certain threshold value, the slave station activates an alarm device in the slave station to call attention to a slave station carrier.

At the same time, the slave station drives the transmission wave driving circuit, and sends an ultrasonic wave having a transmission frequency f1 different from f0 from the ultrasonic transceiver in the slave station to the ultrasonic receiver in the master station. Send to.

The signal received by the ultrasonic receiver of the master station is subjected to frequency analysis by FFT or the like, and its power spectrum is obtained.

An error calculation is performed between the value of the power spectrum and a first experimental value set in advance by experiments or the like, and the calculated result is within a second experimental value set in advance by experiments or the like. If the received signal includes the fundamental frequency f1 of the slave station, the received signal is determined not to be external noise but a transmission signal from the slave station, and the time measurement timer is turned off.

The master station reads the value of the time measurement timer, calculates the distance between the master station and the slave station from the time taken for transmission and reception and the speed of the ultrasonic wave, and calculates the calculated value, for example, in advance. If the distance is smaller than the distance, it is determined to be in a dangerous state, and the master station warning means is driven.

For example, a warning is issued in the master station.

According to the present invention, an external noise and a received signal can be reliably distinguished, and a highly reliable apparatus free from false alarms can be provided.

The signal processing in the master station by the present apparatus may not be performed on all received signals, but may be performed only on received signals exceeding a certain threshold to speed up the signal processing. .

Further, when there are a plurality of slave stations (operators), the transmission frequency of the ultrasonic waves of the slave stations is different for each slave station, and the receiver corresponding to this is also provided on the master station side. By doing so, it is possible to recognize which slave station frequently enters the danger area, and to give the worker special safety guidance in advance before starting work, thereby further preventing accidents during work. Becomes

In addition, the master station arranges receivers corresponding to the transmission frequency of the slave station in, for example, four directions, thereby recognizing which direction and which slave station has entered the dangerous area. Thus, the driver of the vehicle equipped with the master station device can quickly avoid danger.

The above description uses the signal processing based on the received power spectrum. Hereinafter, a method of distinguishing between a signal using a coded signal and noise will be described.

First, the master station drives a transmission wave driving circuit, and an ultrasonic wave of a certain frequency (for example, f0) is transmitted from a transmitter provided in the master station.

At the same time as the transmission, the time measurement timer is turned on.

When the slave station approaches the master station and enters the ultrasound reception area, the ultrasound transceiver of the slave station (usually provided in plurality in consideration of directivity) detects the ultrasound. When the detection level exceeds a certain threshold value, the slave station activates an alarm device in the slave station to call attention to a slave station carrier.

At the same time, the slave station operates the code generation circuit 30.
The transmitter transmits the encoded transmission wave by driving the driving circuit, and transmits the ultrasonic wave of the encoded transmission frequency from the ultrasonic transceiver in the slave station to the ultrasonic receiver in the master station.

Here, as an example of encoding, there is, for example, an M-sequence.

For the signal received by the ultrasonic receiver of the master station, a correlation function value is obtained by calculating a correlation function.

If the calculated value of the correlation function is equal to or higher than a reference level set in advance through experiments or the like, the received signal is determined not to be external noise but to be a transmission signal from a slave station, and the time measurement timer is turned off.

The master station reads the value of the time measurement timer, calculates the distance between the master station and the slave station from the time taken for transmission and reception and the speed of the ultrasonic wave, and the calculated value is, for example, set in advance. If the distance is smaller than the distance, it is determined to be in a dangerous state, and the master station warning means is driven.

As a driving method of the master station warning means, for example, an alarm may be issued in the master station.

According to the present invention, it is possible to reliably distinguish external noise from a received signal and to provide a highly reliable apparatus free from false alarms.

[0043]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS.

This embodiment is configured to include the slave station device 6 and the master station device A19.

Generally, a plurality of slave station devices 6 are used at the same time.

The slave station device 6 includes a slave ultrasound transmitter / receiver 1, a comparator 2, a slave CPU 3, a slave warning means 4, and a drive circuit 5.

The local station ultrasonic transmitter / receiver 1 is a means for transmitting / receiving ultrasonic waves from the local station. Usually, a plurality of the local station ultrasonic transmitters / receivers are provided in one station and are constituted by a piezoelectric element such as ceramic.

The comparator 2 comprises a slave station ultrasonic transceiver 1
Is a means for judging whether or not the reception level of the transmission signal from the master station received by the master station is equal to or higher than a predetermined value, and is constituted by an electronic device such as an operational amplifier.

When the output level of the comparator 2 is equal to or higher than the predetermined value, the slave station CPU 3 determines that a warning should be given,
This is a means for driving the slave station side warning means 4 and is constituted by an electronic device such as a semiconductor microprocessor.

The slave station side warning means 4 is a means for giving a warning for notifying the slave station carrier of the danger situation, and is constituted by an LED, a chime or the like.

The driving circuit 5 is means for driving the slave station ultrasonic transceiver 1 in order for the slave station device 6 to transmit an ultrasonic wave in response to a transmission signal from the master station. It is composed of an electronic device such as TTL.

The master station apparatus A19 includes a master station ultrasonic transmitter 7,
Master station ultrasonic receiver 8, A / D converter 16, signal processing DS
P17, drive circuit 14, RAM 18, master station warning means 1
3. It has a time measurement timer 10.

Master station ultrasonic transmitter 7, Master station ultrasonic receiver 8
Are means for transmitting ultrasonic waves from the master station, and means for receiving the ultrasonic signals transmitted by the slave station device 6 in response to the transmission of the ultrasonic waves from the master station. It is configured using. Note that a plurality of master station ultrasonic transmitters 7 and master station ultrasonic receivers 8 may be provided in consideration of the directional characteristics of ultrasonic signals.

The A / D converter 16 includes the master station ultrasonic receiver 8
Is a means for performing analog-to-digital conversion of the signal received by the electronic device, and is configured by an electronic device such as a resistor or TTL.

The time measurement timer 10 transmits the ultrasonic wave transmitted by the slave station device 6 in response to the transmission signal after the master station device A transmits the ultrasonic wave by the master station ultrasonic transmitter 7. Signal processing DS via master station ultrasonic receiver 8 and A / D converter 16
This is a means for measuring the time until reception by P17, and is configured by electronic devices such as a clock circuit using various TTLs, a frequency divider, and a resistor.

The signal processing DSP 17 converts the received signal into a RAM.
18, the time measurement timer 10 is turned off, the received signal is subjected to FFT conversion, a power spectrum is obtained, a predetermined operation is performed, and it is determined whether or not the received signal is noise. If it is determined that the signal is a signal, the distance to the slave station device 6 is calculated from the time measured by the time measurement timer 10 and the speed of the ultrasonic wave. 13 and is configured using a semiconductor digital signal processor (hereinafter referred to as "DSP").

The signal processing DSP 17 contains a ROM in which an arithmetic processing program and the like are stored in a ROM.

The drive circuit 14 is means for driving the master station ultrasonic transmitter 7 in order to transmit ultrasonic waves from the master station apparatus A, and is composed of electronic devices such as transistors and TTL.

The RAM 18 is a means for storing the results of all operations performed by the signal processing DSP 17, and is constituted by a semiconductor memory or the like.

The master station warning means 13 is a signal processing DSP 17
Means for warning a person wearing the master station apparatus A19 of a danger state by the drive signal from
It is composed of ED, chime, etc.

The operation of the first embodiment will be described with reference to FIGS.

Based on the drive signal from the signal processing DSP 17, the drive circuit 14 sends a trigger signal to the master station ultrasonic transmitter 7.

The master station ultrasonic transmitter 7 transmits an ultrasonic wave having a frequency f0 (see FIG. 3A). The transmission signal is
The received signal is received by the slave station ultrasonic transceiver 1 (see FIG. 3B).

The reception level of the reception signal is compared with a certain threshold value by the comparator 2, and when the reception level is lower than the threshold value, the state is maintained.

At this time, a fixed period T
(For example, at 150 (msec)), ultrasonic waves are being transmitted one after another.

When the reception level of the received signal is higher than the threshold value, the slave station CPU 3 drives the slave warning means 4 to give a warning to the person carrying the slave station device 6.

As a warning method, any means may be used as long as it is a means for prompting a warning such as a light emission by an LED or a chime.

By the way, when the level of the received signal is higher than a predetermined threshold value, the slave station CPU 3 drives the drive circuit 5 simultaneously with the drive of the slave station warning means 4, and An ultrasonic wave is transmitted by the sound wave transceiver 1.

The transmission of the ultrasonic waves is performed to the master station A19, and the carrier frequency thereof is different (f1) from the transmission signal of the master station (see FIG. 3 (c)).

The transmission signal from the slave station device 6 is received by the master station ultrasonic receiver 8, and the time measurement by the time measurement timer 10 is stopped (see FIG. 3D).

The master station device A 1
The time Δt from transmission to reception of the ultrasonic wave No. 9 will be measured.

When the received signal is a signal from the slave station device 6, R = (C × Δt) / 2 (Equation 1) where R is the master station device A19 and the slave station device 6. Distance to C
Is the speed of the ultrasonic wave.) The distance between the master station device A19 and the slave station device 6 is determined, and RA
It is stored in M12. When the distance is equal to or less than the predetermined value, the signal processing DSP 17 sends a signal to the master station warning unit 13,
A warning is given to a person equipped with the master station device A19.

As a warning method, any means such as light emission by LED, chime warning, etc. may be used.

Further, regardless of the output of the warning, the period T
(For example, 150 (msec)), a new master station A
The transmission of the ultrasonic wave from the computer starts (see FIG. 3E).

By the way, if the received signal is truly a transmission signal from the slave station device 6, the above-mentioned processing may be performed.
An erroneous warning due to extraneous noise is generated, and the reliability of the device is reduced.

Therefore, the received signal from the outside is represented by A /
After conversion into a digital signal by the D converter 16, it is determined whether or not the signal is external noise.

Hereinafter, description will be made with reference to FIG.

First, a plurality of received signal data (Xn) are accumulated, and the average (XA), the variance (σx)
Is calculated, and normalization processing is performed to make the distribution of the received data a normal distribution, thereby obtaining normalized processing data X (n) (step 100).

Next, FFT processing of the normalized data is performed.

To perform the FFT processing, first, a WINDOW
Processing is performed (step 110).

The frequency analysis by FFT is different from the Fourier transform in that only a certain time is extracted from the signals existing on the infinite time axis.

At this time, it is necessary to multiply by a weight function called a WINDOW function (also referred to as a window function) in order to avoid the influence of taking out for a certain amount of time.
This is called a WINDOW process.

The window functions include a rectangular window, a Hamming window,
There are various window functions such as a Gaussian window. Here, a Hamming window, which is generally used, is used.

The Hamming window function W (n) is generally expressed by the following equation (2).
Given by

W (n) = 0.54−0.46 cos (2πn / (N−1)) (Equation 2) (where 0 ≦ n ≦ N−1, where N is the number of sampling data) ) Multiplied by the window function W (n) X (n) ×
W (n) is newly set to X (n).

Next, an FFT process is actually performed to obtain an amplitude spectrum as its magnitude.

The result of the FFT processing of X (n) is obtained by the following equation 3 as follows.

X (k) = ΣX (n) exp (−j2πnk / N) (Equation 3) (where, Σ is a sum of n from n = 0 to N−1, and j is an imaginary unit) , And exp represents an exponential function.) Further, the amplitude spectrum, | X (k) |, is obtained by obtaining the absolute value of X (k) (step 120).

Next, at step 130, the power spectrum Xi is obtained.

The power spectrum Xi is determined by the square of the amplitude spectrum | X (k) |. Next, in step 140, Euclidean distance calculation is performed.

In this calculation, a pre-processing for determining an error d between the first experimental value Yi and the power spectrum Xi, which has been set in advance through experiments, simulations, and the like, and discriminating the received signal from external noise. Perform the operation.

The error d is obtained by the following equation (4).

D = SQR (Σ (Xi−Yi) ² ) (Equation 4) (where, Σ represents the sum of i from i = 1 to N, and SQR represents a function for obtaining the square root) In step 150, the above d is compared with a threshold level S, which is a second experimental value set in advance by experiments, simulations, and the like.

If d is larger than S, it is determined that the noise is external.

If d is less than or equal to S, there is a high possibility of a transmission signal from the slave station, and the process branches to step 160.

In step 160, the frequency component of d is
It is determined whether or not the transmission frequency component f1 of the slave station exists.

If the noise does not exist, it is determined that the noise is external.

If there is, it is determined that the signal is a transmission signal from a slave station.

By the above series of processing, it is possible to accurately distinguish whether a received signal is an external noise or a transmission signal from a slave station.

When the above-described apparatus is used at a construction site, for example, a method of mounting the master station apparatus A19 on a work excavator and mounting the slave station apparatus 6 on a worker's helmet may be considered.

According to the present invention, various types of external noise generated during construction and signals from slave stations can be accurately identified, and the driver of a power shovel equipped with a master station pays attention to warnings. Work while improving the work efficiency,
Safety can be improved.

Next, a second embodiment of the present invention will be described with reference to FIG.

This embodiment is configured to include the slave station device 6 and the master station device B20.

In general, a plurality of slave station devices 6 are used at the same time.

The slave station device 6 comprises a slave ultrasound transmitter / receiver 1, a comparator 2, a slave CPU 3, a slave warning means 4 and a drive circuit 5, and is the same as that of the first embodiment. Since it can be used, detailed description of the components will be omitted.

The master station device B20 is connected to the master station ultrasonic transmitter 7,
Master station ultrasonic receiver 8, A / D converter 16, signal processing DS
P17, drive circuit 14, RAM 18, master station warning means 1
3. It has a time measurement timer 10 and a threshold value setting unit 27.

The master station ultrasonic transmitter 7, the master station ultrasonic receiver 8, the A / D converter 16, the signal processing DSP 17, the drive circuit 14, the RAM 18, the master station warning means 13, and the time measurement timer 10 Since the same components as those in the embodiment are used, the detailed description is omitted here.

The threshold value setting section 27 detects the level of the received signal after the A / D conversion by the signal processing DSP 17 and sets a threshold value in accordance with the detected level. Is a means for inputting only a signal exceeding the threshold value to the A / D converter 16, and is configured by electronic devices such as an operational amplifier, a resistor, and a power supply.

According to the present invention, not all the received signals are subjected to the FFT processing described in the first embodiment, but only the received signals exceeding the threshold level set according to the level of the received signal. Is subjected to FFT processing to increase the speed of signal processing.

The signal received by the master station ultrasonic receiver 8 is converted from analog to digital by the A / D converter 16 and sent to the signal processing DSP 17.

At the start of the apparatus, the master station continues transmission for a predetermined period of time (for example, one minute) at a constant period, accumulates reception level data in the RAM 18, and calculates an average value of the data by the signal processing DSP 17. And, for example, 70% of the average
Is adopted as a threshold, and the signal processing DSP 17 automatically changes the threshold set by the threshold setting unit 27.

Further, the threshold value is obtained by, for example, moving the slave station device 6 away from the master station device B20 by a predetermined distance before the work, and experimentally determining the reception level (for example, the A / D converter 1).
6 may be observed with an oscilloscope or the like), and only the transmission signal from the slave station device 6 may be compared and manually set to an approximate value.

After the received signal is input to the A / D converter 16, a series of processing is performed according to the flowchart shown in FIG. 4 to determine whether the noise is an external noise. Is exactly the same as in the first embodiment, and the description is omitted here.

According to the present embodiment, it is possible to provide an apparatus capable of processing received signals at higher speed.

Next, a third embodiment of the present invention will be described with reference to FIG.

This embodiment is an embodiment in the case where there are a plurality of slave stations. In order to simplify the explanation, the number of slave stations is two (the first slave station device 24 and the second slave station device 25). . 2
It may be more than a station.

The master station device C21 is connected to the master station ultrasonic transmitter 7,
f1 receiver 22, f2 receiver 23, A / D converter 1
6A, an A / D converter 16B, a signal processing DSP 17, a drive circuit 14, a RAM 18, a master station warning unit 13, a time measurement timer 10A, a time measurement timer 10B, and a display device 26.

Master station ultrasonic transmitter 7, A / D converter 16
A, A / D converter 16B, signal processing DSP 17, drive circuit 14, RAM 18, master station warning means 13, time measurement timer 10A, and time measurement timer 10B use the same ones as in the first embodiment. A detailed description of these will be omitted.

The f1 receiver 22 is a means for receiving the transmission signal (frequency f1) from the first slave station device 24.

[0120] The f2 receiver 23 is means for receiving a transmission signal (frequency f2) from the second slave station device 25.

The display device 26 is a device for displaying the number of times the slave station has entered the dangerous area, and is composed of a CRT, a liquid crystal display and the like.

The A / D converter 16A, A / D converter 16B, time measuring timer 10A, and time measuring timer 10B
Are provided corresponding to the number of slave stations.

Each of the first and second slave stations 24 and 25 has a slave ultrasound transmitter / receiver 1, a comparator 2, a slave CPU 3, a slave warning means 4, and a drive circuit 5. Is done.

Since these components are the same as those in the first embodiment, description thereof will be omitted.

However, it is built in the first child station device 24.
The transmission frequency of the slave ultrasonic transmitter / receiver 1 is f1, and the transmission frequency of the slave ultrasonic transmitter / receiver 1 incorporated in the second slave station device 25 is f2, and f1 and f2 are different.

It is to be noted that the transmission frequency of the slave station can be changed by changing the applied voltage of the ceramic which is a piezoelectric element.

The exchange of transmission / reception waves between the slave station and the master station and the signal processing after the master station receives the transmission wave from the slave station are almost the same as those in the first embodiment, but will be briefly described.

In response to the transmission signal (frequency f0) from the master station device C21, the first slave station device 24 transmits an ultrasonic wave having the frequency f1 to the master station device C21 and receives it at the f1 receiver 22. Is done.

The master station device C21 measures the time taken to transmit and receive the ultrasonic wave by the time measuring timer 10A, determines whether or not the slave station exists in the danger area, and gives a master station warning means in danger. 13 warns me.

At this time, the signal processing DSP 17 stores the number of warnings in the RAM 18 and displays
In FIG. 6, the number of warnings by the first child station device 24 is displayed.

As a display method, a method of simply displaying the number of warnings for each slave station, a method of displaying the number of warnings for each slave station as a cumulative frequency distribution graph, and the like can be considered.

After the operation, a printer for printing out the number of warnings for each slave station may be connected to the signal processing DSP 17 via an interface.

In this case, the signal processing DSP 17
The data stored in the storage unit 18 is called, and the data is transmitted to the printer.

The same operation is performed between the master station device C21 and the second slave station device 25 using the ultrasonic wave of the frequency f2 transmitted from the second slave station device 25.

According to the present embodiment, it is possible to grasp which slave station frequently enters the dangerous area, and to sufficiently explain the safety of the slave station before the work to the person carrying the slave station. Thus, it is possible to provide a work warning device that ensures the safety of the worker.

Further, as shown in FIG. 7 (slave station not shown), for example, the f1 receivers 22, f
By providing four receivers for two in four directions, the master station device D28 can determine in which direction and which slave station has entered the dangerous area.

That is, the signal processing DSP 17 performs A / D
The converted signal level is detected, and the direction from which the transmission signal is transmitted is detected.

[0138] This result can also be displayed on the display device 26.

As described above, by arranging the transmitter and the receiver of the slave station in a predetermined direction, the existence direction of the slave station can be recognized, and the driver of the power shovel equipped with the master station device D28 can It is possible to quickly avoid danger.

As shown in FIG. 11, the slave station may be provided with an ultrasonic wave transmitting / receiving section in four directions, and may receive a transmission signal from the master station without fail.

Next, an invention for distinguishing between a signal and noise by using a correlation function operation of an encoded ultrasonic transmission signal will be described with reference to the drawings.

FIG. 8 shows an embodiment of the present invention.

This embodiment is configured to include the slave station device 6 and the master station device E29.

Generally, a plurality of slave station devices 6 are used at the same time.

The slave station device 6 comprises a slave ultrasound transmitter / receiver 1, a comparator 2, a slave CPU 3, a slave warning means 4, a drive circuit 5, and a code generation circuit 30.

[0146] The slave station ultrasonic transceiver 1 is a means for transmitting and receiving ultrasonic waves from the slave station. A plurality of the slave station ultrasound transceivers are usually provided in one station, and are composed of a piezoelectric element such as ceramic.

The comparator 2 is composed of the slave station ultrasonic transceiver 1
Is a means for judging whether or not the reception level of the transmission signal from the master station received by the master station is equal to or higher than a predetermined value, and is constituted by an electronic device such as an operational amplifier.

If the output level of the comparator 2 is equal to or higher than the predetermined value, the slave station CPU 3 determines that a warning should be issued.
This is a means for driving the slave station side warning means 4 and is constituted by an electronic device such as a semiconductor microprocessor.

The slave station side warning means 4 is a means for giving a warning for informing the slave station carrier of a danger situation, and is composed of an LED, a chime or the like.

The code generation circuit 30 is means for encoding the ultrasonic signal in order to transmit the encoded ultrasonic signal in response to the reception of the transmission signal from the master station device E29.
It is composed of electronic devices such as PUs and various TTLs.

The drive circuit 5 is means for driving the slave station ultrasonic transceiver 1 so that the slave station device 6 transmits an encoded ultrasonic signal. The drive circuit 5 includes an electronic device such as a transistor or TTL. Be composed.

The master station device E29 includes the master station ultrasonic transmitter 7,
Master station ultrasonic receiver 8, A / D converter 16, signal processing DS
P17, drive circuit 14, RAM 18, master station warning means 1
3. It has a time measurement timer 10.

Master station ultrasonic transmitter 7, Master station ultrasonic receiver 8
Are means for transmitting ultrasonic waves from the master station, and means for receiving the ultrasonic signals transmitted by the slave station device 6 in response to the transmission of the ultrasonic waves from the master station. It is configured using. Note that a plurality of master station ultrasonic transmitters 7 and master station ultrasonic receivers 8 may be provided in consideration of the directional characteristics of ultrasonic signals.

The A / D converter 16 includes the master station ultrasonic receiver 8
Is a means for performing analog-to-digital conversion of the signal received by the electronic device, and is configured by an electronic device such as a resistor or TTL.

The time measurement timer 10 determines that the slave station device 6 transmits the ultrasonic wave transmitted by the slave station device 6 in response to the transmission signal after the master station device A transmits the ultrasonic wave with the master station ultrasonic transmitter 7. Signal processing DS via master station ultrasonic receiver 8 and A / D converter 16
This is a means for measuring the time until reception by P17, and is configured by electronic devices such as a clock circuit using various TTLs, a frequency divider, and a resistor.

[0156] The signal processing DSP 17 converts the received signal into a RAM.
18 and temporarily turn off the time measurement timer 10 and perform a correlation function operation on the encoded received signal.
Determine whether the received signal is a signal or noise,
When it is determined that the signal is from the slave station device 6, the distance to the slave station device 6 is calculated from the time measured by the time measurement timer 10 and the speed of the ultrasonic wave, and the distance is equal to or less than a predetermined value. At this time, it is a means for judging a “dangerous state” and driving the master station warning means 13 and is configured using a semiconductor digital signal processor (hereinafter referred to as “DSP”) or the like.

The signal processing DSP 17 contains a ROM in which an arithmetic processing program and the like are stored.

The drive circuit 14 is means for driving the master station ultrasonic transmitter 7 to transmit ultrasonic waves from the master station apparatus A, and is composed of electronic devices such as transistors and TTL.

The RAM 18 is a means for storing the results of all the operations performed by the signal processing DSP 17, and is constituted by a semiconductor memory or the like.

The master station warning means 13 is a signal processing DSP 17
Means for alerting a person wearing the master station device E29 of a danger condition by the drive signal from
It is composed of ED, chime, etc.

The operation of this embodiment will be described with reference to FIGS.

Based on the drive signal from the signal processing DSP 17, the drive circuit 14 sends a trigger signal to the master station ultrasonic transmitter 7.

The master station ultrasonic transmitter 7 transmits an ultrasonic wave having a frequency f0 (see FIG. 9A). The transmission signal is
The received signal is received by the slave station ultrasonic transceiver 1 (see FIG. 9B).

The reception level of the reception signal is compared with a predetermined threshold value by comparator 2, and when the reception level is lower than the threshold value, the state is maintained.

At this time, the master station A sends a fixed cycle T
(For example, at 150 (msec)), ultrasonic waves are being transmitted one after another.

When the reception level of the received signal is larger than the threshold value, the slave station side CPU 3 drives the slave station side warning means 4 to give a warning to the person carrying the slave station device 6.

As a warning method, any means may be used as long as it is a means for prompting a warning, such as light emission by an LED or a chime.

When the level of the received signal is larger than a certain threshold, the slave station CPU 3 drives the slave station side warning means 4 and simultaneously drives the transmission signal coded by the code generation circuit 30. It is driven by the circuit 5 and the encoded ultrasonic signal is transmitted from the slave station ultrasonic transceiver 1.

FIG. 9 (c) shows a case where a transmission ultrasonic signal is encoded using a 4-bit M-sequence code "1101" as an example.

An ultrasonic signal having a frequency f1 is a carrier in a portion to which a code "1" is added.

By increasing the number of bits, the accuracy of discriminating between a signal and noise is improved, but encoding is performed with an appropriate number of bits in consideration of the balance with the correlation function calculation time.

The code generation circuit 30 is composed of electronic devices such as various TTLs, and generates a predetermined code, for example, a digital signal “1101” in the above example.

When the code is transmitted to the driving circuit 5,
What is necessary is just to make it the structure which transmits an ultrasonic wave corresponding to the signal of "1".

For example, an electronic circuit such as a monostable multivibrator using the signal “1” as an input trigger signal can be used.

Note that the encoding method is not limited to the M-sequence, but various codes are conceivable.

The transmission of the ultrasonic waves is performed to the master station device E29, and the carrier frequency thereof is different (f1) from the transmission signal of the master station (see FIG. 9 (c)).

The transmission signal from the slave station device 6 is received by the master station ultrasonic receiver 8, and the time measurement by the time measurement timer 10 is stopped (see FIG. 9D).

The time measurement timer 10 allows the master station A1
The time Δt from transmission to reception of the ultrasonic wave No. 9 will be measured.

When the received signal is a signal from the slave station device 6, the distance between the master station device E29 and the slave station device 6 is obtained by equation (1), and the distance data is stored in the RAM 12. When the distance is equal to or less than a predetermined value, the signal processing DSP
17 sends a signal to the master station warning means 13 and sends a signal to the master station device A1.
The warning is given to the person who carries 9.

As a warning method, any means such as light emission by LED, chime warning, etc. may be used.

Further, regardless of the output of the warning, the period T
(For example, 150 (msec)), a new master station A
The transmission of the ultrasonic wave from is started (see FIG. 9E).

By the way, if the received signal is truly a transmission signal from the slave station device 6, the above-mentioned processing may be performed.
An erroneous warning due to extraneous noise is generated, and the reliability of the device is reduced.

Therefore, the received signal from the outside is changed to A /
After conversion into a digital signal by the D converter 16, it is determined whether or not the signal is external noise.

Hereinafter, description will be made with reference to FIG.

First, a plurality of received signal data (Xn) are accumulated, and the average (XA), the variance (σx)
Is calculated, and a normalization process is performed to make the distribution of the received data a normal distribution, thereby obtaining normalized process data X (n) (step 200).

Next, FFT processing is performed on the normalized data.

To perform the FFT processing, as described above, the WI
An NDOW process is performed (step 210).

Here, a Hamming window, which is generally used, is used as the window function.

The Hamming window function is given by equation (2).

Therefore, X (n) × W (n) obtained by multiplying X (n) by the window function W (n) is newly set as X (n) (step 210). Next, FFT processing is performed.

The result of the FFT processing of X (n) is obtained from Equation 3 as follows (step 220).

X (k) = ΣX (n) exp (−j2πnk / N) (where, Σ is a sum of n from n = 0 to N−1, j is an imaginary unit, and exp is Next, at step 230, cross power spectrum processing is performed.

Cross power spectrum Sxy (k)
Is obtained by the product (Equation 5) of X (k) and the conjugate complex number Y * (k) obtained by performing the FFT processing on the encoded data sequence.

Sxy (k) = X (k) · Y * (k) (Equation 5) If the encoding method is determined, the value of Y * (k) is calculated in advance, and the signal processing DSP 17 May be stored in a ROM area or the like.

Next, at step 240, Sxy (k)
Is performed, and finally, the correlation function Rxy
(M) is calculated (Equation 6).

Rxy (M) = (ΣSxy (k) exp (j2πnk / N)) / N (Equation 6) (where, Σ is the sum of n from n = 0 to N−1, j Represents an imaginary unit, and exp represents an exponential function.) Finally, when Rxy (M) is equal to or greater than a predetermined correlation threshold value L, a signal from a slave station is used. A determination is made (step 250).

Note that the threshold value L is obtained in advance by experiments, simulations, and the like.

By the above-described series of processing in the signal processing DSP 17, it is possible to accurately distinguish whether a received signal is an external noise or a transmission signal from a slave station.

According to the present invention as well, various external noises generated during construction and signals from slave stations can be accurately identified, and a driver such as a power shovel equipped with a master station can
Work can be performed while paying attention to warnings, which can improve work efficiency and safety.

[0200]

According to the present invention, the signal processing of the received wave in the master station can accurately discriminate the external noise from the transmission signal from the slave station, thereby providing a work warning device with less false warning.

Further, since it is possible to grasp which slave station frequently becomes in danger, it is possible to take preventive safety measures,
The direction in which the slave station exists can be recognized, and danger can be quickly avoided.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a configuration of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a conventional technique.

FIG. 3 is an explanatory diagram of the first embodiment of the present invention.

FIG. 4 is a process chart for explaining the function of the first embodiment of the present invention.

FIG. 5 is an explanatory diagram of a configuration of a second embodiment of the present invention.

FIG. 6 is an explanatory diagram of a configuration of a third embodiment of the present invention.

FIG. 7 is an explanatory diagram of a configuration of an example of the present invention.

FIG. 8 is an explanatory diagram of a configuration of an example of the present invention.

FIG. 9 is an explanatory diagram of an embodiment of the present invention.

FIG. 10 is a process chart for explaining the function of the embodiment of the present invention.

FIG. 11 is an explanatory diagram of an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Slave station ultrasonic transmitter / receiver, 2 ... Comparator, 3 ... Slave station side CPU, 4 ... Slave station side warning means, 5 ... Drive circuit, 6 ... Slave station apparatus, 7 ... Master station ultrasonic transmitter, 8 ... Master station ultrasonic receiver, 9: master station side CPU, 10: time measurement timer, 10A
... Time measurement timer, 10B ... Time measurement timer, 10C ...
Time measurement timer, 10D time measurement timer, 10E time measurement timer, 10F time measurement timer, 10G time measurement timer, 10H time measurement timer, 10I time measurement timer, 10J time measurement timer, 11 comparator 12: threshold setting circuit, 13: master station warning means, 1
4 ... Drive circuit, 15 ... Master station device, 16 ... A / D converter,
16A: A / D converter, 16B: A / D converter, 16C
... A / D converter, 16D ... A / D converter, 16E ... A /
D converter, 16F A / D converter, 16G A / D converter, 16H A / D converter, 16I A / D converter, 1
6J A / D converter, 17 Signal processing DSP, 18 R
AM, 19 ... master station device A, 20 ... master station device B, 21 ... master station device C, 22 ... receiver for f1, 23 ... receiver for f2,
24 first slave station device, 25 second slave station device, 26 display device, 27 threshold setting section, 28 master station device D, 29
... Master station device E, 30 ... Code generation circuit

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-368000 (JP, A) JP-A-4-70587 (JP, A) JP-A-4-74989 (JP, A) JP-A 64-64 12285 (JP, A) Japanese Utility Model 2-128972 (JP, U) Japanese Utility Model 5-33080 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01S 7/52-7 / 64 G01S 15/00-15/96 G08B 3/10

Claims (5)

(57) [Claims] 1. A master station comprising: a master station; and at least one slave station, wherein the master station transmits ultrasonic waves of a certain frequency, and receives ultrasonic waves of a frequency different from the transmission frequency. Means for analyzing the frequency component of the received wave; means for calculating the error between the first experimental value set in advance and the power spectrum of the received wave; and Means for determining whether a frequency is included, means for measuring the time from transmission to reception, and the square root of the sum of the square of the difference between the power spectrum of the received wave and the first experimental value is , A second experimental value or less, and further, only when the power spectrum of the received wave has a different frequency component received by the receiving means, means for judging a dangerous state from the measurement time from transmission to reception. , When determined to be dangerous The slave station further comprises: means for receiving a transmission signal from the master station; means for transmitting an ultrasonic wave having a frequency different from the transmission frequency of the master station; and Means for issuing a warning when the reception level is equal to or higher than a preset threshold value,
Work alarm. 2. The work alarm device according to claim 1, wherein the means for analyzing the frequency component of the received wave includes a threshold value setting means. 3. The work alarm according to claim 1, wherein the transmission frequency of the ultrasonic wave of the slave station differs for each slave station, and the master station also has receiving means corresponding to the frequency. apparatus. 4. The work alarm device according to claim 3, wherein the transmitting means and the receiving means of the master station are arranged in at least two directions. 5. A master station, comprising at least one slave station, said master station transmitting ultrasound, receiving an encoded ultrasound signal, and a correlation function of the received signal. Calculating means, means for measuring the time from transmission to receiving the encoded ultrasonic signal, and only when the calculation result of the correlation function calculating means is equal to or greater than a preset threshold value, Means for judging a danger state from the measurement time until reception, and means for warning when it is judged danger, further, said slave station, means for receiving a transmission signal from the master station, A work alarm device comprising: a unit for issuing a warning when a reception level of a transmission signal is equal to or higher than a preset threshold value; and a unit for transmitting an encoded ultrasonic signal.