KR200333857Y1 - A magnetic locator for locating buried objects by using magnetic markers - Google Patents

Abstract

Two fluxgate sensors for measuring the magnetic field generated by the magnetic marker to detect the magnetic field generated from the magnetic marker made of permanent magnet and attached to the underground buried more accurately and effectively, and the two A digital gradometer that outputs the mixed frequency of two waveforms as 8-bit parallel digital data through digital mixing of the sensor output, and a digital-analog that receives the digital data and generates the magnitude as an analog signal. The underground buried detector includes a converter, a voltage controlled oscillator for outputting the analog signal at a frequency that can be sensed by the hearing, and a voice amplifier for amplifying the analog signal so as to be transmitted to the external voice through a speaker.

Description

A magnetic locator for locating buried objects by using magnetic markers}

The present invention relates to an underground buried detector for more accurately measuring the location of underground buried by detecting a magnetic field generated from a magnetic marker made of permanent magnets attached to underground buried.

As urbanization progresses rapidly, the installation of water and sewage pipes, city gas supply pipes, and electric and communication lines is rapidly increasing to expand infrastructure such as electricity, telecommunications, and water and sewage. These facilities are mostly buried underground due to the beauty and protection of equipment. However, since the information on the location and depth of such underground deposits is not well prepared and it is difficult to grasp the location or state through vision, it is difficult to maintain the underground deposits. In addition, when installing new underground works or constructing a building, time and cost are increased to accurately locate the existing underground works, and when it is not known, the existing underground works are destroyed or under construction, It becomes dangerous.

Conventionally, in order to detect the location of the underground buried material, to detect underground buried material on the ground, the method of detecting the wavelength change propagated through the medium and buried material after propagating electromagnetic waves, ultrasonic waves, ultra-high frequency, etc. to the ground as a medium Was used. However, since this conventional technique is to locate the underground buried material by analyzing the frequency of the measured wavelength, it is necessary to make and apply complicated and difficult algorithms such as Fourier transform, error correction, and functional diagnostic test for analysis. There is a problem that requires expensive equipment for.

As another method, a magnetic coil is installed on an upper layer of underground buried material, and a method of detecting a magnetic field of current generated from a magnetic coil installed by a ground detector inducing magnetism has been proposed. However, this technique has a disadvantage in that it is difficult to locate the magnetic coil or lose the magnetic coil if the magnetic coil is incorrectly installed during the excavation and buried construction.

Therefore, in order to solve the above-mentioned problems, the present invention is constructed by attaching a magnetic marker made of permanent magnets to an underground buried material, and an underground buried detector which detects the location of underground buried material by measuring a magnetic field generated by the magnetic marker. For the purpose of providing it.

In addition, it detects the magnetic field generated by the magnetic marker and converts the size into digital data to facilitate the processing of numbers and graphics, and outputs the detection results in various visual forms. An object is to provide a buried material detection device.

In addition, the object of the present invention is to stably and accurately convert the detection result into not only digital data but also an analog signal of voice, and to provide an efficient and simple magnetic marker detector.

1 is an explanatory diagram of a method for detecting underground burial installed in underground burial;

2 is an overall configuration diagram of the underground buried detector of the present invention,

3 is a structural diagram of a fluxgate sensor according to an embodiment of the present invention;

4 is a structural diagram of a digital mixer for mixing two waveforms digitally;

5 is a circuit diagram of a digital gradometer according to an embodiment of the present invention,

6 is a configuration diagram of a voltage controlled oscillator according to an embodiment of the present invention;

7 is a waveform diagram of a voltage controlled oscillator according to an embodiment of the present invention;

8 is an overall circuit diagram of the underground buried detector according to an embodiment of the present invention,

9 is an arrangement diagram of a fluxgate sensor according to an embodiment of the present invention,

10 is an enlarged view of an output portion of a fluxgate sensor according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

10: underground buried detector 11: magnetic marker

12 flux sensor 13 output unit

18: underground buried 20: digital gradometer

22 microprocessor 24 LCD player

25 digital to analog converter 27 voltage controlled oscillator

28: voice amplifier 30: speaker

31: DC power supply 310: sensing coil

320: drive coil 330: circular magnetic core

410: output waveform of the sensor 420: Schmitt trigger

430: D flip-flop 610, 611: comparator

620, 621: transistor 630: integrator capacitor

910: Adjustment screw 950: L-C filter

Underground buried detector is the present invention for achieving the above object,

To measure the magnetic field generated from the magnetic markers, two fluxgate sensors with their axes in a straight line,

A digital gradometer for digitally mixing the two waveforms by inputting the outputs of the two fluxgate sensors, and outputting the mixed frequency of the two waveforms as 8-bit parallel digital data;

A digital-to-analog converter for receiving the 8-bit digital data and generating a magnitude thereof as an analog signal;

A voltage controlled oscillator for outputting an analog signal generated from a digital-analog transducer at a frequency at which hearing can be sensed;

It characterized in that it comprises a voice amplifier for amplifying the output of the voltage-controlled oscillator so that it can be sent to the external voice through the speaker.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily understand and reproduce the present invention.

1 illustrates a method of detecting underground burial installed in underground burial.

Magnetic marker (11) is a permanent life is produced by a permanent magnet (ferrite) of a constant magnetic force waterproof, moisture-proof, nickel plating, urethane coating coating, etc., water and sewage pipe, city gas supply pipe, electric and communication lines, etc. It is attached to this facility during the construction of the underground burial site 18.

Two fluxgate sensors 12 located in the support rod 15 constituting the underground buried detector 10 measure the magnetic field. Each fluxgate sensor 12 is a vector sensor and an average magnetic field corresponding to each sensing axis. Measure the ingredients. In addition, these fluxgate sensors 12 are positioned in different directions so that the polarities of the magnetic fields measured with each other are reversed, and when the signals measured by the fluxgate sensors 12 are summed, they are common to the two sensors like the geomagnetic field. It can remove the components that are detected and only the magnetic component of the difference remains. The magnetic field measured at the fluxgate sensor 12 near the magnetic marker 11 has a value much greater than that specified at the fluxgate sensor 12 located remotely. Therefore, these differences represent the magnetic field strength of the magnetic marker 11 having magnetic components, and the magnetic fields of the difference are measured by the speaker 13 or the LCD player 14 built in the underground buried detector 10. Express the strength and weakness of the magnetic field.

Figure 2 shows the overall configuration of the underground buried detector of the present invention.

As shown in FIG. 2, the two fluxgate sensors 12 are provided on the supporting rod 15 so that the shafts are straight. Each fluxgate sensor 12 measures the magnetic field generated by the magnetic marker 11 at its position, and inputs the measured magnetic field to the digital gradometer 20.

The digital gradometer 20 digitally mixes the magnetic field waveforms input from the two fluxgate sensors 12. That is, a frequency signal corresponding to the frequency difference between the two input signals is made, and the mixed frequency of the two waveforms is output as 8-bit parallel digital data.

Digital data output from the digital gradometer 20 is transmitted to the microprocessor 22 through the input interface 21 in order to output the number or graph. The microprocessor 22 receives a digital signal corresponding to the strength of the magnetic field, calculates the strength of the magnetic field generated by the magnetic marker 11, and the calculated value is an output interface 23 for driving the LCD player 24. ) Is expressed in the form of numbers or graphs on the LCD player 24.

In addition, the microprocessor 22 is connected to the GPS receiver 32 and the external system connector 33. The GPS receiver 32 may receive the current location of the underground burial detector 10 through GPS. The received location information is processed and stored by the microprocessor. External system connection unit 33 is connected to the external GIS system by wireless or wired to query the settings of the current measurement area. The microprocessor 22 refers to the digital data output from the digital gradometer 20 and, if it is confirmed that the magnetic marker 11 is embedded, receives the current position information from the GPS receiver and connects the external system connection unit ( 33) receive and receive the setting information corresponding to the current location from the external GIS system. In addition, the microprocessor 22 compares the location information with each setting beam, checks the setting information for the underground buried material, and outputs it in the form of a text or a graph to the LCD player 24 through the output interface 23.

In addition, the microprocessor 22 receives the current location information received through the GPS receiver 32 or the underground buried material to be searched by the user regardless of the presence or absence of the magnetic marker 11, and only the information is displayed on the LCD player ( 24) can be printed in text or graph format.

In addition, the digital data output from the digital gradometer 20 is sent to the input of the digital-to-analog converter 25 to output the external voice of intensity corresponding to the magnitude. The digital-to-analog converter 25 outputs the input 8-bit digital data in the form of an analog signal in the range of 0 to 2.5 V in size. The sensitivity controller 26 adjusts the sensitivity of the signal by adjusting the threshold voltage of the digital-to-analog converter 25.

The converted analog signal is processed by the voltage controlled oscillator 27 to be output at a frequency that can be heard again by the human hearing, amplified by the voice amplifier 28 and output through the speaker 30 to external voice. That is, the speaker 30 is used to express the magnitude of the signal difference, and in order to drive the speaker 30, a voltage controlled oscillator 27 for generating an oscillation frequency corresponding to the signal difference is required, and the speaker is driven by receiving the output thereof. A voice amplifier 28 is needed. The volume controller 29 connected to the voice amplifier 28 is for adjusting the volume of the speaker 30.

In addition, as shown in FIG. 1, the fluxgate sensor 12 and the digital gradometer 20 are supplied with + 5V by one constant voltage source, and the digital-to-analog converter 25 and the voltage controlled oscillator ( 27) and the voice amplifier 28 are driven by another constant voltage source. This separation of the voltage source is to prevent the sensor from malfunctioning due to the fluctuation of the constant voltage source.

3 illustrates the structure of the fluxgate sensor 12 according to an embodiment of the present invention.

As shown in FIG. 3, the fluxgate sensor 12 includes a circular magnetic core 330 that is periodically saturated by the drive coil 320 and a sense coil 310 that measures a magnetic field inside the coil. . The drive coil 320 is wound around the circular magnetic core 330, and the sense coil 310 is wound around the drive coil 320 in a transverse manner.

In general, the sense coil 310 does not detect the magnetic field generated by the toroidal drive coil 320, but if an additional external magnetic field is applied, the pure magnetic field generated by the hysteresis of the drive coil 320 is sensed. Detected by coil 310. With this special structure, the sensitivity to the external magnetic field is related to the direction of the sense coil 310.

The measurement range of the fluxgate sensor 12 is ± 50 μT (± 0.5) and has a resolution of about 10 nT (0.1mG). Therefore, the fluxgate sensor 12 can detect a very small change in the magnetic field sensitively. However, since the underground buried detector 10 detects the difference between the magnetic fields measured by using two fluxgate sensors 12 that are different from each other, the linearity of the sensor is not so important. The output of the fluxgate sensor 12 is an easy-to-use 5V square wave whose frequency varies depending on the magnitude of the magnetic field where the fluxgate sensor 12 is located, usually from 50 kHz to 120 kHz (period T = 8.5us to 25us) changes.

4 illustrates a structure of a digital mixer in which two waveforms are digitally mixed.

As described above, the underground burial detector 10 mixes the output frequencies from the two fluxgate sensors 12 to obtain a difference between the measured magnetic fields to generate a signal indicating the presence or absence of the magnetic marker 11. Mixing). 4 shows a circuit of a digital mixer performing this function.

5 shows a circuit of a digital gradometer 20 according to an embodiment of the present invention.

The digital gradient meter 20 takes the outputs of the two fluxgate sensors 12 as inputs and performs the digital mixing described above. The output from the digital gradient meter 20 is an 8-bit parallel data structure that varies with the magnitude of the mixed frequencies. It also has an output indicating the sign bit. This indicates which of the two fluxgate sensors 12 has a larger magnetic field. Therefore, the output "0" means that the two sensors detect the same size magnetic field, and the output of the highest value ("255") means that the magnetic field difference is large. Using a 9-bit output, including the sign bit, you can get an output of -255 to +255.

As shown in Figure 5, pin 1 provides two different sensitivity levels, either high or low, as an input. Two sensitivitys controlled by pin 1 are used to provide a range of large magnetic field changes. pin 2 provides the polarity signal at the output and can therefore represent a signed magnitude. This makes it possible to effectively read 9-bit outputs. pin 17 and pin 18 are inputs of signals output from the fluxgate sensor 12 and directly receive an output waveform of 5V. Pins 15 and 16 are for the crystal oscillation circuit and provide a stable reference value for measuring the periodic change of the fluxgate sensor 12. The remaining pins are mostly digital output bits, D0 through D7. It is used as an input to an external device such as a computer or microprocessor 22 or to a digital display 24 or a digital-to-analog converter 30.

The digital gradometer 20 depends on the crystal oscillator frequency but observes the maximum and minimum values of the geomagnetic field while automatically calibrating for 10 to 20 seconds from the time the switch is turned on. At this time, the digital gradometer 20 is arranged in the north-south direction, and the tip is inclined by the inclination angle of the geomagnetic field. Then, the switch is turned on and the digital gradometer 20 is rotated 180 ° for a calibration time (about 10 seconds) to determine the sensitivity and zero offset for the sensor and to correct the error resulting from the sensor difference.

8 is a circuit diagram of the underground buried detector 10 described as an embodiment of the present invention as a whole.

Next, the actual design of the voltage controlled oscillator 27 which is an important component of the underground buried detector 10 will be described in more detail. In order to clarify this detailed description, the description corresponding to the voltage controlled oscillator 27 of FIG. 8 in addition to FIGS. 6 and 7 will be described.

6 and 7 show the configuration of the voltage controlled oscillator 27 and the waveform generated on the circuit according to an embodiment of the present invention.

The voltage controlled oscillator 27 may be a general voltage controlled oscillator using an integrated circuit, but is not suitable for a very low power of 1 mA, and thus constitutes a simple but effective voltage dual comparator circuit as shown in FIG. 6. .

The first transistor 620 is inserted into the output amplifier to form feedback through the feedback resistor (1.6 K total) of the voltage controlled oscillator 27 and performs voltage / current conversion for driving the integrator capacitor 630. Integrator capacitor 630 generates a decreasing voltage, which is sensed by second comparator 611, and the decreasing voltage at node A of FIG. 6 is lower than the reference voltage of negative input B. The output C of the first comparator 610 is lowered so that the second transistor 621 is turned on, and the second transistor 621 shorts the integrator capacitor 630, which is the amount of node A. The voltage at the input of Vcc 2 is made and this process is repeated. The second comparator 611 generates an approximate square wave E by comparing the waveform generated at the node A of FIG. 6 with the midpoint magnitude D. FIG.

7 shows the various waveforms described above.

When the two fluxgate sensors 12 are in balance, the minimum output voltage of the voltage controlled oscillator 27 is 0 (V). This is the same value as when the voltage controlled oscillator 27 is not operated. In practice, however, since the two fluxgate sensors 12 are not perfectly balanced, the voltage controlled oscillator 27 always operates at any arbitrary low frequency. This is desirable because a continuous low frequency can be heard in the human ear, making it susceptible to small frequency changes. That is, by operating at a very low rate of change, minor changes can be detected. Typically 5 to 10 Hz is a good frequency. This range is clearly below the range of hearing (20 Hz). However, since the speaker waveform exists as a square wave as shown in FIG. 7E, it is possible to hear a high frequency component present in a pulse. The frequency of the voltage controlled oscillator 27 obtained as a result of this depends on the integrator current and the capacitor value and has the following relationship.

here Is the change in ramp voltage and I is the V _DAC / R _DAC . The reference of the first comparator 610 can be obtained from the level shift of the V _DAC and thus Is approximately equal to (V _CC -V _DAC -0.7). Neglecting resistor R6 in Figure 8, the frequency is

When V _DAC is zero, the minimum frequency is zero. When the voltage controlled oscillator 27 is from 0 to 1 LSB (0.0000001b, or 2.5V / 256), a very low frequency of about 5 Hz can be obtained.

That is, capacitor C = 0.28 kV. Using C5 = 0.47 Hz for the actual design, the LSB frequency is actually 3 Hz. When the V _DAC has a value of 2.5 V, the maximum frequency is

to be. Therefore, the output of the voltage controlled oscillator 27 has a frequency range from DC to 2 KHz according to the magnitude of the detected magnetic field.

9 illustrates an arrangement of a fluxgate sensor according to an embodiment of the present invention.

The most difficult part in maximizing the performance of the underground buried detector 10 is to mechanically arrange the two fluxgate sensors 12. The fixation of the fluxgate sensor 12 is to place one sensor exactly with the axis of another sensor. As shown in FIG. 9, one fluxgate sensor 12 is first fixed, and the other fluxgate sensor 12 is fixed by a fixing screw 910 having a nonmagnetic property. In this way, while rotating the sensor mechanism while rotating the fixing screw 910 to maintain a constant measured value while keeping the rotation of the two fluxgate sensor 12 to match the axis.

10 is an enlarged view of an output portion of the fluxgate sensor 12 according to an embodiment of the present invention.

Before connecting the fluxgate sensor 12 to the circuit device of the underground buried detector 10, the output of the fluxgate sensor 12 is filtered using the L-C filter 950 as shown in FIG. In this way, a clean signal free of noise can be obtained from the output square wave of the sensor.

As described above, the present invention can effectively and accurately determine the location of underground burial by detecting underground burial attached to underground burial such as water and sewage pipes, city gas supply pipes, electricity and communication lines. This makes it easier to maintain underground structures and to easily supervise the poor construction of underground structures, as well as the risk of damage or damage to existing underground structures when installing new underground structures or constructing buildings. You can lower your back.

In addition, the present invention can be easily detected because the operator outputs a voice that can be audible according to the magnitude of the magnetic field generated by the magnetic marker, in particular, even when the two fluxgate sensors in the state without the magnetic marker is balanced Continuous low frequencies can be heard in the human ear, making the operator sensitive to frequency changes.

In addition, the present invention mixes the magnetic field measured by two fluxgate sensors through a digital circuit and outputs digital data within a certain range. The digital data is processed by a commercial microprocessor and detected in various forms such as numbers and graphs. To print the output. Therefore, the detection operator can know the result more easily. The digital data can be used as basic data for analyzing the characteristics of the measured magnetic field in addition to various types of outputs. For example, it is possible to find out the state and position of the magnetic marker more accurately by examining and comparing a measurement value in advance by the position where the specific magnetic marker is embedded or the strength of the magnetic field. This can also make it easier to link underground buried detectors to underground buried management systems using GPS and GIS. In other words, using the GPS receiver built in the underground buried detector, it accurately records and stores the current detected location, and interlocks with the GIS system to search the buried information of the measurement area, compares and searches the buried location drawn by the measurement in advance. The results can be drawn on the screen of a personal computer or PDA attached to the magnetic detector, making it easy to work with the underground burial management system that visually locates the buried material.

In addition, the present invention provides a underground buried detector that is easy to carry and use, but also easy to carry and use by allowing the circuit to be composed of commercially available chips or the two fluxgate sensors to easily adjust the position of the shaft with a fixed screw.

Claims (9)

In order to detect the magnetic field generated from the magnetic marker 11 attached to the underground buried 15 to measure the position of the underground buried more accurately, Two fluxgate sensors 12 measuring the magnetic field generated from the magnetic marker 11, the axes being in a straight line; The outputs of the two fluxgate sensors 12 are configured as inputs, and a digital circuit is used to create a frequency corresponding to the frequency difference between the two signals. The mixed frequency of the two waveforms is output as 8-bit parallel digital data. A digital gradometer 20; A digital-to-analog converter (25) for receiving the 8-bit digital data and generating a magnitude thereof as an analog signal; A voltage controlled oscillator 27 for outputting an analog signal generated by the digital-analog transducer 25 at a frequency at which hearing can be sensed; A voice amplifier 28 for amplifying the output of the voltage controlled oscillator 27 so as to be sent to the external voice through the speaker 30; An underground buried detector, characterized in that it comprises a (10). 2. The two fluxgate sensors 12 are wound around a circular magnetic core 330, a drive coil 320 wound around the circular magnetic core 330, and transversely wound around the drive coil 320. Including the sensing coil 310, when a magnetic field is applied from the outside, the magnetic field generated by the hysteresis of the toroid is detected by the sensing coil 310, and the measuring range of the fluxgate sensor 12 is ± 50 μT (± 50G) and has a resolution of about 10 nT (0.1 mG), and the output of the fluxgate sensor 12 is a 5 V square wave and the frequency range is 50 kHz to 120 kHz (period T = 8.5 us to 25 us). Underground buried detector (10). 2. The digital gradometer 20 according to claim 1, while automatically calibrating for 10 to 20 seconds from the time when the switch is turned on, observes the maximum and minimum values of the geomagnetic field and sets the gradometer to 180 degrees. Underground detector (10), characterized in that by rotating the ° to determine the sensitivity and zero offset for the sensor and to correct the error coming from the sensor difference. The underground buried detector (10) of claim 1, wherein the digital-to-analog converter (25) outputs the input digital signal as an analog signal in the range of 0 to 2.5V. The method of claim 1, wherein the voltage controlled oscillator 27 uses a voltage dual comparator; A first and second comparators 610 and 611, first and second transistors 620 and 621, and an integrator capacitor 630; A first transistor 620 is inserted into the output amplifier to form feedback through a feedback resistor and to perform voltage / current conversion to drive the integrator capacitor 630; Integrator capacitor 630 generates a decreasing voltage, which is sensed by second comparator 611, and the decreasing voltage at node A of FIG. 6 is lower than the reference voltage of negative input B. FIG. The output C of the first comparator 610 is lowered so that the second transistor 621 is turned on, and the second transistor 621 shorts the integrator capacitor 630, which is the amount of node A. Make the voltage at the input of Vcc 2, and repeat this process; The second comparator 611 generates an approximate square wave E by comparing the waveform generated at the node A with the midpoint magnitude D. 10. 2. The first fluxgate sensor 12 is fixed and the second fluxgate sensor so that the two fluxgate sensors 12 align the two fluxgate sensors 12 exactly on the same axis. (12) underground buried detector (10), characterized in that to be fixed with a screw having the properties of non-magnetic material. The method of claim 1, wherein the flux gate sensor 12 is characterized in that the LC filter 950 is installed in the output portion of the fluxgate sensor 12 to filter the output and input to the digital gradient meter 20. Underground buried detector (10). The method according to claim 1, The underground deposit detector 10 includes an interface 21 for inputting the output of the digital gradometer 20 to the microprocessor. A microprocessor unit 22 for processing a signal output from the interface unit; an LCD player 24 for image outputting data output from the microprocessor; A GPS receiver 32 which receives a current position through GPS and inputs it to a microprocessor; An external system connection unit 33 for wirelessly or wirely connecting GIS information input from an external GIS system; The microprocessor receives the digital data output from the digital gradometer 20, records and stores the position received from the GPS receiver 32, and inquires every setting of the measurement area from an external GIS system. It is a microprocessor 22 for calculating the processing to output a number or a graph or by comparing and searching the received position and the setting beam, and outputs the setting beam corresponding to the received position to the LCD player 24; Characterized by the underground buried detector (10). The power supply for the fluxgate sensor 12 and the digital gradometer 20, the power supply for the digital-to-analog converter 25, the voltage controlled oscillator 27 and the voice amplifier 28. Underground buried detector, characterized in that for separating (10).