CN110989009B - High-sensitivity compensation type underground metal unexplosive object detection device and detection method - Google Patents
High-sensitivity compensation type underground metal unexplosive object detection device and detection method Download PDFInfo
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- CN110989009B CN110989009B CN201911181050.3A CN201911181050A CN110989009B CN 110989009 B CN110989009 B CN 110989009B CN 201911181050 A CN201911181050 A CN 201911181050A CN 110989009 B CN110989009 B CN 110989009B
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- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V3/00—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
- G01V3/08—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices
- G01V3/10—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices using induction coils
- G01V3/104—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices using induction coils using several coupled or uncoupled coils
- G01V3/105—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices using induction coils using several coupled or uncoupled coils forming directly coupled primary and secondary coils or loops
- G01V3/107—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices using induction coils using several coupled or uncoupled coils forming directly coupled primary and secondary coils or loops using compensating coil or loop arrangements
Abstract
The invention relates to a high-sensitivity compensation type underground metal nonexplosive object detection device and a detection method, wherein the device comprises a first receiving coil and a second receiving coil which have the same structure, are symmetrically arranged at two ends of a transmitting coil up and down and are connected in parallel in a differential mode; the controllable tuning module, the first receiving coil and the second receiving coil form a resonant circuit; the transmitting controller controls the transmitting coil to excite; the receiving controller and the transmitting controller are synchronous, a switch in one path of the controllable harmonic matching module is controlled to be closed through six-channel isolation driving according to transmitting frequency, and the differential amplifier amplifies an output signal of the controllable harmonic matching module; the double-receiving coil structure is adopted, and the influence of a primary transmitting field and environmental electromagnetic noise is eliminated by using a differential structure, so that the detection sensitivity of the metal abnormal body is improved. The invention can further improve the detection sensitivity by removing the background field, can meet the requirements of different detection depths by adopting multi-frequency emission, and can quickly and accurately position the position of the metal abnormal body.
Description
Technical Field
The invention relates to the field of underground metal nonexplosive substance detection, in particular to a high-sensitivity compensation type underground metal nonexplosive substance detection device and a detection method.
Background
The method has important significance for reliable and effective positioning detection of underground metal unexploded objects, and is highly valued by various countries. Most of the current detecting instruments are based on the electromagnetic induction principle, and carry out positioning and judgment by observing secondary field signals generated by the eddy current effect of unexploded metal in a receiving device. However, the current detection device and method still cannot meet the practical requirements in the aspects of detection sensitivity, detection efficiency, detection depth and detection reliability, and the specific defects are mainly reflected in the following aspects.
Firstly, a receiving coil is influenced by a primary field of a transmitting coil, so that a receiving device obtains main components of a primary field station in signals, a secondary field is small, and particularly when the volume of metal unexploded objects is small or the buried depth is large, effective signals are difficult to detect, namely the effective signals are influenced by transmission, the detection sensitivity is reduced, and even the detection fails; secondly, the electromagnetic noise of the external environment and the background field of the underground rock stratum can submerge secondary field signals generated by metal non-explosive substances; thirdly, most of the current detection devices are based on a single-frequency or dual-frequency emission mode, the detection depth is shallow, and the problem of poor detection sensitivity exists.
Disclosure of Invention
Aiming at the defects of the prior art, the invention adopts the idea of symmetrically arranging a receiving coil at two sides of a transmitting coil to remove the interference of a primary field and a background field, and amplifies a received secondary field signal through LC resonance, thereby providing the high-sensitivity compensation type underground metal nonexplosive substance detection device and the high-sensitivity compensation type underground metal nonexplosive substance detection method.
The present invention is achieved in such a way that,
a high sensitivity compensated underground metal nonexplosive detection device, the device comprising: the receiving controller is isolated from the industrial personal computer, the transmitting controller and the six-channel drive, and comprises a controllable harmonic module, a differential amplifier, a transmitting coil and a receiving coil, wherein the receiving coil comprises a first receiving coil, a second receiving coil and a third receiving coil;
the first receiving coil and the second receiving coil have the same structural parameters and are symmetrically arranged at two ends of the transmitting coil up and down, and the first receiving coil and the second receiving coil are connected in a differential parallel mode;
the controllable harmonic matching module comprises six groups of switches connected in series and a matching capacitor which are connected in parallel, and forms a resonant circuit with the first receiving coil and the second receiving coil;
a transmitting controller for the transmitting circuit to be excited by the transmitting coil;
the industrial personal computer is used for man-machine interaction, and an operator sends system parameters and control instructions to the receiving controller through the industrial personal computer;
the receiving controller is used for sending a control instruction and system parameters to the transmitting controller; for sending a synchronization signal to the transmit controller; according to the transmitting frequency, one path of switch in the controllable harmonic matching module is controlled to be closed through six-channel isolation driving, and other paths of switches are controlled to be opened;
the differential amplifier is used for amplifying the output signal of the controllable harmonic matching module;
a first band pass filter for filtering an output signal of the differential amplifier;
the six-channel isolation drive drives the controllable harmonic matching module according to the instruction of the receiving controller;
and the third receiving coil is coaxial with the first receiving coil and the second receiving coil, is arranged between the first receiving coil or the second receiving coil and the transmitting coil, is used for receiving the primary field signal and the background field, is compared with the differential output signals of the first receiving coil and the second receiving coil, and verifies the compensation effect on the primary field and the background field.
Furthermore, the transmitting coil is fixed on the non-metal cylinder, the first receiving coil, the second receiving coil and the transmitting coil are coaxially and equidistantly arranged on two sides of the non-metal cylinder in parallel, and the distance between the two receiving coils is dDThe number of turns of the coil is nDAnd adjusting according to the actual detection requirement.
Further, the transmitting frequency f and the sampling times n are sent to the receiving controller through the industrial personal computer, the receiving controller adjusts the capacitance according to the frequency and adjusts a switch in the controllable tuning module, so that the circuit is in a resonance state, and the following formula is met:
the sensitivity is then adjusted according to the following formula.
Uc＝QU
f: transmission frequency, Q: quality factor, C: capacitance value in the access circuit in the controllable tuning module, R: equivalent resistance of the first receiving coil and the second receiving coil, L is equivalent inductance of the first receiving coil and the second receiving coil, Uc: the voltage at the two ends of the capacitor is the output voltage of the two receiving coils, U: the difference between the induced voltages of the two receiving coils.
Further, the transmission circuit includes: the DC-DC conversion module, the drive circuit, the current transformer and the A/D converter;
the DC-DC conversion module is used for voltage conversion and providing stable voltage for the driving circuit;
the current transformer is used for collecting the current of the transmitting coil;
the A/D converter is used for analog-to-digital conversion, converting the measured current analog signal into a digital signal and transmitting the digital signal to the transmitting controller;
the transmitting controller controls the DC-DC conversion module to enable the driving circuit to be excited through the transmitting coil; and the current transformer is used for receiving and displaying current signals acquired by the current transformer and converted by the A/D converter.
Further, the device also comprises:
the first program control amplifier receives and is used for controllably amplifying the output signal of the first band-pass filter;
the preamplifier is used for amplifying the primary field signal received by the third receiving coil;
the second band-pass filter is used for filtering the output signal of the preamplifier;
the second program control amplifier is used for controllably amplifying the output signal of the second band-pass filter;
and the data acquisition card is used for analog-to-digital conversion, converting analog signals processed by the first program control amplifier and the second program control amplifier into digital signals under the trigger of a synchronous signal, and transmitting the digital signals to the industrial personal computer.
Further, the device also comprises a processor for receiving the data of the industrial personal computer and exciting the frequency f according to different excitation frequenciesnN is 1, 2, 3, 4, 5, 6 secondary field signal s generated by underground rock stratumnN is 1, 2, 3, 4, 5, 6 and serves as a background field, where f1＝8Hz、f2＝32Hz、f3＝128Hz、f4＝1024Hz、f5＝3624Hz、f610842Hz, different frequencies correspond to different depths of investigation hnFrequency f1Minimum, corresponding probe depth h1Maximally, acquiring a pure secondary field generated by metal unexplosive substances;
according to the transmission frequency f2、f5Secondary field induced signal s of time coil output2'，s5', determine | s2'-s2I and s5'-s5If the | is close to 0, if yes, determining that no metal object exists in the current measuring point, and moving the detection device to perform next measurement detection;
comparison | s2'-s2I and s5'-s5L, the former being large, the measured transmission frequency being f1、f3Secondary field induced signal s of time coil output1'、s3', then will | s1'-s1|、|s2'-s2|、|s3'-s3Comparing | the metal non-explosive substances are near the depth corresponding to the maximum value; if the latter is large, the measured transmission frequency is f4、f6Secondary field induced signal s of time coil output4'、s6', then will | s4'-s4|、|s5'-s5|、|s6'-s6For comparison, the metal is near the depth corresponding to the maximum.
A high sensitivity compensated underground metal nonexplosive detection method comprising:
1) and setting up a coil structure: with a radius of RTThe transmitting coil is fixed on the non-metal cylinder and has a radius of RDThe first receiving coil and the second receiving coil are coaxially and equidistantly arranged at two sides of the transmitting coil, and the distance between the two receiving coils is dDThe number of turns of the coil is nDAdjusting the parameters according to actual detection requirements;
2) acquiring a background field: acquiring local geological conditions of 0-100m by drilling, and obtaining different excitation frequencies f by forward modeling according to specific parameters in the step 1)nN-1, 2, 3, 4, 5, 6, secondary field signal s generated by the subsurface formationn，n＝1，2，3，4，5，6，And as a background field, wherein f1＝8Hz、f2＝32Hz、f3＝128Hz、f4＝1024Hz、f5＝3624Hz、f610842Hz, different frequencies correspond to different depths of investigation hnFrequency f1Minimum, corresponding probe depth h1Maximally, acquiring a pure secondary field generated by metal unexplosive substances;
3) rapid determination of the presence of metallic non-explosives: measuring the transmission frequency f separately2、f5Secondary field induced signal s of time coil output2'，s5', determine | s2'-s2I and s5'-s5If the | is close to 0, if so, determining that no metal object exists in the current measuring point, and moving the detection device to perform next measurement detection; otherwise, carrying out the next step;
4) comparison | s2'-s2I and s5'-s5If the former is large, the measured transmission frequency is f1、f3Secondary field induced signal s of time coil output1'、s3', then will | s1'-s1|、|s2'-s2|、|s3'-s3Comparing | the metal non-explosive substances are near the depth corresponding to the maximum value; if the latter is large, the measured transmission frequency is f4、f6Secondary field induced signal s of time coil output4'、s6', then will | s4'-s4|、|s5'-s5|、|s6'-s6For comparison, the metal is near the depth corresponding to the maximum.
Further, the measuring process of the secondary field induction signal in the step 3) and the step 4) is as follows:
a. transmitting the transmitting frequency f and the sampling times n to a receiving controller through an industrial personal computer, and adjusting a capacitor by the receiving controller according to a switch in a frequency adjusting controllable tuning module to enable a circuit to be in a resonance state;
b. sending a collection instruction: sending an excitation and acquisition instruction to a receiving controller through an industrial personal computer, and sending an excitation instruction to a transmitting controller by the receiving controller;
c. emitting a sine wave: the receiving controller sends a synchronous signal to the transmitting controller, the transmitting controller outputs stable voltage through the DC-DC conversion module, and the transmitting controller transmits frequency f and amplitude I to the transmitting coil through the driving circuitTThe sine wave of (1);
d. collecting signals: receiving a primary field signal through a third receiving coil, amplifying the primary field signal through a preamplifier, filtering the primary field signal through a second band-pass filter, carrying out controllable amplification through a second program control amplifier, transmitting the amplified primary field signal to an acquisition card, and then transmitting the amplified primary field signal to an industrial personal computer for storage; the signal acquisition card is used for acquiring signals of a program control amplifier, and the signals are transmitted to an industrial personal computer for storage through a receiving controller;
e. and (3) superposition measurement: and c, repeatedly executing the steps c and d according to the stacking times set in the step a until the stacking is finished.
Further, the transmitting frequency f and the sampling times n are sent to the receiving controller through the industrial personal computer, the receiving controller adjusts the capacitance according to the frequency and adjusts a switch in the controllable tuning module, so that the circuit is in a resonance state, and the following formula is met:
the sensitivity is then adjusted according to the following formula.
Uc＝QU
f: transmission frequency, Q: quality factor, C: capacitance value in the access circuit in the controllable tuning module, R: equivalent resistance of the first receiving coil and the second receiving coil, L, equivalent inductance of the first receiving coil and the second receiving coil, Uc: the voltage at two ends of the capacitor is the output voltage of the two receiving coils, U: the difference between the induced voltages of the two receiving coils.
Compared with the prior art, the invention has the beneficial effects that:
(1) the high-sensitivity compensation type underground metal unexplosive object detection device provided by the invention adopts the double receiving coils to be arranged at the concentric symmetrical positions at the two sides of the transmitting coil, eliminates the influence of a primary transmitting field and environmental electromagnetic noise by using a differential structure, and improves the detection sensitivity of a metal abnormal body.
(2) The high-sensitivity compensation type underground metal unexplosive object detection device provided by the invention adopts the LC resonance technology, so that the differential signals output by the double receiving coils are amplified, and the detection sensitivity of the detection device is further improved.
(3) According to the high-sensitivity compensation type detection method for the metal unexploded objects, the detection sensitivity can be further improved by removing the background field, the requirements of different detection depths can be met by adopting multi-frequency emission, and the position of the metal abnormal body can be quickly and accurately positioned by using an efficient working method.
Additional aspects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
FIG. 1 is a schematic diagram of the system structure and coil laying method of the present invention;
FIG. 2 illustrates the connection of the receiver coil of the present invention;
FIG. 3 illustrates the overall workflow of the proposed method of operation;
fig. 4 shows a method flow of the detection device in the overall working method proposed by the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
As shown in figure 1, a high-sensitivity compensation type underground metal unexplosive substance detection device comprises a receiving controller 10, an industrial personal computer 9, a transmitting controller 6 and a six-channel isolation drive 18, a storage battery 21 is connected with the industrial personal computer 9 and a DC-DC conversion module 5 to provide electric energy, a data acquisition card 11 is connected with a first program control amplifier 12, a second program control amplifier 17 and the industrial personal computer 9 and used for acquiring signals of the first program control amplifier 12 and the second program control amplifier 17 and transmitting the signals to the industrial personal computer 9, the first program control amplifier 12 is connected with a first band-pass filter 14 and the industrial personal computer 9 and transmitting the acquired signals to the industrial personal computer after amplification and filtering, a differential amplifier 13 is connected with a controllable harmonic matching module 20 and a first band-pass filter 14, the controllable harmonic matching module 20 is connected with the six-channel isolation drive 18 and driven by the six-channel isolation drive 18, one end of the controllable harmonic matching module 20 is connected with a first receiving coil, The other end of the second receiving coil 2 is connected with one end of the first receiving coil 1, the other end of the second receiving coil 2 is connected with a power ground, the third receiving coil 19 is connected with the second preamplifier 15, the second band-pass filter 16 is connected with the preamplifier 15 and the second program control amplifier 17, the DC-DC conversion module 5 is connected with the driving circuit 4 and the transmitting controller 6, the transmitting coil 3 is connected with the driving circuit 4 and the current transformer 8, the A/D converter 7 is connected with the current transformer 8 and the transmitting controller 6, and the transmitting controller 6 is connected with the industrial personal computer 9.
The connection mode of the first receiving coil 1 and the second receiving coil 2 is as shown in fig. 2, the two receiving coils have the same structural parameters and are placed at two ends of the transmitting coil in an up-down symmetrical manner, the transmitting coil is fixed on the non-metal cylinder, the first receiving coil, the second receiving coil and the transmitting coil are placed at two sides of the non-metal cylinder in parallel and coaxially and equidistantly, and the first receiving coil 1 and the second receiving coil 2 are connected in parallel in a differential manner, so that primary fields induced by the coupling of the transmitting coil of the two receiving coils are completely the same, the primary field of one receiving coil is compensated by the primary field of the other receiving coil, namely, the primary fields contained in the differential output signals of the two receiving coils are completely cancelled, and are also compensated and cancelled by external electromagnetic noise, and secondary fields with different amplitudes are generated due to the fact that underground metal is not an explosive and the underground rock stratum are different from the two, namely, the differential output signals of the two receiving coils only contain secondary fields generated by underground metal nonexplosive substances;
the controllable matching module 20 comprises six switches and six matching capacitors, and is divided into six groups which are connected in parallel, each group comprises the switches and the matching capacitors which are connected in series, the corresponding matching capacitors C are connected according to corresponding transmitting frequencies, and form a resonance circuit with the first receiving coil and the second receiving coil, so that the output signal amplitude is improved, the sensitivity is improved, the module can correspond to the six transmitting frequencies, and further, the large-range high-sensitivity detection of metal unexplosive substances from a shallow layer to a deep layer can be realized;
the transmitting controller is used for controlling the DC-DC conversion module 5 to enable the driving circuit 4 to be excited through the transmitting coil 3; and current signals acquired by the current transformer 8 and converted by the A/D converter 7 are received and displayed.
The DC-DC conversion module 5 is used for voltage conversion and providing stable voltage for the driving circuit 4;
the current transformer 8 is used for collecting the current of the transmitting coil;
the A/D converter 7 is used for analog-to-digital conversion, converting an analog signal measured by the current transformer 8 into a digital signal and transmitting the digital signal to the transmitting controller 6;
the industrial personal computer 9 is used for man-machine interaction, and an operator sends system parameters and control instructions to the receiving controller 10 through the industrial personal computer 9; the data acquisition card is used for displaying the working mode of the system and storing the signals acquired by the data acquisition card 11; adjustment of parameters for the programmable amplifier 12;
the receiving controller 10 is used for sending control instructions and system parameters to the transmitting controller 6; for sending a synchronization signal to the transmit controller 6; controlling the triggering of the data acquisition card 11; according to the transmitting frequency, a switch in one path of the controllable harmonic matching module 20 is controlled to be closed through the six-channel isolation driver 18, and switches in other paths are controlled to be opened;
the data acquisition card 11 is used for analog-to-digital conversion, converting the processed analog signals into digital signals under the trigger of synchronous signals, and transmitting the digital signals to the industrial personal computer 9, and the data acquisition card 11 respectively acquires signals of the first program control amplifier and the second program control amplifier;
a first programmable amplifier 12 for controllably amplifying the output signal of the band-pass filter 14;
the differential amplifier 13 is used for amplifying the output signal of the controllable tuning module 20 and transmitting the amplified output signal to the first band-pass filter 14;
a first band-pass filter 14 for filtering the output signal of the differential amplifier 13;
the third receiving coil 19 is coaxial with the first receiving coil and the second receiving coil, is arranged between the first receiving coil or the second receiving coil and the transmitting coil, is wound on the nonmetal cylinder, is used for receiving the primary field signal and the background field, is compared with the differential output signal of the first receiving coil 1 and the second receiving coil 2, and verifies the compensation effect on the primary field and the background field;
a preamplifier 15 for amplifying the primary field signal received by the third receiving coil 19;
a second band-pass filter 16 for filtering the output signal of the preamplifier 15;
the second program-controlled amplifier 17 is used for controllably amplifying the output signal of the second band-pass filter 16;
a six-channel isolation driver 18 for driving the controllable tuning module 20 according to the instruction of the receiving controller 10; the device also comprises a processor for receiving the data of the industrial personal computer and exciting the frequency f according to different excitation frequenciesnN is 1, 2, 3, 4, 5, 6 secondary field signal s generated by underground rock stratumnN is 1, 2, 3, 4, 5, 6 and serves as a background field, where f1＝8Hz、f2＝32Hz、f3＝128Hz、f4＝1024Hz、f5＝3624Hz、f610842Hz, different frequencies correspond to different depths of investigation hnFrequency f1Minimum, corresponding probe depth h1Maximally, acquiring a pure secondary field generated by metal unexplosive substances;
according to the transmission frequency f2、f5Secondary field induced signal s of time coil output2'，s5', determine | s2'-s2I and s5'-s5If the | approaches to 0, if yes, determining that no metal object exists in the current measuring point, and moving the detection device to perform the next measurementDetecting quantity;
comparison | s2'-s2I and s5'-s5L, the former being large, the measured transmission frequency being f1、f3Secondary field induced signal s of time coil output1'、s3', then will | s1'-s1|、|s2'-s2|、|s3'-s3Comparing | the metal non-explosive substances are near the depth corresponding to the maximum value; if the latter is large, the measured transmission frequency is f4、f6Secondary field induced signal s of time coil output4'、s6', then will | s4'-s4|、|s5'-s5|、|s6'-s6For comparison, the metal is near the depth corresponding to the maximum.
Referring to fig. 3, a high-sensitivity compensation type underground metal nonexplosive substance detection method comprises the following steps:
(1) and setting up a coil structure: with a radius of RTThe transmitting coil is fixed on the non-metal cylinder and has a radius of RDThe first receiving coil and the second receiving coil are coaxially and equidistantly arranged at two sides of the transmitting coil, and the distance between the two receiving coils is dDThe number of turns of the coil is nDThe parameters can be adjusted according to actual detection requirements;
(2) acquiring a background field: acquiring local geological conditions of 0-100m through drilling, and obtaining different excitation frequencies f through forward modeling according to specific parameters in the step (1)n(n-1, 2, 3, 4, 5, 6) secondary field signal s generated by a subterranean formationn(n-1, 2, 3, 4, 5, 6) and as a background field, wherein f1＝8Hz、f2＝32Hz、f3＝128Hz、f4＝1024Hz、f5＝3624Hz、f610842Hz, different frequencies correspond to different depths of investigation hnFrequency f1Minimum, corresponding probe depth h1Maximally, subtracting the background field from the signal collected in the actual detection for obtaining the background field, so as to obtain a pure secondary field generated by metal non-explosive substances;
(3) quick determination of presence or absence of metallic non-explosive substanceDetermining: measuring the transmission frequency f separately2、f5Secondary field induced signal s of time coil output2'，s5', determine | s2'-s2I and s5'-s5If the | is close to 0, if so, determining that no metal object exists in the current measuring point, and moving the detection device to perform next measurement detection; otherwise, carrying out the next step;
(4) determination of metal non-explosive positions: comparison | s2'-s2I and s5'-s5If the former is large, the measured transmission frequency is f1、f3Secondary field induced signal s of time coil output1'、s3', then will | s1'-s1|、|s2'-s2|、|s3'-s3Comparing | the metal non-explosive substances are near the depth corresponding to the maximum value; if the latter is large, the measured transmission frequency is f4、f6Secondary field induced signal s of time coil output4'、s6', then will | s4'-s4|、|s5'-s5|、|s6'-s6Comparing | the metal is near the depth corresponding to the maximum value;
referring to fig. 4, the specific working flow of the detection device in steps (3) and (4) is as follows:
a. setting parameters: an operator sends the transmitting frequency f and the sampling frequency n to the receiving controller 10 through the industrial personal computer 9, the receiving controller 10 adjusts the capacitance according to the frequency and adjusts the switch in the controllable tuning module 20, so that the circuit is in a resonance state, and the following formula is satisfied:
the sensitivity is then adjusted according to the following formula.
Uc＝QU
f: transmission frequency, Q: quality factor, C: capacitance value in the access circuit in the controllable tuning module, R: equivalent resistance of the first receiving coil and the second receiving coil, L is equivalent inductance of the first receiving coil and the second receiving coil, and U is equivalent resistance of the first receiving coil and the second receiving coilc: the voltage across the capacitor, i.e. the output voltage of the two receiving coils, U: difference between induced voltages of two receiving coils
b. Sending a collection instruction: an operator sends an excitation and acquisition instruction to the receiving controller 10 through the industrial personal computer 9, and the receiving controller 10 sends an excitation instruction to the transmitting controller.
c. Emitting a sine wave: the receiving controller 10 sends a synchronous signal to the transmitting controller 6, the transmitting controller 6 outputs a stable voltage through the DC-DC conversion module 5, and transmits a signal with a frequency f and an amplitude I to the transmitting coil 3 through the driving circuit 4TOf (c) is a sine wave.
d. Collecting signals: the receiving device receives the primary field signal through a third receiving coil 19, the primary field signal is amplified through a preamplifier 15 and filtered through a second band-pass filter 16, and a second program control amplifier 17 performs controllable amplification and transmits the signal to the data acquisition card 11, and then transmits the signal to the industrial personal computer 9 for storage; the first receiving coil 1 and the second receiving coil 2 collect the secondary field signals, the signals are amplified through the adjustable tuning module 20, then the signals of the second program control amplifier 12 are collected through the signal amplification data acquisition card 11 through the differential amplifier 13, and the signals are sent to the industrial personal computer 9 for storage through the receiving controller 10.
e. And (3) superposition measurement: and c, repeatedly executing the steps c and d according to the stacking times set in the step a until the stacking is finished.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (7)
1. A high sensitivity compensated underground metal unexplosive detector apparatus, comprising: the receiving controller is isolated from the industrial personal computer, the transmitting controller and the six-channel drive, and comprises a controllable harmonic module, a differential amplifier, a transmitting coil and a receiving coil, wherein the receiving coil comprises a first receiving coil, a second receiving coil and a third receiving coil;
the first receiving coil and the second receiving coil have the same structural parameters and are symmetrically arranged at two ends of the transmitting coil up and down, and the first receiving coil and the second receiving coil are connected in a differential parallel mode;
the controllable harmonic matching module comprises six groups of switches connected in series and a matching capacitor which are connected in parallel, and forms a resonant circuit with the first receiving coil and the second receiving coil;
a transmitting controller for the transmitting circuit to be excited by the transmitting coil;
the industrial personal computer is used for man-machine interaction, and an operator sends system parameters and control instructions to the receiving controller through the industrial personal computer;
the receiving controller is used for sending a control instruction and system parameters to the transmitting controller; for sending a synchronization signal to the transmit controller; according to the transmitting frequency, one path of switch in the controllable harmonic matching module is controlled to be closed through six-channel isolation driving, and other paths of switches are controlled to be opened;
the differential amplifier is used for amplifying the output signal of the controllable harmonic matching module;
a first band pass filter for filtering an output signal of the differential amplifier;
the six-channel isolation drive drives the controllable harmonic matching module according to the instruction of the receiving controller;
the third receiving coil is coaxial with the first receiving coil and the second receiving coil, is arranged between the first receiving coil or the second receiving coil and the transmitting coil, is used for receiving the primary field signal and the background field, is compared with the differential output signals of the first receiving coil and the second receiving coil, and verifies the compensation effect on the primary field and the background field;
the device also comprises a processor for receiving the data of the industrial personal computer and exciting the frequency f according to different excitation frequenciesnN is 1, 2, 3, 4, 5, 6 secondary field signal s generated by underground rock stratumnN is 1, 2, 3, 4, 5, 6, and doIs a background field, wherein f1＝8Hz、f2＝32Hz、f3＝128Hz、f4＝1024Hz、f5＝3624Hz、f610842Hz, different frequencies correspond to different depths of investigation hnFrequency f1Minimum, corresponding probe depth h1Maximally, acquiring a pure secondary field generated by metal unexplosive substances;
according to the transmission frequency f2、f5Secondary field induced signal s of time coil output2'，s5', determine | s2'-s2I and s5'-s5If the | is close to 0, if yes, determining that no metal object exists in the current measuring point, and moving the detection device to perform next measurement detection;
comparison | s2'-s2I and s5'-s5L, the former being large, the measured transmission frequency being f1、f3Secondary field induced signal s of time coil output1'、s3', then will | s1'-s1|、|s2'-s2|、|s3'-s3Comparing, wherein the metal nonexplosive object is near the depth corresponding to the maximum value; if the latter is large, the measured transmission frequency is f4、f6Secondary field induced signal s of time coil output4'、s6', then will | s4'-s4|、|s5'-s5|、|s6'-s6For comparison, the metal unexploded matter is near the depth corresponding to the maximum value.
2. The apparatus of claim 1, wherein the transmitter coil is fixed to the non-metallic cylinder, the first receiver coil, the second receiver coil and the transmitter coil are coaxially and equidistantly placed on both sides of the non-metallic cylinder in parallel, and the distance between the two receiver coils is dDThe number of turns of the coil is nDAnd adjusting according to the actual detection requirement.
3. The device of claim 1, wherein the transmitting frequency f and the sampling times n are sent to the receiving controller through the industrial personal computer, and the receiving controller adjusts the capacitance by adjusting a switch in the controllable tuning module according to the frequency so as to enable the circuit to be in a resonance state, and the following formula is satisfied:
the sensitivity is then adjusted according to the following formula:
Uc＝QU
f: transmission frequency, Q: quality factor, C: capacitance value in the access circuit in the controllable tuning module, R: equivalent resistance of the first receiving coil and the second receiving coil, L is equivalent inductance of the first receiving coil and the second receiving coil, Uc: the voltage at the two ends of the capacitor is the output voltage of the two receiving coils, U: the difference between the induced voltages of the two receiving coils.
4. The apparatus of claim 1, wherein the transmit circuit comprises: the DC-DC conversion module, the drive circuit, the current transformer and the A/D converter;
the DC-DC conversion module is used for voltage conversion and providing stable voltage for the driving circuit;
the current transformer is used for collecting the current of the transmitting coil;
the A/D converter is used for analog-to-digital conversion, converting the measured current analog signal into a digital signal and transmitting the digital signal to the transmitting controller;
the transmitting controller controls the DC-DC conversion module to enable the driving circuit to be excited through the transmitting coil; and the current transformer is used for receiving and displaying current signals acquired by the current transformer and converted by the A/D converter.
5. The apparatus of claim 1, wherein the apparatus further comprises:
the first program control amplifier receives and is used for controllably amplifying the output signal of the first band-pass filter;
the preamplifier is used for amplifying the primary field signal received by the third receiving coil;
the second band-pass filter is used for filtering the output signal of the preamplifier;
the second program control amplifier is used for controllably amplifying the output signal of the second band-pass filter;
and the data acquisition card is used for analog-to-digital conversion, converting analog signals processed by the first program control amplifier and the second program control amplifier into digital signals under the trigger of a synchronous signal, and transmitting the digital signals to the industrial personal computer.
6. A method for high sensitivity compensated underground metal unexplosive detection, comprising:
1) and setting up a coil structure: with a radius of RTThe transmitting coil is fixed on the non-metal cylinder, the first receiving coil and the second receiving coil with the radius of R are coaxially and equidistantly arranged on two sides of the transmitting coil, and the distance between the two receiving coils is dDThe number of turns of the coil is nDAdjusting the parameters according to actual detection requirements;
2) acquiring a background field: acquiring local geological conditions of 0-100m by drilling, and obtaining different excitation frequencies f by forward modeling according to specific parameters in the step 1)nN-1, 2, 3, 4, 5, 6, secondary field signal s generated by the subsurface formationnN is 1, 2, 3, 4, 5, 6 and serves as a background field, where f1＝8Hz、f2＝32Hz、f3＝128Hz、f4＝1024Hz、f5＝3624Hz、f610842Hz, different frequencies correspond to different depths of investigation hnFrequency f1Minimum, corresponding probe depth h1Maximally, acquiring a pure secondary field generated by metal unexplosive substances;
3) rapid determination of the presence of metallic non-explosives: measuring the transmission frequency f separately2、f5Second of time coil outputField induced signal s2'，s5', determine | s2'-s2I and s5'-s5If the | is close to 0, if so, determining that no metal object exists in the current measuring point, and moving the detection device to perform next measurement detection; otherwise, carrying out the next step;
4) comparison | s2'-s2I and s5'-s5If the former is large, the measured transmission frequency is f1、f3Secondary field induced signal s of time coil output1'、s3', then will | s1'-s1|、|s2'-s2|、|s3'-s3Comparing | the unexploded objects are near the depth corresponding to the maximum value; if the latter is large, the measured transmission frequency is f4、f6Secondary field induced signal s of time coil output4'、s6', then will | s4'-s4|、|s5'-s5|、|s6'-s6Comparing | the unexploded objects are near the depth corresponding to the maximum value;
the measuring process of the secondary field induction signals in the step 3) and the step 4) is as follows:
a. transmitting the transmitting frequency f and the sampling times n to a receiving controller through an industrial personal computer, and adjusting a capacitor by the receiving controller according to a switch in a frequency adjusting controllable tuning module to enable a circuit to be in a resonance state;
b. sending a collection instruction: sending an excitation and acquisition instruction to a receiving controller through an industrial personal computer, and sending an excitation instruction to a transmitting controller by the receiving controller;
c. emitting a sine wave: the receiving controller sends a synchronous signal to the transmitting controller, the transmitting controller outputs stable voltage through the DC-DC conversion module, and the transmitting controller transmits frequency f and amplitude I to the transmitting coil through the driving circuitTThe sine wave of (1);
d. collecting signals: receiving a primary field signal through a third receiving coil, amplifying the primary field signal through a preamplifier, filtering the primary field signal through a second band-pass filter, carrying out controllable amplification through a second program control amplifier, transmitting the amplified primary field signal to an acquisition card, and then transmitting the amplified primary field signal to an industrial personal computer for storage; the signal acquisition card is used for acquiring signals of a program control amplifier, and the signals are transmitted to an industrial personal computer for storage through a receiving controller;
e. and (3) superposition measurement: and c, repeatedly executing the steps c and d according to the stacking times set in the step a until the stacking is finished.
7. The method of claim 6, wherein the transmitting frequency f and the sampling times n are sent to the receiving controller through the industrial personal computer, and the receiving controller adjusts the capacitance by adjusting a switch in the controllable tuning module according to the frequency so that the circuit is in a resonance state and satisfies the following formula:
the sensitivity is then adjusted according to the following formula:
Uc＝QU
f: transmission frequency, Q: quality factor, C: capacitance value in the access circuit in the controllable tuning module, R: equivalent resistance of the first receiving coil and the second receiving coil, L is equivalent inductance of the first receiving coil and the second receiving coil, Uc: the voltage at the two ends of the capacitor is the output voltage of the two receiving coils, U: the difference between the induced voltages of the two receiving coils.
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