CN100439904C - Intelligent metal detector - Google Patents
Intelligent metal detector Download PDFInfo
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- CN100439904C CN100439904C CNB2004100675728A CN200410067572A CN100439904C CN 100439904 C CN100439904 C CN 100439904C CN B2004100675728 A CNB2004100675728 A CN B2004100675728A CN 200410067572 A CN200410067572 A CN 200410067572A CN 100439904 C CN100439904 C CN 100439904C
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Abstract
The present invention relates to an intelligent metal detector which belongs to the technical field of lossless electromagnetic detection. A digital signal processor generates a sinusoidal wave through a direct digital synthesis chip; after the sinusoidal wave passes through a transmitting circuit and an amplifying circuit, the sinusoidal wave is conveyed to a transmitting coil; a receiving coil conveys signals to a receiving circuit, and the signals are respectively conveyed to two multipliers in two paths; the digital signal processor generates two paths of signals through the two direct digital synthesis chips, and the two paths of signals are respectively conveyed to the two multipliers; the two multipliers obtain two paths of separated signals through two low pass filters; the two paths of signals are conveyed to an A/D convertor; through A/D conversion, obtained data is introduced into the digital signal processor; the digital signal processor analyzes and judges the collected data; a man-machine dialogue system is composed of a single chip computer, and the man-machine dialogue system and the digital signal processor form serial communication. The present invention adopts DSP and the direct digital synthesis technique to replace an analogue circuit. Simultaneously, the independent single chip computer is adopted to complete the man-machine dialogue function, the stability is enhanced, and the defect of the analogue circuit is fundamentally changed.
Description
Technical field
The present invention relates to the detector in a kind of nondestructive electromagnetic detection technique field, specifically, relate to a kind of intelligent metal detector.
Background technology
Metal detector is different according to ultimate principle and detection line, is broadly divided into beat type, auto-excited induction-type, consuming type (power absorption formula) and balanced type.Adopt balanced type can obtain, can detect the following metallic particles of 1mm than higher sensitivity.Metal detector in the market adopts mimic channel to realize basically.Adopting the advantage of mimic channel is that circuit is simple, realizes easily.Shortcoming is simulation system anti-interference, poor stability.Difficulty of parameter tuning.Adopt digital technology then can overcome the problem that analog line exists.The digital technology scheme that is used for metal detector has two kinds: a kind of is to adopt simulation circuit structure substantially, just output valve is delivered in the microprocessor by A/D converter at output and is judged, has increased the man-machine conversation function simultaneously.The another kind of Direct Digital synthetic method that adopts produces modulated sinusoid, and phase place that can the offset of sinusoidal ripple is controlled.This method has not only improved the resolution of phase place and the stability of system, and provides convenience for parameters self-tuning.Metal detector in the market mostly is made of mimic channel, and the shortcoming of mimic channel is regulated difficulty, poor stability exactly.Though some metal detector adopts microprocessor, only is used for output and man-machine conversation, does not fundamentally change the defective of mimic channel.
Find by prior art documents, the United States Patent (USP) patent No. 5,786,696, denomination of invention: METAL DETECTOR FOR IDENTIFYING TARGET ELECTRICAL CHARACTERISTICS, DEPTHAND SIZE, (" can survey the metal detector of the metal object classification and the degree of depth and size ").This metal detector adopts DSP to handle the signal of gathering, and single-chip microcomputer is handled peripheral interface and liquid crystal display, adopts the fast Flourier method to handle the classification that obtains object.The sine wave that this patent is used does not produce by DSP and digital synthesis chip, therefore can not move and control phase place, can not be used for the adjustment and the self study of parameter.
Summary of the invention
The objective of the invention is to overcome deficiency of the prior art, a kind of intelligent metal detector has been proposed, make it adopt DSP and Direct Digital synthetic technology to substitute mimic channel, adopt independently single-chip microcomputer to finish the man-machine conversation function simultaneously, improve stability, fundamentally changed the defective of mimic channel.
The present invention is achieved by the following technical solutions, the present invention includes: digital signal processor (DSP), interactive system, three Direct Digital synthesis chips, two multipliers, two low-pass filters, electricity erasable memorizer (E
2PROM), transmitting coil, radiating circuit, receiving coil, receiving circuit.
Digital signal processor through delivering to transmitting coil behind the radiating circuit amplifying circuit, is set up the electromagnetic field of an alternation by the standard sine wave of a 50～400kHz of Direct Digital synthesis chip generation.Receiving coil is symmetrically distributed in the both sides of transmitting coil.Receiving coil passes to receiving circuit with signal, is divided into two-way and delivers to two multipliers respectively.Digital signal processor by the first Direct Digital synthesis chip and the second Direct Digital synthesis chip produce two-way mutually the orthogonal signal of 90 ° of phasic differences deliver to two multipliers respectively.Two multipliers through two low-pass filters obtain that two-way separates sensitive and to iron to the signal of stainless steel sensitivity, this two paths of signals is sent into A/D converter, import digital signal processor into through the data that A/D is converted to, digital signal processor carries out analysis and judgement to the data of gathering and whether has metallic particles.Interactive system is made of single-chip microcomputer, with the digital signal processor serial communication.
Interactive system that the present invention is made of single-chip microcomputer and dot matrix lcd, electricity erasable memorizer (E
2PROM), optoelectronic switch and keyboard cooperate, and is used for man-machine conversation and parameter modification.Adopt the max485 serial ports to connect between single-chip microcomputer and the DSP, DSP is a slave computer, is responsible for carrying out single-chip microcomputer and transmits the order of getting off.Single-chip microcomputer is a host computer, is responsible for realizing man-machine conversation, specifically by keyboard, optoelectronic switch and dot matrix lcd, electricity erasable memorizer (E
2PROM) realize.Dot matrix lcd is that dot matrix is used for the Chinese display menu.Optoelectronic switch 17 is used to show the size of output signal and report to the police.Keyboard is used for the parameter input.Electricity erasable memorizer (E
2PROM) be used for stored parameter.The LED and the hummer of usefulness of being used to report to the police is connected to single-chip microcomputer, is subjected to Single-chip Controlling.The realization of self-learning function: for improving the intelligent degree of metal detector, the present invention has added the parameters self-tuning function.After starting self-learning function, metal detector can be adjusted phase place automatically according to the signal of gathering, and suppresses the product effect.
According to Theory of Electromagnetic Field, the alternation that transmitting coil produces produces the induction electromotive force of a same frequency, anti-phase, constant amplitude respectively in the receiving coil of two differential connections, and both disappear mutually and promptly form receiving balance.Metal in alternating magnetic field will be because eddy effect (relevant with conductivity) or magnetic effect (relevant with magnetic permeability) will produce complementary field one by one, and the magnetic line of force that destroys primary field distributes, and this complementary field is called secondary field again.The non-ferromagnetic metal conductivity is bigger, and it comprises paramagnet (as manganese, titanium) and diamagnet (as gold, silver), can think to conduct electricity non-magnetic material, mainly produces eddy effect, and magnetic effect can be ignored; Ferromagnetic metal (as iron, nickel, cobalt) magnetoconductivity is very big, and conductivity is also bigger, can think promptly to conduct electricity and magnetic conduction substance, mainly produces magnetic effect, and eddy effect is arranged again simultaneously.The secondary field that metal target produced can make the size of electric current in the receiving coil and phase place change, therefore can be by the signal Processing that receives first coil is judged whether to exist metal.
The present invention adopts phase detection method, and specific implementation is by two multipliers.Its ultimate principle is: suppose that receiving coil is output as Uo=Asin (ω t-φ), two orthogonal sinusoidal waves that are input as same frequency of modulation are respectively Us=Bsin ω t and Uc=Bsin (ω t+90 °).
Be respectively by output behind the multiplier:
Ur＝Uo*Us＝Asin(ωt-φ)*Bsinωt＝-AB/2[cos(2ωt-φ)-co8φ]
Ux＝Uo*Uc＝Asin(ωt-φ)*Bsin(ωt+90)＝-AB/2[sin(2ωt-φ)-sinφ]
Through after the low-pass filter, radio-frequency component is filtered, and is output as:
U
R＝AB/2cosφ
U
X＝AB/2sinφ
Because B is the may command constant, so U
RAnd U
XSize be decided by phase and amplitude A.Studies show that amplitude is relevant with the size of object, and the kind of object is relevant with phase place.When will forming during along with conveyer belt, object passes through U
R, U
XCurve to line speed.By kind that can judgment object to the detection of the amplitude of this curve and direction.In the present invention, the big I of phase is set by numeral, just can signal that treat metal object is outstanding for different examined object as long as change the size of φ, thus detect metal object.Basic functional principle of the present invention that Here it is.
Special feature of the present invention is to adopt single-chip microcomputer, digital signal processor (DSP) and Direct Digital synthetic technology (DDS) to produce frequency, a phase place all can pass through digital regulated sine wave.
The present invention has self-learning function, makes this metal detector have intellectuality.The method of study is with U
RAnd U
XWaveform acquisition in DSP, then by to two slightly the analyses of waveforms draw the direction and the size of phase shifts.The two-way waveform that studies show that ferromagnetic material is in same direction and then represents it is the characteristic of irony (fe), and what waveform presented when being reverse is Stainless Steel (sus) characteristic.As long as initial phase can be set between fe and the sus, then can adjust the size of initial phase φ according to the size and Orientation of acquired signal, make product by the time two paths of signals be in below the threshold values, satisfy the requirement that the product effect suppresses, thereby metal object separated with the weakly conducting object.After self study was finished, the parameter of setting just can satisfy the purpose that product separates with metal object, when product passes through, output signal is in below the threshold values, when the product that is mixed with metal passed through, output signal was in more than the threshold values, and machine just can come out golden room object detection like this.
The present invention adopts single-chip microcomputer, digital signal processor (DSP) and Direct Digital synthetic technology (DDS) to produce frequency, a phase place all can pass through digital regulated sine wave, this structure not only makes parameter be provided with conveniently, and can access the sine wave that frequency and phase linearity change, and the sine wave that adopts analogy method to obtain is very difficult on frequency and phase change, and the change of frequency and phase place presents nonlinearities change.DSP is not only as signal Processing among the present invention, but also is used to produce the control of the sine wave and the I/0 mouth of modulation; Direction and size according to signal adopt the method for following the tracks of to obtain the classification of object, and adjust phase place in view of the above automatically, suppress the product effect.The present invention has self-learning function, makes this metal detector have intellectuality.The present invention adopts DSP, single-chip microcomputer upper and lower computer structure in addition, and single-chip microcomputer is responsible for man-machine conversation, and DSP is responsible for producing signal and A/D conversion and signal Processing.The function and the extensibility of system have greatly been strengthened.The present invention not only makes the stability of metal detector and reliability improve, and has greatly improved the intelligent level of metal detector, has greatly improved the ratio of performance to price of metal detector, thereby makes this metal detector have the stronger market competitiveness.The present invention is widely used in food, medicine, weaving, clothes, toy etc., the metallic particles of sneaking into wherein can be detected and eliminating, guarantees food and personal safety.
Description of drawings
Fig. 1 structured flowchart of the present invention
Fig. 2 DDS ultimate principle block diagram
Fig. 3 single-chip microcomputer, digital signal processor, Direct Digital synthesis chip connect block diagram
Fig. 4 workflow diagram of the present invention
Fig. 5 is a self study main flow chart of the present invention
Fig. 6 is self study data acquisition of the present invention and processing synoptic diagram
Embodiment
As Figure 1-3, the present invention includes: digital signal processor 1, interactive system 2, Direct Digital synthesis chip 3,4,5, multiplier 6,7, low-pass filter 8 and 9, transmitting coil 11, radiating circuit 12, receiving coil 13, receiving circuit 14.Digital signal processor 1 through delivering to transmitting coil 11 behind radiating circuit 12 amplifying circuits, is set up the electromagnetic field of an alternation by the standard sine wave of a 50～400kHz of Direct Digital synthesis chip 3 generations.Receiving coil 13 is symmetrically distributed in the both sides of transmitting coil.Receiving coil 13 passes to receiving circuit 14 with signal, is divided into two-way and delivers to multiplier 6 and multiplier 7 respectively.Digital signal processor 1 by Direct Digital synthesis chip 4 and Direct Digital synthesis chip 5 produce two-way mutually the orthogonal signal of 90 ° of phasic differences deliver to multiplier 7 and multiplier 6 respectively.Multiplier 6 and multiplier 7 through low-pass filters 8 and 9 obtain that two-way separates to the iron sensitivity with to the signal of stainless steel sensitivity, this two paths of signals is sent into A/D converter, import digital signal processor into through the data that A/D is converted to, digital signal processor carries out analysis and judgement to the data of gathering and whether has metallic particles.Interactive system 2 is made of single-chip microcomputer, with digital signal processor 1 serial communication.
The interactive system 2 that the present invention is made of single-chip microcomputer is connected with dot matrix lcd 16, electricity erasable memorizer (E
2PROM) 10, LED and hummer 15, optoelectronic switch 17 and the keyboard 18 of the usefulness that is used to report to the police cooperate, and is used for man-machine conversation and parameter modification.Adopt the max485 serial ports to connect between single-chip microcomputer 2 and the DSP1, DSP1 is a slave computer, is responsible for carrying out single-chip microcomputer and transmits the order of getting off.Single-chip microcomputer is a host computer, is responsible for realizing man-machine conversation, specifically by keyboard 18, optoelectronic switch 17 and dot lcd 16, electricity erasable memorizer (E
2PROM) 10 realize.Liquid crystal 16 is used for the Chinese display menu for dot matrix.Optoelectronic switch 17 is used to show the size of output signal.The LED and the hummer 15 of usefulness of being used to report to the police is subjected to Single-chip Controlling, when output signal LED and hummer 15 actions during greater than setting signal, sounds a buzzer.Keyboard is used for the parameter input.Electricity erasable memorizer (E
2PROM) 10 are used for stored parameter DSP1 and export needed sine wave and A/D conversion and signal Processing according to frequency of setting and phase place.The realization of self-learning function: for improving the intelligent degree of metal detector, the present invention has added the parameters self-tuning function.After starting self-learning function, metal detector can be adjusted phase place automatically according to the signal of gathering, and suppresses the product effect.
As shown in Figure 4, the metal detector switch opens, after machine powers on, system will carry out initialized work, through the adjustment of a long time, enter the choice phase then, preestablish one group of parameter in metal detector, can directly move.Also can enter parameter modification, reset sensitivity, phase place, store this parameter into E then
2Among the PROM, so that call next time.
As shown in Figure 5, at first setting the study number of times is M, still can not meet the demands after M time and just abandon.After starting the self study program, counter, travelling belt, AD converter are opened, and product flows into, and digital display circuit begins image data, according to the size and Orientation of gathering that calculates curve.Judge the direction and the size of phase change next time according to the size and Orientation of curve then.Carry out so repeatedly, until signal is reduced to below the threshold values.If learning success, then the parameter that study is obtained stores E into
2Among the PROM.
As shown in Figure 6, reverse in the same way according to the Wave data judgement that sampling each time obtains, determine the increase and decrease direction.Judge whether to change the parameter setting according to amplitude again, the phasing degree of each increase and decrease is previous 1/2, after new parameter is provided with change effectively, whether judges amplitude again＜below the 1.0V, if then expression is set successfully, and preserve existing parameter setting.Initial conditions are set at:
SENSA=SENSB=32.4 (ratio), threshold value=2V.
Claims (5)
1, a kind of intelligent metal detector, comprise: interactive system (2), first multiplier (6), second multiplier (7), first low-pass filter (8), second low-pass filter (9), transmitting coil (11), radiating circuit (12), receiving coil (13) and receiving circuit (14), it is characterized in that, also comprise: digital signal processor (1), the first Direct Digital synthesis chip (3), the second Direct Digital synthesis chip (4) and the 3rd Direct Digital synthesis chip (5), wherein: digital signal processor (1) produces sinusoidal wave by the first Direct Digital synthesis chip (3), through delivering to transmitting coil (11) behind radiating circuit (12) amplifying circuit, receiving coil (13) passes to receiving circuit (14) with signal, be divided into two-way and deliver to first multiplier (6) and second multiplier (7) respectively, digital signal processor (1) produces two paths of signals by the second Direct Digital synthesis chip (4) and the 3rd Direct Digital synthesis chip (5) and delivers to second multiplier (7) and first multiplier (6) respectively, first multiplier (6), second multiplier (7) is through first low-pass filter (8), second low-pass filter (9) obtains the signal that two-way separates, this two paths of signals is sent into A/D converter, import digital signal processor (1) into through the data that A/D is converted to, digital signal processor (1) carries out analysis and judgement to the data of gathering, interactive system (2) is made of single-chip microcomputer, with digital signal processor (1) serial communication.
2, intelligent metal detector according to claim 1, it is characterized in that, the interactive system (2) that is made of single-chip microcomputer also is connected with electricity erasable memorizer (10), the LED and the hummer (15) of usefulness are used to report to the police, dot matrix lcd (16), optoelectronic switch (17) and keyboard (18), adopt the max485 serial ports to connect between single-chip microcomputer (2) and the digital signal processor (1), digital signal processor (1) is a slave computer, be responsible for carrying out the order that single-chip microcomputer (2) transmits, single-chip microcomputer (2) is a host computer, be responsible for realizing man-machine conversation, concrete by keyboard (18), optoelectronic switch (17) and dot lcd (16), electricity erasable memorizer (10) is realized, the LED and the hummer (15) of usefulness of being used to report to the police is subjected to Single-chip Controlling, LCD (16) is a dot matrix, optoelectronic switch (17) is used to show the size of output signal, electricity erasable memorizer (10) is used for stored parameter, and digital signal processor (1) is exported needed sine wave and A/D conversion and signal Processing according to frequency of setting and phase place.
3, intelligent metal detector according to claim 1 is characterized in that, receiving coil (13) is symmetrically distributed in the both sides of transmitting coil (11).
4, intelligent metal detector according to claim 1, it is characterized in that, described digital signal processor (1) produces sinusoidal wave by the first Direct Digital synthesis chip (3), the sine wave that is produced is: the standard sine wave of 50～400kHz, through delivering to transmitting coil (11) behind radiating circuit (12) amplifying circuit, set up the electromagnetic field of an alternation.
5, intelligent metal detector according to claim 1, it is characterized in that, digital signal processor (1) by the second Direct Digital synthesis chip (4) and the 3rd Direct Digital synthesis chip (5) produce two-way mutually the orthogonal signal of 90 ° of phasic differences deliver to first multiplier (6) and second multiplier (7) respectively.
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| CNB2004100675728A CN100439904C (en) | 2004-10-28 | 2004-10-28 | Intelligent metal detector |
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| CNB2004100675728A CN100439904C (en) | 2004-10-28 | 2004-10-28 | Intelligent metal detector |
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| CN100439904C true CN100439904C (en) | 2008-12-03 |
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| CN1865952B (en) * | 2005-05-18 | 2010-10-13 | 上海高晶金属探测设备有限公司 | Intelligent storable industrial metal detector |
| CN101327484B (en) * | 2008-04-17 | 2011-09-07 | 常州煜明电子有限公司 | Metallic separator |
| CN103180760B (en) * | 2010-10-07 | 2016-10-26 | 梅特勒-托利多安全线有限公司 | For operating method and the metal detecting system of metal detecting system |
| CN102565185B (en) * | 2010-12-27 | 2015-03-04 | 上海太易检测技术有限公司 | Automatic phase tracking information processing method for using in metal foreign matter detector |
| CN102207487B (en) * | 2011-01-06 | 2012-11-28 | 大连交通大学 | Quick metal material characteristic identifier system of |
| CN102266854B (en) * | 2011-05-13 | 2013-07-24 | 上海高晶检测科技股份有限公司 | Foreign material repulsion control system and control method thereof |
| CN103149594B (en) * | 2013-01-15 | 2015-11-25 | 同济大学 | A kind of metal detection door with parameter pre-setting function automatically |
| CN103149595B (en) * | 2013-03-04 | 2015-07-08 | 上海景灵检测技术有限公司 | Metal foreign body detector |
| CN103278856B (en) * | 2013-06-07 | 2015-09-02 | 国家电网公司 | Underground cable comprehensive detection system |
| CN105223620A (en) * | 2015-01-06 | 2016-01-06 | 金陵科技学院 | A kind of SCM Based metal object probe positioners |
| CN106199736A (en) * | 2016-08-24 | 2016-12-07 | 上海芝研检测技术有限公司 | A kind of workflow of metal detection machine suppression product effect |
| CN111103624A (en) * | 2019-12-18 | 2020-05-05 | 广东第二师范学院 | Online metal detection system based on internet technology |
| CN111521202A (en) * | 2020-05-08 | 2020-08-11 | 量一度(苏州)传感科技有限公司 | Adjustable distance inductive sensor |
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