CN101315349A - Automatic balancing technology for metal foreign body detection - Google Patents
Automatic balancing technology for metal foreign body detection Download PDFInfo
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- CN101315349A CN101315349A CNA2008100406607A CN200810040660A CN101315349A CN 101315349 A CN101315349 A CN 101315349A CN A2008100406607 A CNA2008100406607 A CN A2008100406607A CN 200810040660 A CN200810040660 A CN 200810040660A CN 101315349 A CN101315349 A CN 101315349A
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Abstract
The invention relates to an automatic balancing technique for metal foreign matter detection, in particular to a metal foreign matter detection automatic balancing technique which can carry out automatic balancing adjustment as long as the power is on. The automatic balancing technique solves the problem that a metal foreign matter detector has low detection sensitivity and poor stability due to certain change in original static balancing state, and makes up the defects of difficulty in automatic balancing and no wide application in the prior art.
Description
Technical field
The present invention relates to the automatic balancing technology that a kind of metallic foreign body detects, particularly relate to a kind of start and promptly carry out the automatic balancing technology that the metallic foreign body of Automatic Balance Regulation detects.
Background technology
The metallic foreign body machines has become more and more important key equipment in the industrial trade production runes such as food, chemical industry, building materials and plastics.For guaranteeing the pure of product or raw material, protection personal safety or product quality are protected key equipment safety, stop the production safety accident or the cost of overhaul, all need the metal detection machine to detect and whether contain metallic impurity in the material.
The little change detection technique in magnetic field that balanced type metal detection machine is used in the balance alternating magnetic field detects whether contain metallic impurity in the non-metallic material.Facts have proved, based on the metal detection facility of this know-why have highly sensitive, antijamming capability strong, metal and nonmetal differentiation is effective, different metals can be differentiated, be easy to remarkable advantage such as production.After the influence that be subjected to stress deformation but its fatal shortcoming is exactly its detecting sensor, expand with heat and contract with cold etc. can not be avoided natural cause causes its original static equilibrium state that certain variation takes place, initial stage Key Quality Indicator such as detection sensitivity reduces, noise signal is big, bad stability may occur and descend, and may make that equipment completely loses detection sensitivity after further changing.
The method of the assurance metal machines detection sensitivity that existing technology is taked has: (1) is manufactured as far as possible and sensor construction to be made sturdy, adopts tackifier such as epoxy resin to fix, fill between interior outer chamber, reduces as far as possible to change; (2) sensor carries out stress relief before dispatching from the factory; (3) employing girth surplus method, metal are inserted method, the position is adjusted method mechanical type method and carried out balance adjustment; (4) the bridge-type receiving circuit also adopts potentiometer to regulate.
(1) of above method, (2) can not eliminate or avoid detecting sensor original static equilibrium state that certain variation takes place for reducing the method that changes.(3) plants usually after equipment dispatches from the factory, under client's suitable environment, carry out, very difficulty operates, and must just can finish by the professional and technical personnel of production plant, so only under forced situation, just can adopt, this method need spend great amount of manpower and material resources on the one hand, on the other hand when the distance of client and manufacturer far, or even will be difficult all the more during country variant; What is more, and can only there be ubiquity in each adjusting at a certain concrete object, and the equipment that makes does not have extensive applicability, safeguards also quite difficulty.The degree of regulation of (4) kind method is difficult to control, and the effect of adjusting also directly has influence on the detection effect of equipment, and technology is difficult to hold.
For developing numerous advantages of balanced type metal detection technology, abandon its deadly defect simultaneously, improve the performance of balanced type metal detection machine, reduce the O﹠M cost, adding the Automatic Balance Regulation function is exactly technological core content of the present invention.
Summary of the invention
The purpose of this invention is to provide the automatic balancing technology that a kind of metallic foreign body detects, the automatic balancing technology that the metallic foreign body that just provides a kind of start promptly to carry out Automatic Balance Regulation detects.The invention solves the metallic foreign body machines because of the problem of the low and poor stability of detection sensitivity after certain variation takes place the original static equilibrium state, remedied the deficiency that prior art is difficult to self-poise, does not have broad applicability.
The automatic balancing technology that a kind of metallic foreign body of the present invention detects is the automatic balancing technology that the metallic foreign body detection of Automatic Balance Regulation is promptly carried out in a kind of start, may further comprise the steps:
1) the controller control exciting signal source of being made up of DSP+ARM produces sinusoidal excitation signal;
2) pumping signal produces alternating magnetic field;
3) receiving sensor induction alternating magnetic field;
4) the differential output signal of receiving sensor is to mixer;
5) proportional amplifier carries out the ratio amplification to the signal of mixer;
6) differential wave of equilibrium state extraction unit Comparative Examples amplification is separated mediation filtering;
7) become digital signal behind the signal process A/D converter that previous step obtains and be input to the controller of forming by DSP+ARM;
8) through after the Digital Signal Analysis and Processing of DSP, the Control and Feedback signal synthesizer generates feedback signal;
9) feedback signal feeds back to mixer;
10) signal of mixer receiving feedback signals and receiving sensor and mixing;
11) mixed signal output;
12) if the isolated value of mixed signal output exceeds preset range, then circulate the 5th) step～the 11) step, up to the isolated value of mixed signal output in preset range.Concrete preset range comes field adjustable to obtain according to the linear working range of adjustment time, testing circuit and the noise of finally using the machines of this detection technique.
As optimized technical scheme:
The automatic balancing technology that aforesaid a kind of metallic foreign body detects, wherein, described exciting signal source adopts the DDS chip.
The automatic balancing technology that aforesaid a kind of metallic foreign body detects, wherein, the frequency of described sinusoidal excitation signal is 20～900kHz.
The automatic balancing technology that aforesaid a kind of metallic foreign body detects, wherein, the algorithm of FIR filtering and arc tangent conversion is adopted in the Digital Signal Analysis and Processing of described DSP.
The automatic balancing technology that aforesaid a kind of metallic foreign body detects, wherein, described feedback signal and balance received signal are with frequency, homophase and amplitude and received signal fixed ratio.
The automatic balancing technology that aforesaid a kind of metallic foreign body detects, wherein, the signal of described mixer is proportional to the equilibrium state signal.
The automatic balancing technology that aforesaid a kind of metallic foreign body detects, wherein, described receiving sensor is a differential generator.
The automatic balancing technology that a kind of metallic foreign body of the present invention detects is the automatic balancing technology that the metallic foreign body detection of Automatic Balance Regulation is promptly carried out in a kind of start.The detecting sensor structure of balanced type metal detection machine is as shown in Figure 2: the centre is a transmitting coil, and both sides are receiving coil.Receiving coil is symmetrically distributed in the transmitting coil both sides, the differential connection of two receiving coils.
The sine alternating magnetic field signal of transmitting coil emission fixed frequency
X(t)＝Acos(2πft)........................................(1.1)
On receiving coil, sense constant amplitude with identical frequency ac voltage signal.The differential connection of two receiving coils, under the perfect condition, the output signal amplitude of receiving coil is not zero when surveyed area has external metal or influence of magnetic field.But in fact because existence such as mismachining tolerances, material error, this signal amplitude is a uncertain value that depends on factor such as numerous errors.For guaranteeing detection sensitivity, often needing this signal is carried out enlargement factor is that 1K～10K amplifies.Signal after the amplification is exactly the original signal that judges whether to contain metal when detecting.
R(t)＝(a(t)+a)cos((2πft+θ+θ(t))....................(1.2)
Generally can carry out synchronous demodulation, extract and only comprise metal signal (signal of metal modulated magnetic field) and white noise signal this signal.
Facts have proved, as static amplitude a because expand with heat and contract with cold, the influence of factor such as stress deformation, can progressively change.The signal to noise ratio (S/N ratio) of detection signal obviously descends when amplitude surpasses 500mv, stability and detection sensitivity variation.When a surpasses 2000mv, may operate as normal, false alarm will be considerably beyond acceptable scope.
Technology of the present invention is to add the Automatic Balance Regulation function in detection line.Realize automatic tracking balance adjusting by Automatic Balance Regulation feedback system based on DSP (digital signalprocessor) and DDS (direct digital synthesis) Digital Control.
As shown in Figure 3, be the circuit realization theory diagram of the automatic balancing technology of a kind of metallic foreign body detection of the present invention.The differential received signal of static receiving coil is:
R(t)＝a*cos((2πft+θ)..................................(1.3)
The purpose of Automatic Balance Regulation is the amplitude of the signal under the static state to be adjusted to minimum, and theoretical optimum condition is 0.
Under the open loop situations, proportional amplifier 3 is output as:
S3(t)＝a*k*cos((2πft+θ)..............................(1.4)
The output of information source DDS4 and DDS5 is respectively:
S4(t)＝cos(2πft)........................................(1.5)
S5(t)＝sin(2πft)..........................................(1.6)
Output behind multiplier 8 and 9 is respectively:
S8(t)＝a*cos((2πft+θ)*cos(2πft)...............(1.7)
S9(t)＝a*cos((2πft+θ)*sin(2πft)................(1.8)
Low- pass filter 12 and 13 is output as:
S12(t)＝-a/2*cos(θ).......................................(1.9)
S13(t)＝a/2*sin(θ)........................................(1.10)
Above S12 (t), the signal of S13 (t) reads in DSP after the A/D sampling, after device removal interference of FIR worry ripple and dynamic change, obtain the amplitude and the phase place of initial balance signal.Because the initial balance signal of received signal is and transmits with sinusoidal signal frequently that frequency is therefore fixed, and depends on the frequency that transmits.So essential information of determining to have arrived the initial balance signal of amplitude and phase place.
The amplitude of initial balance signal is carried out projection on the sinusoidal signal together frequently in standard quadrature unit, obtain two quadrature components, component value is exported through D/A converter.
The standard carrier sinusoidal signal that the output signal of D/A and DDS generate multiplies each other respectively at 10 and 11 multipliers, and output signal is exactly the feedback regulation signal:
S10(t)＝-a/2*cos((2πft)cos(θ)..........................(1.11)
S11(t)＝a/2*sin(2πft)*sin(θ)..........................(1.12)
The signal of S10 and S11 exports proportional amplifier S6 to, obtains the following signal S6 that is used for from motion tracking static balancing signal after gain is adjusted:
S6＝a*cos((2πft+θ)
R(T)-S6(t)＝0。
This tracing process is only carried out the time marquis of device power-up, therefore can be not influential to Dynamic Signal (comprising the metal useful signal).
The invention has the beneficial effects as follows:
The automatic balancing technology that a kind of metallic foreign body of the present invention detects solves balanced type metal detection machine because of the change difficult problem of back detection sensitivity, stability decreases of detecting sensor self equilibrium state, improves the stability and the adaptive capacity to environment that detect.
Description of drawings
Fig. 1 is the theory diagram of the automatic balancing technology of a kind of metallic foreign body detection of the present invention
Fig. 2 is the sensor construction synoptic diagram
Fig. 3 is that the circuit of the automatic balancing technology of a kind of metallic foreign body detection of the present invention is realized theory diagram
Wherein 1 is that differential receiving sensor 2 is that signal mixer 3 is proportional amplifiers
The 4th, DDS signal and to grow up to be a useful person 5 are DDS signals and to grow up to be a useful person 6 are proportional amplifiers
The 7th, exciting signal source 8 is multipliers (detuner) the 9th, multiplier (detuner)
The 10th, modulator (multiplier) the 11st, modulator (multiplier) the 12nd, low-pass filter
The 13rd, low-pass filter 14 is that A/D converter 15 is A/D converters
The 16th, D/A converter 17 is that D/A converter 18 is DSP digital signal processors
Embodiment
Below in conjunction with embodiment, further set forth the present invention.Should be understood that these embodiment only to be used to the present invention is described and be not used in and limit the scope of the invention.Should be understood that in addition those skilled in the art can make various changes or modifications the present invention after the content of having read the present invention's instruction, these equivalent form of values fall within the application's appended claims institute restricted portion equally.
As shown in Figure 1, it is the theory diagram of the automatic balancing technology of a kind of metallic foreign body detection of the present invention, the automatic balancing technology that a kind of metallic foreign body of the present invention detects is the automatic balancing technology that the metallic foreign body detection of Automatic Balance Regulation is promptly carried out in a kind of start, may further comprise the steps:
1) the controller control exciting signal source of being made up of DSP+ARM produces sinusoidal excitation signal;
2) pumping signal produces alternating magnetic field;
3) receiving sensor induction alternating magnetic field;
4) the differential output signal of receiving sensor is to mixer;
5) proportional amplifier carries out the ratio amplification to the signal of mixer;
6) differential wave of equilibrium state extraction unit Comparative Examples amplification is separated mediation filtering;
7) become digital signal behind the signal process A/D converter that previous step obtains and be input to the controller of forming by DSP+ARM;
8) through after the Digital Signal Analysis and Processing of DSP, the Control and Feedback signal synthesizer generates feedback signal;
9) feedback signal feeds back to mixer;
10) signal of mixer receiving feedback signals and receiving sensor and mixing;
11) mixed signal output;
12) if the isolated value of mixed signal output exceeds preset range, then circulate the 5th) step～the 11) step, up to the isolated value of mixed signal output in preset range.Concrete preset range comes field adjustable to obtain according to the linear working range of adjustment time, testing circuit and the noise of finally using the machines of this detection technique, makes a detection sensitivity and stability scope in normal condition.
Wherein, described exciting signal source adopts the DDS chip, and the frequency of described sinusoidal excitation signal is 20～900kHz.
The automatic balancing technology that aforesaid a kind of metallic foreign body detects, wherein, the algorithm of FIR filtering and arc tangent conversion is adopted in the Digital Signal Analysis and Processing of described DSP, described feedback signal and balance received signal are with frequency, homophase and amplitude and received signal fixed ratio, the signal of described mixer is proportional to the equilibrium state signal, and described receiving sensor is a differential generator.
As shown in Figure 3, be the circuit realization theory diagram of the automatic balancing technology of a kind of metallic foreign body detection of the present invention.The differential received signal of static receiving coil is:
R(t)＝a*cos((2πft+θ)..................................(1.3)
The purpose of Automatic Balance Regulation is the amplitude of the signal under the static state to be adjusted to minimum, and theoretical optimum condition is 0.
Under the open loop situations, proportional amplifier 3 is output as:
S3(t)＝a*k*cos((2πft+θ)..............................(1.4)
The output of information source DDS4 and DDS5 is respectively:
S4(t)＝cos(2πft).........................................(1.5)
S5(t)＝sin(2πft)..........................................(1.6)
Output behind multiplier 8 and 9 is respectively:
S8(t)＝a*cos((2πft+θ)*cos(2πft)...............(1.7)
S9(t)＝a*cos((2πft+θ)*sin(2πft)................(1.8)
Low- pass filter 12 and 13 is output as:
S12(t)＝-a/2*cos(θ).......................................(1.9)
S13(t)＝a/2*sin(θ)........................................(1.10)
Above S12 (t), the signal of S13 (t) reads in DSP after the A/D sampling, after device removal interference of FIR worry ripple and dynamic change, obtain the amplitude and the phase place of initial balance signal.Because the initial balance signal of received signal is and transmits with sinusoidal signal frequently that frequency is therefore fixed, and depends on the frequency that transmits.So essential information of determining to have arrived the initial balance signal of amplitude and phase place.
The amplitude of initial balance signal is carried out projection on the sinusoidal signal together frequently in standard quadrature unit, obtain two quadrature components, component value is exported through D/A converter.
The standard carrier sinusoidal signal that the output signal of D/A and DDS generate multiplies each other respectively at 10 and 11 multipliers, and output signal is exactly the feedback regulation signal:
S10(t)＝-a/2*cos((2πft)cos(θ)..........................(1.11)
S11(t)＝a/2*sin(2πft)*sin(θ)..........................(1.12)
The signal of S10 and S11 exports proportional amplifier S6 to, obtains the following signal S6 that is used for from motion tracking static balancing signal after gain is adjusted:
S6＝a*cos((2πft+θ)
R(T)-S6(t)＝0。
This tracing process is only carried out the time marquis of device power-up, therefore can be not influential to Dynamic Signal (comprising the metal useful signal).
Claims (7)
1. the automatic balancing technology that detects of a metallic foreign body is characterized in that may further comprise the steps:
1) the controller control exciting signal source of being made up of DSP+ARM produces sinusoidal excitation signal;
2) pumping signal produces alternating magnetic field;
3) receiving sensor induction alternating magnetic field;
4) the differential output signal of receiving sensor is to mixer;
5) proportional amplifier carries out the ratio amplification to the signal of mixer;
6) differential wave of equilibrium state extraction unit Comparative Examples amplification is separated mediation filtering;
7) become digital signal behind the signal process A/D converter that previous step obtains and be input to the controller of forming by DSP+ARM;
8) through after the Digital Signal Analysis and Processing of DSP, the Control and Feedback signal synthesizer generates feedback signal;
9) feedback signal feeds back to mixer;
10) signal of mixer receiving feedback signals and receiving sensor and mixing;
11) mixed signal output;
12) if the isolated value of mixed signal output exceeds preset range, then circulate the 5th) step～the 11) step, up to the isolated value of mixed signal output in preset range.
2. the automatic balancing technology that a kind of metallic foreign body as claimed in claim 1 detects is characterized in that described exciting signal source adopts the DDS chip.
3. the automatic balancing technology that a kind of metallic foreign body as claimed in claim 1 detects is characterized in that the frequency of described sinusoidal excitation signal is 20～900kHz.
4. the automatic balancing technology that a kind of metallic foreign body as claimed in claim 1 detects is characterized in that the algorithm of FIR filtering and arc tangent conversion is adopted in the Digital Signal Analysis and Processing of described DSP.
5. the automatic balancing technology that a kind of metallic foreign body as claimed in claim 1 detects is characterized in that described feedback signal and balance received signal are with frequency, homophase and amplitude and received signal fixed ratio.
6. the automatic balancing technology that a kind of metallic foreign body as claimed in claim 1 detects is characterized in that the signal of described mixer is proportional to the equilibrium state signal.
7. the automatic balancing technology that a kind of metallic foreign body as claimed in claim 1 detects is characterized in that described receiving sensor is a differential generator.
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| CNA2008100406607A CN101315349A (en) | 2008-07-17 | 2008-07-17 | Automatic balancing technology for metal foreign body detection |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102565185A (en) * | 2010-12-27 | 2012-07-11 | 上海太易检测技术有限公司 | Automatic phase tracking information processing method and device for use in metal foreign matter detector |
| CN102681019A (en) * | 2011-03-09 | 2012-09-19 | 苏州太易检测设备有限公司 | Automatic balance information processing method and device of metallic foreign body detecting machine |
| CN103123334A (en) * | 2011-11-20 | 2013-05-29 | 常州先进制造技术研究所 | High-precision microparticle metal detection DDS (Direct Digital Synthesizer) circuit |
-
2008
- 2008-07-17 CN CNA2008100406607A patent/CN101315349A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102565185A (en) * | 2010-12-27 | 2012-07-11 | 上海太易检测技术有限公司 | Automatic phase tracking information processing method and device for use in metal foreign matter detector |
| 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 |
| CN102681019A (en) * | 2011-03-09 | 2012-09-19 | 苏州太易检测设备有限公司 | Automatic balance information processing method and device of metallic foreign body detecting machine |
| CN102681019B (en) * | 2011-03-09 | 2014-08-13 | 苏州太易检测设备有限公司 | Automatic balance information processing method and device of metallic foreign body detecting machine |
| CN103123334A (en) * | 2011-11-20 | 2013-05-29 | 常州先进制造技术研究所 | High-precision microparticle metal detection DDS (Direct Digital Synthesizer) circuit |
| CN103123334B (en) * | 2011-11-20 | 2016-11-23 | 常州先进制造技术研究所 | A kind of high accuracy molecule metal detection DDS circuit |
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Open date: 20081203 |