CN102998654A - Method and device of label phase information and based on passive wireless radio frequency recognition - Google Patents
Method and device of label phase information and based on passive wireless radio frequency recognition Download PDFInfo
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- CN102998654A CN102998654A CN2012104835260A CN201210483526A CN102998654A CN 102998654 A CN102998654 A CN 102998654A CN 2012104835260 A CN2012104835260 A CN 2012104835260A CN 201210483526 A CN201210483526 A CN 201210483526A CN 102998654 A CN102998654 A CN 102998654A
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Abstract
The invention relates to the field of pervasive computing and particularly relates to a method and device of label phase information and based on passive wireless radio frequency recognition. A method adopts fine-grit location parameter- phase information based on a physical layer to achieve accurate location of a passive radio frequency identification device (RFID) system and introduce various clustering methods, the optimum clustering method is selected by comparing different conditions to acquire accurate phase value of radio wave of RFID reflection, simultaneously the phase value is processed to reduce phase calculation error and improve location accuracy under the static state and the dynamic state. The method and device is suitable for various application scenes including single antenna, double antennas, multiple antennas and the like, resolves the problem that a single method causes application scene errors in a traditional method and improves location accuracy edgewise.
Description
Technical field
The present invention relates to the general fit calculation field, relate in particular to localization method and device based on passive type wireless radio frequency identification mark phase information.
Background technology
At present, owing to easy, cost is low, be easy to the reasons such as storage, radio frequency identification (RFID, Radio Frequency IDentification) technology has obtained large-scale application in a lot of fields, comprises that indoor positioning, storehouse management, supply chain management, item tracing are traced to the source, access control etc.Rfid system uses radiowave as the medium of transmission of information, in communication and energy transmission, can produce the relevant information of wireless signal, comprise the information such as amplitude, phase place, signal intensity, angle, make it to become the utility system that possesses accurate indoor positioning ability.
With by deep research, for different systems, the wireless signal eigenwert that adopts is different based on the localization method of wireless signal feature.According to the accurate degree of eigenwert, we can be divided into two classifications to existing method, i.e. coarseness eigenwert location and fine granularity eigenwert location.The coarseness eigenwert refers to that those obtain than being easier to, but be subject to easily the eigenwert of external environment factor affecting, received signal strength (Received Signal Strength Indicator for example, RSSI), the angular array of transmitter and receiver, the information such as time of arrival (toa) difference, understand the most intuitively the coarseness eigenwert, we can investigate RSSI information, there are objects moving between Receiver And Transmitter or environment temperature, when Humidity Generator changes, unpredictable variation all can occur in the RSSI value, and the general error of method that therefore adopts the coarseness eigenwert to position all can be very large.The fine granularity eigenwert refers to that those are closer to the information of Physical layer, this category feature value generally is subjected to such environmental effects smaller, but obtain comparatively difficulty, need special hardware device support, (the Phase Information of the phase information in the rfid system for example, PI) and (the Channel State Information of the channel state information in the Wi-Fi network, CSI), CSI utilizes to have orthogonal frequency division multiplexi (Orthogonal Frequency Division Multiplexing, OFDM) status information of each subcarrier in the system of characteristic, the reaction surrounding environment is on the impact of signal, general method is to utilize the Intel5300 network interface card directly to obtain channel shock response result (Channel Impulse Response, CIR), all information that comprise a wireless sinusoidal signal among the CIR/CSI, therefore only the effect of an applicable amplitude parameter is well a lot of than RSSI having aspect the anti-multipath effect, on the other hand, because what CIR/CSI collected is the information of a plurality of frequencies, therefore also can offset part because the error that multipath effect causes according to the difference of frequency.Although CIR/CSI has a lot of advantages, in rfid system, because the problem of communication mechanism, OFDM does not support, therefore improves the bearing accuracy of rfid system and can only introduce phase information.
What the passive type rfid system adopted is the communication modes of retroreflection formula, namely by read write line (R﹠amp; W) send read signal, after label (TAG) charging, reflect radio signals, information in the label is sent back read write line, unique distinction just because of retroreflection formula communication modes, so that read write line and label do not need to carry out the time synchronized (signal all be by the antenna transmission of read write line and reception) of signal, saved communication-cost and energy, guaranteed simultaneously the accuracy of phase information.Wireless signal is to utilize the sinusoidal wave modulation transmissions of carrying out, and general sinusoidal wave signal can will usually be determined with amplitude, frequency and three in phase place.We can represent the state of a sine wave with have intensity vector and the polar coordinates of complex plane, in polar coordinate system, can represent with two components, that X-axis represents is I(In-phase, homophase) component, that Y-axis represents is Q(Quadrature, quadrature) component.The phase differential that 90 degree are arranged between the IQ component.As shown in Figure 1, in IQ figure, the length of a vector represents the amplitude of signal, and the angle of vector and I component is phase place, i.e. θ among Fig. 1.If can obtain the IQ value of the antenna transmission signal of read write line, then can obtain the phase place of signal.The distance of transmitter and receiver can obtain by frequency and the phase calculation of signal.After obtaining phase information, usually can adopt the method for phase differential to position, namely utilize the variation reflection distance of phase place.Comparatively three kinds of phase difference methods commonly used are respectively: time domain Phase difference (Time Domain Phase Difference of Arrival, be called for short TDPDOA), frequency domain Phase difference (Frequency.Domain Phase Difference of Arrival, be called for short FDPDOA) and space phase method of difference (Spatial Domain Phase Difference of Arrival is called for short SDPDOA).These methods directly calculate relative position according to the frequency information of signal.When phase information was accurate, three kinds of above-mentioned methods can both provide accurately range measurements.But, actual measured results as shown in Figure 2, the IQ in the passive type rfid system relatively disperses, therefore its main cause is the interference that is subject to the external environment reflected signal, can cause very large phase error.This is just so that the methods and resultses such as TDPDOA, FDPDOA and SDPDOA are relatively poor, and this is existing methodical first wretched insufficiency.For solving static immobilization result's inaccuracy, there is the researchist to propose to move according to the route of reserving in advance in advance the antenna (ANT) of read write line, because the distance of read write line and target labels is changing in the moving process always, therefore can obtain a series of phase value, reduce the phase error that single measurement causes by data acquisition repeatedly.But the method can only be for the situation of mobile read write line, needs at least three different position measurements, and the position that finally provides is probability distribution, does not generally adapt to for many application.Especially the inaccurate problem of phase place still exists.Therefore existing methodical the second deficiency is data acquisition and calculation of complex under dynamic condition, and precision is also not enough simultaneously.
Summary of the invention
The object of the invention is to propose a kind of localization method and device based on passive type wireless radio frequency identification mark phase information, phase information is obtained inaccurate and error that produce is large, data acquisition and calculation of complex and the not high problem of precision during Kinematic Positioning when solving the radio frequency identification static immobilization.
For reaching this purpose, the present invention by the following technical solutions:
Localization method based on passive type wireless radio frequency identification mark phase information comprises:
A, calculate phase value:
The continuous radiowave of the antenna transmission of read write line is to label, and collecting device gathers the reflected signal of label, sets up the polar coordinates of this reflected signal, polar coordinates comprise X-axis and Y-axis, X-axis represents the homophase I component, and Y-axis represents the quadrature Q component, and homophase I component and quadrature Q component form the IQ data; Adopt clustering algorithm that the IQ data are carried out computing, obtain phase value;
B, calculate the antenna of read write line and the distance of label by the phase value that calculates.
Wherein, adopt clustering algorithm that the IQ data are carried out computing, obtain phase information, comprising:
Wherein a kind of clustering algorithm according in k nearest-neighbors node clustering algorithm of alternative condition selection, k means clustering algorithm, the support vector machine clustering algorithm adopts the clustering algorithm of this selection that the IQ data are carried out computing, obtains phase value;
Wherein, alternative condition comprises: final cluster result is 2-4 classification, and exceptional value is minimum after the cluster, and the phasing degree fluctuation range is minimum after the cluster.
Wherein, the steps A calculated phase values is specially:
A1, preset i=1, the value of reset-to-n, n span 20-50;
The antenna of A2, read write line gathers the i secondary reflection signal of label by the i time continuous radiowave of emission, set up the polar coordinates of this i secondary reflection signal, polar coordinates comprise X-axis and Y-axis, X-axis represents the homophase I component, Y-axis represents the quadrature Q component, and homophase I component and quadrature Q component form the IQ data the i time; Adopt clustering algorithm that the i time IQ data carried out computing, obtain phase value the i time;
A3, judge whether i equals n, if so, continue steps A 4, otherwise i=i+1 continues steps A 2;
A4, n phase value averaged.
Wherein, before described employing clustering algorithm carries out computing to the IQ data, also comprise: remove the abnormity point in the IQ data.
Wherein, described step B calculates the antenna of read write line and the distance of label by the phase value that calculates, and adopts following formula to calculate:
D=n λ+Φ/2 π λ; D is the distance of antenna and the label of read write line, and n is the multiple of wavelength, and λ is the wavelength of continuous radiowave, and wavelength obtains by the frequency computation part of continuous radiowave, and Φ is phase value.
When wherein, described localization method is the localization method of single antenna pattern:
Steps A calculates phase value and is specially, and the sky alignment label of read write line is successively launched the continuous radiowave of two kinds of frequencies, calculates the phase value of two respectively corresponding these two kinds of frequencies;
Step B calculates the antenna of read write line and the distance of label by the phase value that calculates, and adopts following formula to calculate: D=n λ
1+ Φ
1/ 2 π λ
1, D=n λ
2+ Φ
2/ 2 π λ
2, D is the distance of antenna and the label of read write line, n is the multiple of wavelength, λ
1And λ
2For successively launching the wavelength of continuous radiowave, these two wavelength calculate Φ by the twice frequency of the continuous radiowave of priority emission
1And Φ
2It is the phase value of two respectively corresponding these two kinds of frequencies;
When wherein, described localization method is the localization method of double antenna pattern:
Steps A calculates phase value and is specially, and the continuous radiowave of two sky alignment label emission same frequencys of read write line calculates two respectively phase values of two antennas of correspondence;
Step B calculates the antenna of read write line and the distance of label by the phase value that calculates, and adopts following formula to calculate: D
1=n λ+Φ
1/ 2 π λ, D
2=n λ+Φ
2/ 2 π λ, s
2=D
1 2+ D
2 2-2D
1D
2Cos Δ s, D
1And D
2Be respectively the distance of two antennas and label, n is the multiple of wavelength, and λ is the wavelength of continuous radiowave, and the frequency computation part of the continuous radiowave of this wavelength emission obtains, Φ
1And Φ
2Be the phase value of two antennas, s represents the distance of two antennas, and Δ s represents the plane included angle of label to two antenna.
Locating device based on passive type wireless radio frequency identification mark phase information comprises:
Gather computing unit, be used for calculating phase value:
The continuous radiowave of the antenna transmission of read write line is to label, and collecting device gathers the reflected signal of label, sets up the polar coordinates of this reflected signal, polar coordinates comprise X-axis and Y-axis, X-axis represents the homophase I component, and Y-axis represents the quadrature Q component, and homophase I component and quadrature Q component form the IQ data; Adopt clustering algorithm that the IQ data are carried out computing, obtain phase value;
Positioning unit is used for calculating the antenna of read write line and the distance of label by the phase value that calculates.
Wherein, adopt clustering algorithm that the IQ data are carried out computing, obtain phase information, comprising:
Wherein a kind of clustering algorithm according in k nearest-neighbors node clustering algorithm of alternative condition selection, k means clustering algorithm, the support vector machine clustering algorithm adopts the clustering algorithm of this selection that the IQ data are carried out computing, obtains phase value;
Wherein, described alternative condition comprises: final cluster result is 2-4 classification, and exceptional value is minimum after the cluster, and the phasing degree fluctuation range is minimum after the cluster.
Wherein, calculated phase values is specially:
A1, preset i=1, the value of reset-to-n, n span 20-50;
The antenna of A2, read write line gathers the i secondary reflection signal of label by the i time continuous radiowave of emission, set up the polar coordinates of this i secondary reflection signal, polar coordinates comprise X-axis and Y-axis, X-axis represents the homophase I component, Y-axis represents the quadrature Q component, and homophase I component and quadrature Q component form the IQ data the i time; Adopt clustering algorithm that the i time IQ data carried out computing, obtain phase value the i time;
A3, judge whether i equals n, if so, continue steps A 4, otherwise i=i+1 continues steps A 2;
A4, n phase value averaged.
Wherein, before described employing clustering algorithm carries out computing to the IQ data, also comprise: remove the abnormity point in the IQ data.
Wherein, the described antenna and the distance of label that calculates read write line by the phase value that calculates, adopt following formula calculating:
D=n λ+Φ/2 π λ; D is the distance of antenna and the label of read write line, and n is the multiple of wavelength, and λ is the wavelength of continuous radiowave, and wavelength obtains by the frequency computation part of continuous radiowave, and Φ is phase value.
When wherein, described locating device is the locating device of single antenna pattern:
Calculate phase value and be specially, the sky alignment label of read write line is successively launched the continuous radiowave of two kinds of frequencies, calculates the phase value of two respectively corresponding these two kinds of frequencies;
Calculate the antenna of read write line and the distance of label by the phase value that calculates, adopt following formula to calculate: D=n λ
1+ Φ
1/ 2 π λ
1, D=n λ
2+ Φ
2/ 2 π λ
2, D is the distance of antenna and the label of read write line, n is the multiple of wavelength, λ
1And λ
2For successively launching the wavelength of continuous radiowave, these two wavelength calculate Φ by the twice frequency of the continuous radiowave of priority emission
1And Φ
2It is the phase value of two respectively corresponding these two kinds of frequencies;
When wherein, described locating device is the locating device of double antenna pattern:
Calculate phase value and be specially, the continuous radiowave of two sky alignment label emission same frequencys of read write line calculates two respectively phase values of two antennas of correspondence;
Calculate the antenna of read write line and the distance of label by the phase value that calculates, adopt following formula to calculate: D
1=n λ+Φ
1/ 2 π λ, D
2=n λ+Φ
2/ 2 π λ, s
2=D
1 2+ D
2 2-2D
1D
2Cos Δ s, D
1And D
2Be respectively the distance of two antennas and label, n is the multiple of wavelength, and λ is the wavelength of continuous radiowave, and the frequency computation part of the continuous radiowave of this wavelength emission obtains, Φ
1And Φ
2Be the phase value of two antennas, s represents the distance of two antennas, and Δ s represents the plane included angle of label to two antenna.
Beneficial effect of the present invention is: the present invention has adopted fine-grained positional parameter-realize the passive type rfid system is carried out precise positioning based on the phase information of Physical layer, introduce multiple clustering method, select optimum clustering method to obtain the accurate phase information of the reflective radiowave of RFID by more various different situations, simultaneously phase value is processed, reduce the phase calculation error, improve the bearing accuracy under the Static and dynamic condition, the present invention is applicable to single antenna, the plurality of application scenes such as double antenna, solve the error that the application scenarios that only uses single method to cause in the classic method is not inconsistent, improved from the side bearing accuracy.
Description of drawings
Fig. 1 is the phase diagram of single continuous radiowave;
Fig. 2 is a plurality of phase information exemplary plot;
Fig. 3 is measured data IQ error exemplary plot;
Fig. 4 is the continuous radiowave synoptic diagram in the iso standard;
Fig. 5 is read write line and the label communication signal figure of actual measurement;
Fig. 6 is localization method process flow diagram of the present invention;
Fig. 7 is KNN cluster exemplary plot;
Fig. 8 is K-means cluster exemplary plot;
Fig. 9 is SVM cluster exemplary plot;
Figure 10 is single antenna phase place location synoptic diagram;
Figure 11 is double antenna phase place location synoptic diagram;
Figure 12 is many antenna phases location synoptic diagram;
Embodiment
Further specify technical scheme of the present invention below in conjunction with Fig. 1-Figure 12 and by embodiment.
Localization method based on passive type wireless radio frequency identification mark phase information comprises:
A, calculate phase value:
The continuous radiowave of the antenna transmission of read write line is to label, and collecting device gathers the reflected signal of label, sets up the polar coordinates of this reflected signal, polar coordinates comprise X-axis and Y-axis, X-axis represents the homophase I component, and Y-axis represents the quadrature Q component, and homophase I component and quadrature Q component form the IQ data; Adopt clustering algorithm that the IQ data are carried out computing, obtain phase value;
Fig. 1 has described the distribution situation of a continuous radio waveform on phase plane.Wherein A represents amplitude, and the point among the phase plane figure has represented the I component of phase value and the numerical value of Q component.
B, calculate the antenna of read write line and the distance of label by the phase value that calculates.
In the present embodiment, the method that adopts clustering algorithm that selected data are carried out computing is a common practise, also is a common practise by the antenna of phase value calculating read write line and the distance of label.
In the present embodiment, adopt clustering algorithm that the IQ data are carried out computing, obtain phase information, comprising:
Wherein a kind of clustering algorithm according in k nearest-neighbors node clustering algorithm of alternative condition selection, k means clustering algorithm, the support vector machine clustering algorithm adopts the clustering algorithm of this selection that the IQ data are carried out computing, obtains phase value;
Wherein, alternative condition comprises: final cluster result is 2-4 classification, and exceptional value is minimum after the cluster, and the phasing degree fluctuation range is minimum after the cluster.
In the present embodiment, these several alternative conditions have priority, prepreerence is that cluster result is 2-4 classification, next is that exceptional value is minimum after the cluster, that the phasing degree fluctuation range is minimum after the cluster at last, if can select Optimal Clustering according to the condition that priority is high, can consider so the low condition of priority of back.Except these three essential conditions, also has some other condition, such as central point Rational choice after the cluster: the center position that calculates should have continuous relation with the center position that associated location before calculates, if it is too large to jump, then think unreasonable, if continuity is relatively good, then think reasonably.
In the present embodiment, the steps A calculated phase values is specially:
A1, preset i=1, the value of reset-to-n, n span 20-50;
The antenna of A2, read write line gathers the i secondary reflection signal of label by the i time continuous radiowave of emission, set up the polar coordinates of this i secondary reflection signal, polar coordinates comprise X-axis and Y-axis, X-axis represents the homophase I component, Y-axis represents the quadrature Q component, and homophase I component and quadrature Q component form the IQ data the i time; Adopt clustering algorithm that the i time IQ data carried out computing, obtain phase value the i time;
A3, judge whether i equals n, if so, continue steps A 4, otherwise i=i+1 continues steps A 2;
A4, n phase value averaged.
In the present embodiment, to set the parameter of phase information collecting device before the collection reflected signal: frequency, energy, antenna sensitivity, circulation read-write number of times, wherein, frequency is the operating frequency range of passive type radio frequency identification system, should satisfy the frequency requirement of China's regulation: in 840～845MHz and the 920～925MHz scope, energy refers to the energy of the signal that antenna is launched, generally between 15-30dBm, the antenna susceptibility refers to the induction of antenna receiving signal, susceptibility is higher, more can receive weak signal, be set to 10dBm among the present invention, circulation read-write number of times refers to the number of times of read write line and label communication, and the higher phase sample that collects of number of times is more, has generally adopted 20-50 time among the present invention.The consideration that arranges like this be lower than 20 times phase sample quantity very little, might be disturbed by the error sample, if sample collection is too much, energy consumption and call data storage are higher, therefore, select 20-50 time comparatively reasonable, corresponding sample space scope is between 700 to 2000;
In the present embodiment, respectively to n=20, n=30, these three kinds of situations of n=50 are calculated.
Fig. 2 has shown the phase information that obtains in real test environment, be the situation after repeatedly reading among the figure, and reading times is 30 times.
Before the employing clustering algorithm carries out computing to the IQ data, also comprise: remove the abnormity point in the IQ data.
Fig. 4 has illustrated the position that continuous radiowave occurs in iso standard, the process that reads of each label comprises that generally 4 order C order middle CW with several, if therefore think sample more, and can be with repeatedly reading and writing the density that improves sample space.
Fig. 5 has showed once the distribution situation of wireless sine wave in the successful read-write.
In the present embodiment, clustering algorithm adopts the kNN algorithm, and Fig. 7 is that to use after the kNN method under 920MHz frequency distance be 0.9 meter cluster result figure.Ellipse circle among the figure represents the data division after the cluster.The acquisition of phase place need to be calculated all kinds of central points, then with line between the central point, after obtaining all combined result, the result is averaged interpolation.Provide at last phase result.
As another kind of embodiment, Fig. 8 has showed the cluster result of k-means method, the data of comparison diagram 7, and the IQ data are disperseed more, if use the kNN method, then can produce more cluster group, the situation that causes error to increase.Therefore, need to select according to IQ data distribution situation the clustering method of suitable optimization.
As another kind of embodiment, Fig. 9 is the synoptic diagram of SVM clustering method, contrasts front two groups of data, and SVM can return more accurately cluster result, can provide more rational central point simultaneously, so that phase result is more accurate.When but SVM processed such as the data of Fig. 7, advantage was not clearly just.
By relatively can finding out of above-mentioned three kinds of clustering methods, not having a kind of clustering method is to adapt to all distribution situations, must be in optimized selection.
In the present embodiment, step B calculates the antenna of read write line and the distance of label by the phase value that calculates, and adopts following formula to calculate:
D=n λ+Φ/2 π λ; D is the distance of antenna and the label of read write line, and n is the multiple of wavelength, and λ is the wavelength of continuous radiowave, and wavelength obtains by the frequency computation part of continuous radiowave, and Φ is phase value.
When in the present embodiment, described localization method is the localization method of single antenna pattern:
Steps A calculates phase value and is specially, and the sky alignment label of read write line is successively launched the continuous radiowave of two kinds of frequencies, calculates the phase value of two respectively corresponding these two kinds of frequencies;
Step B calculates the antenna of read write line and the distance of label by the phase value that calculates, and adopts following formula to calculate: D=n λ
1+ Φ
1/ 2 π λ
1, D=n λ
2+ Φ
2/ 2 π λ
2, D is the distance of antenna and the label of read write line, n is the multiple of wavelength, λ
1And λ
2For successively launching the wavelength of continuous radiowave, these two wavelength calculate Φ by the twice frequency of the continuous radiowave of priority emission
1And Φ
2It is the phase value of two respectively corresponding these two kinds of frequencies;
Fig. 3 has shown under the single antenna condition, uses the frequency of 920MHz, reads and writes 50 times, and antenna transmission power is 20dBm, and distance is the test result of 60cm.Solid line among the figure is the phase angle that collimation method obtains in the basis, is about 44.3 degree.Two dotted lines have represented error range.
As another kind of embodiment, when described localization method is the localization method of double antenna pattern:
Steps A calculates phase value and is specially, and the continuous radiowave of two sky alignment label emission same frequencys of read write line calculates two respectively phase values of two antennas of correspondence;
Step B calculates the antenna of read write line and the distance of label by the phase value that calculates, and adopts following formula to calculate: D
1=n λ+Φ
1/ 2 π λ, D
2=n λ+Φ
2/ 2 π λ, s
2=D
1 2+ D
2 2-2D
1D
2Cos Δ s, D
1And D
2Be respectively the distance of two antennas and label, n is the multiple of wavelength, and λ is the wavelength of continuous radiowave, and the frequency computation part of the continuous radiowave of this wavelength emission obtains, Φ
1And Φ
2Be the phase value of two antennas, s represents the distance of two antennas, and Δ s represents the plane included angle of label to two antenna.
As shown in figure 11, the quantity of antenna is two, two antennas simultaneously with the label communication, the continuous radiowave of the same frequency that two antenna transmissions go out is received by label, receiving separately the continuous radiowave that tag reflection is returned, because two antennas arrange in advance, between two antennas also is a definite value apart from s therefore, by the triangular relationship between two antennas and the label, can calculate the distance B that two antennas arrive label separately
1And D
2
In the present embodiment, the phase information collecting device is the special collecting device made from the emulator of NI, and the signal of antenna transmission is continuous radiowave, and the working environment of present embodiment is indoor environment.
As another kind of embodiment, as shown in figure 12, the quantity of antenna is 3, utilizes angle, the distance between each antenna of label and each antenna to determine that each antenna is to the distance of label.
Locating device based on passive type wireless radio frequency identification mark phase information comprises:
Gather computing unit, be used for calculating phase value:
The continuous radiowave of the antenna transmission of read write line is to label, and collecting device gathers the reflected signal of label, sets up the polar coordinates of this reflected signal, polar coordinates comprise X-axis and Y-axis, X-axis represents the homophase I component, and Y-axis represents the quadrature Q component, and homophase I component and quadrature Q component form the IQ data; Adopt clustering algorithm that the IQ data are carried out computing, obtain phase value;
Fig. 1 has described the distribution situation of a continuous radio waveform on phase plane.Wherein A represents amplitude, and the point among the phase plane figure has represented the I component of phase value and the numerical value of Q component.
Positioning unit is used for calculating the antenna of read write line and the distance of label by the phase value that calculates.
In the present embodiment, the method that adopts clustering algorithm that selected data are carried out computing is a common practise, also is a common practise by the antenna of phase value calculating read write line and the distance of label.
In the present embodiment, adopt clustering algorithm that the IQ data are carried out computing, obtain phase information, comprising:
Wherein a kind of clustering algorithm according in k nearest-neighbors node clustering algorithm of alternative condition selection, k means clustering algorithm, the support vector machine clustering algorithm adopts the clustering algorithm of this selection that the IQ data are carried out computing, obtains phase value;
Wherein, alternative condition comprises: final cluster result is 2-4 classification, and exceptional value is minimum after the cluster, and the phasing degree fluctuation range is minimum after the cluster.
In the present embodiment, these several alternative conditions have priority, prepreerence is that cluster result is 2-4 classification, next is that exceptional value is minimum after the cluster, that the phasing degree fluctuation range is minimum after the cluster at last, if can select Optimal Clustering according to the condition that priority is high, can consider so the low condition of priority of back.Except these three essential conditions, also has some other condition, such as central point Rational choice after the cluster: the center position that calculates should have continuous relation with the center position that associated location before calculates, if it is too large to jump, then think unreasonable, if continuity is relatively good, then think reasonably.
In the present embodiment, the steps A calculated phase values is specially:
A1, preset i=1, the value of reset-to-n, n span 20-50;
The antenna of A2, read write line gathers the i secondary reflection signal of label by the i time continuous radiowave of emission, set up the polar coordinates of this i secondary reflection signal, polar coordinates comprise X-axis and Y-axis, X-axis represents the homophase I component, Y-axis represents the quadrature Q component, and homophase I component and quadrature Q component form the IQ data the i time; Adopt clustering algorithm that the i time IQ data carried out computing, obtain phase value the i time;
A3, judge whether i equals n, if so, continue steps A 4, otherwise i=i+1 continues steps A 2; A4, n phase value averaged.
In the present embodiment, to set the parameter of phase information collecting device before the collection reflected signal: frequency, energy, antenna sensitivity, circulation read-write number of times, wherein, frequency is the operating frequency range of passive type radio frequency identification system, should satisfy the frequency requirement of China's regulation: in 840～845MHz and the 920～925MHz scope, energy refers to the energy of the signal that antenna is launched, generally between 15-30dBm, the antenna susceptibility refers to the induction of antenna receiving signal, susceptibility is higher, more can receive weak signal, be set to 10dBm among the present invention, circulation read-write number of times refers to the number of times of read write line and label communication, and the higher phase sample that collects of number of times is more, has generally adopted 20-50 time among the present invention.The consideration that arranges like this be lower than 20 times phase sample quantity very little, might be disturbed by the error sample, if sample collection is too much, energy consumption and call data storage are higher, therefore, select 20-50 time comparatively reasonable, corresponding sample space scope is between 700 to 2000;
In the present embodiment, respectively to n=20, n=30, these three kinds of situations of n=50 are calculated.
Fig. 2 has shown the phase information that obtains in real test environment, be the situation after repeatedly reading among the figure, and reading times is 30 times.
Before the employing clustering algorithm carries out computing to the IQ data, also comprise: remove the abnormity point in the IQ data.
Fig. 4 has illustrated the position that continuous radiowave occurs in iso standard, the process that reads of each label comprises that generally 4 order C order middle CW with several, if therefore think sample more, and can be with repeatedly reading and writing the density that improves sample space.
Fig. 5 has showed once the distribution situation of wireless sine wave in the successful read-write.
In the present embodiment, clustering algorithm adopts the kNN algorithm, and Fig. 7 is that to use after the kNN method under 920MHz frequency distance be 0.9 meter cluster result figure.Ellipse circle among the figure represents the data division after the cluster.The acquisition of phase place need to be calculated all kinds of central points, then with line between the central point, after obtaining all combined result, the result is averaged interpolation.Provide at last phase result.
As another kind of embodiment, Fig. 8 has showed the cluster result of k-means method, the data of comparison diagram 7, and the IQ data are disperseed more, if use the kNN method, then can produce more cluster group, the situation that causes error to increase.Therefore, need to select according to IQ data distribution situation the clustering method of suitable optimization.
As another kind of embodiment, Fig. 9 is the synoptic diagram of SVM clustering method, contrasts front two groups of data, and SVM can return more accurately cluster result, can provide more rational central point simultaneously, so that phase result is more accurate.When but SVM processed such as the data of Fig. 7, advantage was not clearly just.
By relatively can finding out of above-mentioned three kinds of clustering methods, not having a kind of clustering method is to adapt to all distribution situations, must be in optimized selection.
In the present embodiment, step B calculates the antenna of read write line and the distance of label by the phase value that calculates, and adopts following formula to calculate:
D=n λ+Φ/2 π λ; D is the distance of antenna and the label of read write line, and n is the multiple of wavelength, and λ is the wavelength of continuous radiowave, and wavelength obtains by the frequency computation part of continuous radiowave, and Φ is phase value.
When in the present embodiment, described locating device is the locating device of single antenna pattern:
Steps A calculates phase value and is specially, and the sky alignment label of read write line is successively launched the continuous radiowave of two kinds of frequencies, calculates the phase value of two respectively corresponding these two kinds of frequencies;
Step B calculates the antenna of read write line and the distance of label by the phase value that calculates, and adopts following formula to calculate: D=n λ
1+ Φ
1/ 2 π λ
1, D=n λ
2+ Φ
2/ 2 π λ
2, D is the distance of antenna and the label of read write line, n is the multiple of wavelength, λ
1And λ
2For successively launching the wavelength of continuous radiowave, these two wavelength calculate Φ by the twice frequency of the continuous radiowave of priority emission
1And Φ
2It is the phase value of two respectively corresponding these two kinds of frequencies;
Fig. 3 has shown under the single antenna condition, uses the frequency of 920MHz, reads and writes 50 times, and antenna transmission power is 20dBm, and distance is the test result of 60cm.Solid line among the figure is the phase angle that collimation method obtains in the basis, is about 44.3 degree.Two dotted lines have represented error range.
As another kind of embodiment, when described locating device is the locating device of double antenna pattern:
Steps A calculates phase value and is specially, and the continuous radiowave of two sky alignment label emission same frequencys of read write line calculates two respectively phase values of two antennas of correspondence;
Step B calculates the antenna of read write line and the distance of label by the phase value that calculates, and adopts following formula to calculate: D
1=n λ+Φ
1/ 2 π λ, D
2=n λ+Φ
2/ 2 π λ, s
2=D
1 2+ D
2 2-2D
1D
2Cos Δ s, D
1And D
2Be respectively the distance of two antennas and label, n is the multiple of wavelength, and λ is the wavelength of continuous radiowave, and the frequency computation part of the continuous radiowave of this wavelength emission obtains, Φ
1And Φ
2Be the phase value of two antennas, s represents the distance of two antennas, and Δ s represents the plane included angle of label to two antenna.
As shown in figure 11, the quantity of antenna is two, two antennas simultaneously with the label communication, the continuous radiowave of the same frequency that two antenna transmissions go out is received by label, receiving separately the continuous radiowave that tag reflection is returned, because two antennas arrange in advance, between two antennas also is a definite value apart from s therefore, by the triangular relationship between two antennas and the label, can calculate the distance B that two antennas arrive label separately
1And D
2
In the present embodiment, the phase information collecting device is the special collecting device made from the emulator of NI, and the signal of antenna transmission is continuous radiowave, and the working environment of present embodiment is indoor environment.
As another kind of embodiment, as shown in figure 12, the quantity of antenna is 3, utilizes angle, the distance between each antenna of label and each antenna to determine that each antenna is to the distance of label.
The above only is the specific embodiment of the present invention, and these are described just in order to explain principle of the present invention, and can not be interpreted as by any way limiting the scope of the invention.Based on explanation herein, those skilled in the art does not need to pay performing creative labour can associate other embodiment of the present invention, and these modes all will fall within protection scope of the present invention.
Claims (14)
1. based on the localization method of passive type wireless radio frequency identification mark phase information, it is characterized in that, comprising:
A, calculate phase value:
The continuous radiowave of the antenna transmission of read write line is to label, and collecting device gathers the reflected signal of label, sets up the polar coordinates of this reflected signal, polar coordinates comprise X-axis and Y-axis, X-axis represents the homophase I component, and Y-axis represents the quadrature Q component, and homophase I component and quadrature Q component form the IQ data; Adopt clustering algorithm that the IQ data are carried out computing, obtain phase value;
B, calculate the antenna of read write line and the distance of label by the phase value that calculates.
2. localization method according to claim 1 is characterized in that, described employing clustering algorithm carries out computing to the IQ data, obtains phase information, comprising:
Wherein a kind of clustering algorithm according in k nearest-neighbors node clustering algorithm of alternative condition selection, k means clustering algorithm, the support vector machine clustering algorithm adopts the clustering algorithm of this selection that the IQ data are carried out computing, obtains phase value;
Wherein, described alternative condition comprises: final cluster result is 2-4 classification, and exceptional value is minimum after the cluster, and the phasing degree fluctuation range is minimum after the cluster.
3. localization method according to claim 1 is characterized in that, described steps A calculated phase values is specially:
A1, preset i=1, the value of reset-to-n, n span 20-50;
The antenna of A2, read write line gathers the i secondary reflection signal of label by the i time continuous radiowave of emission, set up the polar coordinates of this i secondary reflection signal, polar coordinates comprise X-axis and Y-axis, X-axis represents the homophase I component, Y-axis represents the quadrature Q component, and homophase I component and quadrature Q component form the IQ data the i time; Adopt clustering algorithm that the i time IQ data carried out computing, obtain phase value the i time;
A3, judge whether i equals n, if so, continue steps A 4, otherwise i=i+1 continues steps A 2;
A4, n phase value averaged.
4. localization method according to claim 1 is characterized in that, before described employing clustering algorithm carries out computing to the IQ data, also comprises: remove the abnormity point in the IQ data.
5. localization method according to claim 1 is characterized in that:
Described step B calculates the antenna of read write line and the distance of label by the phase value that calculates, and adopts following formula to calculate:
D=n λ+Φ/2 π λ; D is the distance of antenna and the label of read write line, and n is the multiple of wavelength, and λ is the wavelength of continuous radiowave, and wavelength obtains by the frequency computation part of continuous radiowave, and Φ is phase value.
6. localization method according to claim 1 is characterized in that:
When described localization method is the localization method of single antenna pattern:
Steps A calculates phase value and is specially, and read write line is successively launched the continuous radiowave of two kinds of frequencies to label, calculates the phase value of two respectively corresponding these two kinds of frequencies;
Step B calculates the distance of read write line and label by the phase value that calculates, adopts following formula calculating: D=n λ
1+ Φ
1/ 2 π λ
1, D=n λ
2+ Φ
2/ 2 π λ
2, D is the distance of antenna and the label of read write line, n is the multiple of wavelength, λ
1And λ
2For successively launching the wavelength of continuous radiowave, these two wavelength calculate Φ by the twice frequency of the continuous radiowave of priority emission
1And Φ
2It is the phase value of two respectively corresponding these two kinds of frequencies.
7. localization method according to claim 1 is characterized in that:
When described localization method is the localization method of double antenna pattern:
Steps A calculates phase value and is specially, and the continuous radiowave of two sky alignment label emission same frequencys of read write line calculates two respectively phase values of two antennas of correspondence;
Step B calculates the distance of read write line and label by the phase value that calculates, adopts following formula calculating: D
1=n λ+Φ
1/ 2 π λ, D
2=n λ+Φ
2/ 2 π λ, s
2=D
1 2+ D
2 2-2D
1D
2Cos Δ s, D
1And D
2Be respectively the distance of two antennas and label, n is the multiple of wavelength, and λ is the wavelength of continuous radiowave, and the frequency computation part of the continuous radiowave of this wavelength emission obtains, Φ
1And Φ
2Be the phase value of two antennas, s represents the distance of two antennas, and Δ s represents the plane included angle of label to two antenna.
8. based on the locating device of passive type wireless radio frequency identification mark phase information, it is characterized in that, comprising:
Gather computing unit, be used for calculating phase value:
The continuous radiowave of the antenna transmission of read write line is to label, and collecting device gathers the reflected signal of label, sets up the polar coordinates of this reflected signal, polar coordinates comprise X-axis and Y-axis, X-axis represents the homophase I component, and Y-axis represents the quadrature Q component, and homophase I component and quadrature Q component form the IQ data; Adopt clustering algorithm that the IQ data are carried out computing, obtain phase value;
Positioning unit is used for calculating the antenna of read write line and the distance of label by the phase value that calculates.
9. locating device according to claim 8 is characterized in that, described employing clustering algorithm carries out computing to the IQ data, obtains phase information, comprising:
Wherein a kind of clustering algorithm according in k nearest-neighbors node clustering algorithm of alternative condition selection, k means clustering algorithm, the support vector machine clustering algorithm adopts the clustering algorithm of this selection that the IQ data are carried out computing, obtains phase value;
Wherein, described alternative condition comprises: final cluster result is 2-4 classification, and exceptional value is minimum after the cluster, and the phasing degree fluctuation range is minimum after the cluster.
10. locating device according to claim 8 is characterized in that, described calculated phase values is specially:
A1, preset i=1, the value of reset-to-n, n span 20-50;
The antenna of A2, read write line gathers the i secondary reflection signal of label by the i time continuous radiowave of emission, set up the polar coordinates of this i secondary reflection signal, polar coordinates comprise X-axis and Y-axis, X-axis represents the homophase I component, Y-axis represents the quadrature Q component, and homophase I component and quadrature Q component form the IQ data the i time; Adopt clustering algorithm that the i time IQ data carried out computing, obtain phase value the i time;
A3, judge whether i equals n, if so, continue steps A 4, otherwise i=i+1 continues steps A 2;
A4, n phase value averaged.
11. locating device according to claim 8 is characterized in that, before described employing clustering algorithm carries out computing to the IQ data, also comprises: remove the abnormity point in the IQ data.
12. locating device according to claim 8 is characterized in that:
The described antenna and the distance of label that calculates read write line by the phase value that calculates, adopt following formula calculating:
D=n λ+Φ/2 π λ; D is the distance of antenna and the label of read write line, and n is the multiple of wavelength, and λ is the wavelength of continuous radiowave, and wavelength obtains by the frequency computation part of continuous radiowave, and Φ is phase value.
13. locating device according to claim 8 is characterized in that:
When described locating device is the locating device of single antenna pattern:
Calculate phase value and be specially, the sky alignment label of read write line is successively launched the continuous radiowave of two kinds of frequencies, calculates the phase value of two respectively corresponding these two kinds of frequencies;
Calculate the antenna of read write line and the distance of label by the phase value that calculates, adopt following formula to calculate: D=n λ
1+ Φ
1/ 2 π λ
1, D=n λ
2+ Φ
2/ 2 π λ
2, D is the distance of antenna and the label of read write line, n is the multiple of wavelength, λ
1And λ
2For successively launching the wavelength of continuous radiowave, these two wavelength calculate Φ by the twice frequency of the continuous radiowave of priority emission
1And Φ
2It is the phase value of two respectively corresponding these two kinds of frequencies.
14. locating device according to claim 8 is characterized in that:
When described locating device is the locating device of double antenna pattern:
Calculate phase value and be specially, the continuous radiowave of two sky alignment label emission same frequencys of read write line calculates two respectively phase values of two antennas of correspondence;
Calculate the antenna of read write line and the distance of label by the phase value that calculates, adopt following formula to calculate: D
1=n λ+Φ
1/ 2 π λ, D
2=n λ+Φ
2/ 2 π λ, s
2=D
1 2+ D
2 2-2D
1D
2Cos Δ s, D
1And D
2Be respectively the distance of two antennas and label, n is the multiple of wavelength, and λ is the wavelength of continuous radiowave, and the frequency computation part of the continuous radiowave of this wavelength emission obtains, Φ
1And Φ
2Be the phase value of two antennas, s represents the distance of two antennas, and Δ s represents the plane included angle of label to two antenna.
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