CN102466793B - Method for accurately positioning electronic tag - Google Patents

Abstract

The invention discloses a method for accurately positioning an electronic tag, comprising steps of: firstly establishing an antenna array of a radio-frequency signal detector; positioning the electronic tag to a two-dimensional plane from a three-dimensional space through a four-point positioning method; and then in combination with a trigonometric function algorithm, positioning the electronic tag to a 1/2 two-dimensional plane from the two-dimensional plane, further positioning the electronic tag to a 1/4 two-dimensional plane from the 1/2 two-dimensional plane, at last accurately positioning the electronic tag at the 1/4 two-dimensional plane. The positioning algorithm provided by the invention has the advantages of simple operation principle, small calculation amount, good instantaneity, and high positioning accuracy, and can be applied to a situation in which the electronic tag is accurately positioned.

Description

A kind of electronic tag accurate positioning method

Technical field

The present invention relates to the passive electronic label field of locating technology, be specifically related to a kind of using radio frequency recognizing technique (RFID) combining wireless radio wave propagation characteristics, realize the accurate location of electronic tag by location algorithm.

Background technology

REID (RFID) is a kind of automatic identification technology that begins to rise the nineties in 20th century, it utilizes radiofrequency signal to pass through Space Coupling (alternating magnetic field or electromagnetic field) and realizes contactless information transmission, and the information of passing through to transmit reaches identifying purpose.The frequency of rfid system mainly contains 125kHz, 13.56MHz, 900MHz, 2.45GHz, 5.8GHz.It is if system about 13.56MHz that the research of present domestic RFID mainly concentrates on frequency of operation, then studies less in the ultrahigh frequency field.A typical rfid system mainly contains read write line, electronic tag, terminal three parts composition.The basic functional principle of RFID technology: after electronic tag enters magnetic field, receive the radiofrequency signal that read write line sends, the energy that relies on induction current to obtain sends out the self information that is stored in the chip; After read write line reading information and the decoding, deliver to terminal and carry out the relevant data processing.

The electronic tag of rfid system is comprised of miniature antenna, special chip and specific outer package.Each label has unique electronic code, is attached on the article to be identified, is the real data carrier of radio-frequency recognition system.According to the difference of its power supply mode, can be divided into three kinds of active label, half passive label and passive labels.Battery is housed in the active label; Half passive label does not have internal battery, and the electromagnetic power rectification of adopting read write line to launch obtains direct current energy and comes maintenance work; Passive label does not need direct current energy, is specially adapted to the environment that uses for a long time or be difficult to safeguard.Electronic tag can be applicable to that logistics and supplies management, the manufacturing and assembling, aviation luggage are processed, mail/fast freight parcel processing, document tracking/library management, animal identification sign, motion timing, access control/electronic entrance ticket, road automatic charging, false proof etc.According to the needs of some occasion practical applications, electronic tag need to be realized accurately location at three dimensions sometimes.

Summary of the invention

Technical matters to be solved by this invention provides a kind of electronic tag accurate positioning method, utilize REID (RFID), method by four point positioning is carried out, and this algorithm has the advantages that principle of operation is simple, calculated amount is little, real-time is good, bearing accuracy is high.

The present invention solves the problems of the technologies described above the technical scheme that adopts: a kind of electronic tag accurate positioning method is characterized in that may further comprise the steps successively:

1) sets up the aerial array of radiofrequency signal detection instrument at three dimensions, top A, the B of four antennas, C, D are positioned at respectively on x axle, y axle and the z axle, wherein C is positioned at the y axle, D is positioned at the z axle, and A, B are positioned on the x axle, and the distance of A, B, C, D and initial point is respectively Ao=Bo=m λ, Co=n λ, Do=k λ, λ are the radio frequency wavelength, and m, n, k are the integer greater than 1;

2) transmission frequency is the radiofrequency signal of f, electronic tag M to be positioned can loopback same frequency f self signal, according to signal time and the velocity of wave that antenna reception arrives, measure the distance of M and antenna A, B, C, D, according to the distance of MA and MB M is positioned simultaneously the round o ' on a parallel and yz plane;

3) on circle o ' plane, set up three-dimensional coordinate xy ' z ' take o ' as initial point, in conjunction with the trigonometric function algorithm, calculate the distance of M and o ', o, the angle of Mo ' and y ' axle is positioned at M one side of z ' axle;

4) at last the distance of M and the D distance with M and o is compared, the M point is positioned: the distance of M and D illustrates M point and D point homonymy less than the distance of M and o; The distance of M and D illustrates M point and D point heteropleural greater than the distance of M and o.

Described step 3) specific algorithm process is:

1) according to MA, the MB and the AB distance that record, in Δ MAB,

Obtain ∠ MBA, such Mo '=MBsin ∠ MBA, o ' B=MB * cos ∠ MBA;

2) cross the parallel lines that some C makes the x axle, hand over y ' axle in a C ', CC '=oo '=o ' B-0B is because Δ MCc ' ⊥ y ' o ' z ' can get

And o ' c '=oC can utilize the triangle cosine law equally:

Try to achieve ∠ Mo ' c ', be the angle of Mo ' and y ' axle.

At last, the rectangular coordinate system that x axle, y axle, z axle form in the described three dimensions adopts polar coordinate system to replace.Aerial array is applied on the hand-held positioning equipment, by installing the laser guide device additional at hand-held positioning equipment front end, can search out more rapidly target in conjunction with this algorithm again.

Compared with prior art, the invention has the advantages that: by the constructing antennas array, a kind of 4 point location algorithms have been proposed, at first with electronic tag from the three-dimensional fix to the two dimensional surface, and then navigate to 1/2 two dimensional surface from two dimensional surface, and relocate 1/4 two dimensional surface from 1/2 two dimensional surface, accurately determine the position what 1/4 two dimensional surface was realized electronic tag at last.This algorithm has the advantages that principle of operation is simple, calculated amount is little, real-time is good, bearing accuracy is high.According to the needs of designed system, the M dot position information that this algorithm can be obtained is converted under rectangular coordinate system or the polar coordinate system by triangle relation and uses.This algorithm can be applicable to hand-held positioning equipment, by installing the guide pieces such as laser additional at hand-held positioning equipment front end, can search out more rapidly target in conjunction with this algorithm again.

Description of drawings

Fig. 1 is the three-dimensional distribution map on the antenna top of radio frequency detection instrument of the present invention;

Fig. 2 determines M codomain synoptic diagram by A, B point;

Fig. 3 (a) is to determine M and M ' synoptic diagram by the C point (b);

Fig. 4 (a) is by the D point M accurately to be located synoptic diagram (b).

Embodiment

Embodiment is described in further detail the present invention below in conjunction with accompanying drawing.

A kind of electronic tag Precision Orientation Algorithm, concrete steps are:

1, sets up the aerial array of radiofrequency signal detection instrument at three dimensions

As shown in Figure 1, in three dimensions, suppose that there is a passive electronic label at any point M place.A radiofrequency signal detection instrument is arranged in effective scope of detection.The antenna of this instrument is array antenna, and each antenna top is according to A, B, 4 arrangements of C, D in 1 among the figure, wherein, AO=OB=m λ, OC=n λ, OD=k λ, λ is that radio frequency wavelength and AO, OB, OC, OD are definite value, and the M point is hypothesis electronic tag position.

2, three-dimensional fix is determined the M codomain to two dimensional surface

The radiofrequency signal detection instrument is at t ₀When constantly being the radiofrequency signal of f to peripheral transmission frequency, corresponding electronic tag can be the f self information to detection instrument loopback carrier frequency.Because detection instrument has four antennas, at this moment, can be respectively at t _A, t _B, t _C, t _DConstantly receive respectively 1 echoed signal, according to s=1/2 * c * Δ t, s is the point-to-point transmission one way distance, and c is velocity of EM-waves, and Δ t is the reciprocal time of electromagnetic wave, then can obtain,

$s_{\mathrm{MA}}=\frac{1}{2}\×c\×{\mathrm{\Δt}}_{\mathrm{MA}}$

$s_{\mathrm{MB}}=\frac{1}{2}\×c\×{\mathrm{\Δt}}_{\mathrm{MB}}$

$s_{\mathrm{MC}}=\frac{1}{2}\×c\×{\mathrm{\Δt}}_{\mathrm{MC}}$

$s_{\mathrm{MD}}=\frac{1}{2}\×c\×{\mathrm{\Δt}}_{\mathrm{MD}}$

At three dimensions, satisfy MA, MB distance and be respectively s _MA, s _MBThe M codomain be a round o ' who is parallel to the yz two dimensional surface, such as Fig. 2, as can be seen from Figure 2, a M point that only navigates to according to MA, MB is a many-valued situation.

3, two dimensional surface navigates to 1/2 two dimensional surface

In order to obtain unique M point, also need increase constraint condition, to solve the many-valued problem of M.Such as Fig. 3 (a), Δ MAB ⊥ y ' o ' z ', again known s _MA, s _MBAnd s _AB, be beneficial to the cosine law, can try to achieve ∠ MBA,

$\cos \∠\mathrm{MBA}=\frac{{\mathrm{MB}}^2+{\mathrm{AB}}^2-{\mathrm{MA}}^2}{2\×\mathrm{MB}\×\mathrm{AB}},$

Mo '=MB * sin ∠ MBA again, o ' B=MB * cos ∠ MBA can get oo '=o ' B-oB, and oo '=Cc ', thereby obtain Cc '.Equally, Δ MCc ' ⊥ y ' o ' z ' can get thus,

For Δ Mo ' c ', Mo ', Mc ' all obtain, and o ' c '=oC can utilize the triangle cosine law to try to achieve ∠ Mo ' c ' equally,

$\∠M{o}^{\′}{c}^{\′}=\frac{{M{c}^{\′}}^2+{o^{\′}{c}^{\′}}^2-{M{c}^{\′}}^2}{2\×{\mathrm{Mo}}^{\′}\×o^{\′}{c}^{\′}},$

If α=∠ Mo ' c ', α are the angle that the M point begins to rotate from y ' positive axis.Among Fig. 3 (a), the M point obtains for being rotated counterclockwise α.According to symmetry, satisfy equally above-mentioned computation process at M ' point.M ' rotates clockwise α by y ' positive axis to obtain, such as Fig. 3 (b).At this moment, the M of gained point is still not unique, but has been limited to the Left half-plane of z ' axle, also needs to continue to process.

4,1/2 two dimensional surface navigates to 1/4 two dimensional surface

Shown in Fig. 4 (a), MD is apart from s _MDBy measuring.In Δ Mo ' o, Mo ', o ' o all obtain, Δ Mo ' o ⊥ y ' o ' z ', and Δ Mo ' o is right-angle triangle, then

Distance between note Mo is s _MoBy Fig. 4 (b) as can be known, at M and a M ' side, s _MDIncrease along with the increase at α angle.Can get thus, if s _MD＜s _MoThen the M point is D point homonymy (being the z positive axis among Fig. 4 (b)), otherwise the M point is D point heteropleural (being the negative semiaxis of z among Fig. 4 (b)).By above calculating, determined at last unique electronic tag signal launching site M on 1/4y ' o ' z ' plane.

Like this by the constructing antennas array, a kind of 4 point location algorithms have been proposed, realized the accurate location of electronic tag, the method has the advantages that principle of operation is simple, calculated amount is little, real-time is good, bearing accuracy is high, according to the needs of designed system, the M dot position information that this method can be obtained is converted under rectangular coordinate system or the polar coordinate system by triangle relation and uses.This method can be applicable to hand-held positioning equipment, by installing the guide pieces such as laser additional at hand-held positioning equipment front end, can search out more rapidly target in conjunction with this method again.

Claims (3)

1. electronic tag accurate positioning method is characterized in that may further comprise the steps successively:

1) sets up the aerial array of radiofrequency signal detection instrument at three dimensions, top A, the B of four antennas, C, D are positioned at respectively on x axle, y axle and the z axle, wherein C is positioned at the y axle, D is positioned at the z axle, and A, B are positioned on the x axle, and the distance of A, B, C, D and initial point is respectively Ao=Bo=m λ, Co=n λ, Do=k λ, λ are the radio frequency wavelength, and m, n, k are the integer greater than 1;

2) transmission frequency is the radiofrequency signal of f, electronic tag M to be positioned can loopback same frequency f self signal, according to signal time and the velocity of wave that antenna reception arrives, measure the distance of M and antenna A, B, C, D, according to the distance of MA and MB M is positioned simultaneously the round o ' on a parallel and yz plane;

3) on circle o ' plane, set up three-dimensional coordinate xy ' z ' take o ' as initial point, in conjunction with the trigonometric function algorithm, calculate the distance of M and o ', o, the angle of Mo ' and y ' axle is positioned at M one side of z ' axle;

In order to obtain unique M point, increase constraint condition, to solve the many-valued problem of M, constraint condition is Δ MAB ⊥ y ' o ' z ';

4) at last the distance of M and the D distance with M and o is compared, the M point is positioned: the distance of M and D illustrates M point and D point homonymy less than the distance of M and o; The distance of M and D illustrates M point and D point heteropleural greater than the distance of M and o.

2. electronic tag accurate positioning method according to claim 1 is characterized in that described step 3) the specific algorithm process be:

1) according to MA, the MB and the AB distance that record, in Δ MAB, Obtain ∠ MBA, such Mo '=MBsin ∠ MBA, o ' B=MB * cos ∠ MBA;

2) cross the parallel lines that some C makes the x axle, hand over y ' axle in a C ', CC '=oo '=o ' B-OB is because Δ MCc ' ⊥ y ' o ' z ' can get And o ' c '=oC can utilize the triangle cosine law equally:

Try to achieve ∠ Mo ' c ', be the angle of Mo ' and y ' axle.

3. electronic tag accurate positioning method according to claim 1 and 2 is characterized in that the rectangular coordinate system that x axle in the described three dimensions, y axle, z axle form adopts polar coordinate system to replace.

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