CN104360313A - Multiple-LED based light source locating method - Google Patents

Abstract

The invention discloses a multiple-LED based light source locating method, and relates to the application field of LED optical communication and indoor locating. The multiple-LED based light source locating method includes by a receiving terminal, receiving optical signals sent by a plurality of reference LEDs simultaneously to acquire estimated distances between the LEDs and the receiving terminal, and correcting the estimated distances to acquire corrected distances; selecting three LEDs with the nearest corrected distances to perform triangulation location, and initially estimating estimated coordinates of the receiving terminal; calculating weights according to the corrected distances between the LEDs and the receiving terminal; selecting coordinate points corresponding to optimal maximum likelihood estimation from adjacent coordinates; judging whether or not the coordinates corresponding to the optimal maximum likelihood estimation are located in the selected range of the adjacent points, and if yes, determining the adjacent coordinates to be the optimal estimated coordinates of the receiving terminal. The multiple-LED based light source locating method has the advantages that influences of measured deviations are weakened, location estimation errors are reduced, and measurement robustness is improved.

Description

A kind of method of locating based on many LED light sources

Technical field

The present invention relates to LED light communication and indoor positioning application, specifically relate to a kind of method of locating based on many LED light sources.

Background technology

LED (Lighting Emitting Diode, light emitting diode) is called as forth generation lighting source or green light source, also can be applicable in radio optical communication system while providing room lighting.LED-based indoor positioning is an application direction had a high potential, and LED location usually adopts and positions based on RSS (Received Signal Power, received signal power) and triangle method of geometry.Because LED communication system has light wireless communication, under horizon communication (LOS) condition and transmission and reception angular alignment situation, Received signal strength luminous power formula meets:

$\mathrm{Pr}\left(d\right)=\mathrm{Pr}\left(d_0\right)+10*n*\lg \left(\frac{d}{d_0}\right)+X$

Wherein d is the distance between transmitting node to receiving node, and n is path loss index, relevant with the environment of surrounding, represents that power increases the speed of decay with distance; X to be mean value be 0 Gaussian distributed random variable, d ₀for the reference distance between transmitting node to receiving node, usually get 1 meter; Pr (d ₀) represent at reference distance to be d ₀time the power that records.According to above-mentioned formula, luminous power linearly reduces with the increase of communication distance, and the available logarithmic curve of relation of received power and distance represents, after determining this corresponding relation, record received signal power can determine transmit and receive between distance.

According to triangle geometrical principle, receiving end measures the distance of the known independent source in three positions, can locate the position drawing receiving end.Because received optical power can be subject to the brightness of light source, the scattering of flashlight and the impact of the factor such as reflection, light transmission and reception angle usually, the fluctuation of received optical power and measuring error can affect estimated distance and last positioning result.When detection range is near, small distance change causes significant received power to change, and therefore usually selects nearest, that received power is maximum three points of detection range to carry out three-point fix.But time only based on three-point fix, the error measuring power directly can affect solving of equation; If when certain in nearest 3 is a bit unavailable, then the reference point selected non-optimal, also cannot accurate estimated distance.

Summary of the invention

For the defect existed in prior art, the object of the present invention is to provide a kind of method of locating based on many LED light sources, reduce the impact of measured deviation, reduce the error of position estimation.

For reaching above object, the present invention takes a kind of method of locating based on many LED light sources, based on receiving end and multiple use LED as the transmitting terminal of light source, comprises step:

S1. receiving end receives from multiple visible light signal sent with reference to LED simultaneously; Receiving end detects the transmission signal power of each LED, draws the estimated distance of each LED to receiving end according to power-distance homologous thread;

S2. there is the estimated distance of emission angle and acceptance angle to revise to LED, obtain corrected range; Three LED choosing corrected range nearest carry out triangle polyester fibre, the estimation coordinate of receiving end according to a preliminary estimate;

S3. according to the corrected range calculating weight of each LED to receiving end;

S4. multiple coordinate points of estimation nearby coordinates are chosen, if estimation coordinate is (x _e, y _e, z _e), neighbouring coordinate points is (x _j, y _k, z _e), neighbouring coordinate points meets x _j=x _e+ j*step, y _k=y _e+ k*step (-L≤j, k≤L), wherein L is positive integer, and step is the step-length of skew, is brought into respectively by the coordinate of multiple described coordinate points

$S={\mathrm{\Σ}}_{i=1}^N{\mathrm{\α}}_i(\sqrt{{(x_e-x_i)}^2+{(y_e-y_i)}^2+{(z_e-z_i)}^2}-d_{\mathrm{ci}}),$ Calculate corresponding S value, choose the coordinate points that minimum S value is corresponding, wherein N is the number with reference to LED, α _ifor weight, d _cibe the corrected range of i-th LED to receiving end;

S5. judge coordinate corresponding to minimum S value whether nearby coordinate points choose interval inside, if not, enter S6; If so, S7 is entered;

S6. using coordinate corresponding for this minimum S value as new estimation coordinate, jump to S4;

S7. the coordinate that this minimum S value is corresponding is optimum receiving end estimation coordinate.

On the basis of technique scheme, described transmitting terminal, multiple LED is cellular being arranged in same plane in field of illumination.

On the basis of technique scheme, described power-distance homologous thread is obtained by actual measurement or experience.

On the basis of technique scheme, in described S2, the computing formula of corrected range is wherein d _eifor the estimated distance in S1, d _cifor the corrected range of estimated distance, when multiple LED be honeycomb arrangement at same plane time, M is LED minimum spacing, and h is the vertical range of receiving end to LED place plane, and n is correction factor.

On the basis of technique scheme, in described S2, assuming that three LED coordinate X=(x that corrected range is nearest _i, y _i, z _i), (i=1,2,3), the estimation coordinate of receiving end is (x _e, y _e, z _e), then have

${(x_e-x_1)}^2+{(y_e-y_1)}^2+{(z_e-z_1)}^2=d_{c1}^2$

${(x_e-x_2)}^2+{(y_e-y_2)}^2+{(z_e-z_2)}^2=d_{c2}^2$

${(x_e-x_3)}^2+{(y_e-y_3)}^2+{(z_e-z_3)}^2=d_{c3}^2$

Work as z ₁=z ₂=z ₃time, obtain AX=B, wherein

$A=\left[\begin{array}{cc}{x}_2-x_1& y_2-y_1\\ x_3-x_1& y_3-y_1\end{array}\right],B=\left[\begin{array}{c}(d_{c1}^2-d_{c2}^2+x_2^2+y_2^2-x_1^2-y_1^2)/2\\ (d_{c1}^2-d_{c3}^2+x_3^2+y_3^2-x_1^2-y_1^2)/2\end{array}\right]$

Then $X=\left[\begin{array}{c}{x}_e\\ y_e\end{array}\right]={\left(A^{T}A\right)}^{-1}{A}^{T}B.$

On the basis of technique scheme, in described S3, pass through calculate weight α _i, wherein, meet d _cifor corrected range, d _ckrepresent d _c1~ d _cNin any one.

Beneficial effect of the present invention is: by the comprehensive estimation of the range finding to multiple LED light source result, reduce the impact of measured deviation, reduce the error of position estimation.Present approach reduces the impact of single led range error on result, and adopt multiple LED as position reference, still can realize location when part LED is unavailable, improve the robustness of system.

Accompanying drawing explanation

Fig. 1 is the method flow diagram that the embodiment of the present invention is located based on many LED light sources.

Embodiment

Below in conjunction with drawings and Examples, the present invention is described in further detail.

Transmitting terminal of the present invention uses multiple LED as light source, when choosing N number of reference LED and finding range, supposes that receiving end is d to i-th estimated distance with reference to LED after revising _ci, and 1 < i < N, the coordinate of this LED is (x _i, y _i, z _i), then the estimation coordinate (x of receiving end _e, y _e, z _e) should meet:

${(x_e-x_i)}^2+{(y_e-y_i)}^2+{(z_e-z_i)}^2=d_{\mathrm{ci}}^2,(1<i<N)---\left(1\right)$

When i gets N number of value, can obtain N number of equation, the N number of equation of simultaneous can not solve the estimation coordinate (x of receiving end _e, y _e, z _e), but there is an optimum (x _e, y _e, z _e) make estimation coordinate all comparatively close to each distance with reference to LED, according to maximal possibility estimation, definition

$S={\mathrm{\&Sigma;}}_{i=1}^N{\mathrm{\&alpha;}}_i(\sqrt{{(x_e-x_i)}^2+{(y_e-y_i)}^2+{(z_e-z_i)}^2}-d_{\mathrm{ci}})---\left(2\right)$

Wherein α _ifor weight, meet and α _m/ α _n=d _n/ d _m(m ≠ n), 1<m<N, 1<n<N, namely from reference point i more close to, then α _ithere is larger weight.As estimation coordinate (x _e, y _e, z _e) value when making S minimum, think and now estimate coordinate (x _e, y _e, z _e) to all distances with reference to LED all relatively, be optimum solution.

Based on above principle, the method that the embodiment of the present invention is located based on many LED light sources, for making the effect of location optimum, multiple LED is cellular being arranged in a plane in field of illumination, as shown in Figure 1, specifically comprises the steps:

S1. receiving end receives the visible light signal sent from N number of LED simultaneously, wherein N > 3.Receiving end detects the transmission signal power of each LED, draws the estimated distance d of each LED to receiving end according to power-distance homologous thread _ei.Described power-distance homologous thread can obtain according to actual measurement or experience, and under the condition that LED emission angle and receiving end acceptance angle are all 0, the relation of power and distance meets logarithmic curve relation substantially.

S2. LED is had to the estimated distance d of emission angle and acceptance angle _eirevise, obtain corrected range d _ci.Corrected range d _cicomputing formula be: when multiple LED is honeycomb arrangement, L is LED minimum spacing, and h is the vertical range of receiving end to LED place plane, and n is correction factor.

Choose corrected range d _cithree nearest LED carry out triangle polyester fibre, the estimation coordinate (x of receiving end according to a preliminary estimate _e, y _e, z _e).Assuming that corrected range d _cithree nearest LED coordinate X=(x _i, y _i, z _i), (i=1,2,3), it is (x that receiving end records coordinate _e, y _e, z _e), then have:

${(x_e-x_1)}^2+{(y_e-y_1)}^2+{(z_e-z_1)}^2=d_{c1}^2$

${(x_e-x_2)}^2+{(y_e-y_2)}^2+{(z_e-z_2)}^2=d_{c2}^2$

${(x_e-x_3)}^2+{(y_e-y_3)}^2+{(z_e-z_3)}^2=d_{c3}^2$

Work as z ₁=z ₂=z ₃time, obtain AX=B, wherein:

$A=\left[\begin{array}{cc}{x}_2-x_1& y_2-y_1\\ x_3-x_1& y_3-y_1\end{array}\right],B=\left[\begin{array}{c}(d_{c1}^2-d_{c2}^2+x_2^2+y_2^2-x_1^2-y_1^2)/2\\ (d_{c1}^2-d_{c3}^2+x_3^2+y_3^2-x_1^2-y_1^2)/2\end{array}\right]$

Then $X=\left[\begin{array}{c}{x}_e\\ y_e\end{array}\right]={\left(A^{T}A\right)}^{-1}{A}^{T}B.$

S3. according to the corrected range d of each LED to receiving end _cicalculate weight α _i, wherein, d _ckrepresent d _c1~ d _cNin any one.

S4. estimation coordinate (x is chosen _e, y _e, z _e) near multiple coordinate points (x _j, y _k, z _e), neighbouring coordinate points meets: x _j=x _e+ j*step (-L≤j, k≤L), y _k=y _e+ k*step (-L≤j, k≤L), wherein L is positive integer, and step is the step-length of skew, by multiple coordinate points (x _j, y _k, z _e) bring formula (2) respectively into, calculate corresponding S value, choose the coordinate points (x that minimum S value is corresponding _j, y _k, z _e).

S5. judge coordinate points corresponding to minimum S value whether nearby coordinate points choose interval inside, that is, whether meet | x _j-x _e| <L*step, | y _j-y _e| <L*step, if not, enters S6; If so, S7 is entered.

S6., the coordinate points (x that minimum S value is corresponding is described _j, y _k, z _e) do not choosing interval inside, using coordinate points corresponding for this minimum S value as new estimation coordinate, jump to S4.

S7., the coordinate points (x that minimum S value is corresponding is described _j, y _k, z _e) choosing interval inside, this coordinate points (x _j, y _k, z _e) be optimum receiving end estimation coordinate.

The present invention is not limited to above-mentioned embodiment, and for those skilled in the art, under the premise without departing from the principles of the invention, can also make some improvements and modifications, these improvements and modifications are also considered as within protection scope of the present invention.The content be not described in detail in this instructions belongs to the known prior art of professional and technical personnel in the field.

Claims (6)

1., based on the method that many LED light sources are located, based on receiving end and multiple use LED as the transmitting terminal of light source, it is characterized in that, comprise step:

S1. receiving end receives from multiple visible light signal sent with reference to LED simultaneously; Receiving end detects the transmission signal power of each LED, draws the estimated distance of each LED to receiving end according to power-distance homologous thread;

S2. there is the estimated distance of emission angle and acceptance angle to revise to LED, obtain corrected range; Three LED choosing corrected range nearest carry out triangle polyester fibre, the estimation coordinate of receiving end according to a preliminary estimate;

S3. according to the corrected range calculating weight of each LED to receiving end;

S4. multiple coordinate points of estimation nearby coordinates are chosen, if estimation coordinate is (x _e, y _e, z _e), neighbouring coordinate points is (x _j, y _k, z _e), neighbouring coordinate points meets x _j=x _e+ j*step, y _k=y _e+ k*step (-L≤j, k≤L), wherein L is positive integer, and step is the step-length of skew, is brought into respectively by the coordinate of multiple described coordinate points

$S={\mathrm{\&Sigma;}}_{i=1}^N{\mathrm{\&alpha;}}_i(\sqrt{{(x_e-x_i)}^2+{(y_e-y_i)}^2+{(z_e-z_i)}^2}-d_{\mathrm{ci}}),$ Calculate corresponding S value, choose the coordinate points that minimum S value is corresponding, wherein N is the number with reference to LED, α _ifor weight, d _cibe the corrected range of i-th LED to receiving end;

S5. judge coordinate points corresponding to minimum S value whether nearby coordinate points choose interval inside, if not, enter S6; If so, S7 is entered;

S6. using coordinate corresponding for this minimum S value as new estimation coordinate, jump to S4;

S7. the coordinate that this minimum S value is corresponding is optimum receiving end estimation coordinate.

2. as claimed in claim 1 based on the method that many LED light sources are located, it is characterized in that: described transmitting terminal, multiple LED is cellular being arranged in same plane in field of illumination.

3. as claimed in claim 1 based on the method that many LED light sources are located, it is characterized in that: described power-distance homologous thread is obtained by actual measurement or experience.

4. as claimed in claim 1 based on the method that many LED light sources are located, it is characterized in that: in described S2, the computing formula of corrected range is wherein d _eifor the estimated distance in S1, d _cifor the corrected range of estimated distance, when multiple LED be honeycomb arrangement at same plane time, M is LED minimum spacing, and h is the vertical range of receiving end to LED place plane, and n is correction factor.

5. as claimed in claim 1 based on the method that many LED light sources are located, it is characterized in that: in described S2, assuming that three LED coordinate X=(x that corrected range is nearest _i, y _i, z _i), (i=1,2,3), the estimation coordinate of receiving end is (x _e, y _e, z _e), then have

$\begin{array}{c}{(x_e-x_1)}^2+{(y_e-y_1)}^1+{(z_e-z_1)}^2=d_{c1}^2\\ {(x_e-x_2)}^2+{(y_e-y_2)}^2+{(z_e-z_2)}^2=d_{c2}^2\\ {(x_e-x_3)}^2+{(y_e-y_3)}^2+{(z_e-z_3)}^2=d_{c3}^2\end{array}$

Work as z ₁=z ₂=z ₃time, obtain AX=B, wherein

$A=\left[\begin{array}{cc}{x}_2-x_1& y_2-y_1\\ x_3-x_1& y_3-y_1\end{array}\right],$ $B=\left[\begin{array}{c}(d_{c1}^2-d_{c2}^2+x_2^2+y_2^2-x_1^2-y_1^2)/2\\ (d_{c1}^2-d_{c3}^2+x_3^2+y_3^2-x_1^2-y_1^2)/2\end{array}\right]$

Then $X=\left[\begin{array}{c}{x}_e\\ y_e\end{array}\right]={\left(A^{T}A\right)}^{-1}{A}^{T}B.$

6. as claimed in claim 1 based on the method that many LED light sources are located, it is characterized in that: in described S3, pass through calculate weight α _i, wherein, meet d _cifor corrected range, d _ckrepresent d _c1~ d _cNin any one.