阅读说明：本技术 一种基于LED半功率角的投影DV-hop定位算法 (Projection DV-hop positioning algorithm based on LED half-power angle ) 是由 张月霞 陈爽 陈行 王晓健 于 2018-07-02 设计创作，主要内容包括：本发明提出一种基于LED半功率角的投影DV-hop定位算法。其中,所述算法为：基于非测距方式的DV-hop定位算法,待定位节点P随机位于布设有LED光源s<Sub>1</Sub>、s<Sub>2</Sub>、s<Sub>3</Sub>的可见光通信室内定位模型中,s<Sub>1</Sub>、s<Sub>2</Sub>、s<Sub>3</Sub>坐标已知,P点坐标未知,为(x,y,z)。首先,计算出P与s<Sub>1</Sub>、s<Sub>2</Sub>、s<Sub>3</Sub>的入射角值α<Sub>1p</Sub>、α<Sub>2p</Sub>、α<Sub>3p</Sub>,并根据s<Sub>1</Sub>、s<Sub>2</Sub>、s<Sub>3</Sub>已知位置计算出通信网络中的全网平均跳距AHS。然后,通过得到的α<Sub>1p</Sub>、α<Sub>2p</Sub>、α<Sub>3p</Sub>和AHS计算出s<Sub>1</Sub>、s<Sub>2</Sub>、s<Sub>3</Sub>与P点间距离的水平面映射值L<Sub>1p</Sub>、L<Sub>2p</Sub>、L<Sub>3p</Sub>。最后,利用S<Sub>1</Sub>、S<Sub>2</Sub>、S<Sub>3</Sub>投影到待定位节点P水平面上的三点(x<Sub>1</Sub>,y<Sub>1</Sub>,z)、(x<Sub>2</Sub>,y<Sub>2</Sub>,z)、(x<Sub>3</Sub>,y<Sub>3</Sub>,z)为圆心,L<Sub>1p</Sub>、L<Sub>2p</Sub>、L<Sub>3p</Sub>为半径作圆O<Sub>1</Sub>,O<Sub>2</Sub>,O<Sub>3</Sub>,再通过三边质心加权算法,求出圆O<Sub>1</Sub>,O<Sub>2</Sub>,O<Sub>3</Sub>重叠区域的质心,即得出待定位点P的坐标值(x,y,z)。(The invention provides a projection DV-hop positioning algorithm based on an LED half-power angle. Wherein the algorithm is as follows: DV-hop positioning algorithm based on non-ranging mode, wherein nodes P to be positioned are randomly distributed with LED light sources s 1 、s 2 、s 3 In the visible light communication indoor positioning model, s 1 、s 2 、s 3 The coordinates are known, and the coordinates of the point P are unknown as (x, y, z). First, P and s are calculated 1 、s 2 、s 3 Angle of incidence value alpha 1p 、α 2p 、α 3p And according to s 1 、s 2 、s 3 The known position calculates the average hop distance AHS of the whole network in the communication network. Then, by the obtained alpha 1p 、α 2p 、α 3p And AHS calculates s 1 、s 2 、s 3 Horizontal plane mapping value L of distance between P point and P point 1p 、L 2p 、L 3p . Finally, by S 1 、S 2 、S 3 Three points (x) projected onto the horizontal plane of the node P to be positioned 1 ，y 1 ，z)、(x 2 ，y 2 ，z)、(x 3 ，y 3 Z) is the center of a circle, L 1p 、L 2p 、L 3p Making a circle O for the radius 1 ，O 2 ，O 3 Then, the round O is calculated by the trilateral centroid weighting algorithm 1 ，O 2 ，O 3 And (4) obtaining the coordinate value (x, y, z) of the point P to be located by the centroid of the overlapped area.)

1. A projection DV-hop positioning algorithm based on LED half-power angles is characterized in that: DV-hop positioning algorithm based on non-ranging mode, and nodes P to be positioned are randomly arranged with LED light sources S₁、S₂、S₃In the visible light communication indoor positioning model, S₁、S₂、S₃The coordinates are known, and the coordinates of the point P are unknown as (x, y, z). First, P and S are calculated₁、S₂、S₃Angle of incidence value alpha_1p、α_2p、α_3pAnd according to S₁、S₂、S₃The known position calculates the average hop distance AHS of the whole network in the communication network. Then, by the obtained alpha_1p、α_2p、α_3pAnd AHS calculates S₁、S₂、S₃Horizontal plane mapping value L of distance between P point and P point_1p、L_2p、L_3p. Finally, by S₁、S₂、S₃Three points (x) projected onto the horizontal plane of the node P to be positioned₁，y₁，z)、(x₂，y₂，z)、(x₃，y₃Z) is the center of a circle, L_1p、L_2p、L_3pMaking a circle O for the radius₁，O₂，O₃Then, the round O is calculated by the trilateral centroid weighting algorithm₁，O₂，O₃And (4) obtaining the coordinate value (x, y, z) of the point P to be located by the centroid of the overlapped area.

2. The projection DV-hop localization algorithm based on LED half-power angle as claimed in claim 1, wherein the specific steps include:

1) establishing visible light communication indoor positioning model in room with positioning space of 5 mx 3m, LED light source S₁、S₂、S₃The coordinate is known and distributed on the roof, and P is a point to be positioned and the coordinate is unknown;

2) calculate P and S₁、S₂、S₃Angle of incidence value alpha_1p、α_2p、α_3pAnd according to S₁、S₂、S₃Calculating the average hop distance AHS of the whole network in the communication network according to the known position;

3) using alpha_1p、α_2p、α_3pAnd AHS calculates S₁、S₂、S₃Horizontal plane mapping value L of distance between P point and P point_1p、L_2p、L_3p；

4) By using S₁、S₂、S₃Three points (x) projected onto the horizontal plane of the node P to be positioned₁，y₁，z)、(x₂，y₂，z)、(x₃，y₃Z) is the center of a circle, L_1p、L_2p、L_3pMaking a circle O for the radius₁，O₂，O₃；

5) Solving the circle O by a trilateral centroid weighting algorithm₁，O₂，O₃The centroid of the overlapped area is the coordinate value (x, y, z) of the point P to be located;

6) and if the position of the point P to be positioned is changed, repeating the steps 2 to 6.

3. The projection DV-hop localization algorithm based on LED half-power angle as claimed in claim 2, wherein in step 1, the visible light communication indoor localization model is established in a room with a localization space of 5m x 3m, and the LED light source S is₁、S₂、S₃The coordinate is known and distributed on the roof, and P is a point to be positioned and the coordinate is unknown. Wherein S is₁、S₂、S₃The coordinates are known as (x)₁，y₁，z₁)、(x₂，y₂，z₂)、(x₃，y₃，z₃)，z₁＝z₂＝z₃3. The P coordinate is to be found and is set to (x, y, z).

4. The projection DV-hop localization algorithm based on LED half-power angle as claimed in claim 2, wherein in step 2, P and S are calculated₁、S₂、S₃Angle of incidence value alpha_1p、α_2p、α_3pAnd according to S₁、S₂、S₃The known position calculates the average hop distance AHS of the whole network in the communication network.

Wherein the value of the angle of incidence alpha is calculated_1p、α_2p、α_3pThe process is as follows: if the distance between the information source node and the node to be positioned is R, the expression is as follows:

information source node S_iAnd a node P to be positioned at an angle of incidence of a minimum of alpha_{ip min}And, and:

wherein d is the vertical distance from the node P to be positioned to the roof plane, and d is H-z.

Because of the fact that

the average hop distance AHS of the whole network in the communication network can be calculated by using the positions of known information source nodes to obtain:

5. the projection DV-hop localization algorithm based on LED half-power angle as claimed in claim 2, wherein in step 3, α is used_1p、α_2p、α_3pAnd AHS calculates S₁、S₂、S₃A horizontal plane mapping value L of the distance between the point and the point P_1p、L_2p、L_3p. Wherein, the horizontal plane mapping value calculation formula is as follows:

6. the projection DV-hop localization algorithm based on LED half-power angle as claimed in claim 2, wherein in step 4, S is used₁、S₂、S₃Three points (x) projected onto the horizontal plane of the node P to be positioned₁，y₁，z)、(x₂，y₂，z)、(x₃，y₃Z) is the center of a circle, L_1p、L_2p、L_3pMaking a circle O for the radius₁，O₂，O₃。

7. The projection DV-hop localization algorithm based on LED half-power angle as claimed in claim 2, wherein in step 5, the circle O is obtained through a trilateral centroid weighting algorithm₁，O₂，O₃And (4) obtaining the coordinate value (x, y, z) of the point P to be located by the centroid of the overlapped area. Wherein, the formula of the P coordinate (x, y, z) calculated by the trilateration method is as follows:

equation (6) in an ideal situation, three circles intersect at one point, but due to the influence of actual measurement errors, the three circles intersect two by two to form an overlapping region. Therefore, the centroid algorithm is used again, that is, the centroid of the overlapped area is found to replace the position of the point P to be located. So that the circle O₁、O₂Coordinates of intersection (x)_O12，y_O12，z_O12) The calculation formula is as follows:

calculate the intersection point (x) in the same way_O13，y_O13，z_O13)、(x_O23，y_O23，z_O23) And finally, obtaining the centroid of the overlapped area by using centroid weighting:

i.e. the coordinates (x, y, z) of the point P to be located are found.

8. The projection DV-hop localization algorithm based on LED half-power angle as claimed in claim 2, wherein in step 6, if the position of the point P to be located changes, steps 2 to 5 are repeated.

Technical Field

The invention relates to a visible light communication indoor positioning algorithm, in particular to a projection DV-hop positioning algorithm based on an LED half-power angle.

Background

Currently, the Global Positioning System (GPS) plays an important role in the field of positioning. However, GPS is not suitable for indoor positioning because it is difficult to receive GPS satellite signals in an indoor environment. The Visible Light Communication (VLC) technology is a novel green communication technology for realizing high-speed data transmission by utilizing high-frequency bright and dark flashing signals borne by a white light LED, and an indoor positioning system based on the VLC has less interference of multipath effect and higher positioning precision. In 2011, china promulgated out incandescent lamp roadmaps, and LEDs will become the next generation lighting technology, so that it is of great significance to study LED-based VLC indoor positioning technology.

At present, scholars at home and abroad research on VLC indoor positioning. Yoshino M et al, 2008, propose a method for implementing VLC indoor three-dimensional space positioning using an image sensor, with a positioning error smaller than 1.5M. In 2011, Kim H S et al propose a VLC positioning method based on carrier allocation, which reduces the positioning error to 6 cm. In 2015, Wu nan et al propose a method for realizing positioning by using a plurality of LED emitting ends, and the positioning error of the method can reach 3.5 cm. One-year-old, Asahando et al proposed a centroid-weighted improved TDOA location algorithm with an average location error of 3cm with a signal-to-noise ratio (SNR) of 2 dB.

The existing VLC indoor positioning method is improved to a certain extent in the aspect of reducing positioning errors, but the existing VLC indoor positioning method is based on a distance measurement mode, and the influence of positioning accuracy change caused by the characteristic of an LED half-power angle of a point to be positioned is not considered.

Disclosure of Invention

The invention aims to provide a projection DV-hop positioning algorithm based on an LED half-power angle. The algorithm utilizes a DV-hop positioning algorithm in a non-ranging mode, the distance between a node to be positioned and an information source node in a three-dimensional indoor space is projected and mapped into a two-dimensional plane for calculation, and the algorithm complexity is reduced. And the algorithm considers the influence of the positioning error caused by the LED half-power angle, and the accuracy is higher.

The invention provides a projection DV-hop positioning algorithm based on an LED half-power angle. Wherein the algorithm is as follows: DV-hop positioning algorithm based on non-ranging mode, and nodes P to be positioned are randomly distributed with LED light sources S₁、S₂、S₃In the visible light communication indoor positioning model, S₁、S₂、S₃The coordinates are known, and the coordinates of the point P are unknown as (x, y, z). First, P and S are calculated₁、S₂、S₃Angle of incidence value alpha_1p、α_2p、α_3pAnd according to S₁、S₂、S₃The known position calculates the average hop distance AHS of the whole network in the communication network. Then, by the obtained alpha_1p、α_2p、α_3pAnd AHS calculates s₁、s₂、s₃Horizontal plane mapping value L of distance from P point_1p、L_2p、L_3p. Finally, by S₁、S₂、S₃Three points (x) projected onto the horizontal plane of the node P to be positioned₁，y₁，z)、(x₂，y₂，z)、(x₃，y₃Z) is the center of a circle, L_1p、L_2p、L_3pMake a circle of radius o₁，o₂，o₃Then, the round o is calculated by the trilateral centroid weighting algorithm₁，o₂，o₃And (4) obtaining the coordinate value (x, y, z) of the point P to be located by the centroid of the overlapped area. The method comprises the following specific steps:

1) establishing visible light communication indoor positioning model in room with positioning space of 5 mx 3m, LED light source S₁、S₂、S₃The coordinate is known and distributed on the roof, and P is a point to be positioned and the coordinate is unknown;

2) calculate P and S₁、S₂、S₃Angle of incidence value alpha_1p、α_2p、α_3pAnd according to S₁、S₂、S₃Calculating the average hop distance AHS of the whole network in the communication network according to the known position;

3) using alpha_1p、α_2p、α_3pAnd AHS calculates S₁、S₂、S₃Horizontal plane mapping value L of distance between P point and P point_1p、L_2p、L_3p；

4) By using S₁、S₂、S₃Three points (x) projected onto the horizontal plane of the node P to be positioned₁，y₁，z)、(x₂，y₂，z)、(x₃，y₃Z) is the center of a circle, L_1p、L_2p、L_3pMake a circle of radius o₁，o₂，o₃；

5) The circle o is solved through a trilateral centroid weighting algorithm₁，o₂，o₃The centroid of the overlapped area is the coordinate value (x, y, z) of the point P to be located;

6) and if the position of the point P to be positioned is changed, repeating the steps 2 to 6.

In the step 1, a visible light communication indoor positioning model is established by using a room with a positioning space of 5m multiplied by 3m, and an LED light source s₁、s₂、s₃The coordinate is known and distributed on the roof, and P is a point to be positioned and the coordinate is unknown.

Wherein S is₁、S₂、S₃The coordinates are known as (x)₁，y₁，z₁)、(x₂，y₂，z₂)、(x₃，y₃，z₃)，z₁＝z₂＝z ₃3. The P coordinate is to be found and is set to (x, y, z).

In the above step 2, P and S are calculated₁、S₂、S₃Angle of incidence value alpha_1p、α_2p、α_3pAnd according to S₁、S₂、S₃The known position calculates the average hop distance AHS of the whole network in the communication network.

Wherein the value of the angle of incidence alpha is calculated_1p、α_2p、α_3pThe process is as follows: if the distance between the information source node and the node to be positioned is R, the expression is as follows:

information source node S_iAnd a node P to be positioned at an angle of incidence of a minimum of alpha_{ip min}And, and:

wherein d is the vertical distance from the node P to be positioned to the roof plane, and d is H-z.

Because of the fact that

So alpha_{ip min}Pi/6, so the angle of incidence α_ipHas a value range of [ pi/6, pi/2]. Due to uncertainty in the position of the node to be positioned, i.e. the actual angle of incidence α_ipIn that

Are distributed, for which purpose the mean values are taken

As the estimated angle of incidence. Then the estimated angle of incidence from equation (2) is:

the average hop distance AHS of the whole network in the communication network can be calculated by using the positions of known information source nodes to obtain:

in the above step 3, alpha is used_1p、α_2p、α_3pAnd AHS calculates S₁、S₂、S₃Horizontal plane mapping value L of distance between P point and P point_1p、L_2p、L_3p。

Wherein, the horizontal plane mapping value calculation formula is as follows:

in the above step 4, S is used₁、S₂、S₃Three points (x) projected onto the horizontal plane of the node P to be positioned₁，y₁，z)、(x₂，y₂，z)、(x₃，y₃Z) is the center of a circle, L_1p、L_2p、L_3pMake a circle of radius o₁，o₂，o₃。

In the step 5, the circle o is solved through the trilateral centroid weighting algorithm₁，o₂，o₃And (4) obtaining the coordinate value (x, y, z) of the point P to be positioned by the centroid of the overlapped area.

Wherein, the formula of the P coordinate (x, y, z) calculated by the trilateration method is as follows:

equation (6) in an ideal situation, three circles intersect at one point, but due to the influence of actual measurement errors, the three circles intersect two by two to form an overlapping region. Therefore, the centroid algorithm is used again, namely, the centroid of the overlapped area is solved to replace the position of the position point P to be determined. So that the circle O₁、O₂Coordinates of intersection (x)_O12，y_O12，z_O12) The calculation formula is as follows:

calculate the intersection point (x) in the same way_O13，y_O13，z_O13)、(x_O23，y_O23，z_O23) And finally, obtaining the centroid of the overlapping area by using centroid weighting:

i.e. the coordinates (x, y, z) of the point P to be located are found.

In the step 6, if the position of the point P to be located changes, the steps 2 to 5 are repeated.

The technical scheme of the invention has the advantages that: the method of the invention is different from a distance measurement mode algorithm used by a common positioning method, and utilizes a DV-hop algorithm in a non-distance measurement mode. The algorithm maps the distance between the node to be positioned and the information source node in the three-dimensional indoor space into a two-dimensional plane in a projection mode, and then the position coordinate of the node to be positioned is determined through the trilateral centroid weighting algorithm, so that the algorithm complexity is reduced. Moreover, the algorithm considers the positioning error influence caused by the half-power angle characteristic of the LED information source in the visible light communication, so that compared with the traditional visible light indoor positioning algorithm, the algorithm has the advantages of higher precision, stronger rationality and higher superiority.

While the invention will be described in connection with certain exemplary implementations and methods of use, it will be understood by those skilled in the art that it is not intended to limit the invention to these embodiments. On the contrary, the intent is to cover all alternatives, modifications and equivalents as included within the spirit and scope of the invention as defined by the appended claims.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

Drawings

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail with reference to the accompanying drawings, in which:

FIG. 1 shows a channel transmission model of a visible light communication system

FIG. 2 is a schematic diagram of a projection DV-hop VLC algorithm

FIG. 3 is a graph showing the relationship between the positioning error and the number of times of the algorithm

FIG. 4 is a graph comparing error between the improved algorithm and the conventional DV-hop algorithm

Detailed Description

The following describes in further detail embodiments of the present invention with reference to the accompanying drawings.

Fig. 1 is a channel transmission model of a visible light communication system. The signal source S sends out a modulated optical signal X (t), and the signal sink D uses a photodiode to receive a signal Y (t). Then:

Y(t)＝ηX(t)·h(t)+N(t) (9)

wherein eta is the photoelectric sensor conversion efficiency; n (t) is Gaussian white noise; h (t) is the channel impulse response, and the VLC system channel can be expressed as:

in the formula, R is the distance between the information source and the information sink; c is 3X 10⁸m/s is the speed of light; FOV represents the field angle of the source; a. the_rIs the receiving area of the photodetector;

and psi are the radiation angle and the reception angle, respectively; t is_s(ψ) is an optical filter gain of the signal sink; g (ψ) represents the gain of the optical concentrator. m represents a Lambertian emissivity coefficient having a value of

Wherein

Refers to SAHP of an LED light source.

The packaging of an LED affects its luminous intensity, generally considering the LED radiation pattern in a VLC system as obeying a lambertian distribution, and the luminous intensity and its luminous angle obey a cosine model:

P(φ)＝P₀cosφ (11)

in the formula, P₀The central luminous intensity of the LED. Therefore, when

Time, luminous intensityBecome half, i.e.

Fig. 2 is a schematic diagram of a projection DV-hop VLC algorithm. LED light source S₁、S₂、S₃Arranged on the roof and having known coordinates of (x)₁，y₁，z₁)、(x₂，y₂，z₂)、(x₃，y₃，z₃)，z₁＝z₂＝z ₃3. And P is a point to be positioned randomly in the room model, the coordinates are unknown, and (x, y, z) is set. In order to ensure the best communication effect, the node P to be positioned is assumed to be positioned at the information source node S₁、S₂、S₃Is within the SAHP coverage of (a).

FIG. 3 is a graph of the algorithm positioning error versus time. The graph shows the curve relation between the positioning error of the node to be positioned and the positioning times when the number of the information sources is 3. It can be seen that the positioning error shows a floating state with the simulation times, but the positioning error is basically less than 2.5cm, and the error is less than 0.5cm after many times. Therefore, the improved algorithm has high positioning precision.

Fig. 4 is a graph comparing the error of the improved algorithm and the conventional DV-hop algorithm. In the figure, a dotted line and a solid line represent a conventional DV-hop algorithm and a modified algorithm, respectively. It can be seen that the average positioning error of the improved algorithm is smaller than that of the conventional DV-hop algorithm, i.e. the positioning accuracy is improved compared with that of the conventional DV-hop algorithm. The solid line in the graph shows a descending trend, namely the average positioning error of the improved algorithm is reduced along with the increase of the number of the information source nodes, on one hand, the nodes to be positioned are positioned in more LED SAHP coverage ranges due to the increase of the information source nodes, so that the communication effect is better, and the measurement error is smaller; on the other hand, the number of the equations in the equation set is increased when the centroid is calculated by using the trilateral centroid weighting algorithm due to the increase of the number of the information sources, so that the calculation result is more accurate. The dotted lines in the graph show irregular states along with the increase of the source nodes because the number of hops between nodes in the traditional DV-hop algorithm has randomness, and the increase of the number of the source nodes can cause the number of hops in the network, the average hop distance and the positioning error to change.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and it is obvious that those skilled in the art can make various changes and modifications of the present invention without departing from the spirit and scope of the present invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include such modifications and variations.