CN110673093A - VLC (visible light communication) mixed indoor positioning method based on LED (light emitting diode) half-power angle - Google Patents

Abstract

The invention provides a VLC mixed indoor positioning method based on an LED half-power angle. Wherein, the method comprises the following steps: the node PN to be positioned is arranged with a plurality of LED light sources S₁、S₂…S_NAt any position in (not less than 3) VLC indoor positioning models, firstly, PN measures the arrival angle theta of signals from different LED light sources in the room model by using the antenna of the PN₁、θ₂…θ_N. Because the theoretical value of the LED half-power angle is

Therefore, when the PN is in the boundary range of the LED half-power angle, the arrival angle theta is pi/6. Then, from the angle of arrival θ₁、θ₂…θ_NTo select (pi/6, pi/2)]The maximum three values in the range are set as S for the corresponding LED light sources₁、S₂、S₃Then S can be used₁、S₂、S₃The known coordinates and the SAHP-RSS algorithm calculate the PN coordinate values (x, y, z). Secondly, e.g. asAngle of arrival of fruit theta₁、θ₂…θ_NIn (pi/6, pi/2)]If at least three values are not satisfied within the range, then from θ₁、θ₂…θ_NRandomly selecting two values theta₄、θ₅Let the LED light sources corresponding to the LED lamps be S₄、S₅According to theta₄、θ₅Value sum S₄、S₅Knowing the coordinates, the PN coordinate values (x, y, z) are calculated using the AOAD algorithm. And finally, if the PN position is changed, the steps are repeated to complete the positioning.

Description

VLC (visible light communication) mixed indoor positioning method based on LED (light emitting diode) half-power angle

Technical Field

The invention relates to a VLC indoor positioning algorithm, in particular to a VLC mixed indoor positioning method based on an LED half-power angle.

Background

With the rapid development of communication network technology, the demand of people for location services is gradually increasing. Statistically, people are moving in indoor environments such as homes, offices and the like for 80% of the time, and therefore the demand for indoor positioning is more and more urgent. 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 VLC has less interference of multipath effect and higher positioning precision. In 2011, the country publishes a street map of an eliminated incandescent lamp, and an LED becomes the next generation lighting technology, so that the research on the VLC indoor positioning technology based on the LED has important significance.

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. 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 characteristics of an LED are not fully utilized, and the existing algorithm is high in complexity and difficult to realize.

Disclosure of Invention

The invention aims to provide a VLC mixed indoor positioning method based on an LED half-power angle. Wherein, the method comprises the following steps: to be determinedThe bit node PN is arranged with a plurality of LED light sources S₁、S₂…S_NAt any position in (not less than 3) VLC indoor positioning models, firstly, PN measures the arrival angle theta of signals from different LED light sources in the room model by using the antenna of the PN₁、θ₂…θ_N. Then, from the angle of arrival θ₁、θ₂…θ_NTo select (pi/6, pi/2)]The maximum three values in the range are set as S for the corresponding LED light sources₁、S₂、S₃Then S can be used₁、S₂、S₃The known coordinates and the SAHP-RSS algorithm calculate the PN coordinate values (x, y, z). Second, if the angle of arrival θ₁、θ₂…θ_NIn (pi/6, pi/2)]If at least three values are not satisfied within the range, then from θ₁、θ₂…θ_NRandomly selecting two values theta₄、θ₅Let the LED light sources corresponding to the LED lamps be S₄、S₅According to theta₄、θ₅Value sum S₄、S₅Knowing the coordinates, the PN coordinate values (x, y, z) are calculated using the AOAD algorithm. And finally, if the PN position is changed, the steps are repeated to complete the positioning. The method comprises the following specific steps:

1) establishing a VLC indoor positioning model by using a room with a positioning space of 5m multiplied by 3 m;

2) PN utilizes self antenna to measure signal arrival angle theta from different LED light sources in room model₁、θ₂…θ_N；

3) From theta₁、θ₂…θ_NTo select (pi/6, pi/2)]The maximum three values in the range are set as S for the corresponding LED light sources₁、S₂、S₃；

4) By using S₁、S₂、S₃Calculating the coordinate value (x, y, z) of the PN by the known coordinate and SAHP-RSS algorithm, and jumping to the step 7;

5) if step 3 fails to be performed from theta₁、θ₂…θ_NIn (pi/6, pi/2)]Selecting three values in the range, and then randomly selecting two values theta₄、θ₅Let it respectivelyCorresponding LED light source is S₄、S₅；

6) According to theta₄、θ₅Value sum S₄、S₅Knowing the coordinates, calculating PN coordinate values (x, y, z) by using an AOAD algorithm;

7) if the PN position is changed, the above steps 2 to 6 are repeated.

In the step 1, a VLC indoor positioning model is established, and the positioning space is a room of 5m × 5m × 3 m. Several white light LED sources S₁、S₂…S_NArranged on the ceiling in a room, and the coordinates of the ceiling are known as (x)₁，y₁，z₁)、(x₂，y₂，z₂)…(x_N，y_N，z_N). And the PN is a node to be positioned, is positioned at any position in a room, has unknown coordinates and is set as (x, y, z).

In the step 2, the PN utilizes the antenna to measure the arrival angle theta of the signals from different LED light sources in the room model₁、θ₂…θ_N. Because the theoretical value of the LED half-power angle is

Therefore, when the PN is in the boundary range of the LED half-power angle, the arrival angle theta is pi/6. Namely theta epsilon (pi/6, pi/2) when PN is in the LED half-power angle coverage range]。

In the above step 3, from θ₁、θ₂…θ_NTo select (pi/6, pi/2)]The maximum three values in the range are set as S for the corresponding LED light sources₁、S₂、S₃. The larger the selected arrival angle value is, the closer the PN node is to the maximum light intensity of the center of the LED light source corresponding to the arrival angle value, the higher the light signal intensity is, the better the channel condition is, and the more suitable the SAHP-RSS algorithm is for positioning.

In the above step 4, S is used₁、S₂、S₃The known coordinates and the SAHP-RSS algorithm calculate the PN coordinate values (x, y, z).

The SAHP-RSS algorithm is based on the positioning principle of measuring the received signal strength P of PN_rIs of the formula(1) Calculating the distance d from the PN to the LED light source:

in the formula, R₀(phi) represents the LED emission angle gain; a. the_eff(Ψ) refers to the PN reception angle gain.

By using S₁、S₂、S₃And d found corresponding to the known coordinates₁、d₂、d₃PN coordinates (x, y, z) were calculated by trilateration:

and if the positioning is finished, jumping to the step 7 next.

In the above step 5, if the step 3 can not be performed from θ₁、θ₂…θ_NIn (pi/6, pi/2)]Selecting three values in the range, and then randomly selecting two values theta₄、θ₅Let the LED light sources corresponding to the LED lamps be S₄、S₅；

In the above step 6, according to θ₄、θ₅Value sum S₄、S₅Knowing the coordinates, the PN coordinate values (x, y, z) are calculated using the AOAD algorithm. The AOAD algorithm positioning principle is as follows:

let S₄、S₅Located on the roof and having coordinates known as (x)₄，y₄，z₄)、(x₅，y₅，z₅)，θ₄、θ₅Respectively receiving S for PN₄、S₅Angle of arrival of signal v₄、v₅Respectively, their corresponding azimuth angles. In order to simplify the algorithm model, the receiving angle of the antenna of the PN itself is not considered.

Using spherical coordinates, we get:

the radius r is eliminated, and the above equation becomes:

(y-y_i)＝tan(υ_i)(x-x_i)，i＝4，5 (4)

cos(υ_i)(z-z_i)＝tan(θ_i)(x-x_i)，i＝4，5 (5)

since the azimuth angle v is independent of the z-axis coordinate, the PN coordinate values x and y are calculated by equation (4), which includes:

converting it into a matrix form to obtain:

if and only if tan upsilon₅≠tanυ₄The formula (7) is established.

And then the PN coordinate value z is solved by the formula (5) by using the x and y values, the two arrival angle measurement values and the cosine theorem. Transforming equation (5) into:

therefore:

in the formula (9), Δ θ₅₄＝θ₅-θ₄Representing the difference in arrival angles, the equation may be solved to obtain the coordinate value z, i.e., to solve for the PN coordinate value (x, y, z).

In the step 7, if the PN position is changed, the steps 2 to 6 are repeated to recalculate the PN coordinate value.

The technical scheme of the invention has the advantages that: the method of the invention combines and considers the half-power angle characteristic of the LED light source in the VLC indoor positioning model, and accordingly provides a mixed VLC indoor positioning method which uses SAHP-RSS algorithm when the PN of the point to be positioned is in the LED light source half-power angle coverage range, and uses AOAD algorithm on the contrary. According to the positioning method, when the AOAD algorithm is utilized, indoor three-dimensional space positioning can be realized only by two LED light sources, and the algorithm complexity is reduced. Compared with the traditional VLC indoor positioning method, the method has the advantages of smaller positioning error and higher precision.

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 is a diagram of VLC system channel transmission model

FIG. 2 is a VLC model diagram for indoor positioning

FIG. 3 is a schematic diagram of AOAD algorithm positioning

FIG. 4 is a CRLB comparison graph of different algorithms RMSE

FIG. 5 is a Kalman filtering elimination algorithm error comparison diagram

Detailed Description

The specific idea of the algorithm is further described in detail below with reference to the accompanying drawings.

Fig. 1 is a diagram of a channel transmission model of a VLC 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)＝RX(t)·h(t)+N(t) (10)

wherein R 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, d 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

WhereinRefers 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 (12)

in the formula, P₀The central luminous intensity of the LED. Therefore, whenAt the same time, the luminous intensity becomes half, i.e.

Fig. 2 is a VLC indoor positioning model diagram. A room with a positioning space of 5m × 5m × 3m and a plurality of white light LED light sources S₁、S₂…S_NArranged on the ceiling in a room, and the coordinates of the ceiling are known as (x)₁，y₁，z₁)、(x₂，y₂，z₂)…(x_N，y_N，z_N). And the PN is a node to be positioned, is positioned at any position in a room, has unknown coordinates and is set as (x, y, z).

FIG. 3 is a schematic diagram of AOAD algorithm positioning. S₄、S₅Located on the roof and having coordinates known as (x)₄，y₄，z₄)、(x₅，y₅，z₅)，θ₄、θ₅Respectively receiving S for PN₄、S₅Angle of arrival of signal v₄、v₅Respectively, their corresponding azimuth angles.

Using spherical coordinates, we get:

the radius r is eliminated, and the above equation becomes:

(y-y_i)＝tan(υ_i)(x-x_i)，i＝4，5 (14)

cos(υ_i)(z-z_i)＝tan(θ_i)(x-x_i)，i＝4，5 (15)

since the azimuth angle ν is independent of the z-axis coordinate, the PN coordinate values x and y are calculated by equation (14) as follows:

converting it into a matrix form to obtain:

if and only if tan upsilon₅≠tanυ₄The expression (17) holds.

And then the PN coordinate value z is solved by the formula (15) by using the x and y values, the two arrival angle measurement values and the cosine theorem. Equation (15) is transformed into:

therefore:

in the formula (19), Δ θ₅₄＝θ₅-θ₄Representing the difference in arrival angles, the equation may be solved to obtain the coordinate value z, i.e., to solve for the PN coordinate value (x, y, z).

FIG. 4 is a CRLB comparison of different algorithms RMSE. In the figure, the curve RSS₁And RSS₂Respectively represents the CRLB and SNR relation curves of SAHP-RSS algorithm RMSE when PN is outside and inside LEDSAHP coverage range. Curve AOAD represents the CRLB to SNR relationship for AOAD algorithm RMSE. As can be seen, the RSS curves are obtained at the same SNR₂Lower than curve RSS₁And AOAD, which shows that the SAHP-RSS algorithm has higher positioning precision when the SAHP-RSS algorithm is within the LED SAHP coverage range. Furthermore, the curve AOAD is lower than the RSS₁When the LED SAHP coverage is out, the positioning accuracy of the AOAD algorithm is higher than that of the SAHP-RSS algorithm, and meanwhile, the rationality of the VLC hybrid positioning method based on the LED half-power angle is verified.

FIG. 5 is a Kalman filter elimination algorithm error comparison graph. In the figure, a broken line and a solid line respectively represent the relation curves of the system RMSE and the PN random positioning times before and after Kalman filtering. As can be seen from the figure, the solid line is obviously lower than the dotted line, namely the Kalman filtering effectively eliminates the positioning algorithm error, and after the filtering processing, the system RMSE can reach below 2cm, thereby meeting the requirement of indoor high-precision positioning.

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 to 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 also intended to include such modifications and variations.

Claims (9)

1. A VLC mixed indoor positioning method based on LED half-power angles is characterized in that:

the node PN to be positioned is arranged with a plurality of LED light sources S₁、S₂…S_NAt any position in (not less than 3) VLC indoor positioning models, firstly, PN measures the arrival angle theta of signals from different LED light sources in the room model by using the antenna of the PN₁、θ₂…θ_N. Then, from the angle of arrival θ₁、θ₂…θ_NTo select (pi/6, pi/2)]The maximum three values in the range are set as S for the corresponding LED light sources₁、S₂、S₃Then S can be used₁、S₂、S₃The known coordinates and the SAHP-RSS algorithm calculate the PN coordinate values (x, y, z). Second, if the angle of arrival θ₁、θ₂…θ_NIn (pi/6, pi/2)]If at least three values are not satisfied within the range, then from θ₁、θ₂…θ_NRandomly selecting two values theta₄、θ₅Let the LED light sources corresponding to the LED lamps be S₄、S₅According to theta₄、θ₅Value sum S₄、S₅Knowing the coordinates, the PN coordinate values (x, y, z) are calculated using the AOAD algorithm. And finally, if the PN position is changed, repeating the steps.

2. The VLC hybrid indoor positioning method as claimed in claim 1, wherein said specific steps are:

1) establishing a VLC indoor positioning model by using a room with a positioning space of 5m multiplied by 3 m;

2) PN utilizes self antenna to measure signal arrival angle theta from different LED light sources in room model₁、θ₂…θ_N；

3) From theta₁、θ₂…θ_NTo select (pi/6, pi/2)]The maximum three values in the range are set as S for the corresponding LED light sources₁、S₂、S₃；

4) By using S₁、S₂、S₃Calculating the coordinate value (x, y, z) of the PN by the known coordinate and SAHP-RSS algorithm, and jumping to the step 7;

5) if step 3 fails to be performed from theta₁、θ₂…θ_NIn (pi/6, pi/2)]Selecting three values in the range, and then randomly selecting two values theta₄、θ₅Let the LED light sources corresponding to the LED lamps be S₄、S₅；

6) According to theta₄、θ₅Value sum S₄、S₅Knowing the coordinates, calculating PN coordinate values (x, y, z) by using an AOAD algorithm;

7) if the PN position is changed, the above steps 2 to 6 are repeated.

3. The VLC hybrid indoor positioning method according to claim 2, wherein in step 1, a VLC indoor positioning model is established, and a positioning space is a 5m × 5m × 3m room. Several white light LED sources S₁、S₂…S_NArranged on the ceiling in a room, and the coordinates of the ceiling are known as (x)₁，y₁，z₁)、(x₂，y₂，z₂)…(x_N，y_N，z_N). And the PN is a node to be positioned, is positioned at any position in a room, has unknown coordinates and is set as (x, y, z).

4. The VLC mixing indoor positioning method as claimed in claim 2, wherein in said step 2, PN measures arrival angle θ of signals from different LED light sources in the room model by using its own antenna₁、θ₂…θ_N. Because the theoretical value of the LED half-power angle is

Therefore, when the PN is in the boundary range of the LED half-power angle, the arrival angle theta is pi/6. Namely theta epsilon (pi/6, pi/2) when PN is in the LED half-power angle coverage range]。

5. The VLC mixing indoor positioning method as claimed in claim 2, wherein in said step 3, from θ₁、θ₂…θ_NTo select (pi/6, pi/2)]The maximum three values in the range are setThe LED light sources corresponding to the LED light sources are S₁、S₂、S₃. The larger the selected arrival angle value is, the closer the PN node is to the maximum light intensity of the center of the LED light source corresponding to the arrival angle value, the higher the light signal intensity is, the better the channel condition is, and the more suitable the SAHP-RSS algorithm is for positioning.

6. The VLC mixing indoor positioning method as claimed in claim 2, wherein in said step 4, S is utilized₁、S₂、S₃The known coordinates and the SAHP-RSS algorithm calculate the PN coordinate values (x, y, z).

The SAHP-RSS algorithm is based on the positioning principle of measuring the received signal strength P of PN_rCalculating the distance d from the PN to the LED light source by the formula (1):

in the formula, R₀(phi) represents the LED emission angle gain; a. the_eff(Ψ) refers to the PN reception angle gain.

By using S₁、S₂、S₃And d found corresponding to the known coordinates₁、d₂、d₃PN coordinates (x, y, z) were calculated by trilateration:

and if the positioning is finished, jumping to the step 7 next.

7. The VLC hybrid indoor positioning method as claimed in claim 2, wherein in said step 5, if step 3 fails to follow θ₁、θ₂…θ_NIn (pi/6, pi/2)]Selecting three values in the range, and then randomly selecting two values theta₄、θ₅Let the LED light sources corresponding to the LED lamps be S₄、S₅。

8. According toThe VLC mixing indoor positioning method as claimed in claim 2, wherein in said step 6, according to θ₄、θ₅Value sum S₄、S₅Knowing the coordinates, the PN coordinate values (x, y, z) are calculated using the AOAD algorithm. The AOAD algorithm positioning principle is as follows:

let S₄、S₅Located on the roof and having coordinates known as (x)₄，y₄，z₄)、(x₅，y₅，z₅)，θ₄、θ₅Respectively receiving S for PN₄、S₅Angle of arrival of signal v₄、v₅Respectively, their corresponding azimuth angles. In order to simplify the algorithm model, the receiving angle of the antenna of the PN itself is not considered.

Using spherical coordinates, we get:

the radius r is eliminated, and the above equation becomes:

(y-y_i)＝tan(υ_i)(x-x_i)，i＝4，5 (4)

cos(υ_i)(z-z_i)＝tan(θ_i)(x-x_i)，i＝4，5 (5)

since the azimuth angle v is independent of the z-axis coordinate, the PN coordinate values x and y are calculated by equation (4), which includes:

converting it into a matrix form to obtain:

if and only if tan upsilon₅≠tanυ₄The formula (7) is established.

And then the PN coordinate value z is solved by the formula (5) by using the x and y values, the two arrival angle measurement values and the cosine theorem. Transforming equation (5) into:

therefore:

in the formula (9), Δ θ₅₄θ₅-θ₄Representing the difference in arrival angles, the equation may be solved to obtain the coordinate value z, i.e., to solve for the PN coordinate value (x, y, z).

9. The VLC hybrid indoor positioning method as claimed in claim 2, wherein in said step 7, if the PN position is changed, said steps 2 to 6 are repeated to recalculate the PN coordinate value.

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