TW201604570A - A visible light positioning method and a system thereof - Google Patents

Abstract

A visible light positioning method comprising the following steps: (1) A light power transform step and an electric power transform step calculates an angle/gain relation from the Lambertian model of light signal, (2) An actual position coordinate is calculated by a coordinate calculating step and the electric power transform step, (3) A function modeling method calculates a prediction position coordinate according to a function fitting, (4) An error modifying method aimed to modify an error between the actual position coordinate and the prediction position coordinate, then, the error modifying method calculates the prediction position which had been modified already. This invention uses the light signal to complete a coordinate positioning, the coordinate calculating step and the electric power transform step lets this invention calculates the actual position coordinate without figuring out an angle of the light signal.

Description

Method and system for positioning visible light

Positioning method, especially a positioning method using visible light

The purpose of the positioning system is to provide accurate geographical information of people, vehicles, ships, and aircraft, and is widely used in navigation, emergency rescue, transportation planning and other applications. Outdoor positioning systems using RF signals are quite common, such as the Global Positioning System (GPS). However, in an indoor environment, the satellite positioning signal of the outside is unstable due to the shielding of the building, and because the relative distance of the indoor space is short, it is not easy to achieve accurate positioning. At present, there are many kinds of indoor positioning technologies, and theories are different, but they are not too complicated or have poor performance.

A method for positioning a visible light, comprising the following steps: Step 1: A plurality of light receiving devices receive a plurality of optical signals outputting an output signal; Step 2, an optical power conversion step and an electrical power conversion step to Lambert The model calculates an angle/gain relationship; step 3, a standard calculation step and the electric power conversion step calculate an actual position coordinate according to the electric power and a system parameter; Step 4: A function simulation method performs a function fitting according to the angle/gain relationship, the function fitting calculates a fitting function and calculates a predicted position coordinate by the fitting function; step 5: an error correction method is The error between the actual position coordinate and the predicted position coordinate, the predicted position coordinate is compensated and corrected, and the corrected predicted position coordinate is calculated.

Wherein, the function fitting method is to fit the function to the angle/gain relationship by an exponential function model.

Wherein, the error correction method is an error compensation algorithm, and the error compensation algorithm is as follows: In the error compensation algorithm: d _{ei is} the new shortest straight line distance calculated by the error correction method; The shortest linear distance between the ith set of the light output device and the light receiving device calculated according to the actual situation; and The compensation function corresponding to the i-th group of the i-th set of the light output device, wherein versus The coordinates of the actual location.

The error positive method multiplies the compensation function by the shortest actual distance to complete the correction of the predicted position coordinate, and the compensation function is as follows: Wherein: the highest order of a compensation function for Q and R; Q r, respectively, and that the order of the predicted position coordinates; p _{qr, i} is the i-th group of the light output apparatus q 10 corresponding to the order r a compensation parameter; and u(n) is a continuous unit step function.

The electric power conversion steps are as follows: Where: P _{e is} the electrical power; C _e is the conversion constant of the optical power converted to electrical power; L _r (α) is the radiation angle gain of the light output device; L _i (β) is the incident angle gain of the light receiving device ; α is the radiation angle at which the light output device outputs the optical signal; and β is the incident angle at which the light receiving device receives the optical signal.

The system parameter is a shortest linear distance, wherein: the shortest linear distance is affected by the spatial size of a positioning space.

Further, the coordinate calculation step is a three-side positioning step using the Bisch's theorem. The actual coordinate position is a coordinate of the light receiving device in the positioning space; the predicted coordinate position is a coordinate of the light receiving device in the positioning space. The light output device is an LED light source; the light receiving device is a light detector.

It can be seen from the above that the present invention has the following advantages:

1. The present invention uses visible light as a signal for an indoor positioning system and an error correction method to improve indoor positioning accuracy.

2. By receiving the optical signal to complete the coordinate positioning, it is not necessary to establish the positioning information in advance.

The coordinate calculation step and the electric power conversion method make the invention not need to perform the optical signal angle judgment, and only need to calculate the electric power ( P _e ) received by the light receiving device and calculate the shortest linear distance by using the known system parameters ( d _e ), and then calculate the actual position coordinates.

10‧‧‧Light output device

20‧‧‧Light receiving device

30‧‧‧Location space

( P _e )‧‧‧electric power

( x _d , y _d , z _d ) ‧‧‧Light receiving device coordinates

( x _ti , y _ti , z _ti ) ‧‧‧Light output device coordinates

( d _ei )‧‧‧ Estimated shortest straight line distance

( d _i )‧‧‧The shortest straight line distance

( L _r (α) )‧‧‧radiation angle gain

( L _i (β) ) ‧‧‧inclination angle gain

( L _t (θ) ) ‧ ‧ total angle gain

( α )‧‧‧A radiation angle

( β )‧‧‧ an incident angle

( θ )‧‧‧Common angle

( α _1/2 )‧‧‧radiation half power angle

( β _1/2 )‧‧‧incident half power angle

( m _r )‧‧‧radiation valves

( m _i )‧‧‧number of incident valves

( m _t )‧‧‧ total cosine order

1 is a side view of a positioning space according to a preferred embodiment of the present invention;

2 is a schematic diagram of a relationship curve according to a preferred embodiment of the present invention

3 is a schematic diagram of a relationship curve according to a preferred embodiment of the present invention

4 is a schematic diagram of a relationship curve according to a preferred embodiment of the present invention

Figure 5 is a graph showing the relationship between an ideal Lambertian model and an actual exponential function in accordance with a preferred embodiment of the present invention.

6 is a graph showing the relationship between an ideal Lambertian model and an actual exponential function in accordance with a preferred embodiment of the present invention;

7 is a diagram of an ideal actual/predicted position coordinate map drawn by a Lambertian model in accordance with a preferred embodiment of the present invention;

Please refer to FIG. 1 and FIG. 2 , which are preferred embodiments of a visible light positioning method according to the present invention. The visible light positioning method uses a plurality of light output devices 10 to output one optical signal and a plurality of light receiving devices that receive the optical signal. 20: Positioning a plurality of actual position coordinates in a positioning space 30, wherein the actual position coordinates are positions of the light receiving device 20 in the positioning space 30, and each of the optical signals has a different optical frequency, and the light receiving Device 20 can identify different frequencies for each of the optical signals. Wherein, the radiation angle (α) of the optical signal when the optical signal is output by the light output device 10 and the light signal received by the light receiving device 20 are calculated according to a Lambertian model and an exponential function. An angle/gain relationship between an incident angle (β) of a signal and a radiation angle gain ( L _r (α) ) and an incident angle gain ( L _i (β) ), the angle/gain relationship can be a comparison table In the embodiment of the present invention, the angle/gain relationship is a relationship curve, as shown in FIGS. 2, 3, and 4. The invention utilizes the angle/gain relationship to perform a function fitting, and the function fitting calculates a fitting function according to the angle/gain relationship by a mathematical method, and the function value of the fitting function coincides or approximates the angle/gain relationship. By substituting the various simulation parameters in the fitting function, a predicted position coordinate representing the position of the light receiving device 20 can be calculated, and further, error correction and compensation are performed on the predicted position coordinate, so that the predicted position coordinate conforms to the actual Position coordinates.

In the embodiment of the present invention, the light output device 10 is an LED light source, and the light receiving device can be a photo detector (PD) or a mobile communication device, such as a mobile phone. The optical output device 10 transmits the optical signal. The optical receiving device 20 is coupled to a processing unit. After the optical signal is received by the optical receiving device 20, the optical receiving device 20 converts the optical signal into an electrical power ( P _e ). The light receiving device 20 outputs the optical power of the optical signal and the intensity of the electrical power ( P _e ) to the processing unit by an electrical signal, and the processing unit calculates the optical receiving device 20 by determining the electrical signal. The actual position coordinates in the space 30 are located. The processing unit may be a microprocessor, a controller (MCU), or a device having an arithmetic function, which is not limited herein.

The visible light positioning method may include a positioning calculation method, a function fitting method, and an error correction method, wherein the positioning calculation method calculates the actual position coordinate according to the intensity of the optical signal and the intensity of the electrical power ( P _e ), wherein the The positioning calculation method includes a standard calculation step, an optical power conversion step, and an electric power conversion step. The function fitting method calculates the fitting function according to the angle/gain relationship.

The error correction method calculates the predicted position coordinate, because of an external factor, such as: installation angle, ambient light interference, causing a prediction error between the predicted position coordinate and the actual position coordinate, the error correction method is performed The prediction error is corrected such that the predicted position coordinates conform to the actual position coordinates.

In the embodiment of the present invention, the coordinate calculation step is a three-side positioning step using the Bis's theorem, and the calculation of the Bis's theorem is performed by using the light output device 10 and the position coordinates of the light receiving device 20 in the positioning space 30, respectively. In the embodiment of the present invention, the three-dimensional coordinate system of the positioning space 30 is defined by three axes of xyz , and the calculation formula of the Bisch's theorem is as shown in Equation 1:

Wherein x _d , y _d , z _d represent a light receiving device coordinate ( x _d , y _d , z _d ) of the light receiving device 20 in the three-dimensional coordinate system of the positioning space 30; x _ti , y _ti , z _ti Representing a light output device coordinate ( x _ti , y _ti , z _ti ) in the three-dimensional coordinate system of the light output device 10 in the positioning space 30, in the embodiment of the present invention, the light installed in the positioning space 30 The output devices 30 are three groups, which are respectively a first light output device, a second light output device, and a third light output device, so i=1~3; d _{i is between} the light output device 10 and the light receiving device 20 One of the shortest linear distances ( d _i ), in the embodiment of the present invention, the light output device 30 installed in the positioning space 30 is three groups, so i=1~3.

Further, in the embodiment of the present invention, the light output device 10 and the light receiving device 20 are respectively mounted on the top surface and the bottom surface of the positioning space 30, such as the ceiling and the floor of the indoor space, wherein the positioning space is preset in the embodiment of the present invention. The top surface and the bottom surface of the 30 are parallel to each other. As shown in Equation 2, the z-axis coordinates of the light output device 10 in the positioning space 30 are all the same value.

The coordinate calculation step can perform the light receiving device coordinates ( x _d , y _d , z _d ) of the formula 1 and the light output device coordinates ( x _ti , y _ti , z _ti ) under the condition of the above formula 2 After a linear transformation, the shortest straight line distance ( d _i ) is obtained by a matrix operation, as shown in Equation 3. To calculate the X matrix in Equation 3, the processing unit 40 performs an inverse matrix operation on Equation 3 to obtain Equation 4, which is known from Equation 4.

2AX=D (3)

The matrix A is a mounting matrix. In the embodiment of the present invention, the mounting matrix is based on the first light output device, and the second light output device and the third light output device are used as horizontal coordinate systems. The amount of change in distance from the vertical distance. As shown in Equation 5:

The matrix X is a coordinate vector of the light receiving device of the light receiving device in the plane coordinate system, as shown in Equation 6:

The matrix D is the shortest straight line distance vector, as shown in Equation 7:

In the embodiment of the present invention, the positioning calculation method calculates the actual position coordinate according to the intensity of the optical signal and the intensity of the electric power ( P _e ), wherein the angle is set according to the light output device 10 and the light receiving device 20 And the distance between the optical signal received by the optical receiving device 20 and the generated electrical power ( P _e ). In the optical power conversion step, the optical receiving device 20 receives the optical signal and generates the optical signal. A relationship between a photocurrent ( i _e ) and the electric power ( P _e ) is as shown in Equation 8; and the electric power ( P _e ) and an output optical power ( P _t ) of the light output device 10 and the light receiving device 20 The relationship of one of the received optical powers ( P _r ) is as shown in Equation 9.

Wherein d represents the distance between the light output device 10 and the mounting position of the light receiving device 20; R(α) is the radiation intensity gain of the light output device 10, as shown in Equation 10, A(β) is the light The effective receiving area gain of the receiving device 20 is as shown in Equation 11, where α is a radiation angle ( α ) of the optical output device 10 outputting the optical signal and β is an incident angle of the optical receiving device 20 receiving the optical signal ( β ), as shown in Figure 1.

A(β)=A cos β O(β)C(β) (11)

The codes in the formulas 10 and 11 are: m is the number of radiation valves, as shown in Formula 12.

A is the surface area of the light receiving device 20, O(β) is the optical filter gain, and C(β) is the condensing mirror gain.

This electric power conversion step is as shown in Equation 14.

The function and code in the formula 14 are: C _e is a conversion constant for converting optical power into electric power; L _r (α) is a radiation angle gain ( L _r (α) ) of the light output device, as shown in Equation 15, For example, please refer to FIG. 2 , which is an ideal relationship diagram of the radiation angle gain ( L _r (α) ) and the radiation half power angle ( α _1/2 ) drawn by the Lambertian model;

L _i (β) is the incident angle gain ( L _i (β) ) of the light receiving device, as in Equation 16, wherein, referring to FIG. 3, the incident angle gain ( L ) plotted by the Lambertian model An ideal relationship diagram of _i (β) ) and the incident half power angle ( β _1/2 );

( d ) represents the shortest distance ( d ) of one of the mounting positions of the light output device 10 and the light receiving device 20.

Wherein the codes in the formulas 15 and 16 are: m _r is the number of radiation valves ( m _r ), which varies as the radiation half power angle ( α _1/2 ) of the light output device is as shown in Equation 17.

m _i is the number of incident valves ( m _i ), which varies with the incident half power angle ( β _1/2 ) of the light receiving device, as shown in Equation 18.

In the embodiment of the present invention, the light output device 10 and the light receiving device 20 are respectively mounted on the top surface and the bottom surface of the positioning space 30, such as the ceiling and the floor of the indoor space, wherein the positioning space 30 is preset in the embodiment of the present invention. The top surface and the bottom surface are parallel to each other. As shown in Equation 2, the z-axis coordinates of the light output device 10 in the positioning space 30 are all the same value. The radiation angle ( α ) and the incident angle ( β ) in Equations 17 and 18 are equal to each other because the top surface and the bottom surface of the positioning space 30 are parallel to each other. Further, the radiation angle gain ( L _r (α) ) and the incident angle gain ( L _i (β) ) of Equations 15 and 16 can be expressed by an angle total gain ( L _t (θ) ), as shown in Equation 20:

Wherein the code in Equation 20 is: m _t is the total cosine order ( m _t ).

θ is a common angle ( θ ), and the common angle in the embodiment of the present invention

( θ ) = the radiation angle ( α ) and the incident angle ( β ).

Please refer to FIG. 4 , which is the total gain L _t (θ ) drawn by the Lambertian model corresponding to the radiation half power angle ( α _1/2 ) of 50 degrees and the incident half power angle ( β _{1 ). /2} ) is the ideal relationship graph at 22 degrees. Further, the electric power ( P _e ) can be rewritten by the total angle gain L _t (θ) , as shown in Equation 21:

Please refer to FIG. 5 and FIG. 6 , which are respectively drawn by a Lambertian model and an exponential function, and the content is the radiation angle gain ( L _t (α) ) and the radiation half power angle ( α _1/2 ). The relationship graph is shown in Fig. 6. The graph is plotted by the Lambertian model and the exponential function, and the content is the relationship between the incident angle gain ( L _i (β) ) and the incident half power angle ( β _1/2 ). .

In the embodiment of the present invention, the function fitting method calculates the fitting function by fitting the angle/gain relationship by an exponential function model, and calculates the predicted position coordinate by using the fitting function, and the fitting function is as shown in Equations 26 and 27 Shown as follows:

The fitting parameters in the fitting functions of the formulas 26 and 27 are as shown in Table 1:

Please refer to FIG. 7 , which is an ideal actual/predicted position coordinate mapping diagram of the actual position coordinate and the predicted position coordinate in a Lambertian model according to an embodiment of the present invention, wherein the predicted position coordinate is ideally used. The actual position coordinate should be matched, but the prediction error occurs due to the influence of the external factor on the predicted position coordinate and the actual position coordinate.

The error correction method in the embodiment of the present invention is an error compensation algorithm, and the error correction method compensates and corrects the error between the actual position coordinate and the predicted position coordinate, so that the corrected predicted position coordinate is more consistent with the actual The position coordinate, the calculation formula of the error correction method is as shown in Equation 28:

The code and function in the formula 28 are: d _{ei is} the new shortest straight line distance calculated by the error correction method; The shortest linear distance between the ith group of the light output device 10 and the light receiving device 20 calculated according to actual conditions; a compensation function corresponding to the i-th group of the i-th set of the light output device 10, wherein the code is , The coordinates of the actual location.

The compensation function in Equation 28 is as shown in Equation 29:

The code and function in Equation 29 are: (1) Q and R are the highest order of the compensation function, and in the embodiment of the present invention, Q = R = N ( N is a positive integer); (2) q and r is the order of the coordinates of the predicted position; (3) p _{qr, i} is a compensation parameter of the qth and rth orders corresponding to the i-th group of transmitters; (4) u ( n ) is a continuous unit step The function, as shown in Equation 30:

Further, in the error correction method according to the embodiment of the present invention, error compensation of different orders is performed, and error compensation of different orders produces different results for the error correction method, and higher-order error compensation makes the predicted position coordinate The smaller the error between the coordinates of the actual position and the lower table, the results of the first step of error compensation (Q=1, R=1), the compensation parameters are shown in Table 3:

The following table shows the results of error compensation second order (Q=2, R=2). The compensation parameters are shown in Table 4:

The visible light positioning method of the present invention comprises the following steps: Step 1: The light receiving device 20 receives the optical signal output by the light output device 10, and the optical signal is converted into the electrical power ( P _e ) by the light receiving device 20; The optical power conversion step and the electric power conversion step calculate the angle/gain relationship by a Lambertian model; the third step, the coordinate calculation step, and the electric power conversion step are performed according to the optical receiver 20 receiving the optical signal conversion The electrical power ( P _e ) intensity and the reference to the system parameter, the actual position coordinate is calculated; step four, the function simulation method performs the function fitting according to the angle/gain relationship, and the function fits the fitting function and calculates Calculating the predicted position coordinate by using the fitting function; Step 5: The error correction method compensates and corrects the predicted position coordinate by the error compensation algorithm for the error between the actual position coordinate and the predicted position coordinate.

It can be seen from the above that the present invention has the following advantages:

1. The present invention uses visible light as a signal for an indoor positioning system and an error correction method to improve indoor positioning accuracy.

2. By receiving the optical signal to complete the coordinate positioning, it is not necessary to establish the positioning information in advance.

The coordinate calculation step and the electric power conversion step enable the present invention to perform angle judgment of the optical signal, and only need to calculate the electric power ( P _e ) received by the optical receiving device and calculate the shortest linear distance by using known system parameters ( d _e ), and then calculate the actual position coordinates.

10‧‧‧Light output device

20‧‧‧Light receiving device

30‧‧‧Location space

Claims (10)

A method for positioning a visible light, comprising: a plurality of light receiving devices receiving an optical signal outputted by a plurality of light output devices; an optical power conversion step and an electrical power conversion step calculating an angle/gain relationship using a Lambertian model; A standard calculation step and the electric power conversion step calculate an actual position coordinate according to the electric power and a system parameter; a function simulation method performs a function fitting according to the angle/gain relationship, and the function fitting calculates a fitting function and The fitting function calculates a predicted position coordinate; an error correction method compensates and corrects the predicted position coordinate for the error between the actual position coordinate and the predicted position coordinate, and calculates the corrected predicted position coordinate. For example, in the method of applying visible light according to item 1 of the patent scope, the function fitting method is to fit the function to the angle/gain relationship by an exponential function model. For example, in the method of applying visible light according to the first or second aspect of the patent, the error correction method is an error compensation algorithm, and the error compensation algorithm is as follows: In the error compensation algorithm: d _{ei is} the new shortest straight line distance calculated by the error correction method; The shortest linear distance between the ith set of the light output device and the light receiving device calculated according to the actual situation; and The compensation function corresponding to the i-th group of the i-th set of the light output device, wherein versus The coordinates of the actual location. For example, in the third aspect of the patent scope, a method for applying visible light is applied. The error positive method multiplies the compensation function by the shortest actual distance to complete the correction of the predicted position coordinate. The compensation function is as follows: Where: Q and R are the highest order of the compensation function; q and r are the orders of the predicted position coordinates; p _{qr, i} is the qth and rth order corresponding to the i-th group of the light output device A compensation parameter; and u ( n ) is a continuous unit step function. As for the method of applying visible light according to item 4 of the patent scope, the electric power conversion steps are as follows: Where: P _{e is} the electrical power; C _e is the conversion constant of the optical power converted to electrical power; L _r (α) is the radiation angle gain of the light output device; L _i (β) is the incident angle gain of the light receiving device ; α is the radiation angle at which the light output device outputs the optical signal; and β is the incident angle at which the light receiving device receives the optical signal. The method for positioning visible light according to item 5 of the patent scope, the system parameter is a receiving device height. For example, in the method of applying visible light according to item 6 of the patent scope, the coordinate calculation step is a three-side positioning step using the Pearson's theorem. For example, in the method of applying visible light according to Item 7, the actual coordinate position is a coordinate of the light receiving device in the positioning space; the predicted coordinate position is a coordinate of the light receiving device in the positioning space. For example, in the method of positioning visible light according to Item 8 of the patent, the light output device is an LED light source; the light receiving device is a light detector. A positioning system for applying visible light, comprising: a light output device, a light receiving device and a processing unit, the light output device and the light receiving device, wherein: the light output device can output an optical signal; the light receiving device can Receiving the optical signal, converting the optical signal into electrical power, and converting the intensity of the electrical power into an electrical signal output; and the processing unit is coupled to the optical receiving device, and the processing unit receives the electrical signal of the electrical power intensity, Calculating an actual position coordinate and a predicted position coordinate of the light receiving device in a positioning space according to the electrical signal, and compensating and correcting the error between the actual position coordinate and the predicted position coordinate.