CN115902946A - Receiver positioning and rotation angle estimation system based on photodiode and LED - Google Patents

Abstract

The invention discloses a receiver positioning and rotation angle estimation system based on a photodiode and an LED, provides a novel optical positioning method and a rotation angle estimation method, and aims at the requirements of indoor positioning, robot navigation, game equipment and the like to obtain a high-precision two-dimensional positioning result. According to the method, incident light signals are collected through a PD array, and two-dimensional plane coordinates and a rotation angle of a receiver can be directly obtained through a simple expression through a proposed positioning algorithm and a rotation angle estimation algorithm. Compared with the existing three-dimensional indoor optical positioning method of arrival angle, arrival time, received signal strength and the like, the method has the advantages that: not relying on a synchronous or modem system; the operation complexity is low; only the PD array is required to receive the signal; the centimeter-level precision can be provided within a certain range; the rotation angle estimation can be directly obtained; does not rely on fixed optical power; the PD array can support high-speed visible light communications.

Description

Receiver positioning and rotation angle estimation system based on photodiode and LED

Technical Field

The invention belongs to the field of indoor optical positioning, and particularly relates to a receiver positioning and rotation angle estimation system based on a photodiode and an LED.

Background

The positioning technology is one of basic core technologies of Internet of things and artificial intelligence application. The visible light positioning system has the characteristics of low cost and high precision and has huge market potential. Currently, in the indoor positioning technology based on visible light, the visible light positioning algorithm based on Angle of Arrival (AOA) is considered as the most potential indoor positioning method with its low cost, high precision and low operation complexity. However, the existing visible light AOA positioning algorithm depends on a neural network or a numerical integration complex algorithm, and the realization cost is high; or rely on the lens, lead to the cost high, the power consumption is great, and do not support the visible light communication of the large bandwidth; or an electronic compass may be required to provide the rotation angle measurement. Therefore, the existing optical positioning AOA algorithm is difficult to be applied to low-cost mobile equipment, and the devices required for two-dimensional positioning are numerous and the algorithm is complex.

Disclosure of Invention

The invention aims to provide a receiver positioning and rotation angle estimation system based on photodiodes and LEDs, which designs two symmetrical LEDs by adopting a Photodiode (PD) array, has a simple positioning system algorithm independent of a neural network or numerical integration, reduces the hardware cost, supports high-speed visible light communication and provides rotation angle estimation, and solves the technical problems that a wireless optical positioning system has high hardware cost, high operation complexity and high equipment complexity, does not support wireless optical communication and needs an additional device to provide a rotation angle.

In order to solve the technical problems, the specific technical scheme of the invention is as follows:

a high-efficiency visible light positioning and rotation angle estimation system based on photodiodes and light emitting diodes comprises the following steps:

step 1, respectively measuring three-dimensional coordinates of two symmetrically distributed Light Emitting Diodes (LEDs) and recording the three-dimensional coordinates as coordinate vectors l ₁ And l ₂ ；

Step 2, combining 4 photodiodes PD with different orientations into an array as a receiver;

step 3, horizontally placing the receiver, pointing the central axis to a certain absolute direction, and using a vector u = [ u ] for the position of the receiver _x ,u _y ,u _z ] ^T Represents;

step 4, measuring the vertical distance between the LED and the receiver,

l _z，k -u _z ＝h _Lu (1)；

wherein the vertical distance is denoted h _Lu ，l _z，k Is the z coordinate of the kth light emitting diode LED;

step 5, defining the rotation angle beta of the receiver and the absolute direction, and rotating the matrix G from the world coordinate system to the relative coordinate system

Step 6, calculating and deriving to obtain the normalized incident light direction vector of the kth LED in a relative coordinate system

l _k Refers to the coordinate vector of the kth LED lamp;

step 7, substituting the formulas (1) and (2) into the formula (3)

Wherein r is _x，k For the x-direction component of the normalized incident light direction vector of the kth LED in the relative coordinate system, r _y，k Y-direction component of normalized incident light direction vector, r, of kth LED in relative coordinate system _z，k A z-direction component of a normalized incident light direction vector of the kth LED in a relative coordinate system; l _x，k Is the x coordinate of the kth LED; l _y，k Is the y coordinate of the kth LED;

step 8, obtaining a known parameter h through a formula (4) _Lu And a parameter r to be measured _z，k Associated with

Wherein equation (5.2) defines a circle centered at (l) _x，k ，l _y，k ) And a radius of

Step 9, setting l _x,1 ＝d,l _x,2 ＝-d,l _y,1 ＝l _y,2 Method for calculating user coordinates by combining equation (5) and equation (6) =0

Obtaining a set of two user coordinates which are mirror symmetric about the x-axis, wherein d is an assumed distance value;

according to vector cross product

Judging to obtain the position coordinates of the finally determined receiver;

step 10: obtaining a received light direction vector in a world coordinate system based on an estimated calculated receiver position

Is an estimated amount of the rotation angle beta>

Is an estimate of the position vector u, thus obtaining a relationship for the rotation angle beta

Wherein

Step 11: further from equation (10)

The receiver positioning and rotation angle estimation system based on the photodiode and the LED has the following advantages:

the invention adopts a cheap hardware platform to realize the two-dimensional optical positioning and rotation angle estimation functions, only comprises two symmetrical LEDs, a photodiode array and a low-speed signal processing unit, does not depend on complex algorithms such as a neural network or numerical integration, does not need an electronic compass, can obtain more accurate indoor two-dimensional positioning and can support high-speed visible light communication by applying the rotation angle estimation algorithm (formulas 9 and 10) through the characteristic of fixed vertical distance in two-dimensional coordinate estimation.

The optical positioning method and the rotation angle estimation method provided by the invention can obtain a high-precision two-dimensional positioning result aiming at the requirements of indoor positioning, robot navigation, game equipment and the like. According to the method, incident light signals are collected through a PD array, and two-dimensional plane coordinates and a rotation angle of a receiver can be directly obtained through a simple expression through a proposed positioning algorithm and a rotation angle estimation algorithm. Compared with the existing three-dimensional indoor optical positioning method such as Angle of Arrival (AOA), time of Arrival (TOA), received Signal Strength (RSS), etc., the present invention has the following advantages: not relying on a synchronous or modem system; the operation complexity is low; only the PD array is required to receive the signal; the centimeter-level precision can be provided within a certain range; the rotation angle estimation can be directly obtained; does not rely on fixed optical power; the PD array can support high-speed visible light communications.

Drawings

Fig. 1 shows an indoor positioning system based on two symmetrical LED and PD arrays.

FIG. 2 is a schematic diagram of mirror positioning and rotation angle estimation according to the present invention.

FIG. 3 is a block diagram of a two-dimensional optical positioning system of the present invention.

Detailed Description

For better understanding of the objects, structure and function of the present invention, a receiver positioning and rotation angle estimation system based on photodiode and LED will be described in detail with reference to the accompanying drawings.

The system frame is shown in fig. 3 and comprises two mirror-symmetrical LEDs, a photodiode array and a low-speed signal processing unit.

Firstly, three-dimensional coordinates of two symmetrically distributed LEDs are respectively measured and recorded as a coordinate vector l ₁ And l ₂ Such as (1 meter, 0 meter, 0.5 meter), (-1 meter, 0 meter, 0.5 meter);

then, 4 photodiodes with different orientations are combined into an array to be used as a receiver;

the receiver is horizontally placed, the central axis points to a certain absolute direction, and the position of the receiver is defined by a vector u = [ u ] _x ,u _y ,u _z ] ^T Represents;

assuming that the receiver only moves on the same plane, the distance (namely height) between the plane where the LED is located and the plane where the receiver is located is fixed, and the vertical distance between the LED lamp and the receiver at the moment is measured to obtain

l _z,k -u _z ＝h _Lu (1)；

Defining the rotation angle beta of the receiver and the absolute direction to obtain a rotation matrix G from the world coordinate system to the relative coordinate system

The normalized incident light direction vector of the kth LED in a relative coordinate system is obtained by calculation and derivation

Substituting equations (1) and (2) into equation (3) can obtain the incident light direction vector as

From equation (4), the known parameter h can be obtained _Lu And a parameter r to be measured _z,k Associated with

Wherein equation (5.2) defines a circle centered at (l) _x,k ,l _y,k ) And the radius is

By the formulas (5) and (6), the known parameter h can be set _Lu And a parameter r to be measured _z,k And linking to obtain the calculation of the user coordinates through further formula simplification and operation.

Let l _x,1 ＝d,l _x,2 ＝-d,l _y,1 ＝l _y,2 Method for calculating user coordinates by combining equation (5) and equation (6) =0

A set of two user coordinates which are mirror symmetric about the x-axis can be obtained according to the formula (7), and cross multiplication can be performed according to a vector

And judging to obtain the position coordinates of the finally determined receiver.

Based on the estimated and calculated receiver position, the received light direction vector in the world coordinate system can be obtained

Thus, the relation of the rotation angle beta can be obtained

Wherein

Respectively, an estimate of the angle of rotation beta and an estimate of the position vector u, so that a relation of the angle of rotation beta can be obtained

And is provided with

Further according to (10)

It is to be understood that the present invention has been described with reference to certain embodiments, and that various changes in the features and embodiments, or equivalent substitutions may be made therein by those skilled in the art without departing from the spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims (1)

1. An efficient visible light positioning and rotation angle estimation system based on photodiodes and light emitting diodes, comprising the steps of:

step 1, respectively measuring three-dimensional coordinates of two symmetrically distributed Light Emitting Diodes (LEDs) and recording the three-dimensional coordinates as coordinate vectors l ₁ And l ₂ ；

Step 2, combining 4 photodiodes PD with different directions into an array as a receiver;

step 3, horizontally placing the receiver, enabling the central axis to point to a certain absolute direction, and using the position of the receiver to point toAmount u = [ ] _x ,u _y ,u _z ] ^T Represents;

step 4, measuring the vertical distance between the LED and the receiver,

l _z,k -u _z ＝h _Lu (1)；

wherein the vertical distance is denoted h _Lu ,l _z,k Is the z coordinate of the kth light emitting diode LED;

step 5, defining the rotation angle beta of the receiver and the absolute direction, and rotating the matrix G from the world coordinate system to the relative coordinate system

Step 6, calculating and deriving to obtain the normalized incident light direction vector of the kth LED in a relative coordinate system

l _k Refers to the coordinate vector of the kth LED lamp;

step 7, substituting the formulas (1) and (2) into the formula (3)

Wherein r is _x,k For the x-direction component of the normalized incident light direction vector of the kth LED in the relative coordinate system, r _y,k Y-direction component of normalized incident light direction vector of kth LED in relative coordinate system, r _z,k A z-direction component of a normalized incident light direction vector of the kth LED in a relative coordinate system; l. the _x,k Is the x coordinate of the kth LED; l _y,k Is the y coordinate of the kth LED;

step 8, obtaining a known parameter h through a formula (4) _Lu And a parameter r to be measured _z,k Associated with

Wherein equation (5.2) defines a circle centered at (l) _x,k ,l _y,k ) And a radius of

Step 9, set l _x,1 ＝d,l _x,2 ＝-d,l _y,1 ＝l _y,2 User coordinate calculation method combining formula (5) and formula (6) =0

Obtaining a group of two user coordinates which are mirror-symmetrical about an x-axis, wherein d is an assumed distance value;

according to vector cross product

Judging to obtain the position coordinates of the finally determined receiver;

step 10: obtaining a received light direction vector in a world coordinate system based on an estimated calculated receiver position

Is an estimated amount of the rotation angle beta>

Is an estimate of the position vector u, thus obtaining a relationship for the rotation angle beta

Wherein

Step 11: further from equation (10)

/>

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