A visible light positioning method, device and system based on dual-frequency orthogonal beacon

Abstract

The present invention provides a visible light positioning method, device and system based on dual-frequency orthogonal beacons, the method comprising: receiving dual-frequency orthogonal beacons emitted by LED light sources, and calculating the differential phase of each dual-frequency orthogonal beacon currently received; calculating the time difference of the dual-frequency orthogonal beacons according to the differential phase of the dual-frequency orthogonal beacons; and calculating the position coordinates of the positioning terminal in the positioning area according to the time difference of each dual-frequency orthogonal beacon and the coordinate information of each LED light source. The present invention transmits dual-frequency orthogonal beacons to the positioning terminal, and the positioning terminal measures the phase information of the dual-frequency orthogonal beacons emitted by each LED light source, thereby obtaining the differential phase and propagation time difference formed in the propagation process of the dual-frequency orthogonal beacons emitted by each LED light source, and then combines the geometric positioning method to realize indoor visible light positioning, without measuring the propagation time of the signal, greatly improving the indoor visible light positioning accuracy, and meeting the use requirements of indoor high-precision positioning.

Description

Technical Field

[0001] The present invention relates to the field of indoor positioning technology, and in particular to a visible light positioning method, device and system based on dual-frequency orthogonal beacons. Background Art

[0002] With the rapid development of smart phones and mobile Internet, people's demand for positioning and navigation services is increasing. Most of people's lives are spent indoors, and a large number of positioning needs of users, corporate production machines, IoT devices, etc. also occur indoors; however, because indoor scenes are blocked by buildings, the global navigation satellite positioning system (GNSS) signal decays rapidly or even disappears completely, which cannot meet the navigation and positioning needs in indoor scenes.

[0003] Currently, LED-based visible light positioning is a very hot industry development and research topic. In the indoor positioning system based on visible light, the positioning system is divided into positioning terminals and network equipment (including LED light sources). The network equipment of the positioning system emits visible light signals that meet specific rules, called positioning beacons. The positioning algorithm of the positioning terminal mainly achieves indoor positioning by measuring the propagation time of the positioning beacons emitted by each LED of the network equipment.

[0004] However, the traditional visible light positioning method needs to measure the propagation time of the signal, which requires the positioning end to be completely synchronized with the LED end. Therefore, the positioning accuracy is not high. The positioning accuracy in a small scene range is about 0.1m, which is difficult to meet the requirements of indoor high-precision positioning. Summary of the invention

[0005] Based on this, the purpose of the present invention is to provide a visible light positioning method, device and system based on dual-frequency orthogonal beacons to solve the technical problem of insufficient positioning accuracy in existing visible light positioning methods.

[0006] A visible light positioning method based on a dual-frequency orthogonal beacon according to an embodiment of the present invention is applied to a positioning terminal and used to locate the position of the positioning terminal in a positioning area preset indoors, wherein a plurality of LED light sources are arranged indoors, and the LED light sources can periodically transmit a dual-frequency orthogonal beacon to the positioning area in a pulse form, wherein the dual-frequency orthogonal beacon includes two orthogonal positioning signals of different frequencies, and the method includes:

[0007] Receive the dual-frequency orthogonal beacon emitted by the LED light source, and calculate the differential phase of each dual-frequency orthogonal beacon currently received, where the differential phase of the dual-frequency orthogonal beacon is the phase difference between the two positioning signals of the dual-frequency orthogonal beacon;

[0008] Calculating the time difference of the dual-frequency orthogonal beacon according to the differential phase of the dual-frequency orthogonal beacon, where the time difference of the dual-frequency orthogonal beacon is the reception time difference of two positioning signals of the dual-frequency orthogonal beacon;

[0009] The position coordinates of the positioning terminal in the positioning area are calculated according to the time difference of each of the dual-frequency orthogonal beacons and the coordinate information of each of the LED light sources.

[0010] In addition, the visible light positioning method based on dual-frequency orthogonal beacons according to the above embodiment of the present invention may also have the following additional technical features:

[0011] Further, the step of calculating the differential phase of each dual-frequency orthogonal beacon currently received includes:

[0012] Performing a fast Fourier transform on the currently received dual-frequency orthogonal beacon to obtain a frequency spectrum of the dual-frequency orthogonal beacon;

[0013] Converting the frequency spectrum of the dual-frequency orthogonal beacon into a phase-frequency diagram, and obtaining the phase values ​​of the two positioning signals of the dual-frequency orthogonal beacon at corresponding frequencies from the phase-frequency diagram of the dual-frequency orthogonal beacon;

[0014] The differential phase of the dual-frequency orthogonal beacon is calculated according to the phase values ​​of the two positioning signals of the dual-frequency orthogonal beacon at corresponding frequencies.

[0015] Furthermore, the differential phase of the dual-frequency orthogonal beacon satisfies the following conditional formula:

[0016]

[0017] in, is the differential phase of the dual-frequency orthogonal beacon currently received from the i-th LED light source, and They are respectively the phase values ​​of the two positioning signals of the dual-frequency orthogonal beacon emitted by the i-th LED light source currently received at the corresponding frequencies.

[0018] Furthermore, the time difference of the dual-frequency orthogonal beacon satisfies the following conditional formula:

[0019]

[0020] Among them, Δt i f1 is the time difference of the dual-frequency orthogonal beacon currently received from the i-th LED light source, i and f2 i They are respectively the corresponding frequencies of the two positioning signals of the dual-frequency orthogonal beacon emitted by the i-th LED light source currently received.

[0021] Furthermore, the step of calculating the position coordinates of the positioning terminal in the positioning area according to the time difference of each of the dual-frequency orthogonal beacons and the coordinate information of each of the LED light sources includes:

[0022] Constructing a nonlinear least squares equation group according to the time difference of each of the dual-frequency orthogonal beacons and the coordinate information of each of the LED light sources;

[0023] The nonlinear least squares equations are solved by using a convex optimization algorithm to obtain the position coordinates of the positioning terminal in the positioning area.

[0024] Furthermore, the step of using a convex optimization algorithm to solve the nonlinear least squares equations to obtain the position coordinates of the positioning terminal in the positioning area includes:

[0025] Performing a linear transformation on the nonlinear least squares equation system to obtain a linear least squares equation system, and converting the linear least squares equation system into a matrix form to obtain a least squares equation system in matrix form;

[0026] Based on the preset solution constraints, a convex optimization algorithm is used to solve the least squares equations in the matrix form to obtain the position coordinates of the positioning terminal in the positioning area;

[0027] The constraint conditions to be solved include the coordinates of each vertex in the positioning area.

[0028] Furthermore, the nonlinear least squares equation system L is expressed as:

[0029]

[0030] In the formula, r i is the distance from the ith LED light source to the positioning terminal, r i＝ Δt i *c, Δt i is the time difference of the dual-frequency orthogonal beacon emitted by the i-th LED light source currently received, c is the speed of light, Tx i , Ty i , Tz i represents the coordinates of the i-th LED light source, Rx, Ry, and Rz represent the position coordinates of the positioning terminal to be solved in the positioning area;

[0031] Among them, the linear least squares equation system L' is expressed as:

[0032]

[0033] Among them, the least squares equation system L" in matrix form is expressed as:

[0034]

[0035] Among them, B=AX.

[0036] A visible light positioning device based on a dual-frequency orthogonal beacon according to an embodiment of the present invention is applied to a positioning terminal and used to locate the position of the positioning terminal in a positioning area preset indoors, wherein a plurality of LED light sources are arranged indoors, and the LED light sources can periodically transmit a dual-frequency orthogonal beacon to the positioning area in a pulse form, wherein the dual-frequency orthogonal beacon includes two orthogonal positioning signals of different frequencies, and the device includes:

[0037] A signal receiving module, used to receive the dual-frequency orthogonal beacon emitted by the LED light source, and calculate the differential phase of each dual-frequency orthogonal beacon currently received, where the differential phase of the dual-frequency orthogonal beacon is the phase difference between the two positioning signals of the dual-frequency orthogonal beacon;

[0038] A time difference calculation module, used to calculate the time difference of the dual-frequency orthogonal beacon according to the differential phase of the dual-frequency orthogonal beacon, where the time difference of the dual-frequency orthogonal beacon is the reception time difference of two positioning signals of the dual-frequency orthogonal beacon;

[0039] The positioning module is used to calculate the position coordinates of the positioning terminal in the positioning area according to the time difference of each of the dual-frequency orthogonal beacons and the coordinate information of each of the LED light sources.

[0040] The present invention also proposes a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the visible light positioning method based on dual-frequency orthogonal beacons is implemented.

[0041] The present invention also proposes a visible light positioning system based on a dual-frequency orthogonal beacon, and the visible light positioning system based on a dual-frequency orthogonal beacon comprises:

[0042] A positioning network device is arranged indoors, the positioning network device comprises a plurality of LED light sources, the LED light sources can periodically transmit a dual-frequency orthogonal beacon to a preset positioning area indoors in a pulse form, the dual-frequency orthogonal beacon comprises two positioning signals of different frequencies and orthogonal to each other;

[0043] A positioning terminal is arranged indoors, and the positioning terminal includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the visible light positioning method based on the dual-frequency orthogonal beacon as described above is implemented to locate the position of the positioning terminal in the positioning area based on the dual-frequency orthogonal beacon emitted by the LED light source.

[0044] Compared with the existing technology: by transmitting dual-frequency orthogonal beacons to the positioning terminal, the positioning terminal measures the phase information of the dual-frequency orthogonal beacons emitted by each LED light source, thereby obtaining the differential phase and propagation time difference formed in the propagation process of the dual-frequency orthogonal beacons emitted by each LED light source, and then combining the geometric positioning method to realize indoor visible light positioning, there is no need to measure the propagation time of the signal, which greatly improves the indoor visible light positioning accuracy and meets the use requirements of indoor high-precision positioning. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 A schematic diagram of the structure of a visible light positioning system based on dual-frequency orthogonal beacons provided in an embodiment of the present invention;

[0046] Figure 2 is a flow chart of a visible light positioning method based on dual-frequency orthogonal beacons in the first embodiment of the present invention;

[0047] Figure 3 is a flow chart of a visible light positioning method based on dual-frequency orthogonal beacons in the second embodiment of the present invention;

[0048] Figure 4 Schematic diagram of the structure of a visible light positioning device based on dual-frequency orthogonal beacons in the third embodiment of the present invention.

[0049] The following specific implementations will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0050] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0051] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0053] Currently available positioning technologies include base station positioning, global navigation satellite positioning system (GNSS), WiFi positioning, Bluetooth positioning, visible light positioning, etc.

[0054] Base station positioning: Base station positioning is generally used for mobile phone users. Mobile phone base station positioning service is also called mobile location service (LBS, Location Based Service). It obtains the location information of mobile terminal users through the network of telecommunications mobile operators (such as GSM network). Since the signal is easily interfered when the base station is positioned, the inaccuracy of its positioning is inherently determined, with an accuracy of about 150 meters, which is basically impossible to drive and navigate. The positioning condition is that it must be in a location with base station signal, the mobile phone is in the SIM card registration state (it is not possible to turn on WiFi in flight mode and remove the SIM card), and it must receive signals from 3 base stations, regardless of whether it is indoors or not. However, the positioning speed is super fast, and it can be positioned once there is a signal. At present, its main use is to quickly and roughly understand your location without GPS and WiFi. Moreover, the current base station positioning technology has a positioning accuracy of more than meters and consumes a lot of power. Positioning based on LPWAN (Low-Power Wide-Area Network, low-power wide area network) base stations, such as LoRa, NB-IOT, etc., although the power consumption is low, the positioning accuracy is also relatively low, generally around 100 meters. Base station-based positioning is currently generally used outdoors, but if it is used indoors, it will require the deployment of many base stations, which is very costly.

[0055] GNSS positioning: GNSS positioning is mainly used outdoors, with a civilian accuracy of about a few meters. The accuracy is not high, the power consumption is too large, and the signal is easily blocked. The positioning system cannot be used indoors or in relatively closed spaces.

[0056] WiFi positioning: WiFi positioning technology is mainly used for indoor positioning. It refers to the wireless local area network (WLAN) composed of wireless access points, such as wireless routers, which can achieve positioning, tracking, monitoring and other tasks in complex environments. It is based on and premised on the location information of network nodes (wireless access points), and uses a combination of empirical testing and signal propagation models to locate the connected mobile devices. The highest accuracy is about 1 meter to 20 meters. However, it is easily affected by the surrounding environment, resulting in low accuracy. Moreover, its coverage radius is only about 90 meters, and its energy consumption is relatively large.

[0057] Bluetooth positioning: Bluetooth positioning is based on the RSSI (Received Signal Strength Indication) positioning principle. Depending on the positioning end, Bluetooth positioning methods are divided into network-side positioning and terminal-side positioning. However, it is necessary to record the signal strength of a large number of determined location points before positioning, and then determine the location of the mobile device by comparing the signal strength of the Bluetooth signal received by the mobile device with the established fingerprint library. The fingerprint library of signal strength requires a large number of people to collect in the early stage, and the scene is difficult to fix, and the positioning accuracy is between 1 meter and 20 meters. Although the energy consumption is small, the accuracy is not high, the stability is poor, and the maintenance cost required is high.

[0058] At present, light emitting diodes (LEDs) have absolutely dominated indoor lighting systems since the mid-1990s due to their extremely high luminous efficiency. In addition, LEDs have advantages such as ultra-high bandwidth, environmental protection, and ultra-wideband, which make them have advantages in indoor positioning, such as ultra-high bandwidth, environmental protection, and strong electromagnetic interference resistance. At the same time, considering that the positioning accuracy of the above-mentioned global navigation satellite positioning system (GNSS), WiFi positioning, and Bluetooth positioning in indoor scenes is seriously insufficient, visible light can become an important supplement for indoor positioning, thus giving birth to the LED-based visible light positioning system.

[0059] Currently, LED-based visible light positioning is a very hot industry development and research topic. In the indoor positioning system based on visible light, the positioning system is divided into positioning terminal and network equipment. The network equipment contains multiple LED light sources. The network equipment of the positioning system emits visible light signals that meet specific rules, which are called positioning beacons. The positioning algorithm of the positioning terminal mainly achieves indoor positioning by measuring the propagation time of the positioning beacons emitted by each LED of the network equipment.

[0060] However, the traditional visible light positioning method needs to measure the propagation time of the signal, which requires the positioning end to be completely synchronized with the LED end, so the positioning accuracy is not high. The positioning accuracy in a small scene range is about 0.1m, which is difficult to meet the requirements of indoor high-precision positioning. In order to solve the problem of insufficient accuracy of the existing visible light positioning method, the embodiment of the present invention proposes a visible light positioning method based on a dual-frequency orthogonal beacon, so as to achieve indoor positioning by measuring the differential information of the dual-frequency orthogonal beacon, thereby eliminating the need to measure the propagation time of the signal, thereby improving the positioning accuracy. The specific scheme and principle are discussed through the following embodiments.

[0061] The following embodiments can be applied to Figure 1 In the visible light positioning system based on dual-frequency orthogonal beacons shown, Figure 1The figure shows a visible light positioning system based on dual-frequency orthogonal beacons provided in one embodiment of the present invention, wherein the visible light positioning system includes a positioning network device and a positioning terminal, wherein:

[0062] The positioning network device and the positioning terminal are both arranged indoors. The positioning terminal is in a preset positioning area indoors. The visible light positioning system is mainly used to locate the position of the positioning terminal in the positioning area. The positioning network device includes a plurality of LED light sources arranged in a dispersed manner. The plurality of LED light sources are not coplanar. The LED light sources can periodically transmit a pre-modulated beacon signal to the positioning area in a pulse form. The beacon signal in the embodiment of the present invention is specifically a dual-frequency orthogonal beacon. The positioning terminal receives the dual-frequency orthogonal beacons emitted by each LED light source, and locates its own position according to the received dual-frequency orthogonal beacon.

[0063] Specifically, the positioning area can be any legal area indoors, such as a living room, hall, bedroom, conference room, office, etc. LED light sources can be arranged on the ceiling of the positioning area, and the LED light sources can provide both indoor lighting and visible light positioning. The positioning terminal can be, but is not limited to, a robot (such as a sweeping robot), a mobile phone, a logistics vehicle, etc., which can move in the positioning area. For example, a sweeping robot can clean in the positioning area. During the cleaning process, the position of the sweeping robot is located by the visible light positioning system.

[0064] In addition, in the embodiment of the present invention, the positioning network device also includes a plurality of dimmers, and each LED light source is connected to a dimmer. By controlling the parameters of the dimmer, the LED light source can emit the required dual-frequency orthogonal beacon.

[0065] It should be pointed out that Figure 1 The structure shown does not constitute a limitation on the visible light positioning system based on dual-frequency orthogonal beacons. In other embodiments, the visible light positioning system based on dual-frequency orthogonal beacons may include fewer or more components than shown in the figure, or combine certain components, or arrange the components differently.

[0066] Embodiment 1

[0067] See also Figure 2 , shown is a visible light positioning method based on dual-frequency orthogonal beacons in the first embodiment of the present invention, which is applied to a positioning terminal and is used to locate the position of the positioning terminal in a preset positioning area indoors. A plurality of LED light sources are arranged indoors, and the LED light sources can periodically transmit dual-frequency orthogonal beacons to the positioning area in a pulse form. The dual-frequency orthogonal beacons include two orthogonal positioning signals with different frequencies. The method specifically includes steps S01-S03.

[0068] Step S01, receiving the dual-frequency orthogonal beacon emitted by the LED light source, and calculating the differential phase of each dual-frequency orthogonal beacon currently received, wherein the differential phase of the dual-frequency orthogonal beacon is the phase difference between two positioning signals of the dual-frequency orthogonal beacon.

[0069] Specifically, after the LED light source is turned on and / or when a positioning request is received, the LED light source will periodically radiate a dual-frequency orthogonal beacon to the positioning area in a pulsed form, where the dual-frequency orthogonal beacon emitted by the i-th LED light source can be expressed as x i0 = Beacon 1 + Beacon 2, where Beacon 1 and Beacon 2 are two positioning signals, and the frequency of Beacon 1 is f1 i , the frequency of beacon 2 is frequency f2 i , beacon 1 and beacon 2 are orthogonal to form a dual-frequency orthogonal beacon. In addition, the positioning terminal in the positioning area will receive each dual-frequency orthogonal beacon sent by each LED light source. Assuming there are n LED light sources, i = 1, 2, 3...n.

[0070] At the same time, after receiving each dual-frequency orthogonal beacon, the positioning terminal can convert the received dual-frequency orthogonal beacon into a corresponding phase-frequency diagram, and then obtain the corresponding frequency (i.e., f1) of the phase-frequency diagram. i and f2 i ) find the respective phase values ​​of beacon 1 and beacon 2 of the dual-frequency orthogonal beacon, and then determine the differential phase of the dual-frequency orthogonal beacon based on the phase difference between beacon 1 and beacon 2.

[0071] Step S02: Calculate the time difference of the dual-frequency orthogonal beacon according to the differential phase of the dual-frequency orthogonal beacon, where the time difference of the dual-frequency orthogonal beacon is the reception time difference of two positioning signals of the dual-frequency orthogonal beacon.

[0072] Among them, the time difference of the dual-frequency orthogonal beacon satisfies the following conditional formula:

[0073]

[0074] Among them, Δt i f1 is the time difference of the dual-frequency orthogonal beacon currently received from the i-th LED light source, i and f2 i are the corresponding frequencies of the two positioning signals of the dual-frequency orthogonal beacon emitted by the i-th LED light source currently received, is the differential phase of the dual-frequency orthogonal beacon currently received from the i-th LED light source, where satisfy:

[0075]

[0076] in, and They are respectively the phase values ​​of the two positioning signals of the dual-frequency orthogonal beacon emitted by the i-th LED light source currently received at the corresponding frequencies.

[0077] Step S03: Calculate the position coordinates of the positioning terminal in the positioning area according to the time difference of each of the dual-frequency orthogonal beacons and the coordinate information of each of the LED light sources.

[0078] In summary, the visible light positioning method based on dual-frequency orthogonal beacons in the above embodiments of the present invention transmits dual-frequency orthogonal beacons to the positioning terminal, and the positioning terminal measures the phase information of the dual-frequency orthogonal beacons emitted by each LED light source, thereby obtaining the differential phase and propagation time difference of the dual-frequency orthogonal beacons emitted by each LED light source during the propagation process, and then combines the geometric positioning method to realize indoor visible light positioning. There is no need to measure the propagation time of the signal, and the positioning accuracy of 1.5 cm can be achieved, which is very close to the theoretical limit and meets the use requirements of indoor high-precision positioning.

[0079] Embodiment 2

[0080] See also Figure 3 , shown is a visible light positioning method based on dual-frequency orthogonal beacons in the second embodiment of the present invention, which is applied to a positioning terminal and is used to locate the position of the positioning terminal in a preset positioning area indoors. A plurality of LED light sources are arranged indoors, and the LED light sources can periodically transmit dual-frequency orthogonal beacons to the positioning area in a pulse form. The dual-frequency orthogonal beacons include two orthogonal positioning signals with different frequencies. The method specifically includes steps S11 to S18.

[0081] Step S11, receiving a dual-frequency orthogonal beacon emitted by the LED light source.

[0082] In the specific application scenario of the first embodiment, a total of 16 LED light sources are arranged indoors. First, it is necessary to assign reasonable installation coordinates (Tx i , Ty i , Tz i ), i = 1, 2, 3 ... 16, and these 16 LED light sources are divided and numbered along the X-axis, Y-axis, and Z-axis directions. Note that the m LED lights cannot be coplanar during installation. m can be 16, even if all LED light sources are not coplanar, so that better positioning accuracy can be achieved. For example but not limitation, the installation coordinates of the 16 LED light sources can be as follows:

[0083] (Tx1, Ty1, Tz1) = (0.5, 0.5, -1) (Tx9, Ty9, Tz9) = (6.5, 0.5, 1)

[0084] (Tx2, Ty2, Tz2) = (0.5, 3.5, 0) (Tx 10 , Ty 10 , Tz 10 ) = (6.5, 3.5, -1)

[0085] (Tx3, Ty3, Tz3) = (0.5, 6.5, 1) (Tx 11 , Ty 11 , Tz 11 ) = (6.5, 6.5, 0)

[0086] (Tx4, ​​Ty4, Tz4) = (0.5, 9.5, -1) (Tx 12 , Ty 12 , Tz 12 ) = (6.5, 9.5, 1)

[0087] (Tx5, Ty5, Tz5) = (3.5, 0.5, 0) (Tx 13 , Ty 13 , Tz 13 ) = (9.5, 0.5, -1)

[0088] (Tx6, Ty6, Tz6) = (3.5, 3.5, 1) (Tx 14 , Ty 14 , Tz 14 ) = (9.5, 3.5, 0)

[0089] (Tx7, Ty7, Tz7) = (3.5, 6.5,-1) (Tx 15 , Ty 15 , Tz 15 ) = (9.5, 6.5, 1)

[0090] (Tx8, Ty8, Tz8) = (3.5, 9.5, 0) (Tx 16 , Ty 16 , Tz 16 ) = (9.5, 9.5, -1)

[0091] Then, each LED light source needs to be given the same output power P and dual-frequency signal. The dual-frequency signal is specifically two positioning signals with different frequencies and orthogonal to each other. The dual-frequency signal is used to form a dual-frequency orthogonal signal emitted by the LED light source. For example, the power of the LED light source P = 3W, and the frequencies of the two positioning signals of the dual-frequency orthogonal signals of the 16 LED light sources are:

[0092] f11=1MHZ, f21=9MHZ f19=17MHZ, f29=25MHZ

[0093] f12=2MHZ,f22=10MHZ f1 10 =18MHZ, f2 10 =26MHZ

[0094] f13=3MHZ,f23=11MHZ f1 11 =19MHZ, f2111=27MHZ

[0095] f14=4MHZ,f24=12MHZ f1 12 =20MHZ, f2 12 =28MHZ

[0096] f15=5MHZ,f25=13MHZ f1 13 =21MHZ,f2 13 =29MHZ

[0097] f16=6MHZ,f26=14MHZ f1 14 =22MHZ, f2 14 =30MHZ

[0098] f17=7MHZ,f27=15MHZ f1 15 =23MHZ,f2 15 =31MHZ

[0099] f18=8MHZ,f28=16MHZ f1 16 =24MHZ,f2 16 =32MHZ

[0100] Among them, the dual-frequency orthogonal beacon can be expressed as:

[0101]

[0102] In the formula, x i0 represents a dual-frequency orthogonal beacon, sin(2πf 1 i t) represents the positioning signal 1, sin(2πf 2 i t) represents positioning signal 2, f1 i and f2 i They respectively represent the frequencies of the two positioning signals of the dual-frequency orthogonal beacon emitted by the i-th LED light source, wherein the frequencies of the two signals of the orthogonal beacon emitted by 16 LED light sources are as shown above.

[0103] Specifically, the method for generating the positioning signal can be: the positioning signal 1 can generate a corresponding frequency f1 through DDS iThe wave table of the sinusoidal signal is stored in the read-only memory (ROM). The positioning signal 2 can also be generated by DDS with a corresponding frequency of f2 i The wave table of the sinusoidal signal that is orthogonal to the positioning signal 1 is stored in a read-only memory (ROM). Since the frequencies of the positioning signal 1 and the positioning signal 2 are known, the emission period (T=1 / f) of the positioning signal 1 and the positioning signal 2 can be determined. In this way, when the light source is emitted, the dimmer of each LED light source will read its own positioning beacon 1 and positioning beacon 2 from its own ROM, and make the LED light source emit a dual-frequency orthogonal beacon according to the corresponding emission period.

[0104] Step S12, performing a fast Fourier transform (FFT) on the currently received dual-frequency orthogonal beacon to obtain a frequency spectrum diagram of the dual-frequency orthogonal beacon.

[0105] Step S13: converting the frequency spectrum of the dual-frequency orthogonal beacon into a phase-frequency diagram, and obtaining the phase values ​​of the two positioning signals of the dual-frequency orthogonal beacon at corresponding frequencies from the phase-frequency diagram of the dual-frequency orthogonal beacon.

[0106] Step S14: Calculate the differential phase of the dual-frequency orthogonal beacon according to the phase values ​​of the two positioning signals of the dual-frequency orthogonal beacon at corresponding frequencies.

[0107] Wherein, the differential phase of the dual-frequency orthogonal beacon satisfies the following conditional formula:

[0108]

[0109] in, is the differential phase of the dual-frequency orthogonal beacon currently received from the i-th LED light source, and They are respectively the phase values ​​of the two positioning signals of the dual-frequency orthogonal beacon emitted by the i-th LED light source currently received at the corresponding frequencies.

[0110] Step S15: Calculate the time difference of the dual-frequency orthogonal beacon according to the differential phase of the dual-frequency orthogonal beacon, where the time difference of the dual-frequency orthogonal beacon is the reception time difference of two positioning signals of the dual-frequency orthogonal beacon.

[0111] The time difference of the dual-frequency orthogonal beacons satisfies the following conditional formula:

[0112]

[0113] Among them, Δt i f1 is the time difference of the dual-frequency orthogonal beacon currently received from the i-th LED light source, iand f2 i They are respectively the corresponding frequencies of the two positioning signals of the dual-frequency orthogonal beacon emitted by the i-th LED light source currently received.

[0114] Step S16, constructing a nonlinear least squares equation group according to the time difference of each of the dual-frequency orthogonal beacons and the coordinate information of each of the LED light sources.

[0115] Specifically, the nonlinear least squares equation system L is expressed as:

[0116]

[0117] In the formula, r i is the distance from the ith LED light source to the positioning terminal, r i＝ Δt i *c, Δt i is the time difference of the dual-frequency orthogonal beacon emitted by the i-th LED light source currently received, c is the speed of light, Tx i , Ty i , Tz i represents the coordinates of the ith LED light source, and Rx, Ry, and Rz represent the position coordinates of the positioning terminal to be solved in the positioning area.

[0118] Step S17, linearly transform the nonlinear least squares equations to obtain a linear least squares equation (expressed as B=AX), and convert the linear least squares equation into a matrix form to obtain a least squares equation in matrix form.

[0119] Among them, the linear least squares equation system L' is expressed as:

[0120]

[0121] Among them, the least squares equation system L" in matrix form is expressed as:

[0122]

[0123] Among them, B=AX.

[0124] Step S18: Based on the preset solution constraints, a convex optimization algorithm is used to solve the least squares equations in the matrix form to obtain the position coordinates of the positioning terminal in the positioning area.

[0125] The solving constraint condition includes the coordinates of each vertex of the positioning area, that is, the coordinates of the positioning terminal finally solved should be within the range defined by the coordinates of each vertex of the positioning area. For example, but not limitation, the positioning area is a 10m × 10m × 10m three-dimensional space, and the positioning area has a total of eight vertex coordinates, then:

[0126] The x-axis positioning area constraint range is: 0≤Rx≤10;

[0127] The positioning area constraint range of the y-axis is: 0≤Ry≤10;

[0128] The positioning area constraint range of the z-axis is: 0≤Rz≤10, so as to solve the position constraint of the positioning terminal.

[0129] In order to verify the accuracy of the indoor visible light positioning solution in this embodiment, the positioning terminal can be placed in advance at the known coordinate position K in the positioning area, and then the position coordinates of the positioning terminal are calculated by the visible light positioning method based on dual-frequency orthogonal beacons in this embodiment, and then the calculated position coordinates of the positioning terminal are compared with the known coordinates of position K to determine the positioning error. Experimental verification shows that the visible light positioning solution in this embodiment, in a three-dimensional space area with a length, width and height of 10 meters, 10 meters and 10 meters respectively, 16 LEDs with an illumination power of P = 3W can achieve a positioning accuracy of 1.5cm under 30dB noise, which is very close to the theoretical limit.

[0130] Embodiment 3

[0131] Another aspect of the present invention is to provide a visible light positioning device based on a dual-frequency orthogonal beacon, see Figure 4 , applied to a positioning terminal, and used to locate the position of the positioning terminal in a preset positioning area indoors, wherein a plurality of LED light sources are arranged indoors, and the LED light sources can periodically transmit a dual-frequency orthogonal beacon to the positioning area in a pulse form, wherein the dual-frequency orthogonal beacon includes two positioning signals of different frequencies and orthogonal to each other, and the visible light positioning device based on the dual-frequency orthogonal beacon includes:

[0132] A signal receiving module 11 is used to receive the dual-frequency orthogonal beacon emitted by the LED light source, and calculate the differential phase of each dual-frequency orthogonal beacon currently received, where the differential phase of the dual-frequency orthogonal beacon is the phase difference between the two positioning signals of the dual-frequency orthogonal beacon;

[0133] A time difference calculation module 12, configured to calculate the time difference of the dual-frequency orthogonal beacon according to the differential phase of the dual-frequency orthogonal beacon, wherein the time difference of the dual-frequency orthogonal beacon is the reception time difference of two positioning signals of the dual-frequency orthogonal beacon;

[0134] The positioning module 13 is used to calculate the position coordinates of the positioning terminal in the positioning area according to the time difference of each of the dual-frequency orthogonal beacons and the coordinate information of each of the LED light sources.

[0135] Furthermore, in some optional embodiments of the present invention, the signal receiving module 11 includes:

[0136] A Fourier transform unit, configured to perform a fast Fourier transform on the currently received dual-frequency orthogonal beacon to obtain a frequency spectrum of the dual-frequency orthogonal beacon;

[0137] A spectrum conversion unit, used to convert the spectrum diagram of the dual-frequency orthogonal beacon into a phase-frequency diagram, and obtain the phase values ​​of the two positioning signals of the dual-frequency orthogonal beacon at corresponding frequencies from the phase-frequency diagram of the dual-frequency orthogonal beacon;

[0138] The differential calculation unit is used to calculate the differential phase of the dual-frequency orthogonal beacon according to the phase values ​​of the two positioning signals of the dual-frequency orthogonal beacon at corresponding frequencies.

[0139] Further, in some optional embodiments of the present invention, the differential phase of the dual-frequency orthogonal beacon satisfies the following conditional formula:

[0140]

[0141] in, is the differential phase of the dual-frequency orthogonal beacon currently received from the i-th LED light source, and They are respectively the phase values ​​of the two positioning signals of the dual-frequency orthogonal beacon emitted by the i-th LED light source currently received at the corresponding frequencies.

[0142] Further, in some optional embodiments of the present invention, the time difference of the dual-frequency orthogonal beacon satisfies the following conditional formula:

[0143]

[0144] Among them, Δt i f1 is the time difference of the dual-frequency orthogonal beacon currently received from the i-th LED light source, i and f2 i They are respectively the corresponding frequencies of the two positioning signals of the dual-frequency orthogonal beacon emitted by the i-th LED light source currently received.

[0145] Furthermore, in some optional embodiments of the present invention, the positioning module 13 includes:

[0146] An equation group construction unit, used to construct a nonlinear least squares equation group according to the time difference of each of the dual-frequency orthogonal beacons and the coordinate information of each of the LED light sources;

[0147] The coordinate solving unit is used to solve the nonlinear least squares equation group by using a convex optimization algorithm to obtain the position coordinates of the positioning terminal in the positioning area.

[0148] Furthermore, in some optional embodiments of the present invention, the coordinate solving unit is further used for:

[0149] Performing a linear transformation on the nonlinear least squares equation system to obtain a linear least squares equation system, and converting the linear least squares equation system into a matrix form to obtain a least squares equation system in matrix form;

[0150] Based on the preset solution constraints, a convex optimization algorithm is used to solve the least squares equations in the matrix form to obtain the position coordinates of the positioning terminal in the positioning area;

[0151] The constraint conditions to be solved include the coordinates of each vertex in the positioning area.

[0152] Further, in some optional embodiments of the present invention, the nonlinear least squares equation system L is expressed as:

[0153]

[0154] In the formula, r i is the distance from the ith LED light source to the positioning terminal, r i＝ Δt i *c, Δt i is the time difference of the dual-frequency orthogonal beacon emitted by the i-th LED light source currently received, c is the speed of light, Tx i , Ty i , Tz i represents the coordinates of the i-th LED light source, Rx, Ry, and Rz represent the position coordinates of the positioning terminal to be solved in the positioning area;

[0155] Among them, the linear least squares equation system L' is expressed as:

[0156]

[0157] Among them, the least squares equation system L" in matrix form is expressed as:

[0158]

[0159] Among them, B=AX.

[0160] The functions or operation steps implemented when the above modules and units are executed are generally the same as those in the above method embodiments, and will not be repeated here.

[0161] Embodiment 4

[0162] The fourth embodiment of the present invention further proposes a visible light positioning system based on dual-frequency orthogonal beacons, and the visible light positioning system based on dual-frequency orthogonal beacons includes:

[0163] A positioning network device is arranged indoors, the positioning network device comprises a plurality of LED light sources, the LED light sources can periodically transmit a dual-frequency orthogonal beacon to a preset positioning area indoors in a pulse form, the dual-frequency orthogonal beacon comprises two positioning signals of different frequencies and orthogonal to each other;

[0164] A positioning terminal is arranged indoors, and the positioning terminal includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the visible light positioning method based on the dual-frequency orthogonal beacon as described above is implemented to locate the position of the positioning terminal in the positioning area based on the dual-frequency orthogonal beacon emitted by the LED light source.

[0165] In some embodiments, the processor can be a central processing unit (CPU), a controller, a microcontroller, a microprocessor or other data processing chip, which is used to run the program code stored in the memory or process data, such as executing a visible light positioning program based on a dual-frequency orthogonal beacon.

[0166] Among them, the memory includes at least one type of readable storage medium, and the readable storage medium includes flash memory, hard disk, multimedia card, card-type memory (for example, SD or DX memory, etc.), magnetic memory, disk, optical disk, etc. In some embodiments, the memory can be an internal storage unit of the positioning terminal, such as the hard disk of the positioning terminal. In other embodiments, the memory can also be an external storage device of the positioning terminal, such as a plug-in hard disk equipped on the positioning terminal, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), etc. Further, the memory can also include both an internal storage unit and an external storage device of the positioning terminal. The memory can be used not only to store application software and various types of data installed in the positioning terminal, but also to temporarily store data that has been output or is to be output.

[0167] An embodiment of the present invention further provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the visible light positioning method based on dual-frequency orthogonal beacons as described above.

[0168] Those skilled in the art will appreciate that the logic and / or steps represented in the flowchart or otherwise described herein, for example, may be considered as an ordered list of executable instructions for implementing logical functions, and may be embodied in any computer-readable storage medium for use by an instruction execution system, device, or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device, or apparatus and execute instructions), or in conjunction with such instruction execution systems, devices, or apparatuses. For purposes of this specification, a "computer-readable storage medium" may be any device that can contain, store, communicate, propagate, or transmit a program for use by an instruction execution system, device, or apparatus, or in conjunction with such instruction execution systems, devices, or apparatuses.

[0169] More specific examples of computer-readable storage media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk case (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), a fiber optic device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable storage medium may even be a paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering or processing in another suitable manner as necessary, and then stored in a computer memory.

[0170] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or a combination thereof: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0171] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0172] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A visible light positioning method based on dual-frequency orthogonal beacons, characterized in that: The method is applied to a positioning terminal and used to locate the position of the positioning terminal in a preset positioning area indoors. A plurality of LED light sources are arranged indoors. The LED light sources can periodically transmit a dual-frequency orthogonal beacon to the positioning area in a pulse form. The dual-frequency orthogonal beacon includes two positioning signals of different frequencies and orthogonality. The method includes: Receive the dual-frequency orthogonal beacon emitted by the LED light source, and calculate the differential phase of each dual-frequency orthogonal beacon currently received, where the differential phase of the dual-frequency orthogonal beacon is the phase difference between the two positioning signals of the dual-frequency orthogonal beacon; Calculating the time difference of the dual-frequency orthogonal beacon according to the differential phase of the dual-frequency orthogonal beacon, where the time difference of the dual-frequency orthogonal beacon is the reception time difference of two positioning signals of the dual-frequency orthogonal beacon; Calculate the position coordinates of the positioning terminal in the positioning area according to the time difference of each of the dual-frequency orthogonal beacons and the coordinate information of each of the LED light sources; The step of calculating the position coordinates of the positioning terminal in the positioning area according to the time difference of each of the dual-frequency orthogonal beacons and the coordinate information of each of the LED light sources comprises: Constructing a nonlinear least squares equation group according to the time difference of each of the dual-frequency orthogonal beacons and the coordinate information of each of the LED light sources; Using a convex optimization algorithm to solve the nonlinear least squares equations to obtain the position coordinates of the positioning terminal in the positioning area; The step of using a convex optimization algorithm to solve the nonlinear least squares equations to obtain the position coordinates of the positioning terminal in the positioning area includes: Performing a linear transformation on the nonlinear least squares equation system to obtain a linear least squares equation system, and converting the linear least squares equation system into a matrix form to obtain a least squares equation system in matrix form; Based on the preset solution constraints, a convex optimization algorithm is used to solve the least squares equations in the matrix form to obtain the position coordinates of the positioning terminal in the positioning area; The constraint conditions to be solved include the coordinates of each vertex in the positioning area.

2. The visible light positioning method based on dual-frequency orthogonal beacons according to claim 1, characterized in that: The steps of calculating the differential phase of each dual-frequency orthogonal beacon currently received include: Performing a fast Fourier transform on the currently received dual-frequency orthogonal beacon to obtain a frequency spectrum of the dual-frequency orthogonal beacon; Converting the frequency spectrum of the dual-frequency orthogonal beacon into a phase-frequency diagram, and obtaining the phase values ​​of the two positioning signals of the dual-frequency orthogonal beacon at corresponding frequencies from the phase-frequency diagram of the dual-frequency orthogonal beacon; The differential phase of the dual-frequency orthogonal beacon is calculated according to the phase values ​​of the two positioning signals of the dual-frequency orthogonal beacon at corresponding frequencies.

3. The visible light positioning method based on dual-frequency orthogonal beacons according to claim 2 is characterized in that: The differential phase of the dual-frequency orthogonal beacon satisfies the following conditional formula: in, is the differential phase of the dual-frequency orthogonal beacon currently received from the i-th LED light source, and They are respectively the phase values ​​of the two positioning signals of the dual-frequency orthogonal beacon emitted by the i-th LED light source currently received at the corresponding frequencies.

4. The visible light positioning method based on dual-frequency orthogonal beacons according to claim 3 is characterized in that: The time difference of the dual-frequency orthogonal beacon satisfies the following conditional formula: Among them, Δt i is the time difference of the dual-frequency orthogonal beacon currently received from the i-th LED light source, and They are respectively the corresponding frequencies of the two positioning signals of the dual-frequency orthogonal beacon emitted by the i-th LED light source currently received.

5. The visible light positioning method based on dual-frequency orthogonal beacons according to claim 1, characterized in that: The nonlinear least squares equation system L is expressed as: In the formula, r i is the distance from the ith LED light source to the positioning terminal, r i＝ Δt i *c, Δt i is the time difference of the dual-frequency orthogonal beacon emitted by the i-th LED light source currently received, c is the speed of light, Tx i , Ty i , Tz i represents the coordinates of the i-th LED light source, Rx, Ry, and Rz represent the position coordinates of the positioning terminal to be solved in the positioning area; Among them, the linear least squares equation system L' is expressed as: Among them, the least squares equation system L" in matrix form is expressed as: Among them, B=AX.

6. A visible light positioning device based on dual-frequency orthogonal beacons, characterized in that: The device is used to implement the visible light positioning method based on dual-frequency orthogonal beacons as claimed in claim 1, and is applied to a positioning terminal to locate the position of the positioning terminal in a preset positioning area indoors, wherein a plurality of LED light sources are arranged indoors, and the LED light sources can periodically transmit dual-frequency orthogonal beacons to the positioning area in a pulse form, wherein the dual-frequency orthogonal beacons include two positioning signals with different frequencies and orthogonal to each other, and the device includes: A signal receiving module, used to receive the dual-frequency orthogonal beacon emitted by the LED light source, and calculate the differential phase of each dual-frequency orthogonal beacon currently received, where the differential phase of the dual-frequency orthogonal beacon is the phase difference between the two positioning signals of the dual-frequency orthogonal beacon; A time difference calculation module, used to calculate the time difference of the dual-frequency orthogonal beacon according to the differential phase of the dual-frequency orthogonal beacon, where the time difference of the dual-frequency orthogonal beacon is the reception time difference of two positioning signals of the dual-frequency orthogonal beacon; The positioning module is used to calculate the position coordinates of the positioning terminal in the positioning area according to the time difference of each of the dual-frequency orthogonal beacons and the coordinate information of each of the LED light sources.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the visible light positioning method based on dual-frequency orthogonal beacons as described in any one of claims 1 to 5 is implemented.

8. A visible light positioning system based on dual-frequency orthogonal beacons, characterized in that: The visible light positioning system based on dual-frequency orthogonal beacons includes: A positioning network device is arranged indoors, the positioning network device comprises a plurality of LED light sources, the LED light sources can periodically transmit a dual-frequency orthogonal beacon to a preset positioning area indoors in a pulse form, the dual-frequency orthogonal beacon comprises two positioning signals of different frequencies and orthogonal to each other; A positioning terminal is arranged indoors, and the positioning terminal includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the visible light positioning method based on dual-frequency orthogonal beacons as described in any one of claims 1 to 5 is implemented, so as to locate the position of the positioning terminal in the positioning area based on the dual-frequency orthogonal beacons emitted by the LED light source.

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