Positioning method and system based on visible light communication technology

Abstract

The invention provides a positioning method and system based on a visible light communication technology, and particularly relates to the technical field of indoor visible light positioning. According to the method, a plurality of visible light emitters emit modulated light signals, the modulated light signals are received by a prismatic table phased array receiving terminal, the terminal is provided with a plurality of receiving surfaces, and each receiving surface comprises a plurality of light detection units. And multi-stage differential noise reduction processing is carried out on the electric signals output by the light detection units of the receiving surfaces, the multi-stage differential noise reduction processing comprises first-stage differential suppression of local noise in the receiving surfaces and second-stage differential suppression of reflected light interference between the receiving surfaces, and a light intensity response value is obtained. The distance between the terminal and each transmitter is calculated through filtering processing and a distance calculation model based on a light intensity response value, and then the position of the terminal is determined by using a multilateral positioning algorithm, so that centimeter-level precision positioning in an electromagnetic sensitive environment is realized, and electromagnetic interference and explosion-proof risks are avoided.

Description

Technical Field

[0001] This invention relates to the field of indoor visible light positioning technology, and more specifically, to a positioning method and system based on visible light communication technology. Background Technology

[0002] With the widespread application of intelligent devices such as mobile robots and drones in industrial production and daily life, the requirements for their location awareness capabilities are increasing, especially in special or harsh environments such as large commercial buildings, underground parking lots, petrochemical plants, coal mines, and explosives production (where there is strong electromagnetic interference, stringent electromagnetic compatibility requirements, or explosion-proof requirements). However, in these specific scenarios, traditional positioning technologies that rely on electromagnetic waves (such as GNSS satellite signals, UWB, WiFi, RFID, etc.) face significant challenges: electromagnetic signals are extremely susceptible to interference and attenuation, and may even cause safety accidents due to electrical sparks, leading to positioning failure or a significant decrease in accuracy, which greatly limits the application scope and reliability of intelligent devices. To achieve positioning in the aforementioned special environments, existing technologies mainly rely on the aforementioned electromagnetic wave solutions (GNSS / UWB, etc.). However, these solutions have inherent limitations in applications under strong interference, explosion-proof, or harsh electromagnetic environments. While these technologies (such as UWB) can provide high accuracy in open environments, in the aforementioned special scenarios, solving electromagnetic interference and explosion-proof issues often requires complex electromagnetic shielding designs, the selection of expensive explosion-proof certification equipment, or the deployment of additional signal enhancement infrastructure. This not only significantly increases system costs and maintenance difficulty, but also makes it difficult to guarantee positioning performance or even completely fail in certain extreme environments (such as near strong interference sources or inside enclosed metal structures), thus failing to meet application requirements. In summary, a pressing technical problem is how to achieve stable and high-precision positioning of intelligent devices in special application environments with strong electromagnetic interference, stringent electromagnetic compatibility restrictions, or explosion-proof requirements, without relying on electromagnetic wave signals and overcoming ambient light noise and multipath reflection interference. Summary of the Invention

[0003] The main objective of this invention is to provide a positioning method and system based on visible light communication technology, which at least solves the technical problem of how to achieve stable and high-precision positioning of intelligent devices in special application environments with strong electromagnetic interference, strict electromagnetic compatibility restrictions, or explosion-proof requirements, without relying on electromagnetic wave signals and overcoming ambient light noise and multipath reflection interference. Through visible light communication and multi-level noise-resistant hardware collaboration, centimeter-level precision positioning can be stably achieved in electromagnetically sensitive environments, completely avoiding electromagnetic interference and explosion-proof risks.

[0004] To achieve the above objectives, the present invention provides a positioning method and system based on visible light communication technology.

[0005] In a first aspect, the present invention provides a positioning method based on visible light communication technology, the method comprising: Modulated light signals are emitted through multiple visible light emitters; The modulated optical signal is received by a truncated phased array receiving terminal, which has multiple receiving surfaces, each of which contains multiple optical detection units. The electrical signals output by multiple optical detection units on each receiving surface are subjected to multi-level differential noise reduction processing to obtain the light intensity response value of each receiving surface. The multi-level differential noise reduction processing includes performing first-level differential processing among multiple optical detection units within the receiving surface to suppress local noise, and performing second-level differential processing among multiple receiving surfaces to suppress reflected light interference. Based on the light intensity response values ​​of the multiple receiving surfaces, the distance between the prism phased array receiving terminal and each visible light emitter is calculated through filtering and a distance calculation model. Based on the distance, the location of the prism phased array receiving terminal is determined using a polygonal positioning algorithm.

[0006] Specifically, the transmission of modulated optical signals through multiple visible light emitters includes: Orthogonal frequency division multiplexing (OFDM) technology is used to map digital signals onto multiple subcarriers to generate modulated signals; A DC bias current is superimposed on the modulation signal to drive the visible light transmitter to output a modulated light signal containing positioning information.

[0007] Specifically, the modulated optical signal is received via a truncated phased array receiving terminal. The truncated phased array receiving terminal has multiple receiving surfaces, each containing multiple optical detection units, including: Five receiving surfaces with normal vector directions of (±1,0,0), (0,±1,0), and (0,0,1) are set up. A 9×9 array of light detection units is arranged on each receiving surface, and the photosensitive area of ​​a single light detection unit is 5mm×5mm.

[0008] Specifically, the step of performing multi-level differential noise reduction processing on the electrical signals output by the multiple optical detection units of each receiving surface to obtain the light intensity response value of each receiving surface includes: The maximum value of the output voltage of 81 photodetectors within a single receiving surface is selected to obtain the candidate response value of that receiving surface; The candidate response values ​​of the five receiving surfaces are input into a programmable gain amplifier, and the difference signals between the receiving surfaces are amplified before the light intensity response value is output.

[0009] Specifically, the calculation of the distance between the prism phased array receiving terminal and each visible light emitter based on the light intensity response values ​​of the plurality of receiving surfaces, through filtering and a distance calculation model, includes: The Kalman filter algorithm is used to iteratively correct the historical error of the light intensity response value. The corrected light intensity response value is input into the light attenuation model. Based on the reference light intensity of the pre-calibrated visible light emitter at the reference distance, the distance between the prism phased array receiving terminal and each visible light emitter is calculated.

[0010] Specifically, determining the position of the prism phased array receiving terminal using a multilateral positioning algorithm based on the distance includes: Establish a system of spherical equations with the positions of each visible light emitter as centers and the corresponding distances as radii; The position of the prism phased array receiving terminal is output by solving the three-dimensional coordinate solution that satisfies the error threshold through an iterative optimization algorithm.

[0011] Specifically, the step of inputting the candidate response values ​​of the five receiving surfaces into a programmable gain amplifier, amplifying the difference signals between the receiving surfaces, and then outputting the light intensity response value includes: The gain coefficient of the programmable gain amplifier is dynamically adjusted by a microcontroller. The light intensity response value is generated by amplifying the difference between the candidate response value of the current receiving surface and the average of the candidate response values ​​of the other receiving surfaces based on the gain coefficient.

[0012] In a second aspect, the present invention provides a positioning system based on visible light communication technology, wherein the positioning system applies the positioning method described in the first aspect, and the positioning system includes: Visible light emitting module, used to emit modulated light signals through multiple visible light emitters; A truncated phased array receiving module is connected to the visible light emitting module for optical signal transmission. The truncated phased array receiving module is used to receive the modulated optical signal. The truncated phased array receiving module has multiple receiving surfaces, and each receiving surface contains multiple optical detection units. A multi-level differential noise reduction module is electrically connected to the prism phased array receiving module. The multi-level differential noise reduction module is used to perform multi-level differential noise reduction processing on the electrical signals output by multiple photodetectors on each receiving surface to generate the light intensity response value of each receiving surface. The multi-level differential noise reduction processing includes performing first-level differential processing between multiple photodetectors on the receiving surface to suppress local noise, and performing second-level differential processing between multiple receiving surfaces to suppress reflected light interference. The distance calculation module is connected to the multi-level differential noise reduction module. The distance calculation module is used to calculate the distance between the prism phased array receiving module and each visible light emitter based on the light intensity response value through filtering and distance calculation model. The positioning output module is connected to the distance calculation module. The positioning output module is used to determine the position coordinates of the prism phased array receiving module based on the distance using a polygonal positioning algorithm.

[0013] Specifically, the visible light emitting module includes: An orthogonal frequency division multiplexing unit is used to map digital signals onto multiple subcarriers to generate modulated signals; A DC bias drive unit is electrically connected to the orthogonal frequency division multiplexing unit. The DC bias drive unit is used to superimpose a DC bias current on the modulation signal to drive the visible light transmitter to output a modulated light signal containing positioning information.

[0014] Specifically, the prism phased array receiving module includes: The pentahedral receiving architecture has five receiving surfaces with normal vector directions of (±1,0,0), (0,±1,0), and (0,0,1), respectively. An array-type light detection unit group is integrated into each receiving surface of the pentahedral receiving architecture. The array-type light detection unit group consists of a 9×9 array of light detection units, and the photosensitive area of ​​a single light detection unit is 5mm×5mm.

[0015] The positioning method and system based on visible light communication technology provided in this application can be applied to special environments with strong electromagnetic interference, strict electromagnetic compatibility restrictions, or explosion-proof requirements. This method utilizes multiple visible light transmitters to emit modulated light signals, which are received by a truncated phased array receiving terminal with multiple receiving surfaces, each containing multiple photodetector units. Multi-level differential noise reduction processing is performed on the electrical signals output by the photodetector units of each receiving surface; specifically, a first-level differential noise reduction is performed between the multiple photodetector units within the receiving surface to suppress local noise, and a second-level differential noise reduction is performed between the multiple receiving surfaces to suppress reflected light interference, resulting in a light intensity response value. Based on this response value, the distance between the terminal and each transmitter is calculated using a filtering and distance calculation model. Then, a polygonal positioning algorithm is used to determine the terminal's position, achieving centimeter-level accuracy positioning in electromagnetically sensitive environments while avoiding electromagnetic interference and explosion-proof risks. Attached Figure Description

[0016] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 A flowchart illustrating the positioning method based on visible light communication technology provided in this application; Figure 2 A connection diagram of the positioning system based on visible light communication technology provided in this application.

[0017] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0019] The terms "first," "second," "third," "fourth," etc. (if present) in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein.

[0020] In this invention, the terms "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0021] This application provides a positioning method and system based on visible light communication technology. The technical concept of this positioning method revolves around positioning based on visible light communication technology. In special application environments with challenges such as strong electromagnetic interference, multiple visible light transmitters emit modulated light signals, which are received by a prism phased array receiving terminal with multiple receiving surfaces, each containing multiple light detection units. The received electrical signals undergo multi-stage differential noise reduction processing to suppress local noise and reflected light interference, obtaining the light intensity response value. After filtering and distance calculation using a distance calculation model, the distance is calculated. Finally, a polygonal positioning algorithm is used to determine the terminal's position, achieving centimeter-level accuracy positioning in electromagnetically sensitive environments.

[0022] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0023] Figure 1 A flowchart illustrating the positioning method based on visible light communication technology provided in this application is shown below. Figure 1 As shown, this embodiment provides a positioning method based on visible light communication technology, which includes: S101: A modulated light signal is emitted by multiple visible light emitters and received by a prism phased array receiving terminal. The prism phased array receiving terminal has multiple receiving surfaces, and each receiving surface contains multiple light detection units.

[0024] Specifically, the transmission of modulated optical signals through multiple visible light emitters includes: Orthogonal frequency division multiplexing (OFDM) technology is used to map digital signals onto multiple subcarriers to generate modulated signals; A DC bias current is superimposed on the modulation signal to drive the visible light transmitter to output a modulated light signal containing positioning information.

[0025] Specifically, the modulated optical signal is received via a truncated phased array receiving terminal. The truncated phased array receiving terminal has multiple receiving surfaces, each containing multiple optical detection units, including: Five receiving surfaces with normal vector directions of (±1,0,0), (0,±1,0), and (0,0,1) are set up. A 9×9 array of light detection units is arranged on each receiving surface, and the photosensitive area of ​​a single light detection unit is 5mm×5mm.

[0026] The specific steps of implementation S101 include: 1. Implementation of Visible Light Signal Transmission 1.1 Orthogonal Frequency Division Multiplexing Modulation: 1.1.1 Using an OFDM modulator, the positioning digital signal (containing device ID and timestamp information) is mapped onto 16 subcarriers.

[0027] 1.1.1.1 Modulation parameters: Number of subcarriers: 16 Subcarrier spacing: 312.5 kHz Modulation method: QPSK (Quadrature Phase Shift Keying) 1.1.1.2 Modulation signal generation formula:

[0028] in: : The QPSK modulation symbol of the kth subcarrier (with values ​​of ±1±j); : The frequency of the kth subcarrier ( =k×312.5kHz).

[0029] 1.2 DC bias drive: 1.2.1 Processing the modulated signal using a constant current drive circuit: OFDM modulated signal Input voltage-to-current converter to generate AC current component .

[0030] Superimposed DC bias current This ensures that the LED operates in the linear region.

[0031] Drive the white LED beads to output the final light signal:

[0032] in This is a normalized modulated signal (amplitude ±1).

[0033] 2. Implementation of the Prism Phased Array Receiving Terminal 2.1 Construction of the pentahedral structure: 2.1.1 An aluminum alloy frustum frame is used: Base dimensions: 10 cm × 10 cm; Top surface: 5 cm × 5 cm; Height: 8 cm.

[0034] 2.1.2 Directions of the normal vectors of the five receiving surfaces: Front: Normal vector (1,0,0); Follower: Normal vector (-1, 0, 0); Left side: Normal vector (0, -1, 0); Right side: Normal vector (0,1,0); Top surface: Normal vector (0,0,1).

[0035] 2.2 Deployment of the optical detection unit array: 2.2.1 Each receiving surface is equipped with a silicon photovoltaic array board (PCB substrate): 2.2.1.1 Array structure: 9 rows × 9 columns, with a total of 81 optical detection units; 2.2.1.2 Cell Model: Hamamatsu S1133 Silicon Photovoltaic Cell Photosensitive area size: 5 mm × 5 mm; Response wavelength: 400–1100 nm; Peak sensitivity: 0.5 A / W (@525 nm).

[0036] 2.2.2 Photoelectric conversion circuit: Each silicon photovoltaic cell is connected to a transimpedance amplifier (OPA2335 op-amp); Feedback resistor Gain ≈ 40 dB; Output voltage: ( (Photocurrent).

[0037] 3. Setting up the signal receiving environment 3.1 Test Scenario: Space dimensions: 6 m long × 3 m wide × 1.5 m high (simulating an underground parking environment); LED layout: A 3×3 LED array is installed on the ceiling with a spacing of 2 m.

[0038] 3.2 Installation of the receiving terminal: Fixed to the top of the mobile robot, at a height of 0.8 m; Signals from five receiving surfaces are simultaneously acquired using a microcontroller (main control chip).

[0039] This step achieves interference-resistant optical signal transmission through OFDM modulation and DC bias drive, ensuring stable transmission of positioning information under strong ambient light. The hardware design, using a pentahedral truncated pyramid structure and a 9×9 silicon photodiode array, enables omnidirectional optical signal capture in three-dimensional space, solving the signal loss problem caused by device rotation in traditional planar receivers. Actual measurements show that under 1000 lux ambient light interference, the signal-to-noise ratio of this receiver is improved to 35 dB (15 dB higher than a single-sided receiver), providing a high-quality input signal for subsequent noise reduction processing.

[0040] S102: Perform multi-level differential noise reduction processing on the electrical signals output by multiple optical detection units on each receiving surface to obtain the light intensity response value of each receiving surface.

[0041] The multi-level differential noise reduction process includes performing a first-level differential process among multiple optical detection units within the receiving surface to suppress local noise, and performing a second-level differential process among multiple receiving surfaces to suppress reflected light interference.

[0042] Specifically, the step of performing multi-level differential noise reduction processing on the electrical signals output by the multiple optical detection units of each receiving surface to obtain the light intensity response value of each receiving surface includes: The maximum value of the output voltage of 81 photodetectors within a single receiving surface is selected to obtain the candidate response value of that receiving surface; The candidate response values ​​of the five receiving surfaces are input into a programmable gain amplifier to amplify the difference signals between the receiving surfaces and output the light intensity response value. Specifically, the process of inputting the candidate response values ​​of the five receiving surfaces into a programmable gain amplifier to amplify the difference signals between the receiving surfaces and output the light intensity response value includes: dynamically adjusting the gain coefficient of the programmable gain amplifier through a microcontroller; and amplifying the difference between the candidate response value of the current receiving surface and the average of the candidate response values ​​of the other receiving surfaces according to the gain coefficient to generate the light intensity response value.

[0043] The specific steps of implementation S102 include: 1. First-level difference processing (in-plane maximum value filtering) 1.1 Filtering by maximum value within a plane: The maximum value of the output voltage of the 81 photodetectors in each receiving surface is filtered to output the candidate response value for that receiving surface:

[0044] Parameter definition: i: Receiver surface number (values ​​range from 1 to 5, corresponding to 5 receiver surfaces); : Output voltage of the nth photodetector unit in the i-th receiving surface (unit: volts V); : Candidate response value of the i-th receiving surface (unit: volts V).

[0045] 2. Second-order difference processing (amplification of inter-surface differences) 2.1 Amplification of difference signals: 2.1.1 For the currently processed receiving surface k (k=1,2,3,4,5), calculate the difference between its candidate response value and the mean of the candidate response values ​​of the other receiving surfaces:

[0046] The equivalent abbreviation is: .

[0047] 2.1.2 Amplification via a programmable gain amplifier: , where G represents the gain coefficient. Output: Light intensity response value of the k-th receiving surface (Unit: Volts V)

[0048] 3. Implementation of ambient light monitoring (optional) The formula for converting the resistance R of a photoresistor to the ambient light intensity E (lux) is modified as follows:

[0049] Parameter definition: R: Real-time resistance value measured by the photoresistor (unit: ohms Ω); =10,000Ω (calibrated under a standard light source of 1000 lux); =1,000,000Ω (calibrated in complete darkness).

[0050] This step achieves in-plane noise suppression (eliminating localized strong light interference) through a cascaded hardware comparator circuit, and addresses inter-plane reflected light interference using a dynamic gain amplifier. Actual measurements were taken under 1000 lux ambient light. 1. In-plane maximum value screening improves the local noise suppression rate to 90% (from 60%). 2. The difference amplification algorithm reduces the multipath reflection error from ±10 cm to ±2 cm; 3. Gain coefficient Adaptive adjustment ensures that the response consistency error is <±3% across scenarios ranging from coal mines (50 lux) to shopping malls (3000 lux).

[0051] 4. Innovation: The synergistic design of tree-like comparison structure (0.2 μs delay) and exponential gain adjustment provides anti-interference guarantee for high-precision positioning.

[0052] S103: Based on the light intensity response values ​​of the plurality of receiving surfaces, the distance between the prism phased array receiving terminal and each visible light transmitter is calculated through filtering and a distance calculation model.

[0053] Specifically, the calculation of the distance between the prism phased array receiving terminal and each visible light emitter based on the light intensity response values ​​of the plurality of receiving surfaces, through filtering and a distance calculation model, includes: The Kalman filter algorithm is used to iteratively correct the historical error of the light intensity response value. The corrected light intensity response value is input into the light attenuation model. Based on the reference light intensity of the pre-calibrated visible light emitter at the reference distance, the distance between the prism phased array receiving terminal and each visible light emitter is calculated.

[0054] The specific steps in step S103 during implementation include: 1. Kalman filter iterative correction 1.1 Input and Initialization: Input the 5 light intensity response values ​​in step S102: (Unit: Volts V) Set the initial state vector ; The observation matrix H = I (a 5×5 identity matrix).

[0055] 1.2 Kalman Filter Calculation: Parameter definition: : Current state estimation vector (dimension 5×1); Kalman gain matrix (5×5 matrix); : Error covariance matrix of the previous time step (initial value I); R: Observation noise covariance (diagonal matrix, element 0.01); : Current measurement vector (i.e. to ).

[0056] Output: Corrected light intensity value (k=1,2,…,5).

[0057] 2. Distance Calculation for Optical Attenuation Model 2.1 Distance calculation formula:

[0058] Parameter definition: : Distance from the receiving terminal to the k-th light source (unit: meters); Reference distance (calibrated value, 1.0 meter); : Temperature-compensated reference voltage (volts V, calculation below); : The corrected light intensity value of the k-th surface; Angle of incidence of light.

[0059] 2.2 Temperature Compensation: Thermistor measures ambient temperature T (unit: °C); Corrected reference voltage: .

[0060] in This is the reference voltage value calibrated at 25℃.

[0061] 2.3 Calculation of the angle of incidence: Receiver surface normal vector (as above) =(1,0,0)); Light source direction vector:

[0062] Component definition: : The three-dimensional coordinates (known position) of the k-th visible light emitter; : The three-dimensional coordinates of the center point of the prism phased array receiving terminal (target to be located).

[0063] Calculation after normalization: . This step uses Kalman filtering to dynamically correct the light intensity response value (suppressing historical error fluctuations of ±8%), and combines this with a temperature-compensated light attenuation model to calculate the distance. 1. Kalman gain matrix Real-time weight adjustment reduces multipath interference error by 40%; 2. Incident angle compensation Eliminate the ±12% ranging deviation caused by the tilt of the receiving surface; 3. Temperature correction factor −0.002 / °C ensures ranging error ≤±3% in environments ranging from -10℃ to 55℃.

[0064] Under ambient light interference of 1000 lux, the root mean square error of ranging is ≤2 cm, providing accurate input for 3D positioning.

[0065] S104: Based on the distance, determine the position of the prism phased array receiving terminal using a polygonal positioning algorithm.

[0066] Specifically, determining the position of the prism phased array receiving terminal using a multilateral positioning algorithm based on the distance includes: Establish a system of spherical equations with the positions of each visible light emitter as centers and the corresponding distances as radii; The position of the prism phased array receiving terminal is output by solving the three-dimensional coordinate solution that satisfies the error threshold through an iterative optimization algorithm.

[0067] The specific steps in step S104 during implementation include: 1. Establish the system of equations for the sphere 1.1 Input data preparation: Obtain the distance from the prism phased array receiving terminal to each visible light transmitter from step S103. (k=1,2,…,N, where N is the number of visible light emitters); Known three-dimensional coordinates of the visible light emitter: (Unit: meters).

[0068] 1.2 Construction of the spherical equation: Equations are established for each visible light emitter: Parameter definition: (x,y,z): The coordinates of the position to be determined for the phased array receiver terminal (unit: meters); ( ): The known coordinates (in meters) of the k-th visible light emitter; : Distance from the receiving terminal to the k-th light source (unit: meters).

[0069] 2. Iterative optimization solution 2.1 Definition of error function: Construct the least squares error function: .

[0070] 2.2 Optimize algorithm execution: Iterative optimization was performed using the L-BFGS algorithm (Finite Memory Quasi-Newton method): 2.2.1 Initialization: The average coordinates of all visible light emitters are used as the initial solution. .

[0071] 2.2.2 Iterative Updates: Calculate gradient : .

[0072] The solution is updated approximately using the Hessian matrix: ,in, Step size factor; It is an approximate Hessian matrix.

[0073] 2.2.3 Termination Conditions: When the coordinate change in two consecutive iterations is less than the error threshold Stop when =0.05m .

[0074] 2.3 Output positioning results: Final coordinates: . This step establishes an overdetermined spherical equation set (when the number of visible light transmitters is ≥4), and uses the L-BFGS optimization algorithm to solve for the three-dimensional coordinates of the receiving terminal. First, based on the distance data output by S103 and the known transmitter positions, a spatial geometric constraint equation is constructed. Then, the optimal position is solved through gradient calculation and iterative update. Finally, a positioning accuracy of ≤5 cm is achieved in a 3×3 transmitter layout (9 light sources), and it only takes an average of 2.3 iterations to converge to within the 0.05 m error threshold. This effectively overcomes multipath reflection interference and stably outputs centimeter-level positioning results in complex electromagnetic environments such as explosion-proof areas of petrochemical plants and underground parking lots.

[0075] This embodiment provides a positioning method based on visible light communication technology. In this method, multiple visible light transmitters emit modulated light signals, which are received by a prism phased array receiving terminal. This terminal has multiple receiving surfaces, each containing multiple photodetector units. Multi-level differential noise reduction processing is applied to the electrical signals output by the photodetector units of each receiving surface. First-level differential processing is performed between the multiple photodetector units within a receiving surface to suppress local noise; second-level differential processing is performed between the multiple receiving surfaces to suppress reflected light interference, thereby obtaining the light intensity response value of each receiving surface. Based on the light intensity response value, the distance between the prism phased array receiving terminal and each visible light transmitter is calculated using filtering and a distance calculation model. Then, a polygonal positioning algorithm is used to determine the terminal's position. This method, through the collaboration of visible light communication and multi-level noise-resistant hardware, can stably achieve centimeter-level accuracy positioning in electromagnetically sensitive environments, effectively avoiding electromagnetic interference and explosion-proof risks.

[0076] Figure 2 A connection diagram of the positioning system based on visible light communication technology provided in this application is shown below. Figure 2 As shown, this is a positioning system based on visible light communication technology provided in this embodiment. This system applies... Figure 1 The positioning method based on visible light communication technology described in the embodiment includes a positioning system comprising: Visible light emitting module, used to emit modulated light signals through multiple visible light emitters; A truncated phased array receiving module is connected to the visible light emitting module for optical signal transmission. The truncated phased array receiving module is used to receive the modulated optical signal. The truncated phased array receiving module has multiple receiving surfaces, and each receiving surface contains multiple optical detection units. A multi-level differential noise reduction module is electrically connected to the prism phased array receiving module. The multi-level differential noise reduction module is used to perform multi-level differential noise reduction processing on the electrical signals output by multiple photodetectors on each receiving surface to generate the light intensity response value of each receiving surface. The multi-level differential noise reduction processing includes performing first-level differential processing between multiple photodetectors on the receiving surface to suppress local noise, and performing second-level differential processing between multiple receiving surfaces to suppress reflected light interference. The distance calculation module is connected to the multi-level differential noise reduction module. The distance calculation module is used to calculate the distance between the prism phased array receiving module and each visible light emitter based on the light intensity response value through filtering and distance calculation model. The positioning output module is connected to the distance calculation module. The positioning output module is used to determine the position coordinates of the prism phased array receiving module based on the distance using a polygonal positioning algorithm.

[0077] Specifically, the visible light emitting module includes: An orthogonal frequency division multiplexing unit is used to map digital signals onto multiple subcarriers to generate modulated signals; A DC bias drive unit is electrically connected to the orthogonal frequency division multiplexing unit. The DC bias drive unit is used to superimpose a DC bias current on the modulation signal to drive the visible light transmitter to output a modulated light signal containing positioning information.

[0078] Specifically, the prism phased array receiving module includes: The pentahedral receiving architecture has five receiving surfaces with normal vector directions of (±1,0,0), (0,±1,0), and (0,0,1), respectively. An array-type light detection unit group is integrated into each receiving surface of the pentahedral receiving architecture. The array-type light detection unit group consists of a 9×9 array of light detection units, and the photosensitive area of ​​a single light detection unit is 5mm×5mm.

[0079] In practice, the positioning method system based on visible light communication technology provided in this embodiment specifically includes: 1. Implementation of the visible light emission module 1.1 Orthogonal Frequency Division Multiplexing Unit: The positioning digital signal is decomposed into 16 independent subcarriers, each subcarrier is modulated using quadrature phase shift keying, and the subcarrier spacing is fixed at 312.5 kHz to generate a composite modulated signal.

[0080] 1.2 DC bias drive unit: A 20 mA DC current is superimposed on the modulation signal to drive the white light-emitting diode to output a light signal, ensuring that the light-emitting diode operates in the linear light emission range.

[0081] 1.3 Module function: To avoid signal distortion and maintain complete transmission of positioning information under ambient light intensity of 1000 lux.

[0082] 2. Implementation of the Prism Phased Array Receiving Module 2.1 Pentahedral receiver architecture: The aluminum alloy frame forms a five-sided pyramid structure with a base side length of 10 cm, a top side length of 5 cm, and a vertical height of 8 cm. The normal vector directions of the five receiving surfaces are: positive X-axis direction, negative X-axis direction, negative Y-axis direction, positive Y-axis direction, and positive Z-axis direction.

[0083] 2.2 Array-type optical detection unit group: Each receiving surface is equipped with 81 silicon photovoltaic cell units, arranged at equal intervals in 9 rows and 9 columns; Each silicon photovoltaic cell has a photosensitive area of ​​5 mm × 5 mm square, and its spectral response range covers wavelengths from 400 nm to 1100 nm.

[0084] Each unit is connected to a transimpedance amplifier circuit with a feedback resistor of 10 kiloohms, realizing the conversion of photocurrent into voltage signal.

[0085] 2.3 Module Function: Through three-dimensional spatial layout, it solves the problem of signal interruption caused by equipment rotation.

[0086] 3. Implementation of multi-level differential noise reduction module 3.1 First-level differential processing unit: A tree-structured cascaded voltage comparison circuit is used to filter the maximum value of 81 voltage signals within a single receiving surface step by step, and output the candidate response value of the receiving surface to eliminate local strong light interference.

[0087] 3.2 Second-level differential processing unit: The programmable gain amplifier receives candidate response values ​​from five receiving surfaces; The microcontroller dynamically adjusts the amplifier gain coefficient based on the ambient light intensity value collected in real time by the photoresistor. The difference between the current candidate response value of the receiving surface and the average value of the other four surfaces is calculated, and the final light intensity response value is output after gain amplification.

[0088] 3.3 Module function: Suppress multipath reflection interference and reduce positioning error to 2 cm in shopping mall window environments.

[0089] 4. Implementation of the distance calculation module 4.1 Kalman Filter Unit: A state vector is constructed based on the light intensity response values ​​of the five receiving surfaces. The measurement error is iteratively corrected through a prediction-update process, and the diagonal elements of the observation noise covariance matrix are set to 0.01.

[0090] 4.2 Distance Calculation Unit: The received signal strength model is adopted, combined with the reference voltage value calibrated at 25 degrees Celsius; The ambient temperature is collected by a thermistor, and the reference voltage is compensated by a coefficient of -0.002 per degree Celsius. The distance from the terminal to each light source is calculated based on the cosine of the angle between the normal vector of the receiving surface and the direction of the light source.

[0091] 4.3 Function: To eliminate the influence of silicon photovoltaic cell temperature drift and maintain a ranging error of ≤3% in an environment ranging from -10 degrees Celsius to 55 degrees Celsius.

[0092] 5. Implementation of the positioning output module 5.1 Building blocks for the spherical equation system: Using the known three-dimensional coordinates of each light source as the center of a sphere and the distance value output by the distance calculation module as the radius, a spatial geometric constraint equation is established.

[0093] 5.2 L-BFGS Optimization Unit: Using the average coordinates of all light sources as the initial solution, the gradient of the objective function is calculated. The three-dimensional coordinate solution is iteratively updated using the quasi-Newton method. The calculation is terminated when the coordinate change in consecutive iterations is less than 0.05 meters, and the final position coordinates of the terminal are output.

[0094] Module 5.3 Function: Achieve centimeter-level positioning accuracy in metallic reflective environments, completing the calculation in an average of 2.3 iterations.

[0095] The specific connection relationships of the positioning method system based on visible light communication technology provided in this embodiment are as follows: 1. Optical transmission connection: Signals are transmitted between the light-emitting diodes of the visible light emitting module and the silicon photodiodes of the prism phased array receiving module via a free-space optical path.

[0096] 2. Circuit connection: The output of the silicon photovoltaic cell is connected to the input pin of the voltage comparator via copper foil traces on a printed circuit board. The output of the programmable gain amplifier is connected to the analog-to-digital converter interface of the microcontroller via a twisted pair cable.

[0097] 3. Data Interface: The distance calculation module and the positioning output module transmit distance data through a serial peripheral interface; The positioning coordinates are output to the host computer via a universal asynchronous transceiver interface.

[0098] This system addresses the signal reception blind zone issue through a pentahedral spatial layout, suppresses 90% of ambient light interference through a dynamic gain adjustment mechanism, controls ranging temperature drift error to within 3% using a temperature compensation model, and outputs centimeter-level positioning results within 10 milliseconds using the L-BFGS optimization algorithm. In actual testing in an explosion-proof area of ​​a petrochemical plant, it operated continuously for 500 hours without failure, with a maximum positioning trajectory deviation of no more than 5 centimeters, completely avoiding the risk of electromagnetic interference.

[0099] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the following claims.

[0100] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A positioning method based on visible light communication technology, characterized in that, The method includes: Modulated light signals are emitted through multiple visible light emitters; The modulated optical signal is received by a truncated phased array receiving terminal, which has multiple receiving surfaces, each of which contains multiple optical detection units. The electrical signals output by multiple optical detection units on each receiving surface are subjected to multi-level differential noise reduction processing to obtain the light intensity response value of each receiving surface. The multi-level differential noise reduction processing includes performing first-level differential processing among multiple optical detection units within the receiving surface to suppress local noise, and performing second-level differential processing among multiple receiving surfaces to suppress reflected light interference. Based on the light intensity response values ​​of the multiple receiving surfaces, the distance between the prism phased array receiving terminal and each visible light emitter is calculated through filtering and a distance calculation model. Based on the distance, the location of the prism phased array receiving terminal is determined using a polygonal positioning algorithm.

2. The positioning method based on visible light communication technology according to claim 1, characterized in that, The transmission of modulated optical signals via multiple visible light emitters includes: Orthogonal frequency division multiplexing (OFDM) technology is used to map digital signals onto multiple subcarriers to generate modulated signals; A DC bias current is superimposed on the modulation signal to drive the visible light transmitter to output a modulated light signal containing positioning information.

3. The positioning method based on visible light communication technology according to claim 1, characterized in that, The modulated optical signal is received via a truncated pyramid phased array receiving terminal, which has multiple receiving surfaces, each containing multiple optical detection units, including: Five receiving surfaces with normal vector directions of (±1,0,0), (0,±1,0), and (0,0,1) are set up. A 9×9 array of light detection units is arranged on each receiving surface, and the photosensitive area of ​​a single light detection unit is 5mm×5mm.

4. The positioning method based on visible light communication technology according to claim 1, characterized in that, The process of performing multi-level differential noise reduction on the electrical signals output by multiple optical detection units on each receiving surface to obtain the light intensity response value of each receiving surface includes: The maximum value of the output voltage of 81 photodetectors within a single receiving surface is selected to obtain the candidate response value of that receiving surface; The candidate response values ​​of the five receiving surfaces are input into a programmable gain amplifier, and the difference signals between the receiving surfaces are amplified before the light intensity response value is output.

5. The positioning method based on visible light communication technology according to claim 1, characterized in that, The calculation of the distance between the prism phased array receiving terminal and each visible light emitter based on the light intensity response values ​​of the multiple receiving surfaces, through filtering and a distance calculation model, includes: The Kalman filter algorithm is used to iteratively correct the historical error of the light intensity response value. The corrected light intensity response value is input into the light attenuation model. Based on the reference light intensity of the pre-calibrated visible light emitter at the reference distance, the distance between the prism phased array receiving terminal and each visible light emitter is calculated.

6. The positioning method based on visible light communication technology according to claim 1, characterized in that, The step of determining the position of the prism phased array receiving terminal using a multilateral positioning algorithm based on the distance includes: Establish a system of spherical equations with the positions of each visible light emitter as centers and the corresponding distances as radii; The position of the prism phased array receiving terminal is output by solving the three-dimensional coordinate solution that satisfies the error threshold through an iterative optimization algorithm.

7. The positioning method based on visible light communication technology according to claim 4, characterized in that, The step of inputting the candidate response values ​​of the five receiving surfaces into a programmable gain amplifier, amplifying the difference signals between the receiving surfaces, and then outputting the light intensity response value includes: The gain coefficient of the programmable gain amplifier is dynamically adjusted by a microcontroller. The light intensity response value is generated by amplifying the difference between the candidate response value of the current receiving surface and the average of the candidate response values ​​of the other receiving surfaces based on the gain coefficient.

8. A positioning system based on visible light communication technology, characterized in that, The positioning system employs the positioning method according to any one of claims 1-7, and the positioning system comprises: Visible light emitting module, used to emit modulated light signals through multiple visible light emitters; A truncated phased array receiving module is connected to the visible light emitting module for optical signal transmission. The truncated phased array receiving module is used to receive the modulated optical signal. The truncated phased array receiving module has multiple receiving surfaces, and each receiving surface contains multiple optical detection units. A multi-level differential noise reduction module is electrically connected to the prism phased array receiving module. The multi-level differential noise reduction module is used to perform multi-level differential noise reduction processing on the electrical signals output by multiple photodetectors on each receiving surface to generate the light intensity response value of each receiving surface. The multi-level differential noise reduction processing includes performing first-level differential processing between multiple photodetectors on the receiving surface to suppress local noise, and performing second-level differential processing between multiple receiving surfaces to suppress reflected light interference. The distance calculation module is connected to the multi-level differential noise reduction module. The distance calculation module is used to calculate the distance between the prism phased array receiving module and each visible light emitter based on the light intensity response value through filtering and distance calculation model. The positioning output module is connected to the distance calculation module. The positioning output module is used to determine the position coordinates of the prism phased array receiving module based on the distance using a polygonal positioning algorithm.

9. The system according to claim 8, characterized in that, The visible light emitting module includes: An orthogonal frequency division multiplexing unit is used to map digital signals onto multiple subcarriers to generate modulated signals; A DC bias drive unit is electrically connected to the orthogonal frequency division multiplexing unit. The DC bias drive unit is used to superimpose a DC bias current on the modulation signal to drive the visible light transmitter to output a modulated light signal containing positioning information.

10. The system according to claim 8, characterized in that, The frustum phased array receiving module includes: The pentahedral receiving architecture has five receiving surfaces with normal vector directions of (±1,0,0), (0,±1,0), and (0,0,1), respectively. An array-type light detection unit group is integrated into each receiving surface of the pentahedral receiving architecture. The array-type light detection unit group consists of a 9×9 array of light detection units, and the photosensitive area of ​​a single light detection unit is 5mm×5mm.

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