CN-121978624-A - Calibration-free wireless light positioning method and system

CN121978624ACN 121978624 ACN121978624 ACN 121978624ACN-121978624-A

Abstract

The invention discloses a calibration-free wireless light positioning method and a calibration-free wireless light positioning system, and relates to the technical field of indoor positioning. According to the method, a receiving end photoelectric detector is used for acquiring light signals of a plurality of LED light sources with known coordinates, the intensity of the received signals is measured, after sequencing and coordinate matching, an intensity and distance association formula is deduced based on a lambertian transmission model and a geometric position relation, an unknown constant is eliminated by using an intensity ratio, a nonlinear equation set related to the position coordinates of the receiving end is constructed by combining known or unknown conditions of lambertian orders, and a two-dimensional position coordinate is obtained by solving. According to the invention, the lambertian model parameters and the m value do not need to be calibrated in advance, the deployment maintenance cost is reduced, the 'just-in-time use' is realized, the stability of positioning precision and the environment self-adaptive capacity are improved, and an economic and efficient scheme is provided for practical and large-scale indoor wireless light positioning.

Inventors

YOU XIAODI
Nie Zepeng
WU DECHUN
SHEN GANGXIANG
GAO MINGYI
XU TIANYU

Assignees

苏州大学

Dates

Publication Date: 20260505
Application Date: 20260116

Claims (10)

1. A method for calibrating wireless light positioning, comprising: step S1, a receiving end obtains optical signals from a plurality of LED light sources with known coordinates through a photoelectric detector and measures received signal intensity values corresponding to the optical signals; S2, sorting the received signal intensity values according to the magnitude of the amplitude values, and identifying LED light source coordinates corresponding to the received signal intensity values based on a time division multiplexing mechanism; S3, deriving a correlation formula of the received signal strength and the LED light source-receiving end distance by combining a geometric position relation of an LED light source and a photoelectric detector based on a lambertian transmission model, and eliminating unknown constant parameters by utilizing a ratio relation of the received signal strength to construct a nonlinear equation set, wherein variables to be solved of the nonlinear equation set comprise receiving end position coordinates when the lambertian order m is known, and the variables to be solved of the nonlinear equation set comprise the receiving end position coordinates and the lambertian order m when the lambertian order m is unknown; And S4, carrying out numerical solution on the nonlinear equation set to obtain the two-dimensional position coordinates of the receiving end.
2. The calibration-free wireless light positioning method of claim 1, wherein the geometric positional relationship between the LED light source and the photodetector is as follows: wherein Is the linear distance between the LED light source and the receiving end, Is the exit angle of the LED light source, For the angle of incidence of the photodetector, The vertical distance between the plane of the LED light source and the plane of the photoelectric detector.
3. The calibration-free wireless light positioning method of claim 1, wherein the correlation formula between the received signal intensity and the LED light source-receiving end distance is as follows: wherein For receiving the signal intensity, C is a constant parameter in a lambertian transmission model after integrating the physical characteristics of the LED light source and the photoelectric detector, m is a lambertian order, Is the linear distance between the LED light source and the receiving end, The vertical distance between the plane of the LED light source and the plane of the photoelectric detector.
4. The method of calibrating-free wireless light positioning according to claim 1, wherein the system is configured to deploy at least three LED light sources with known coordinates when the lambertian order m is known, and to receive the position coordinates when the three LED light sources with known coordinates are actually deployed As the only variable to be solved A system of nonlinear equations of the form: , , Wherein, the 、、 For the first three received signal strength values after sequencing, and ; 、、 Respectively the received signal strength value 、、 The distance from the corresponding LED light source to the receiving end.
5. The method of calibrating-free wireless light positioning according to claim 4, wherein the system is configured to deploy at least four LED light sources with known coordinates when the lambertian order m is unknown, and to receive the end position coordinates if the four LED light sources with known coordinates are actually deployed And lambertian order m is a co-pending variable A system of nonlinear equations of the form: , , , Wherein, the 、、、 Is the ordered received signal strength value, and ; 、、、 Respectively the received signal strength value 、、、 The distance from the corresponding LED light source to the receiving end.
6. The calibration-free wireless light positioning method of claim 5, wherein the method for obtaining the two-dimensional position coordinates of the receiving end by performing numerical solution on the nonlinear equation set is as follows: S41, initializing iteration parameters, including: Setting initial estimated value of variable to be solved, when lambertian order m is known, the variable to be solved is only the position of receiving end Its initial estimated value is set as When the lambertian order m is unknown, the variable to be solved is Its initial estimated value is set as , An initial value of lambertian order; Initializing an iterative calculator Setting the maximum iteration number as Initial value of damping factor adjustment coefficient First convergence threshold Second convergence threshold Damping factor initialization coefficient ; Based on the current initial estimate Calculating an objective function vector Jacobian matrix Further calculate the hessian matrix approximation And gradient vector Wherein when the lambertian order m is known, the objective function vector When the lambertian order m is unknown, the objective function vector ; Initializing damping factor , Is a matrix Diagonal elements of (2); s42, setting the first convergence condition as a gradient vector Is satisfied by an infinite norm of (1) , Representing the gradient vector Judging whether the first convergence condition is satisfied or not: if yes, go to step S46; If not, further judging the current iteration times Whether or not to be smaller than ; If it is Step S46 is performed; If it is Step S43 is performed; S43. order Constructing a system of linear equations Solving the equation set to obtain a step length vector Wherein Is a unit matrix; S44, calculating the step size vector Step size norm of (a) Setting the second convergence condition as Judging whether a second convergence condition is satisfied: if yes, go to step S46; If not, based on the current estimated value Step size vector Calculating candidate estimated values : According to the candidate estimated value And the current estimated value Calculating the ratio of the actual descent quantity to the model predictive descent quantity : Wherein Is a quadratic model function at the current position estimation point, and has the expression of ; S45 according to The value judges whether to accept the update and adjusts the parameters: If it is Indicating that the iteration is effective, accepting the candidate position update, and making Recalculating the objective function vector Jacobian matrix Hessian matrix approximation And gradient vector Adjusting damping factor Returning to the execution step S42 to carry out convergence judgment again; If it is Indicating that iteration is invalid, rejecting candidate position update, and maintaining the current position estimated value Invariable, adjust damping factor And update the damping factor adjustment coefficient Returning to the execution step S42 to carry out convergence judgment again; s46, outputting the current estimated value The position coordinate part in the (b) is the final horizontal coordinate positioning result of the receiving end.
7. The calibration-free wireless light positioning method of claim 6, wherein when the lambertian order m is unknown, the iterative updating method of the lambertian order m is as follows: s401 setting a search range of lambertian order m Search step Correction coefficient ; S402, in the search range In, with the search step length Traversing the candidate order values, and executing the following steps for each candidate order value: selecting two groups of different LED light source combinations, constructing a corresponding nonlinear equation group based on the current candidate order, respectively solving by adopting a Levenberg-Marquardt algorithm to obtain two groups of position preliminary estimated values, and calculating Euclidean distance between the two groups of position preliminary estimated values; S403, selecting a candidate order value minimizing the Euclidean distance By the formula Obtaining the optimized lambertian order And takes the initial value as the initial value of the lambertian order in the next iterative calculation.
8. The calibration-free wireless light positioning method according to claim 1, wherein in the lambertian transmission model, a line-of-sight transmission channel gain expression of wireless light from an LED light source to a photoelectric detector is: , Wherein m is lambertian order, d is the linear distance between the LED light source and the photodetector, A is the physical area of the photodetector, For the emission angle of the LED light source, For the angle of incidence of the photodetector, For the field angle threshold of the photodetector, For the gain of the optical filter, Gain for the optical concentrator.
9. The calibration-free wireless light positioning method of claim 1, wherein all the LED light sources are fixedly installed on the same horizontal plane, the photoelectric detector is horizontally placed, and a fixed vertical height is kept between the photoelectric detector and the LED light sources.
10. A non-calibrated wireless optical positioning system, comprising the following modules: The system comprises an optical signal acquisition and intensity measurement module, a light source module and a light source module, wherein the optical signal acquisition and intensity measurement module is used for acquiring optical signals from a plurality of LED light sources with known coordinates and measuring received signal intensity values corresponding to the optical signals; The intensity sorting and light source coordinate matching module is used for sorting the intensity values of the received signals according to the magnitude of the amplitude values and identifying LED light source coordinates corresponding to the intensity values of the received signals based on a time division multiplexing mechanism; The system comprises an equation set construction module, a non-linear equation set, a light source module and a light source module, wherein the equation set construction module is used for deducing a correlation formula of the received signal intensity and the distance between the LED light source and the receiving end based on a lambertian transmission model by combining the geometric position relation of the LED light source and the photoelectric detector, and eliminating unknown constant parameters by utilizing the ratio relation of the received signal intensity; and the positioning result output module is used for carrying out numerical solution on the nonlinear equation set to obtain the two-dimensional position coordinate of the receiving end.

Description

Calibration-free wireless light positioning method and system Technical Field The invention relates to the technical field of indoor positioning, in particular to a calibration-free wireless light positioning method and system. Background With the popularization of intelligent terminal devices, demands for location-based services continue to increase, and indoor positioning technology has become a research hotspot of current interest. In complex indoor environments such as exhibition halls, warehouses, malls, underground parking lots and the like, accurate acquisition of position information of articles or workers is a key for realizing various scene applications. However, the development of indoor positioning technology faces many challenges. Although the outdoor positioning system can provide high positioning accuracy in an open environment, under an indoor scene, factors such as wall shielding, electronic equipment interference and the like can seriously influence the function exertion of the system, and the requirement of accurate positioning cannot be met. Meanwhile, the global positioning system is difficult to penetrate through the wall, and the importance of the positioning technology specially aiming at indoor environments is further highlighted. With the rapid spread of LED lighting technology, wireless light localization (wireless optical positioning, WOP) technology based on indoor Visible Light Communication (VLC) technology is gradually coming into the field of research. The technology can realize indoor positioning by utilizing the LED lamp for illumination, and becomes a candidate technology with great potential in the indoor positioning field by virtue of the advantages of high precision, low deployment cost, high safety, short response time and the like. Currently, indoor wireless optical positioning technologies mainly include various implementations based on images, received Signal Strength (RSS), time of arrival (TOA)/time difference of arrival (TDOA), angle of arrival (AOA)/angle difference of arrival (ADOA), and the like. The WOP system based on TOA/TDOA, AOA/ADOA and images needs additional auxiliary equipment to acquire time, angle or image information, has high requirements on experimental equipment, can acquire RSS values conveniently through a Photodiode (PD), has cost advantages, and is widely applied. However, the existing WOP system based on RSS trilateration has significant limitations in practical application, and before the system operates, data must be collected in a geometric measurement mode and tedious calibration operation is performed, so that time and labor costs are high. Specifically, the conventional trilateral positioning system based on RSS calibration needs to complete two parts of core calibration work before each positioning: the first part is to calibrate constant parameters in the lambertian model. Since LEDs generally have beam divergence characteristics, typically modeled as lambertian light sources, the calibration process requires measuring a reference power directly under at least one LED lamp and further calibrating the emitted power of the LEDs based on the reference power ) A priori information such as physical area (a) of the PD detector, optical concentrator gain (g), optical filter gain (T), lambertian order (m), etc. The calibration mode has obvious defects that the reference power measurement operation before positioning implementation not only increases the labor and time cost of system deployment, but also is easily influenced by factors such as environmental interference, equipment installation deviation, human operation difference and the like, and additional measurement errors are introduced. The second part is to calibrate the order m of the lambertian model. Under the condition that m is unknown, under the condition of fixed incidence angle and LED-PD interval, the function relation is fitted by changing the emission angle and collecting the corresponding received powerAnd further determining the value of m. It is common practice to control the angle of incidence to 90 ° and the LED-PD spacing d to be equal to the vertical height h, where only m is a variable, calibration is achieved by data fitting. However, the process relies on a large amount of experimental data acquisition, is complex in operation, consumes time and labor, and severely restricts the rapid deployment and practical process of the system. After the calibration of the two parts is completed, the system can acquire the received power of three LEDs through PD, calculate the distance between each LED and the receiving end, and finally calculate the actual position of the receiving end based on the trilateral positioning principle (such as the least square method). In addition to the problems of the calibration procedure itself, the prior art has the following drawbacks: Firstly, the system deployment cost is high, the reference power is measured manually in advance to cali