Research On Visible Light Positioning Technology Under Indoor Illumination By Multiple Light Sources

As a mature positioning and navigation technology,GPS(Global Positioning Sys-tem)has been widely used in outdoor environments.However,due to the wireless signal attenuation and multi-path effect,it can not provide a reliable location service in indoor environments where the most frequent activities of the humans exist.In the past ten years,the indoor positioning technology based on radio waves has been widely studied,but has never been widely used because of device dependency,susceptibility to elec-tromagnetic interference and limited positioning accuracy.But the indoor positioning and navigation technology based on visible light communication(VLC)has become the research focus for its advantages of high security,immunity to electromagnetic inter-ference,high positioning accuracy and seamless integration of lighting and positioning.This paper studies the visible light positioning technology under indoor multi-light illumination.It primarily concerns about some of the key technical problems which still exist in the indoor multi-light positioning system.There are two major aspects to study,one is PD(Photo-diode)based multi-light positioning algorithm,and the other is the LED flickering problem of the image sensor based positioning system.Firstly,the indoor visible light positioning system is introduced.The basic prin-ciple of the indoor positioning system,the characteristics of common optoelectronic devices,the transmission channel model of an LED,and the basic principle of the com-mon positioning methods are introduced respectively.They lay a theoretical foundation for the study of the visible light positioning technology.Then,a new RSS(Received Signal Strength)-based positioning algorithm is pro-posed to tackle the issues of the existing PD-based visible light positioning algorithms,such as poor robustness and environment adaptability.The design of the new position-ing algorithm involves the development of the positioning signal model,the analysis of the received signal characteristics,and the performance evaluation and extension of the algorithm.The superiority of our proposed positioning algorithm is demonstrated by simulation analysis and experimental test.Finally,the LED flickering mechanism is analyzed pertaining to the LED flick-ering in the image sensor positioning system.Accordingly,the method of combining small modulation depth and optical neutral density filter(ONDF)as an auxiliary device is proposed to solve the LED flickering problem.The advantages and disadvantages of the existing anti-flickering methods are summarized.A flickering free positioning test platform based on the image sensor is developed and the basic performance metrics of the positioning system are tested.The results show that the proposed method can effec-tively solve the problem of LED flickering while ensuring the positioning performance.