| The indoor positioning technology is rapidly developed at present.Traditional indoor positioning technologies such as Bluetooth indoor positioning technology,radio frequency identification positioning technology,and ultra-wideband positioning technology show many disadvantages,such as low positioning accuracy,difficult device deployment,and disturbances liable to environment.Therefore,there is an urgent need for an indoor positioning technology with no limit from the environment and high positioning accuracy.Because of no electromagnetic radiation and high popularity rate,LED shows broad development prospects in indoor positioning.In this paper,the basic principles of visible light communication is fully studied and the positioning algorithms commonly used in current indoor positioning technology are compared.The deeply studied has been carried out on channel modeling,light source layout,positioning principle and hardware platform design in current visible light indoor positioning.The main contents and research results are as follows:Firstly,the mathematical modeling of the visible light communication channel is established.The physical characteristics of the white LED and the attenuation model of the channel are analyzed.The light source layout mode that meets the international lighting requirements is designed and the optical power,signal to noise ratio and bit error rate of the system are analyzed in this layout mode,Which provides a theoretical basis for the construction of hardware systems in later chapters.Secondly,the common positioning algorithm is given,including TOA algorithm,TDOA algorithm,RSSI algorithm,AOA algorithm and Fusion algorithm for multiple positioning algorithms.Finally,based on the analysis of the common positioning algorithms,a multi-point calibration linear approximation indoor positioning algorithm based on LED array is designed according to the visible light intensity attenuation model and its approximate linear distribution in small range and the algorithm is verified by theory.The simulation results show that in the model space of 0.8m×0.8m×0.8m,theoretical positioning error is within 10cm,which fully proves the theoretical feasibility of the algorithm.Thirdly,on the basis of theoretical analysis and experimental simulation,the designed algorithm is verified by experiments.The embedded hardware platform of indoor visible light positioning system based on STM32 is designed.The system experiment was carried out in the space model of 0.8m×0.8m×0.8m,which built by five wooden materials.The experimental results show that the positioning error is between 10cm and 20cm.Finally,base on the visible light indoor positioning technology and the GSM communication technology,4G transmission was utilized to accomplish the remote detection of indoor positioning results on the mobile terminal,which verified the practicality of the designed hardware platform. |
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