Research Of Distributed Laser Position Location System Based On TDOF

The background of indoor positioning system is studied in this paper.A set of indoor positioning system based on time difference of flight(TDOF)is designed.The system contains laser semiconductor as signal source and distributed high-speed laser pulse receivers.The working principle and key technical problems of the scheme are analyzed.A laboratory prototype of system has been developed successfully.A large number of system results from the prototype show that the indoor laser positioning system has reached the expected standard,which has the advantages of high measurement accuracy and high spatial expansibility.Firstly,the domestic and overseas methods of indoor positioning systems are studied and summarized.Based on the analysis of the requirement of positioning function,a kind of high precision and high frequency indoor positioning method is proposed.Based on this method,the algorithms of Gauss Newton iteration method and least squares method used to solve the spatial coordinates of are introduced in detail.At the same time,a set of time-division multiplexing system is designed to solve the problem of multi-point measurement.A kind of high frequency stable semiconductor laser emission system is developed.The power characteristics and spectral characteristics of the semiconductor lasers are discussed.The working principle of the semiconductor laser driving circuit is studied in detail.A pulse laser receiving system was developed.The design idea of the pulsed laser system and the design of the receiving circuit are analyzed in detail.The laser light source is divided into synchronous light source and positioning light source.The high response photo detector APD is used to detect the pulse signal from the laser light source.The TDC-GP21 chip is used to calculate the TDOF signal based on the trigger signal.Finally,the TDOF signal is transmitted to the PC terminal through the serial port.The positioning algorithm is used to locate the TDOF signal.The core chip STM32F103 is used in all system to reduce the system design costs.A display software is designed and two smooth trajectory algorithms are used to reduce the external noise and the adverse effects of the system error.The two methods are simulated and the simulation data are analyzed and evaluated.Some points to be measured are selected in the experiment.First,the experimental environment requirements,calibration experiment are introduced.The experimental results show that the average positioning error of the system can be optimized within ±6mm,and the positioning accuracy can be further improved by reducing the measurement frequency.