The Research And Implementation Of Quad-rotor Three-dimensional Real-time Positioning Based On CSS Technology

Based on the fact that the technology of Chirp Spread Spectrum has been widely applied to large-scale real time communication programs such as wireless real time location and Wireless Sensor Network, this thesis proposes to build two anchor nodes drawing on CSS technology, one on the ground, the other on the quad-rotor, and to calculate the accurate real time distance between the two anchor nodes, so as to locate the quad-rotor accurately and three-dimensionally. This is supposed to replace the use of GPS on the quad rotor for three-dimensional location.The author has accomplished the following work:(1) Analyzing the researches home and abroad on Wireless sensor network positioning; analyzing and describing the key technologies of three-dimensional location system based on CSS, which include Symmetrical Double-Sided Two Way Ranging, multilateral positioning technology, Trilateral positioning technology relied on Maximum Likelihood and so on.(2) Exploring the theory concerning the application of CSS to ranging and its implementation; doing experiments on MATLAB to testify. This work mainly analyzes and compares the factors that can cause offset frequency of the clock drawing on SDS-TWR, compares the errors of SDS-TWR and of the traditional method based on arrival time in measuring distances, simulates the environment which is equipped with300anchor nodes through multilateral positioning technology and Maximum Likelihood Estimation Method under in a three dimensional space, analyzes the location errors, network coverage rate and location accuracy, concludes that the above measuring and node location technology can greatly decrease the errors, designs the overall structure of this three-dimensional positioning system and implementation scheme, and testifies and analyzes them in details.(3) Researching the wireless sensor hardware based on CSS technology and the realization of the CSS Three-dimensional location system, testing the system in real environment and analyzing the results.The three-dimensional location system, analyzed and designed by this thesis, based on CSS technology, applies comprehensively SDS-TWR, multilateral positioning technology, and Maximum Likelihood Estimation. It can locate the anchor nodes three-dimensionally, collect the figures on x, y, z, and reduce the location errors to1-2cm, which perfectly satisfies the needs of small quad rotors, which quite probably will be used widely in the future, when collecting data, doing communication relay and automatically navigating, to get accurate three-dimensional lactation information with low cost and low power consumption.