Simulation Of Laser Source For Self-localization And Navigation In Mountainous Areas Based On FDTD

The development of mountain agriculture is great significance to the agricultural and rural economy.Due to GPS positioning and navigation system are widely used in agricultural positioning applications,especially affected by tall obstacles and produce large errors around,so it’s not suitable for the application of unmanned machinery in mountainous areas.The Optic-lidar as one of the most important components of the optic-lidar is an important self-positioning system and effective solution for these problems.Therefore,the optimization of light source system was one of the key technologies to improve the accuracy and self-sustaining of the system.This work focused on the structure and parameter for design of the light source of optic-lidar.The optical system was designed and optimized by FDTD.The specific work was as follows:Firstly,we expounded the basic theory of FDTD and the interactive interface,used the establishment/operation of the interface,analyzed the results and the run the text program,established a brief physical model with the geometric structure in material properties,and give the definition of simulation area and simulation structure,respectively.Secondly,according to the collimation and beam expanding optical system of the light source,the parameters of the semiconductor laser source with the central wavelength of 905 nm are optimized.The typical value of the vertical light fieldθ_⊥with 25°and the parallel light fieldθ_//with 13°with the far-field light intensity with asymmetric elliptical distribution,respectively.Finally,based on the above conclusions,the simulation of 8-channels optical system is carried out,and the more optimized light source parameters are obtained:longitudinal distribution spacing of 19.326 mm,light source center spacing of 1.58 mm,respectively.In the same way,16-channels are arranged in radian,and 3D modeling of the system shows that the distance between the obstacle and the obstacle with 80 m in front of the left.The results show that FDTD not only saves experimental steps in the design of laser radar light source and optical path system,but also achieves simulation and verification effect,which provides strong support for the final development of lidar system.The simulation of FDTD for design system is realized,which makes it possible for optic-lidar to reduce the cost of research and development,and finally apply it to mountain farming environment.