Lidar Research For Active Collision Avoidance Of Automobiles

With the increase of automobiles in China,traffic safety has become one of the main problems threatening life and property.It is important to study the active collision avoidance technology for reducing traffic accidents.Lidar on vehicle is the core sensor to provide judgment for active collision avoidance.Its ranging accuracy affects the radar performance.In this paper,the pulse ranging system is designed to realize active collision avoidance.The main factors affecting the ranging accurac are analyzed.A high precision vehicle lidar system including laser emission,temperature control,laser receiving,time identification,timing and control module is designed and implemented.A narrow pulse laser transmitting circuit with high repetition frequency is designed to concentrate the emission energy.A photodetector is used to receive the laser echo signal returned from the obstacle surface and a low noise and high gain amplifier circuit is designed.The temperature control circuit is designed to make the system work at the optimum temperature and improve its stability.According to the attenuation and broadening characteristics of the echo signal,the time-domain distribution model of the echo pulse is established.On this basis,a new dual-channel time discrimination circuit is designed to improve the identification accuracy.TDC-GP2 is used to measure the laser flight time interval.The measured time is converted into obstacle distance by FPGA,which is transmitted to the followup mechanism to provide judgment basis for active collision avoidance.Aiming at the problems of large volume,high power consumption and single scanning mode of traditional mechanical scanning components,an electronically programmed scanning mode based on liquid crystal phased array is proposed.On this basis,an algorithm for twodimensional scanning of road environment is developed.The high-resolution solid-state scanning without mechanical inertia and random direction is realized.Finally,an experimental platform is built.The experimental results show that the designed vehicle lidar can measure the distance of road environment with high precision.The maximum range of the system is 120 m,and the dynamic ranging error is less than 0.1m.It meets the requirements of active collision avoidance and promotes the development of intelligent driving.