Theoretical And Experimental Research On Detection Of Bumps And Obstacles On Road Surface By Vehicle-mounted Lidar

Lidar can accurately obtain three-dimensional information of the road environment,so it is one of the essential sensors for developing unmanned vehicles and has broad application prospects in the field of unmanned driving.To this end,the paper studies the detection of bumps and obstacles on the road by laser radar,and aims to provide a theoretical basis for accurately identifying the small bumps on the road surface.Through in-depth data investigation,the paper gives the laser radar ranging principle,the laser radar echo calculation shock response function and the mathematical model of laser echo calculation.The paper deduces the analytical solution of the impulse response function under the conditions of plane,spherical and cone targets and calculates and analyzes the influence of different target shapes and beam incident angle on the laser echo waveform.Under the assumption of square obstacles,the paper deduces the analytical solution of the echo response function of laser radar to the detection of bumps on pavement,calculates the echo waveform of lidar when detecting different obstacles and obtains the evolution law of echo waveform when passing through obstacles from far to near axial direction,which means that the presence of embossed obstacles can cause distortion of the impulse response function of the road surface,providing a theoretical basis for the detection of concave obstacles by lidar waveform analysis.On this basis,the paper introduces a laser radar ranging statistical model and simulates a one-dimensional distance image obtained by laser radar scanning and detecting concave and convex obstacles with length,width and height of 0.1m,0.5m and 0.1m on the road surface.The paper gives the evolution law of the one-dimensional distance image when the obstacle passes from the far to the near edge,and the one-dimensional contour of the obstacle can be clearly seen.The paper established an experimental system for on-board lidar echo waveform analysis,studies the influence of different incident angles on the echo waveform of the road surface and the laser echo waveform when detecting the obstacles on the road surface,compares the difference in ranging results when there is no obstacle and finally verifies the correctness of the theoretical results.The research results of the thesis have certain reference value for the research of laser radar in detecting the slight bumps on the road surface under the vehicle condition.