Development of a LiDAR system for low visibility conditions

Over the past years a lot of effort is being focused on realizing the vision of fully autonomously driving vehicles. The achievement of this goal strongly depends on the development of sensors that allow the perception of the environment by scanning it with high speed, precision and resolution. The sensors employed in autonomous vehicles typically comprise cameras, Radar and LiDAR Systems. Especially LiDAR and Camera Sensors deliver the necessary high-resolution data, but both suffer from strongly degrading signals in low visibility conditions. To guarantee the safe operation of autonomously driving vehicles the existing sensors need to be improved with respect to these conditions and new sensors need to be developed. In this contribution we present a LiDAR system design that is optimized for the operation in low visibility conditions. On one hand we address the technical details of the system such as choice of laser, detector, deflection unit and signal processing electronics. Besides the technical details of the system, we discuss the physical and technological limitations such as wavelength dependent scattering and absorption and eye safety considerations. We further give an outlook on a sensor fusion approach with a time-gated sensor with high lateral resolution for a better recognition of objects obscured by scattering media.