IMU/Vision/Lidar integrated navigation system in GNSS denied environments

This paper aims to develop IMU/Vision/Lidar integrated navigation system which can provide accurate relative navigation information in GNSS denied environments. The developed integrated navigation system consists of an IMU, a vision sensor and a Lidar sensor. In order to overcome limitation of low accuracy of MEMS inertial navigation solution when GNSS signal cannot be used, 2-dimensional optical flow vector from vision sensor and Lidar range information between the system and ground surface are used. Two aided sensor data are complementarily employed in the system integration. Basically, by using the optical flow vector and relative height between vision sensor and ground surface, accuracy of the horizontal position estimates is improved. At the same time, by using compensated Lidar measurement, accurate vertical position can be estimated. The overall integrated navigation filter is constructed based on Extended Kalman Filter approach. Feasibility of the navigation filter is proven via simulation results. Finally, with real hardware system, an outdoor test is carried out for analyzing performance of the proposed integrated navigation system.