| With the help of a series of unmanned ground vehicle (UGV) competitions, the development of the technology in UGV has grown rapidly in recent years, which also makes the practical application of UGV be a reality. In this field, 3D environment modeling and mapping are essential tasks for UGV in unstructured outdoor scenes. In order to complete reliable UGV's motion planning autonomously, an effective approach for 3D environment modeling is prerequisite to perform online 3D mapping, which can represent the real outdoor environment accurately.To guarantee reliable real-time motion planning for UGV, a local map building algorithm has to be presented by using the result of 3D environment modeling. In our work, a data structure of queue is updated in real-time to complete local elevation map building on the basis of the classic elevation map. Moreover, the results of obstacles clustering and direction angle generating are used to guide UGV's autonomous motion planning. In order to overcome the phenomenon of "the trails of moving objects" caused by limited 2D laser scanning data, the results of the dynamic targets'online tracking are integrated into local map building, which can eliminate the trails in real-time and generate the local map in a more accurate and practical way.To meet the demand of dealing with complex computation caused by large scale environment, a fast voxelization algorithm is proposed for 3D environment modeling and mapping. This algorithm can automatically search partition strategy which divides the 3D range data into unified blocks represent as voxels. Since the 26-neighourhood and parent-child-relationship models are constructed in the proposed voxelization algorithm, it makes large-scale environment digitalization much easier to be accomplished in a more efficient way.To test the proposed approaches'validity and practicability, a number of experiments are conducted in our campus on the UGV platform developed by our laboratory. The experiment results and corresponding data analysis show that our real-time elevation map is effective for guiding UGV motion planning. Furthermore, the result of large-scale 3D scene mapping based on multiple 2D laser scanners can accomplish DUT campus digitalization effectively. |
