Trajectory planning for narrow environments that require changes of driving directions

In the area of mobile robotics, trajectory planning is the task to find a sequence of primitive trajectories that connect two configurations, whereas non-holonomic constraints, obstacles and driving costs have to be considered. In this paper, we present an approach that is able to handle situations that require changes of driving directions. In such situations, optimal trajectory sequences contain costly turning maneuvers – sometimes not even on the direct path between start and target. These situations are difficult for most optimization approaches as the robot partly has to drive paths with higher cost values that seem to be disadvantageous. We discuss the problem in depth and provide a solution that is based on maneuvers, partial backdriving and free-place discovery. We applied the approach on top of our Viterbi-based trajectory planner.