Planning Dynamically Feasible Trajectories for Quadrotors Using Safe Flight Corridors in 3-D Complex Environments

• Published in: IEEE robotics and automation letters Vol. 2; no. 3; pp. 1688 - 1695
• Main Authors: Liu, Sikang, Watterson, Michael, Mohta, Kartik, Sun, Ke, Bhattacharya, Subhrajit, Taylor, Camillo J., Kumar, Vijay
• Format: Journal Article
• Language: English
• Published: IEEE 01.07.2017
• Subjects: Aerial robotics; autonomous vehicle navigation; Collision avoidance; Ellipsoids; motion and path planning; Navigation; Planning; Real-time systems; Robots; Trajectory
• ISSN: 2377-3766; 2377-3766
• DOI: 10.1109/LRA.2017.2663526

There is extensive literature on using convex optimization to derive piece-wise polynomial trajectories for controlling differential flat systems with applications to three-dimensional flight for Micro Aerial Vehicles. In this work, we propose a method to formulate trajectory generation as a quadratic program (QP) using the concept of a Safe Flight Corridor (SFC). The SFC is a collection of convex overlapping polyhedra that models free space and provides a connected path from the robot to the goal position. We derive an efficient convex decomposition method that builds the SFC from a piece-wise linear skeleton obtained using a fast graph search technique. The SFC provides a set of linear inequality constraints in the QP allowing real-time motion planning. Because the range and field of view of the robot's sensors are limited, we develop a framework of Receding Horizon Planning , which plans trajectories within a finite footprint in the local map, continuously updating the trajectory through a re-planning process. The re-planning process takes between 50 to 300 ms for a large and cluttered map. We show the feasibility of our approach, its completeness and performance, with applications to high-speed flight in both simulated and physical experiments using quadrotors.