Fast Trajectory Planning for Multiple Quadrotors using Relative Safe Flight Corridor This paper presents a new trajectory planning method for multiple quadrotors in obstacledense environments. We suggest a relative safe flight corridor (RSFC) to model safe region between a pair of agents, and it is used to generate linear constraints for intercollision avoidance by utilizing the convex hull property of relative Bernstein polynomial. Our approach employs a graphbased multiagent pathfinding algorithm to generate an initial trajectory, which is used to construct a safe flight corridor (SFC) and RSFC. We express the trajectory as a piecewise Bernstein polynomial and formulate the trajectory planning problem into one quadratic programming problem using linear constraints from SFC and RSFC. The proposed method can compute collisionfree trajectory for 16 agents within a second and for 64 agents less than a minute, and it is validated both through simulation and indoor flight test.

Realtime Trajectory Generation for Quadrotors using Bspline based Nonuniform Kinodynamic Search In this paper, we propose a timeefficient approach to generate safe, smooth and dynamically feasible trajectories for quadrotors in the obstaclecluttered environment. By using the uniform Bspline to represent trajectories, we transform the trajectory planning to a graphsearch problem of Bspline control points in discretized space. Highly strict convex hull property of Bspline is derived to guarantee the dynamical feasibility of the entire trajectory. A novel nonuniform kinodynamic search strategy is adopted, and the step length is dynamically adjusted during the search process according to the Euclidean signed distance field (ESDF), making the trajectory achieve reasonable timeallocation and be away from obstacles. Nonstatic initial and goal states are allowed, therefore it can be used for online local replanning as well as global planning. Extensive simulation and hardware experiments show that our method achieves higher performance compared with the stateoftheart method.