Fast exploration using multirotors: Analysis, planning, and experimentation

Abstract

This work presents a system and approach for rapid exploration of unknown environments using aerial robots. High-speed flight with multirotor air vehicles is challenging due to limited sensing range, use of on-board computation, and
constrained dynamics. For robots operating in unknown environments, the control
system must guarantee collision-free operation, and for exploration tasks, the system should also select sensing actions to maximize information gain with respect to environment. To this end, we present a motion primitive-based, receding-horizon planning approach that maximizes information gain, accounts for platform dynamics, and ensures safe operation. Analysis of motions parallel and perpendicular to frontiers given constraints on sensing and dynamics leads to bounds on safe velocities for exploration. This analysis and the bounds obtained, inform the design of the motion primitive approach. Simulation experiments in a complex 3D environment demonstrate the utility of the motion primitive actions for rapid exploration and provide a comparison to a reduced motion primitive library that is appropriate for online planning. Experimental results on a hexarotor robot with the reduced library demonstrate rapid exploration at speeds above 2.25 m/s under a varying clutter in an outdoor environment which is comparable to and exceeding the existing state-of-the-art results.