Open-sector rapid-reactive collision avoidance: Application in aerial robot navigation through outdoor unstructured environments.

A new reactive collision avoidance method for navigation of aerial robots (such as unmanned aerial vehicles (UAVs)) in unstructured urban/suburban environments is presented. Small form-factor aerial robots, such as quadcopters, often have limited payload capacity, flight time, processing power, and sensing capabilities. To enhance the capabilities of such vehicles without increasing weight or computing power, a reactive collision avoidance method based on open sectors is described. The method utilizes information from a two-dimensional laser scan of the environment and a short-term memory of past actions and can rapidly circumvent obstacles in outdoor urban/suburban environments. With no map required, the method enables the robot to react quickly and navigate even when the enivornment changes. Furthermore, the low computational requirement of the method allows the robot to quickly react to unknown obstacles that may be poorly represented in the scan, such as trees with branches and leaves. The method is validated in simulation results and through physical experiments on a prototype quadcopter system, where results show the robot flying smoothly around obstacles at a relatively high speed (3 m/s).