Guaranteed avoidance of unpredictable, dynamically constrained obstacles using velocity obstacle sets
Albert Wu · 2011
Dynamic obstacle avoidance is an important, ubiquitous, and often challenging problem for autonomous mobile robots. This thesis presents a new method to guarantee collision avoidance with respect to moving obstacles that have constrained dynamics but move unpredictably. Velocity Obstacles have been widely used to plan trajectories that avoid collisions with obstacles under the assumption that the path of the objects are either known or can be accurately predicted ahead of time. However, for real systems, this predicted path will typically only be accurate over short time-horizons. To achieve safety over longer time periods, the method introduced here instead considers the set of all reachable points by an obstacle assuming that the dynamics fit the unicycle model, which has known constant forward speed and a maximum turn rate (sometimes called the Dubins car model). This thesis extends the Velocity Obstacle formulation by using reachability sets in place of a single “known ” trajectory to find matching constraints in velocity space,