Structuring free space as prime rectangular areas (PRAs) with on-line path planning and navigation for mobile robots

A method is presented for modeling a robot environment and structuring its free space in terms of a set of overlapped prime rectangular areas (PRAs) which are suited for path planning and navigation tasks. Next, a connectivity table for the overlapped PRAs is constructed to provide the structure necessary for path-finding. Using the generated overlapped PRAs, a simple and computationally effective online path planning algorithm is proposed to generate the optimal collision-free path in terms of intersected PRAs from the PRA containing a start point to a PRA containing a goal point within the robot's environment. Since the movements between the PRAs cannot have fixed cost distance attached to them, an efficient technique that dynamically allocates cost to path segments as the path develops is proposed. A real-time execution algorithm is developed to control the robot during the execution of the planned path. Experimental examples based on the proposed algorithms with its results are presented for selected environments executed on the mobile robot Yamabico.M (Level-12).