Patent ID: 7805220

Claim:
A method of operating a robot cleaner comprising: (a) generating an internal map of an area comprising a plurality of subgrids, each subgrid comprising a plurality of cells; (b) generating a subgrid map for each subgrid of the internal map, wherein the subgrid map has a higher resolution than resolution of the internal map; (c) causing the robot cleaner to travel on a surface along a travel path from one subgrid to another subgrid in a spiral; (d) during the traveling in each subgrid: (i) gathering data corresponding to each traveled cell and each non-traveled cell of the subgrid; (ii) at least partially cleaning the traveled cells of the subgrid; and (iii) storing status data for each cell in the subgrid map; (e) determining which part of the subgrid map has a highest density of uncleaned cells; (f) using the subgrid map to calculate a travel path to the part of the subgrid that has a highest density of uncleaned cells; (g) using the subgrid map to determine if the travel path is free from obstructions; and (h) if path is obstructed, rotating the travel path by a predetermined number of degrees and repeating steps (f)-(g); and (i) if path is not obstructed, repeating steps (c)-(h).