Abstract: A pool cleaner and method for its operation provides for the efficient and systematic cleaning of the bottom of a rectilinear pool or tank in a controlled geometric pattern of parallel paths transversed between a pair of opposing sidewalls by having the pool cleaner complete a 180° U-turn at each wall, and when an end wall is reached, to effect a 90° turn and commence a similar pattern of parallel paths between the pair of end walls. A microprocessor, or programmable electronic controller, responds to signal-generating sensors that are activated at the pool's sidewalls, and to a program that also repositions the cleaner should it become blocked by a corner or other obstacle.