A robotic pool cleaner is intended to collect debris and sediment from swimming pools. Most models use a random motion pattern.
The pump is drawing the water from the bottom of the robot where the intake valves are located, through the filter and out to the top outlet of the cleaner. Debris and dust that are on the pool surfaces are being vacuumed into the filter section, and particles that are large enough stay inside the robots filter unit until cycle is done and disposal is being removed.
The drive motor gives robot a directional movement but it does not determine the route. The processor is made to determine the cycle time of the motors to a specific direction.
The more expensive models have advanced processors which remember and use the pool's size and shape to calculate the most efficient route to clean the entire pool.