Going back to station

I am new to arduino and i intend to make a robot that collects garbage from a beach. After certain time the robot has to go back to a station for garbage evacuation. The problem here is how could the robot know it's way to the station.
The dimensions of the area that will be cleaned is 30x20m.
Sorry for my bad english.

Use some kind of transmitter at the station that the robot can detect. Look at iRobots big hockey pucks cleaning floors and navigating back to its charging station. They probably use some kind of position calculation combined with IR.

How new are you to Arduino and mechanics ?

This is a very difficult task

  • how do you find rubbish?
  • how do you pick it ?
  • how do you drive on sand?