Sweeping. In olden times, people would sweep for hours and the floor would still be dirty. Then came the realization that they were trying to sweep dirt floors. Soon came wooden floors, carpets and, eventually, technology progressed to the point that mankind sent automated rovers to the planet Mars -where the dirt is called regolith. From this Mars rover technology sprung the Roomba - a fully autonomous sweeping device which, while convenient to the modern homemaker, is a nightmare to get into the ballpark and swing as a prop at baseball games. http://thesweethome.com/wp-content/uploads/sites/3/2016/02/01-robot-vacuum-irobot-roomba-650-630.jpg