ive seen the future http://www.ebay.co.uk/itm/ONE-CONCEPT-CLEANHERO-ROBOT-WINDOW-TABLE-CLEANER-QUIET-ROBOTIC-GLASS-CLEANING-/231148715404?pt=UK_HomeGarden_CLV_Cleaning_CA&hash=item35d1897d8c
".....built-in anti-crash algorithm as well as the sensor controlled obstacle detection."