PHILADELPHIA — A hitchhiking robot that captured the hearts of fans worldwide has met its demise in the U.S. The Canadian researchers who created hitchBOT as a social experiment told The Associated Press that someone in Philadelphia damaged the robot beyond repair early Saturday, ending its first American tour after about two weeks. “Sadly, sadly it’s come to an end,” said Frauke Zeller, one of the robot’s co-creators. The kid-size robot set out to travel cross-country after successfully hitchhiking across Canada in 26 days last year and parts of Europe.