A Boston Dynamics SpotMini robot walks through a conference room during a robotics summit in Boston. It’s never been clear whether robotics company Boston Dynamics is making killing machines, household helpers, or something else entirely. But the secretive firm, which for nine years has unnerved viewers with YouTube videos of robots that jump, gallop or prowl like animal predators, is starting to emerge from a quarter-century of stealth. Photo: Charles Krupa/AP