Along with the new, free-roaming robots come new safety concerns. People worry about what happens if a robot spins out of control, or the first time a driverless car kills someone.

“It’s the fear of robots,” said Bryant Walker Smith, a fellow at the Center for Internet and Society at Stanford Law School who studies driverless cars. “There’s something scarier about a machine malfunctioning and taking away control from somebody.”

As a result, these robots require extra protective measures. The Google car has a padded front to soften any blow if the robot or a human causes an accident. The windshield is plastic, and the front of the car is rounded so it is less likely to hurt or trap pedestrians or cyclists.