You could press any button on your key fob, press any door handle, or step in front of the car so it detects an obstacle.
Assuming the driver did summon the car he must not have been paying much attention.
Either that or he "butt" summoned it.
Um, if it detects an obstacle, how did it hit the trailer?
It doesn't guarantee to detect every obstacle every time.
> It doesn't guarantee to detect every obstacle every time.
In Silicon Valley, they call this "eventually safe".
Which is probably how it ended up rolling over your child in the (hypothetical) first place.
It has ultrasonic sensors in the bumpers. They're too far down to detect a trailer at windshield level, but they'll detect the legs of a person standing in front of it.