In vehicles such as cars, minivans and SUVs, it's difficult to get a sense of what's behind you when you're backing up
. This can be a dangerous problem if there are small children around, such as when you're picking up your child after school or sports practice. Rear parking sensors (sometimes called Rear Park Assist) ensure that you're made aware of objects behind you when the vehicle is in reverse.
This type of parking aid system contain Echo-Location sonar used by the US Navy and is designed to detect objects near the vehicles' rear bumpers and warn drivers of their proximity during parking maneuvers. This system is designed with a voice distance indicator that literally tells the driver the vehicle distance in feet/inches to an obstacle. The sensors used in this system operate in all kinds of conditions (i.e. Fog, Rain, Snow, Darkness, Bright Sun). The system starts counting at 8 or 12 feet (depending on the model) and count down to 12 inches and are accurate to within +/- 2 inches.