The Sunu band is a smart watch that is specifically designed to help the blind navigate around people and objects. It sends out ultrasonic waves up to 13FT away, and then provides haptic feedback to make blind people aware of objects and people. The range and feedback are fully customizable by way of an app. The Sunu Band can be paired to your phone by Bluetooth. It also detects openings such as doorways and threshold’s, but it doesn’t seem to be able to detect drop offs.
You can purchase the Sunu Band here for $299.