HandBat is a handheld Ultrasonic Radar device that sends out pulses of UltraSound and listens for Echos, like a Bat. It is intended for use by vision-impaired people or navigation in the dark.
Handbat is housed in a low-cost ($3.97) Rayovac Floating Lantern case from Walmart.
It is made from 5 parts:
These parts are widely available on Ebay, Sparkfun.com, Adafruit.com, YourDuino.com etc.
A kit with the needed parts is available HERE:
The completed HandBat (above) contains the YourDuino/Arduino microcomputer and battery holder inside the lantern case, the UltraSonic Sensor mounted on the front lens, and the beeper on the outside of the case.
Here is a good Educational article we have written about Ultrasonics and EchoLocation: Understanding the Science Behind the Ultrasonic Distance Sensor (click this link)
In use, the HandBat is held by the user and pointed in front of them and around to find out how close objects are. The maximum range is 2 meters (about 6 feet). The user listens to the beeper which tells how close objects are with different tones and rates of beep.
Note: A Kit of parts to build the Handbat (Not including the $4 Walmart Lantern!) is available HERE.