Building on the Arduino experience from the high altitude balloon project (and inspired by the projects of Lucky Larry), I constructed a sonar system lovingly named ‘Sonia the Sonar’, a sonar system developed to detect motion within a 180 degree view and report back to the user on movement in the area. Sonia had three major components: an HC-SR04 ultrasonic transducer for the distance ranging, a Futaba S3003 servo for rotation of the transducer and an Arduino Uno R3 to read the transducer outputs, control the servo and output the angle and range of objects within the field of view to a laptop.
For reading the sensor outputs directly from the microcontroller, a microtivity LCD module that output ultrasonic transducer range observation and the servo position output was mounted to the project enclosure.
For a more graphic visualization of the range and position of any object that came into the sonar field of view, code written in Processing and running on a laptop parsed the range and position data from the microcontroller and displayed it on series of concentric range rings. As I was really interested in capturing people or things moving within the sonar range, the visualization was modified to show movement rather than the static background.
I think that a fun future extension to this project would be to have Sonia track the detected moving object (for my situation likely a person in my office) and then try to identify the person based on their distinctive walking cadence and direction of motion (i.e. can the person be identified by them walking towards the general direction of their desk by their average speed of movement).