Nice job by IEEE's Spectrum's Paul Wallich in creating a DIY "follow me" box (working with ArduCopter) to keep an eye on his kid on the way to school. Sample from the article, which appears in print this month:
On school-day mornings, I walk my grade-school-age son 400 meters down the hill to the bus stop. Last winter, I fantasized about sitting at my computer while a camera-equipped drone followed him overhead.
So this year, I set out to build one. For the basic airframe, I selected a quadcopter design for its maneuverability and ability to hover. Construction was straightforward: You can buy a quadcopter kit with all the pieces or, as I did, get parts separately and spend more time on system integration.
On the mechanical side, there’s a central frame to hold the electronics, spars of aluminum to support the motors and propellers, and legs to cushion the quadcopter’s landing (I made a few extra sets of legs out of foam board for easy replacement).
On the electronics side, there’s a main control board plus sensors, batteries, a power distribution board, power controllers for the motors (which draw tens of amperes, not what you’d manipulate with ordinary microcircuitry) and a radio receiver for standard remote-control flying, plus an RF modem for computerized control—I got both control systems for redundancy.
For the main control board, I chose an ArduPilot Mega, mostly because it integrates everything I needed—the CPU, input/output ports, a three-axis gyroscope and accelerometer, and a barometric altitude sensor. A daughterboard soldered on top holds a thumbnail-size GPS unit, a magnetometer (compass), and a slot for microSD card storage. The whole board is powered by a 5-volt feed from one of the motor controllers. (When programming it on the ground, you can power the board via a USB connection.)