This plastic owl on a robot base runs around the courtyard (randomly) for about 40 seconds, changing direction when it strikes an obstacle. Then it rests for about 10 minutes and runs again. The goal is to discourage squirrels from coming in and digging--we'll see.
Major parts required include:
Arduino Motor Shield
(8) AA batteries (rechargeable)
Robot motor base
I printed an "owl holder" and an "arduino holder" using a 3d printer. These could be fabricated from wood if necessary.
I added wires to the motors. The left motors are tied together in parallel and the right motors are tied together in parallel, then each set (left set and right set) are attached to the motor control outputs on the motor shield. The power supply (8 AA batteries) is run through a SPST toggle switch (on-off switch) to the Vin and Gnd on the motor shield.
The Arduino sketch (owl.ino) is loaded into the Arduino
The owl (it only weighs a few ounces) is attached to the top of the robot base.
Turn on the power and let it go. When the robot owl strikes an obstacle, the motors can't turn and they draw more current. The motor shield allows this current to be measured and the software sketch "senses" the increased current and causes the the robot owl to back up and turn.