An RC car with aluminum foil on the front. This guy uses capacitance to find out where things are, though it still needs some work.
Most of the work was done by a friend of mine, but I helped replace the arduino (the first was busted) and assisted my brother in the programming. It uses an L298N motor driver with some RC car, and runs off of five AA batteries. The Arduino is an Uno.
More details to come later as project progresses and changes, and as requested.
How the Capactive Displacement Sensor Works
Technically, the aluminum foil on the front of the robot is a Capacitive Displacement Sensor (not a very good one, but it is cheap). The arduino on board measures the capacitance by recording how long it takes for one pin connected to the aluminum to recieve a signal after the signal was sent by another pin connected to the aluminum with a resistor (for a more in-depth explanation, read here).
Using the capacitance data, the robot can determine when it is either near something conductive or if it has hit a wall (no distinction between the two is made). When the capacitance goes over a certain value, the robot backs up, turns right, and continues on.
This is a companion discussion topic for the original entry at https://community.robotshop.com/robots/show/rc-steering-with-capacitance