As technology becomes cheaper over time, so do interesting robotic-style toys and devices from electronics stores. Often you can see a robotic arm, bug, car, tank and so on for less than forty dollars. David found one for himself, and modified it with a larger battery, small Arduino-compatible board and an ultrasonic sensor for obstacle avoidance. Here it is in action:
The key to these modifications is to find something that has simple, direct controls to the motors or a recognisable motor control IC. Then using some simple circuitry you can interface with the Arduino digital outputs and create your own little monsters. An ideal board for these modifications is our Freetronics LeoStick - one of the smallest Arduino-compatibles on the market, with onboard USB, piezo and RGB LED:
For his explanation, code and examples - visit David's page here.