Robots have been around a lot longer than you might suspect. In 350 BC, Greek mathematician Archytas built "the Pigeon," a mechanical bird that ran on steam. It was one of the earliest studies of flight. In 1495, Leonardo DaVinci created a mechanical device that resembled an armored knight. It contained mechanisms that allowed the "knight" to move like a real person. In 1898, Nikola Tesla built a remote-controlled robot boat and demonstrated it at Madison Square Garden in New York City. Robots have come a long way since Tesla's creation. In 2002, the ASIMO robot, created by Honda, rung the opening bell at the New York Stock Exchange.
The challenge here is to create a robot powered only by a light source. Batteries, rubber bands or any other energy sources are not allowed. The robot only drives forward; no micro-controller is used. The body is made from LEGOs and a solar panel is used to covert light to electricity, which is stored in a capacitor. A voltage trigger is used to determine when the capacitor is charged. When triggered, a transistor then floods the motor with energy from the capacitor. This is a simple, straightforward project and no elaborate designs are needed to be successful.
DTMF stands for "Dual tone multiple frequency." Here, the robot receives commands in the form of these tones and then performs the required actions. A dedicated modem is installed in the robot, which then receives the tones via a micro-controller. The modem decodes the DTMF tones and then performs predefined tasks, including moving back and forth or right to left. The micro-controller is interfaced with some DC motors so the robot can move in different directions. To complete the project, you'll need a power supply, a GSM modem/phone, a micro-controller-based control unit, DTMF drivers and the robot mechanical assembly.
This robot is designed to use ultrasonic sensors to sense obstacles in its path. It can then deviate from the path or shut down. The sensors use ultrasonic waves to determine if obstacles are in the way. An 8-bit micro-controller is employed to communicate with the sensors and acts based on the feedback it receives. DC motors are used to rotate the robot's wheels. To build this robot, a regulated power supply is needed along with a micro-controller control unit, ultrasonic sensors and geared DC motors.