A Quad-copter (from Quad (four) and Copter (helicopter) is an aerial robot
combining a simple propeller mechanism with powerful electronics for limitless real ‐world applications. It is an embedded system comprising of micro controllers, sensors, flight gear and other integrated components. Multi-copter is a rotor-craft
with more than two rotors. An advantage of multi-rotor aircraft is the simpler rotor
mechanics required for flight control. Unlike single and double rotor helicopters
which use complex variable pitch rotors whose pitch varies as the blade rotates for
flight stability and control, multi rotors often use fixed‐pitch blades ; control of
vehicle motion is achieved by varying the relative speed of each rotor to change the
thrust and torque produced by each.