A quadcopter is a multicopter lifted and propelled by four rotors. The motors are mounted in the same plane, on the helicopter, forming a square. This allows this quadcopter to lift vertically without rotating on itself. There are several advantages to quadcopters over comparably-scaled helicopters. The fact that four motors are involved reduces the minimum size of the propellers on each motor. This means that in case the quadcopter hits anything the damage is significant less than if a similar sized helicopter crashed. The following figure shows how the motors are mounted. The rotation direction is critical to the correct functioning of a quadcopter.
All motors have to rotate at the same speed for a vertical lift; however, motor 1 and 3 have to rotate opposite to motors 2 and 4. This is necessary to compensate the angular acceleration generated by each motor. This way the total angular acceleration should be zero, maintaining the quadcopter stable. This report has all the content which is needed to build your own project.
Author:- Joao Diogo Lisboa de Menezes Falcao, Terry Young Hwa Kim, Thu-Thao Nguyen