A quadrotor is a helicopter with four rotors placed at equal distance from the crafts centre of gravity, controlled by letting the different rotors generate different amount of thrust. It uses various sensors to stay stable in the air, correct readings from these sensors are therefore critical.
The purpose of this project is to analyse the feasibility of a quadrotor camera surveillance system by optimizing the handling of vibrations, video signal and external disturbances for a quadrotor and by reducing vibrations, electromagnetic interference and external disturbances the quadrotor’s stability can increase.
The quadrotor will be flown through first person view and should be able to hover at 10 meters altitude in a radius of 3 meters. Only sensor readings will be optimized, not data processing. The flight controller used will be a MultiWii Pro which has an accelerometer, a gyroscope, a magnetometer, a GPS and a barometer.
Balancing motors and applying vibration dampening material between the motors and the frame vibrations were reduced by 73 %. Electromagnetic interference to the magnetometer was made negligible when the magnetometer had a distance of 3 cm from the power circuit. Video signal was improved by applying a LC-filter. Isolating the barometer improved calculations for the altitude. The quadrotor’s position could be locked within a radius of 4 meters and its altitude could be locked in an interval of 2 meters. The quadrotor cannot be considered stable enough for automatic camera surveillance, however with software improvement it could be.
Source: KTH
Authors: Hjelm, Emil | Yousif, Robert