Modeling and Multivariable Control Techniques for Small Coaxial Helicopters

ight of small coaxial helicopters ( < 70cm rotor diameter) poses signicant challenges in terms of comprehensive yet computationally feasible modeling and control. The coaxial platform provides several advantages at small scales in terms of size, footprint, eciency and stability. This study compares techniques used for the modeling and control of such an aircraft in order to identify a viable control design for an experimental platform. Models of the various thrust, servo and motor dynamics are presented, and the delity of the model is assessed. In terms of control techniques, linear methods such as PID, LQR and H1 mixed synthesis are presented. PID control is generally found to be ineective in most cases including trajectory tracking and disturbance rejection. LQR and H1 control techniques outperform PID in this regard and provide respectable results. Furthermore, the H1 control scheme is especially eective in achieving tighter trajectories.