Modeling and Control of Coaxial UAV with Swashplate Controlled Lower Propeller

Abstract

There is a growing interest in the design and control of coaxial vehicles for the purposes of autonomous flight. These vehicles utilize two, contra-rotating propellers for generating thrust and swashplates for generating pitch and roll. In this report, we present a novel coaxial design in which both upper and lower rotors are contained within a ducted fan, the speeds of both rotors are independently controlled, and the lower rotor's cyclic pitch is controlled through a swashplate. Based on this design, a simple dynamic model was developed with unique force and moment generation equations. Given this model, we are able to map desired force and moment values to the control inputs capable of producing them. Afterwards, position and attitude control were implemented over this nonlinear dynamic model in simulation, such that the vehicle was able to recover from poor initial conditions and follow desired trajectories. As demonstrated by the examples presented in this report, position control results in simulations with low max percent overshoot and reasonable settling times. These results prove promising for the implementation of position and attitude control on our physical system.