Dynamic Modeling and Control of a Quadcopter with Longitudinal-Tilting Rotors
Henrique Bezerra Diógenes1; Davi Antônio dos Santos1
1 Instituto Tecnológico de Aeronáutica
doi:10.20906/CPS/CILAMCE2017-1157
Resumo
Conventional multirotor aerial vehicles require a controlled attitude motion in order to suitably direct the resulting thrust force for position tracking. Occasionally, a wide attitude motion is undesirable, e.g., for maintaining a camera with its optical axis almost aligned with the local vertical, or for saving energy when dealing with high-inertia vehicles. In this context, the present paper investigates a quadrotor vehicle with rotors that can be continuously commanded to tilt in one degree of freedom, frontward and backward. In particular, we are concerned here with the dynamic modeling and flight control design for the new multirotor vehicle. To model the vehicle's dynamics, this work adopts the Newton-Euler approach, considering its motion in six degrees of freedom and accounting for a first-order dynamics in the tilting mechanism. The flight control system is designed based on the time-scale separation between the attitude and position dynamics, being the first the fastest one. In this case, the attitude and position control laws are designed separately using feedback linearization combined with proportional and derivative actions and control saturation. Finally, we generate the commanded trajectory so as to make the vehicle follow a waypoint-based path with a desired speed and with its longitudinal axis pointing toward the next waypoint of the sequence. An extensive simulation study is carried out to assess the dynamics behavior of the new multirotor vehicle on different desired speed and tilting mechanism dynamics. The results show that the vehicle can be effectively controlled to stay almost aligned with the horizontal plane during all the trajectory.
Palavras-chave: Multirotor aerial vehicle; Flight control system; Nonlinear control