Dynamic Analysis and Control Design for a Tiltable Quadrotor This paper presents a tiltable quadrotor that can independently control position and attitude. Firstly, the dynamic modeling of the system is carried out. We adopted a nonlinear separation strategy for the nonlinear strong input problem existing in the system. We separated the nonlinear system into a linear dynamic link and a nonlinear static link by constructing an intermediate control quantity. Then, linear quadratic regulator with small calculation and easy hardware implementation was designed only for a linear dynamic link while real control, including tilting angle and motor speed, was mapped from intermediate control by calculating the input nonlinear static link. The simulation shows that the designed nonlinear controller based on nonlinear separation and LQR can stably control the tilting quadrotor and can independently track the position and attitude expectations.

Mathematical modeling and control of a quadrotor aerial vehicle with tiltrotors aimed for interaction tasks With a wide spectrum of applications ranging from entertainment to military use, quadrotors, in their conventional construction with four fixed rotors, have proven to be sufficiently capable of robustly performing numerous tasks. However, the capability to generate thrust just in one direction, i.e., normal to its main plane, is very restrictive and drastically reduces the maneuverability and agility of the vehicle. In this paper, an alternative model of the quadrotor is presented. Constructively, the difference lies in the addition of a mechanism that tilts the rotors in the longitudinal direction, which in practice adds maneuverability by enabling the longitudinal translation uncoupled from the pitching movement. In addition to this new thrust component in the longitudinal direction, this configuration also yields a significant increase in the yaw torque. These are highly desired features in a UAV used to execute tasks that require physical interaction with the surrounding environment. The mathematical model of the entire system is obtained by employing the EulerLagrange formalism and a multibody approach. In addition, a basic control scheme is used to verify, through simulation, the obtained model.