A control-oriented dynamic model of tiltrotor aircraft for urban air mobility

This paper aims at developing an analytical flight dynamic formulation for urban air mobility (UAM) vehicles. Such vehicles feature tiltrotors for vertical takeoff/landing and fixed-wings for level flight. In this analytical formulation, a nonlinear rigid-body dynamic model is enhanced by incorporating multiple tiltrotor dynamics and their gyroscopic and inertial coupling effects. A quasi-steady aerodynamic formulation is implemented to calculate the aerodynamic loads on all lifting surfaces. In addition to the conventional control surfaces of the fixed-wing aircraft, such as elevator, aileron, and rudder, both tilt angle and rotational speed of each rotor are considered the control inputs in the formulation of nonlinear flight dynamics. These nonlinear dynamics are then linearized with respect to a set of trimmed flight conditions of interest to render the corresponding linear time-invariant state-space models used to create a linear parameter-varying (LPV) model as a function of flight condition (tilting). Adaptive MPC (model predictive control) methodology is then used to design controllers to achieve smooth tilting transition with simulation validation.