Trajectory Planning of Longitudinal Transition Flight and Quasi LPV-MPC Tracking Control for Tilt-Rotor VTOL Aircraft

This paper presents an optimal trajectory planning and tracking control of tilt-rotor Vertical-Take-Off-and-Landing (VTOL) aircraft in longitudinal transition flight. Specifically, the Multiple Shooting Method (MSM) is employed to generate a flight trajectory that consists of taking off and transitioning to level flight. Unlike prior works, MSM renders a dynamic flight trajectory rather than quasi-equilibrium trajectories. After that, Linear Parameter-Varying (LPV) Model Predictive Control (MPC) is developed to track the dynamic trajectory. The LPV-MPC method can efficiently account for varying nonlinearities by previewing the scheduling parameters of velocity, pitch rate, and rotor tilting angle along the dynamic flight trajectory. The LPV-MPC formulates a convex optimization that minimizes the weighted tracking error and control inputs while satisfying constraints of states and control inputs. The proofs of stability and recursive feasibility are also presented. The tracking control is validated and evaluated in the simulation scenarios of initial state error and measurement noises. Furthermore, the LPV-MPC is compared with nonlinear MPC, which demonstrates that LPV-MPC can render comparable tracking performance but with significantly reduced computations than nonlinear MPC.