Trajectory Planning of Longitudinal Transition Flight and Quasi-Linear Parameter-Varying-Model Predictive Control Tracking Control for Tilt-Rotor VTOL Aircraft

Abstract This paper presents an optimal trajectory planning and tracking control framework for a tilt-rotor Vertical Take-Off and Landing (VTOL) aircraft during longitudinal transition flight. Specifically, the Multiple Shooting Method (MSM) is employed to generate a flight trajectory that consists of takeoff, transition, and level flight. Unlike prior works, MSM yields a dynamic flight trajectory rather than a quasi-equilibrium trajectory. After that, a Linear Parameter-Varying (LPV) Model Predictive Control (MPC) scheme is developed to track the dynamic trajectory. The linear parameter-varying-model predictive control (LPV-MPC) scheme efficiently accounts for varying nonlinearities by previewing the scheduling parameters (velocity, pitch rate, and rotor tilting angle) along the dynamic flight trajectory. The LPV-MPC formulates a convex optimization problem 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 evaluated in simulation scenarios of initial state error and measurement noises. Furthermore, the LPV-MPC is compared with nonlinear MPC and further validated in hardware-in-the-loop (HIL) experiment with excellent tracking performance and computational efficiency for real-time implementation.