Nonlinear Model Predictive Control of Tilt-Rotor UAV Under A Dual Differential Model Based on INDI Strategy

This paper proposes a new tilt-rotor UAV (TRUAV) that integrates the hovering capabilities of quadrotors with the long-range flight benefits of fixed-wing aircraft. Designed with a dual differential rotor architecture, this TRUAV enhances energy efficiency and obstacle avoidance capabilities. Given the challenges posed by the TRUAV’s highly coupled and nonlinear dynamic characteristics in attitude and tilt angle control, a controller integrating Incremental Nonlinear Dynamic Inversion (INDI) control with Nonlinear Model Predictive Control (NMPC) has been designed. This controller achieves precise trajectory tracking and attitude control through NMPC while utilizing the INDI strategy for real-time computation of rotor tilt angles during the transition mode. To optimize energy usage and enhance maneuverability and obstacle avoidance capabilities, a novel introduction of Front-Back and Left-Right rotor differential modes has been implemented. Experimental results show that the NMPC controller based on the INDI strategy can effectively handle the complex dynamics of TRUAV and achieve efficient control performance in attitude control. Compared to the traditional PID, the proposed controller reduces the maximum pitch angle of the TRUAV during flight by 34.60%, achieving an 11.44% improvement over the conventional NMPC method.