EMPC-Based Flight Controller Design for a Quadrotor with Unbalanced Payload

In this paper, a robust explicit model predictive control (EMPC) flight scheme is investigated for a quadrotor. MPC is widely recognized for its effectiveness in control, but its computational complexity for solving the online optimization problem, particularly for fast systems, poses a challenge. To address this, we introduce an innovative inner-outer loop control structure that incorporates EMPC which can transfer the overall optimization process offline. In the outer loop, we calculate reference roll and pitch angles, while the inner loop employs EMPC for rapid and optimized angle tracking within practical constraints. Additionally, integral sliding mode control (ISMC) is integrated to mitigate the effects of unbalanced pay-loads. The recursive feasibility is guaranteed for the proposed flight control method if the initial states are in the feasibility set, and the Lyapunov stability analysis is conducted. Finally, experiments show the efficacy of the proposed control strategies.