Robust Fault-tolerant Control for Quadcopter UAVs Using LMPC and INDI

This paper proposes a robust fault-tolerant control (FTC) framework (I-LMPC), for quadcopter unmanned aerial vehicles (UAVs) by integrating Linear Model Predictive Control (LMPC) with Incremental Nonlinear Dynamic Inversion (INDI). While the LMPC system constraints and generates optimal reference commands, its performance degrades under strong nonlinearities and model uncertainties. To address this limitation, a dual-loop architecture is introduced, where LMPC operates in the outer loop to provide optimal attitude and altitude references, and INDI functions in the inner loop to ensure high-frequency disturbance rejection and robustness against actuator faults. The approach is validated through MATLAB/Simulink simulations using a 6-DOF nonlinear quadcopter model. Results show that under a 40% loss of effectiveness (LOE) in a rotor, the proposed method maintains accurate trajectory tracking and stable attitude control, outperforming standalone LMPC and preventing system instability.