Reference Tracking of Quadrotor Using Modified Nonlinear Model Predictive Control Based on Nonlinear Disturbance Observer

This paper proposes a modified nonlinear model predictive control based on nonlinear disturbance observer (NDO-NMPC) for reference tracking of a quadrotor. The quadrotor model is nonlinear with a multi-input-multi-output (MIMO) system type. This study’s discussed problem is requiring a quadrotor to track the given trajectories. The disturbances considered in the system are constant and step disturbances. The unknown disturbances are estimated using a nonlinear disturbance observer. Furthermore, the disturbance estimations are added to the system’s prediction of NMPC. Based on the simulation results, the NDO can provide good estimation results for estimating the system disturbances. According to the performed numerical simulations, the optimal inputs obtained satisfy the limitations of the defined constraints. In addition, the proposed NDO-NMPC can overcome external disturbances, so the outputs of NDO-NMPC are appropriate for the expected results.