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Nonlinear Disturbance Observer Augmented Model Predictive Attitude Tracking Control of Quadrotors

A new nonlinear disturbance observer (NDO) based generalized model predictive control approach is developed for quadrotor attitude tracking missions subject to the multiple model uncertainties including parametric uncertainties, matched and mismatched external disturbances. Based on the kinematics and dynamics of the systems, the attitude tracking controller development is divided into two sub-systems designs to facilitate dealing with the matched and mismatched uncertainties. For the attitude kinematics subsystem, the generalized model predictive method and NDO are combined to design the desired angular velocity and compensate the mismatched disturbances. For the attitude dynamics subsystem, the generalized model predictive method and NDO are integrated again to design the actual control input torques of quadrotors and compensate the matched disturbances. In particular, NDO is used to estimate the unknown disturbances, while the model predictive control is used for optimizing the desired angular velocity and the control efforts. The attitude tracking errors eventually converge to small neighborhoods of zero with the proposed control strategy, and the simulation results validate the effectiveness of the proposed approach.