Model Predictive Tracking Controller for Quadcopters with Setpoint Convergence Guarantees

This paper tackles the trajectory tracking problem for a quadrotor following a cascaded control design approach; an outer-loop model predictive controller (MPC) generates acceleration references to be tracked by an inner-loop nonlinear attitude controller. Leveraging the differential flatness property of the quadrotor's dynamics, the proposed model predictive controller uses a linear third order model for prediction, enabling the attitude controller to track exactly the sufficiently smooth virtual acceleration while coping with state and input constraints. Asymptotic stability is established for the regulation problem for any initial position and velocity. In other words, the quadrotor provably tracks any setpoint reference. Simulations of the proposed cascade system are performed to validate and assess the convergence properties.