Tracking control for nonminimum phase MIMO micro aerial vehicle – a dynamic sliding manifold approach

Nonminimum phase output tracking has been addressed for a fixed-wing micro aerial vehicle. Nonminimum phase characteristics in an aircraft result from the fact that the process of generating upward vertical motion produces an initial downward force, causing the aircraft to lose altitude momentarily, and vice versa. This phenomenon leads to unstable internal dynamics in the plant model. A dynamic sliding-surface-based sliding mode control is chosen to stabilize the internal dynamics and to provide asymptotic output tracking error convergence to zero with desired eigenvalue placement. The control is designed in such a way that the output of the plant model should track a nonlinear time-varying reference trajectory generated at every time instant with a finite number of nonzero time derivatives. Design of second-order sliding-mode-based super twisting controller which ensures finite-time stability of the internal dynamics is proposed in this work. The proposed control methodology is applied in the design of an autolanding controller for a micro aerial vehicle with nonminimum phase behavior. MATLAB-based simulation results and discussions are presented to evaluate the performance of the controller and robustness of the sliding mode with respect to matched and unmatched disturbances. The proposed control algorithm has been successfully implemented in hardware-in-the-loop simulation and results are given.