Robust Optimal Attitude Controller for MIMO Uncertain Hexarotor MAVs: Disturbance Observer-Based

• Published in: Mathematical problems in engineering 2016-01, Vol.2016 (2016), p.1-24
• Main Authors: Nonami, Kenzo, Zamzuri, H., Derawi, Dafizal, Salim, Nurul Dayana, Abdul Rahman, Mohd Azizi
• Format: Article
• Language: English
• Subjects: Attitude control; Closed loop systems; Closed loops; Control systems design; Controllers; Coupling; Design engineering; Disturbance observers; Disturbances; Dynamical systems; Embedded systems; Feedback control; Hovering; Hovering flight; Linear quadratic regulator; Mathematical problems; Micro air vehicles (MAV); MIMO (control systems); Nonlinear control; Nonlinear dynamics; Optimization; Robust control; Uncertainty
• ISSN: 1024-123X; 1563-5147
• DOI: 10.1155/2016/3154842

This paper proposes a robust optimal attitude control design for multiple-input, multiple-output (MIMO) uncertain hexarotor micro aerial vehicles (MAVs) in the presence of parametric uncertainties, external time-varying disturbances, nonlinear dynamics, and coupling. The parametric uncertainties, external time-varying disturbances, nonlinear dynamics, and coupling are treated as the total disturbance in the proposed design. The proposed controller is achieved in two simple steps. First, an optimal linear-quadratic regulator (LQR) controller is designed to guarantee that the nominal closed-loop system is asymptotically stable without considering the total disturbance. After that, a disturbance observer is integrated into the closed-loop system to estimate the total disturbance acting on the system. The total disturbance is compensated by a compensation input based on the estimated total disturbance. Robust properties analysis is given to prove that the state is ultimately bounded in specified boundaries. Simulation results illustrate the robustness of the disturbance observer-based optimal attitude control design for hovering and aggressive flight missions in the presence of the total disturbance.