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The sliding mode control (SMC) scheme is proposed for near space vehicles (NSVs) with strong nonlinearity, high coupling, parameter uncertainty, and unknown time-varying disturbance based on radial basis function neural networks (RBFNNs) and the nonlinear disturbance observer (NDO). Considering saturation characteristic of rudders, RBFNNs are constructed as a compensator to overcome the saturation nonlinearity. The stability of the closed-loop system is proved, and the tracking error as well as the disturbance observer error can converge to the origin through the Lyapunov analysis. Simulation results are presented to demonstrate the effectiveness of the proposed flight control scheme.

In this paper, we consider the robust adaptive tracking control of uncertain multi-input and multi-output (MIMO) nonlinear systems with input saturation and unknown external disturbance. The nonlinear disturbance observer (NDO) is employed to tackle the system uncertainty as well as the external disturbance. To handle the input saturation, an auxiliary system is constructed as a saturation compensator. By using the backstepping technique and the dynamic surface method, a robust adaptive tracking control scheme is developed. The closed-loop system is proved to be uniformly ultimately bounded thorough Lyapunov stability analysis. Simulation results with application to an unmanned aerial vehicle (UAV) demonstrate the effectiveness of the proposed robust control scheme.Index Terms-Nonlinear system, unmanned aerial vehicle (UAV), input saturation, disturbance observer, backstepping control, dynamic surface control (DSC).

In this paper, the fault tolerant control scheme is proposed for near space vehicles (NSVs) with system uncertainty, unknown external disturbance, actuator faults and input saturation based on the sliding mode control (SMC). To eliminate the effect of external disturbance and system uncertainty, the nonlinear disturbance observer (NDO) is designed. Neural networks are employed to deal with actuator faults. Considering input saturation, a compensated tern is constructed in the control law. The stability of the closed-loop system is proved and all closed-loop signals are uniformly ultimately bounded via Lyapunov analysis. Simulation results are given to demonstrate the effectiveness of the developed fault tolerant control scheme.