An Improved Nonlinear Observer-Based Integrated Guidance and Control for Hypersonic Flight Vehicle with Angle Constraints

This paper presents the results of an improved integrated guidance and control (IGC) design method for a nonlinear uncertain hypersonic flight vehicle (HFV) with angle constraints is presented based on an adaptive block dynamic surface control scheme, backstepping method, and a multivariable nonlinear disturbance observer (NDOB) in three-dimensional space. Initially, the integrated guidance and autopilot dynamic model, encompassing six degrees of freedom (6DOF), is established by amalgamating the HFV dynamic model with the HFV-target relative motion model. This formulation takes into account uncertainties in aerodynamics and modeling, as well as the impact of cross-coupling effects and disturbances. To apply the nonlinear, disturb observer-based based control (NDOBC) method, a multivariable chattering-free NDOB is used to estimate the lumped uncertainties in the established integration and autopilot model. It should be noted that an adaptive block dynamic surface control approach in combination with a backstepping method is presented to achieve high performance in the target interception, state regulation, and regulation of azimuth and elevation angles related to the line of sight (LOS). Closed-loop stability, estimation errors convergence to zero, and state regulation are proven based on the Lyapunov theory. Moreover, the simulation results demonstrate the effectiveness of the proposed NDOBC approach. It not only ensures closed-loop stability but also achieves high-performance target interception with smooth control inputs.