Extended State Observer-Based Integral Control Barrier Functions for State/Input Constrained Control of Nonaffine Flight Vehicle Model

During the flight of an air-breathing hypersonic vehicle, strict constraints on control surface deflections and flight states are crucial for engine stability, flight accuracy, and overall system stability. This article proposes a robust constrained control strategy that integrates dynamic inversion (DI) control, integral control barrier functions (ICBFs), and an extended state observer (ESO) to enhance disturbance rejection capability and ensure state and input constraints. First, a nonaffine nonlinear dynamic model is established, with ESO for disturbance estimation. Following a backstepping design, a command filter mitigates the xplosion of complexity and the final step employs DI to handle the nonaffine control problem. Then, an ESO-based ICBF (ESO-ICBFs) method is proposed to integrate state and input constraints within a unified control framework, ensuring system safety and optimal performance. Unlike traditional approaches that enforce constraints separately, this method encodes these constraints holistically within a single framework via ICBF and employs quadratic programming to compute an auxiliary control input that modifies the original DI-integral control law, thereby formulating a constrained control law. This minimally invasive constraint-enforcement strategy ensures that the vehicle operates along constraint boundaries, fully utilizing its maneuverability while maintaining safety. Importantly, the disturbance estimation provided by ESO reduces reliance on worst-case disturbance estimates, avoiding unnecessary control effort. Finally, rigorous stability and safety analysis guarantee that the tracking error of the nonaffine hypersonic vehicle system remains uniformly ultimately bounded, and that state and input constraints are always satisfied. Numerical simulations validate the effectiveness of the proposed nonaffine attitude control method in ensuring state/input safety.