Robust adaptive attitude control of reentry vehicle with input constraint and uncertainty

A nonlinear robust adaptive backstepping attitude controller is designed for a reusable launch vehicle in reentry phase under input constraint, model uncertainty and external disturbance. for the couplings between the translational and rotational motions, a control-oriented model (COM) with uncertainty is firstly derived to succinctly design controller. It is worth pointing out that the uncertain terms in the COM do not need to satisfy linear parameterization assumption, and their upper bounds do not need to be known in advance. The robust adaptive laws are developed to estimate the upper bounds online. To facilitate analytic computation for the time derivative of virtual control input, a second-order filter is employed to estimate it. An additional system is constructed to handle input constraint. By rigorous analysis, the tracking error is guaranteed to converge to a random neighborhood around zero by appropriately choosing parameters. At the end, the effectiveness of the designed controller is shown by compared simulations.