Attitude control law design for a flight vehicle with output boundary protections

An attitude control law is developed for a flight vehicle using backstepping and adaptive control methods. High-pass filters are used to estimate the time derivatives of control signals required in the control law. This approach reduces the need for analytical or numerical time derivatives of control signals in traditional backstepping controllers. Furthermore, an output boundary protection control law is designed using the projection operator method, with superellipse curves defining control boundaries to match specified boundaries in multivariable controls. To demonstrate the stability of the closed-loop system governed by the proposed control law, Lyapunov stability theories have been applied. Additionally, the technical issue of coupling between high-pass filters and the stability of the closed-loop system has been resolved. Numerical simulations are carried out to assess the control performance, and the results show that the proposed control law achieves the desired pitch command tracking and turn coordination command tracking performance for the vehicle, along with meeting the output boundary protection requirements for the angle of attack and angle of sideslip.