Abstract: A novel robust active disturbance rejection control approach is presented for a reusable launch vehicle during reentry. The state variables of a general multiinput multioutput model are redefined so that the linear extended state observers of every channel can be designed separately. Then a robust analysis and design methodology is proposed for the active disturbance rejection control system. When this methodology is applied to attitude control, the attitude command is filtered by the steepest tracking differentiator to deal with the contradiction between response speed and antiwindup performance during bank reversal. Simulation results show that the designed control system is well decoupled and quite robust and the saturation problem is solved.

Key words: robust, active disturbance rejection control, antiwindup, decoupling