Robust control for reentry vehicles based on block backstepping

This paper proposes a robust nonlinear control law based on input-to-state stability (ISS) and block backstepping for reentry vehicles. Considering the model uncertainties and external disturbances, the model of Six-Degree-of-Freedom (6DOF) Reusable Launch Vehicles (RLV) is transformed into a strict-feedback system, and the block backstepping is applied to design the control law which can make the attitude angles track the desired values (guidance commands). The stability analysis shows that the track errors can converge into a small neighborhood of zero in presence of the uncertainties and disturbances. Finally, the algorithm is tested using computer simulations.