Pseudospectral feedback control based on-line trajectory reconfiguration of suborbital return

Multi-mission of Suborbital Reusable Launch Vehicle require more intelligent and robust guidance and control system. Based on pseudospectral optimal feedback control theory, the Legendre pseudospectral method is used for on-line optimal trajectory reconfiguration according to current flight states, final conditions and path constraints including dynamic pressure, normal acceleration and heat rate. Angle of attack and bank angle commands are updated through real-time feedback. The return dynamics model taking is introduced into the on-line trajectory reconfiguration changing rates of angle of attack and bank angle as virtual controls, and several strategies can ensure its real-time performance. Suborbital returm flight simulation shows that this trajectory reconfiguration scheme is capable to compensate for large disturbances including severe-case wind gusts and on-line trajectory computations can satisfy the required feedback update time. It is also shown that on-line trajectory reconfiguration can ensure smooth angle of attack and bank angle commands.