Accession Number : ADA436263


Title :   A Reconfigurable Guidance Approach for Reusable Launch Vehicles


Corporate Author : BARRON ASSOCIATES INC CHARLOTTESVILLE VA


Personal Author(s) : Schierman, J. D. ; Ward, D. G. ; Monaco, J. F. ; Hull, J. R.


Full Text : http://www.dtic.mil/dtic/tr/fulltext/u2/a436263.pdf


Report Date : 2001


Pagination or Media Count : 12


Abstract : A guidance system with reconfiguration capabilities has been developed for reusable launch vehicles (RLVs). The focus of the development is on reconfiguration after a catastrophic effector failure during final approach - a failure that would otherwise cause loss of the vehicle. We assume here that the vehicle employs a reconfigurable inner-loop control system that recovers some maneuvering capabilities and maintains attitude stability. However, for RLVs, it is often the case that nominal performance cannot be fully recovered, and the outer-loop guidance system must account for the degraded response characteristics. Two approaches are presented. The first approach augments the existing production guidance system with adaptation capabilities. A case study shows that stability is maintained following a primary pitch effector failure. However, it is shown that the trajectory commands to the guidance loops must also be re-targeted in order to achieve a safe landing. The second approach employs an on-line optimal trajectory re-targeting algorithm. A database of neighboring optimal trajectories is encoded in an efficient manner and interrogated on line at regular intervals. Given the current states and certain vehicle parameters, this procedure generates optimal guidance commands and integrates the optimal trajectory to the next update point. A proof-of-concept study of this approach was performed. Following a primary speed control failure, the study shows that this approach achieves acceptable landing conditions.


Descriptors :   *GUIDANCE , *LAUNCH VEHICLES , MANEUVERABILITY , LOOPS , ATTITUDE(INCLINATION) , SPEED REGULATORS , TRAJECTORIES , REUSABLE EQUIPMENT.


Subject Categories : NAVIGATION AND GUIDANCE
      UNMANNED SPACECRAFT


Distribution Statement : APPROVED FOR PUBLIC RELEASE