On-Line Trajectory Command Reshaping for Reusable Launch Vehicles

Abstract

To enable autonomous operations in future Reusable Launch Vehicles (RLVs), onboard trajectory command reshaping will be required to facilitate recovery of the mission following a major anomalous event such as an effector failure. The Optimum-Path-To-Go (OPTG) on-line trajectory-reshaping algorithm is presented. In the OPTG methodology, a trajectory database is precomputed off-line covering all variations under consideration. Then, polynomial-based networks are generated which map these variations to basis function coefficients that describe the shape of the trajectories. The networks are then interrogated on-line, and the resulting coefficients are used to generate trajectory commands. Thus, based on the current state of the system, the algorithm will reshape the commanded trajectory to give the best remaining path to the end of the mission segment. For this study, the commanded trajectory was reshaped on-line due to a severe multiple control surface failure. Without reshaping, the vehicle is lost, even with control reconfiguration and guidance adaptation. With trajectory reshaping, the mission is recovered.