Improved Parallel-Structured Newton-Type Guidance for Launch Vehicles Under Thrust Drop Fault

When launch vehicles encounter thrust drop f4aults during endoatmospheric flight, conventional nominal trajectory-based guidance methods may fail to compensate adequately; and the launch mission may culminate in failure. In this paper, we present an improved parallel-structured Newton-type guidance (PSNG) algorithm to address the aforementioned challenge. Compared to the basic PSNG algorithm, the proposed algorithm entails two major improvements: determination of the free final time and handling of the path constraint using the projected Newton-type method. Except for inheriting the benefits of the original PSNG algorithm, the improved algorithm can solve the free-final-time and path-constrained ascent guidance problems directly. Numerical simulations with various ascent scenarios of thrust drop faults are conducted, and the results show that the improved algorithm has high computational efficiency, accuracy, and robustness against disturbances and uncertainties.