Automatic load relief numerical predictor-corrector guidance for low L/D vehicles return from low Earth orbit

The poor maneuverability of low lift-to-drag ratio (L/D) vehicles results in low precision of reference-trajectory guidance and difficulty in meeting load constraints. This paper presents an automatic load relief numerical predictor-corrector method for the guidance of low L/D vehicles return from low Erath orbit. By elaborately designing a bank-angle profile in each guidance circle and selecting appropriate iteration parameters, the goal of automatic load relief is achieved, which greatly reduces the maximum peak load. With the use of coupled guidance and landing error feedback algorithms, the guidance precision is improved. Aerodynamic coefficients of the vehicle and landing errors are filtered to further increase the robustness of the algorithm. Extensive Monte Carlo simulations are conducted to evaluate and verify the design features of the algorithm. The test results show that the algorithm consistently offers very satisfactory performance even in highly dispersed cases. Such an algorithm holds distinct potential for onboard applications.