Mars Atmospheric Entry Guidance using MPSP with State and Control Constraints

Abstract

An optimal Mars entry guidance scheme is presented in this paper using the Model Predictive Static Programming (MPSP) technique accounting for the applicable state and control constraints. The guidance scheme is designed to maximize the terminal parachute deployment altitude while applying minimum control effort and satisfying hard constraints on desired terminal conditions such as final velocity and downrange. The proposed guidance computes the optimal bank angle profile to shape the trajectory of the spacecraft. Path constraints on heat rate, dynamic pressure, aerodynamic load, and bounds on bank angle are considered to guide the vehicle safely through the martian atmosphere. Moreover, in order to generate practically realizable bank angle profiles, an additional constraint on the bank angle rate is also applied. Next, using the MPSP technique, the nonlinear constrained optimal control problem is converted into a static quadratic optimization problem with linear equality and inequality constraints to solve it in a computationally efficient manner. The concept of flexible final time MPSP is incorporated to update the final time in an optimal fashion. Numerical simulations illustrate the ability of the proposed method to solve the guidance problem efficiently while satisfying the path and terminal constraints within the desired accuracy.