Autonomous and Integrated Guidance, Navigation, and Control System for Fuel-optimal Atmospheric Entry, Descent, and Landing Maneuver

Abstract

In the history of mankind, observation and exploration of the universe have been continuously developed, and the curiosity of mankind about the unknown world will not cease. We have been sending exploration vehicles to an unknown planet beyond just looking, and we are looking forward to manned Mars landing probes like human-crewed lunar landings. It is essential to develop the entry, descent, and landing (EDL) system with autonomous capabilities to realize this. Therefore, the autonomous and integrated guidance, navigation, and control (GNC) system for fuel-optimal atmospheric EDL maneuver is designed, developed, and proposed in this study. The challenges facing the EDL system development are associated with increased landed mass capability, improved landed accuracy, and landing at the desired altitude. Also, to safely land on Mars' surface, the kinetic energy of the lander must be used up perfectly and safely. However, Mars' atmosphere imposes difficulties for a safe landing. A fuel-optimal trajectory must be developed, and the desired altitude and velocity at the landing site with consideration of Mars' atmosphere characteristics must be achieved to overcome these difficulties. For this, in this study, semi-analytical solutions to the optimal control problem for 3-dimensional fuel-efficient planetary landing trajectories with constant exhaust velocity and limited mass-flow rate in a drag-existing central Newtonian field are presented. The first-order optimality conditions reduce the problem to a Hamiltonian canonical system to design and synthesize feasible and extremal planetary EDL trajectories. The proposed solutions allow us to describe the state vector and Lagrange multipliers in terms of time and characteristics of switching function to determine the number and sequence of thrust arcs. These solutions describe new extremal trajectories based on the analysis of first- and second-order optimality conditions. The results of this work can be used to support mission design analysis and synthesis of fuel-efficient trajectories. For the autonomous capability, the GNC system was integrated with the proposed EDL trajectories. An extended Kalman filter (EKF) was applied to estimate the position and velocity components as the navigation solutions, and these estimated components were used to the E-guidance as the guidance solutions. Therefore, the feasibility of the autonomous and integrated GNC system for the proposed EDL maneuver was demonstrated. These solutions can be adjusted for maneuvers near other celestial bodies for which a central gravitational acceleration can be dominant. Also, the results of this work can be used to support mission design analysis, and the next generation of missions aim to perform autonomous and precision landing maneuvers, which impose significant challenges on the development of lander's autonomous control and guidance systems.