Powered Descent Guidance Using a Tunable Segmented Acceleration Profile

To enhance the analytical guidance for the powered descent with multiple constraints, a guidance method using a tunable segmented acceleration profile is developed. With three segments and 12 tunable parameters, the acceleration profile is successively designed for fuel-efficiency and obstacle avoidance. The appropriate one of these two profiles is chosen according to the feasible region of the segment points under the constraints of thrust and glide-slope angle. For the chosen profile, the segment points are solved by a simplified optimization problem, and the tunable parameters are selectively modified onboard in three phases to obtain the guidance commands for pin-point landing. The proposed guidance method is verified by the simulation of an asteroid landing mission. Results indicate that the guidance method can take the thrust constraint, the obstacle avoidance requirement, and the fuel consumption into account, while requiring less computational cost. Moreover, with the tunable parameters, the guidance method can improve the landing precision and extend the controllable zone of the initial position.