# Optimal Trajectory Planning for Multiphase Lunar Landing

Mathavaraj, S and Pandiyan, R and Padhi, R (2016) Optimal Trajectory Planning for Multiphase Lunar Landing. In: 4th IFAC Conference on Advances in Control and Optimization of Dynamical Systems (ACODS 2016), FEB 01-05, 2016, Tiruchirappalli, INDIA, pp. 124-129.

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Official URL: http://dx.doi.org/10.1016/j.ifacol.2016.03.040

## Abstract

Lunar landing problem is formulated as an optimal control problem and has been solved by Legendre Pseudospectral method. The landing problem is split into various stages to take into account various mission constraints. Based on These constraints, the problem is split into three stages Hough Braking, Attitude Hold and Retargeting Legendre Pseudospectral method is used for solving this multiphase lunar landing problem. The idea of this method is to discretize the trajectory optimization as a nonlinear programming problem. Legendre Pseudospectral method was applied to approximate the state and the state differential equations as algebraic constraints. Optimal solutions of the above problem are those control variables which dynamically satisfy all mission constraints. The cost function considered is minimum fuel satisfying all mission constraints envisaged. The method guarantees a null (Mann fuel solution which satisfies terminal mission constraints in each stage as part of the formulation. The mission constraints considered in studying this problem are desired altitude, attitude and velocity while reaching the desired landing site from a specified perilune height. At touchdown, the lander orientation should be vertical favoring landing leg of the Lander to touch the Moons surface as desired. The commanded acceleration should be within the limit of the main engine thruster capability (saturation limit) which enforces maximum and minimum thrust constraints. (C) 2016, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.

Item Type: Conference Proceedings IFAC PAPERSONLINE ELSEVIER SCIENCE BV Copy right of this article belongs to the ELSEVIER SCIENCE BV Lunar Landing; Legendre Pseudospectral; Optimal Control; Nonlinear Programming Division of Mechanical Sciences > Aerospace Engineering(Formerly Aeronautical Engineering) 20 Jul 2016 08:56 20 Jul 2016 08:56 http://eprints.iisc.ac.in/id/eprint/54218