Dynamic modeling of a robotic spacecraft for NASA’s asteroid redirect robotic mission

Abstract

NASA’s Asteroid Redirect Robotic Mission (ARRM) aims to pick up a boulder from the surface of a large asteroid and transport it to a distant retrograde orbit around the Moon for future exploration by a manned mission. This thesis presents a detailed analysis of the dynamic modeling of the ARRM spacecraft grasping the boulder. This model is used for three-axis attitude control design and simulation of the system. This thesis presents a 30 degree-of-freedom nonlinear lumped-mass model for the structural dynamics of the spacecraft-boulder system. This model is derived using the Euler-Lagrange formulation and simulated in the Matlab-Simulink environment. Another model is derived using Kane’s formulation and SD/FAST, a software package dedicated to deriving dynamic models. Both models are linearized numerically about an equilibrium point. The frequency domain analysis of these linearized models is presented to understand the system behavior and dominant modes. Both models are compared to each other and to an independently developed finite-element model to validate the modeling approach.