Fixed ground-target tracking control of satellites using a nonlinear model predictive control

Abstract

This paper proposes a novel solution to the fixed-ground target tracking control problem of satellites utilizing a Nonlinear Model Predictive Control approach (NMPC). The Continuation / Generalized Minimal Residual (C/GMRES) algorithm is selected as a promising fast solver to an optimal control problem in real time. The algorithm could perfectly deal with the huge computational load of this approach, represented in solving Riccati differential equation, by simple and efficient approximations. A new control-oriented model converting the main tracking problem into a simple regulation problem is developed. This simple and easy traceable reformulated model has an advantage in dealing with modeling errors and unplanned external environmental disturbances. The update of the control input is obtained by integrating a deduced time-dependent inputs and Lagrange multipliers vector; representing the solution of a set of linear equations and corresponding to the optimality conditions. The proposed algorithm is simulated using real satellite parameters to track a fixed-ground target for reconnaissance purposes. The simulation results show that the algorithm of C/GMRES method can track a desired fixed ground target robustly, with precise tracking error and guaranteed safe stability limits for shooting activities throughout the overpass flight. � 2017 IIETA.