Decentralized Robust Optimal Control of Large Flexible Space Structures by Fourth Order Local Proper Controllers Using Displacement Output

Abstract

This paper considers position and attitude control of large flexible space structures composed of a number of subsystems(substructures) under the assumption of sensors and actuators collocation. The purpose of this paper is to propose a decentralized control scheme with fourth order local proper controllers using displacement/angle output, which makes both each closed-loop subsystem and an overall closed-loop system not only robustly stable but also optimal for quadratic cost functions. We first introduce a fourth order local proper controller for stabilizing each subsystem using only displacement/angle output. Then, we show each closedloop subsystem becomes not only robustly stable against uncertain characteristic parameters such as mass, damping, and stiffness, but also optimal for a quadratic cost function by choosing parameters of each local proper controller appropriately. After stabilizing and optimizing each subsystem, we interconnect the closed-loop subsystems by flexible links to obtain an overall closed-loop system, and we show the overall closed-loop system also becomes robustly stable and optimal for a quadratic cost function. Finally, numerical examples are presented to show effectiveness of the proposed method.