ESTIMATION AND CONTROL OF TETHERED SATELLITE SYSTEMS

This paper describes the analysis of a tethered system during the stat ion-keeping phase. The system is composed of two small satellites conn ected by a long tether. The satellites are modeled as particles, and t he tether is represented by eight rigid, massive rods. The angles betw een adjacent elements can vary with time. Only measurements at the end bodies are considered, and the angles between the tether segments are estimated by using a reduced-order estimator. The compensator design is based on the linear quadratic regulator algorithm and a steady-stat e Kalman fitter. It is shown that all motion modes are observable with the available measurements and controllable with thrusts on one of th e satellites.