AAS 97-180

ON-OFF CONTROL TO DESPIN AND RETRIEVE A TETHERED ARTIFICIAL GRAVITY SPACECRAFT INCLUDING PASSIVE DAMPING

S. I. Saeed and J. D. Powell, Stanford University

Abstract

This paper develops optimal on-off thrusting profiles to despin and retrieve a tethered artificial gravity spacecraft. A nonlinear on-off thrusting optimization is performed on a simple 3-DOF system. Fuel usage for on-off thrusting is compared to a continuous thrusting case and found to be slightly better compared to previous results. The nonlinear optimized thrusting profile is applied to a three segment tether model with constant passive damping and found to be unstable during retrieval. By increasing the retrieval time and stopping thrusting for low tether tensions, the tether retrieval is stabilized for tether lengths greater than 25 meters.