Dynamics, Control and Maneuvering of Large Flexible Space Tethered Reflectors, Tele-Robots and Experimental Models. Part 2.

The effects of solar radiation heating on a large, thin, shallow spherical orbiting shell system are studied. The shell is representative of a large antenna reflector system which could also be gravitationally stabilized by connecting a sub-satellite to a long tether. After determining the steady state temperature distribution across the thickness of the shell, the corresponding thermal deformation is estimated as a function of the solar incidence angle and material properties. The closed-loop dynamic response of the shell is simulated by using LQR control design synthesis and assuming that 12 point actuators are placed on the outer surface and edge of the shell. Calculations also indicate that the shells transverse elastic vibrational frequencies may differ significantly from their nominal values due to the solar-thermal influence. A practical control strategy for the minimum-time maneuver problem has been developed and successfully applied to the Naval Research Laboratorys Reconfigurable Spacecraft Host for Attitude and Pointing Experiments RESHAPE hardware test facility. This is the first time that the bang-bang type and feedback control strategy has been applied to the RESHAPE facility by including a flexible appendage which is represented with the attachment of a spherical pendulum device to the edge of the RESHAPE platform. MM