EXPERIMENTAL VERIFICATION OF ATTITUDE CONTROL TECHNIQUES FOR SLEW MANEUVERS OF FLEXIBLE SPACECRAFT

This paper presents experimental verification of modern and classical control laws on flexible spacecraft structures. The Flexible Spacecraft Simulator at the Naval Postgraduate School is designed to test a variety of control theory on a two-dimensional representation of an antenna at the end of a low-frequency astromast. The Simulator represents motion about the pitch axis and is restricted to rotatation only. Control laws are implemented through a momentum wheel mounted on the rigid main body. Feedback is obtained through a rotary variable differential transformer (RVDT) which senses the body's rotation angle and a rate-gyro giving body rate. The analytical model contains the linearized equations of motion accounting for the flexible dynamics. Slewing maneuvers are conducted for positioning the main body by using proportional-derivative (PD), torque profiles and optimal controllers. No active control is applied to the flexible structure. A new technique for state estimation is developed for the optimal controller since the standard estimation methods prove to be unsatisfactory. In all cases, the experimental results are in close agreement with the analytical predictions