Hinfinity Optimal Control For The Attitude Control And Momentum Management Of The Space Station

The objective of this research is to use the H[subscript infinity] optimality criterion to design a controller for the linearized set of Space Station dynamics equations. Besides studying the various closed-loop properties of the resulting linear system, we would like to examine the robustness properties of this controller i.e. how well it performs in the presence of unmodelled dynamics, non-linearities and disturbances. Furthermore, we will compare and contrast the control action of the H[subscript infinity] controller with that of the LQR controller."

A robust H-infinity control design methodology and its application to a Space Station Freedom (SSF) attitude and momentum control problem are presented. This approach incorporates nonlinear multi-parameter variations in the state-space formulation of H-infinity control theory. An application of this robust H-infinity control synthesis technique to the SSF control problem yields remarkable results in stability robustness with respect to moments of inertia variation of about 73 percent in one of the structured uncertainty directions. The performance and stability of this robust H-infinity controller for the SSF are compared to those of other controllers designed using a standard linear-quadratic-regulator synthesis technique. Wie, Bong Unspecified Center NCC9-16; RICIS PROJ. MS-03...

The Inertial Hold Mode (IHM) is one mode of the attitude control system of the X-ray Timing Explorer spacecraft that is disturbed by both parametric uncertainties and external torque disturbance. The IHM model is modified into a typical H-infinity mixed-sensitivity problem through choosing suitable weighting functions W(sub 1)(s) and W(sub 3)(s). The controller is designed by the H-infinity optimization technique with the transformation of shifting the imaginary axis. It can stabilize the plant with uncertainties from the natural frequencies of the flexible body. The gain margin and phase margin of the system are 24.03 db and 55.04 deg, respectively. The step response attenuates to zero within 150 seconds. These show that the controller satisfies the specified requirements. Since the order of the controller appears high, it is reduced to fourth order one. The results show that the stability and the performance of the system with the reduced controller are retained perfectly. Xu, Zhong Ling and Zhou, Gui AN Unspecified Center NAG5-2210...