In this paper a model of a hypothetical flexible spacecraft that resembles French multi mission satellite SPOT is selected. This model represents a multivariable system that is difficult to control due to strong cross couplings. | Journal of Automation and Control Engineering Vol. 6, No. 1, June 2018 Command Shaped Robust Control of a Flexible Spacecraft Waseem A. Butt Department of Electrical Engineering, College of Electrical and Mechanical Engineering, Rawalpindi, Pakistan Email: butt_waseem@ for flexible space structures must meet tight performance requirements while being robust to model uncertainties. Conventional control methods have been used very effectively to control a wide variety of systems. These methods are time tested and are presently being used in most of the industries. In order to carry out analysis of multivariable systems that are coupled, conventional control methods are not so easily manageable. Extensive research has been focused on control of flexible multivariable systems. Attitude control of satellites has been tackled by the help of Self Organizing Fuzzy Logic Controllers (FLC), being a suitable candidate, as engineering experience is usually not available for a satellite system for matching performance through fixed fuzzy rules. Such type of controllers are thus more robust than the fixed rule controllers but the outcome is not always optimum [3], [4]. An integrated feedback/feedforward control system is proposed by [5], for reducing the vibration of flexible structures for large-angle attitude manoeuvre of the spacecraft. Lyapunov based control integrated with the Nil-Mode-Exciting profiler and an extended Input Shaping technique is utilized to effectively improve the transient vibration of the modal response. Vibration suppression is a desirable feature; active vibration suppression for a two-link flexible manipulator is proposed by [6]. This scheme is composed of an input shaper assisted by piezo actuator for active suppression of residual vibrations. This scheme is, however not suitable for a satellite system in which installation of piezo actuators is not practically viable. Design method that is more systematic is always preferable, as by .
