Velocity and Body Rate Control of a Spacecraft Using Robust Passivity-Based Control

This paper considers the problem of asymptotic stabilizing of velocity and body rates of a spacecraft in the presence of uncertainties and external disturbances. One of the important methods in controller design for nonlinear systems; is designing based on the passivity concept. This concept which provides a useful tool for analysis of nonlinear systems has been also used for asymptotic stabilizing of nonlinear dynamical systems especially mechanical systems. The passivity-based control law is a static output feedback and has valuable features. Because of existence of uncertainties and external disturbances in the state-space of equations of physical systems; first the robust version of passivity-based control method, which is recently developed in literature, is given and the control law for nonlinear uncertain systems with affine structure is presented. Then, this approach is used in controller design for a spacecraft. Since, this paper considers only the stabilization of velocity and body rates, therefore the reduced-order model is extracted from the state-space equation of a spacecraft with six degree of freedom and then the robust control law is designed. Computer simulations show the efficiency of the proposed controller in robust asymptotic stabilizing of the velocity and body rate vectors of the spacecraft in the presence of uncertainties and external disturbances.