Integrated attitude-orbit dynamics and control of spacecraft systems: State of the art and future trends

Spacecraft orbit and attitude determination and control (OADC) is described as the methodology of determining and controlling the motion and orientation (i.e., the state vector, ephemeris, or state) of an orbiting object such as a spacecraft relative to the Sun, the Earth, or the stars [1]. The motion and orientation of a space-craft are estimated by a set of equations with the state adjusted in response to a set of discrete sensor's data and subject to both random and systematic errors [2]. In the context of this article, the integrated orbit and attitude determination and control (IO-ADC) problem is generally described by introducing statistical estimation techniques of determining the state of a spacecraft as a function of time using the set of observations. The spacecraft is supposed to be influenced by a variety of external forces and torques, such as gravity, aerodynamic drag, solar radiation, third-body disturbances, and Earth tidal effects [3]. The complex description of these forces and torques results in a highly nonlinear set of dynamical equations. Since the OADC equations and observational data are inherently nonlinear, linearization technique is often performed in which linear estimation methods are used to resolve the OADC problem [4].