Internal model control-based adaptive attitude tracking

The attitude of a spacecraft is its orientation in space. The orientation is with respect to a particular reference like the Earth and Sun [1]. The spacecraft is considered to be a rigid body whose attitude can be described by two sets of equations, namely, the kinematics equation, which relates the time derivatives of the orientation angles to the an- gular velocity vector and the dynamics equation, which describes the time evolution of the angular velocity vector [2, 3]. Various parameterizations of the attitude exist to represent the orientation angles. A comprehensive survey of attitude representations is given in [4]. The attitude control problem was first presented in the literature in [5]. A general procedure for the design and analysis of a three-axis, large-angle attitude control system was developed based on properties common to all attitude control systems. In [6], a general framework is prepared for the analysis of attitude tracking control of a rigid body using the non- singular unit quaternion representation. An adaptive tracking control scheme wherein the unknown spacecraft inertia matrix is compensated using linear parameterization is discussed in [7]. Reference [8] proposes an adaptive attitude tracking controller that identifies the inertia matrix via periodic command signals. Reference [9] discusses the adaptive attitude tracking control using synthesized velocity from attitude measurements by incorporating a velocity filter formulation.