Quaternion-based Finite-time Sliding Mode Controller Design for Attitude Tracking of a Rigid Spacecraft during High-thrust Orbital Maneuver in the Presence of Disturbance Torques

In this paper, a quaternion-based finite-time sliding mode attitude controller is designed for a spacecraft performing high-thrust orbital maneuvers, with cold gas thrusters as its actuators. The proposed cont roller results are compared with those of a quaternion feedback controller developed for the linearized spacecraft dynamics, in terms of settling t ime, steady-state error, number of thruster firings and their fuel usage. It is then proved that the sliding mode cont rol has enough robustness against disturbances as well as a high accuracy in at titude t racking and also a low number of thruster firings. A 6 degree of freedom (DOF) total simulation, including spacecraft dynamics, guidance, navigation and cont rol systems is also designed and the sliding mode controller performance in a sample t ransfer from an eclipt ic orbit to a circular one is investigated. In order to solve the chattering problem caused mainly because of the discont inuity of sliding mode cont rol algorithm and mult iple switching on sliding surfaces, the sign funct ion in the control input is replaced with a hyperbolic tangent function. Being aware of the advantages of sliding mode control method, using this algorithm in orbital t ransfers seems to be innovat ive and efficient .