Fixed-time attitude tracking control for spacecraft without unwinding.

Abstract This paper investigates the fixed-time attitude tracking control problem for rigid spacecraft based on rotation matrix. Two anti-unwinding control schemes are developed such that the desired attitude can be tracked with bounded convergence time regardless of the initial conditions. The first controller is established on basis of a novel sliding mode surface without considering the external disturbance. In addition, the explicit description of the settling time can be provided under this controller. By revising the sliding mode surface and utilizing an adaptive law, the fixed-time stability can still be achieved under the second controller even in the presence of external disturbance. Theoretical analysis and numerical simulations are presented to demonstrate the validity of the proposed controllers. Highlights • Two attitude tracking controllers are designed for spacecraft. • Rotation matrix is used to construct the controllers. • Controllers in this paper are fixed-time stable. • Adaptive law is applied to deal with the external disturbances. [ABSTRACT FROM AUTHOR]