Adaptive Finite-Time Control for Attitude Tracking of Spacecraft under Input Saturation

This paper investigates two robust finite-time controllers for the attitude control of the spacecraft by using a modified terminal sliding mode surface. With the use of terminal sliding mode control and adaptive control, the controllers under input saturation can compensate both external disturbances and the uncertainty of the model parameters. By using the first and the second controller, the closed-loop system is finite-time stability and practical finite-time stability, respectively. As the system model is based on the rotation matrix, both controllers are without unwinding. Numerical simulations are given to demonstrate the effectiveness of the finite-time controllers.