Terminal Sliding Mode Control for Attitude Tracking of Spacecraft under Input Saturation

Abstract

This paper investigates two robust finite-time controllers for the attitude control of spacecraft based on rotation matrix. The first controller can compensate external disturbances with known bounds, whereas the second one can deal with both external disturbances and input saturation by using the hyperbolic tangent function and auxiliary system. Both controllers can avoid the singularity and converge to zero in finite time by using novel fast nonsingular terminal sliding mode control. Because the controllers are designed based on a rotation matrix that represents the set of attitudes both globally and uniquely, the system can overcome the drawbacks of unwinding. Numerical simulations are presented to demonstrate the effectiveness of the proposed control schemes.