Active vibration and maneuver control of a flexible spacecraft using robust and non-singular fast terminal sliding mode algorithms

This paper deals with a robust active vibration and non-singular fast terminal sliding mode control design for flexible spacecraft attitude maneuvers. First, the fully coupled nonlinear rigid-flexible dynamic model of the spacecraft in the three-axis maneuver is derived using Lagrange's equations in terms of quasi-coordinates. Then, the attitude control law is designed based on a fast non-singular terminal sliding surface, which leads to the zero convergence of attitude tracking and angular velocity errors in a finite time in the presence of external disturbances and parameter uncertainties. Next, the flexible panels' residual vibrations during and after the maneuver have been reduced exponentially using a robust active vibration control algorithm through piezoelectric sensor/actuator patches. It has been proven that this algorithm ensures the stability of the closed loop system and eliminates the need for conservative assumptions regarding uncertainties and external disturbances at the upper limit. The finite-time convergence of the closed-loop system with a hybrid control approach is proved by the Lyapunov stability theory. The numerical simulations using 4th order Runge-Kutta approach show the simultaneous utilization of the proposed attitude and vibration controllers' performance compared to the classical approaches for dynamical systems with structural flexibility.