Adaptive vibration control for flexible satellite with output constraint and unknown control direction

The focus of this study is the output constraint and unknown control direction problem in flexible satellites. The satellite investigated here is composed of two symmetrical flexible solar panels and a centrebody. The system is described as a distributed parameter system modelled as partial differential equations (PDEs) due to the elastic displacements it contains. Furthermore, to make the actuator more stable, barrier Lyapunov function (BLF) is used to realize the output constraint on the centrebody. A Nussbaum function is introduced to establish a control scheme that stabilizes the system with unknown control direction, where all the signals of the closed-loop system can be proved to be uniformly bounded. A radial basis function neural network is employed to approximate the uncertain disturbance acting on the centrebody. The proposed control laws are validated by a series of simulations.