Dynamics and variable structure control of a spacecraft with elastic appendages

In order to study the dynamics, the attitude stabilization control and the suppression of appendage vibration for a kind of elastic spacecraft, accurate dynamical equations were established by the Lagrangian approach using quasi-coordinates for a spacecraft which contained a rigid platform and a given number of elastic appendages, and a feedback control law was then designed using variable structure control method based on nonlinear and low mode dynamical models. The numerical simulation results showed that the attitude of the spacecraft and the vibration of the appendage were both under effective control by the control law, the dynamical equations of such a system were nonlinear differential equations with time-varying coefficients, and the low mode vibration of the appendages had a significant effect on the attitude motion of the platform. The variable structure controller based on a nonlinear and low mode model performs well for such a system.