Lyapunov-type nonlinear spacecraft attitude control

A nonlinear controller design was developed for a spacecraft attitude control system. The spacecraft dynamics equations, which are nonlinear and coupled, were developed as a function of external disturbances without assuming small angles and therefore, without ignoring the product items. A controller based on Lyapunov theory was developed to deal with the complex model. The approach overcomes the controller difficulty resulting from the gravity gradient, which guarantees the Lyapunov stability. The equilibrium position can be reached by choosing a suitable parameter. Since neither linearization nor decoupling was used to simplify the model, the control result is more precise. A simulated result illustrates the effectiveness of the controller.