Fixed-Time Inverse Optimal Attitude Tracking Control for Rigid Spacecraft

Fixed-time attitude tracking control problem is addressed in this paper for spacecraft with parameter uncertainty and external disturbance. To compensate for the influence of the lumped disturbance consisting of parameter uncertainty and external disturbance, an extended state observer is applied. Based on the inverse optimal control approach, a traditional control Lyapunov function controller is introduced, which guarantees the globally asymptotical stability of the nominal spacecraft system. Then, in order to ensure the practically fixed-time stability of the whole control system, a fixed-time integral sliding mode controller based on control Lyapunov function is employed. Simulation results show the effectiveness of the proposed controller.