Fixed-time attitude tracking control for spacecraft with input quantization

This paper investigates the fixed-time attitude tracking control problem for rigid spacecraft with input quantization and external disturbances. A novel fixed-time disturbance observer is designed to estimate unknown disturbances. By using adding a power integrator technique, a fixed-time controller is constructed, which can guarantee system states converge to a neighborhood of origin in fixed time. The parameter of quantizer can be coarsely chosen. Finally, simulation results are employed to demonstrate the effectiveness of the developed control scheme.