Quantized attitude control of rigid spacecraft without unwinding

Advanced spacecrafts like fractionated spacecrafts are developed using independent modules that interact with each other through a wireless communication channel. The designing of an attitude controller of such spacecrafts requires to abide by the constraints on communication resources. Therefore, in this paper, a logarithmic quantizer is employed for the attitude regulation of rigid spacecraft under limited utilization of the wireless network. The given spacecraft has inertial uncertainties and external disturbances. Furthermore, the quaternion based kinematics attitude representation suffers from the problem of unwinding due to multiple equilibrium points. Thus, under the action of the proposed anti-unwinding controller, the closed-loop system states converge to the uniformly ultimate bounds while attenuating the lumped disturbances and avoiding the unwinding phenomenon. The simulation analysis and the comparative study with multiple initial conditions illustrate the superior performance of the proposed control technique.