Robust Attitude Tracking Control for Spacecraft with Quantized Torques

The problem of spacecraft attitude tracking with limited communication to actuators is addressed in this paper. A hysteresis quantizer is employed to quantize the signal of control torque. The hysteresis quantizer requires low communication rate and avoids control chattering. An indirect (nonregressor-based) robust adaptive control scheme is proposed to deal with the effects of quantization error and external disturbances. The proposed control scheme together with the quantizer ensures global boundedness of all the signals in the closed-loop system and enables the attitude tracking error to converge toward a residual.