Robust output feedback control for saturated linear systems with magnitude and rate constraints

The paper investigates a robust controller design approach that can independently addresses both the magnitude and rate constraints on actuator dynamics. With the augmentation of integral dynamics to the systems actuator, the original control effort is formulated as new states in the augmented dynamics formulation and the inputs of the integrator present the rate of the control efforts. The feedback gain is then designed to obtain suitable actuator dynamics such that the desired H^∞ performance can be optimized and the magnitude the rate constraints can be satisfied. The proposed robust output feedback control law is constructed in terms of linear matrix inequalities. A suitable chosen initial state condition, which represents the desired set of tracking commands, is treated as a design parameter for controller construction algorithm. By the example of satellite attitude control, the effectiveness of the proposed algorithm is verified through the achievable H^∞ performance with different specified constraints on the magnitude and rate of the control torque.