Comparison of LQG and ADRC based wind disturbance rejection schemes for Deep Space Antenna

This paper deals with the comparison of wind disturbance rejection schemes for a large diameter deep space antenna. Classical controllers (P, PI, PID) have been widely used to control such antennas due to their ease of implementation. However, in the presence of external disturbances like wind, the tracking accuracy of classical controllers deteriorates. To enhance the tracking accuracy, this paper presents two advanced control schemes, namely linear quadratic gaussian (LQG) and active disturbance rejection control (ADRC) to estimate and compensate the wind disturbance. The ADRC considers the system states and wind disturbance as a lumped disturbance and designs a reduced order linear extended state observer (LESO) to estimate the lumped disturbance. This estimated disturbance is compensated by designing a proportional controller. The LQG control scheme is based on optimal control philosophy, which has a linear quadratic regulator (LQR) to minimize the tracking error and control effort, along with a Kalman filter which estimates the states in the presence of wind disturbances. The wind disturbances are modelled as sinusoidal, and they act as load torques to the antenna. Simulation results comparing the two modern control schemes with classical control is presented in this paper. It is evident from the simulations that the ADRC has better accuracy compared to LQG and classical controller.