Linear ADRC Application in Position Loop on the Nanshan 26‐m Radio Telescope

In this paper, the linear active disturbance rejection control (LADRC) research is applied to the antenna’s position system of the Nanshan 26‐m radio telescope (NSRT26). The electromechanical servo system, such as a radio telescope, usually employs a conventional integer‐order PID controller in its position loop to achieve set‐value tracking and rejection of load disturbances. Since the sensitivity of the derivative (D) term to the measurement noise and the saturation of the integral (I) term, the PID control often weakens the actions of the D and I, mainly manifesting as a proportional (P) control. LADRC obtains a better control performance than PID using an extended state observer (ESO) to overcome the sensitivity to measurement noise and model uncertainties and a prior‐derivative control structure to attenuate the overshoot during dynamic switching. The equivalent form of first‐order LADRC, e.g., a combination of a tracking‐error compensator of PI with a low‐pass filter (PI‐F) and a command‐feedforward compensator, also explains the insensitivity of the LADRC to measurement noise. Both simulational and experimental results show that the system using the PI‐F of the 1st‐order LADRC control is fast and nonovershoot, and its settling time is reduced by 50% compared to the existing traditional PID control, which is important for improving the radio telescope observation efficiency and gain/phase‐reference tracking. When measurement noise and disturbances occur, LADRC compensates for them, resulting in improved command response performance for the system.