A Modified Active Disturbance Rejection Control Strategy for DC Servo System with External Disturbance and Measurement Noise

This article presents a modified active disturbance rejection control (MADRC) strategy to improve the disturbance rejection and noise attenuation performance for direct-current (DC) servo system with external disturbance and measurement noise. Firstly, a tracking differentiator (TD) with a simple structure is devised to provide the smooth tracking signal and its derivative. Secondly, a fal filter is designed to reduce the level of noise included in the sensor signal. Thirdly, a novel cascade extended state observer (ESO) including two ESOs is constructed to estimate the total disturbance of the system. The disturbance suppression performance is analyzed via frequency domain method and the stability criterion is developed based on input to state stability (ISS) framework. Finally, simulations are conducted to reveal the superiorities of MADRC in anti-disturbance ability and noise rejection capability compared with ADRC.