A Measurement Noise Rejection Method in the Feedback Control System Based on Noise Observer

In the conventional feedback control system, the control accuracy is affected by the measurement noise. In this article, a novel method is proposed for the purpose of the measurement noise rejection in the single-input single-output (SISO) feedback control system. By adding an inner noise observer loop in the conventional feedback loop, we apply the "observer-based" control method into the sensor output signal processing. The proposed method is capable of reducing the measurement noise in frequencies overlapping with the control bandwidth without affecting the tracking ability of the feedback control system. Moreover, this method is simple in that its noise suppression ability is merely decided by the Q-filter, which can be set as a constant. In addition, a necessary and sufficient condition for the system stability is presented considering the uncertainties of the real plant. It is shown that when the Q-filter is zero, the uncertainties of the plant cannot influence the stability of the system. To verify the effectiveness, both the tracking performance and noise rejection performance of the proposed method is simulated, comparing with the conventional feedback control system. Finally, laboratory experiment is conducted with a tracking mirror control system.