Damping and tracking control of nanopositioning stages with double delayed position feedback

This paper presents a new damping control scheme for piezoelectric nanopositioning stages with double delayed position feedback (DDPF). The DDPF in the inner loop is proposed to suppress vibration of the nanopositioning stage, which leads to a double time-delay system. A new numerical differential method is proposed to determine the parameters of the DDPF with pole placement. Then, a high-gain proportional-integral (PI) controller is designed in the outer loop to achieve a low level of tracking errors, which includes the hysteresis nonlinearity, disturbance, and modeling uncertainties. Experimental tests with various control schemes are conducted on a piezoelectric nanopositioning stage to verify the effectiveness of the proposed method. Experimental results reveal that the control bandwidth of the system is improved from 79 Hz (with the PI controller), 416 Hz (with the conventional delayed position feedback based controller), and 422 Hz (with the recursive delayed position feedback based controller) to 483 Hz (with the proposed controller).