A Monolithic Self-Sensing Precision Stage: Design, Modeling, Calibration, and Hysteresis Compensation

This paper presents the design, modeling, calibration, and hysteresis compensation of a self-sensing precision stage used for active vibration isolation. The stage prototype is monolithically fabricated from the spring steel by wire electrical discharge machining process. Aiming to achieve an extremely compact structure, we design and fabricate a self-sensing actuator called smart piezo stack which is capable of not only generating high-resolution displacement but also monitoring the dynamic characteristics of the proposed stage. By means of the finite-element analysis and experimental measurements, we reveal and quantitatively analyze the crosstalk phenomenon in the smart piezo stack. After calibrating the sensitivity of the smart piezo stack experimentally, the dynamics model of the proposed stage is established. Furthermore, a nonlinear autoregressive moving average with exogenous inputs model based on backpropagation neural network is proposed to design a nonlinear controller based on adaptive inverse control. The intelligence of the developed controller allows the hysteresis in the stage which results from the embedded smart piezo stack to be directly compensated for without dynamics modeling in advance. Experimental validation of the adaptive inverse controller is conducted and the results demonstrate the effectiveness of the proposed mechanism and the developed control system.