Model identification, design and experimental demonstration of robust controller for nanopositioning stage under uncertainties in micromanufacturing

The role played by nano positioning stages in Micromanufacturing requires them to be robust to uncertain variations in loading conditions and trajectory generation. The author has previously worked on devising a method for model identification of a precise linear standing wave ultrasonic motor driven nano positioning stage of resolution 100nm. In this paper, the author stresses on designing robust controllers for the estimated models using the principles of internal model control and robust response time. These controllers show a marked improvement of approximately 80% better response from the factory setting controller in terms of rise time and settling time. Their robustness is demonstrated through repetitive experiments of loading and unloading in increments using weights in the range of 2 grams to 50 grams. The effects of changes in velocities from 100mm/s to 800mm/s are also exhibited. Under uncertainty the designed controller gives an effective response showing same level of overshoot as the positioning stage in recommended conditions and a change of 0.1 to 0.3 milliseconds in the rise and settling time. Model Identification and controller design has been achieved in MATLAB^®. Experimental demonstration of robustness is carried out using PILine^® M663 stage and PIMikroMove^® software.