| This thesis presents the design, development, and control of multi-degree-of-freedom nanopositioning stage for applications in self-assembly-based nanomanufacturing of DNA patterns. High speed nanopositioning is needed in a variety of applications, such as nanomanufacture and construction. Particularly, nanopositioning developed in this work can be utilized to study the effect that inducing nano- to micro- scale oscillations in the DNA pattern self-assembly process has on the fabrication efficiency and quality. A system was designed to provide three degrees of freedom that provides both versatility and positioning precision to the study of the self-assembly process. Actual component manufacture was completed for two dimensional motions, with the third dimension designed for concept. Piezoelectric bimorph actuators were chosen for their low cost and high precision positioning to provide motion to the system. For the applications of the bimorph actuators in multi-dimensional positioning however, adverse effects, including the vibration dynamics and the nonlinear hysteresis behavior of the actuators, challenge the precision tracking of the desired trajectory. Moreover, incorporating multiple degrees of freedom inherits an undesirable cross-axis dynamics coupling effect between two or more directions of motion. In this project, two recently-developed iterative control techniques, the modeling-free inverse-based iterative control (MIIC) and the high-order difference modeling-free iterative control (HODMIIC) techniques were comparatively studied through experiments to tackle these critical issues. These two techniques were compared through their use in controlling one-dimensional non-coupled motion trajectories of a variety of amplitude and frequency conditions. The superior HODMIIC algorithm is then further proven through successful control of two-dimensional coupled motion trajectories across similar amplitude and frequencies. |
