This dissertation presents two novel 6-axis magnetic-levitation (maglev) stages that are capable of nanoscale positioning. These stages have very simple and compact structure that is advantageous to meet requirements in the next-generation nanomanufacturing. The 6-axis motion generation is accomplished by the minimum number of actuators and sensors. The first-generation maglev stage is capable of generating translation of 300 ??m in x, y and z, and rotation of 3 mrad about the three orthogonal axes. The stage demonstrates position resolution better than 5 nm rms and position noise less than 2 nm rms. It has a light moving-part mass of 0.2126 kg. The total power consumption by all the actuators is only around a watt. Experimental results show that the stage can carry, orient, and precisely position an additional payload as heavy as 0.3 kg. The second-generation maglev stage is capable of positioning at the resolution of a few nanometers over a planar travel range of several millimeters. A novel actuation scheme was developed for the compact design of this stage that enables 6-axis force generation with just 3permanent-magnet pieces. Electromagnetic forces were calculated and experimentally verified. The complete design and construction of the second-generation maglev stage was performed. All the mechanical part and assembly fixtures were designed and fabricated at the mechanical engineering machine shop. The single moving part is modeled as a pure mass due to the negligible effect of the magnetic spring and damping. Classical as well as advanced controllers were designed and implemented for closed-loop feedback control. A nonlinear model of the force was developed and applied to cancel the nonlinearity of the actuators over the large travel range. Various experiments were conducted to test positioning, loading, and vibration-isolation capabilities. This maglev stage has a moving-part mass of 0.267 kg. Its position resolution is 4 nm over a travel range of 5 ?? 5 mm in the x-y plane. Its actuators are designed to carry and precisely position an additional payload of 2 kg. Its potential applications include semiconductor manufacturing, micro-fabrication and assembly, nanoscale profiling, and nano-indentation.

Input shaping and Proportional-Integral-Derivative (PID) feedback control are simple, easy-to-implement and generally low cost control strategies. Considering this, it is remarkable that they are also very effective control techniques. In fact, a majority of the world's feedback controllers utilize PID (or the subset PD) control. In addition, input shaping has seen significant use on real-world machines such as cranes, micro-mills, coordinate measuring machines, computer disc drive manufacturing machines, spacecraft, etc. However, despite similarities in effectiveness and ease of implementation, input shaping and PID feedback control are fundamentally different strategies. Input shaping is an anticipatory control scheme capable of enabling quick, low-vibration motions. PID feedback control is reactive in nature, and it is primarily required to deal with problems such as modeling errors, disturbances and nonlinearities. Of course, PID control is also used to reduce vibrations (as in the case of input shaping). But, because it is a reactive controller, it is slower than input shaping at eliminating motion-induced vibration. Given their effectiveness and practicality, as well as the fact that they address important and complimentary control issues, it would be advantageous to combine these two control strategies. The result would still be practical and effective, yet would now address a range of system phenomenon beyond that which is capable by either of the individual control techniques. However, there is a definite gap in the state-of-the-art technology for combining these techniques. For example, little research has addressed the intelligent combination of traditional, outside-the-loop input shaping and PID feedback control. In addition, only a few researchers have attempted to place input shaping filters within feedback loops. This research studies the intelligent combination of input shaping and PID feedback control by developing a concurrent design procedure for outside-the-loop input shaping/PID feedback combinations and by analyzing the effect of placing input shaping filters within feedback loops.

This dissertation presents two novel 6-axis magnetic-levitation (maglev) stages that are capable of nanoscale positioning. These stages have very simple and compact structure that is advantageous to meet requirements in the next-generation nanomanufacturing. The 6-axis motion generation is accomplished by the minimum number of actuators and sensors. The first-generation maglev stage is capable of generating translation of 300 ??m in x, y and z, and rotation of 3 mrad about the three orthogonal axes. The stage demonstrates position resolution better than 5 nm rms and position noise less than 2 nm rms. It has a light moving-part mass of 0.2126 kg. The total power consumption by all the actuators is only around a watt. Experimental results show that the stage can carry, orient, and precisely position an additional payload as heavy as 0.3 kg. The second-generation maglev stage is capable of positioning at the resolution of a few nanometers over a planar travel range of several millimeters. A novel actuation scheme was developed for the compact design of this stage that enables 6-axis force generation with just 3permanent-magnet pieces. Electromagnetic forces were calculated and experimentally verified. The complete design and construction of the second-generation maglev stage was performed. All the mechanical part and assembly fixtures were designed and fabricated at the mechanical engineering machine shop. The single moving part is modeled as a pure mass due to the negligible effect of the magnetic spring and damping. Classical as well as advanced controllers were designed and implemented for closed-loop feedback control. A nonlinear model of the force was developed and applied to cancel the nonlinearity of the actuators over the large travel range. Various experiments were conducted to test positioning, loading, and vibration-isolation capabilities. This maglev stage has a moving-part mass of 0.267 kg. Its position resolution is 4 nm over a travel range of 5 ?? 5 mm in the x-y plane. Its actuators are designed to carry and precisely position an additional payload of 2 kg. Its potential applications include semiconductor manufacturing, micro-fabrication and assembly, nanoscale profiling, and nano-indentation.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 174-179). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (p. 198-207).

Thesis (M. Sc.)--University of Hong Kong, 1967. / Mimeographed.

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