Design and control of a 6-Degree-of-Freedom levitated positioner with high precision

Abstract

This dissertation presents a high-precision positioner with a novel superimposed\nconcentrated-field permanent-magnet matrix. This extended-range multi-axis positioner can\ngenerate all 6-DOF (degree-of-freedom) motions with only a single moving part. It is actuated\nby three planar levitation motors, which are attached on the bottom of the moving part. Three\naerostatic bearings are used to provide the suspension force against the gravity for the system.\nThe dynamic model of the system is developed and analyzed. And several control techniques\nincluding SISO (single input and single output) and MIMO (multi inputs and multi outputs)\ncontrols are discussed in the dissertation. The positioner demonstrates a position resolution of 20\nnm and position noise of 10 nm rms in x and y and 15 nm rms in z. The angular resolution\naround the x-, y-, and z-axes is in sub-microradian order. The planar travel range is 160 mm ??\n160 mm, and the maximum velocity achieved is 0.5 m/s at a 5-m/s2 acceleration, which can\nenhance the throughput in precision manufacturing. Various experimental results are presented in\nthis dissertation to demonstrate the positioner??s capability of accurately tracking any planar\ntrajectories. Those experimental results verified the potential utility of this 6-DOF high-precision\npositioner in precision manufacturing and factory automation.