Hu, Tiejun (2006-05). Design and control of a 6-Degree-of-Freedom levitated positioner with high precision. Doctoral Dissertation.
This dissertation presents a high-precision positioner with a novel superimposed
concentrated-field permanent-magnet matrix. This extended-range multi-axis positioner can
generate all 6-DOF (degree-of-freedom) motions with only a single moving part. It is actuated
by three planar levitation motors, which are attached on the bottom of the moving part. Three
aerostatic bearings are used to provide the suspension force against the gravity for the system.
The dynamic model of the system is developed and analyzed. And several control techniques
including SISO (single input and single output) and MIMO (multi inputs and multi outputs)
controls are discussed in the dissertation. The positioner demonstrates a position resolution of 20
nm and position noise of 10 nm rms in x and y and 15 nm rms in z. The angular resolution
around the x-, y-, and z-axes is in sub-microradian order. The planar travel range is 160 mm ??
160 mm, and the maximum velocity achieved is 0.5 m/s at a 5-m/s2 acceleration, which can
enhance the throughput in precision manufacturing. Various experimental results are presented in
this dissertation to demonstrate the positioner??s capability of accurately tracking any planar
trajectories. Those experimental results verified the potential utility of this 6-DOF high-precision
positioner in precision manufacturing and factory automation.