Hu, Tiejun (2006-05). Design and control of a 6-Degree-of-Freedom levitated positioner with high precision. Doctoral Dissertation. Thesis uri icon


  • 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.

publication date

  • May 2006