System Identification and Control Design for a Tip Tilt Nanopositioning System

The nanopositioning stage is one of the essential
components in the application of nanotechnology and
nanoscience. Past research has focused on the control
design for the nanopositioning stages with translation
motion. However, this paper examines the system
identification and control design for a tip tilt
nanopositioning stage with an experimental case study based
on the Queensgate NPS-θγ-2M prototype
nanopositioning stage that has two degrees of freedom (DOF)
of tip tilting motion. The paper presents the multi-input
multi-output (MIMO) position model and compares two control
design methods for the tip tilt nanopositioning stage,
namely single input single output (SISO) integral control
and MIMO robust H-infinity control with loop shaping
design. The robust H-infinity control has the advantage of
increasing the response speed and improving the bandwidth
while considering the whole multivariable model in the
design scheme and maintaining the control robustness. The
experiment results demonstrate that the MIMO robust
H-infinity control has a better control performance in
terms of the response time and bandwidth, compared with the
classical SISO integral control.