We developed a model-based controller for 6-DOF micropositioning of a precision stage using H∞ norm. For the design, a state-space system of the mathematical model of the stage is derived. In developing the controller, weighting functions are effectively designed in consideration of upper bounds of the sensitivity of the control loop and control input. Step responses in open and closed loop control are provided to verify the micropositioning performance of the stage. By applying the developed controller we prove that the inverse of the weighting function forms the upper bound of the control loop. It is also found that the controller makes the same sensitivity shape with all the DOFs due to the use of H∞ norm. The developed controller is expected to be applied successfully for industrial use.
