This paper presents some motion control issues that we are addressing in developing a control system for a multi-degree-of-freedom stage designed for nano-imprint-lithography. We describe the motion control software and hardware configuration, and model the coordinate transformation among the spaces of sensors, stage position, and actuators. A characteristic problem that is common to many electric motor driven stages including the one we are working on is the excess number of motors and coils to the stage's kinematic degrees of freedom render a redundant system. To reduce thermal deformation of the work space by the heat generated by the motors, this redundancy is exploited. In minimizing the total electric power of the motors for a given force vector command from the servo controller we derive an interesting result that are general to common systems. Two formulations, one without and one with additional constraint for geometrically symmetric thermal deformation, for total motor heat minimization are considered. We will also present our initial PID servo control experimental result and discuss work in progress to further eliminate the servo errors in the PID loop.
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