Development of nanopositioning mechanism with real-time compensation algorithm to improve the positional accuracy of a linear stage

A compensation mechanism with six degrees of freedom (DOF) was developed to enable precise control of a linear stage. Geometric, thermally induced, and dynamic errors in the linear stage were compensated for in real time by the nanopositioning stage. A stage-based hinge with high structural stiffness and rapid response characteristics was modified for parallel operation. The stage's full range of motion was measured and kinematics was used to calculate the displacement required by each actuator to compensate for the errors. Except for the displacement error of the linear stage, the contribution of each error source was measured by a reference mirror and five capacitive sensors. A compensation algorithm, based on a recursive method, was used to improve the positioning accuracy of the system. The performance of the stage presented here was investigated by measuring, and compensating for, the five-DOF linear stage errors in real time. In practice, the peak-to-valley errors of the translational and rotational errors were reduced by 89% and 93%, respectively.