High speed nanometer positioning using a hybrid linear motor

With ever increasing demand for higher accuracy and productivity, high speed ultraprecision table positioning technology is urgently required. In order to achieve nanometer positioning accuracy and high speed feed drive of the table, it is effective to minimize error factors in the table system by using a linear motor in perfect noncontact condition. In such a linear motor-driven table system of a noncontact type, however, the force ripple of the motor directly influences the linear motion error of the table. In this study, a hybrid linear motor has been developed which has no force ripple. The proposed hybrid linear motor is constructed from a voice coil motor and a coarse driving mechanism, e.g., a wire drive, Furthermore, a hybrid linear motor-driven aerostatic table system has been developed and the performance of the table system has been evaluated.