Design and fabrication of a maglev linear actuator capable of nanopositioning

Abstract

This thesis presents the design and fabrication of a novel magnetically levitated (maglev) linear actuator. The linear actuator has a linear positioning range of ł250 mm. It will act as a unit actuator in a six-degrees-of-freedom (6-DOF) maglev instrument. The applications of this generic 6-DOF instrument are manufacturing of nanoscale structures, assembly of microparts, vibration isolation of delicate instrumentation, and telerobotics. The underlying electromechanical design and analysis, theoretical and experimental actuation forces determination, stochastic noise/disturbance modeling and close-loop control results for the linear actuator are described in this thesis. The linear actuator generates an axial force of 2.3 N at a current of 2 A with the size of the magnets and the coils determined by the electromagnetic analysis. Three of these actuators in the 6-DOF maglev instrument will have sufficient force capacity to levitate and accelerate the moving part mass of 0.22 Kg. We also characterized the noise and disturbance using stochastic noise/disturbance modeling. This characterization helps in accounting for the sources of noise/disturbance in the single- and 6-DOF instruments. The closed-loop control is applied with the feedback from the capacitive position sensor. Closed-loop control bandwidth of the system is 57 Hz. The actuator achieves a 6[] positioning noise of 17.76 nm. This design of the linear actuator can be readily scaled to accommodate various positioning ranges and force requirements.