Date of Award
Master of Science
Electrical and Computer Engineering
Magnetic manipulators are a class of systems for noncontact control of magnetized objects at a distance. These systems have found a range of applications in minimally invasive medical procedures, microrobotics, magnetic tweezers, microfluidics, and lab-on-a-chip devices. The magnetic field used for manipulation is conventionally produced by arrays of electromagnets, which are simply controlled by their voltages. However, electromagnets suffer from the disadvantage of generating much weaker magnetic fields compared to the permanent magnets of similar size, weight, and cost. Therefore, research efforts are ongoing to replace electromagnets with permanent magnets in order to develop more compact and less expensive magnetic manipulators. In these manipulators, magnetic field is controlled by displacement of the permanent magnets using mechanical actuators.This thesis intends to replace electromagnets with permanent magnets in the magnetic levitation systems (MLS). An MLS is a one-dimensional (1D) magnetic manipulator that levitates magnetic objects against gravity by feedback control of magnetic force applied to them. Instead of controlling the magnetic force of electromagnets using their voltages, in this work, the magnetic force is controlled by a linear servomotor which adjusts the distance between a permanent magnet and the levitating object. Based on this concept, a permanent magnet MLS is designed, implemented, and stabilized by feedback control, levitating a ferromagnetic sphere of diameter 5 mm at an equilibrium point i.e. 3 mm above its initial position. The resulting MLS is tested in practice and its performance is verified by experiments.The MLS developed in this work features many properties of more complex 2D and 3D magnetic manipulators. Therefore, it provides a convenient means for early study of more complex magnetic manipulators. In particular, it can be used to empirically study the linear limitation of small bandwidth and nonlinear limitation of finite slew rate of the mechanical actuators on the overall performance, including the stability, of magnetic manipulators.
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