Robotics: Science and Systems X

Six-Degrees-of-Freedom Remote Actuation of Magnetic Microrobots

Eric Diller, Joshua Giltinan, Guo Zhan Lum, Zhou Ye, Metin Sitti


Existing remotely-actuated microrobots powered by magnetic coils far from the workspace exhibit a maximum of only five-degrees-of-freedom (DOF) actuation, as a driving torque about the magnetization axis is not achievable. This lack of orientation control limit the effectiveness of existing microrobots for precision tasks of object manipulation and orientation for advanced medical, biological and micro-manufacturing applications. This paper presents a novel magnetic actuation method that allows these robots to achieve full six-DOF actuation by allowing for a non-uniform magnetization profile within the microrobot body. This non-uniform magnetization results in additional rigid-body torques to be induced from magnetic forces via a moment arm. A general analytical model presents the working principle for continuous and discrete magnetization profiles. Using this model, microrobot design guidelines are introduced which guarantee six-DOF actuation capability. Several discrete magnetization designs which possess reduced coupling between magnetic forces and induced rigid-body torques are also presented. A simple permanent-magnet decoupled prototype is fabricated and used to quantitatively demonstrate the accuracy of the analytical model in a constrained-DOF environment and qualitatively for free motion in a viscous liquid three-dimensional environment. Results show that desired forces and torques can be created with high precision and limited parasitic actuation, allowing for full six-DOF actuation using limited feedback control.



    AUTHOR    = {Eric Diller AND Joshua Giltinan AND Guo Zhan Lum AND Zhou Ye AND Metin Sitti}, 
    TITLE     = {Six-Degrees-of-Freedom Remote Actuation of Magnetic Microrobots}, 
    BOOKTITLE = {Proceedings of Robotics: Science and Systems}, 
    YEAR      = {2014}, 
    ADDRESS   = {Berkeley, USA}, 
    MONTH     = {July},
    DOI       = {10.15607/RSS.2014.X.013}