Simultaneous Six-Degree-of-Freedom Control of a Single-Body Magnetic Microrobot

• Published in: IEEE robotics and automation letters Vol. 4; no. 2; pp. 508 - 514
• Main Authors: Giltinan, Joshua, Sitti, Metin
• Format: Journal Article
• Language: English
• Published: Piscataway IEEE 01-04-2019; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Anisotropy; Bioengineering; Degrees of freedom; Electronic devices; Magnetic domains; Magnetic fields; Magnetic hysteresis; Magnetism; Magnetization; Magnetometers; Micro/nano robots; Micromanipulation; Microrobots; motion control; Perpendicular magnetic anisotropy; Rigid structures; Saturation magnetization; Stability; Torque
• ISSN: 2377-3766; 2377-3766
• DOI: 10.1109/LRA.2019.2891080

As precise motion-controlled applications of mobile untethered devices emerge into real-world scenarios, full manipulator dexterity will be required. In rigid bodies without joints, one such requirement will be the ability to control all six-degrees-of-freedom (DOF). Magnetic fields and their spatial gradients are ideal for micromanipulation due to their long-range strong forces and torques, but the 6-DOF closed-loop control of such devices is a current challenge. Here we present a single-body microrobot that simultaneously demonstrates all 6-DOF. We accomplish this through the magnetic shape anisotropy of the microrobot design, yielding magnetization components, which are used to generate a torque about the 6 th DOF. We show that, under our design conditions, we can independently control the magnetic field as well as the magnetic force and torque. This allows for the open-loop control of the other rotational DOFs, assuming the microrobot net magnetization vector will align with the magnetic field. We also describe a method that enables posing the 6 th DOF without feedback. These methods will enable the development of mobile submillimeter magnetic structures capable of full 6-DOF control for bioengineering, lab-on-a-chip, and desktop micromanufacturing applications.