Conference Paper

OctoMag: An Electromagnetic System for 5-DOF Wireless Micromanipulation

Inst. of Robot. & Intell. Syst., ETH Zurich, Zurich, Switzerland
DOI: 10.1109/ROBOT.2010.5509857 Conference: IEEE International Conference on Robotics and Automation, ICRA 2010, Anchorage, Alaska, USA, 3-7 May 2010
Source: DBLP

ABSTRACT We demonstrate five-degree-of-freedom (5-DOF) wireless magnetic control of a fully untethered microrobot with a magnetic steering system we call OctoMag. Although only occupying a single hemisphere, this system is capable of isotropically applying forces on the order of 1-40 μN with unrestricted control of the 2 orienting DOF. These capabilities are enabled through the use of soft-magnetic-cores which provide an increase of approximately 20× that of air cores in magnetic-field strength, but comes at the cost of more complicated interactions between coils. We propose a modeling mechanism that assumes the field contributions of the individual currents superimpose linearly when using cores with large linear regions and negligible hysteresis. When designing the system, the locations and quantity of electromagnets were optimized with regards to the force generation in the worst-case direction predicted by the model. The resultant system is capable of both open and closed-loop operation over a workspace of 4 cm3. OctoMag was primarily designed for the control of intraocular microrobots for delicate retinal procedures, but also has potential uses in other medical applications or micromanipulation under an optical microscope.

Full-text

Available from: Brad Nelson, Jun 02, 2015
1 Follower
 · 
242 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Recently, the locomotion of a microrobot wirelessly actuated by electromagnetic actuation systems has been studied in many ways. Because of the inherent characteristics of an electromagnetic field, however, the magnetic field of each coil in the electromagnetic actuation system induces magnetic field interferences, which can distort the desired electromagnetic field, preventing the microrobot from following the desired path. In this article, we used two pairs of Helmholtz coils and two pairs of Maxwell coils in a two-dimensional electromagnetic actuation system. Generally, the two pairs of Helmholtz coils generate the torque for the rotation of the microrobot and the two pairs of Maxwell coils generate the propulsion force of the microrobot. Both pairs of Helmholtz and Maxwell coils have to work to simultaneously align and propel the microrobot in a desired direction. In this situation, however, the electromagnetic fields produced by the Helmholtz coils can interfere with those produced by the Maxwell coils. This interference is closely dependent on the position of the microrobot in the region of interest inside the electromagnetic coils system. This means that the alignment direction and propulsion force of the microrobot can be distorted according to the position of the microrobot. Therefore, we propose a compensation algorithm for the electromagnetic field interference using the position information of the microrobot to correct the magnetic field interferences. First, the interference of an electromagnetic field obeying the Biot–Savart law is analyzed by numerical analysis. Second, a position-based compensation algorithm for the locomotion of a microrobot is proposed. Various locomotion tests of a microrobot verified that the proposed compensation algorithm could reduce the normalized average tracking error from 5.25% to 1.92%.
    ARCHIVE Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science 1989-1996 (vols 203-210) 10/2013; 227(9):1915~1926. DOI:10.1177/0954406212466349 · 0.59 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Microactuators are an important tool for precise manipulation of components and materials in nanotechnologies. The problems of design and application of microactuators for micro- and nanopositioning, microassembly, and microrobotics are considered in this paper. The basic parameters and models of piezoelectric, magnetostriction, electromagnetic, electrostatic, electrothermal, and hybrid microactuators are described. A general information approach that implies the description of physical models used in order to analyze microactuator behavior and optimize their design is considered.
    Automatic Documentation and Mathematical Linguistics 12/2011; 45(6). DOI:10.3103/S0005105511060069
  • [Show abstract] [Hide abstract]
    ABSTRACT: Nanosciences have recently proposed a lot of proofs of concept of innovative nanocomponents and especially nanosensors. Going from the current proofs of concept on this scale to reliable industrial systems requires the emergence of a new generation of manufacturing methods able to move, position and sort micro-nano-components. We propose to develop 'No Weight Robots-NWR' that use non-contact transmission of movement (e.g. dielectrophoresis, magnetophoresis) to manipulate micro-nano-objects which could enable simultaneous high throughput and high precision. This article deals with a control methods which enables to follow a high speed trajectory based on visual servoing. The non-linear direct model of the NWR is introduced and the calculation of the inverted model is described. This inverted model is used in the control law to determine the control parameter in function of the reference trajectory. The method proposed has been validated on an experimental setup whose time calculation has been optimized to reach a control period of 1 ms. Future works will be done on the study of smaller components e.g. nanowires, in order to provide high speed and reliable assembly methods for nanosystems.
    Robotics and Automation (ICRA), 2013 IEEE International Conference on; 01/2013