Velocity Control with Gravity Compensation for Magnetic Helical Microswimmers

Mahoney, Arthur W.; Sarrazin, John Cody; Bamberg, Eberhard; Abbott, Jake J.

doi:10.1163/016918611x568620

Cited by 118 publications

(80 citation statements)

References 13 publications

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“…where B 0 is the magnetic flux density at the center of the Helmholtz coils, f is the rotational frequency and (ũ,ṽ) are the basis vectors of the plane orthogonal to the axis n. The 3D Helmholtz coils capable of generating uniform rotating magnetic field are widely used by many researchers to rotate helical propulsive swimming microrobots in 3D space [41,[45][46][47]. Moreover, with the modulation of the currents passing through the coils, the Helmholtz coil setup can generate various magnetic fields adapted for the motion control of different microrobots: for example, a square wave oscillating magnetic field for actuating a jellyfish-like swimming microrobot [48], an on/off magnetic field for the motion control of flexible metal nanowire motors [49] or for a magnetic mite (MagMite) [50] and a conical magnetic field to decrease the off-axis motion of helical microrobots [51].…”

Section: Electromagnetic Actuation Systemsmentioning

confidence: 99%

“…Then, Ghosh et al [37] achieved following a curved trajectory (e.g., "R@H") with their helical microrobots, which were navigated by a pre-programmed controller to actuate the magnetic field. Mahoney et al [41] demonstrated a "U-turn" trajectory in a horizontal plane with the gravity compensation of helical microrobots. Jeong et al [74] used a pair of Maxwell coils in the vertical direction to compensate the gravity of a drilling microrobot.…”

Section: Open-loop Controlmentioning

confidence: 99%

“…Researchers have used different magnetic actuation systems allowing differently-sized workspace and degrees of freedom (DoF). Various motion control methods have been applied, developing from open-loop control [36,37,40,41] to closed-loop point-to-point positioning control [35,42] or closed-loop path following [43]. The aim of this paper is to review the magnetic actuation systems and the motion control methods for microrobots.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Magnetic Actuation Based Motion Control for Microrobots: An Overview

et al. 2015

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Untethered, controllable, mobile microrobots have been proposed for numerous applications, ranging from micro-manipulation, in vitro tasks (e.g., operation of microscale biological substances) to in vivo applications (e.g., targeted drug delivery; brachytherapy; hyperthermia, etc.), due to their small-scale dimensions and accessibility to tiny and complex environments. Researchers have used different magnetic actuation systems allowing custom-designed workspace and multiple degrees of freedom (DoF) to actuate microrobots with various motion control methods from open-loop pre-programmed control to closed-loop path-following control. This article provides an overview of the magnetic actuation systems and the magnetic actuation-based control methods for microrobots. An overall benchmark on the magnetic actuation system and control method is also discussed according to the applications of microrobots.

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Section: Electromagnetic Actuation Systemsmentioning

confidence: 99%

Section: Open-loop Controlmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Magnetic Actuation Based Motion Control for Microrobots: An Overview

et al. 2015

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“…The steering was realized by the gradient direction which was different from magnetically actuated helical swimmers. Mahoney showed open-loop controlled swimming of a helical swimmer with an overall length of 5 mm, which enabled a "U-turn" trajectory in the vertical plane [19]. He proposed a method to calculate the inclination angle of the helical swimmer with the horizontal plane, so that the helical swimmer could generate a propulsion force in the upward direction to compensate its own gravity.…”

Section: Introductionmentioning

confidence: 99%

Characterization of three-dimensional steering for helical swimmers

Hwang²,

Andreff

et al. 2014

2014 IEEE International Conference on Robotics and Automation (ICRA)

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Abstract-Helical microswimmers capable of propulsion at low Reynolds numbers have been proposed for many applications. However, closed-loop controlled helical swimmers are still challenging because of the limits of optical tracking, and a lack of control parameters lying on the swimming characteristics of both linear propulsion and steering. Although the linear propulsion characteristics of helical swimmers were extensively studied, the steering characteristics have not yet been clearly shown. Helical microswimmers are efficient in propulsion, whereas their high surface-to-volume ratio limits the steering performances. In this paper, we characterized both the direction and inclination steering using a real-time visual tracking of orientation. The direction steering efficiency could be increased in terms of response time with a higher inclination angle both in floating conditions and on a sticky substrate. We thus developed a 3D steering strategy by combining direction and inclination steering to improve the steering performance. We further expect that the characterization of steering performance can contribute to defining the control parameters for future closed-loop control.

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“…Therefore, a three-dimensional position control system is needed to compensate for the weight of the microrobot. [3] However, fabrication and measurement errors introduce uncertainties into the weight and buoyancy force of a microrobot. The hydrodynamic drag force is another source of uncertainty in microrobot dynamics.…”

Section: Introductionmentioning

confidence: 99%

Electromagnetic Steering of a Magnetic Cylindrical Microrobot Using Optical Feedback Closed-Loop Control

Ghanbari

Chang

Nelson

et al. 2014

International Journal of Optomechatronics

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Control of small magnetic machines in viscous fluids may enable new medical applications of microrobots. Small-scale viscous environments lead to low Reynolds numbers, and although the flow is linear and steady, the magnetic actuation introduces a dynamic response that is nonlinear. We account for these nonlinearities, and the uncertainties in the dynamic and magnetic properties of the microrobot, by using time-delay estimation. The microrobot consists of a cylindrical magnet, 1 mm long and 500 lm in diameter, and is tracked using a visual feedback system. The microrobot was placed in silicone oil with a dynamic viscosity of 1 Pa.s, and followed step inputs with rise times of 0.45 s, 0.51 s, and 1.77 s, and overshoots of 37.5%, 33.3%, and 34.4% in the x, y, and z directions, respectively. In silicone oil with a viscosity of 3 Pa.s, the rise times were 1.04 s, 0.72 s, and 2.19 s, and the overshoots were 47.8%, 48.5%, and 86.8%. This demonstrates that closed-loop control of the magnetic microrobot was better in the less viscous fluid.

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Velocity Control with Gravity Compensation for Magnetic Helical Microswimmers

Cited by 118 publications

References 13 publications

Magnetic Actuation Based Motion Control for Microrobots: An Overview

Magnetic Actuation Based Motion Control for Microrobots: An Overview

Characterization of three-dimensional steering for helical swimmers

Electromagnetic Steering of a Magnetic Cylindrical Microrobot Using Optical Feedback Closed-Loop Control

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