Abstract:Magnetic interactions provide outstanding performances for powerful integrated micro-actuators. This paper explains how magnetic interactions involving permanent magnets, currents, and various magnetic materials remain very effective and even improve as dimensions are reduced. The technological problems that have slowed the development of magnetic micro-actuators and systems (MAGMAS) are progressively being solved. As long as materials scientists continue to develop better thick-film patterned permanent magnet… Show more
“…This relationship suggests that it should be possible to achieve an arbitrarily high force density so long as the pole pitch is made sufficiently small. While this is contrary to standard motor design practice, which is done by simply assuming a maximum current density (typically 10 7 A/m 2 ), it is in agreement with the scaling described by Cugat et al [7] and can be intuitively explained with reference to microelectronics, where current densities over 10 9 A/m 2 are routinely used in small bond wires and interconnects. As a numerical example consider once again the work loop parameters associated with pigeon flight muscles [9], which produce an RMS force densityF ≈ 700 N/kg, the optimum geometry for the HG configuration, a coil thermal conductivity of κ c ≈ 1 W/m · K, and a maximum temperature rise of 100 • C. If we wish to have a pole pitch of greater than 10 mm, we will require a heat transfer coefficienth ≥ 400 W/m 2 K. This heat transfer coefficient can be achieved through vigorous air cooling or by simple liquid cooling [21].…”
Section: Thermal Modelsupporting
confidence: 81%
“…In particular, the simplicity of direct-drive EM actuators is appealing as a canvas for improvements, and we will specifically discuss linear permanentmagnet (PM) direct drive actuators. Permanent magnet motors have favorable scaling properties [7], as do direct-drive linear actuators. While direct-drive motors are generally known for having low force densities and low efficiencies [2], their performance envelope is determined by their electromagnetic and thermal design, which can be modeled from basic physics, rather than by the tribological properties of gears, which are both difficult to model and difficult to improve.…”
Section: Introductionmentioning
confidence: 99%
“…At present, general models for the maximum theoretical performance of linear PM motors in terms of fundamental physics are unavailable [7], [8]; our objective will therefore be to develop such a general model, and to use it to find ways to improve the force capability and efficiency of these motors to a level competitive with biological muscle. Using our model, we will establish that direct-drive linear PM motors can be constructed with power densities, force densities, and efficiencies all simultaneously exceeding those of biological muscle.…”
Abstract-We report a new approach to the design of directdrive linear permanent magnet motors for use in general-purpose robotic actuation, with particular attention to applications in bird-scale flapping-wing robots. We show a simple, quantitative analytical modeling framework for this class of actuators, and demonstrate inherent scaling properties that allow the production of motors with force densities and efficiencies comparable to those of biological muscles. We will show how this model leads to a set of practical design specifications for muscle-like motors, and examine the resulting trade-off between thermal management and motor fabrication complexity.
“…This relationship suggests that it should be possible to achieve an arbitrarily high force density so long as the pole pitch is made sufficiently small. While this is contrary to standard motor design practice, which is done by simply assuming a maximum current density (typically 10 7 A/m 2 ), it is in agreement with the scaling described by Cugat et al [7] and can be intuitively explained with reference to microelectronics, where current densities over 10 9 A/m 2 are routinely used in small bond wires and interconnects. As a numerical example consider once again the work loop parameters associated with pigeon flight muscles [9], which produce an RMS force densityF ≈ 700 N/kg, the optimum geometry for the HG configuration, a coil thermal conductivity of κ c ≈ 1 W/m · K, and a maximum temperature rise of 100 • C. If we wish to have a pole pitch of greater than 10 mm, we will require a heat transfer coefficienth ≥ 400 W/m 2 K. This heat transfer coefficient can be achieved through vigorous air cooling or by simple liquid cooling [21].…”
Section: Thermal Modelsupporting
confidence: 81%
“…In particular, the simplicity of direct-drive EM actuators is appealing as a canvas for improvements, and we will specifically discuss linear permanentmagnet (PM) direct drive actuators. Permanent magnet motors have favorable scaling properties [7], as do direct-drive linear actuators. While direct-drive motors are generally known for having low force densities and low efficiencies [2], their performance envelope is determined by their electromagnetic and thermal design, which can be modeled from basic physics, rather than by the tribological properties of gears, which are both difficult to model and difficult to improve.…”
Section: Introductionmentioning
confidence: 99%
“…At present, general models for the maximum theoretical performance of linear PM motors in terms of fundamental physics are unavailable [7], [8]; our objective will therefore be to develop such a general model, and to use it to find ways to improve the force capability and efficiency of these motors to a level competitive with biological muscle. Using our model, we will establish that direct-drive linear PM motors can be constructed with power densities, force densities, and efficiencies all simultaneously exceeding those of biological muscle.…”
Abstract-We report a new approach to the design of directdrive linear permanent magnet motors for use in general-purpose robotic actuation, with particular attention to applications in bird-scale flapping-wing robots. We show a simple, quantitative analytical modeling framework for this class of actuators, and demonstrate inherent scaling properties that allow the production of motors with force densities and efficiencies comparable to those of biological muscles. We will show how this model leads to a set of practical design specifications for muscle-like motors, and examine the resulting trade-off between thermal management and motor fabrication complexity.
“…The scalability of physical interaction mechanisms -especially electrostatic and magnetic -are well examined in [11,1]. Here we briefly describe the basics of these two physical quantities.…”
Abstract. It has been a quite while since people realized that self-assembly technique may be a strong method to manufacture 3D micro products. In this contribution, we investigate some major concerns about realizing such a small sized robot. First we introduce the concept of self-assembly and introduce examples both from nature and artificial products. Followed by the main problems in self-assembly which can be seen in various scales, we classify them into four groups -(A) assembly constraint issues, (B) stochastic motion issues, (C) interactions on physical property issues, and (D) engineering issues. Then we show a segregation effect with our developed platform as an example of self-organizing behavior achieved in a distributed manner.
“…Electromagnetic-based microactuators combine both high noncontact forces and large actuation strokes [1]. By using permanent magnets, high energy densities can be achieved.…”
a b s t r a c tThe force (F) and the power consumption (P) of a magnetic actuator are modeled, measured and optimized in the context of developing micro-actuators for large arrays, such as in portable tactile displays for the visually impaired. We present a novel analytical approach complemented with finite element simulation (FEM) and experiment validation, showing that the optimization process can be performed considering a single figure of merit F/ √ P. The magnetic actuator is a disc-shaped permanent magnet displaced by planar microcoil. Numerous design parameters are evaluated, including the width and separation of the coil traces, the trace thickness, number of turns and the maximum and minimum radius of the coil. We obtained experimental values of F/ √ P ranging from 2 to 12 mN/ √ W using up to 2-layer coils of both microfabricated and commercial printed circuit board (PCB) technologies. This performance can be further improved by a factor of two by adopting a 6-layer technology. The method can be applied to a wide range of electromagnetic actuators.
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