Magnetic micro-actuators and systems (MAGMAS)

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 magnets compatible with microsystem technologies, MAGMAS will have a promising future.

Design and Optimization Strategies for Muscle-Like Direct Drive Linear Permanent Magnet Motors

“…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].…”

“…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.…”

“…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.…”

Basic Problems in Self-Assembling Robots and a Case Study of Segregation on Tribolon Platform

“…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.…”

Optimization of the force and power consumption of a microfabricated magnetic actuator

“…Electromagnetic-based microactuators combine both high noncontact forces and large actuation strokes [1]. By using permanent magnets, high energy densities can be achieved.…”