Coaxial Linear Motor for Electromagnetic Launchers

This paper deals with a new coaxial linear permanent magnet motor. For a designed physical model of this motor, the representative magnetic spectrums are determined: the spectrum of the excitation field provided by cylindrical permanent magnet, and the spectrum of total magnetic field given by superposition of permanent magnet field and of energizing coil field.

Untethered Microrobots Actuated With Focused Permanent Magnet Field

This paper investigates the actuation of untethered microrobots with a focused magnetic field generated by a permanent magnet wand. The microrobots are chrome-steel spheres or Neodynium cubes with a size of 250 μm, which perform desired planar motions directed by the movement of the wand. We propose and evaluate novel methods to enhance the focused magnetic field of the wand by sharpening its tip, increase microrobot velocities via novel mechanical amplifiers, and reduce environmental forces via inexpensive anti-friction coatings. We document results of automated operation and teleoperated control of the microrobot during competition at the Mobile Microrobotics Challenge (MMC) held in 2013. Experimental results from the mobility and microassembly challenge indicate an excellent degree of precision motion control over the robot, at a price of a slightly lower maximum speed when compared to conventional electromagnetic actuation.

Modeling the Magnetic Performance of a Fast Pneumatic Brake Actuator

A novel pneumatic valve was constructed to improve the response of air-actuated brakes for heavy vehicles to demand pressures generated during electronically controlled braking by an order of magnitude. Investigations were made into the interactions between the magnetic, mechanical, and electrical subsystems of the valve with a view toward informing design optimization. The valve was modeled using a magnetic circuit approach. The quasi-static model included the influences of the permanent magnet, field-line fringing, saturation, and the coil. Mechanical forces outputted by the model matched physical measurements with an error smaller than 10%, and magnetic fluxes throughout the circuit were generally within 20% of those found from experiments based on Faraday's law of induction, Gaussmeter measurements, and FEA simulations. A magneto-mechanical simulation of the valve switching states was created using mechanical and electrical equations, and curve-fits to the outputs of the magnetic circuit model. The simulation produced time histories of the valve's armature position that matched experimental measurements and adequately predicted working pressures. The final model required an approximation to the influence of the coil based on experimental results. Consequently, further research is recommended into the influence of solenoid coils on fringing in magnetic circuits.