Modeling and Analysis of Magnetic Micro Impact Drives

Authors: Zoltán Nagy (IRIS), Dominic Frutiger (IRIS), Remco Leine, Brad Nelson (IRIS)

This research project is a joint project with the Institute of Robotics and Intelligent Systems (IRIS) of the ETH Zurich. A wireless resonant mechanical actuator, called WRMMA, has been developed by the Multi-Scale Robotics Lab of the Institute of Robotics and Intelligent Systems. The WRMMA consists of two nickel masses connected through a gold spring and has overall dimensions of 300 × 300 × 50μm³. One mass—the body—rests on a gold support structure which in turn has frictional contact with the substrate, whereas the other one—the hammer— is lifted above the ground and can move freely without friction. Initially nonmagnetic, the nickel bodies become magnetized when an external magnetic field is applied. As a result, an attractive magnetic force arises between the two opposing magnetic poles of the nickel bodies. Then, pulsed magnetic fields are used to induce oscillatory motion and it is assumed that occurring impact between the hammer and the body drives the robot forward. An additional electrostatic clamping force between the body and the ground allows to arbitrarily rectify the oscillation by effectively controlling the friction between the robot and the ground.

In this research project, the WRMMA is modeled and analyzed numerically by using tools from the Nonsmooth Dynamics community (e.g. Moreau's timestepping method, set-valued force laws) and bifurcation theory. The simulations are validated with experimental data available for the tethered mode and in literature. The influence of the system parameters on the performance, e.g. the velocity of the robot, is investigated. 

Link: webpage of the Multi-Scale Robotics Lab on Wireless Resonant Magnetic Actuators for Untethered Mobile Microrobots

Left: A photograph of the WRMMA (photo by the Institute of Robotics and Intelligent Systems), Right: model of the WRMMA

Publications:

Nagy, Z., Frutiger, D.R., Leine, R.I., Glocker, Ch., Nelson, B.J.: "Modeling and Analysis of Magnetic Micro Impact Drives", IEEE International Conference on Robotics and Automation, Anchorage, USA, 2010.