Behavior Of Rotating Magnetic Microrobots Above The Step-Out Frequency With Application To Control Of Multi-Microrobot Systems

This paper studies the behavior of rotating magnetic microrobots, constructed with a permanent magnet or a soft ferromagnet, when the applied magnetic field rotates faster than a microrobot's step-out frequency (the frequency requiring the entire available magnetic torque to maintain synchronous rotation). A microrobot's velocity dramatically declines when operated above the step-out frequency. As a result, it has generally been assumed that microrobots should be operated beneath their step-out frequency. In this paper, we report and demonstrate properties of a microrobot's behavior above the step-out frequency that will be useful for the design and control of multi-microrobot systems. (C) 2014 AIP Publishing LLC.