Open loop oscillatory control for electromagnetic actuated microgrippers

Pull-in instability strictly limits the mobile length of electromagnetic actuators. This issue has been a great restriction for a class of electromagnetic linear/torsion actuators, which often appear in micro-scale systems. In our previous research, the open loop oscillatory control was successfully applied to a prototype model of an electromagnetic actuator, and drastically extended the mobile length while averting the pull-in instability. As a more practical model, this paper deals with a scaled-up macro model of an electromagnetic gripper, which is comprised of a solenoid and a permanent magnet supported by a cantilever. The electromagnetic force is numerically estimated by the finite element method and modeled as a function of the gap. Simulation and experiment results show that our approach is promising to extend the mobile length of analogue tuned electromagnetic linear actuators.