A Generalized Approach for the Control of MEM Relays

In this paper, we show that voltage-controlled, electrostatic and electromagnetic micro-relays have a common dynamic structure. As a result, both types of microelectro-mechanical (MEM) relays are subject to the nonlinear phenomenon known as pull-in, which is usually associated with the electrostatic case. We show that open-loop control of MEM relays naturally leads to pull-in during the relay closing. Two control schemes - a Lyapunov design and a feedback linearization design - are presented with the objectives of avoiding pull- in during the micro-relay closing and improving the transient response during the micro-relay opening. Simulations illustrate the performance of the two control schemes in comparison to the typical open-loop operation of the MEM relay.