An Application of the Stability Circle to the Design of MEMS Technology Based Systems With Floating Center Rotary Comb Drives

Abstract Based on the classic plane rigid motion theory, this article suggests how to use a well-known locus of points, namely, the inflection (or stability) circle, with specific second order path curvature characteristics, to optimize the positioning of a so-called floating center rotary comb drive (FCRCD) that could be employed in any microelectromechanical system (MEMS) with the aim of improving the actuation force or torque. In the first part of the paper, the new concept FCRCD is briefly described, by underlying its efficacy to improve the actuating torque in the embedding microsystem. In fact, FCRCD actuators have been conceived to increase the available input power that provides motion. The second part of the paper will describe how the inflection circle can be used to detect the most feasible or unfeasible zones where to place the FCRCD in the microsystem. Being only at the second order of the plane curve theory, the inflection circle is considered rather elementary a tool. Nevertheless, this paper will show how such fundamental locus of the plane will be used to identify the critical region where a FCRCD should not be placed. The adopted method recalls very much the reasons why the inflection circle has been also referred to as stability circle.