Denny K. Miu

Out-of-plane permalloy magnetic actuators for delta-wing control

INTRODUCTION The goal of this project is t o demonstrate that a collection of micro-machined actuators can control a macro object, provided that a proper controlling mechanism exists. In our case, we intend t o use a linear array of out-of-plane magnetic actuators t o crea te a rolling moment on a tail-less delta-wing model, utilizing a known mechanism in delta-wing theory that allows micro actuation to have an amplified, macro effect. A delta-wing is one of the fundamental configurations for generating lift forces and its aerodynamic control is of great importance t o the aeronautics society [1,2]. When laminar air flow hits the two leading edges of the wing at a certain angle-of-attack (30 in our case, Fig. la,b), two counter-rotating leading-edge vortices are separated from the laminar flow and propagate over the wings top (Fig. IC). These two high-momentum, low-pressure vortices contribute identical vortex lifting forces on the two sides of the wing, the sum of these being -40 % of the total lifting forces. The strength and position of these two vortices are determined by the boundary layer conditions near their separation points. A boundary layer is roughly 1-2 mm thick at a windtunnel flow speed of less than 20 m/s; the thickness will decrease when the flow speed is increased. Two linear arrays of surface micro-machined out-ofplane actuators (micro-flaps) are placed along two leading edges at the bottom of the wing (Fig. Id) . When un-deflected, flap arrays remain a t the bottom of the boundary layer, having no effect on the flow and vortices; when one array is deflected downward, however, it interacts with the boundary layer and changes the separation point of the corresponding leading-edge vortex. The span-wise vortex structures over the top of the wing become unbalanced, and an overall rolling moment can be created. The delta-wing has a 38-cm span and a 67 O top angle; it is tested in a wind-tunnel with a top speed of 20 m/s. Silicon micro-machined actuators are chosen here because of their added advantages of light weight and potentially large bandwidth. To control this wing, micro-flaps are required to deflect 1-2 mm out-of-plane (or t o match the boundary-layer thickness), and withstand large aerodynamic loading on the order of several hundred pN. Magnetic actuation is used because it is known to generate stronger and longer-range forces [3, 4, 51 compared with most other driving methods. Several types of magnetic micro-actuators have been previously demonstrated, but none can readily fulfill the current system requirements. Beneck et . al. [6] performed post-processing manual attachments of permanent magnet pieces on micromachined plates and actuated the magnet with an external magnetic field generated by in-plane coils. The manual assembly is unsuitable for us because a large number of ac-

Design, fabrication, and testing of silicon microgimbals for super-compact rigid disk drives

This paper documents results related to design optimization, fabrication process refinement, and micron-level static/dynamic testing of silicon micromachined microgimbals that have applications in super-compact computer disk drives as well as many other engineering applications of microstructures and microactuators requiring significant out-of-plane motions. The objective of the optimization effort is to increase the in-plane to out-of-plane stiffness ratio in order to maximize compliance and servo bandwidth and to increase the displacement to strain ratio to maximize the shock resistance of the microgimbals, while that of the process modification effort is to simplify in order to reduce manufacturing cost. The testing effort is to characterize both the static and dynamic performance using precision instrumentation in order to compare various prototype designs. >

Silicon micromachined integrated suspension systems for magnetic disk drives

Abstract This paper presents results related to the design, fabrication and static/dynamic testing of a silicon micromachined integrated suspension system. This novel magnetic read/write head suspension with its built-in electrodes has been developed especially for automated assembly with miniaturized slider bearings. The one-piece construction silicon microgimbal and the polyimide-reinforced silicon load-beam are designed to have minimum profile, maximum pitch and roll compliances, maximum in-plane stiffness and maximum shock resistance, all of which are important operational requirements for the emerging small-form-factor magnetic recording rigid disk drive market.

Silicon Microactuators for Computer Disk Drives

Silicon micromachining will be an important manufacturing technology for future-generation, high-performance optical and magnetic storage products. In this paper, we shall present recent results related to the design and fabrication of silicon micromachined electromagnetic piggyback microactuators for significantly increasing the track density of magnetic (and potentially optical) rigid disk drives.