Recent Advances on the Design and Control of Macro/Micro Actuators

Macro/Micro actuators are comprised of two actuators connected in series with complementary characteristics: while the macro (primary) actuator possesses a long range of actuation but a slow response, the micro (secondary) actuator presents fast dynamics but short range. An improved performance is expected by a proper coordination of these actuators so that the limitations of one may be compensated by the merits of the other. This concept of parallel actuators working on the same task at the same time is widely spread in the Hard Disk Drive (HDD) industry and in academic publications, but relatively new to other potential applications. The purpose of this study is to provide an overview about the macro/micro actuation concept by addressing recent patents and scholarly articles on the subject of design, control and application of such systems.