Characterization, modeling and control of the uWalker - a micro actuator for data storage

We, people, always want more. Ever increasing demands for computing performance and storage capacity call for disruptive technologies of digital data storage. An additional fact is the miniaturization of many consumer electronics devices that are present on the market. The combination of these two ingredients has raised discussions whether for instance the hard-disk storage principle could be partially substituted by new technologies, which better meet the desired present and future specifications. uSPAM (Micro Scanning Probe Array Memory) is one of the projects related to data storage, where we seek to build a prototype of a probe storage read and write device. The work presented in this thesis is on two-dimensional positioning in the read/write system. The first necessary step was to characterize the uWalker, an existing micro electro-mechanical actuator, as this is considered to be the basic stone for the positioning system in uSPAM. Based on the knowledge obtained by measurements, a number of physical models were developed and simulated. These models are able to predict the effects of varying actuator dimensions and or material properties on the overall performance. Such predictions are very interesting, because they accelerate the development of the positioning system considerably. Based on simulation results, a range of new devices were designed and tested. Many of them are based on the original uWalker actuator and now include electrostatic sensors, 2D motion or other features. The control of such MEMS actuators is a totally different topic, with lots of opportunities for future research. Real time closed-loop control in MEMS proves a hard task, especially the integration of sensors, actuators and the control system in the small volume which is required. Both open- and closed-loop control ideas are worked out and the open-loop case is validated.