The Atomic Force Microscope as a Machine Tool: Modelling, Robust Control Design, and Hardware

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9632820 Dahleh Precision machining is an important emerging technology with manufacturing applications in diverse fields such as optics, microelectronics, magnetic and optical recording as well as sensors and actuators. With trends in miniaturization, the need to develop tools to shape materials as micrometer and nanometer scales is expected to keep increasing. In view of this, we propose to design, fabricate and use a machine tool which is based on the concept of the atomic force microscope (AFM). The AFM is a recent invention which has so far been used to image surfaces with atomic scale lateral and vertical resolution. It scans a sharp stylus probe across a sample surface while maintaining a constant contact force between the probe tip and the sample surface through a feedback control system. We propose to use the stylus probe as a cutting tool with the system having the following features--(1) depths-of-cut will range from 1nm - 10um with surface finishes ranging from 0.1 nm -1 nm; (2) normal and tangential forces on the tool will be simultaneously measured with 10 nN to 1 uN resolution; (3) tool-workpiece relative motion can be rotational and/or translational; (4) closed loop robust control will maintain constant either the tool-sample force or the tool-sample distance; (5) workpiece surface can be imaged with spatial and vertical resolution in 1nm range; (6) workpiece surface can be patterned to any desired shape - rotationally symmetric or non-symmetric; (7) machining can be done with lateral resolution in the 30 nm - 10 um range. These features will make the proposed design superior to existing precision machining tools. The objectives of this project are two-fold -- (1) to develop an automated and versatile precision machining and imaging tool; (2) to build a prototype device for the study and validation of control methodologies, identification methods, and the interface of control and the mechanics of machining at a nano-scale. ***