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Control of Deep Space Formation Flying Spacecraft; Relative Sensing and Switched Information
(2005)Journal of Guidance, Control, and DynamicsSpacecraft formations in deep space can be specified in terms of the relative spacecraft positions and absolute spacecraft orientations. Accurate absolute position measurements are not available and a formation control design approach, based on relative position information, is presented. This approach exploits the redundancy inherent in a relative position specification to develop a family of equivalent control topologies for optimal ...Journal Article -
Communicating Centrality in Policy Network Drawings
(2003)IEEE Transactions on Visualization and Computer GraphicsWe introduce a network visualization technique that supports an analytical method applied in the social sciences. Policy network analysis is an approach to study policy making structures, processes, and outcomes, thereby concentrating on relations between policy actors. An important operational concept for the analysis of policy networks is the notion of centrality, i.e., the distinction of actors according to their importance in a ...Journal Article -
Controlled pushing of nanoparticles: Modeling and experiments
(2000)IEEE/ASME Transactions on MechatronicsA nano-robotic manipulation system using an atomic force microscope probe as the pushing manipulator and force and topology sensor is proposed. The task is the two-dimensional positioning of nanometer-size particles on a substrate in ambient conditions. Thus, the modeling of interaction forces and dynamics during the pushing operation is analyzed, and compared with the experimental results for an improved understanding of the nano scale ...Journal Article -
Evidence for van der Waals adhesion in gecko setae
(2002)Proceedings of the National Academy of Sciences of the United States of AmericaGeckos have evolved one of the most versatile and effective adhesives known. The mechanism of dry adhesion in the millions of setae on the toes of geckos has been the focus of scientific study for over a century. We provide the first direct experimental evidence for dry adhesion of gecko setae by van der Waals forces, and reject the use of mechanisms relying on high surface polarity, including capillary adhesion. The toes of live Tokay ...Journal Article -
Atomic force microscope probe based controlled pushing for nanotribological characterization
(2004)IEEE/ASME Transactions on MechatronicsUsing an atomic force microscope (AFM) probe as a nanomanipulator, micrometer- and nanometer-sized objects, especially particles, are pushed on substrates for characterizing the object-substrate friction parameters and behavior in various environments, e.g., air, liquid, and vacuum. Two possible nanotribological characterization methods are proposed in this paper: 1) sliding the micro/nano-object on the substrate while it is attached to ...Journal Article -
A legged anchoring mechanism for capsule endoscopes using micropatterned adhesives
(2008)IEEE Transactions on Biomedical EngineeringThis paper presents a new concept for an anchoring mechanism to enhance existing capsule endoscopes. The mechanism consists of three actuated legs with compliant feet lined with micropillar adhesives to be pressed into the intestine wall to anchor the device at a fixed location. These adhesive systems are inspired by gecko and beetle foot hairs. Single-leg and full capsule mathematical models of the forces generated by the legs are analyzed ...Journal Article -
A biomimetic climbing robot based on the gecko
(2006)Journal of Bionic EngineeringThe excellent climbing performance of the gecko is inspiring engineers and researchers for the design of artificial systems aimed at moving on vertical surfaces. Climbing robots could perform many useful tasks such as surveillance, inspection, repair, cleaning, and exploration. This paper presents and discusses the design, fabrication, and evaluation of two climbing robots which mimic the gait of the gecko. The first robot is designed ...Journal Article -
Vision-based feedback strategy for controlled pushing of microparticles
(2008)Journal of Micro-Nano MechatronicsA strategy for controlled pushing is presented for microassembly of 4.5μm polystyrene particles on a flat glass substrate using an atomic force microscope probe tip. Real-time vision based feedback from a CCD camera mounted to a high resolution optical microscope is used to track particle positions relative to the tip and target position. Tip–particle system is modeled in 2D as a non-holonomic differential drive robot. Effectiveness of ...Journal Article -
Preface to the Journal of Micro-Nano Mechatronics
(2008)Journal of Micro-Nano MechatronicsOther Journal Item