Eniko T Enikov

Abstract:

Tactile perception of complex symbols through tactile stimulation is an exciting application of a phenomenon known as tactile illusion (TI). Sensation of motion on the skin can be produced by a limited number of discrete mechanical actuators applying light pressure over the skin. This phenomenon can thus be used as a neurophysiological testing tool to determine central and peripheral nervous system injury as well as providing an additional human-machine communication channel. This paper describes the development of a 4 × 5 actuator array of individual vibrating pixels for fingertip tactile communication. The array is approximately one square centimeter and utilizes novel micro-clutch MEMS technology. The individual pixels are turned ON and OFF by pairs of microscopic composite thermal actuators, while the main vibration is generated by a vibrating piezo-electric plate. The physiological parameters required for inducing tactile illusion are described. The fabrication sequence for the thermal micro-actuators along with actuation results are also presented.

Abstract:

A composite actuator based on a polymer electrolyte and metal electrodes is described. Electrode deposition is described qualitatively with corresponding experimental results. A general continuum model describing the transport and deformation of solid polymer electrolyte processes is developed. The formulation is based on global integral postulates for the conservation of mass, momentum, energy, charge, and the second law of thermodynamics. The global equations are then localized in the volume and on the material surfaces bounding the polymer. The model is simplified to a three component system of a fixed negatively charged polymeric matrix, diffusing hydroxonium ions, and free water within the polymer matrix. Contrary to the existing electrostatic models, the deformation is attributed to water induced swelling. The proposed internal pressure based model includes the stress relaxation phenomenon due to water redistribution governed by Darcy's law.

Abstract:

This paper is focused on the design of metal (Ni) electro-thermal micro-actuators, fabricated via a single electro-plating step. Analytical and finite-element solutions of the electro-thermal and thermo-elastic problems are presented to aid in the design of the devices. A separate section is devoted to the problem of displacement determination using charge sensitive amplifiers for high-precision capacitance measurements. Finally, a possible future use of these actuators in impedance-based biosensors is outlined. copyright The Electrochemical Society.

Abstract:

Without control, the desired motions of machines do not occur, and the desired equilibria and stationary motions are often unstable. Human operator or computer control may be needed to control and stabilize these machines. An important common feature of both analog and digital controllers is the time delay that is introduced into the system. Even when these delayed systems should be stable, the experiments show small stochastic oscillations around the desired motion, as are often experienced in robotics. In case of the stabilization of an inverted pendulum, the analysis of the equation of motion shows that chaotic vibrations occur around the equilibrium even when stochastic effects related to human control are not present. In advanced design work of digitally controlled machines, it is vital to know the characteristics of this chaotic behavior. The estimation of the distribution of vibration amplitudes and the frequency range should be available at the design stage. This initiates the analysis of the so-called microchaos or μ-chaos.

Abstract:

This article introduces an optical device for measuring and recording the vibrations during milling. The constructed apparatus is able to discriminate between stable cutting and chatter vibration. A review of various chatter detection methods is presented. It lists basic numerical approximation methods to predict chatter and the devices used to detect unstable cutting. A discussion on the importance of experimental detection versus theoretical predictions is also included. The article further presents the measurement setup, its basic components, and their parameters along with the basic principles of the measurements and the theoretical framework of the stability analysis. The theoretical framework is then applied to show the chatter determining frequencies and to determine what has to be detected during the measurements. Experimental results for slotting and down milling with different immersion ratios are also presented. These include stability maps based on the power spectrum density (PSD) graphs of the collected data and confirmed by photographs of the cut surfaces. The conclusion summarizes the results, and describes advantages and disadvantages of the setup. © Taylor & Francis Group, LLC.