THE appearance of a treatise in English upon the mathematical theory of elasticity is an event the potential importance of which may be judged by the that the author, in his frequent suggestions for collateral reading, refers to only three such, those of Southwell, Timoshenko, and Love. In spirit and content Sokolnikoff}s book differs greatly from each and all of these. It may be described by a possible sub-title: “A pure mathematician surveys topics related to certain problems in the mathematical theory of elasticity”. It is symptomatic of the change in outlook of American mathematics over the past few decades. Mathematical Theory Of Elasticity Prof. I. S. Sokolnikoff with the collaboration of Asst. Prof. R. D. Speche. Pp. xi + 373. (New York and London: McGraw-Hill Book Co., Inc., 1946.) 22s. 6d.

Mathematical Theory Of Elasticity

The unorthodox genetics of the mtDNA is providing new perspectives on the etiology of the common “complex” diseases. The maternally inherited mtDNA codes for essential energy genes, is present in thousands of copies per cell, and has a very high mutation rate. New mtDNA mutations arise among thousands of other mtDNAs. The mechanisms by which these “heteroplasmic” mtDNA mutations come to predominate in the female germline and somatic tissues is poorly understood, but essential for understanding the clinical variability of a range of diseases. Maternal inheritance and heteroplasmy also pose major challengers for the diagnosis and prevention of mtDNA disease.

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Mitochondrial DNA genetics and the heteroplasmy conundrum in evolution and disease

This article provided an overview of the field of microrobotics, including the distinct but related topics of micromanipulation and microrobots. While many interesting results have been shown to date, the greatest results in this field are yet to come.

Robotics in the Small, Part I: Microbotics

A home entertainment system for video games and other applications includes a main unit and handheld controllers. The handheld controllers sense their own motion by detecting illumination emitted by emitters positioned at either side of a display. The controllers can be plugged into expansion units that customize the overall control interface for particular applications including but not limited to legacy video games.

Video game system with wireless modular handheld controller

A game operating device (controller) includes a longitudinal housing, and a holding portion held by hand to be wrapped by its palm it is formed in the housing. A direction switch is provided on an upper surface at a position where it can be operated by thumb of the hand holding the holding portion, and a start switch and a select switch are provided backward thereof. An X button 46 and a Y button are further arranged in line on the upper surface of the housing. An imaging information arithmetic unit is provided at a front end of the housing in a longitudinal direction in such a manner that an imaging device thereof is exposed from a front-end surface. A concave portion is formed on a lower surface at a position corresponding to the direction switch. The concave portion includes a valley and two inclined surfaces. An A button capable of being operated by index finger of the hand holding the holding portion is provided on the backward inclined surface. By processing an image signal obtained by imaging an infrared ray from LED modules by the imaging device, it is possible to obtain an operation signal varying according to a position and/or attitude of the controller.

Game operating device

This paper demonstrates a method to visually measure the force distribution applied to a linearly elastic object using the contour data in an image. The force measurement is accomplished by making use of the result from linear elasticity that the displacement field of the contour of a linearly elastic object is sufficient to completely recover the force distribution applied to the object. This result leads naturally to a deformable template matching approach where the template is deformed according to the governing equations of linear elasticity. An energy minimization method is used to match the template to the contour data in the image. This technique of visually measuring forces we refer to as vision-based force measurement (VBFM). VBFM has the potential to increase the robustness and reliability of micromanipulation and biomanipulation tasks where force sensing is essential for success. The effectiveness of VBFM is demonstrated for both a microcantilever beam and a microgripper. A sensor resolution of less than +/-3 nN for the microcantilever and +/-3 mN for the microgripper was achieved using VBFM. Performance optimizations for the energy minimization problem are also discussed that make this algorithm feasible for real-time applications.

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Vision-based force measurement

Microelectromechanical systems (MEMS) gyroscopes are typically designed to measure angular rate of rotation. A measurement of the angle itself is useful in many applications but cannot be obtained by integrating the angular rate due to the presence of bias errors which cause a drift. This paper presents an innovative design for a vibrating gyroscope that can directly measure both angle and angular rate. The design is based on the principle of measuring the angle of free vibration of a suspended mass with respect to the casing of the gyroscope. Several critical challenges have to be handled before the theoretical sensing concept can be converted into a reliable practical sensor. These include compensating for the presence of dissipative forces, mismatched springs, cross-axis stiffness and transmission of rotary torque. These challenges are addressed by the development of a composite nonlinear feedback control system that compensates for each of the above effects and ensures that the mass continues to behave as a freely vibrating structure. Theoretical analysis and simulation results presented in the paper show that the gyroscope can accurately measure both angle and angular rate for low-bandwidth applications.

The development of a MEMS gyroscope for absolute angle measurement

When assembling MEMS devices or manipulating biological cells it is often beneficial to have information about the force that is being applied to these objects. This force information is difficult to measure at these scales. We demonstrate a method to reliably measure nanonewton scale forces applied to a micro scale cantilever beam using a computer vision approach. A template matching algorithm is used to estimate the beam deflection to sub-pixel resolution in order to determine the force applied to the beam. The template, in addition to containing information about the geometry of the beam, contains information about the elastic properties of the beam. Minimizing the error between this elastic template and the actual image by means of numerical optimization techniques, we are able to measure forces to within /spl plusmn/3 nN. In addition, we also discuss how this method can be generalized to measure forces in elastic configurations other than a simple cantilever beam using a micro-tweezer as an example. This provides the opportunity for this method to be used with specially designed micromanipulators to provide force as well as vision feedback for micromanipulation tasks.

Sensing nanonewton level forces by visually tracking structural deformations

An improved microactuator suspension is provided for use with high density storage media The number of microactuator elements is reduced to one and placed perpendicularly to the longitudinal axis of the suspension arm to maximize the windage and resonance performance and minimize the microactuator's contribution to bending stiffness and the off track bending component An improved electrical connection eliminates the requirement for a jumper These improvements reduce cost by reducing part count and assembly complexity

Cost reduced microactuator suspension

This paper presents a method to model the deformation of an elastic object with an artificial neural network. The neural network is trained directly from images of the elastic object deforming under known loads. Using this process, models can be created for objects such as biological tissues that cannot be modeled by existing techniques. The neural network elastic model is used in conjunction with a deformable template matching algorithm to perform vision-based force measurement (VBFM). We demonstrate this learning method on objects with both linear and nonlinear elastic properties.

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Michael A. Greminger

Papers

Vision-based force measurement

The development of a MEMS gyroscope for absolute angle measurement

Sensing nanonewton level forces by visually tracking structural deformations

Cost reduced microactuator suspension

Modeling elastic objects with neural networks for vision-based force measurement