Asymmetric shape of distal phalanx of human finger improves precision grasping

In morphology field, the functions of an asymmetric-shaped distal phalanx in human finger have only been inferred. In this study, we used an engineering approach to empirically examine the effects of the shape of distal phalanx on the ability of precision grasping. Hence, we developed artificial fingertips consisting of four parts, namely bones, nails, skin, and subcutaneous tissue, that substitute the actual human fingertips. Furthermore, we proposed a method to evaluate the grasping ability of artificial fingers. When a cylindrical object was grasped by an artificial fingertip, a pull-out experiment was conducted. Thus, the asymmetric type was found to be superior in terms of drawing force, holding time, and work of friction than the symmetric type. Our results clearly demonstrate that the asymmetric shape, particularly the mirror-reversed shape of the distal phalanx, improves the ability of precision grasping and suggests that the human distal phalanx is shaped favorably for object grasping.

Drag of a cylindrical object in a two-dimensional granular environment

The drag of a cylindrical object in a two-dimensional granular environment is numerically studied. It is found that the drag law is fitted by the sum of the yield force and the dynamic force, the latter of which is reproduced by a simple collision model. The angular dependence of the radial stress on the surface of the object is given by the Gaussian below the yield force. The probability of the velocity drops of the object is investigated above the yield force, where this probability is independent of the packing fraction and the drag force.

STUDY OF THE RADAR CROSS SECTION OF SIMPLE BODIES

Рассмотрены картины моностатической эффективной площади рассеяния для простых геометрических тел. Для простой металлической пластины был произведен теоретический расчет значения эффективной площади рассеяния (ЭПР), а также произведено моделирование с использованием метода Вейланда, по результатам которого были доказаны точность и эффективность моделирования в специализированном программном обеспечении (ПО). Для определения эффективной площади рассеяния шара рассматривались три случая: когда размеры шара превосходят длину волны; размеры малы, а в качестве материала изготовления выбран проводник; при сохранении размеров материал изготовления заменяется на диэлектрик - стекло. По полученным результатам сделаны выводы о важности сопоставления длины волны с геометрическими размерами тела, а также о положительном влиянии диэлектрических материалов на значение ЭПР. При исследовании цилиндра рассматривались два случая, которые могут возникнуть при исследовании ЭПР цилиндрического объекта, а именно, когда волна падает на боковую поверхность тела и на верхнюю грань. Было показано, что наихудшие значения эффективной площади рассеяния наблюдаются при падении плоской волны на верхние - идеально плоские грани цилиндра. Приведены результаты в виде картин моностатической ЭПР, максимальных значений эффективной площади рассеяния The article considers the figures of the monostatic effective scattering area for simple geometric bodies. For a simple metal plate, a theoretical calculation of the RCS value was carried out, as well as modeling using the Vayland method, the results of which proved the accuracy and efficiency of modeling in specialized software. To determine the effective area of dispersion of the ball, three cases were considered when the dimensions of the ball exceed the wavelength; the dimensions are small, and a conductor is selected as the material of manufacture; while maintaining the dimensions, the material of manufacture is replaced by glass. Based on the results obtained, conclusions are drawn about the importance of comparing the wavelength with the geometric dimensions of the body, as well as the positive effect of dielectric materials on the value of the RCS. In the study of the cylinder, two cases were considered that can arise when studying the RCS of a cylindrical object, namely, when the wave falls on the side surface of the body and on the upper face. It was shown that the worst values of the effective scattering area are observed when a plane wave is incident on the upper, ideally flat, faces of the cylinder. The results are presented in the form of monostatic RCS patterns, maximum values of the effective scattering area

TECHNICAL VISION SYSTEM WITH ARTIFICIAL INTELLIGENCE FOR CAPTURING CYLINDRICAL OBJECTS BY ROBOT

The article presents a variant of working with a system of technical vision, which recognizes cylindrical objects. This vision system based on artificial intelligence, which allows you to determine the circles in the image. The coordinates of the value of the circle are necessary for the exact positioning of the robot manipulator. The calculation of the gradient and threshold separation determine the gaps in the intensity of the image of the object. These methods define pixels lying on the border between the object and the background. The further process consists in connection of the segments of a contour separated by small intervals, and in association of separate short segments. Thus, contour detection algorithms accompanies by procedures for constructing object boundaries from the corresponding pixel sequences. The resulting image has sufficient information for artificial intelligence analysis to detect the circle. The software is developed and experimentally tested in operation. The operation of the technical vision system experimentally tested in the work, namely the capture of a cylindrical object. Work vision systems has been experimentally proven to work and is passionate cylindrical object. The coordinates of the value of the circle, which are necessary for the exact location of the robot manipulator were determined by artificial intelligence in 41 milliseconds. The obtained coordinates were transmitted to the microprocessor to adjust the position of the manipulator. The robot accurately captured a cylindrical object.

Towards Creating Inter-Finger Kinematic Models for Natural Coordination Derived From Grasping of Virtual Objects

This paper builds up on a recently developed novel planar inter-joint finger kinematic model for human hand configurations, which applies to the realization of a naturalistic human finger motion. The model is a function of the finger anthropomorphic data and is derived based on the geometry of a hand shape grasping a virtual cylindrical object. Unlike well-known inverse kinematics models, the inter-joint model is capable of describing the natural rotation configuration of the joints of a long finger independently by a single parameter, the radius of the cylindrical object. A novel inter-finger coordination model, based on the inter-joint model is proposed and experimentally tested. The preliminary results show that the model has the potential to simulate naturalistic human hand grasping motion. The merit of the proposed inter-finger coordination model is in its simplicity when used in hand-exoskeleton design assessment and naturalistic hand trajectory planning applications, among others. We would like to note that this paper is the first step towards exploring future simplified combined design-control strategies for the development and assessment of mechanical limbs for naturalistic movement.