Author: Abdullah SOFIYEV
Abstract: The free vibration analysis of the sandwich complete conical shell with functionally graded materials (FGMs) facings based on the classical shell theory (CST) is studied. The basic equations of metal-rich truncated conical shells with FGMs facings are derived and solved by employing Galerkin method. The closed form solution for dimensionless frequency parameters of the sandwich complete conical shell with FGM facings is found. The effects of kinds of FGM facings and variation of thickness of facings on the magnitudes of dimensionless frequency parameters are studied in numerical analysis part.
Keywords: Functionally graded materials, FGM facings, sandwich complete conical shell, metal-rich core, free vibration, frequency parameters
Author: Rasim ALIZADE
Abstract: This paper focuses on the systematic type synthesis of parallel robot manipulators by using new structural formulas based on the screw theory. New structural formulas as a total number of screw in kinematic pairs, number of screws with variable pitch, total number of screws that represent the contact geometry of lower and higher joint elements, mobility equation for robot manipulators, dimension of the closed loop, motion of end effector of parallel manipulator, number degree of freedom of kinematic pairs, refers to find the kinematic structure of robot manipulators realizing a specified motion requirement. Twenty kinematic pairs with structural parameters are introduced. History of six structural formulas using for structural synthesis of parallel robot manipulators from space and different subspaces are presented as a table with equations, authors, years and some commentaries. The structural synthesis approach is based on the elementary notions of screw theory. Using the proposed of structural formulas approach, families of platform manipulators are constructed from a set of structural units. This paper is appropriate for engineers with interest in robotics, rovers, space docking parallel manipulators and screw theory.
Keywords: Kinematic pair screws; Motion of end effector; Screws with variable pitch; Dimension of closed loop.
Author: Isa KHALILOV, Beyali AHMEDOV, Anar HAJIYEV
Abstract: The article deals with the issues of quantitative assessment of the internal resistance of oil in sliding bearings of the new constructive solution of two-line three-stage reducer intended for use in transmission mechanisms of machines and devices. Based on the analysis of possible kinematic diagrams of the new constructive solution of reducer, it was determined that the directions of rotation of the driving and driven shafts coincide with the directions of rotation of block gears mounted on sliding bearings. In this case, the resistance in the sliding bearings becomes a useful driving force, which becomes a useful factor characterizing the internal driving force of the oil. This improves the reliability of the mechanism, as well as significantly reduce the energy consumption of the mechanical transmission. Based on the results of calculations, it was determined that the efficiency factor of the new constructive solution of a three-stage reducer is about 2% higher than in classic reducers.
Keywords: new constructive solution, sliding bearings, double gear, block, driving force, efficiency factor, oil layer, angular velocity, resistance force.
Author: Alishir ALIFOV, Mikhail MAZUROV
Abstract: The interaction of self-oscillations and parametric oscillations under the influence of delayed elastic and damping forces in the presence of a limited power energy source in the system is considered. To construct solutions to a nonlinear system of equations, the direct linearization method was used, which contains the linearization accuracy parameter. Using this method, equations of non-stationary and stationary motions are obtained to determine the amplitude, phase of oscillations and the speed of the energy source. Based on the Routh-Hurwitz criteria, the stability of stationary modes of motion is considered and the stability conditions are derived. In order to obtain information about the effect of elastic delays and damping on the dynamics of the system, calculations were performed for various combinations of their values. The corresponding amplitude-frequency characteristics and a graph of the load on the energy source from the side of the oscillatory system are constructed.
Keywords: self-oscillations, parametric oscillations, energy source, limited power, delay, elasticity, damping, method, linearization.
Author: Erkin GEZGIN
Abstract: Parallel to the rapidly developing technology, robot manipulators, whose areas of usage have continuously been expanded from the last periods of past century, have taken part in many different successful applications. Thanks to its increasing significance, nowadays medical science is one of the primary areas of those applications. Thus, this study targets mainly the field of medical science. Within the scope of this paper, six degrees of freedom hybrid robot manipulator with large workspace and adequate precision was introduced and equipped with dual actuators in its two Cartesian axes for possible haptic integration for the future. Target hybrid manipulator was designed in such a way that it can be used in various related medical applications such as teleoperations in robotic surgery, surgical navigation, dental and laparoscopic simulations. After the structural design part was completed, direct and inverse kinematic analysis procedures were carried out and by using rapid prototyping techniques the manipulator was manufactured.
Keywords: Hybrid Robot Manipulators, Teleoperation, Kinematic Analysis
Author: Nazim MIR-NASIRI, Hudyjaya SISWOYO JO
Abstract: The paper describes conceptual design, control strategies and partial simulation for a new fully autonomous lower limb wearable exoskeleton system for human motion enhancement that can support its weight and increase strength and endurance. During the last decade, researchers have focused on the development of lower limb exoskeletons for power augmentation for military or medical assistance. Various problems remain to be solved where the most important is the creation of a power and cost efficient system that will allow an exoskeleton to operate for extended periods without being frequently recharged. The designed exoskeleton is enabling to decouple the weight/mass carrying function of the system from the forward motion function which reduces the power and size of propulsion motors and thus the overall weight, cost of the system. The decoupling takes place by blocking the motion at knee joint by placing passive air cylinder across the joint. The cylinder is actuated when the knee angle has reached the minimum allowed value to bend. The value of the minimum bending angle depends on usual walk style of the subject. The mechanism of the exoskeleton features a seat to rest the subject’s body weight at the moment of blocking the knee joint motion. The mechanical structure of each leg has six degrees of freedom: four at the hip, one at the knee and one at the ankle. Exoskeleton legs are attached to subject legs using flexible cuffs. The operation of all actuators depends on the amount of pressure felt by the feet pressure sensors and knee angle sensor. The sensor readings depend on actual posture of the subject and can be classified in three distinct cases: subject stands on one leg, subject stands still on both legs and subject stands on both legs but transit its weight from one leg to other. This exoskeleton is power efficient because electrical motors are smaller in size and did not participate in supporting the weight like in all other existing exoskeleton designs.
Keywords: Energy efficient system, exoskeleton, motion enhancement, robotics
Author: Leonid SHIPULIN, Evgeniya OBUKHOVA, Arnold FROLOV
Abstract: An overview of the standard cycles used in the preparation of control programs for cylindrical grinding machines with the Siemens SINUMERIK 802D sl CNC system, as well as the problems associated with the assignment of their parameters, is carried out. The developed software for assigning the parameters of standard cycles used in the preparation of control programs for cylindrical grinding machines with the Siemens SINUMERIK 802D sl CNC system is being carried out.
Keywords: cylindrical grinding, automatic cycles, parameters of grinding cycles.