Guskov

pp. 162-174

pp. 1-22

pp. 45-59

pp. 202-233

pp. 152-174

pp. 240-265

pp. 473-488

pp. 298-317

pp. 250-268

pp. 201-220

pp. 842-857

pp. 696-707

The mechanical heart support/replacement system - ventricular assist device (VAD) design task is considered in this article. Relevance of research in this area is due to high percentage of people suffering from heart diseases. The cause of every 5th death in the world is heart failure. Currently, a number of VAD models have been created some of which are successfully used in medical practice. Over years of research in this area the general concept of VAD development has been formed: requirements to systems have been established, approaches to the tasks solution have been developed, certain results have been received and existing lacks of VAD systems have been revealed. Rapidly developing technologies give more and more opportunities for solving the existing problems. This work presents an analysis of the problem of VAD systems development today. Biomedical and technical requirements to VAD systems are systematized, classification of the problems arising in the design process is carried out, finally, trends and new developments in this area are discussed.

Measurement of cutting forces is an important component for development and validation of manufacturing processes. To use generally accepted direct measurement systems available for this purpose is often impossible. This paper suggests an indirect method to estimate the cutting force when turning a thin-walled cylindrical shell. The method is based on the displacement measurements of the flexible workpiece. Furthermore, when it comes to the flexible workpieces turning, cylindrical shells in particular, there is a need to use non-contact displacement sensors. This paper considers a specific manufacturing system in which two radial displacement sensors are located close to the free end of a cylindrical shell, the opposite end of which is rigidly fixed in a chunk of a lathe. Measuring the radial and the circumferential components of the cutting force is under study. The model has been developed in a quasi-static approximation. An experimental case has been analyzed using the proposed method. Optimization of the angular location of two displacement sensors has been proposed based on the idea of minimizing the condition number of the linear transformation matrix.

A mathematical model was developed for plane aerostatic bearings with porous deboosters; this model allows to determine the main performance characteristics such as damping stiffness of load capacity in linear and angular directions and a consumable air flow. Experimental determination of permeability inhomogeneity for porous graphite deboosters was conducted. Influence of permeability variation on characteristics of an aerostatic bearing was evaluated by means of calculations with maximum and minimum values of the permeability index. This influence appeared to be smaller with a constant aerostatic gap than with constant load. On the basis of the obtained results, recommendations on manufacturing plane aerostatic bearings were given.

This paper deals with the similarity theory and dimensional analysis for investigating cutting forces – particularly during drilling. Use of dimensionless groups allows one to obtain relations which are independent of unit systems, reduce the number of significant variables; it also helps to avoid influence of measurement bias on the dimension of physical relationships and ensure comparability of experimental results obtained under various conditions by different authors. Eleven dimensionless quantities for cutting process characteristics were proposed. Based on the experimental data for 3 types of drills, polynomial and power cutting laws for both axial force and torque were derived. Extension of those relationships to the case of vibrational drilling was considered; a method of applying existing relationships to obtaining of cutting laws in the form of dimensionless criteria was proposed.

This article presents a simulation of kinetostatics of a 7-DOF surgical robotic manipulator by the example of sternotomy. Motion of the robot is performed along a predetermined path in the global coordinate system. The numerical simulation was conducted in MATLAB^®Robotics Toolbox + Simulink^® program package. The same motion was investigated in SolidWorks^® for calculating flexibility matrices with the use of the finite-element method. Flexibility matrices for the point of load application were found for 11 successive positions of the robot. Compliance matrices were obtained using ABAQUS CAE® software.

In this paper a point-to-point motion problem was considered by the example of brain biopsy. It was emphasized that this operation requires exceptional end-effector positioning accuracy to the target point. End-effector motion was considered as point-to-point Cartesian trajectory tracking. The desired trajectory in Cartesian space was transformed to joint coordinate trajectory in joint space through solving the inverse kinematic problem. Computed-torque control was selected as a control scheme. Desired joint positions, velocities and accelerations were input signals for the inverse dynamic problem with the control low to compute joint torques required for implementing the required end-effector motion. Current joint position, velocity and acceleration were computed through solving the direct dynamic problem. High point-to-point motion accuracy indicators prove adequacy of the available robotic manipulator model and suitability of the selected control scheme. The task of numerical simulation was solved with the use of MATLAB^® Robotics Toolbox + Simulink^®.

During surgical operations with the use of a robot–manipulator, control actions are managed by force effects in the area of the surgical operation. The constructional design of the robot is chosen according to the technological requirements for implementation of specific movements. It turns out that when a force is applied to the tool, displacement of the force application point can be non-collinear to the force vector. If interaction between a surgical instrument and the operation object can be reduced to a concentrated force, it is necessary to choose a beneficial robot configuration to avoid lateral offset. In this configuration the force vector must be aimed to the proper direction of the robot compliance matrix in the force application point. The proposed calculation method helps to construct a working configuration of the robot with respect to minimization of possible spurious derivation of the instrument from the requested trajectory.

A description of carrying out brain biopsy was examined. It is emphasized that one of the major problems is to position the instrument precisely and to maintain a safe trajectory while carrying out the operation. A disadvantage of traditional stereotaxic systems, apart from constructive disadvantages (long preparation and repeated operations have to be carried out in case of multi-target procedures), is that it doesn’t have the ability to observe the effectiveness of surgical manipulation in the target object in real time and, therefore, to reveal ongoing intracranial complications. Modern technologies which use robotic-manipulators allow to increase accuracy, speed and safety in high-precision operations simultaneously. The need for accuracy in positioning the instruments and automated support system are discussed in detail.

The method of stabilization of the trunk pump unit (TPU) was presented in this article. Since TPU increased oil pressure during its transportation through the pump, the heavy shear force arose. This force was applied to pipes, which had been jointed to the pump, and to unit frame. To reduce the influence of negative shear force it was offered to compensate this force with system of hydrocylinders

The authors proposed a simplified segment-model of spherical aerostatic bearings which allows to determine static and dynamic behaviour of bearings. The model is based on two physical assumptions: the number of estimated segments is considered large, and the speed of tangential bearing surfaces is considered negligibly small. Bearing reactions are estimated on the basis of a series of preliminary calculations of air pressure in a separate segment field. The pressure field estimation is performed with the finite-element method in MATLAB program in a nonlinear formulation. The proposed model was tested on spherical aerostatic bearings with porous boost limiters developed for the high-precision nonferrous metal-turning work spindle. The segments number influence on accuracy of load characteristics is estimated.

In article the new approach to modelling of parametres of the human muscle describing a condition of a muscle (weakened or strained) is offered. The universal curve gives possibility to compare various muscles in relative units, as

In work the possible scheme очувствления the surgical tool for carrying out of operations in vessels is considered. The offered scheme allows the surgeon in operating conditions (on line) to receive the information on level of working efforts in the field of surgical intervention. It can be used for designing очувствленных working bodies of robots – manipulators of surgical appointment. A working out main objective is creation of the system, allowing to warn possible mechanical damages of biological fabrics in the course of carrying out of surgical operation.