WRIST REHABILITATION WITH MANIPULATOR TO PERFORM PASSIVE AND ACTIVE EXERCISES

The paper characterizes basic dysfunctions and diseases of a human wrist as well as describes the mechanics and pathomorphology of the human hand. The radial-carpal joint was analyzed in terms of his ranges of motion. The results of the analysis, i.e. the number of degrees of freedom for a free hand, are included. The concept of manipulator construction for optimal rehabilitation of the wrist was developed. Expected effects of the exercises, which can be implemented on the designed manipulator, were also described. A comparative analysis of other appliances supporting the rehabilitation of the human upper limb were presented. The main purpose of the designed manipulator was to gain full control of implementation of exercises performed by the patient and to archive and precisely track the progress in the rehabilitation. An important feature of the designed manipulator is its versatility enabling its use for: exercises of both hands (left and right) with the repetitive movements, choose of exercises (active and passive movements), choose of the degree of disability of the patient

A hybrid multi-objective evolutionary approach for optimal path planning of a hexapod robot

Hexapod robots are six-legged robotic systems, which have been widely investigated in the literature for various applications including exploration, rescue, and surveillance. Designing hexapod robots requires to carefully considering a number of different aspects. One of the aspects that require careful design attention is the planning of leg trajectories. In particular, given the high demand for fast motion and high-energy autonomy it is important to identify proper leg operation paths that can minimize energy consumption while maximizing the velocity of the movements. In this frame, this paper presents a preliminary study on the application of a hybrid multi-objective optimization approach for the computer-aided optimal design of a legged robot. To assess the methodology, a kinematic and dynamic model of a leg of a hexapod robot is proposed as referring to the main design parameters of a leg. Optimal criteria have been identified for minimizing the energy consumption and efficiency as well as maximizing the walking speed and the size of obstacles that a leg can overtake. We evaluate the performance of the hybrid multi-objective evolutionary approach to explore the design space and provide a designer with an optimal setting of the parameters. Our simulations demonstrate the effectiveness of the hybrid approach by obtaining improved Pareto sets of trade-off solutions as compared with a standard evolutionary algorithm. Computational costs show an acceptable increase for an off-line path planner. © Springer International Publishing Switzerland 2016

Verification of Stress Components Determined by Experimental Methods Using Airy Stress Function

AbstractThe paper is dedicated to mathematical theory of elasticity and its relevant methods as applied for determination of plane stress state for the purposes of verification of experimental values which were determined using PhotoStress̈ method as applied for chosen samples. The paper further deals to a great extent with Airy biharmonic function as regards plane stress state in the samples with centrically placed round holes. The introductory part of the paper includes basic algorithms for solving the problems of mathematical theory of elasticity followed by descriptions of Airy biharmonic stress function in Cartesian and polar coordinates. In further parts of the paper were derived equations for the calculation of radial, circumferential and shear stress in samples with centrically placed round holes. Calculations are included in a single part of the paper together with input algorithms for calculations of radial, circumferential and shear stress. The algorithms were performed using the syntax of programming language Matlab in MATLAB/Simulink. Subsequently, the results of radial and circumferential stress calculations were depicted as 2D pictures similar to experimental samples with visualised stress functions. These were later used for the verification of values determined through an experiment

Distorsion of Isochromatic Fringes in the Process of Stress Measurement in Structural Part by Photoelasticimetry

In the article we show the possibility of distorting the results of the experiment by photoelasticity path, in case the isochromatic fringe patterns are recorded by the camera. The recording of the color spectrum may be distorted by inappropriate selection of the recording medium, which is reflected by different types of aberrations. Transferring a record to a computer allows you to automate the experiment process, thus saving time to work with isochromatic fringes. As an example, we present the experimental determination of the stresses of the rotor with a symmetrical arm. The analysis was performed using software developed by the authors. This software enables full automation of the experiment process. The rotor is investigated by the method of reflection photoelasticity. The experimental solution is realized as a case of periodically repeating dynamic effects, in which a stroboscopic source of white light is needed. The results of the experiment are compared with the numerical solution and their dependence is represented by diagram

The Use of Optical Methods in the Analysis of the Areas with Stress Concentration

Anchoring parts of technical systems are often damaged due to the heavy forces acting on these systems during their operation. For that reason, various modifications are suggested and created on the anchoring screws, which should help to reduce the mechanical stress values in a place of the first load-bearing thread of a female screw. For the determination of stress fields on the surface of a plane model of a threaded joint, two non-contact optical methods were used – conventional transmission photoelasticimetry and modern digital image correlation

Modification of the Centre Differential Gearbox

Abstract The paper deals with the optimization of the centre differential heavy truck without a wheel reductions. Under optimization in this case means customizing cabinet differential type designed for easy gear to withstand a heavy load of new gear. Critical structural adjustment of high-voltage areas must be such as to reduce tensions. The basis for this optimization is the results of task solution by finite element method (FEM)

Machine Vision System Measuring the Trajectory of Upper Limb Motion Applying the Matlab Software

This paper discusses the problem of possibilities for applying a machine vision in the measurement of the trajectory of the upper limb movement in rehabilitation exercises. The fundamental presumption of designed system was to get the image from the camera’s CCD processor, possibilities of measuring and its processing. As a result of the application system, it is possible to dynamically determine the radius between the shoulder and forearm, and also the angle between the shoulder and the chest of the man, as function of the limb motion. The created system gives the possibility to use a non-invasive method of measurement, allows visualization and full analysis of the rehabilitation progress and also allows keeping electronic records of patients

Rectification of Gas Pipeline Bridging with the Support of Experimental Stress Analysis and Means of Regression and Correlation Analysis

The paper deals with the connection between the issue of rectification of the structural system and the corresponding experimental and related statistical analysis of stresses. The solution was demonstrated in the example of replacing the aboveground gas pipeline with an underground solution. During the implementation of landscaping for the underground solution, there was a risk of damage to the existing structure. Due to the specific problems in stress analysis based on strain gauge measurements, especially with regard to the narrow range of gas pressure as the primary input quantity, the obtained data had to be subjected to complex statistical procedures. Several linear and non-linear regression models were compiled and subjected to normality, homoscedasticity, and autocorrelation tests. The data obtained in this manner ruled out the possibility of limited state occurrence on the existing structure and, in conjunction with other information, enabled the successful completion of the rectification process to its current form. The scientific added value of the contribution should be the demonstration of procedure methodology and relatively unconventional use of regression and correlation analysis methods and means in the technical field for stress analysis in solving engineering practice problems

Influence of Different Strain Hardening Models on the Behavior of Materials in the Elastic–Plastic Regime under Cyclic Loading

In exact analyses of bodies in the elastic–plastic regime, the behavior of the material above critical stress values plays a key role. In addition, under cyclic stress, important phenomena to be taken into account are the various types of hardening and the design of the material or structure. In this process, it is important to define several groups of characteristics. These include, for instance, the initial area of plasticity or load which defines the interface between elastic and plastic deformation area. The characteristics also include the relevant law of plastic deformation which specifies the velocity direction of plastic deformation during plastic deformation. In the hardening condition, it is also important to determine the position, size and shape of the subsequent loading area. The elasto-plastic theory was used for the analysis of special compliant mechanisms that are applied for positioning of extremely precise members of the Compact Linear Collider (CLIC), e.g., cryomagnets, laser equipment, etc. Different types of deformation hardening were used to simulate the behavior of particular structural elements in the elastic–plastic regime. Obtained values of stresses and deformations may be used in further practical applications or as default values in other strain hardening model simulations

Modal Analysis Using Digital Image Correlation Technique

The present paper discusses a new approach for the experimental determination of modal parameters (resonant frequencies, modal shapes and damping coefficients) based on measured displacement values, using the non-contact optical method of digital image correlation (DIC). The output is a newly developed application module that, based on a three-dimensional displacement matrix from the experimental measurement results, can construct a frequency response function (FRF) for the purpose of experimental and operational modal analysis. From this frequency response function, the modal parameters of interest are able to be determined. The application module has been designed for practical use in Scilab 6.1.0, and its code interfaces directly with the ISTRA4D high-speed camera software. The module was built on measurements of a steel plate excited by an impact hammer to simulate experimental modal analysis. Verification of the correctness of the computational algorithm or the obtained modal parameters of the excited sheet metal plate was performed by simulation in the numerical software Abaqus, whose modal shapes and resonant frequencies showed high agreement with the results of the newly developed application