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Changes of the human gait after total hip joint replacement surgery
Get PDFThe aim of this work was to determine the effect of a hip joint replacement on human locomotion-support apparatus and movement functions. 3D biomechanical model of human locomotion-support system was developed for comparative analysis of the healthy state and the state after total hip replacement operation. The effect of shift of hip joint replacement centre position on human movement and muscles activity patterns was determined by using computational and experimental methods. The results of analysis obtained on the basis of this model and method are presented: it is shown that the change of position of hip joint replacement elements (cup and sphere) has substantial effect on human walking patter
Investigation of vibrations of a tape in the printing device
Get PDFStability and controllability of a welding arc have a large influence on both the weld quality and welding productivity in the process of welding. Metal fusing and weld forming depend on the forces affecting the arc. Welding current creates electromagnetic forces, which basically define the influence of arc forces on molten metal. While estimating the magnitude of the influence of electromagnetic forces, it is necessary to investigate the radial distribution of arc pressure on the surface of a weld pool and take into account the dependence of distribution of electromagnetic forces on the non-consumable electrode tip geometry
The suboptimal set of parameters describing human gait
Get PDFThe influence of choosing a set of parameters describing human gait for automatic gait analysis and assessment has been presented in this paper. The investigations were based on three sets of parameters and two different classificators. The conclusion is that the best set of parameters is set of coefficients which have been obtained by modelling of human gait by means of identification using the regression functio
ERF valves controlled by plane capacitor electric field
Get PDFHoles filled with electrorheological fluid (ERF) are used to form the Braille symbols or relief in Array Manipulators. Matrix of holes is made in the fabric-based copper laminate. Voltage applied to coppered upper and lower surfaces of the plate creates electric field, which controls ERF viscosity. Three methods to form a relief are investigated: (a) using an elastic membrane, covering the holes, (b) dielectric pins moving in the holes, (c) metallic pins moving in the holes. Electric field in a hole of the matrix was calculated as electric field in a hole of plane capacitor. In the case of metallic pins, the mean electric field near the electrodes is considerably stronger than in the case of dielectric pins. The controlling voltage can be decreased using multilayer copper laminate valves, composed of some fabric-based plates with opposite directions of electric field in neighbouring plate
Determination of rational sizes of leg prosthetics manufacturing errors and their links resilience
Get PDFPaper presents rational values of manufacturing and assembly summary errors appointed according to hip and its joint, knee and tarsus motion trajectories, angular analysis, also research results of step asymmetry and variation of shoulder’s and head’s tilt angles, either the anthropometrical parameters were evaluated. The analysis of possibilities of manufacture and assembly errors and inter-compensation of leg prosthesis elastic links was made. The results showed that disabled person gait will be smoother and he will not get tired so soon, when values of elastic deformations will be two times bigger than the summary value of manufacturing and assembly errors. Besides, the essential condition of disabled smooth gait is that the value of manufacturing and assembly errors of leg prosthesis links would be positiv
Research into the heart rate and blood pressure dependence on loading and time
Get PDFThe article deals with the dependence of the effect of physical load on male and female heart rate and blood pressure on the step and constant load with a change in time. It has been established that with the load applied to different male and female age groups and its time increasing, the heart rate and blood pressure increases in terms of non-linear dependence. Characteristic points have been determined to exist in the functional dependence of the heart rate and blood pressure on the time of loading, in which the derivative value of the function is equal to zero. The human fatigue criterion has been established on the basis of the derivative of this characteristic point, which shows the individual’s reserve of the working capacity and its duratio
Study of robot actuator operating as a system on air films
Get PDFThe paper analyzes the dynamics of a robot pneumatic actuator. The mechanical system motion is described by a differential equation system when the air flow is expressed by a non-dimensional Prandtl formula. The findings of the digital study are presented. The zones of self-exciting vibrations of the vibrotransducer have been determined, as well as the dependences of amplitudes and frequency upon the supply air pressure. The dependence of the linear movement of the actuator’s gripper device and its velocity on the geometric parameters of the vibrating transducer of the mechanical system is presente
Finite element analysis of thermo-elastical modal damping of mems vibrations
Get PDFThe paper deals with finite element analysis of damped modal vibrations Q-factor values determined by thermal-elastic damping in micro-electrical-mechanical systems (MEMS). Mathematically the problem is formulated as a complex eigenvalue problem. Verification problems have been solved by using several computational environments and different presentations of model equations in order to comprehend and reduce the influence of rounding errors. The analysis of damped modal properties of selected real MEMS resonator revealed the main features of thermal-elastic damping by taking into account 3D geometry of the resonator and anchoring (clamping) structur
Fiber-optic sensors for nanometric displacement and vibration measurement in mechatronics
Get PDFFiber-optic sensors are widely used for displacement and vibration measurements in mechatronic systems. Sensors can be of very small size and operate in blast danger conditions and strong electromagnetic interference environment. In this work modeling and experimental investigation of the characteristics U-h of fiber-optic sensor of displacement have been accomplished with a view to obtain the maximal sensitivity in the displacement and vibration measurements. The modeling and experimental results were perfectly coincidental, therefore the limit sensitivity of sensors can be predicted by modeling. Configurations of non-contact fiber optic sensors of the maximal possible sensitivity have been found, the metrological parameters of which do not depend either on the degradation of the light source, intensity or on the elements used in the mechatronics system measurements as well as on the value of the mirror reflection coefficient and changes with the aging process. All that increases the reliability of mechatronics system monitoring, which is of utmost importance for their exploitatio
Analysis of insertion process for robotic assembly
Get PDFInsertion process of cylindrical parts with clearance for robotic assembly using vibratory excitation is analyzed in the paper. Mathematical model of vibratory parts insertion process, which determines peg contact with the chamfer of the bush, peg one point and two point contact with the bush hole, was formed. Simulation of cylindrical parts insertion process was performed. The influence of vibrations on the insertion process, when mobile based peg is kinematically excited in axial direction, was determined. The combinations of excitation and system parameters, under which insertion process duration is the shortest and the process is the most reliable, were detecte