Miroslav Dovica

In-pipe bristled micromachine

This paper deals with in-pipe micromachine, which moves in pipes with inner diameter under 25 mm. The micromachine locomotion principle is based directional friction force between bristle tip and pipe wall. At first we have theoretically analysed the locomotion principle. The next part consist of analysis of bristle tip connection with inner pipe wall. Finally, the analysis is supported with experiments.

Snake Robot Movement in the Pipe Using Concertina Locomotion

Inspection tasks of pipes or channels are part of the engineering practice. In the past there were investigated conventional approaches like wheeled-based mechanisms. This paper deals with unconventional approach - snake robot moving in the pipe. In the paper locomotion pattern of concertina is introduced and subsequently kinematic model of concertina locomotion is established. Main requirements and conditions of presented locomotion pattern are stated. Using software Matlab the kinematic model is simulated according designed locomotion pattern in order to verify the kinematic model. For experimental purposes the experimental snake robot – LocoSnake is used. Simulation and experiment are compared and evaluated.

Failure analysis of conveyor belt samples under tensile load

This paper is dedicated to investigating the properties of smooth conveyor belts through a tensile loading test, with the aim of examining the behavior of the inner structure of the belt samples. When the belt is subjected to a long-term strain, the belt relaxation effect is observed and changes may occur to the inner structure of the belt. The tensile test at constant velocity determines the load strength limit of the strip samples. The experiment has also shown the phenomenon of relaxation of the samples after the load. Metro-tomographic analysis is used to observe the behavior of the internal structure of the belt sample after the load. The obtained results indicate the initial damage of the inner structure of the conveyor belt occurred at the value of 2157 N. Under this load, the maximum damage size was 4.8 mm. This confirms the suitability of the method for tracking changes in the internal structure.

Analysis of defects in carcass of rubber–textile conveyor belts using metrotomography:

Rubber–textile construction of conveyor belts is widely used in various continuous transport systems. Due to the fact that complex carcass is vulcanised, its observation and analysis are very difficult to perform. The methods used so far have been based on its violent extracting, often accompanied with the formation and existence of defects. Such an analysis does not allow distinguishing between defects caused by operation of the belt or defects caused by the process of extracting itself. This paper aims to verify a new approach to examining the inner carcass of rubber–textile conveyor belts with a focus on the possibility to obtain information about its condition. This has not been possible with the methods used so far. The main focus is on the measurement of distance between the individual fibres in the warp and weft of the carcass, and simple size analysis of the identified defects. Presented results prove that the method of industrial tomography clearly identifies the defects in the conveyor belt carcass. The method enables the identification of single fibres, punctures and separation of individual layers.

Influences of Surface Determination for Measurements Obtained by Industrial Computed Tomography

At present emphasis is placed on input or output control of products in the manufacturing process. One of the criteria is the dimensional analysis or porosity analysis of products. In the case that products are of complicated shapes, or measurements are to be taken in places which are not accessible to standard measuring devices (manual measurements, coordinate measuring machines) the use of computed tomography is one of the possibilities for obtaining the desired dimensions. These technologies work with digital data and therefore the surfaces which are to be assessed must be created on the basis of determined criteria. Surface determination is one of the most important settings during the evaluation of the visual shape (state) of a surface and assessing dimensions. During such evaluation this is the main parameter which globally influences the precision of the obtained data. In the case of an unsuitably determined surface the obtained results can vary from reality even by several tenths of a millimeter depending on the scanned object and the scanning conditions. The conveyor belts are composed of two or more materials with different densities, such as rubber and textile fibers. In cooperation with Faculty of Mining, Ecology, Process Control and Geotechnology is tested and evaluated the effect of the impactor with various energy into conveyor belt. The correct surface determination for selected material is necessary to evaluate the dimensions, the damage and pores. The article deals with the impact of surface determination on the result of a measurement.

In-pipe Minimachine and Principles of its Motion and Control

In-pipe Minimachine and Principles of its Motion and Control The paper deals with the minimachine designed to move within the pipes with inner diameter less than 25 mm. The minimachine consists of two modules connected by a link of variable length enabling to change their mutual distance. Motion is based on inchworm principle known from biology. In motion sequence one of the modules is anchored to the inner surface of the pipe, while the second is released and moved forward by change of the link length. The principle of the link length change consists in transformation of the actuator rotary movement to the linear motion. Problem of anchoring the modules by flexible metal bristles is analyzed in the paper.

The Effectiveness of a Three-Temperature Heat Pump System

Three-temperature heating systems consist of a heat engine and a heat pump, enabling thus maximum usage of the primary thermal source for the heating of buildings. This analysis has revealed obvious advantages and disadvantages that the combining of thermodynamic systems has in future development, also with respect to environmental and economic issues. It appears that the combination of a Stirling engine or a similar heat drive with a heat pump is especially suitable. In order to analyze the effectiveness of such a system, a comprehensive calculation procedure is used: its basis lies in accounting for all types of energy and their relationship to the original natural resource. The present paper aims to point out that the combination of Stirling engine and a heat pump is a useful solution thanks to the most favorable resultant economic impact if compared to the usage of a diesel, four-stroke gas, or, most commonly used, electric drive.

Condition Evaluation of Optical Position Sensor

Paper deals with experimental identification of condition of optical position sensor. Optical sensor can be sensitive to reflection surface on measured object. Measurement uncertainty is also evaluated.

Verifying the prediction result reliability using k-ε, eddy dissipation, and discrete transfer models applied on methane combustion using a prototype low-pressure burner

The article aims to verify the accuracy of a method to simulate the combustion chamber with a low-pressure prototype burner equipped with a specific “mixing element” and air baffle. The burner has an output of 4 kW and combusts methane. In detail, the article evaluates the accuracy of the final courses of temperatures and CO concentrations in the combustion chamber, which were obtained having combined the mathematical models k-ε, Eddy Dissipation and Discrete Transfer. CFD software CFX was used for the solution and visualisation of the results. The verification measurements imply that the final course of temperature plotted on the vertical axis of the combustion chamber differs from the real course by +21.7% on average. The predicted CO concentrations are relatively satisfactory in the chamber locations with lower temperatures – at the combustion chamber outlet the deviation from the measured value was +31.8%. Overall, the applied method may be considered acceptable to simulate the thermal field in a combustion chamber with the described burner.

Elimination of Thermal Drift in Measuring the Positioning Accuracy of a Three Axis Milling Machine

The aim of this paper is to draw attention to more reliable verification method of positioning accuracy. The improvement lies in mathematical elimination of thermal impact during the measurement process. This thermal impact, always present during the motion of movable parts, is of a special systemic character. It increases the indefiniteness of measurement of the classic measurement method. This measurement uncertainty can be reduced by implementing the procedure introduced in this paper. The reduction can be achieved by separating the temperature impact from other sources of inaccuracy. Such separation is a very new solution. The methodology relies on mathematical processing and does not depend on the manner of accuracy measurement. The evaluation method also yields diagnostic information on the machine’s condition. The experiments were performed with the use of laser interferometer.