SV - JME 56 (2010) 7-8

---

Virtual User Interface for the Remote Control of a Nano-Robotic Cell Using a Haptic-Device

Corresponding author - Gregor Škorc

Authors - Simon Zapušek - Jure Čas - Riko Šafarič

Abstract

This paper describes the development of a virtual user interface for the remote control of a nano-robotic production cell. The user interface combines two different software applications, built on two different software platforms. The first-host application is based on a LabView 8.5 software package and runs on a real-time target. It is used as a communication interface between the nano-robotic cell and a remote user interface. The remote application was created within a Microsoft Visual C 6.0 software package using C++ programming language. It is used for the virtual remote control of a nano-robotic cell. Depending on production demands, the remote user can choose between two different control techniques. The first one is a classical input algorithm where the user sets any move trajectory of the nano-robotic cell directly through a remote user interface. Each axis separately or all axes together can be moved in this way. Another control option supports acquiring movement trajectory using a haptic-device. In this regime the user receives real-time force feedback information which makes remote control even more realistic. Both control regimes are supported by an animated, virtual, VRML model of the target application. This VRML model is used for off-line simulation or real-time monitoring of the target application movement. UDP protocol is used as a basic communication protocol between the host and remote applications.

Keywords - virtual remote control, nano-positioning, VRML, LabVIEW Real Time, MEMS assembly

Paper's information

Strojniški vestnik - Journal of Mechanical Engineering 56(2010)7-8, 423-435
UDC 621.398:004.8

 Virtual User Interface for the Remote Control of a Nano-Robotic Cell Using a Haptic-Device (pdf)

 

---

 

Analysis of the Sailplane Final Approaches Performed by Cosine-Law Speed Variations

Corresponding author - Zoran Stefanović

Authors - Ivan Kostić

Abstract

High lift-to-drag ratios of the contemporary sailplanes make them the most energy efficient flying vehicles. On the other hand, this capability may become their serious disadvantage during the landing, if their aerodynamic deceleration devices become inoperable in flight. Not being able to dissipate the excess energy quickly when close to the ground, they may fly over the available landing ground and finish up in front of the obstacles, with still too much energy to land and not enough to fly over them.
Beside the sideslipping flight in final, where energy is dissipated through the increased sideforce drag, another solution to this problem has been offered in a number of papers. By numerical analyses they have shown that landing distance in such cases could be minimized using rather complex oscillating flight paths in vertical plane. Although relevant distance reductions could be achieved through them, performing such paths in practice would require exceptional piloting skills. Instead of that, in this paper much simpler approach profiles have been analyzed, based on two types of cosine speed variations with constant periods and amplitudes, which could be flown by pilots of average flying experience. After establishing a quick convergence algorithm, numerical solutions for several typical cases, belonging to two general speed variation types, have been presented. The same initial and terminal reference energy states have been used. Although the distance reductions are smaller than obtained by distance-minimizing techniques, operational simplicity of presented techniques and some specific advantages prove them valuable within this category of problems.

Keywords - sailplane, final approach, inoperable spoilers, cosine speed variations

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 56(2010)7-8, 436-446
UDC 629.734.33:351.814.343

 Analysis of the Sailplane Final Approaches Performed by Cosine-Law Speed Variations (pdf)

---

An Investigation into the Influences of Grain Size and Grinding Parameters on Surface Roughness and Grinding Forces when Grinding

Corresponding author - Halil Demir

Authors - Abdulkadir Gullu – Ibrahim Ciftci – Ulvi Seker

Abstract

This study was carried out to investigate the effects of grain size on workpiece surface roughness and grinding forces when surface grinding AISI 1050 steel. A previously designed and constructed dynamometer was used to measure and record the forces developed during grinding. Grinding tests were carried out using different grinding wheels of different grains. Ground surface roughness measurements were also carried out. The results showed that grain size significantly affected the grinding forces and surface roughness values. Increasing grain size and depth of cut increased the grinding forces and surface roughness values. For different grain sizes, depth of cuts of 0.01 and 0.02 mm did not result in any significant variations in the grinding forces but further increase in depth of cut led to variations of up to 50% in grinding forces.

Keywords - surface grinding, grinding forces, surface roughness, grinding wheel, grain size

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 56(2010)7-8, 447-454
UDC 621.795:621.922.025

 An Investigation into the Influences of Grain Size and Grinding Parameters on Surface Roughness and Grinding Forces when Grinding (pdf)

 

---

 

Optimal Design of the Fuzzy Sliding Mode Control for a DC Servo Drive

Corresponding author - Dragan Antić
Authors - Marko Milojković – Zoran Jovanović – Saša Nikolić

Abstract

A new controller for the optimal speed control of a DC drive is presented in this paper. The controller employs a variant of fuzzy sliding mode, optimized by a genetic algorithm. Proposed controller has many advantages, such as satisfactory control performance under a wide range of operating conditions, a faster response than conventional controllers and suppressed chattering phenomenon. The simulations, experimental results, and comparative analysis verify the efficiency, excellent performance, and robustness of such a control in the case of a DC servomotor.

Keywords - sliding mode control, fuzzy control, genetic algorithm, DC motor

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 56(2010)7-8, 455-463
UDC 621.3:681.5:004.94

 Optimal Design of the Fuzzy Sliding Mode Control for a DC Servo Drive (pdf)

---

Flow Characteristics of Bladeless Impeller Made of Open Cell Porous Material

Corresponding author - Gašper Benedik

Authors - Brane Širok, Janez Rihtaršič, Marko Hočevar

Abstract

This article describes a bladeless turbo machine impeller that transfers energy from rotor to fluid over a structure of porous material. Impeller construction is described and theoretical description of fluid flow through rotating porous material is given. Pressure drops for impellers made of different materials and with different design parameters in dependence on air volume flow rate were measured. Measurements of local air flow velocity field close to impeller circumference were performed on a stationary impeller with one component hot-wire anemometer. Air flow velocity dependence on local material structure and volume flow rate was analysed. Integral characteristics measurements for different impellers made of different materials and with different design parameters are presented. Local measurements of local radial and tangential velocities close to rotating impeller circumference are shown.

Keywords - bladeless impeller, turbo machine, porous open cell material, velocity field, hot-wire anemometer

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 56(2010)7-8, 464-476
UDC 532.57:621.63

 Flow Characteristics of Bladeless Impeller Made of Open Cell Porous Material (pdf)

---

A Novel Double-Exposure Shadowgraph Method for Observation of Optodynamic Shock Waves Using Fiber-Optic Illumination

Corresponding author - Tadej Perhavec

Avtorji - Janez Diaci

Abstract

A novel double-exposure shadowgraph method is presented which allows visualization of an expanding shock wave in two time instances on a single image. The method has been developed to study shock waves generated in air during interaction of Er:YAG laser light with water and biological tissues. The shock wave is illuminated by pulsed green laser light coupled into two optical fibers of different lengths to establish two illumination flashes separated by a fixed time delay. An image of the shock wave region, acquired by a digital still camera, exhibits two well separated shock wavefronts. The optical set-up is analyzed using a paraxial ray model to explain the observed eccentricity of the two acquired wavefronts and provide guidelines for assembling the set-up.

Keywords - shadowgraph, laser ablation, shock propagation

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 56(2010)7-8, 477-482
UDC 681.7:534.222.2:004.94

 A Novel Double-Exposure Shadowgraph Method for Observation of Optodynamic Shock Waves Using Fiber-Optic Illumination (pdf)

 

---

 

The Application of a New Formula of Nakaoka Coefficient in HF Inductive Welding

Corresponding author - Miroslav S. Milićević

Abstract
The high-frequency welding procedure represents the complex theory which is possible to be used as an approximate calculation of important data such as current, voltage and the power of inductor and the welding object itself as well as the degree of usage. By applying so far known procedures, long and complex calculations are done through the use of the terms as well as many tables and graphic dependences. In this paper, a new analytical dependence is shown by the use of which the value of Nakaoka coefficient is being calculated through specific approximation, and by which important parameters and the range of high-frequency inductive welding of steel pipes are also calculated. By applying the results of this paper, the calculating procedure is shortened and made easier which makes way for optimizing the choice of thermal regime.

Keywords - numerical approximation, electromagnetic field, HF welding, equivalence scheme, Nakaoka coefficient, practical application

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 56(2010)7-8, 483-488
UDC 621.791.7:004.942

 The Application of a New Formula of Nakaoka Coefficient in HF Inductive Welding (pdf)

 

---

Statistical Analysis for Strategic Innovation Decisions in Slovenian Mechanical Industry

Corresponding author - Peter Fatur

Authors - Borut Likar

Abstract
The objective of this study is to identify the main factors influencing the innovation and R&D performance of the machinery and equipment manufacturing industry in the Republic of Slovenia (RS). The research is based on statistical data from the Statistical Office of RS. Spearman’s coefficient of correlation has been applied to the entire set of input and output variables in calculating the correlation coefficients. Results indicate the existence of two clusters of companies. Both are innovation followers but differ in their capabilities to produce breakthrough innovations and innovation-related turnover. For both of them, no correlation between the innovation outputs and business/financial performance is present.
Based on the empirical findings, we propose some organizational areas where additional managerial effort needs to be invested. Thus, the research also has a practical implication for the enterprises as well as for the national policy makers.

Keywords - innovation, R&D, technology, industrial management, productivity and performance management; machinery and equipment manufacturing industry

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 56(2010)7-8, 489-496
UDC 519.23:658.5:001.895

 Statistical Analysis for Strategic Innovation Decisions in Slovenian Mechanical Industry (pdf)

 

---

 
Characterization of the Dynamic Behaviour of a Basketball Goal Mounted on a Ceiling

Corresponding author - Matija Javorski

Authors - Primož Čermelj – Miha Boltežar

Abstract
An experimental modal analysis was performed on an existing basketball goal, with the modes, natural frequencies and damping ratios identified. On this basis, a numerical model was created, employing the finite-element method. Due to the correlation between the experimental and the numerical results, the model was accepted as valid. Subsequently, this model was used to analyse the transient response that occurs when a fully loaded goal suddenly becomes unloaded. The resulting oscillation was compared to the valid standard for this type of sports equipment.

Keywords - basketball, steel structures, finite element method, experimental modal analysis, oscillations

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 56(2010)7-8, 497-502
UDC 685.632:624.014.2:519.6

 Characterization of the Dynamic Behaviour of a Basketball Goal Mounted on a Ceiling (pdf)

 

---

 
Analytical Description of Polygonal Holes Boring - General Approach

Corresponding author - Miodrag Zlokolica

Authors - Maja Čavić - Milan Kostić

Abstract
Equilateral polygonal holes can be manufactured on conventional machines such as lathes or drills using special tool. Tool has to rotate about its axis while its center simultaneously follows complex planar trajectory. Tool center motion can be achieved in several ways: by guiding tool with template which shape exactly matches the shape of the hole produced, using cam or planetary gears mechanism etc.
To describe accurately polygonal hole boring process it is necessary to determine tool geometry, tool motion as well as realized hole geometry. In order to prescribe optimal boring regime time-history of tool cutting blade tip speed has to be obtained. Holes are, generally, produced with rounded corners so, having in mind further operations with work piece, it is important to know corner radius.
Analytical approach presented in this paper enables easy and efficient forming of the mathematical model describing geometry and kinematics of polygonal hole boring process.

Keywords - polygonal hole, boring, kinematics

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 56(2010)7-8, 503-512
UDC 531.1:621.95

 Analytical Description of Polygonal Holes Boring - General Approach (pdf)

 

---

The Role of the User and the Society in New Product Development

Corresponding author - Nusa Fain

Authors - Niels Moes - Jože Duhovnik

Abstract
Within the knowledge-based economy several institutions are involved in product innovation processes. Literature study has shown that the most researched and cited are the industry-university-government relations, presented in the Triple Helix model of institutional relations within new product development (NPD). Based on a case study of the Academic Virtual Enterprise, we have put the sole input of these institutions in NPD into question. We have tested and supported the claim that the user and the society are equal partners in the product innovation process. We have put forward the Fourfold Helix model that features a new formation of institutional relations where special focus is placed on the involvement of the user and the society in NPD.

Keywords - triple helix, user, society, market pull, technology push, fourfold helix, European Global Product Realization course

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 56(2010)7-8, 513-522
UDC 316.4:001.895

 The Role of the User and the Society in New Product Development (pdf)

 

---