Previous Issue

Table of Contents

Machines, Volume 7, Issue 2 (June 2019)

  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Readerexternal link to open them.
View options order results:
result details:
Displaying articles 1-27
Export citation of selected articles as:
Open AccessArticle
Modeling of Material Removal Rate and Surface Roughness Generated during Electro-Discharge Machining
Received: 4 May 2019 / Revised: 28 May 2019 / Accepted: 5 June 2019 / Published: 20 June 2019
Viewed by 76 | PDF Full-text (3144 KB) | HTML Full-text | XML Full-text
Abstract
This study reports on the numerical model development for the prediction of the material removal rate and surface roughness generated during electrical discharge machining (EDM). A simplified 2D numerical heat conduction equation along with additional assumptions, such as heat effect from previously generated [...] Read more.
This study reports on the numerical model development for the prediction of the material removal rate and surface roughness generated during electrical discharge machining (EDM). A simplified 2D numerical heat conduction equation along with additional assumptions, such as heat effect from previously generated crater on a subsequent crater and instantaneous evaporation of the workpiece, are considered. For the material removal rate, an axisymmetric rectangular domain was utilized, while for the surface roughness, a rectangular domain where every discharge resides at the end of previous crater was considered. Simulated results obtained by solving the heat equation based on a finite element scheme suggested that results are more realistic by considering instantaneous evaporation of the material from the workpiece and the effect of residual heat generated from each spark. Good agreement between our model and previously published data validated the newly proposed models and demonstrate that instantaneous evaporation, as well as residual heat, provide more realistic predictions of the EDM process. Full article
Figures

Figure 1

Open AccessArticle
Vibration-Based Experimental Identification of the Elastic Moduli Using Plate Specimens of the Olive Tree
Received: 31 March 2019 / Revised: 12 June 2019 / Accepted: 13 June 2019 / Published: 20 June 2019
Viewed by 66 | PDF Full-text (2917 KB) | HTML Full-text | XML Full-text
Abstract
Mechanical parameters of the olive wood plate have been computed by data inversion of vibrational experimental tests. A numerical-experimental method has allowed the evaluation of the two transverse shear moduli and the four in-plane moduli of a thick orthotropic olive tree plate. Therefore, [...] Read more.
Mechanical parameters of the olive wood plate have been computed by data inversion of vibrational experimental tests. A numerical-experimental method has allowed the evaluation of the two transverse shear moduli and the four in-plane moduli of a thick orthotropic olive tree plate. Therefore, the natural flexural vibration frequencies of olive trees plates have been evaluated by the impulse technique. For our purposes, we define the objective function as the difference between the numerical computation data and the experimental ones. The Levenberg–Marquardt algorithm was chosen as optimization strategy in order to minimize the matching error: the evaluation of the objective function has required a complete finite element simulation by using the ANSYS code. As input, we have used the uniaxial test data results obtained from the olive plates. The converged elastic moduli with n = 10 natural modes were E1 = 14.8 GPa, E2 = 1.04 GPa, G12 = 4.45 GPa, G23 = 4.02 GPa, G13 = 4.75 GPa, ν12 = 0.42, and ν13 = 0.42. The relative root mean square (RMS) errors between the experimental frequencies and the computed one is 9.40%. Then, it has been possible to obtain a good agreement between the measured and calculated frequencies. Therefore, it has been found that for plates of moderate thickness the reliability of the estimated values of the transverse shear moduli is good. Full article
Figures

Figure 1

Open AccessArticle
Experimental Characterization of the Coupling Stage of a Two-Stage Planetary Gearbox in Variable Operational Conditions
Received: 16 April 2019 / Revised: 5 June 2019 / Accepted: 17 June 2019 / Published: 20 June 2019
Viewed by 64 | PDF Full-text (3329 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents an experimental characterization of a two-stage planetary gearbox (TSPG) designed at the Laboratory of Robot Mechatronics (LARM2) in the University of Rome Tor Vergata. The TSPG operates differentially as function of the attached load and the internal friction forces caused [...] Read more.
This paper presents an experimental characterization of a two-stage planetary gearbox (TSPG) designed at the Laboratory of Robot Mechatronics (LARM2) in the University of Rome Tor Vergata. The TSPG operates differentially as function of the attached load and the internal friction forces caused for the contact between gears. Experiments under varying load conditions are developed in order to analyze the usefulness of the gearbox to avoid excessive torques on its internal elements. The analysis of the dynamic torques is presented as an indicator of stability in the gearbox operation. The results show that the actuation of the second operation stage reduces the torques 57% in the output shaft and 65% in the input shaft. The efficiency of the gearbox is estimated as 40% in presence of high internal friction forces. Full article
(This article belongs to the Special Issue Advances of Italian Machine Design)
Figures

Figure 1

Open AccessArticle
A New Stiffness Performance Index: Volumetric Isotropy Index
Received: 8 April 2019 / Revised: 10 June 2019 / Accepted: 17 June 2019 / Published: 18 June 2019
Viewed by 150 | PDF Full-text (4913 KB) | HTML Full-text | XML Full-text
Abstract
A new index for a precise calculation of a manipulator’s stiffness isotropy is introduced. The proposed index is compared with the conventionally used stiffness isotropy index by making use of the investigation on R-CUBE manipulator. The proposed index is shown to produce relatively [...] Read more.
A new index for a precise calculation of a manipulator’s stiffness isotropy is introduced. The proposed index is compared with the conventionally used stiffness isotropy index by making use of the investigation on R-CUBE manipulator. The proposed index is shown to produce relatively more precise results from which a higher number of isotropic poses are detected. Full article
(This article belongs to the Special Issue Advances of Italian Machine Design)
Figures

Figure 1

Open AccessArticle
Nonlinear Response of Tilting Pad Journal Bearings to Harmonic Excitation
Received: 19 April 2019 / Revised: 25 May 2019 / Accepted: 14 June 2019 / Published: 17 June 2019
Viewed by 152 | PDF Full-text (5495 KB) | HTML Full-text | XML Full-text
Abstract
In the experimental identification of dynamic bearing coefficients, usually small perturbations around the static equilibrium position are assumed and linear coefficients are considered. In the literature, studies on non-linear effects in plain journal bearings, especially from a numerical point of view, are reported. [...] Read more.
In the experimental identification of dynamic bearing coefficients, usually small perturbations around the static equilibrium position are assumed and linear coefficients are considered. In the literature, studies on non-linear effects in plain journal bearings, especially from a numerical point of view, are reported. Few similar studies can be found on tilting pad journal bearings (TPJB). The present work reports some peculiar aspects observed during the experimental identification procedure of TPJB linear dynamic coefficients. The tests are performed on a test bench designed for large size journal bearings operating at high peripheral speeds and static loads. A quasi-static procedure is developed to quickly check the results obtained from the usually adopted dynamic excitation. It consists of applying a slowly rotating force to the floating stator and measuring the relative displacement of the stator from the rotating shaft. Different levels of static and dynamic load are applied to two different TPJBs with four and five pads. Deformed orbits have been observed increasing the ratio between dynamic load and static load, suggesting the presence of non-linearity. Similar results are obtained with simple analytical models assuming suitably tuned non-linear stiffness terms. Full article
(This article belongs to the Special Issue Advances of Italian Machine Design)
Figures

Figure 1

Open AccessArticle
Unmanned Ground Vehicle Modelling in Gazebo/ROS-Based Environments
Received: 31 March 2019 / Revised: 5 June 2019 / Accepted: 9 June 2019 / Published: 14 June 2019
Viewed by 151 | PDF Full-text (1621 KB)
Abstract
The fusion of different technologies is the base of the fourth industrial revolution. Companies are encouraged to integrate new tools in their production processes in order to improve working conditions and increase productivity and production quality. The integration between information, communication technologies and [...] Read more.
The fusion of different technologies is the base of the fourth industrial revolution. Companies are encouraged to integrate new tools in their production processes in order to improve working conditions and increase productivity and production quality. The integration between information, communication technologies and industrial automation can create highly flexible production models for products and services that can be customized through real-time interactions between consumer, production and machinery throughout the production process. The future of production, therefore, depends on increasingly intelligent machinery through the use of digital systems. The key elements for future integrated devices are intelligent systems and machines, based on human–machine interaction and information sharing. To do so, the implementation of shared languages that allow different systems to dialogue in a simple way is necessary. In this perspective, the use of advanced prototyping tools like Open-Source programming systems, the development of more detailed multibody models through the use of CAD software and the use of self-learning techniques will allow for developing a new class of machines capable of revolutionizing our companies. The purpose of this paper is to present a waypoint navigation activity of a custom Wheeled Mobile Robot (WMR) in an available simulated 3D indoor environment by using the Gazebo simulator. Gazebo was developed in 2002 at the University of Southern California. The idea was to create a high-fidelity simulator that gave the possibility to simulate robots in outdoor environments under various conditions. In particular, we wanted to test the high-performance physics Open Dynamics Engine (ODE) and the sensors feature present in Gazebo for prototype development activities. This choice was made for the possibility of emulating not only the system under analysis, but also the world in which the robot will operate. Furthermore, the integration tools available with Solidworks and Matlab-Simulink, well known commercial platforms of modelling and robotics control respectively, are also explored. Full article
Open AccessArticle
Wind Turbine Yaw Control Optimization and Its Impact on Performance
Received: 28 March 2019 / Revised: 10 June 2019 / Accepted: 10 June 2019 / Published: 11 June 2019
Viewed by 181 | PDF Full-text (4147 KB) | HTML Full-text | XML Full-text
Abstract
The optimization of wind energy conversion efficiency has been recently boosting the technology improvement and the scientific comprehension of wind turbines. In this context, the yawing behavior of wind turbines has become a key topic: the yaw control can actually be exploited for [...] Read more.
The optimization of wind energy conversion efficiency has been recently boosting the technology improvement and the scientific comprehension of wind turbines. In this context, the yawing behavior of wind turbines has become a key topic: the yaw control can actually be exploited for optimization at the level of single wind turbine and of wind farm (for example, through active control of wakes). On these grounds, this work is devoted to the study of the yaw control optimization on a 2 MW wind turbine. The upgrade is estimated by analysing the difference between the measured post-upgrade power and a data driven model of the power according to the pre-upgrade behavior. Particular attention has therefore been devoted to the formulation of a reliable model for the pre-upgrade power of the wind turbine of interest, as a function of the operation variables of all the nearby wind turbines in the wind farm: the high correlation between the possible covariates of the model indicates that Principal Component Regression (PCR) is an adequate choice. Using this method, the obtained result for the selected test case is that the yaw control optimization provides a 1% of annual energy production improvement. This result indicates that wind turbine control optimization can non-negligibly improve the efficiency of wind turbine technology. Full article
Figures

Figure 1

Open AccessArticle
Flexible Fingers Based on Shape Memory Alloy Actuated Modules
Received: 9 May 2019 / Revised: 6 June 2019 / Accepted: 7 June 2019 / Published: 10 June 2019
Viewed by 155 | PDF Full-text (1320 KB)
Abstract
To meet the needs of present-day robotics, a family of gripping flexible fingers has been designed. Each of them consists of a number of independent and flexible modules that can be assembled in different configurations. Each module consists of a body with a [...] Read more.
To meet the needs of present-day robotics, a family of gripping flexible fingers has been designed. Each of them consists of a number of independent and flexible modules that can be assembled in different configurations. Each module consists of a body with a flexible central rod and three longitudinally positioned shape memory alloy (SMA) wires. When heated by the Joule effect, one to two SMA wires shorten, allowing the module to bend. The return to undeformed conditions is achieved in calm air and is guaranteed by the elastic bias force exerted by the central rod. This article presents the basic concept of the module and a simple mathematical model for the design of the device. Experimental tests were carried out on three prototypes with bodies made of different materials. The results of these tests confirm the need to reduce the antagonistic action of the inactive SMA wires and led to the realization of a fourth prototype equipped with an additional SMA wire-driven locking/unlocking device for these wires. The preliminary results of this last prototype are encouraging. Full article
(This article belongs to the Special Issue Advances of Italian Machine Design)
Open AccessArticle
Twin-Shaft Mixers’ Mechanical Behavior Numerical Simulations of the Mix and Phases
Received: 27 March 2019 / Revised: 3 June 2019 / Accepted: 5 June 2019 / Published: 7 June 2019
Viewed by 182 | PDF Full-text (1605 KB)
Abstract
In this paper, the mechanical behavior of concrete twin-shaft mixers is analyzed in terms of power consumption and exchanged forces between the mixture and the mixing organs during the mixing cycle. The mixing cycle is divided into two macro phases, named transient and [...] Read more.
In this paper, the mechanical behavior of concrete twin-shaft mixers is analyzed in terms of power consumption and exchanged forces between the mixture and the mixing organs during the mixing cycle. The mixing cycle is divided into two macro phases, named transient and regime phase, where the behavior of the mixture is modeled in two different ways. A force estimation and power consumption prediction model are presented for both the studied phases and they are validated by experimental campaigns. From the application of this model to different machines and by varying different design parameters, the optimization of the power consumption of the concrete twin-shaft mixers is analyzed. Results of this work can be used to increase productivity and profitability of concrete mixers and reduce energy waste in the industries which involve mixing processes. Full article
Figures

Graphical abstract

Open AccessArticle
Design and Prototyping of Miniaturized Straight Bevel Gears for Biomedical Applications
Received: 8 May 2019 / Revised: 29 May 2019 / Accepted: 31 May 2019 / Published: 4 June 2019
Viewed by 270 | PDF Full-text (4709 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a semi-automated design algorithm for computing straight bevel gear involute profiles. The proposed formulation is based on the Tredgold approximation method. It allows the design of a pair of bevel gears with any desired number of teeth and relative axes [...] Read more.
This paper presents a semi-automated design algorithm for computing straight bevel gear involute profiles. The proposed formulation is based on the Tredgold approximation method. It allows the design of a pair of bevel gears with any desired number of teeth and relative axes inclination angles by implementing additive manufacturing technology. A specific case study is discussed to calculate the profiles of two straight bevel gears of a biomedical application. Namely, this paper illustrates the design of the bevel gears for a new laparoscopic robotic system, EasyLap, under development with a grant from POR Calabria 2014–2020 Fesr-Fse. A meshing analysis is carried out to identify potential design errors. Moreover, finite element-based tooth contact analysis is fulfilled for determining the vibrational performances of the conjugate tooth profiles throughout a whole meshing cycle. Simulation results and a built prototype are reported to show the engineering feasibility and effectiveness of the proposed design approach. Full article
(This article belongs to the Special Issue Advances of Italian Machine Design)
Figures

Figure 1

Open AccessArticle
Description and In-Vitro Test Results of a New Wearable/Portable Device for Extracorporeal Blood Ultrafiltration
Received: 15 April 2019 / Revised: 29 May 2019 / Accepted: 31 May 2019 / Published: 4 June 2019
Viewed by 185 | PDF Full-text (4389 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents the design of Rene Artificiale Portatile (RAP), a novel wearable and portable device for extracorporeal blood ultrafiltration, capable of providing remote treatment of fluid overload in patients with kidney diseases and/or congestive heart failure. The development of the device is [...] Read more.
This paper presents the design of Rene Artificiale Portatile (RAP), a novel wearable and portable device for extracorporeal blood ultrafiltration, capable of providing remote treatment of fluid overload in patients with kidney diseases and/or congestive heart failure. The development of the device is based on a new design paradigm, since the layout of the device is box-shaped, as to fit a backpack or a trolley case, differentiating it from other existing devices. The efficient layout and component placement guarantee minimalization and ergonomics, as well as an efficient and cost-effective use. The redundant control architecture of the device has been implemented to ensure a high level of safety and an effective implementation of the clinical treatment. The consistency of the design and its effective implementation are assessed by the results of the preliminary in-vitro tests presented and discussed in this work. Full article
(This article belongs to the Special Issue Advances of Italian Machine Design)
Figures

Figure 1

Open AccessArticle
Investigation on the Mechanical Properties of MRE Compounds
Received: 6 March 2019 / Revised: 23 May 2019 / Accepted: 24 May 2019 / Published: 1 June 2019
Viewed by 186 | PDF Full-text (5196 KB) | HTML Full-text | XML Full-text
Abstract
This paper describes an experimental investigation conducted on magneto-rheological elastomers (MREs) with the aim of adopting these materials to make mounts to be used as vibration isolators. These materials, consisting of an elastomeric matrix containing ferromagnetic particles, are considered to be smart materials, [...] Read more.
This paper describes an experimental investigation conducted on magneto-rheological elastomers (MREs) with the aim of adopting these materials to make mounts to be used as vibration isolators. These materials, consisting of an elastomeric matrix containing ferromagnetic particles, are considered to be smart materials, as it is possible to control their mechanical properties by means of an applied magnetic field. In the first part of the paper, the criteria adopted to define the characteristics of the material and the experimental procedures for making samples are described. The samples are subjected to a compressive static test and are then, adopting a testing machine specially configured, tested for shear periodic loads, each characterized by a different constant compressive preload. The testing machine is equipped with a coil, with which it is possible to vary the intensity of the magnetic field crossing the sample during testing to evaluate the magneto-rheological effect on the materials’ characteristics in terms of stiffness and damping. Full article
(This article belongs to the Special Issue Advances of Italian Machine Design)
Figures

Figure 1

Open AccessArticle
Experimental Vibration Analysis of a Small Scale Vertical Wind Energy System for Residential Use
Received: 19 April 2019 / Revised: 8 May 2019 / Accepted: 20 May 2019 / Published: 22 May 2019
Viewed by 243 | PDF Full-text (3899 KB) | HTML Full-text | XML Full-text
Abstract
In the recent years, distributed energy production has been one of the main research topics about renewable energies. The decentralization of electric production from wind resources raises the issues of reducing the size of generators, from the MW scale of industrial wind farm [...] Read more.
In the recent years, distributed energy production has been one of the main research topics about renewable energies. The decentralization of electric production from wind resources raises the issues of reducing the size of generators, from the MW scale of industrial wind farm turbines to the kW scale, and possibly employing them in urban areas, where the wind flow is complex and extremely turbulent because of the presence of buildings and obstacles. On these grounds, the use of small-scale vertical axis small wind turbines (VASWT) is a valid choice for on-site generation (OSG), considering their low sensitivity with respect to turbulent flow and that there is no need to align the turbine with wind direction, as occurs with horizontal axis small wind turbines (HASWT). In addition, VASWTs have a minor acoustic impact with respect to HASWTs. The aim of this paper is to study the interactions that take place between a 1.2 kW, vertical axis, Darrieus VASWT turbine and a small, experimental building, in order to analyze the noise and the vibrations transmitted to the structure. One method to damp the vibrations is then assessed through spectral analysis of data acquired through accelerometers located both in the mast of the wind turbine and at the building walls. The results confirm the usefulness of dampers to increase the building comfort regarding vibrations. Full article
Figures

Figure 1

Open AccessArticle
Impacts of Responsive Loads and Energy Storage System on Frequency Response of a Multi-Machine Power System
Received: 27 February 2019 / Revised: 17 May 2019 / Accepted: 17 May 2019 / Published: 21 May 2019
Viewed by 209 | PDF Full-text (6136 KB) | HTML Full-text | XML Full-text
Abstract
In recent decades, the power grid’s configuration is shifting towards a smart grid where responsive loads and energy storage systems (ESS) are finding an increased role in the power system operation. In the presented work, a mathematical formulation for frequency response analysis of [...] Read more.
In recent decades, the power grid’s configuration is shifting towards a smart grid where responsive loads and energy storage systems (ESS) are finding an increased role in the power system operation. In the presented work, a mathematical formulation for frequency response analysis of a multi-machine power system is developed, considering the individual and combined roles of ESS and responsive loads. The validity of the developed model is demonstrated with the help of multiple case studies, which consider the various configurations of the power system. Moreover, different combinations of capacities of generation units, ESS and responsive loads are also simulated. With the help of mathematical model and simulation results, it is demonstrated that ESS and responsive loads may improve the economy and performance of the power system even during the failure of a certain portion of generation capacity. Though the case studies consider non-reheat turbines only, the mathematical model and conclusions are equally valid for other types of turbines as well. Full article
Figures

Figure 1

Open AccessArticle
Planetary Mill with Friction Wheels Transmission Aided by an Additional Degree of Freedom
Received: 3 April 2019 / Revised: 16 May 2019 / Accepted: 17 May 2019 / Published: 21 May 2019
Viewed by 199 | PDF Full-text (5487 KB) | HTML Full-text | XML Full-text
Abstract
Processing in planetary ball mills is well suited to a large number of applications because they are easy to operate and versatile, grinding faster than other mills. Research related to planetary mills are mainly about the process evaluation, and there are few studies [...] Read more.
Processing in planetary ball mills is well suited to a large number of applications because they are easy to operate and versatile, grinding faster than other mills. Research related to planetary mills are mainly about the process evaluation, and there are few studies on the mechanical design of such equipment. This paper describes the decision process in the design of an innovative planetary mill in which design for manufacture and assembly (DFMA) principles were used to provide compact equipment made of simple and standardized parts. We developed a friction wheel mechanism with an additional degree of freedom that improves transmission and facilitates assembly, reducing the need for adjustment. It can be applied to different equipment that relies on planetary motion or rotating devices. A prototype was built, and its grinding performance surpasses that of other types of traditional mill. The mean particle size of alumina powder was reduced from 4.2 µm to 0.9 µm in 60 minutes. Full article
Figures

Figure 1

Open AccessArticle
Functional Analysis of Piedmont (Italy) Ancient Water Mills Aimed at Their Recovery or Reconversion
Received: 10 April 2019 / Revised: 9 May 2019 / Accepted: 10 May 2019 / Published: 13 May 2019
Viewed by 266 | PDF Full-text (18498 KB) | HTML Full-text | XML Full-text
Abstract
Since ancient times and for hundreds of years, grain mills, hammers, sawmills, spinning mills, and hemp rollers have been powered by water wheels. In the nineteenth century there were hundreds of thousands of mills in all of Europe. It is an enormous historical [...] Read more.
Since ancient times and for hundreds of years, grain mills, hammers, sawmills, spinning mills, and hemp rollers have been powered by water wheels. In the nineteenth century there were hundreds of thousands of mills in all of Europe. It is an enormous historical and cultural heritage of inestimable value, which is for the most part, abandoned today. Recently, there is a renewed interest in their reuse, both for their widespread diffusion in the territory and for the excellent environmental integration and intrinsic sustainability. Even when, for economic reasons, their recovery for the original tasks is not suitable, the conversion into mini plants for the production of electricity can be advantageous. In the paper, analyzing some typical examples of the old water mill of the Piemonte region, in North-West of Italy, the mechanical architecture of old water mill, from water wheels to millstones, is described and the functional details of various mechanisms are provided. In fact, by knowing only the specifics of the ancient mills, it is possible to enhance their potential and restore them from the perspective of a renewed high quality production, or reconvert them in mini-plants for the production of electricity. Full article
(This article belongs to the Special Issue Advances of Italian Machine Design)
Figures

Figure 1

Open AccessArticle
The Design of a New Manual Wheelchair for Sport
Received: 28 February 2019 / Revised: 4 May 2019 / Accepted: 6 May 2019 / Published: 9 May 2019
Viewed by 243 | PDF Full-text (7442 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, an innovative system of propulsion inspired by a rowing gesture for manual wheelchairs is shown. The innovative system of propulsion, named Handwheelchair.q, can be applied to wheelchairs employed in everyday life and to sports wheelchairs for speed races, such as [...] Read more.
In this paper, an innovative system of propulsion inspired by a rowing gesture for manual wheelchairs is shown. The innovative system of propulsion, named Handwheelchair.q, can be applied to wheelchairs employed in everyday life and to sports wheelchairs for speed races, such as Handbike and Wheelchair racing. The general features of the innovative system of propulsion and the functional designs of the different solutions are described in detail. In addition, the design of the mechanism for the transmission of motion, employed in a second prototype, Handwheelchair.q02, is presented and analysed. Finally, the dynamic model of the Handwheelchair.q has been developed in order to obtain important results for the executive design of Handwheelchair.q. Full article
(This article belongs to the Special Issue Advances of Italian Machine Design)
Figures

Figure 1

Open AccessArticle
A Comparative Study of Open-Source and Licensed CAD Software to Support Garment Development Learning
Received: 1 April 2019 / Revised: 24 April 2019 / Accepted: 26 April 2019 / Published: 1 May 2019
Viewed by 330 | PDF Full-text (1057 KB) | HTML Full-text | XML Full-text
Abstract
Most universities have included computer-aided design (CAD) pattern making systems education and training in their clothing technology courses in recent years, so as to respond to the actual needs of the fashion world for high-skilled fashion designers and clothing engineers. With the rapid [...] Read more.
Most universities have included computer-aided design (CAD) pattern making systems education and training in their clothing technology courses in recent years, so as to respond to the actual needs of the fashion world for high-skilled fashion designers and clothing engineers. With the rapid rise in the use of open source software (OSS) in all types of applications, it is important to know if the existing OSS CAD software for garment prototyping development can successfully support the learning process. The present study compares two commercial licensed CAD systems for pattern design (Polypattern and Create) to an open source software, Seamly2D, and to Wild Ginger’s Caveo V6 programme, which runs within an OSS. In total, two licensed and two OSS systems have been evaluated in their weights in accomplishing the garment development of ten different pattern designs. The results obtained for the evaluation of a set of OS and licensed CAD systems are presented and critically discussed. Full article
(This article belongs to the Special Issue Advances in CAD/CAM/CAE Technologies)
Figures

Figure 1

Open AccessArticle
Design for Disassembly (DfD) and Augmented Reality (AR): Case Study Applied to a Gearbox
Received: 6 March 2019 / Revised: 11 April 2019 / Accepted: 12 April 2019 / Published: 1 May 2019
Viewed by 291 | PDF Full-text (10349 KB) | HTML Full-text | XML Full-text
Abstract
Today’s market drives companies to change, adapt, and compete. Many consumers are increasingly looking at price, without sacrificing quality. In order to be attractive to the customer, companies must be able to offer the required quality at the lowest possible price. The life [...] Read more.
Today’s market drives companies to change, adapt, and compete. Many consumers are increasingly looking at price, without sacrificing quality. In order to be attractive to the customer, companies must be able to offer the required quality at the lowest possible price. The life cycle of many products has been shortened compared to the past because now technologies are evolving faster. For these reasons, it is important that companies reevaluate all the operations that are carried out within them, to optimize them and eventually adopt new technologies if they offer interesting opportunities. In this discussion, we first study the design for disassembly, a technique that can bring several advantages during the life cycle of a component, offering the possibility of reducing time and cost of disassembling a product, and better reuse of the different materials of which it is composed. Subsequently, augmented reality is discussed, and how this technology is exploited in the world, especially in the industrial sector. During the work, we discuss a case study, with the gearbox being the object of analysis. This allows us to apply the theoretical concepts illustrated in a concrete way, allowing for a better understanding of the topics. Full article
Figures

Figure 1

Open AccessArticle
Spectrum of Elementary Cellular Automata and Closed Chains of Contours
Received: 5 February 2019 / Revised: 22 April 2019 / Accepted: 25 April 2019 / Published: 30 April 2019
Viewed by 243 | PDF Full-text (269 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, we study the properties of some elementary automata. We have obtained the characteristics of these cellular automata. The concept of the spectrum for a more general class than the class of elementary automata is introduced. We introduce and study discrete [...] Read more.
In this paper, we study the properties of some elementary automata. We have obtained the characteristics of these cellular automata. The concept of the spectrum for a more general class than the class of elementary automata is introduced. We introduce and study discrete dynamical systems which represents the transport of mass on closed chains of contours. Particles on contours move in accordance with given rules. These dynamical systems can be interpreted as cellular automata. Contributions towards this study are as follows. The characteristics of some elementary cellular automata have been obtained. A theorem about the velocity of particles’ movement on the closed chain has been proved. It has been proved that, for any ε > 0 , there exists a chain with flow density ρ < ε such that the average flow particle velocity is less than the velocity of free movement. An interpretation of this system as a transport model is given. The spectrum of a binary closed chain with some conflict resolution rule is studied. Full article
Figures

Graphical abstract

Open AccessArticle
Development of a Delamination Fatigue Testing Machine for Composite Materials
Received: 11 March 2019 / Revised: 7 April 2019 / Accepted: 18 April 2019 / Published: 21 April 2019
Viewed by 357 | PDF Full-text (2747 KB) | HTML Full-text | XML Full-text
Abstract
Experimental studies on fatigue behavior are usually conducted on servo-hydraulic testing machines that are expensive and have high maintenance costs. In this work, a much simpler testing machine was developed, intended mainly for delamination fatigue tests on composite materials. After a literature review [...] Read more.
Experimental studies on fatigue behavior are usually conducted on servo-hydraulic testing machines that are expensive and have high maintenance costs. In this work, a much simpler testing machine was developed, intended mainly for delamination fatigue tests on composite materials. After a literature review on the methods and parameters of such tests, the machine was designed, and its parts manufactured and assembled into a fully operational testing machine. Additionally, the electrical components and the control and data acquisition software were also developed and implemented. Finally, several mode II delamination fatigue tests were conducted using the end-notched flexure test. The results were consistent with the well-known Paris law, which for composite materials relates the crack propagation rate to the strain-energy release rate range. Therefore, the developed machine seems to be an excellent alternative to the highly costly testing machines. Full article
Figures

Figure 1

Open AccessArticle
Adaptive Robust Vehicle Motion Control for Future Over-Actuated Vehicles
Received: 27 February 2019 / Revised: 14 April 2019 / Accepted: 17 April 2019 / Published: 19 April 2019
Viewed by 302 | PDF Full-text (2710 KB) | HTML Full-text | XML Full-text
Abstract
Many challenges still need to be overcome in the context of autonomous vehicles. These vehicles would be over-actuated and are expected to perform coupled maneuvers. In this paper, we first discuss the development of a global coupled vehicle model, and then we outline [...] Read more.
Many challenges still need to be overcome in the context of autonomous vehicles. These vehicles would be over-actuated and are expected to perform coupled maneuvers. In this paper, we first discuss the development of a global coupled vehicle model, and then we outline the control strategy that we believe should be applied in the context of over-actuated vehicles. A gain-scheduled H controller and an optimization-based Control Allocation algorithms are proposed. High-fidelity co-simulation results show the efficiency of the proposed control logic and the new possibilities that could offer. We expect that both car manufacturers and equipment suppliers would join forces to develop and standardize the proposed control architecture for future passenger cars. Full article
Figures

Graphical abstract

Open AccessArticle
Deep Learning-Based Landmark Detection for Mobile Robot Outdoor Localization
Received: 28 February 2019 / Revised: 13 April 2019 / Accepted: 16 April 2019 / Published: 18 April 2019
Viewed by 386 | PDF Full-text (3752 KB) | HTML Full-text | XML Full-text
Abstract
Outdoor mobile robot applications generally implement Global Positioning Systems (GPS) for localization tasks. However, GPS accuracy in outdoor localization has less accuracy in different environmental conditions. This paper presents two outdoor localization methods based on deep learning and landmark detection. The first localization [...] Read more.
Outdoor mobile robot applications generally implement Global Positioning Systems (GPS) for localization tasks. However, GPS accuracy in outdoor localization has less accuracy in different environmental conditions. This paper presents two outdoor localization methods based on deep learning and landmark detection. The first localization method is based on the Faster Regional-Convolutional Neural Network (Faster R-CNN) landmark detection in the captured image. Then, a feedforward neural network (FFNN) is trained to determine robot location coordinates and compass orientation from detected landmarks. The second localization employs a single convolutional neural network (CNN) to determine location and compass orientation from the whole image. The dataset consists of images, geolocation data and labeled bounding boxes to train and test two proposed localization methods. Results are illustrated with absolute errors from the comparisons between localization results and reference geolocation data in the dataset. The experimental results pointed both presented localization methods to be promising alternatives to GPS for outdoor localization. Full article
Figures

Figure 1

Open AccessArticle
Neural Network-Based Learning from Demonstration of an Autonomous Ground Robot
Received: 27 January 2019 / Revised: 10 April 2019 / Accepted: 10 April 2019 / Published: 15 April 2019
Viewed by 321 | PDF Full-text (522 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents and experimentally validates a concept of end-to-end imitation learning for autonomous systems by using a composite architecture of convolutional neural network (ConvNet) and Long Short Term Memory (LSTM) neural network. In particular, a spatio-temporal deep neural network is developed, which [...] Read more.
This paper presents and experimentally validates a concept of end-to-end imitation learning for autonomous systems by using a composite architecture of convolutional neural network (ConvNet) and Long Short Term Memory (LSTM) neural network. In particular, a spatio-temporal deep neural network is developed, which learns to imitate the policy used by a human supervisor to drive a car-like robot in a maze environment. The spatial and temporal components of the imitation model are learned by using deep convolutional network and recurrent neural network architectures, respectively. The imitation model learns the policy of a human supervisor as a function of laser light detection and ranging (LIDAR) data, which is then used in real time to drive a robot in an autonomous fashion in a laboratory setting. The performance of the proposed model for imitation learning is compared with that of several other state-of-the-art methods, reported in the machine learning literature, for spatial and temporal modeling. The learned policy is implemented on a robot using a Nvidia Jetson TX2 board which, in turn, is validated on test tracks. The proposed spatio-temporal model outperforms several other off-the-shelf machine learning techniques to learn the policy. Full article
Figures

Figure 1

Open AccessArticle
Tie-System Calibration for the Experimental Setup of Large Deployable Reflectors
Received: 11 March 2019 / Revised: 5 April 2019 / Accepted: 10 April 2019 / Published: 15 April 2019
Viewed by 295 | PDF Full-text (1150 KB) | HTML Full-text | XML Full-text
Abstract
The trade-off between the design phase and the experimental setup is crucial in satisfying the accuracy requirements of large deployable reflectors. Manufacturing errors and tolerances change the root mean square (RMS) of the reflecting surface and require careful calibration of the tie-rod system [...] Read more.
The trade-off between the design phase and the experimental setup is crucial in satisfying the accuracy requirements of large deployable reflectors. Manufacturing errors and tolerances change the root mean square (RMS) of the reflecting surface and require careful calibration of the tie-rod system to be able to fit into the initial design specifications. To give a possible solution to this problem, two calibration methods—for rigid and flexible ring truss supports, respectively—are described in this study. Starting from the acquired experimental data on the net nodal co-ordinates, the initial problem of satisfying the static equilibrium with the measured configuration is described. Then, two constrained optimization problems (for rigid or flexible ring truss supports) are defined to meet the desired RMS accuracy of the reflecting surface by modifying the tie lengths. Finally, a case study to demonstrate the validity of the proposed methods is presented. Full article
Figures

Figure 1

Open AccessArticle
Tailor-Made Hand Exoskeletons at the University of Florence: From Kinematics to Mechatronic Design
Received: 13 March 2019 / Revised: 31 March 2019 / Accepted: 2 April 2019 / Published: 3 April 2019
Viewed by 353 | PDF Full-text (3300 KB) | HTML Full-text | XML Full-text
Abstract
Recently, robotics has increasingly become a companion for the human being and assisting physically impaired people with robotic devices is showing encouraging signs regarding the application of this largely investigated technology to the clinical field. As of today, however, exoskeleton design can still [...] Read more.
Recently, robotics has increasingly become a companion for the human being and assisting physically impaired people with robotic devices is showing encouraging signs regarding the application of this largely investigated technology to the clinical field. As of today, however, exoskeleton design can still be considered a hurdle task and, even in modern robotics, aiding those patients who have lost or injured their limbs is surely one of the most challenging goal. In this framework, the research activity carried out by the Department of Industrial Engineering of the University of Florence concentrated on the development of portable, wearable and highly customizable hand exoskeletons to aid patients suffering from hand disabilities, and on the definition of patient-centered design strategies to tailor-made devices specifically developed on the different users’ needs. Three hand exoskeletons versions will be presented in this paper proving the major taken steps in mechanical designing and controlling a compact and lightweight solution. The performance of the resulting systems has been tested in a real-use scenario. The obtained results have been satisfying, indicating that the derived solutions may constitute a valid alternative to existing hand exoskeletons so far studied in the rehabilitation and assistance fields. Full article
(This article belongs to the Special Issue Advances of Italian Machine Design)
Figures

Figure 1

Open AccessReview
Interoperability in Smart Manufacturing: Research Challenges
Received: 11 February 2019 / Revised: 5 March 2019 / Accepted: 15 March 2019 / Published: 2 April 2019
Viewed by 537 | PDF Full-text (2310 KB) | HTML Full-text | XML Full-text
Abstract
Recent advances in manufacturing technology, such as cyber–physical systems, industrial Internet, AI (Artificial Intelligence), and machine learning have driven the evolution of manufacturing architectures into integrated networks of automation devices, services, and enterprises. One of the resulting challenges of this evolution is the [...] Read more.
Recent advances in manufacturing technology, such as cyber–physical systems, industrial Internet, AI (Artificial Intelligence), and machine learning have driven the evolution of manufacturing architectures into integrated networks of automation devices, services, and enterprises. One of the resulting challenges of this evolution is the increased need for interoperability at different levels of the manufacturing ecosystem. The scope ranges from shop–floor software, devices, and control systems to Internet-based cloud-platforms, providing various services on-demand. Successful implementation of interoperability in smart manufacturing would, thus, result in effective communication and error-prone data-exchange between machines, sensors, actuators, users, systems, and platforms. A significant challenge to this is the architecture and the platforms that are used by machines and software packages. A better understanding of the subject can be achieved by studying industry-specific communication protocols and their respective logical semantics. A review of research conducted in this area is provided in this article to gain perspective on the various dimensions and types of interoperability. This article provides a multi-faceted approach to the research area of interoperability by reviewing key concepts and existing research efforts in the domain, as well as by discussing challenges and solutions. Full article
(This article belongs to the Special Issue Smart Manufacturing, Digital Supply Chains and Industry 4.0)
Figures

Figure 1

Machines EISSN 2075-1702 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top