Virtual prototyping and digital twin

This paper presents a new concept of a desktop tangible shape display for virtual surface rendering. The proposed system is able to represent in the real environment the shape of a digital model of a product, which can be explored naturally through a free-hand interaction. Aim of the shape display is to allow product designers to explore the rendered surface through a continuous touch of curves lying on the product shape. Ideally, the designer selects curves, which can be considered as style features of the shape, on the shape surface, and evaluates the aesthetic quality of these curves by manual exploration. In order to physically represent these selected curves, a flexible surface is modelled by means of servo-actuated modules controlling a physical deforming strip. The behaviour of the strip is controlled by acting on the position and rotations of a discrete number of control sectors. Each control sector is controlled by a module, which is based on an absolute positioning approach and equipped with five degrees of freedom. The developed system is able to manage the elastic behaviour of the strip in terms of bending, twisting and local tangency. The tangency control allows us to manage the local tangency of the strip to the rendered trajectory, thus increasing the accuracy of the representation. Moreover, a preliminary second version of the module is presented, which has been designed so as to allow the control sectors to slide on the strip. Thanks to this feature, it will be possible to place the control sector in a given point of the trajectory, such as point of maximum, point of minimum or inflection points. The device is designed to be portable, low cost, modular and high performing in terms of types of shapes that can be represented. A prototype equipped with three modules has been developed in order to evaluate the usability and the performances of the display.

The study of experience in the interaction with goods, both physical and virtual, is consistently affected by the role of the context in which this interaction occurs. The paper analyses the global problem starting from three independent variables: product, people and context, and focuses on the analysis of single couples of independent variables: goods-person, goodscontext and person-context. From this analysis it is derived a general framework oriented to the experimenting and validation of the use of Virtual Prototyping to optimize the perceived value of products To-Be.

The sense of smell has a great importance in our daily life. In recent years, smells have been used for marketing purposes with the aim of improving the person's mood and of communicating information about products as household cleaners and food. However, the scent design discipline can be also applied to any kind of products to communicate their features to customers. In the area of Virtual Reality several researches have focused on integrating smells in virtual environments. The research questions addressed in this work concern whether Virtual Prototypes, including the sense of smell, can be used for evaluating products as effectively as studies performed in real environments, and also whether smells can contribute to increase the users' sense of presence in the virtual environment. For this purpose, a Virtual Reality experimental framework including a prototype of a wearable olfactory display has been set up, and experimental tests have been performed.

Emotional expression is an important human behaviour, which enriches communication. Sensory organs play crucial role in emotional perception. Today communication is mostly done via digital mediators, which dominantly address to vision excluding the other senses; therefore, communication becomes less affective. Wearable technology can appeal to sensory organs from very close distance due to its intimate interaction with human body. Hence, this technology can be used in order to make distant communication more affective by enabling multisensory interaction. This paper represents a user-centred design practice on wearable products that simulate sensorial feedbacks (tactile, visual and auditory) to express basic emotions. Three prototypes that transmit emotional messages were designed, built and tested to observe user behaviour. This paper discusses how user experience obtained through the user test can be taken further to design new communication products.

Keywords: Design practice , Emotion , Sensory perception , Wearable technology

This paper deals with the design and implementation of a double wishbone front suspension for a vineyard-orchard tractor, developed in conjunction with a major tractor brand. To date, independent front suspensions are only found on commercial tractors over 150 kW. A front suspended axle is recognized as a popular option in improving tractor ride performance on larger vehicles. Despite their narrow track, vineyard-orchard tractors are required to have good lateral stability and stability on slopes (i.e. at least 28° rollover angle) and an extremely tight turning diameter for a 4WD vehicle (less than 7 m). The discussion is concered with retrofitting an existing vehicle with a double wishbone front suspension. This paper focuses on the layout and kinematic analysis phases of the design process. These were conducted in collaboration with the vehicle manufacturer to demonstrate suspension feasibility in terms of available space and correct kinematic layout. The final kinematic turning diameter obtained is about 6.4 m, with a ±65 mm suspension travel available. The roll centre height value is not very sensitive to steering (about -95 mm excursion in the Z axis from no-steer position to full steer).

Keywords: Double wishbone suspension , Front axle independent suspension , Narrow-track tractor , Suspension design

The present work describes the interactive prototype and the preliminary evaluation results of a tool dedicated to the light General Aviation pilot's community. The tool's interface has been developed through an Android tablet application and aims at supporting the pilots in the task of staying “well-clear” from the surrounding traffic by presenting them the long-term prediction of the flights. The initial results and the approach of a heuristic evaluation conducted with five experts coming from the fields of user-experience, aviation and automotive are discussed along with the improvements in the design of the user-interface focusing on the trajectory depictions.

Keywords: Heuristic evaluation , Light general aviation , Trajectory prediction visualization , User-interface design

All future power developments should consider as primary tasks the achievement of the required emission levels and CO2-values, while still providing optimum torque-to-rpm curves, the lowest SFC (Specific Fuel Consumption) over the widest range possible, good power-to-weight and affordable costs. One method to achieve these objectives is the downsizing. To achieve the levels of engine performance that are required, a significant increase in the rated speed and in the boost pressure is mandatory. In this case, the result is an increase in the flow rate through the intake and exhaust ports and valves. Considering the impact of these changes, the port layout of the system is reanalyzed. Another physical limit to the maximum speed depends on the CR (Common Rail) injector dynamic performances. These performances decrease with size for inertia problems and they depend on the amount of effort involved in their development. Automotive engines in the range of 10 to 100 HP per cylinder are the most common. For this reason, these injectors are the most advanced and costeffective. Furthermore, their small size and inertia is favorable to the best dynamic performance. The larger number of nozzles improves combustion performance. In fact the better surface to volume ratio or the spray improves heat transfer. For this reason, multiple injection systems can be used in the modern HSDI (High Speed Direct Injection) CR large diesels. This solution was commonplace before WWII, but has been progressively abandoned with the introduction of mechanical high-pressure injection systems and the bowl combustion chamber. In this paper, a dual combustion chamber per cylinder engine is considered. The primary purpose of this study is to examine the best port layout on a modern diesel combustion system and to introduce a new promising concept. The study included flow measurements of intake flow and CFD simulations of the flow field during intake. This design enables the formation of two homogenous swirls centered onto the injectors, with excellent flow coefficient. The design also allows an increase in volumetric efficiency combined with a reduction in flow losses.

Keywords: Diesel engines , Multiple injections , Multiple swirls

A method to perform the preliminary design of an impeller for an extremely high pressure ratio centrifugal compressor is introduced in this paper. The equations used are fully detailed and a design procedure is introduced. This design procedure required a GA (Genetic Algorithm) optimization to obtain an acceptable optimum result. It is demonstrated that a 8:1 compressor can be designed for a mass flow of 500 kg/h. This GA optimized initial design should be then be validated through CFD (Computational Fluid Dynamics) simulation and then tested on a test bench. However, the initial design phase is critical, since a CAD model of the impeller is needed to start the simulation process. In our case this initial phase couldn't be inspired by existing design, since none were found. Aircraft and Helicopter engines do not have the problem of turbo lag, since fan/propeller inertia eliminates this problem. On the contrary these engines necessitate of performance at altitudes (flight levels) much higher than automotive applications. Small turbochargers with high compressor ratio are not available on the market, so a special design is needed.

Human Robot Collaboration (HRC) have proved to be effective if compared to traditional hybrid automation in assembly tasks, especially when human-like sensitivity and high quality are required. However, a rigorous engineering design is mandatory in order to successfully apply HRC to Industry. Academy and Industry are asked to jointly work for exploiting the technical opportunities given by robots and humans. Scientific literature often describes the application of HRC in manufacturing but rarely presents systematic engineering design approaches. The present paper investigates and describes the systematic design of a HRC workcell for assembling bio-medical products. Moreover, productivity and profitability of the developed solution are evaluated and discussed.

Keywords: Assembly , Biomedical products , Human-Robot Collaboration

Accessibility to graphical user interfaces by visually impaired persons is generally enabled through systems, which reproduce the lexical structure of the user interface to a nonvisual form, mainly employing 3D audio output techniques. Two main critical issues have been identified: (i) most interfaces address the needs and abilities of sighted users and consequently the reproduction is only a translation from one language to another; (ii) blind users are generally not involved in the development stage due to the cost of prototyping. The present work proposes an interactive user interface to control a multi-sensory shower accessible by both sighted and blind users and able to adapt its control knob to reproduce Braille texts. Such function is realized by the integration of an electrotactile feedback device and adopts soft touch finishing to better stimulate touch sensations. Haptic technologies have been exploited to create a virtual high-fidelity prototype to assess individual end-users' response during the user interface design process. The paper illustrates the designed interface to assist blind users in home environments and the adopted virtual prototyping technique to address the above-mentioned issues.

The paper deals with the design issues concerning the remote maintenance of divertors in fusion advanced studies torus (FAST), a satellite tokamak acting as a test bed for the study and the develop of innovative technologies oriented to ITER and DEMO programs, pilot examples of the feasibility of energy production from nuclear fusion on the Earth. FAST remote handling (RH) solutions are provided according to an "interactive design review" philosophy based on virtual prototyping techniques. Assuming an ITER configuration as start point, it foresees an iterative process of design review, carried out in virtual reality (VR) environment and oriented to obtain a sort of best solution from the RH point of view. Any iteration includes the analysis of the current solution and the proposal of new and alternative ones, based on the requirements fulfillment and the improvement of critical points highlighted. In such a way, and this is the main novelty introduced by the paper, the interactive design review in a VR collaborative environment becomes the tool able to put in cooperation and in positive competition various and different competences, required by a multidisciplinary problem as the realization of nuclear fusion machine, in order to reach a shared solution. A first preliminary FAST RH solution is hereinafter presented, accompanied by the design of a compatible support system, due to the strict relationship between the divertor maintenance and the support configuration. The work was carried out via the collaboration of the "Divertor Test Platform 2" (DTP2) team, in charge of ITER divertor RH tests and located in VTT's Labs of Tampere (Finland), and the IDEAinVR team of CREATE Consortium, with competence in interactive design and VR simulations and located in the Virtual Reality Lab of University of Naples Federico II (Italy). © 2013 Springer-Verlag France.

Keywords: Fusion engineering , Interactive design , Remote handling , Tokamak design , Virtual prototyping

The object of this paper is the development of a decision support system involved in the bidding for invitations to tender in the railway field. The proposed methodology is based on the characterization of the whole train and its components, through several attributes according to a digital pattern approach. In particular some key components were chosen such as the traction motor, the bogie and the auxiliary equipment converter. The system measures the extent to which the products offered by the company fit the one required by the customer, comparing the homologous attributes. Such analysis is called 'adopt/adapt/innovate' (AAI). In this way it is possible to identify products already designed that fully or partly fit what required, obtaining huge benefits in terms of effectiveness and efficiency.

Keywords: Bid , Decision support system , Digital pattern , Digital portfolio , Virtual prototyping

In this work the mechanical behaviour of a core reinforced composite sandwich structure is studied. The sandwich employs a Glass Reinforced Polymer (GRP) orthotropic material for both the two external skins and the inner core web. In particular, the core is designed in order to cooperate with the GRP skins in membrane and flexural properties by means of the addition of a corrugated laminate into the foam core. An analytical model has been developed to replace a unit cell of this structure with an orthotropic equivalent thick plate that reproduces the in plane and out of plane behaviour of the original geometry. Different validation procedures have been implemented to verify the quality of the proposed method. At first a comparison has been performed between the analytical model and the original unit cell modelled with a Finite Element mesh. Elementary loading conditions are reproduced and results are compared. Once the reliability of the analytical model was assessed, this homogenised model was implemented within the formulation of a shell finite element. The goal of this step is to simplify the FE analysis of complex structures made of corrugated core sandwiches; in fact, by using the homogenised element, the global response of a real structure can be investigated only with the discretization of its mid-surface. Advantages are mainly in terms of time to solution saving and CAD modelling simplification. Last step is then the comparison between this FE model and experiments made on sandwich beams and panels whose skins and corrugated cores are made of orthotropic cross-ply GRP laminates. Good agreement between experimental and numerical results confirms the validity of the proposed model.

Keywords: Corrugated Core , Finite Element , Homogenisation , Sandwich Structures

Total reverse shoulder arthroplasty is becoming more and more the standard therapeutic practice for glenohumeral arthropathy with massive lesions of the rotator cuff. The biomechanical principle of this prosthesis is represented by the reversion of the normal anatomy of the shoulder joint. This non-anatomical prosthesis leads to a medialization of the rotation centre of the glenohumeral joint and also to a distalization of the humeral head. All that causes a deltoid tension increasing so allowing a larger abduction of the arm. Main complications of the reverse shoulder prosthesis are due to the joint instability, the scapular notching and the wear of the polyethylene insert. Purpose: The main goal of the present work is to study the effect of the positioning of the humeral component on the intrinsic stability of the reverse shoulder prosthesis. In particular, through finite element method simulations, the variation of the stability ratio of the shoulder joint has been calculated for both vertical and horizontal dislocating loads depending on the humeral stem version angle. Moreover, in order to estimate the wear of the polyethylene cup, some analyses have been developed to calculate the pressures on the polyethylene insert. Results: The obtained results demonstrate the dislocation of a shoulder prosthesis and the wear of the polyethylene insert can be prevented or limited by conveniently varying the version angle of the humeral component. © 2013 Istituto Ortopedico Rizzoli.

Keywords: FEM analyses , Intrinsic stability , Polyethylene wear , Stability ratio , Total reverse shoulder arthroplasty

A novel design for a dielectric elastomer (DE) actuator is presented. The actuator is obtained by coupling a cylindrical DE film with a series of slender beams axially loaded beyond their buckling limit. Similar to previous published solutions, where different actuator geometries were coupled with compliant mechanisms of various topologies, the elastic beams are designed so as to provide a suitable compensating force that allows obtaining a quasi-constant available thrust along the entire actuator stroke. Whilst the elastic beam are sized on the basis of an analytical procedure, the overall system performance is evaluated by means of multiphysics finite element (FE) analysis, accounting for the large deflection of the buckled-beam springs (BBSs) and for the DE material hyperelasticity. Numerical and experimental results are finally provided, which demonstrate the prediction capabilities of the proposed modeling method and confirm that well-behaved cylindrical actuators can be conceived and produced.

In the field of pharmaceutical processing, last generation automatic machines autonomously modify their behavior in order to achieve the best manufacturing quality and productivity despite ever changing process requirements. Mechatronics, as a synergistic integration of electro-mechanical equipment and software control logics, enables such adaptive self-optimizing behaviors. Unfortunately, due to the complex interactions between the different technologies, the final performance of these systems can be effectively validated and optimized only on a physical prototype, with limited possibilities to introduce possible design changes. Therefore, in order to enable validation/optimization of high performance machinery during engineering design stage, a mechatronic Virtual Prototyping (VP) technology is strongly needed. Within this context, the present work discusses a mechatronic VP method based on a Hardware-in-the-Loop, hybrid-process simulation approach, where interactive real-time simulations can effectively assess the real final performance under changing process scenarios. In particular, a case study concerning a high-speed automatic machines for pharmaceutical capsules filling is thoroughly discussed.

Keywords: Hardware-in-the-Loop , Intelligent Manufacturing , Mechatronic Design , Virtual Prototyping

Simulation-Based-Training (SBT) allows to train the operators of complex machinery within a safe virtual environment by means of effective lifelike learning experiences. SBT has been efficiently used in medical, aerospace and military fields and it may provide a competitive advantage also for the training of operators in mechatronic plants. In fact, at the current state of the art, human-machine interaction still heavily impacts on the final performances of automated plants. Since the fast-evolving process dynamics of the machinery is controlled and supervised by complex software logics, the main challenge for effective and valid SBT concerns the development of a real-time simulation, where the control system responsiveness is fully reproduced. This paper deals with a novel SBT workbench used for steel plants operator training, discussing the real-time simulation architecture developed for the purpose. Following a hybrid process simulation approach, real-time control Hardware-In-the-Loop technology assures seamless and accurate reproduction of the real plant, also achieving the desired Man-in-the-Loop practice for the operator interaction. A conceptual architecture for a virtual interactive prototype is proposed, including controllers and interfaces for trainer and trainees. A case study on an electric arc furnace is implemented within a Virtual Commissioning tool, analyzing its capabilities and limitations.

Multipurpose and programmable servo-actuated mechanisms may be envisaged as the key technology for increasing flexibility and re-configurability of modern automated machinery. Unfortunately, based on the current state-of-the-art, these mechatronic devices are extremely flexible but generally energy intensive, thus compromising the overall system sustainability. Nonetheless, the system power consumption can be partially reduced if energy optimality is introduced as a design goal along with the global productivity. Naturally, as a first step towards the practical implementation of any energy-optimality criterion, the end user should be capable of predicting the system power flow, including the major sources of energy loss. In this context, this paper firstly presents a reliable model of a servo-actuated mechanism accounting for linkage, electric motor and power converter behavior. Then, a novel identification method is discussed, which allows the separate determination of the models parameters by means of non-invasive experimental measures. The method is finally validated by comparing predicted and actual power flows in a simple mechatronic system, which is composed of a slider-crank mechanism directly coupled with a position-controlled permanent magnet synchronous motor.

Dielectric Elastomers (DEs) are deformable dielectrics, which are currently used as active materials in mechatronic transducers, such as actuators, sensors and generators. Nonetheless, at the present state of the art, the industrial exploitation of DE-based devices is still hampered by the irregular electro-mechanical behavior of the employed materials, also due to the unpredictable effects of environmental changes in real world applications. In many cases, DE transducers are still developed via trial-and-error procedures rather than through a well-structured design practice, one reason being the lack of experimental data along with reliable constitutive parameters of many potential DE materials. Therefore, in order to provide the practicing engineer with some essential information, an open-access database for DE materials has been recently created and presented in [1]. Following the same direction, this paper addresses the temperature effect on the visco-hyperelastic behavior of two DE candidates, namely a natural rubber (ZRUNEK A1040) and a well-known acrylic elastomer (3M VHB 4905). Measurements are performed on pure shear specimens placed in a climactic chamber. Experimental stress-strain curves are then provided, which makes it possible to predict hyperelasticity, plasticity, viscosity, and Mullins effect as function of the environmental temperature. Properties of these commercial elastomeric membranes are finally entered in the database and made available to the research community.

This paper quantitatively reports about potential energy savings on robotic assembly lines for the automotive industry. At first, a detailed system model is described, which improves previously published results by explicitly considering both manipulator and electrical drive dynamics. The model closely captures experimental data in terms of actuation torques and servodrive voltages, which are directly used to derive the plant input power. Two practical methods are then evaluated for reducing the overall energy consumption. The methods rely on: 1) implementation of energy-optimal trajectories obtained by means of time scaling, concerning the robots' motion from the last process point to the home positions and 2) reduction of energy consumption by releasing the actuator brakes earlier when the robots are kept stationary. Simulation results, based on the production timing characteristics measured at a real plant, clearly shows that the system energy consumption can be effectively reduced without negative effects on the production rate. © 2004-2012 IEEE.

Keywords: Energy efficient robotics , robotic manufacturing , trajectory planning , virtual prototyping