Virtual prototyping and digital twin

The haptic feedback perceived during the interaction with consumer products is an important aspect since it concurs in creating, together with the aesthetic features and sonic feedback, the emotional response during the first contacts with a product. And this may be decisive for the user's decision of purchasing a product instead of another one. So the design of the haptic behavior of interaction elements of products can be both a successful strategy for capturing consumers' attention but even a need for avoiding problems during the use. The paper describes the process of virtualization of the interaction with an industrial consumer product by means of haptic, sound and visualization technologies in order to obtain a prototype (interactive Virtual Prototypes) useful to design and test the haptic feedback of interaction elements directly with end users. Copyright © 2011 by ASME.

This paper describes the servo actuated transmission system required to drive a desktop haptic strip interface. The haptic strip is a mechatronic device which is used for exploration of virtual surfaces with aesthetic value. The simulation of tasks, such as the exploration of aesthetic real surfaces made by industrial designers in order to check the quality of prototypes, require full hand contact with the shape on a one-to-one scaled representation of the object. Our mechatronic device allows a continuous, free hand contact on a developable real plastic tape actuated by a servo-controlled mechanism in which is used the tessellation approach. In fact, the triangular mesh simplifies the conformation of the developable real surface as the virtual one. This paper discusses the design concept, novel kinematics and mechanics, improvements of the transmission system and control for the Desktop Strip. © 2011 by ASME.

The ability to capture customers' needs and the voice of customers, and to translate them into a set of product specifications that at best satisfy the target customers has increasingly become a key element of business strategy. The common practice consists in evaluating products at the end of the design process through physical prototypes with the participation of users and potential customers. The same practice can be implemented by using virtual replica of real products, reducing cost and time necessary to build some variants. The paper presents a methodology for the development of the virtual prototype of a piece of furniture, produced by a company that is interested in studying how customers perceive and evaluate some variants of the hinge mechanism. The virtual prototype has been implemented using a tool for virtual reality applications oriented to non-expert programmers. The modularity and flexibility of the approach used for implementing the virtual replica has allowed us to re-use the components, and to easily change the parameters, also during the test activities. © 2011 Springer-Verlag.

Keywords: Fast Prototyping , Virtual Products , Virtual Prototyping

Several haptic devices have been developed in recent years in order to reproduce the sensation of physical contact with virtual objects. Many of these devices are point-based, and some haptic interfaces behave like small surfaces that conform to a virtual shape. None of these allow a full-hand contact with the shape, and they are, in general, too small to render big surfaces. The simulation of tasks, such as the exploration of aesthetic surfaces made by industrial designers in order to check the quality of prototypes, require full-hand contact with the shape on a one-to-one scaled representation of the object. These explorations follow trajectories that can be approximated with planar or geodesic curves. In this paper, we describe the design and implementation of a linear haptic device that is able to render these trajectories. The device is part of a multimodal system including stereoscopic visualization that allows visual representation of the entire surface. Industrial designers use the system for checking the quality of shapes while exploiting their manual and visual skills. The system has been tested by industrial designers and the results are reported in this paper. © 2011 IEEE.

Keywords: curve rendering , Haptic strip , industrial design , mixed reality , multimodal interfaces , virtual prototyping

Virtual Prototyping (VP) aims at substituting physical prototypes currently used in the industrial design practice with their virtual replica. The ultimate goal of VP is reducing the cost and time necessary to implement and test different design solutions. The paper describes a pilot study that aims at understanding how interactive Virtual Prototypes (iVPs) of consumer products (where interaction is based on the combination of haptic, sound and 3D visualization technologies) would allow us to design the interaction parameters that concur in creating the first impression of the products that customers have when interacting with them. We have selected two commercially available products and, once created the corresponding virtual replica, we have first checked the fidelity of the iVPs by comparing them with the corresponding real products, when used to perform the same activities. Then, differently from the traditional use of Virtual Prototypes for product design evaluation, we have used them for haptic interaction design, i.e. as a means to define some design variables used for the specification of new products: variations are applied to iVP haptic parameters so as to test with final users their preferences concerning the haptic interaction with a simulated product. The iVP configuration that users liked most has then been used for the definition of the specifications for the design of the new product. © 2011 IEEE.

Keywords: I.3.6 [Computing Methodologies]: Methodology and TechniquesInteraction techniques , J.6 [Computer Applications]: COMPUTERAIDED ENGINEERINGComputer-aided design (CAD)

The paper describes the use of interactive Virtual Prototypes (iVP) for the specification of consumer products and for the evaluation of the perceived quality of the product already in its conceptual form. iVPs are based on multimodal interaction including force-feedback and sound in addition to 3D stereoscopic visualization. The fidelity of the prototypes has been evaluated in comparison with the corresponding real products, when used for performing the same tests. Differently from the traditional use of Virtual Prototypes, which aims at evaluating the product design, we have used iVPs for the interaction design of a new product, i.e. it has been used as a means to define the design parameters used for the specification of a new product. © 2011 IEEE.

Keywords: I.3.6 [Computing Methodologies]: Methodology and TechniquesInteraction techniques , J.6 [Computer Applications]: COMPUTERAIDED ENGINEERINGComputer-aided design (CAD)

Ballistic requirements in the design of military aerospace components are critical for the structural assessment. Although experimental tests remain fundamental, numerical analyses allow us to simulate such a very complex scenario. However, in order to improve the consistency of such simulations, several aspects have to be considered in detail. The material behavior is a key one: constitutive laws, able to describe the material behavior in terms of hardening, strain rate, damage criteria, temperature, etc⋯, is fundamental. Moreover a detailed validation of numerical results is needed. The analysis of ballistic data (such as the residual velocity and the direction of the bullet after the impact) is only one option, but reliable simulations of damage shape and size are the real target. Therefore the paper will focus on the comparison between the experimental damage and the simulated one using a 3D acquisition of the experimental impacted area. This approach allows us not only to evaluate the damage in the macroscale field but also in the near micro-scale: shape on the border of the damage. © 2011 Published by Elsevier Ltd.

Keywords: AL-6061-T6 shaft , Ballistic impact , NATO 7.62 mm , Numerical simulations , Reversal engineering

The valve return springs in the distribution chain of internal combustion engines constitute a fundamental component for the duration, efficiency and performance of the engine itself [1,2,3,4]. This is even more true for high-performance engines whose mechanical and thermal power leads to the premature deterioration of poorly designed components. The elevated forces in such engines necessitate, where the valve springs have not been substituted by alternative kinematic systems, progressive springs, i.e. springs with variable stiffness. Despite this fact, the literature does not contain any univocal methods for defining the geometry of this type of spring. In the present study, the question is approached on the basis of a numerical-iterative calculation, providing a general methodology which, starting from data regarding the functioning of the engine and the geometric volumes to be respected, leads to the definition of the optimal geometry of the helix, taking account of the trend of the stiffness, of the natural frequencies and of the loads over the entire operating range of the spring. Tests on springs calculated in this way were performed using multi-body software, in order to verify the correspondence between the initial design data and the real behaviour of the geometry generated. © 2011 SAE International.

The valve return springs in the distribution chain of internal combustion engines constitute a fundamental component for the duration, efficiency and performance of the engine itself [1,2,3,4]. This is even more true for high-performance engines whose mechanical and thermal power leads to the premature deterioration of poorly designed components. The elevated forces in such engines necessitate, where the valve springs have not been substituted by alternative kinematic systems, progressive springs, i.e. springs with variable stiffness. Despite this fact, the literature does not contain any univocal methods for defining the geometry of this type of spring. In the present study, the question is approached on the basis of a numerical-iterative calculation, providing a general methodology which, starting from data regarding the functioning of the engine and the geometric volumes to be respected, leads to the definition of the optimal geometry of the helix, taking account of the trend of the stiffness, of the natural frequencies and of the loads over the entire operating range of the spring. Tests on springs calculated in this way were performed using multi-body software, in order to verify the correspondence between the initial design data and the real behaviour of the geometry generated. Copyright © 2011 SAE International.

Engine efficiency and optimization are key aspects for automotive manufacturers. Lamborghini has particularly focus attention for reduction of time to market building up a synergic approach for new component's development using simulation, Know-how experiences, engine engineering expertise and experimental validation. In particular to reach the best results in the shortest time it is used, in the preliminary stage of development, a massive support of simulation analysis. In the Lamborghini approach analysis and simulation has become key aspects during concept and development of timing drives. This type of activity is used to support the development of better chain timing drives focusing on improving durability, lower friction, less noise and reduced cost in less time than conventional trial and processes. Even during the concept design phase it is useful to use a mathematical model to calculate dynamic forces and motions of a chain drive. These models are used to assess in detail the choice of drive layout, to check that component load limits are not exceeded and to make a first choice of the tensioner settings. Later, when the first prototype engines are available, measurements of timing drive sprocket motion, tensioner motion and tensioner force are typically taken. At this stage the model can be correlated to the measured data and then the correlated model can then be used to explore the potential for improvements to the timing drive during later phases of engine development. This paper describes the correlation of a mathematical model of a complex timing chain drive for a Lamborghini V12 gasoline engine to measurements made on a prototype engine. The depth of model required and the choice of stiffness and damping values needed to give excellent agreement between calculations and measured data are discussed. © 2011 SAE International.

The design of industrial plants requires managing many geometrical and non geometrical data to reach a satisfactory solution in terms of costs, performance and quality. An approach is presented to support designers in the elicitation and formalization phase of the required knowledge. Then an integral prototypal software application accomplishes layout configuration tasks through a customized graphic wizard. A routing algorithm is presented to automate calculation and modelling of piping and electrical cables respecting design constraints. Cogeneration plant powered by micro gas-turbines has been chosen as test case to evaluate the proposed design method and tool. © Springer-Verlag Berlin Heidelberg 2011.

Keywords: Cogeneration , Computer aided plant design , Knowledge based systems , Knowledge management , Routing

Several simple models, such as conicoid models, are usually adopted to describe the surfaces of the human crystalline lens; unfortunately they do not provide a continuous junction between the anterior and the posterior surface of the lens and then they cannot qualify for biomechanical simulation. Vice versa, more complex mathematical models give a continuous junction between the anterior and the posterior surface, but do not provide a geometrical or optical interpretation of the coefficients of the model. In this work we propose a continuous curvature lens model in which the coefficients are derived by geometrical constraints. In this way, both the continuity in the junction zone and a geometrical-physical interpretation of the coefficient involved in the model are obtained. Shape, volume and curvature of the proposed model were compared with four models presented in the literature: two independent conic equations, two interdependent figuring conicoid equations, conic patches model and modulated hyperbolic cosine. © 2011 Copyright Taylor and Francis Group, LLC.

Keywords: curvature , geometrical constraint , human crystalline lens , shape , volume

The structure of Cubesat that will be presented in the following paper was realized within the activities of Space Robotics Laboratory (SRL) and the V-Lab of the II Faculty of Engineering of Bologna University in collaboration with the Space System group of University of Rome "LA SAPIENZA". The work team that is persecuting the project proposed is composed by PHD, master and bachelor students. Several projects aimed at hands-on education are developed by the SRL including: an observatory for observation and monitoring of space debris and the creation of payloads for sounding rockets and stratospheric balloons, that are part of the ESA education program; together with the realization of the Cubesat depicted in the paper. Cubesat is a cube-shaped nano-satellite with the side of 100 mm. Despite its small size, it has a system for attitude control, a telecommunication system, a camera and a power system. Considering the size and requirements of the various systems, the organization of interior spaces was one of the major issues in the design of the structure for which it was necessary to identify innovative solutions. The Cubesat structure was realized by polymer (ABS - Acrylonitrile - Butadiene - Styrene) with the technique of "rapid prototyping" thanks to equipment provided by the V-Lab of the II Faculty of Engineering of University of Bologna. The Rapid Prototyping technique has several advantages including the quick implementation and low cost. Moreover, for the construction of a small satellite it is very useful the ability to succeed in details, sometimes difficult to achieve with the use of tools machine except with a significant increase in costs. Another important advantage is the ability to use a material with a lower density than the commonly used aluminum alloy. The structure must be able to resist at the stresses due to the launch vibrational and static loads. For this several simulations using a FEM code have been performed during the design phase, moreover a Test-Pod system in aluminum alloy was built and used to perform vibration tests for the qualification to launch with Indian PLSV launcher of the Cubesat prototype. The paper shows the detailed design of the Cubesat with the analysis of solutions to the critical points, the results of numerical simulations and the results of vibration tests carried out for the launch qualify on the Cubesat prototype. Copyright ©2010 by the International Astronautical Federation. All rights reserved.

Nowadays, Virtual Prototyping (VP) methods are widely used for product design and development purposes. In particular, VP methods are now used also for the orthopedic products development process, to better understand the functional performance of prostheses or implants within the musculoskeletal system. In fact, developing validated virtual models of joints or of other anatomical structures may reduce design and prototyping costs and compress development cycles. The purpose of this paper is to point out first the state of art of both the VP technologies and the kinds of virtual models used in the medical field, with particular attention to those used for the design and development of orthopedic products. Then, it focuses on a qualitative analysis of some biomechanical simulation software packages (LifeMOD, AnyBody, and OpenSim) as tools for the improvement of the product design and development processes. Copyright © 2011 by ASME.

Keywords: Biomechanical simulation , Orthopedic devices , Product design and development cycle , Virtual prototyping

Materials simulation in virtual prototyping is one of the most challenging issues as not completely fulfilled by current devices. It allows Virtual Reality-based interfaces to provide multisensory interaction and to enhance product experience by mainly stimulating user emotional response. In this context the paper presents a new tactile simulation approach based on material surface properties elaboration and processing to stimulate roughness and texture coarseness perception. The developed approach leads to the development of a tactile display and a software tool to manage the configuration of selective stimulating signals. The main problem the research aims at overcoming, regards with the nature of signals adopted by most electrotactile displays and the way to stimulate skin mechanoreceptors. The paper focuses on the description of the adopted approach and of the implemented software tool in order to control the tactile display. Copyright © 2011 by ASME.

Keywords: HumanComputer Interaction , Material simulation , Multisensory interaction , Selective stimulation , Tactile display

This paper presents a tactile synthesis method to provide roughness and texture coarseness sensations using a selective stimulation approach implemented by a tactile display. Digitizing, elaborating and processing real material surfaces obtain signals. The selection of their frequency range is based on the reactive frequencies of SAI and FAI types receptors. An electro-tactile display provided with a mechanical vibration to stimulate FAII units located at the deeper skin layers has been developed. A SW tool allows to manage selective signals modulation and configuration according to the displayed material. The research aims at overcoming a crucial problem concerning the signals adopted by most electro-tactile displays to stimulate skin mechanoreceptors. The paper focuses on the description of the adopted method and of the implemented software tool to control the tactile display. Preliminary experimentations were carried out to measure the system's latency, accuracy and reliability. Experimental sessions show a promising system response: minimal latency (30ms), good reliability (>98%) and acceptable accuracy (>70%). © 2011 by ASME.

Materials properties simulation by means of haptic devices is one of the most significant issues in the design of new humancomputer interfaces to support virtual prototypes interaction in numerous product design activities. Notwithstanding the several research attempts, a very natural perception of materials has not been achieved yet. We present a novel tactile display. It combines both mechanical and electrotactile approaches to simulate natural tactile sensations. In order to enhance experience acoustic and visual cues are integrated. A signal generation method allows correlating materials properties and simulating signals according to the characteristics of fingertip mechanoreceptors. The final scope is making users perceive the object's surface roughness, slickness and texture coarseness. Research results are the developed simulation method and the detailed design of the whole tactile display. The preliminary prototype is under construction. © 2011 IEEE.

Keywords: 3D interaction , Haptics , multimodal interaction

In this paper, the generalized differential quadrature (GDQ) method is applied to study the dynamic behavior of functionally graded materials (FGMs) and laminated doubly curved shells and panels of revolution with a free-form meridian. The First-order Shear Deformation Theory (FSDT) is used to analyze the above mentioned moderately thick structural elements. In order to include the effect of the initial curvature a generalization of the ReissnerMindlin theory, proposed by Toorani and Lakis, is adopted. The governing equations of motion, written in terms of stress resultants, are expressed as functions of five kinematic parameters, by using the constitutive and kinematic relationships. The solution is given in terms of generalized displacement components of points lying on the middle surface of the shell. Simple Rational Bézier curves are used to define the meridian curve of the revolution structures. Firstly, the differential quadrature (DQ) rule is introduced to determine the geometric parameters of the structures with a free-form meridian. Secondly, the discretization of the system by means of the GDQ technique leads to a standard linear eigenvalue problem, where two independent variables are involved. Results are obtained taking the meridional and circumferential co-ordinates into account, without using the Fourier modal expansion methodology. Comparisons between the ReissnerMindlin and the TooraniLakis theory are presented. Furthermore, GDQ results are compared with those obtained by using commercial programs such as Abaqus, Ansys, Nastran, Straus and Pro/Mechanica. Very good agreement is observed. Finally, different lamination schemes are considered to expand the combination of the two functionally graded four-parameter power-law distributions adopted. The treatment is developed within the theory of linear elasticity, when materials are assumed to be isotropic and inhomogeneous through the lamina thickness direction. A two-constituent functionally graded lamina consists of ceramic and metal those are graded through the lamina thickness. A parametric study is performed to illustrate the influence of the parameters on the mechanical behavior of shell and panel structures considered. © 2011 Elsevier Ltd. All rights reserved.

Keywords: Doubly curved shells of revolution , Free vibrations , Functionally graded materials , Generalized differential quadrature method , Laminated composite shells , Rational Bézier curves

This paper presents a multi-physic modeling of an electromechanical energy scavenging device able to supply energy inside car tires for wireless sensors. A permanent magnet, connected to the inner liner of a tire, is accelerated along a guide by the tire deformation during car motion; by interacting with coils it generates a power which is conditioned by a proper electronic interfaced to an external load. The original approach implemented in this kind of device is the nonlinear dynamic properties designed and controlled: adaptive resonance in function of car velocity is optimized for increasing its global efficiency. The energy conversion process takes into account the simulation of different phenomena such as: non linear dynamic and adaptive resonant behavior of the seismic mass, electromagnetic and magneto-static coupling between moving mass and coils, transfer of the generated power to an external load by means of a nonlinear circuit interface. An integrated model of the cascaded energy steps is developed inside the Simulink/Stateflow environment. A good agreement is found in the comparison between theoretical model and experiments conducted on prototypes produced by means of drawings directly obtained from 3D CAD models. To compare these results to other energy harvesting devices found in Literature, the same device adapted with symmetric configuration is derived. Empirical formulas to measure efficiency are evaluated for this device and compared with Literature results. The accurate modeling of the energy conversion device is a breakthrough in the modeling of these kinds of devices and allows to reach interesting power/volume ratios: small dimensions (about one cubic centimeter) and relatively high power output (more than one milliwatt). © 2011 SAE International.

This paper presents a multi-physic modeling of an electromechanical energy scavenging device able to supply energy inside car tires for wireless sensors. A permanent magnet, connected to the inner liner of a tire, is accelerated along a guide by the tire deformation during car motion; by interacting with coils it generates a power which is conditioned by a proper electronic interfaced to an external load. The original approach implemented in this kind of device is the nonlinear dynamic properties designed and controlled: adaptive resonance in function of car velocity is optimized for increasing its global efficiency. The energy conversion process takes into account the simulation of different phenomena such as: non linear dynamic and adaptive resonant behavior of the seismic mass, electromagnetic and magneto-static coupling between moving mass and coils, transfer of the generated power to an external load by means of a nonlinear circuit interface. An integrated model of the cascaded energy steps is developed inside the Simulink/Stateflow environment. A good agreement is found in the comparison between theoretical model and experiments conducted on prototypes produced by means of drawings directly obtained from 3D CAD models. To compare these results to other energy harvesting devices found in Literature, the same device adapted with symmetric configuration is derived. Empirical formulas to measure efficiency are evaluated for this device and compared with Literature results. The accurate modeling of the energy conversion device is a breakthrough in the modeling of these kinds of devices and allows to reach interesting power/volume ratios: small dimensions (about one cubic centimeter) and relatively high power output (more than one milliwatt). Copyright © 2011 SAE International.