Virtual prototyping and digital twin

In the last decades, research in the orthodontic field has focused on the development of more comfortable and aesthetic appliances such as thermoformed aligners. Aligners have been used in orthodontics since the mid 20-century. Nonetheless, there is still not enough knowledge about how they interact with teeth. This paper is focused on the development of a Finite Element Method (FEM) model to be used in the optimization process of geometrical attributes of removable aligners. The presented method integrates Cone Beam Computed Tomography (CBCT) data and optical data in order to obtain a customized model of the dental structures, which include both crown and root shapes. The digital simulation has been focused on analyzing the behavior of three upper frontal teeth. Moreover, the analyses have been carried out by using different aligners' thicknesses with the support of composite structures polymerized on teeth surfaces while simulating a 2 degrees rotation of an upper central incisor.

This paper describes an efficient methodology based on the co-simulation between several software tools that has been developed to drive and increase the dynamic behavior of a Desktop Mechatronic Interface (DMI) for shape rendering. The co-simulation is performed by using a multi-body software, which is linked to MATLAB/Simulink. With the multi-body software the virtual simulation of the DMI is performed in order to sense the rotation angles of the virtual servo-actuators. By using this interaction it is possible to control the real servo-actuators presented in the DMI. In addition, through this methodology it is possible to perform experimental simulation in kinematics, dynamics and control of the DMI. A collision approach is presented taking into account both, friction and restitution coefficients which are required in the virtual simulation of the DMI. Simulation results show that the co-simulation platform is established successfully.

The paper describes the design and preliminary virtual testing of OSHap, an open-source low cost 2DOF haptic interface. The aim the research is to create a mechatronic platform for haptic interaction based mainly on cheap and open source components. The results will be distributed freely in order to provide guidelines for expert users to develop their own haptic interface. Both the mechanical design philosophy and the control electronics are hereby discussed together with a preliminary testing made by using virtual prototyping tools. The kinematic layout is based on a serial double joint scheme. This choice is claimed to be the less expensive one, inasmuch as tolerances do not have to be narrow as for the parallel systems. The system also allows future users to tune dimensions (and relative workspace) easily. The interface is admittance controlled for maximizing the transparency with low cost drives. The device is based on the Intel Galileo open-source development board: this board embeds a powerful chip-sets that enables us to perform real-time 2DOF control tasks that are hardly reachable with the most common open source electronic platforms. All the choices listed above are discussed and evaluated, with focus on performance-to-cost ratio.

The objective of the paper is to present a case study to exploit interactive Virtual Prototypes (iVPs) for investigating the way humans experience products. This method can be used for "prototyping" new product experiences, for monitoring users' emotional reactions during the interaction and finally, for practically redesigning these experiences on the basis of the users' feedback. Products considered here are domestic appliances, where the experience consists of the interaction with their physical interfaces.

In the product development process one of the crucial phases is the evaluation of the design of the product that must satisfy the marketing targets based on the users' needs analysis. It is commonly acknowledged that a product is successful if people like and buy it. In the phase of ideation of a new product, it is paramount to test functionality and performances as well as the users' appreciation and feeling towards the new product. More specifically, in the case of consumer products characterised by a plurality of offers, interaction and experience should be addressed in addition to function and aesthetics in the user studies. Recent research has focused on the study of the user's emotional reaction when interacting and experiencing products, which is correlated with the global appreciation of the product and of its attributes. This paper presents an emotional engineering methodology using interactive virtual prototyping for evaluating the user experience and the emotional response with newly designed products early in the development process. The methodology suggests a way to optimise those aspects at the product concept phase. © 2014 © 2014 Taylor & Francis.

Keywords: emotional engineering , product experience , virtual prototyping

Designing physical interfaces, like the doors of consumer products, able to elicit a positive experience when interacting with them, is now becoming a key priority for design teams. One of the main difficulties of this activity consists of translating all the qualitative perceptual feedback that can be captured from the customers into quantitative specifications. Performing this translation is not an easy task since there are still no effective tools, methodologies or approaches able to guide designers in accomplishing this goal. To overcome this lack a reverse engineering-based approach is proposed. This one guides designers towards the modelling, parameterisation and reproduction of the behaviour of the product interface to be redesigned, within a multisensory virtual environment. The intent is to let the user experience different behaviours in order to ask them to identify the desired one or to express preferences for updating it in real-time according to indications provided. At the same time a detailed physics model, built by the designer, is used to convert this desired behaviour, into detailed quantitative design specifications. The method is defined as a reverse engineering one for two main reasons: first the new interaction is derived on the basis of the behaviour of an existing interface, taken as reference, and second a reverse engineering of the user's perceptual preferences is applied to derive new specifications. A case study is discussed to demonstrate the method effectiveness and to highlight its limitations. © 2014 Taylor & Francis.

Keywords: haptics , interactive systems , product experience , reverse engineering , virtual prototyping

This paper presents a new concept of a desktop haptic shape display that allows rendering and exploring virtual surfaces. Such device allows continuous and free hand contact on a developable plastic strip that is actuated by a modular handling system. Each module is based on an absolute positioning approach, which allows controlling the represented trajectory, thus overcoming the limits of relative handling systems. The developed system is able to manage the elastic behaviour of the strip in terms of bending, twisting and local curvature control. The latter allows us to handle the local tangency of the strip to the rendered trajectory. The absolute approach allows configuring the system with a variable number of modules, so as to customize it according to the application needs. © 2014 IEEE.

Keywords: Curve rendering , Desktop haptic system , Haptic strip , Virtual Prototyping

This paper presents a novel transportable and cost-effective Augmented Reality system developed to support interior design activities in the contract design sector. The main functioning principles and technical information about its implementation are provided to show how this system allows overcoming some of the issues related to the use of the Augmented Reality in interior design activities. The effectiveness of this system is verified through two different testing sessions based on a case study, which relates to the contract design sector. The testing sessions involved many interior designers with the intent of demonstrating the possibility of integrating this Augmented Reality system in the "everyday" interior design practice in the specific context of the contract design. © 2014 CAD Solutions, LLC.

Keywords: augmented reality , interior design , virtual prototyping

In common industrial practice the definition of shapes of styling products is performed by product designers. They usually produce aesthetic shapes by handcrafting scale models made of malleable material like clay, and often expensive physical prototypes are also manufactured. The paper describes a Desktop Mechatronic System (DMS) that has been conceived to support designers in the creation, evaluation and modification of aesthetic virtual shapes. The objective in designing this system is to develop a system allowing a continuous and smooth free hand physical interaction with a virtual shape, which is rendered through a dynamic cross-sectional contour or curve in three-dimensional (3D) space. The DMS is a useful tool for designers, who are not certain about the quality of the shape of the product, and can use it for testing out ideas. The DMS consists of a servo-actuated developable metallic strip, which reproduces 3D cross-sectional contours, which has been devised and implemented by using the Minimal Energy Curve (MEC) spline approach in which the equidistant interpolation points scheme has been adopted to imitate the virtual object created via a Computer Aided Design (CAD) tool on a physical bendable strip-like surface. © 2013 © 2013 Taylor & Francis.

Keywords: 2D cross-section rendering , CAD associativity , desktop mechatronic system , industrial design , virtual prototyping

This paper describes the multidisciplinary optimization of an airship with unconventional configuration. The shape of the airship is based upon two semi-ellipsoids, whose axis ratios can be altered for optimization purpose. The parameters to optimize are volume, ratio between longitudinal and lateral semi-axis, ratio between vertical and lateral semi-axis, percentage of the top surface covered by photovoltaic films, and dimension of the tail. The objective of the optimization is to reduce the mass of the airship by keeping the equilibrium between buoyancy and weight as a constraint, reaching the design speed while maintaining the static longitudinal stability of the vehicle. The mathematical model developed to evaluate airship features includes the computation of the ballonet volume, a weight breakdown, considerations about the energy storage for night operations, the power system, and the stability. Six heuristic optimization strategies have been applied to achieve the best solution; some case studies have been developed, and the final optimal configurations found by algorithms have been analyzed to validate the optimization framework. The approach demonstrates that the heuristic optimization strategies used are good tools for the conceptual design of unconventional airship since this problem requires a multidisciplinary approach and several parameters including aerodynamics, propulsion, mass breakdown, aerostatics, and stability. These parameters are strongly dependent on each other and they must be considered together to obtain an optimum and balanced design.

Hybrid and electric vehicles are taking an increasingly important slice of the market, gaining much interest from major car manufacturers which have decided to invest in this sector, taking as example the pioneers like Toyota. The key factor to hybrid and electric vehicle success is a good overall mileage achieved from the battery back or powertrain. The purpose of this work is to provide a support to design, testing, and development of such vehicles through the implementation of a mathematical model in order to simulate the operation and predict the performance of a generic ground vehicle equipped with either a purely electric or a hybrid-electric type powertrain. The model should enable the user to estimate the impact of various control strategies on mileage range, efficiency, energy consumption, etc. The model should also allow for a significant time to market reduction with all the related benefits in terms of cost etc. A validation is also provided, based on the application of this tool on a so-called micro-car (0.5t GVW class). Thanks to a joint research project with the manufacturer it has been possible to compare model results with real-world data directly obtained during road testing with the help of a data acquisition system. © 2014 The Korean Society of Automotive Engineers and Springer-Verlag Berlin Heidelberg.

Keywords: Electric vehicle , Hybrid electric vehicle , Mathematical modelling , Performance prediction

It is well known that vehicle slip angle is one of the most difficult parameters to measure on a vehicle during testing or racing activities. Moreover, the appropriate sensor is very expensive and it is often difficult to fit to a car, especially on race cars. We propose here a strategy to eliminate the need for this sensor by using a mathematical tool which gives a good estimation of the vehicle slip angle. A single-track car model, coupled with an extended Kalman filter, was used in order to achieve the result. Moreover, a tuning procedure is proposed that takes into consideration both nonlinear and saturation characteristics typical of vehicle lateral dynamics. The effectiveness of the proposed algorithm has been proven by both simulation results and real-world data. © 2014 Taylor & Francis.

Keywords: analytic model , extended Kalman filter , real-word validation , tyre modelling , vehicle dynamics , vehicle slip angle

Nowadays, electric vehicles fill a relevant car market share. The Li-Ion batteries currently represent the best solution in term of environmental impact and performance. Thermal management for Li-Ion batteries is a very interesting topic, since high temperatures accelerate degradation rate of a cell and compromise its safety level. The battery thermal modeling can be quite challenging. The proposed approach describes a methodology to simulate different thermal management algorithms in order to obtain an uniform temperature distribution in a Li-Ion battery pack. A test case has been developed where the application of an thermal algorithm has been analyzed through CFD simulations.

Keywords: CFD , Hybrid electric vehicle , Li-ion battery , Simulation , Thermal management , Virtual prototyping

An important issue in the mechanical industry is the reduction of the time to market, in order to meet quickly the customer needs. This goal is very important for SMEs that produce small lots of customized products. In the context of greenhouse gas emissions reduction, vehicles powered by electric motors seem to be the most suitable alternative to the traditional internal combustion engine vehicles. The market of customized electric vehicles is a niche market suitable for SMEs. Nowadays, the energy storage system of an electric vehicle powertrain consists of several Li-ion cells arranged in a container called battery pack. Particularly, the battery unit is considered as the most critical component in electric vehicle, because it impacts on performance and life cycle cost. Currently, the design of a battery pack mostly depends on the related market size. A longer design time is expected in the case of a large scale production. While a small customized production requires more agility and velocity in the design process. The proposed research focuses on a design methodology to support the designer in the evaluation of the battery thermal behavior. This work has been applied in the context of a customized small production. As test case, an urban electric light commercial vehicle has been analyzed. The designed battery layout has been evaluated and simulated using virtual prototyping tools. A cooling configuration has been analyzed and then prototyped in a physical vehicle. The virtual thermal behavior of a Li-ion battery has been validated at the test bench. The real operational conditions have been analyzed reproducing several ECE-15 driving cycles and many acceleration runs at different load values. Thermocouples have measured the temperature values during the physical experiments, in order to validate the analytical thermal profile evaluated with the proposed design approach.

Nowadays, design processes need of agile and flexible tools and methods to meet market needs and Ecodesign directive in the industry of household appliances. Virtual prototyping techniques are widespread in design processes and practices, in order to reduce the project development lead-time and the cost related to any real physical prototyping. The aim of this paper is the study of a generic modular approach to support the optimization process of simple mechanical parts using virtual prototyping tools and a multi-DOE solving analysis based on virtual experiments. The target is to increase flexibility in design phases. The research context regards the optimization of a blower for cooker hood applications, in order to improve the fluid dynamic efficacy indicator in accordance with EU Ecodesign directive regarding ventilation fans. The increasing of fluid dynamic efficiency is a way to reduce electrical energy consumption during blower operation. Particularly, this paper focuses on the design optimization of an impeller for kitchen hood. The research-work takes into account the optimization of the blade profile. Inlet and outlet fluid-blade angles have been analyzed and discussed. The methodology proposes the study of a set of geometrical parameters through an analysis based on DOE scheduling with virtual experiments. The proposed test case provides a study of two different fan wheel models for the same hood application. Three geometrical parameters have been considered. The DOE objective function fits the maximization of the fluid dynamic efficiency indicator, in order to reduce energy consumptions. A multi-DOE approach has been used to evaluate the best configuration set. Several CFD simulations have been conducted and the resultant impeller configuration has been also validated through physical tests.

Virtual prototyping lacks of application in SME due to the costs of software systems and the necessity of skilled operators. The aim is to improve dripper emitters design process reducing costs. A knowledge base is presented to gather data on products behaviour in terms of experimental data and simulation results for a set of meaningful test cases. Input design parameters were linked to performance indices on the base of the correlations emerged in the analysis. Specifications for a new product can be used to extract similar cases and to define a possible solution in terms of a combination of them.

Keywords: Design of experiments , Drip emitters , Knowledge based engineering , Virtual prototyping

Multimodal sensory stimulation is one of the most important challenges in human-computer interaction. When we want to play a virtual system it is important that the reproduced signals to stimulate the different sensory channels are synchronized with each other. This paper presents the study and implementation of a multimodal stimulation system. The proposed system is a step forwards a previous developed tactile platform (called Ipertouch 1.0). Main novelties regard the introduction of audio and visual feedbacks and signals synchronization. For acoustic stimulation, an auralization algorithm is applied on records of rubbing finger on a given class of material. For visual stimulation, a 3D rendering software is developed. Tests are performed to evaluate the degree of synchronism among the three different sensory channels.

Keywords: acoustic and visual feedback , haptic , multimodal system , synchronism

Nowadays Virtual Prototyping (VP) of robots dynamics is an effective tool to simulate the system behavior and improve the quality of rehabilitation activities. Using a VP software environment, the patients can be visually guided in their actions and the physiotherapist can control the system parameters easily to investigate the patients' performances in real time. In this paper VP concept is introducted to support the use of an upper-limb orthosis and to improve therapeutic efficacy in rehabilitation. The system adopted is a human-worn rehabilitation exoskeleton enhanced with a VP-based application to make therapeutic exercises more accessible while reducing the effort in using the system and managing the therapy. The VP application in particular merges computational musculoskeletal analysis with simplified controls, 3D viewing and real time simulation of the patients' movements. The application has been designed to specifically address the needs of patients and therapists and improve the satisfaction in use of the global system as well as the therpy results. The system validation is based on an ad-hoc evaluation protocol and is carried out by directly involving final users furing rehabilitation sessions. Experimental results demonstrated how VP prototyping effectively support the system use from both patients and physiotherapists: on one hand patients are nove motivated and they learn extract movements faster; on the other hand physiotherapists are supportedin diagnosis and data elaboration, and finally the rehabilitation therapy efficiency is improved.

Haptic simulation of materials is one of the most important challenges in human-computer interaction. A fundamental step to achieve it regards the definition of how human beings can encode the information acquired by different sensorial channels' stimulation. In this context, this paper presents the study, implementation and evaluation of a multi-modal cutaneous feedback device (CFD) for the simulation of material textures. In addition to tactile stimulation, two further sensory components (e.g. eyesight and hearing) are integrated to support the user to better recognize and discriminate different classes of materials and then, overcome previous identified drawbacks. An experimental protocol is tuned to assess the relevance of each stimulated channel in material texture recognition. Tests are carried out with real and virtual materials. Result comparison is used to validate the proposed approach and verify the realism of simulation. © 2014 Springer International Publishing.

Keywords: Elettrocutaneous feedback , haptic , multi-modal stimulation