Virtual prototyping and digital twin

The design of industrial products is a process based on the collaboration of different experts with different technical knowledge and backgrounds. For example during the first stages of the design process the shape of the product is defined by designers from the aesthetic point of view. Late in the process the same shape is analyzed by engineers and refined. Today, due to the use of different specific computer-aided tools, it happens that sometimes the representation of the product made by the different members of the design team is not the same. Then the different backgrounds of the members of the team may cause the use of different languages and concepts to represent the same information. So the exchange of information in the design team can become the bottleneck of the entire design process. This paper describes an annotation tool integrated in a Mixed Reality environment whose aim is to try to reduce the time and augment the level of collaboration. The Mixed Reality environment, in which the two phases of the definition and analysis of the shape have been integrated, makes use of a semi-immersive visualization system and some haptic technologies. The application has been validated through some user tests and the results have highlighted the potentialities of the entire application in terms of collaboration and the limits in terms interaction that are basically due to the fact that some users are still not familiar with these technologies. © Organizing Committee of TMCE 2010 Symposium.

Keywords: Annotation systems , Collaborative design and engineering , Knowledge management , Virtual prototyping

During product development, usability tests allow the investigation of product performance in terms of effectiveness and user satisfaction. Virtual Reality (VR) systems provide new modes of Human-Computer Interaction (HCI) that can support usability testing at the early design stages by adopting virtual prototypes to simulate product experience. The problem is that only posture and occlusion parameters can be easily measured while the emotional and affective dimension is difficult to be assessed. In this context, the present paper focuses on two objectives. Firstly, it aims at investigating which product attributes stimulate affective user response by defining a structured protocol to analyze how sample users experience product attributes determining affordance and synaesthesia qualities. Then, real and virtual environments are compared in order to address VR systems improvements. Consequently, the second goal is to define a new VR-based environment for usability testing by considering a proper set of existing technologies integrated with a proposed multi-sensorial system for materials texture and roughness perception. Protocol experimentations are carried out in household appliances. © 2010 Taylor & Francis Group.

The importance of Human-Centered Design (HCD) drives research toward the development of new UIs (User Interfaces) in order to predict human interaction with products at the early design stages. Virtual Reality (VR) allows carrying out usability tests on virtual prototypes to investigate users' cognitive and affective response. Application problems regard with the reproduction of synaesthesia qualities in order to make the information processing similar to the one obtained by real sensory stimulation. While visualization technologies seem to be mature enough to overcome the above mentioned limitation, tactile devices are still far from properly simulating materials properties. In this context, the present work aims at structuring and applying a systematic approach to conceive, define and develop a novel VR-based technology, called IperTouch. The goal is to stimulate the skin mechanoreceptors to generate a meaningful tactile sensation about materials softness, friction and roughness. The system can be also integrated with imaging and sound technologies to create a multi-sensorial product experience. The preliminary architecture results from the analysis of human tactile perception and the benchmark of available simulation devices and techniques. This paper contributes to discuss current issues of existing VR-based technologies in supporting HCD applications and to address technical developments toward the creation of a reliable system for texture perception. Keywords: Human-Centered Design (HCD), Human-Computer Interaction (HCI), virtual touch, material simulation, product experience. Copyright © 2010 by ASME.

Virtual prototyping (VP) of complex machines requires the realistic representation of components to perform robust analyses and simulations. In many cases, machines are an assembly of rigid and flexible components. Although modern three-dimensional CAD systems can be considered powerful tools for modelling solids or surfaces representing rigid bodies, they are not adequate to model soft material components, especially a realistic visualisation of physical behaviour. This drawback motivated the present research work. In particular, this paper describes an approach and the related knowledge-based software system (FlexSim) developed to create virtual prototypes facilitating product development in cases of flexible parts like cables, pipes and wires. The resulting VP tool integrates the CAD technology and the dedicated structural simulation methods to automatically model and validate three-dimensional functional sub-groups having flexible parts. The system application is shown on metallic reinforced elastomer hoses used for hydraulic power transmissions. For this purpose, a finite-element approach has been implemented to find hose configurations for given boundary conditions determined by mounting positions. Pipe fittings are selected and automatically assembled and the optimal hose length and its ideal spatial disposition are calculated. Simulations of behaviour allow the rapid optimisation of a solution. The system has been tested on agricultural harvest machines and mining equipment, which widely employ hydraulic transmissions for moving groups of components. As a result, the number of physical prototypes, the lead-time due to the trial-and-error activities and the product development costs can be significantly reduced. © 2010 Taylor & Francis.

Keywords: Flexible parts design , Knowledge-based systems , Simulation , Virtual prototype

3D CAD systems are powerful tools for modelling rigid bodies but they are not adequate in order to model flexible material components, especially if a realistic simulation of physical behaviour is required as in virtual prototyping. This paper describes the methodology used to develop a knowledge-based system in order to automatically create virtual prototypes of uniaxial flexible components like cables, pipes and wires. The method has been translated in an operative design software system for metallic-reinforced elastomer hoses. The resulting VP tool integrates the 3D CAD technology and suitable structural simulation methods. The robustness of software system has been verified and errors are assessed. A dedicated experimental set-up has been realised in order to compare the virtual results with the real component behaviour. The system has been applied in the design of multifunctional agricultural machines showing reduction of physical prototypes and the lead-time due. © 2010 Inderscience Enterprises Ltd.

Keywords: fem simulation , flexible components design and modelling , knowledge-based design , virtual prototyping

This paper presents a multi-physic modeling of an electromechanical energy scavenging device. A permanent magnet, connected to the inner liner of a tyre, is accelerated along a guide by the tyre 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 energy conversion process takes into account the simulation of different phenomena like: dynamic behavior of the seismic mass, electromagnetic 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 environment. A good agreement is found in the comparison between theoretical model and experiments. 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). © 2006 IEEE.

Keywords: Adaptive resonance , electro-mechanical device , energy scavenger

The paper discusses a gearbox design method based on an optimization algorithm coupled to a full integrated tool to draw 3D virtual models, in order to verify both functionality and design. The aim of this activity is to explain how the state of the art of the gear design may be implemented through an optimization software for the geometrical parameters selection of helical gears of a manual transmission, starting from torque and speed time-histories, the required set of gear ratios and the material properties. This approach can be useful in order to use either the experimental acquisitions or the simulation results to verify or design all of the single gear pairs that compose a gearbox. Genetic algorithm methods are applied to solve the optimization problems of gears design, due to their capabilities of managing objective functions discontinuous, non-differentiable, stochastic, or highly non-linear. The final design tool, implemented in Matlab® environment, is based on the calculation of load capacity of helical gears, including the computation of tooth bending strength, of surface durability (pitting) and the estimation of service life under variable load, as suggested by International Standards. An automated macro procedure for Solidworks® interacts with the Matlab® environment to get the dimensional parameters of each gear and produces the models of each gear and their assembly. Copyright © 2010 SAE International.

VR (Virtual Reality) is a powerful tool for the simulation of virtual prototypes, because it allows engineers to enhance the analysis and validation of the digital product before manufacturing any physical mock-up. Unfortunately, VR software tools are not able to fully simulate the behaviour of a virtual product, because they are mainly conceived to reproduce the visual appearance of the product: the functional simulation is limited to basic behaviours related to the animation of the objects in the virtual world (e.g.: part movements). This paper describes an innovative approach to create functional behaviour simulations in VR using the same models and the same software employed by the engineers in the design phase. Our approach is based on the run-time connection between the VR software and the simulators used for product design and analysis. This means that there is no need to write code for describing the product behaviour, and any modification done on the behaviour models is immediately testable in VR. It is apparent that these advantages allow to reduce the time needed to implement the virtual prototyping, thus achieving a more efficient design process. © Organizing Committee of TMCE 2010 Symposium.

Keywords: Finite state machine , Functional behaviour simulation , Interactive virtual prototype , Product design evaluation

The use of Mixed Reality in the product development process is emerging as a promising solution that combines the advantages of virtual and rapid prototyping. A mixed prototype is usually based on a physical mock-up on which the visual appearance of the product is superimposed thanks to the augmented reality technologies. An open issue in mixed prototyping is the reduction of time and efforts required to generate and update the behaviour model of the product. This paper presents a Mixed Reality environment in which the product behaviour is simulated using the same models and the same software employed by the engineers in the design phase. This approach guarantees the reliability of the simulation and allows a strong reduction of the time needed to develop the digital prototype. Moreover the paper presents an innovative technique, specifically studied for the simulation of electrical appliances, that aims to make the user able to naturally interact with the mixed prototype. This technique is able to manage the occlusion between real and virtual objects and the interpretation of the user's gestures while he/she is interacting with the elements of the product interface. The novelty of the technique is that it does not require any specific device like data-gloves or tracking systems. © 2010 by ASME.

The design and implementation of a PLM solution in a cross-company environment is a complex and labour intensive operation, which is often coupled with a Business Process Re-engineering (BPR) project to better deploy technologies as well as methodologies and to target the system implementation on the real company needs. Enterprise Modelling (EM) languages are typically used to collect and share process knowledge among the BPR participants. Plenty of techniques are actually available at this scope and it is not always easy to understand how to select and use them in the different steps of re-engineering. The main purpose of this paper is to perform a qualitative analysis of three well known EM languages (IDEF, UML and ARIS) and to propose a new methodology, based on their integrated use, supporting BPR efforts in the Product Development domain. © 2009 Elsevier B.V. All rights reserved.

Keywords: ARIS , Business Process Re-engineering , Enterprise Modelling , IDEF , UML

The present paper deals with the manufacturing process of a railway carriage. In the first part of the paper, the authors focus on a "virtual railway factory" that uses a very innovative assembly cycle, if compared to the traditional manufacturing processes in the railway field. The case study refers to a railway carriage consisting of four modules, that are singularly set up of furnishings and other systems in dedicated workplaces. On one hand, the virtual simulation has highlighted several critical aspects to be improved, in order to achieve a greater feasibility and to reduce time and cost. On the other hand, the designers have been able to evaluate the movements of the parts and the assembly sequences of the components, by considering each geometric, functional and technological constraint and also some safety requirements. The second part of the paper deals with the simulation of the assembling operations and the analysis of tolerance chains, which have been performed through a Computer Aided Tolerancing system. In particular, the precision requirements have been also evaluated and we have compared the accumulation of dimensional and geometric deviations when using both rivets and traditional welds to fasten the modules. © 2009 Springer-Verlag.

Keywords: Computer Aided Tolerancing , Train design , Virtual manufacturing

In this paper, an overall description of the design of a robotic hand is discussed, with particular attention to the required sensory subsystem, its integration within the mechanical structure of the hand and the required control architecture. Different solutions for the joint configuration and the structure of the tendon network adopted for the transmission system are present together with three types of sensors applied on the finger and on the actuators. The integrated design of the hand finger and the sensors is reported and the motivations leading to this particular implementation are thoroughly addressed, taking into account both the mechanical constraints and the control requirements.

Keywords: Robot control , Robotic design , Robotic hands , Sensor systems , Sensors integration

The interest in actuators based on dielectric elastomer films as a promising technology in robotic and mechatronic applications is increasing. The overall actuator performances are influenced by the design of both the active film and the film supporting frame. This paper presents a single-acting actuator which is capable of supplying a constant force over a given range of motion. The actuator is obtained by coupling a rectangular film of silicone dielectric elastomer with a monolithic frame designed to suitably modify the force generated by the dielectric elastomer film. The frame is a fully compliant mechanism whose main structural parameters are calculated using a pseudo-rigid-body model and then verified by finite element analysis. Simulations show promising performance of the proposed actuator. © 2008 by ASME.

A fully mechanical infinitely variable transmission (1VT) based on the use of an oscillating inertia is described. The system includes a four-bar linkage mechanism, an epicyclic gear train and a pair of one-way clutches. The proposed IVT can be used in place of both gear-box and clutch in self-propelled vehicles. A basic model is used for a first attempt sizing of the transmission kinematic parameters. A more accurate model, achieved using Bond Graphs, is used to investigate the dynamic effect of inertias, one-way clutch compliance, and minor design changes in the kinematic parameters. Finally, simulations compare the behavior of a car fitted with a manual gear-box and the same car fitted with the proposed IVT. © 2008 by ASME.

The interest in actuators based on dielectric elastomer films as a promising technology in robotic and mechatronic applications is increasing. The overall actuator performances are influenced by the design of both the active film and the film supporting frame. This paper presents a single-acting actuator, which is capable ofsupplying a constant force over a given range of motion. The actuator is obtained by coupling a rectangular film of silicone dielectric elastomer with a monolithic frame designed to suitably modify the force generated by the dielectric elastomer film. The frame is a fully compliant mechanism whose main structural parameters are calculated using a pseudo-rigid-body model and then verified by finite element analysis. Simulations show promising performance of the proposed actuator. © 2009 by ASME.

In this paper, an overall description of the design of a robotic hand is discussed, with particular attention to the required sensory subsystem, its integration within the mechanical structure of the hand and the required control architecture. Different solutions for the joint configuration and the structure of the tendon network adopted for the transmission system are present together with three types of sensors applied on the finger and on the actuators. The integrated design of the hand finger and the sensors is reported and the motivations leading to this particular implementation are thoroughly addressed, taking into account both the mechanical constraints and the control requirements.

Keywords: Robot control , Robotic design , Robotic hands , Sensor systems , Sensors integration

A novel mathematical procedure is proposed, which makes it possible to optimize lozenge-shaped dielectric-elastomer-based linear actuators for known materials and desired force/stroke requirements. Simulation results are provided which both demonstrate the efficacy of the novel procedure with respect to traditional design approaches and show that simpler, cheaper, lighter and better- behaved lozenge-shaped actuators can be conceived which do not require any integration of compliant frame elements. © 2009 Springer-Verlag Berlin Heidelberg.

The design of complex industrial products requires more knowledge than the one that a single person can possess. A successful industrial design entails a collaborative activity between designers and engineers during which they share their specialized knowledge accepting and interpreting their points of view through a multi-disciplinary and collaborative methodology. In particular, this paper focuses on issues related to the knowledge creation, management and enrichment for industrial collaborative design in virtual environment. The idea is to endow the virtual environment, used to create the 3D models and to carry out the analysis, with a knowledge management (KM) module able to gather information about different versions of the product and simulation analysis data. Moreover, this KM module includes an annotation tool used to support annotation-based collaboration between designers and engineers through which they can exchange impressions, ideas, and comments in order to achieve a shared solution about an industrial design issue. © 2009 Springer-Verlag Berlin Heidelberg.

In the present study, the authors performed a dynamic analysis of the desmodromic timing system, where the valve lifter is realized by conjugate cams, using a methodology of modal synthesis to examine the effects of the deformability of the principal parts, and evaluating the deformations and vibrations of the components under various operating conditions. With this aim, a virtual 3D model and a multibody calculation program were used in a concentrated parameter model, requiring the choice of numerous parameters that greatly affect the results of the analysis. It was therefore important that, within the variability range of these parameters, the values adopted rendered the behavior of the analytical model as close as possible to that of the real system. Finally, the need to evaluate some of the more important aspects of the dynamic system (such as values of clearances, stiffnesses and damping at contacts, and stiffnesses and damping of shafts and belt) made it necessary to validate the model through comparison with experimental trials conducted to determine the valve motion and to measure the strain on the distribution belt.

Keywords: Desmodromic timing system , Dynamics , Flexible bodies , Modal synthesis

Recent analyses on the uninhabited aerial vehicle (UAV) accidents revealed that several kinds of human-system control problems occur in current UAV missions. Therefore, a design of the man-machine interface that allows for an efficient and effective interaction between the operator and the remote vehicle becomes one of the challenges in the development of more reliable UAVs. This paper presents a first implementation of an advanced interface for UAV ground control station based on a touch screen, a 3D virtual display, and an audio feedback message generator. The touch screen is used to send high level commands to the vehicle, the 3D virtual display provides a stereoscopic and augmented visualization of the complex scenario in which the vehicle operates, and the audio feedback message generator informs the operator about any change in operational scenario. The hardware/software architecture of the interface also includes a planning algorithm and a generic vehicle model. The interface has been tested by simulating several UAV missions. The results have shown that the interface requires an adequate level of workload to command the vehicle and allows the operator to build a good level of awareness of the state of the vehicle under his or her control, as well as of the environment in which it operates. © 2009 by the Massachusetts Institute of Technology.