Product design and engineering

Due to the growing interest in innovation issues, support for suitable problem definition is increasingly important and desired, focusing on the identification of the right direction of work without getting lost on useless roads [1]. This work presents a set of rules, conceived by the authors to better define the right reformulation of the initial problem. Most of the philosophical reflections about the concept used to build this procedure are presented. Particular attention is focused on the definition of the exact zone of the critical element to work on, in a specific and precise instant of time. Time and space ontologies, and an historical excursus about operative time, are accompanied by many technical examples in order to provide a deep awareness about classical problem solving steps, already present in ARIZ 85C but used in a different way. © 2011 Published by Elsevier Ltd.

Keywords: Operative time , Operative zone , Problem reformulation , Psychological inertia , TRIZ

In this work a method for identifying the key points and supporting an eco-design activity for SMEs is presented. Amongst the different concurrent approaches in the literature, Active Innovation Management (AIM), is currently developing, jointly with the University of Bergamo, an integrated approach based on Life Cycle Assessment (LCA) and TRIZ eco-guidelines. The main goal of this integration is to simplify the eco-design approach in order to make it accessible to European small medium enterprises (SMEs). All activities are part of a European Community (EC) project called REMake. The proposed method consists of a preliminary scan of a given product or process in order to disclose all involved flows of material and energy, and to assess its environmental impact by means of traditional LCA indexes. The hot points of the process are then identified adding to classical LCA criteria a brand new index, called the "IFR index", conceived from the TRIZ "Ideal System" concept. Once key points are identified, a set of 330 eco-design guidelines are introduced to develop alternatives and modifications to the given system with the aim of providing a lower global environmental impact. A first version of those guidelines [3, 8, and 9] was conceived starting from the eight natural Laws of Evolution of Technical System (LTSE) introduced by Altshuller [10]. Here an extended version allows the user to work in each phase of the product life cycle, and integrates other TRIZ tools and best eco-practices. Preliminary results of the application in SMEs will be presented with a case study concerning a textile home-furnishings and bed linen painting company. © 2011 Published by Elsevier Ltd.

Model-based definition (MBD) is a new strategy of product lifecycle management (PLM) based on computer-aided design (CAD) models transition from simple gatherers of geometrical data to comprehensive sources of information for the overall product lifecycle. With MBD, most of the data related to a product are structured inside native CAD models, instead of being scattered in different forms through the PLM database. MBD aims are suppression of redundant documents and drawings, better data consistency, better product/process virtualization, and better support for all computer-aided technologies tasks under engineering and manufacturing disciplines. Developing MBD today, for a medium- to large-sized company in the automotive and aerospace sectors, deals primarily with its fundamentals: data structures. Companies need a common approach to structure data in reusable, unified forms inside native three-dimensional CAD models. For this reason, this research work has been developed by focusing the attention on a method for supporting the MBD implementation by the use of the quality function deployment approach. In order to analyze the efficacy of the proposed approach, it has been validated in the aerospace and defense domain where companies deal with complex products, characterized by a large amount of data exchange, and where collaborative design is a fundamental practice. © 2010 Springer-Verlag London Limited.

Keywords: Computer-aided design , Model-based definition , Paperless engineering , Product lifecycle management , Product virtualization

Design can be defined as the human activity aimed to conceive and develop the "best" constructive solution, capable to perform a given function. In this paper we will present the conception of a data base capable to archive constructive solutions related to a given function. The aim of this DB is to be the starting point of the design process and a useful tool for the designer. The structure of this database has been conceived starting from the schema of the design process, in order to store a functional model derived from several functional representations available in the technical literature.

Keywords: Design method , Functional modeling , Knowledge storage

Bolted joints involving composite plates used to be almost entirely dedicated to aerospace applications. As the need for energy conservation has increased, the field of composite bolted joints has found new applications in ground armoured vehicles. Thick panels able to withstand large in-plane and impact loads are critical. The present investigation evaluates the interior strain field, through the thickness, of a composite plate connected to an aluminium panel with a single-lap bolted joint. The area of interest is the bearing plane region close to the hole because of the presence of stress concentrations that heavily modify the stress field. Experimental data for the bolted joint were recorded by fibre-optic strain gauges that were embedded in the bearing plane of the composite plate. Numerical analyses were performed using ANSYS as a pre-processor and LS-DYNA as a solver. The overall goal was to evaluate the magnitude of contact strains around the hole and through the thickness of the composite. These values were analysed and compared with the finite-element method results: the finite-element analysis correlated reasonably well with the experiments. An investigation of error causes was also carried out, in particular to evaluate the influence of incorrect gauge positioning and the effect of friction coefficients. General design considerations were finally provided, based on the complete three-dimensional finite-element analysis.

Keywords: ANSYS , bolted joint , composite materials , FEM , fibre-optic strain gauge (FOSG) , LS-DYNA

This work concerns the usability assessment of two control devices for a wheelchair-mounted robot manipulator aimed at assisting physical disabled people. The assessment of the usability is a crucial issue for the design of such products, since they communicate with their users not only through their shape, but especially through their control interfaces. In a first phase, the study focuses on defining a synthetic usability index on the basis of the methodologies currently in use. In a second phase, some experiments in Virtual Reality (VR) have been carried out. The use of VR technologies for the collection of the experimental data has been fundamental in terms of safety, costs and repeatability of the tests. Another important result has been the reduction of the sources of noise, thanks to preliminary simulations in VR and non-invasive questionnaires and interviews for capturing the subjective perceptions of users. Finally, it is worth noticing that the developed model may show its validity also in evaluating the usability of other products. Indeed, it provides a basis for a more extensive use of VR experiments for evaluating different design solutions in terms of global usability requirements. © Organizing Committee of TMCE 2010 Symposium.

Keywords: Analytic Hierarchy Process (AHP) , Assistive robotics , Participatory design , Usability index , Virtual reality experiments

In this paper the optimization process of a new High Energy Absorption Rear Underrun Protective Device called HEARUPD is discussed. The main objectives of the HEARUPD design optimization process have been related to the reduction in car decelerations (high crashworthiness) and avoiding the car underrun (high structure stability). In the implemented optimization process, the crash between an economy car (GEO Metro) and the rear part of a truck has been simulated by numerical models. A linear function of the decelerations measured on the car has been used as objective to minimize, the main dimensional values of the rear underrun protective device, instead, have been chosen as design variables. The Simplex Method has been used as optimization technique. At the end, a detailed analysis of the optimized model has been also performed. The obtained results have shown the HEARUPD, in comparison with a reference device, is able to dissipate a higher quantity of energy, reducing both the deceleration peaks and the frontal car crushing. © Organizing Committee of TMCE 2010 Symposium.

Keywords: Crash test , Finite element method analyses , Optimization , Rear underrun protective device , Simplex method , Truck

This paper presents a new 3D design paradigmfor the development of specific custom-fit products, such as the soft socket of prostheses for lower limb amputees. It is centered on the digitalmodel of the human body and, contrarily to the traditional process almost manually based, it considers the integration of methods and tools coming from different research and application fields: Reverse Engineering, Medical Imaging, Virtual Prototyping, Physics-based Simulation, and Rapid Prototyping. The paper describes the techniques adopted to acquire and create the digital model of the residual limb, the procedure to generate the socket model, the strategy developed for the functional simulation of the socket-stump interaction and, finally, the realization of the physical prototype. Each design step is described with the related problems and the obtained results. Both trans-tibial and trans-femoral amputees have been considered; however, for now the complete process has been validated for trans-tibial prostheses. Major outcomes of the proposed approach stand in a better quality of the final product, in a shorter involvement of the amputee implying a lower psychological impact, in a limited use of physical prototypes, and in a shorter development time. Moreover, the resulting paradigm answers to the Collaborative Engineering guidelines by optimizing the interaction between different domains and enhancing their contributions in a homogeneous development framework. © 2010 Elsevier B.V. All rights reserved.

Keywords: Custom-fit products , Human-centric soft product design , Physics-based modeling for soft products , Prosthesis development process

The need for a designer to have a tool able to do motion and constraint analysis, to check for the under-constrained and/or over-constrained status of an assembly, is strategic in a design contest where several changes are made during the design process by using CAD. Traditional kinematic tools provide little information on over-constraints at 3D level. Screw theory has been already used in mechanical assemblies, in a top-down design, to do motion and constraint analysis. This theory is here used to analyze mechanical assemblies in the contest of a feature-based CAD system. The structure of the CAD assembly is captured and described as assembly graph, similar to Datum Flow Chain, through which the motion or constraint status of any part (in terms of twist and wrench matrices), can be obtained. The underlying algorithm is based on the Kirchoffs rules successfully applied by Davies to mechanisms. How to automatically create the assembly graph, detect the useful loops and then write the loop kinematic equations is described. Three case studies are presented related to CAD assemblies of mechanisms built up in SolidWorks® CAD system by Dassault Systèmes from which assembly constraints have been acquired. Copyright © 2010 by ASME.

In order to overcome the limits due to the fact that homogeneous layers of soft material placed over robotic limbs behave differently with respect to biological models, this paper suggests the adoption of soft covers (pads) with differentiated structure. In particular, it is proposed to divide the allowable pad thickness into two layers: a continuous external layer (skin) and a discontinuous internal layer, so that the overall stiffness can be adjusted by properly shaping the discontinuous layer. The methodology adopted for designing the internal layer is composed of two steps. Firstly, the cover surface is conceptually split into finite elementary triangular sub-regions. Secondly, the internal layer of each triangular element is designed in order to replicate the shape of the non-linear compression law which is typical of endoskeletal structures covered by pulpy tissues. A series of symmetrically-disposed inclined micro-beams is used for the purpose. Once the compression law of each triangular element is known, the overall pad compliance can be modulated by correctly choosing the number and size of the elements composing the pad. Equipment and results of a combined experimental and numerical analysis (FEM) are presented. The results confirm that the proposed concept can be an effective solution when designing soft covers whose behavior need to match the compliance of the biological counterpart. As an example, artificial pads which mimic the human finger behavior are presented. © 2010 by ASME.

The development of safe and dependable robots for physical human-robot interaction is actually changing the way robot are designed introducing several new technological issues. Outstanding examples are the adoption of soft covers and compliant transmissions or the definition of motion control laws that allow a compliant behavior in reaction to possible collisions, while preserving accuracy and performance during the motion in the free space. In this scenario, a growing interest is devoted to the study of variable stiffness joints. With the aim of improving the compactness and the flexibility of existing mechanical solutions, a variable stiffness joint based on the use of compliant flexures is investigated. The proposed concept allows the implementation of a desired stiffness profile and range along with the selection of the maximum joint deflection. In particular, this paper reports a systematic procedure for the synthesis of a fully-compliant mechanism used as a non-linear transmission, together with a preliminary design of the overall joint. © 2010 by ASME.

The majority of soft pads for robotic limbs studied so far were made by visco-elastic polymeric solids whose behavior is significantly influenced by the rate of application of the external loads or displacements. In particular, contact interfaces which are intrinsically visco-elastic are found, for instance, in human fingers and feet or in various robotic devices covered by a compliant surface. An outstanding instance are anthropomorphic hands where time-dependent phenomena profoundly affects the stability and sustainability of the grasp. Alternatively to homogenous solid pads, this paper proposes the use of fluid filled soft structures with differentiated layer design [1] that is the adoption of a single solid material, dividing the overall thickness of the pad into a continuous skin layer coupled with an internal layer having communicating voids. The voids are then hermetically sealed and, in case, filled with fluid. Given the allowable pad thickness, the purpose is to tailor the pad properties to the specific application by 1) selecting a skin material characterized by proper tribological features, 2) designing an inner layer geometry so as to obtain a specific static compliance, 3) filling the pad with a viscous fluid chosen so as to modify time-dependent phenomena and increase damping effects. The proposed concept is validated by designing artificial pads whose viscoelastic properties are either similar or more pronounced when compared to those of the human fingertip. ©2010 IEEE.

Keywords: Experimental analysis , Human fingers , Robotic hands , Soft fingertip design

A fully mechanical, infinitely variable transmission (IVT) 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 IVT can be used in place of both gearbox and clutch in self-propelled vehicles. A mathematical model is presented. Numerical simulations compare the behavior of a car fitted with a manual gearbox and the same car fitted with the IVT.

A novel mathematical procedure is presented, which makes it possible to optimize lozenge-shaped dielectric-elastomer-based linear actuators for known materials and desired force/stroke requirements. Simulation and experimental results are provided which both demonstrate the efficacy of the proposed optimization 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.

Keywords: Dielectric elastomers , Optimal design. , Smart actuators

After a brief reminder about previous work, this paper addresses the dynamic characterization of fluid-filled soft pads for robotic hands. The adopted pad specimens are constituted by a single hyper-elastic material having hardness similar to that of the human thumb. The overall pad thickness is then divided into a continuous skin layer and an internal layer having communicating voids which are hermetically sealed and filled with a viscous fluid. Despite a more complicated design, it has been proven [1-3] that the pads present enhanced compliance and damping properties, a lower thickness and a higher surface hardness when compared to previously published solutions. In addition, a quasi-linear model, frequently used to describe the behavior of soft biological tissues can be applied in order to predict and control the pad interaction with the environment during grasping and manipulation tasks. In particular, the experimental tests necessary to evaluate the parameters which determine the pad dynamic response are described and discussed in detail.

Keywords: Quasi-linear model , Soft fingers , Viscoelasticity

Actuators based on Dielectric Elastomers are a promising technology in robotic and mechatronic applications. The overall actuator performances are influenced by the non-linear and highly coupled electrical and mechanical behavior of the employed materials. To date, the practical electro-mechanical response and controllability of actuators based on Dielectric Elastomers are limited by the inadequacy of the employed driving circuits, which are based on voltage-regulated converters. In this paper, first a novel activation strategy is proposed for Dielectric Elastomer actuators, which is based on a custom electronic driver derived from the flyback transformer topology. Second, two closed-loop controllers employing the proposed electronic driver are presented and compared for the accurate and fast regulation of the position of Dielectric Elastomer actuators. Experimental results are reported which show that the proposed electronic driver outperforms the traditional driving circuits in terms of energy efficiency, fast open-loop actuator activation and good closed-loop actuator controllability. © 2009 Elsevier Ltd. All rights reserved.

Keywords: Dielectric Elastomers , Driving circuits , Position control , Smart actuators

In the last few years, many methodologies of reverse engineering have been proposed for 3D shape measurement using optical systems. All the proposed 3D scanning solutions require user interactions concerning the alignment process of partial measures to reconstruct the complete shape of a target object. This paper presents an innovative solution based on the integration of a robotic arm and an optical stereo system, which minimizes user intervention both in the acquisition and in the reconstruction phases. The procedure is divided into two steps: 1) complete and accurate identification of the integrated system, using optical measurements of a reference surface (calibration process); 2) planning of scanning strategies in order to automatically obtain a complete 3D CAD representation. Results of experimental tests conducted on nominal samples and on industrial contexts are presented and discussed. © 2010 Taylor & Francis Group.

The H.U.S.H. (Harmonization of Urban noise reduction Strategies for Homogeneous action plans) project moves from the evidence that harmonization of noise action planning methods is needed, not only in Italy but also in all the European countries where a former Legislation about noise planning was existing at the moment of Environmental Noise Directive (END) 49/2002/EC adoption. The general aim is harmonizing national noise management standards with END for obtaining homogeneous noise Action Plans, in order to give contribution to the more general need of transposing, implementing and enforcing a common or harmonized environmental legislation among EU countries. Specific aims of the project are the following ones: a) to point out unsolved conflicts among current standards at Regional, National and European level; b) to define common methods for designing strategic and specific solutions; c) to define a new development system (procedures and database) for action planning by testing it in a pilot case; d) to design guidelines in order to build a system for action plan applications supporting Regional, National and European Law reviews. In this paper the results coming out from a specific action of HUSH project carried on by the University of Florence are described. This specific action focuses to build up the geographical data platform for city action planning. To achieve this aim, a few of city Action Plan data platforms - available in Italy and in European countries-were analyzed and compared referring to address the requirements set out by National, Regional and European regulations.

The evolution of olive oil technology is related to research raised to deepen the understanding of biological and biophysical phenomena during the machining process olives, thus allowing the introduction of sensors able to monitoring the parameters and the process according to the characteristics of olives themselves. Current research has identified manufacturing protocols that can enable the achievement levels of product quality required by the market, mainly by reducing the time between collection and processing of olives and raising the technological level of extraction lines. In this context, the present chapter aims to describe the results of a three-years project developed by the PIN-University of Florence (Italy) in collaboration with the Tuscan Regional Agricultural Development, the Florence Commerce Chamber "Laboratorio Chimico Merceologico-Azienda Speciale CCIAA di Firenze" and the SME "TEM" (Toscana Enologica Mori). The chapter will describe the development of an innovative olive oil extraction process, characterized by a series of automatic controls (sensors, Machine Vision systems, etc.) of several agronomical and technological parameters during the extraction phases. This system allows several settings of the extraction process in order to dynamically modify the quality properties of the olive oil extracted. The oil mill is supported by computers and electronics systems (Machine Vision, sensors and Artificial Neural Network based software) that consents (1) the acquisition of data from the raw material, the extracted oil and the process parameters and (2) the development of a series of algorithms able to estimate the olive oil quality before the extraction process has started and to simulate the process. After some experimental campaigns conducted during the harvesting period of years 2005-2008, the devised approach identified the interrelationships between acquired data and quantitative characteristics of the product extracted. Based on the findings of the analysis of experimental data, software has then been implemented and validated. The validation comprises an iterative process that will impose changes to the software, general procedures, the possible amendment of the basic mathematics of the system, the estimate of the error, the statistical analysis of data and the development of new graphical user interfaces. The results of the devised system have been conducted according in force to European Union Rules standards and have been compared with the ones suggested by the literature.

Colour matching between carded and finished fibres is an important challenge for textile industry. The straightforward approach for mixing together some differently coloured fibres in order to obtain a blend of a desired colour is to perform a trial and error approach starting from a given colour recipe and optimizing it with several attempts. Unfortunately, dyeing process so as the carding procedure may result in a carded fibre whose colour is different from the desired one. As a consequence textile companies have to modify the original recipe in order to reduce the gap between the colour of the final product and the desired one. The present work describes a model able to simulate the colour mixing of fibres in order to assess the best recipe. The model consists in two modules: a prediction module predicts the colour of a blend obtained by mixing together several fibres; an optimization module is used to optimize the final recipe. The devised system has been tested for optimizing the recipe of a set of 200 blends. The mean error in predicting the blend colour is about 15 with a variance of 0.165. The time for optimizing the recipe is reduced by 92. Copyright © 2010 Rocco Furferi and Monica Carfagni.