Fre ´de ´ric Segonds
email: frederic.segonds@ensam.eu

Fabrice Mantelet

Julien Nelson

Ste ´phane Gaillard

Proposition of a PLM tool to support textile design: A case study applied to the definition of the early stages of design requirements

Introduction

Industries today must face the stakes related to the increasing complexity of their work environment and activities: globalization of their markets, increasing distance between industrial partners, pressures related to costs, proliferation of information, evolutions in the environment, reduced time to market, emergence of codesigning practices involving suppliers. This has gradually led to business process outsourcing, one of the most important changes in design practices in the 2000 decade, experienced by many different professions [START_REF] Pezeshki | Preparing undergraduate mechanical engineering students for the global marketplace-new demands and requirements[END_REF].

PLM (Product Lifecycle Management) is both a company strategy and a specialized information system. It unites the various data and processes related to the product, allowing the various types of professionals involved to share this information within collaborative environments.

Functionalities afforded by PLM tools [START_REF] Maranzana | Collaborative design tools: a comparison between free software and PLM solutions in engineering education[END_REF] generally include managing technical data, and managing configurations and tools in distributed collaborative design. Fig. 1 illustrates current evolutions in the constitution of product development teams. These tend to be increasingly collaborative and virtualized. Indeed, the main existing PLM solutions were designed by 3D CAD software firms, and are therefore used very often in the stages of detailed design of a product. In the early stages of design, these solutions are not very flexible and prove to be unsuitable. Furthermore, the textile industry relies heavily on the use of 2D patterns, and Digital Mock-Ups (DMUs) are not very strongly developed. Despite the fact that editors of PLM solutions tend to propose increasingly evolved software programs, at the time of writing, there exists no clear methodology to define a collaborative tool that is suited to the needs of the textile industry.

The scientific contributions of this paper are: (a) a state of the art of current PLM solutions and their application in the textile industry, (b) the presentation of a case study from the textile industry where we identified the main Intermediary Representations (IRs) used by designers, that are most likely to support collaboration; and (c) the definition and testing of a mockup of a collaborative tool to assist the early stages of design and relying on the IRs mentioned above.

We will first present existing PLM tools as well as their main functionalities. We will then describe a case study in the Devanlay textile company, starting with the analysis of requirements in terms of collaborative tools, up to the specification and testing of a collaborative tool. Our conclusion will focus on the generalizability of the method and of the results obtained. The current climate of economic competition forces businesses to adapt more than ever to the expectations of their customers. Faced with new challenges, practices in textile design have evolved in order to be able to manage projects in new work environments. After presenting a state of the art overview of collaborative tools used in product design and making functional comparison between PLM solutions, our paper proposes a case study for the development and testing of a collaborative platform in the textile industry, focusing on the definition of early stages of design needs. The scientific contributions presented in this paper are a state of the art of current PLM solutions and their application in the field of textile design; and a case study where we will present, define, and test the mock-up of a collaborative tool to assist the early stages, based on identified intermediary representations.

PLM and its implementation in the industry

The evolution of work practices in product design

In this part, we propose a chronological state of the art of the methods applied in the business world in order to improve their competitiveness. These methods, applied in the industrial world, seem to be at the heart of the issue of reducing product development time, which many businesses in the textile industry currently face.

Concurrent engineering

Towards the end of the 1980s and the beginning of the 1990s, two forms of design organization emerged as distinct alternatives: sequential design, which involves carrying out design tasks one after the other, and concurrent engineering, or integrated design [START_REF] Prasad | Concurrent Engineering Fundamentals: Integrated Product and Process Organization[END_REF][START_REF] Sohlenius | Concurrent Engineering[END_REF][START_REF] Winner | The Role of Concurrent Engineering in Weapons System Acquisition[END_REF]. Two of the aspects of Concurrent Engineering (CE) that distinguish it from conventional approaches to product development are cross-functional integration and concurrency. In CE, one must define shared interfaces between the various tasks. Indeed, CE is an approach to product development, in which considerations about product lifecycle processes, from product planning, design, production to delivery, service, and even end-of-life, are all integrated. By carrying out all these tasks in a parallel fashion, it becomes possible to reduce the time and costs of design, but also to improve the quality of products. With the development of Information Technology (IT), CE methods have evolved gradually towards PLM.

PLM

In the early 2000s, PLM emerged as a solution to adapt engineering design to the demands of globalization. Indeed, as PLM addresses the entire lifecycle of the product, it has a crossfunctional nature and deals closely with the way a company runs [START_REF] Garetti | Organisational change and knowledge management in PLM implementation[END_REF]. Collaborative design has been the subject of numerous studies. With the development of PDM (Product Data Management), PLM (Product Lifecycle Management) and associated workflows, software firms have proposed solutions to the everyday problems of engineering design departments (versioning of documents, naming etc.). Product Lifecycle Management aims to cover all the stages of product development, by integrating the processes and people taking part in the project [START_REF] Schuh | Process oriented framework to support PLM next term implementation[END_REF]. This concept is generally used on industrial products. For Amann [START_REF] Amann | Product Lifecycle Management: Empowering the Future of Business[END_REF], over the past several years, PLM has emerged as a term to describe a business approach for the creation, management, and use of product-associated intellectual capital and information throughout the product lifecycle. Thus, PLM is an approach in which processes are just as important as data, or even more so. The PLM approach can be viewed as a trend towards a full integration of all software tools taking part in design and operational activities during a product's lifecycle [START_REF] Garetti | Organisational change and knowledge management in PLM implementation[END_REF][START_REF] Amann | Product Lifecycle Management: Empowering the Future of Business[END_REF]. Therefore, PLM software packages need product data management systems, as well as synchronous and asynchronous, local and remote collaboration tools and if necessary, a digital infrastructure allowing exchanges between software programs.

Existing PLM solutions and related functionalities

Current PLM tools offer functionalities that can be found in most of software solutions [START_REF] Duigou | Framework for Product Lifecycle Management in-tegration in small and medium enterprises networks[END_REF]. These can be classified into three main categories: Product Data Management (PDM), configuration management, and distributed design tools.

The main functionalities found in PDM tools are as follows [START_REF] Maranzana | Collaborative design tools: a comparison between free software and PLM solutions in engineering education[END_REF]:

Access rights management: depending on the user's clearance level, (s)he given access to information contained within the PLM system.

Vaults: datasets and related documents are stored onto a server called a vault, as opposed to being stored locally on the user's computer. Document visualization: users are able to rapidly visualize documents in various formats, without owning the application that corresponds to a particular file format. Check-out and check-in: this functionality allows users to check out a document in order to ensure that no other user working on the document at the same time may alter it. Document versioning: several versions of the same document may be archived.

States: various states are associated with each document. These help define their level of maturity: creation, validation, obsolescence, etc. Workflows: these systems make it possible to model processes and to automate actions. These systems are mostly used in validation processes for documents and technical data.

Configuration management consists in controlling information related to product structure, especially by breaking it down into elementary parts, and adding information related to their functional and physical characteristics [START_REF] Zina | Generic modeling and configuration management in product lifecycle management[END_REF]. The ISO 10007 standard [12] includes recommendations for using configuration management in the industry. It provides the detailed process, organization and procedures for configuration management. According to this standard, this configuration management is an integral part of PLM. It provides a clear vision of the configuration state associated with a product or project, as well as their evolutions by guaranteeing total traceability [12]. Distributed design tools [START_REF] Johansen | Groupware Computer Support for Business Teams[END_REF] allow users to share a screen, to remotely gain control over another user's workstation, and to exchange instant messages. They also allow the use of a webcam to visualize a colleague, or of VoIP to talk with him/her.

PLM is currently evolving towards PLM 2.0, which takes advantage of the intelligence that is collectively generated by online communities. In this view, all users may imagine, share, and experiment with 3D products. Current software editors follow a global approach when designing information systems in companies. In other words, such systems aim to structure collaborative work at every stage in the product life cycle; to cater for the needs of every profession involved in the design process, and to make use of all available information and potential sources of innovation. This poses the question of adapting their software to the company's organizational context, as well as the question of the compatibility of information systems within the company. Implementing an integrated information system -or more simply, a shared information system -should never hinder the development of a company [START_REF] Kadiri | Current situation of PLM systems in SME/SMI: survey's results and analysis[END_REF].

Therefore, the functionalities described in this section must be integrated when choosing and deploying a PLM tool in the specific field of the textile industry. In the section below, we analyze the constraints involved when applying these functionalities to the case of designing a textile product.

Adapting PLM to textile design

PLM tools are mainly derived from CAD software editors [START_REF] Maranzana | Collaborative design tools: a comparison between free software and PLM solutions in engineering education[END_REF]. Therefore the development of PLM in the textile industry closely follows the development of CAD in this sector. However, the use of CAD systems in clothing design is still quite restricted. There are two main reasons for this. First, CAD tools are difficult to access, in financial terms, for businesses whose main investments lie in raw materials. Second, design relies entirely on the use of patterns, which are two-dimensional. These patterns are then assembled to form an item of clothing (see Fig. 2). Since items of clothing are flexible, the types of constraints used in design depend on the pattern makers' experience, and is determined on a case-bycase basis. The well-recognized flowchart of CAD systems for 2D clothing includes the stages of fashion style design, pattern design, pattern grading and marker making [START_REF] Liu | A survey on CAD methods in 3D garment design[END_REF]. For example, typical commercial CAD software for 2D clothing include Gerber in United States, Shima Seiki in Japan or Lectra and Vetigraph in France.

A further contribution of CAD in textile design is the ability to carry out mechanical simulations in order to verify that the product's specifications are obeyed. These digital simulations have made it possible to drastically reduce development times in industrial product design. They rely on modelling systems, e.g. Finite Element Modelling. In the textile industry, modelling is a far more delicate matter. Consequently, its use is not quite so widespread. Indeed, designing and simulating virtual items of clothing involves combining a wide range of techniques, involving mechanical simulation, collision detection, and user interface techniques, all of which are adapted to the creation of items of clothing [START_REF] Volino | From early virtual garment simulation to interactive fashion design[END_REF]. Simulation tools are complex and take advantage of algorithms from the field of mechanical simulation, animation and rendering.

Then, in the field of the textile industry, concepts of configuration and traceability are essential. Indeed, each collection numbers roughly 1200 references, and each item of clothing corresponds to a pattern, which is given a specific colour and size, as it is destined for a target customer. Thus, configuring an item of clothing at Devanlay takes into account the following characteristics:

The item reference The colour, size, and design trends The product line: knitwear, weft, pullovers, and accessories The target market and production platform The patterning The related bill of material, which takes into account the regulatory constraints of the target market Cost and selling prices, which depend on the distribution channel In the next section, we draw a comparison between the main existing PLM solutions in order to determine their functional capabilities, in a textile application.

A functional comparison between PLM tools in the textile industry

In order to choose a suitable PLM solution, it is crucial to carry out a technical study of the functionalities present in various available commercial solutions. We have tested, in an industrial context, the ability of various commercial solutions to respond to designer requirements.

These solutions were tested in the field. Our evaluation was based on our use of the various pieces of software tested, running on a dedicated machine, and on our attendance of various technical presentations of these pieces of software. The tests took place over a period of three months, at the head office of a company in Paris. Following the presentation of ''industrial'' PLM tools by [START_REF] Maranzana | Collaborative design tools: a comparison between free software and PLM solutions in engineering education[END_REF], it can be noted that every piece of PLM software cannot easily be adapted for use in the textile industry. Indeed, whereas some software editors focus heavily on PDM, collaborative, and process management functionalities (e.g. Dassault Systems and PTC), other editors focus on collaboration and PDM functionalities primarily (Lawson) or, alternately, on textile-specific CAD functionalities (Lectra). Fig. 3 compares various solutions following different criteria.

Following this review, it can be noted that there currently exists no turnkey software solution which would provide all the functionalities expected of a PLM system suited to the textile industry. Consequently, the chosen tools must provide an adequate answer to the analysis of user needs, in the context of multi-user collaborations. Such user needs analysis may rely on interviews with representatives of the software's end-users [START_REF] Maguire | Methods to support human-centered design[END_REF][START_REF] Holzinger | Usability engineering for software developers[END_REF]. In the section below, we present the field work we carried out in order to formalize end-user requirements.

Research questions and methodology

As this state of the art suggests, PLM is one of the major evolutions in the practice of innovation design in recent years and has led to the development and diffusion of numerous software solutions. However, it also suggests that the textile industry Fig. 2. A 2D-to-3D transformation and simulation model used in the textile industry, adapted from [START_REF] Liu | A survey on CAD methods in 3D garment design[END_REF] and [START_REF] Volino | From early virtual garment simulation to interactive fashion design[END_REF].

presents a number of unique characteristics and requirements from the point of view of the design of tools to assist PLM, leading to the following questions: do the available tools truly address the needs of professionals in the textile industry, particularly in collaborative design teams? And what are the functions that are required in a collaborative tool for textile design?

To answer these questions, we have carried out a case study based on the principles outlined by Dul and Hak [START_REF] Dul | Case Study Methodology in Business Research[END_REF]. We will first present the context of our intervention, corresponding to what these authors call the stages of problem finding and problem diagnosis (Section 3.3); we will then describe an intervention consisting in the implementation of a new PLM environment at Devanlay, corresponding to the stages of design of intervention, implementation, and evaluation (Section 3.4). To answer the first research question noted above -focusing on user requirements analysis -we carried out a series of user interviews focusing on the kind of media used to support communication in collaborative work. To answer the second research question, the interview results served as a basis to define the functional specifications of a new tool, termed CoTeEn. Following a classical user-centred design methodology [START_REF] Nielsen | Usability Engineering[END_REF] we developed a mock-up of this collaborative tool which was subjected to user evaluation. In the stages of the project reported in this paper, we relied on questionnaires to assess the perception of various elements of the user interface by professionals in the company. Hence, our methodological proposal corresponds to the early stages of a user-centred design process, as defined by the ISO 9241-210 standard [START_REF]Ergonomics of Human-System Interaction[END_REF].

A case study in the textile industry

Context of the study and structure of the corporate group

The Devanlay group holds an exclusive license with the Lacoste clothing brand. Our industrial study took place mainly on the Paris site, where is located, in particular, the group's creation and marketing division. This office collaborates closely with a central development platform located in Troyes, France, which is in charge of product development. In the textile industry, the development cycle includes every stage from product launch up to withdrawal of the product from the market, but it is the stages of product definition and development which are the most demanding stages in terms of time and financial resources. Furthermore, the development cycle is unchanging, and corresponds to one season (there are two seasons per year). For example, Fig. 4 illustrates variations in stock size throughout the various stages of the product development cycle, in the case of the polo shirt -Lacoste's best-selling item. Many of the stages in this process can also be found in a classical product design process (needs analysis, conceptual design, implementation, etc.) as defined in [START_REF] Howard | Describing the creative design process by the integration of engineering design and cognitive psychology literature[END_REF][START_REF] Pahl | Engineering Design -A Systematic Approach[END_REF]. Other stages are more specific, such as structuring the collection, or restocking. Restocking involves reorganizing the stock of needed items, but can also refer to reordering items from suppliers in the event of unexpectedly high sales. Production volumes are approximately 250,000 items per reference. One element that is specific to the design of a collection of clothing, for the purpose of selling these items to wholesale dealers or salespersons, is organizing a convention in order to present the items of the collection, to start the ordering phase, and to launch large-scale manufacturing of the items.

Stakes of PLM in product design

Designing items of clothing is a cyclical task, in the sense that starting up a collection begins with the analysis of the last collection. At the Devanlay company, the product development cycle currently lasts between 20 and 22 months depending on the collection, before the collection is discontinued. The product's time to market is approximately 13 months to store delivery. For the sake of comparison, the table below, adapted from [START_REF] Segonds | Contribution to the Integration of a Collaborative Design Environment in the Early Stages of Design[END_REF], lists the time to market for the main textile brands. Over the past 25 years, the Lacoste collection has grown from 17 product references in 6 colours in 1985, to 1200 references in 8 colours in 2012. It stands to reason that the amount of technical data related to these items have grown accordingly (Table 1).

One of the priorities in implementing a PLM system in Devanlay is to foster creation and innovation in teams by reducing the administrative workload of operational teams. This aims to make it easier to implement a project and to improve the effectiveness of decision-making processes. This, in turn, will lead to reduced time to market and short manufacturing runs, making it possible to respond more efficiently to market needs. In this context, product development implies five main stages represented in Fig. 5:

Analysing and structuring the collection: the goal of this stage is to define which items of clothing will be commercialized in the future collection, and in what quantities. This relies on analysing past sales, market needs, and emerging trends. Defining the product: the goal here is to define each product in the collection (one collection amounts to between 250 and 300 references) in terms of its colour/theme/material/cut characteristics. One source of intermediary data at this stage is the concept sketch file, which specifies all the information related to the product (detailed description, sizing, materials, supplies, etc.). Product design: the goal here is to design and to validate prototypes of items of clothing (a few dozen pieces for each reference) depending on the previously defined criteria of colour/ theme/materials/cut. Product development aims to validate the definitive collection and to draft its final documents. Product industrialization: the goal is to produce the technical manufacturing file in order to launch manufacturing orders.

In order to support collaborative work and exchanges of technical data, the section below presents an experiment whose goal is to define the collaborative tools used by the company during product design. This allows us to provide adequate specifications for a PLM tool to support the textile design process.

Formulating the functional specifications of a collaborative PLM environment

User-Centred Design (UCD) of a collaborative PLM environment requires that decisions regarding system specifications be rooted in knowledge of end users' needs and activities. To produce such knowledge, we applied two different methods. We conducted a series of exploratory, open interviews with representatives of these end users, working in various departments of the company in order to better understand its workings (Section 3.3.1) and a questionnaire-based survey to learn about the tools used for collaboration in the company (Section 3.3.2). Analysing the media which workers used to communicate in their work allowed us to draw a list of functions required in the future PLM system (Section 3.3.3).

Exploratory interviews to understand collaborative work

Considering the complexity of the collaborative processes involved in the development of a textile product, as well as the sheer number of actors involved (about 300 people), characterizing the exchanges between these people is a crucial starting point in order to understand the collaborative activities which take place within the company. In order to provide the best possible specifications for a collaborative work environment, the first stage of our work aims to identify the main modes of communication used in the company.

In order to do this, we carried out a series of 18 interviews with a panel composed of professionals in clothing design at Devanlay,

Table 1

Examples of times to market in the textile industry [START_REF] Segonds | Contribution to the Integration of a Collaborative Design Environment in the Early Stages of Design[END_REF].

Brand

Time to market Devanlay (Lacoste) 13 months Celio, AT, Be ´re ´nice 6 months Zara 15 days Fig. 5. Stages of a textile product design process, from [START_REF] Gaillard | Expertise in the Clothing and Retail Sectors: the Devanlay and Lacoste Case Study[END_REF].

including six persons from the ''style'' department, six from the ''product design'' department, and six from the ''information systems'' (IS) department. The latter do not take part directly in the development of a collection, but they play a crucial role in the implementation of new software tools that reflect the work practices of support teams.

Interviews were transcribed verbatim and subjected to content analysis [START_REF] Krippendorff | Content Analysis. An Introduction to Its Methodology[END_REF]. This analysis focused on the functions of each department in the company, in order to understand the various tasks that might be carried out using the future PLM system. The roles of these departments are outlined in Table 2 below. The IS department is located at the crossroads between the company designers, based in Paris, and the engineers from product development, based in Troyes. Therefore, the persons from the IS department are in tune with what improvements could be made to their existing tools for collaboration. The three departments work in close collaboration throughout the early stages of the design process. One of the main goals of our interviews was to identify the forms of communication that were predominantly used within the company. Indeed, the fact that the company is located on two geographically separate sites makes exchanges between sites a crucial element of project success and completion. Analysing these communications, therefore, is a key part of the development of any new tool to support collaboration.

User surveys

Following the interview, the 18 participants took part in a questionnaire-based survey. This survey comprised two sections: (a) position occupied in the company and stages of the product lifecycle that their work focuses on; (b) media of communication used in everyday work. In addition, after filling in the survey, participants had the opportunity to discuss their responses with the experimenter is they wished to do so. We also used closed questions with Likert-type scales [START_REF] Likert | A technique for the measurement of attitudes[END_REF] to simplify data collection and analysis. This allowed us to collect precise data in a reasonable length of time (each survey lasted about 30 min) and fostered a genuine dialogue between the interviewer and interviewee, while preserving a framework that is tailored to the goals of the project. In our case, the questions focused on the types of communication tools used by the interviewees. Questions were grouped into four main topics: means of communication used, department involved in the communication, duration of use of the communication tool, and type of information transmitted.

Fig. 6 summarizes part of the results obtained in the surveys. Means of communication are classified depending on time (synchronous vs asynchronous communication) and space (colocation vs remote locations) [START_REF] Johansen | Groupware Computer Support for Business Teams[END_REF].

Each circle represents one specific tool for communication. The diameter of the circle is proportional to the average number of occurrences of each item in the 18 surveys. For example, company employees use email in 50% of all communication situations, confirming the findings presented by Brown [START_REF] Brown | The Product Lifecycle Collaboration Benchmark Report -The Product Profitability X-Factor[END_REF]. E-mail is the means of communication favoured by the participants in the product development process. One can deduce that a PLM tool will likely have to provide this means of communication, unless it is also provided through a dedicated email client.

Images are also frequently used as a means of communication (15% of cases). Indeed, in the early stages of the development process for the textile collection, IRs [START_REF] Bouchard | Nature and role of intermediate representations (IR) in the design process: case studies in car design[END_REF] of the product are almost exclusively graphical in nature (e.g. sketches, photos, outlines, etc. In particular, collection sketches have been identified as a key IR in the design process at Devanlay [START_REF] Segonds | Contribution to the Integration of a Collaborative Design Environment in the Early Stages of Design[END_REF]. Communication then relies on annotations made directly on the sketches. Another example is the ''wall of sketches'', which groups by topic every element of the collection on a magnetized wall. This makes it possible to have an overall view of the harmony present in the collection.

Next, telephone calls have an important part in current communication practices at Devanlay (10% of situations). Telephone is often used as a complement to email in the case of highly technical discussions on the details of product design.

Finally, paper-based communication documents, sketch walls, and interactions with these graphical representations cannot currently be implemented in the digital design process. One final type of collaborative tool is the tools used for managing and communicating data related to the products themselves, also called Product Data Management (PDM) systems. These are used in 5% of communications over the course of the product's lifecycle. Some of the key functionalities of these PDM tools should therefore be introduced in our proposal for a collaborative environment to assist the early stages of the textile design process.

All these observations are important to help develop a prototype. We are interested in knowing not just which tools are used, but also what type of information is exchanged. Indeed, based on these results, it seems that the product's IRs hold a number of key information that should be provided by our prototype. In the section below, we list all the technical data which should be managed throughout the lifecycle process of an item of clothing, as evidenced by our experimentation at Devanlay.

Listing the technical data required

The interviews as well as the responses to the user survey allowed us to draw up a list of the data required by the end users of the PLM system as part of their everyday work. The first element of the design process that produces data on the product is the creative idea, which yields a number of overall characteristics for the product including the silhouette, the fashion flat, and the fashion sketch. This dataset constitutes the product concept file. Then, the product file includes pattern drafts, grading specifications and bill of material. This marks the end of the stages of product design.

Later stages focus on the physical design of the product, starting with the prototyping stage that sets the data for the initial operating sequence. The last stage focuses on the production line, where the collection itself is generated through a process of dress rehearsal.

Fig. 7 illustrates the successive stages in referencing technical data and physical deliverables.

In addition to listing which collaborative tools were favoured in the company, our analysis thus allowed us to classify the types of IRs used. These specifications will be useful to the design and test of a collaborative platform.

Deployment and testing of a collaborative platform suited to the requirements of Devanlay: CoTeEn

We created the mock-up of a collaborative tool using Publisher in order to validate its main functionalities. The functional architecture of this tool, named CoTeEn for ''Collaborative Textile Environment'', is presented in Fig. 8.

Within this tool's functionalities, are included the main communication tools defined in Fig. 6. In particular, the CoTeEn tool allows direct access to e-mail (50% of the instances of collaboration) and also allows access to the various IRs of the product by using the ''search for reference'' thumbnail (15% of cases of collaboration).

Finally, we have developed an entire module dedicated to sketch-based collaboration via annotations, since this was identified as a key IRs in the design process at Devanlay [START_REF] Segonds | Contribution to the Integration of a Collaborative Design Environment in the Early Stages of Design[END_REF]. This module makes it possible for many people to collaborate and annotate product sketches in a synchronous or asynchronous manner. This tool makes it possible to centralize all the remarks related to a particular model, whether these remarks come from the style department, production department, or others.

The CoTeEn tool prototype, which serves to support a collaborative environment in the early stages of design in the textile industry, is represented in Fig. 9. It was subjected to numerous tests involving five experts in the company. Following these tests, the reactions of the experts were collected using a twopage questionnaire. This questionnaire is structured according to five key topics related to the functionalities that are expected from this tool:

The startup screen: are the icons clear? Does the tool make the users want to use it? etc. The design of the Human-Computer Interface (HCI): is the environment clearly presented? Is it consistent with the company identity? Are the contents well articulated with one another? Is the navigation intuitive? etc. Contents: does the tool offer new, interesting functionalities? Are there any functions lacking? Are the available options representative of my everyday work? Can the contents be understood without any additional explanation? Are the contents logically related? Etc. Communication: do the pages encourage you to interact with them? Overall: do you believe that this kind of collaborative environment for the early stages of design is realistic?

Users were requested to respond using a five-point Likert scale, ranging from ''not at all'' or ''totally ill-suited'' to ''absolutely'' or ''excellent''. Likert scales are more intuitive than Osgood's semantic differential scale [START_REF] Osgood | The Measurement of Meaning[END_REF]. A semantic analysis scale is in the form of a list of adjectives, or items, that are grouped in pairs and lined up, or separated by an odd number of boxes (usually 5 or 7). Allowing participants to position their judgement on each line as a point located between these two extremities. The central point corresponds to a neutral judgement. Although the meaning of the adjective is more precise in a semantic differential scale, the participant may feel uneasy during the evaluation. The reason why the adjectives are more precise is the presence of an antonym, which allows disambiguating the meaning of the adjective used. For example, the adjective ''intuitive'' has a different meaning depending on if it is associated with the adjective ''rational'' or with the expression ''requires learning''. However, the rating scale itself may be more difficult to fill in because of the fact that the rating is less intuitive.

For this reason, we have chosen to use Likert-scale [START_REF] Likert | A technique for the measurement of attitudes[END_REF] type ratings. However, one must point out that the expression Likert scale is ill-suited, since such scales do not use antonymous adjectives to specify their meaning. When choosing the items, the respondents to the questionnaire must be clearly identified. This makes it possible to adjust the tone and formulation of the questions and to use an appropriate vocabulary -one should not use technical terms when addressing newcomers.

Results concerning contents and communication are illustrated in Fig. 10. They show that the users subscribe completely to our proposal. The questions posed in this section of the questionnaire were: the site offers interesting new options that concern my work; there are options and functions missing; the options offered by the work environment are represented in my real work; contents are understandable without any further explanations; the contents are logically linked; contents motivated me to act (complete files, add documents etc.).

The most important criterion to us is obviously the contents proposed for the platform. These require, in order to be relevant, from designers to apprehend the complete design process. It emerges that the participants we have involved in the process appreciate this solution proposal, suggesting that the functional mock-up of our collaborative environment does indeed respond to the needs of users at Devanlay. Our work of formalizing this process has a lot to do with this result. Indeed, it allowed us to better understand the stakes of design and the contents that were necessary for the development of a product.

To answer our research questions, we demonstrated thanks to the series of user interviews that the available PLM tools don't truly address the needs of professionals in the textile industry. Then, using the basis of the interview and our state of the art, we have shown that the required functions in a collaborative tool for textile design are: messenger calendar and email functionalities, virtual meeting, workflow management, access to the various IRs and sketch-based annotation tool.

We will now propose a conclusion regarding the generalizability of these results and the process used in this case study.

Conclusions and prospects for future work

In this paper, we highlighted the key stakes in the implementation of a new PLM tool. Following a comprehensive review of existing PLM solutions and of the suitability of their functions to the world of textile design, we presented a case study of a company where we contributed to the design of a new PLM system to support design activities. To do this, we mapped and quantified the collaborative exchanges involved in the design of a textile product in the Devanlay company, based on a series of open interviews and on a survey carried out with end users working within the company. This allowed us to identify the product data that was required by these end users to carry out their design work, as part of a contribution to the early stages of the design process for this collaborative PLM system. The emergence of PLM tools, following increasing competition between businesses requires a fine-grained analysis of user needs, in terms of collaboration and exchanges of technical data before designing and deploying the system. The field work reported here allowed us to specify some useful solutions to implement a PLM solution. The method used for collecting and analyzing user needs, which are specific to the textile industry, can be replicated -and is necessary for defining a collaborative work environment that is optimally suited to user needs. Our approach, which is suited to the context of our intervention, makes it possible to deploy and test a tailored PLM solution, based on feedback from end users.

Fig. 1 .

 1 Fig. 1. Evolutions in design teams adapted from [3].

Fig. 3 .

 3 Fig. 3. Functionalities of various PLM systems.

Fig. 4 .

 4 Fig. 4. Evolutions in stock for one item over the course of one season, example for a white polo shirt.

Fig. 6 .

 6 Fig. 6. Representation of the main collaboration tools used in Devanlay.

Fig. 7 .

 7 Fig. 7. The process of product data creation.

Fig. 8 .

 8 Fig. 8. Structure of the pages in the functional mock-up of CoTeEn.

Fig. 9 .

 9 Fig. 9. CoTeEn's sketch-based annotation tool.

Table 2

 2 Departments involved in designing a new item of clothing, adapted from[START_REF] Segonds | Contribution to the Integration of a Collaborative Design Environment in the Early Stages of Design[END_REF].

	Department	Roles in the clothing design process
	Style	Analysing trends
		Defining new patterns
		Creating new patterns
		Defining variants in pattern colours depending on the
		structure of the collection
	Product design	Collecting market data
		Analysing sales from past seasons
		Structuring the collection in a collaboration with the
		style department
		Collaborate with the style department to create new
		patterns
		Produce documents for the collection
	Information Systems Selecting software programs suited to user needs
		Selecting database tools
		Implementing data storage space with tree structures
		intended to reflect the structure of the collection
		Ensuring quality and reliability of the transmitted
		information


Rezia Molfino
email: molfino@dimec.unige.it

Matteo Zoppi
email: zoppi@dimec.unige.it

Giovanni Gerardo Muscolo
email: muscolo@dimec.unige.it

Elvezia M Cepolina
email: elvezia.cepolina@dic.unipi.it

Alessandro Farina
email: alessandro.farina83@gmail.com

Fawzi Nashashibi
email: fawzi.nashashibi@inria.fr

Evangeline Pollard
email: evangeline.pollard@inria.fr

Jose Antonio Dominguez

Antonio Dominguez
email: joseantonio.dominguez@mazel-ingenieros.com

Giovanni Gerardo

Gerardo Muscolo', '

Elvezia M Cepolina'

' Fawzi

An Electro-Mobility System for Freight Service in Urban Areas

Keywords: full electric vehicle, sustainable freight service, service trips planning in urban areas intelligent mobility control neuroscience, locomotion, biomechanics, bio-robotics applied to sport, energy harvesting, dynamic balance systems

des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Author: Please supply zip code in all author's affiliation.

Elvezia M. Cepolina, PhD, Assistant Professor at the University of Pisa. She is Professor of Transport Planning at the University of Pisa and of Transport Design at the University of Genoa. She has been research fellow at the University College London, UK. She is the person in charge of scientific and technical/technological aspects in the following European projects for the University of Pisa: FURBOT, Freight Urban RoBOTic vehicle (FP7-SST-2011-RTD-1), PICAV, and Personal Intelligent City Accessible Vehicle System (FP7-SST-2008-RTD-1). She has been Overseas Scientist in the project SPIRAL Scientific Pedestrian Interaction Research in an Accessibility Laboratory, International Joint Project -2004/R3-EU Europe (ESEP), founded by Royal Society, UK. She is author of many papers on international journals and international conference proceedings. She is a member of the SIDT (Italian Society of Transport Professors).

Alessandro Farina received the MS in Civil Engineering from the University of Bologna, Italy, in 2009, and the PhD from the University of Pisa, in 2012. He is currently a research associate at the University of Pisa. His research interests include car sharing systems, transport logistics, and maritime transport.

Fawzi Nashashibi is the Program Manager of IMARA Team at INRIA (Paris-Rocquencourt). He has been senior researcher and Program Manager in the Robotics Centre, Mines ParisTech since 1994. He was previously a research engineer at PROMIP (working on mobile robotics perception dedicated to space exploration) and a technical manager at Light Co. where he led the developments of Virtual/Augmented Reality applications. He has an MS in Automation, Industrial Engineering and Signal Processing (LAAS/CNRS), a PhD in Robotics from Toulouse University prepared in (LAAS/CNRS) laboratory, and a HDR Diploma (Accreditation to research supervision) from University of Jussieu (Paris 6). His main research topics are in environment perception and multi-sensor fusion, vehicle positioning, and environment 3D modelling with main applications in Intelligent Transport Systems and Robotics. He played key roles in more than 50 European and national French projects on ITS and robotics, some of which he is coordinator. He is author of numerous publications and patents in the field of ITS and ADAS systems. Since 1994 he is also a lecturer in several French universities. He is a member of the International TRB Committee on Vehicle Highway Automation (AHB3). He is member of the IEEE ITS Society and the Robotics & Automation Society. He is an Associate Editor of several IEEE international conferences such as ICRA, IROS, IV, and ICAR.

Evangeline Pollard obtained her signal and image processing MS in 2007 from the University of Lyons. That same year she graduated from the 'CPE-Lyons' Engineering School in electronics, telecommunications, and computing. In 2010 she obtained her PhD at the French Aerospace Lab (Onera). During 2005-2006 she worked at the German Aerospace laboratories (DLR) in Munich on the TerraSAR-X processor. After a postdoc with the Livic and the Université de Sherbrooke, Canada, for driving assistance applications, she is pursuing her work on data fusion and multi-target tracking on driving applications at Inria-Imara, Paris, France. J.A. Dominguez started working at Mazel in 2004. He has been working developing electronic control units basically for the automotive industry, from car racing teams to standard car manufacturers. His basic competences have been in-car communication and car lighting systems. He has also specialised in wiring harness development and industrialisation for the automotive and railroad industry. Since 2010 he has been working in electromobility projects.

Introduction

The freight transport has an important role in urban transport issues. Goods movement represents between 20 and 30% of vehicle kilometres corresponding to 16-50% of the emissions of air pollutants, depending on the pollutant considered, by transport activities in a city [START_REF] De | Recent developments in national and international freight transport models within Europe[END_REF]. Furthermore, vehicles serving urban delivery operations are a well-established contributing factor to urban traffic congestion and increasing atmospheric pollution [START_REF] Yannis | Effects of urban delivery restrictions on traffic movements[END_REF].

Author: If a previous version of your paper has originally been presented at a conference please complete the statement to this effect or delete if not applicable.

The large majority of countries have not yet found adequate solutions to help optimise the urban movement of goods. It actually seems that all players are expecting initiatives to come from the other side. On the one hand, city governments expect businesses to set up new logistics services fit to the emerging needs of the customers and retailers; on the other, logistics providers wait for municipalities to initiate (and subsidise) new services before starting a business, which could prove poorly profitable and highly risky [START_REF] Dablanc | Goods transport in large European cities: Difficult to organize, difficult to modernize[END_REF]. A combination of commercial initiatives and government policies could be necessary in developing a sustainable urban freight system [START_REF] Anderson | Urban logistics, How can it meet policy makers' sustainability objectives?[END_REF]. Most of the resources at the city level are focused on public transport and cars, as shown by [START_REF] Zunder | Urban freight logistics in the European union[END_REF] within the European project BESTUFS.

A sustainable freights transport has to fulfil the following objectives [START_REF] Behrends | The impact of Urban freight transport: a definition of sustainability from an actor's perspective[END_REF]:

• reduce air pollution, greenhouse gas emissions, noise to levels without negative impacts on the health of the citizens or nature • ensure the accessibility offered by the transport system to all categories of freight transport • improve the resource and energy efficiency and cost-effectiveness of the transportation of goods, taking into account the external costs • contribute to the enhancement of the attractiveness and quality of the urban environment, by avoiding accidents, minimising the use of land, and without compromising the mobility of citizens.

The retail sector demonstrates how fragmentation of demand for urban freight transport (e.g., numerous independent retail outlets located in a city centre) combined with the fragmentation of supply of urban freight transport (e.g., numerous wholesalers and other suppliers using their own vehicles to make just-in-time deliveries) results in a greater number of urban freight transport movements with only part-loads than would be possible if both demand and supply were more concentrated. The larger retail chains have greater volumes of traffic and are more likely, by working with their logistics providers, to be able to optimise their deliveries in terms of overall efficiency. While diversity in the retail sector provided by small and medium-sized independent retail outlets offers greater choice for consumers and can be seen as providing wider benefits to society, economies of scale in the provision of freight transport services in all sectors tend to lead to greater logistics efficiency, lower costs, and more sustainable distribution.

Inefficiency in distribution in urban areas can be exhibited in the following ways: • low load factors and empty running

• a high number of deliveries made to individual premises within a given time period

• long dwell times at loading and unloading points

• bad use of infrastructures (e.g., delivery areas, off-peak deliveries).

Inefficiency in distribution leads to additional costs for transport operators, which would normally be passed on to receivers/shippers (in the case of third party operators) or absorbed as costs for own account operators. These costs are ultimately borne by the wider economy. However, shippers, receivers, and their transport operators do not always have a significant incentive to increase the efficiency of the deliveries to reduce costs. This is because the transport cost is often only a small proportion of the value of the goods that are being transported and the overall costs of the shippers/receivers (MDS Transmodal Limited, 2012).

These problems related to urban freight distribution are going to increase in the future because urbanisation will bring more consumers in urban areas and more freight will be addressed to consumers since e-commerce is quickly increasing. Just some data: in Europe the total e-commerce revenue in 2012 was 305 billion of euro and 43% of the European population buys habitually online products and services (source: Eurostat) (Eurostat website, 2013). In 2012, in Italy e-commerce moved 76,000 packages each day and, comparing with 2011, the growth rate was remarkable (15%). This growth trend is expected to continue (Osservatori.net, 2013).

New solutions for urban freight distribution have been recently proposed in order to limit the number of trucks in downtown during rush hour thereby decongesting the cities, providing flexibility for recipients who recover their packages when they want to, to contribute to a better logistics organisation of malls, and decongest delivery areas. Among these new solutions, Pack stations and Bento boxes are very interesting since they reduce the capillarity of last mile freight distribution, concentrating packages in fixed point and asking the receivers to collect them.

Pack station is a service run by DHL Germany and provides automated booths for self-service collection of parcels and oversized letters as well as self-service dispatch of parcels 24 hours a day, seven days a week. The structure is fixed. The pack station can be used for both the delivery of packages to customers and by customers to send their packages. The advantage of pack station is the concentration of packages directed to customers into a few localisations; therefore no empty trips occur, as receivers have a time window to collect their packages, and the number of delivery trips is reduced thanks to the reduction of the capillarity of demand. However, pack stations register two main disadvantages:

• they have a fixed location in the urban areas and their number is fixed a priori

• the loading operations take place only at the pack stations locations.

Regarding the first disadvantage, the demand for packages varies every day in quantity and the distance between pack stations and customers may be quite high in some cases; moreover, in some cases, the available pack stations may not be sufficient to satisfy the demand or one or more pack stations may be empty. Regarding the second disadvantage, operative costs are high; moreover the road space besides the pack station may be occupied for a long time and therefore this creates some impedance to vehicular flows.

The BentoBox, designed within the project CityLog, with the participation of TNT Express, has been developed with the aim of resolving the second disadvantage of pack stations. It is composed of a fixed docking station and six removable modular trolleys. Trolleys are consolidated at the Urban Distribution Centre (UDC). A new small container has been proposed within the project CityLog to accommodate the trolleys: BentoBox trolleys are loaded into the small container in the UDC and unloaded at the docking station. Therefore the unloading time at the docking station is reduced to a minimum and operative costs are minimised. However, as for Pack stations, the number and the localisations of the BentoBox docking stations are fixed for a given urban area and do not depend on the current freight demand.

In this paper, new concept architectures of light duty fully electrical vehicles for efficient sustainable urban freight transport are proposed and analysed. The main paradigms of the new vehicle architecture design are energy efficiency, living city environment and eco sustainability, mobility dexterity, modularity, intelligent automated driving, and freight handling robotisation.

The architecture of the vehicle, named FURBOT, is conceived modularly: the main modules are the cab and the chassis/mobile platform. The payload is considered packaged in freights boxes or ISO pallets. The mobile platform integrates electrical modules for power generation, vehicle propulsion, and driving, together with the relative software control modules, which are explained in [START_REF] Muscolo | A novel robotic handling device integrated on a freight Urban robotic vehicle[END_REF], [START_REF] Dinale | A new robotized vehicle for urban freight transport[END_REF] and [START_REF] Molfino | A robotic vehicle for freight delivery in Urban areas[END_REF].

Freight boxes, dedicated to different kind of freights, are purposely designed together with the architecture of the FURBOT vehicle: the boxes have the same ISO pallet standard footprint size and bottom shape to be easily handled by the on-board robotised system.

In order to realise a suitable and feasible handling device for the pallets or boxes loading/unloading, the handling device was conceived both harmonised with the vehicle's chassis structure to achieve an easy integration of the overall system and, at the same time, as a separate sub-system of the vehicle, becoming hence an optional service device.

The paper is structured as follows: Section II shows the conceptual and functional design of the FURBOT vehicle, its robotic handling device, and its power supply. Section III shows the intelligent mobility control system of the vehicle. Section IV describes the service trips planning in urban areas. Finally, the possible results of the integration of these technologies and the future works are discussed.

FURBOT vehicle design

Requirements and vehicle layout

The architecture and design of the vehicle have addressed the following requirements:

• The loading/unloading process is realised from the right side of the vehicle since about 70% of the world's total road distance carries traffic on the right.

• The loading volume capacity is of two Euro-pallets (800 mm × 1200 mm) or two dedicated boxes with same base size; maximum height 1800 mm.

• The maximum total payload carried is one metric ton. The mass is distributed between the two pallets (or boxes), average 500 kg for each; an unbalance of 100 kg between the pallets is admitted (400 kg one pallet, 600 kg the other one).

• The loading of the pallets or boxes is done from the 800 mm side.

The load can be picked up directly from the ground level or from a step (typically the pavement) with a maximum height of 150 mm at a maximum distance of 500 mm from the vehicle's side.

The layout selected for the vehicle is shown in Figure 1. It has been developed to maximise the payload volume to total volume ratio, and the payload mass to total vehicle mass ratio. The choice of the layout depends on the positions of the pallets and directions of loading/unloading, and on the volume and base area required by battery, driver, wheels, motors, and control/power electronics. Simulations of vehicle manoeuvring in narrow streets (typical of pedestrian old city centres) indicate that a rectangular shape is preferable to a square shape; furthermore, the loading from sides is preferable to the loading from front/back because the parcels do not obstruct the motion of the vehicle once deposited. In conclusion, the layout adopted is with pallets in the centre loaded from sides and driver and services in the front and back of the vehicle. The values achieved for the objective rations on mass and volume are higher than for all existing electrical carriers: volume ratio 0.48 and mass ratio 1.05. They are also higher than for the majority of combustion engine carriers (which are advantaged by the higher energy density of fuels compared to batteries).

The main components to accommodate in the front and back are the battery, two electric motors, a driver place, cockpit and command interfaces, control and power electronics. An optimal distribution, resulting from the study of several alternative and intermediate architectures, is with battery, motors, and electronics on the back, while the front is for driver and commands. The width is the same as the pallet with an extra space for the mechanisms of the loading devices. To minimise the length, the driver is sitting with commands distributed at the sides and the door to access the cabin is in the front.

For the loading, the vehicle approaches one pallet or box at a time, parking at a side of it facing an empty slot on the loading bay. Unloading is done at reverse, with the box deposited at a side of the vehicle. The boxes are placed over a beam frame in the bottom of the loading deck. The goods, once loaded, are laid on the deck, centred with respect to the vehicle centreline plane.

The vehicle structure

The frame is made of welded AISI304 square hollow pipes. The floor of the loading bay uses four 100 mm × 40 mm × 2 mm thickness pipes with transversal connection beams (see Figure 2). The four suspensions span 180 mm vertical translation and allow to move the loading deck from driving height (maximum height) to any intermediate loading/unloading height upto deck laying on the ground (minimum height). Each suspension comprises a hydraulic ram with gas spring and a shock absorber in series; this assembly pivots on a ball joint on the chassis and is hinged to the wheel assembly. This solution is original and transforms the vehicle in a platform with height from ground adjustable continuously.

The steering of the front wheels is operated by a servo electric motor driving a mechanical commercial steering bar [START_REF] Callegari | Concerning stability and dynamic analysis of a four steering wheels vehicle driven by 'in wheel' engines[END_REF]. The traction power is 15 kW at wheels (tyre size 165/75 R14). Full loaded, the vehicle negotiates slopes up to 10% and the max speed is 30 km/h. These speed and slope capacities result from a campaign of simulations of delivery in the cities of Lisbon and Genoa with typical delivery paths.

The structural design of the frame has been developed through two sets of analyses: static for the first definition of the geometry and sections; dynamic with time variant external loads at the interfaces of the suspensions to minimise the mass of the structure.

The robotised freight handling

The loading/unloading process is automated. The vehicle is approached to the parcel by the driver. The laser scanners for the monitoring of the drive are now used to identify the relative position between vehicle and parcel; the information is used for the automatic fine self-alignment vehicle-parcel required to ensure the insertion of the forks in the slots [START_REF] Muscolo | A novel robotic handling device integrated on a freight Urban robotic vehicle[END_REF].

Once the vehicle is fine-positioned, the following steps are applied: • check that the distance between box/pallet is less than 500 mm and all other position tolerances are satisfied • use the active suspensions to move the loading deck to proper height with respect to the pallet/box to load; the frame with forks translates with respect to the base and a short lift is available (120 mm), sufficient to move the bottom face of the pallet/box above the floor surface of the loading deck • move outward the forks in lower configuration, insert them in the bottom of the pallet/box, lift up the forks, retract the forks, translate down the forks to position the pallet/box on the loading deck • lift up the suspensions to driving height.

The unloading is done analogously in reverse order.

Frames explaining the motion of the forks during a loading cycle are shown in Figure 3. Figure 4 shows the sub-assemblies of the loading unit. Each handling unit comprises a fork translating horizontally along two telescopic rails and vertically. The fork is linked to a fork slider by four cranks forming, with the fork body, two 4-bar linkages; a vertical ram on the back actuates the translation. The fork slider translates with respect to the intermediate slider along a pair of parallel rails; actuation is provided by a ram positioned at the left side of the loading unit. The intermediate slider slides with respect to the base of the loading unit along another pair of rails parallel to the other rails; the actuation is by a ram positioned at the right side of the loading unit. The packaging of this assembly was especially complex due to the small section available for each fork to insert in the slot of the pallet (220 × 90 mm).

The power supply

The power supply unit is in charge of storing and providing the energy required for the operation of the vehicle. The complete system is composed of cells, the battery management system, the balancing system, the power distributor, three voltage power supplies, and the battery charger. The first step to design the power supply system was to calculate the amount of energy needed and the maximum power required. The power requirements come from the conditions of use. The main consumers are the power train, the forklift system, and the auxiliary service. The power train system is responsible for moving the vehicle and has to overcome three main forces: rolling, aerodynamic, and slope. According to calculations the force that has most influence in the power requirements is that related to the slope. As there was a restriction of 15 kW for the power train system, the power supply unit has to be able to provide this amount of power.

The condition where this limit is reached is when driving on a 6% slope at 29 km/h or when driving on a 23% slope at 10 km/h. The maximum power required for the forklift systems depends on load weight and the time of operation and is around 3 kW. Finally, some estimation using standard components in the automotive and robotics industry have led to consider it around 2 kW.

Once the maximum power is calculated, estimation about the amount of energy that has to be stored in the battery system is needed. This has to take into account the power requirements and the conditions of use. For this purpose a simple model of the vehicle was developed, taking into account only the slope and aerodynamic forces. With this model the behaviour of the vehicle in some scenarios with different terrain sections, speed, and hours of operation was simulated. With this information and the correction for the service system and forklift system, the total amount of energy has been approximated by 17 kWh.

Having the maximum power requirements and the total amount of energy needed, the next step was to decide the energy storage device. LiFePo 4 battery has the ability to deliver more current than its nominal current (C parameter). This permits to have a safety margin and be able to deliver more current to the consumers. Next step was to design the system responsible for managing the battery in order to make it work within the safety and operating limits of voltage, current, and temperature. This battery management system performs the cell balancing as well. Cell balancing is needed in order to increase battery life and to improve the overall battery system autonomy. The objective of this technique is to have all the cells with the same amount of charge and transferring charge among cells. The main features of the battery management system are SOC (state of charge) and SOH (state of health) determination, balancing management, and monitoring of critical parameters. The system transmits all this information through the CAN bus and is able to receive messages to perform some actions.

Figure 5 shows a sketch of the general architecture of the power supply.

The battery is charged with a dedicated battery charger, connected to 220 V AC and can deliver up to 5.5 A. The charger is connected to the CAN bus and receives information about the SOC of the battery and its balancing level and adjusts the amount of current with this information. Another necessary feature of the power supply is that it has to be able to power all the devices in the vehicle. The main voltage of the battery is limited by the power train motors, which work at 96 V DC. Apart from these motors, there are other elements such as pumps, lights, computers, sensors, etc. that need to be powered at their nominal voltages. After a study about the electrical and electronic devices needed to perform the vehicle operation, 5 V, 12 V, and 24 V were used. The power supplies can communicate with external devices through the CAN bus and are able to detect if a fuse has been broken, the power that they are delivering, the input and output voltage, etc.

Finally, the power distribution system is in charge of managing the overall system and to determine if the battery has to be disconnected. It also contains most of the safety features such as power fuses, relays, and contactors. Apart from the traction voltage, there are separate lines with the same voltage, one dedicated to control and the other dedicated to power. The purpose of these two lines is that, in safety conditions, it is necessary that the control system will be active in order to solve the problems or to recover the system from the critical conditions. A main power contactor disconnects the overall battery system in case of safety critical operation of the battery. The driving estimated range of FURBOT operation will be around 60 km, with a total amount of 12 kWh for traction, 3 kWh for forklift system, and 2 kWh for service.

Intelligent mobility control system

General architecture

In addition to designing a new vehicle with a new power management system and a new forklift and an innovative freight transportation system, our goal is to create intelligent mobility illustrated in Figure 6. For this purpose, the FURBOT vehicle is equipped with many sensors (Lidar, cameras, etc.) in order to observe its environment and to localise itself, with computers to process these data, actuators to command the vehicle and with human machine interface (HMI) to interact with the driver. As data coming from sensors are noisy, inaccurate, and can also be unreliable or unsynchronised, the use of data fusion techniques is required in order to provide the most accurate situation assessment as possible [START_REF] Hall | An introduction to multisensor data fusion[END_REF]. For this application, situation assessment consists of merging information about the vehicle state by itself (position, velocity, acceleration, battery level, etc.) to accurately localise the vehicle, detecting potential obstacles like other vehicles, bicycles, or pedestrians but more generally, detecting the free area where the vehicle can move also by using lane detection, and also in detecting and identifying freight boxes. To help the driver, global planning (itinerary calculation) is made using online maps. When required, local planning can be made to calculate the vehicle path and the corresponding commands for the lateral and longitudinal control are sent to the lower level. Mission orders are coming from the UDC through communication (see Section 4).

The Furbot vehicle is equipped with an embedded computer to process all these data. The general control architecture shown in Figure 6(a) has been implemented using the software RTMaps [START_REF] Steux | RTmaps: a framework for prototyping automotive multi-sensor applications[END_REF] which is a real-time prototyping system as illustrated in Figure 6(b). Each box represents an elementary process with given inputs/outputs/ properties.

Special attention has been given to the HMI. It is a web interface sharing information with real-time maps (RTMaps) through a MySql server. It will be deployed on a tablet computer, which has the advantage of being a transportable touch screen. It will play three key roles:

• provide general information to the driver on the situation assessment (itinerary, localisation, etc.)

• warn the driver in case of emergency

• allow the driver to choose the driving mode.

Three driving modes

In this application, the FURBOT vehicle can be driven in three different modes:

• fully manual • assisted • fully automated.
In the fully manual mode, the vehicle is driven through a joystick and the driving command is directly transmitted to the low level control. The joystick command can come from a physical joystick or from a virtual one, represented on the tablet. In this way, the driver can go down from the cabin to perform a tricky manoeuvre.

Also, in order to help the driver in the driving process, an assisted driving mode (eg. with advanced driver assistance systems or ADAS) is provided. The goal is to improve road safety and driver comfort. Special attention has been given to the obstacle detection and tracking for adaptive cruise control (ACC), as well as the collision risk assessment. In order to help the driver to accomplish his mission, a precise localisation is provided with a basic GPS device, proprioceptive data, and a map of the environment.

More information about algorithms are available in [START_REF] Resende | Low speed automation: technical feasibility of the driving sharing in urban areas[END_REF]). An itinerary is proposed as part of the global planning.

The third and most ambitious driving mode is the fully automated one which is more accurately described in the next section.

Automation of the loading/unloading stage

Several cases must be considered for the automation of box loading/unloading:

• Loading of a box in an UDC: In this scenario, a mission has been assigned to the driver and he is now looking for the right box to load in the UDC. He is going all over the UDC to find the box with the manual or assisted driving mode. He can then monitor the box research through the 'box' tab of the HMI. When the vehicle becomes close enough to the right box, the RFID receptor is activated by the RFID tag of the right box (from a distance of one metre) and the box is identified. The driver can visualise it in real time on the HMI through the side camera. At this moment, the automatic driving mode is available and can be chosen by the driver through the HMI. When the 'loading mode' is activated, a confirmation order message is sent and the FURBOT vehicle automatically moves until it gets well positioned regarding the box. • Loading of a box in bay areas: Bay areas are located inside the cities and are chosen as flat areas with large free space to let the FURBOT vehicle go. However, contrary to the UDC, the environment is not controlled and some obstacles can obstruct the path of the FURBOT, preventing it from positioning itself regarding the box. In this case, the vehicle has to manoeuvre (front and rear manoeuvres) and elaborate complex paths to pursue its goal (see Figure 7). Bang-bang control for the time-delay system which takes into account the steering dynamics and a stable second order linear is used as made in (Perez et al., 2013).

Unloading a box: For the unloading case, there is no distinction between UDC and bay areas. The driver is in charge of choosing the unloading location. The role of the system is twofold for this task. First, it has to inform the driver about the future location of the box using templates which will be projected onto the images of a video stream provided by the FURBOT external camera. It implies that the camera should point at the loading/unloading area. The second task consists in ensuring that there is enough space to unload the box. It allows the driver to choose the 'unloading mode' only if no obstacle is detected. If a moving obstacle is detected on the box path and if the collision risk increases, then the unloading process will automatically stop. Laser data are used for the obstacle detection. Laser impacts are segmented in order to detect objects and they are projected on the image to inform the driver. In Figure 8, the HMI provides some augmented reality to help the driver to choose the location of the unloading. Free space is delimited by orange colour. Bounding boxes surround the potential obstacles (here another vehicle). And the location of the box if unloaded is projected on the image. Green colour indicates that the location is free (red colour will mean the opposite), and the 'unload' button is available. 4 Service trips planning in urban areas

The proposed freight transport system

The proposed FURBOT transport system is meant to overcome the two disadvantages of pack stations described in the introduction. The number and the localisations of the FURBOT load units are not fixed a priori in the urban area and they depend on the current daily freight transport demand. The impact of the FURBOT load units on the land occupation is therefore minimum, as the load units are placed only where required. Moreover, the unloading of the FURBOT load unit is automatic.

The FURBOT system works as follows. At the beginning of the day the freight arrives at the UDC, on the border of the urban area, in pallets or in packages. Packages could be sacks, large and small boxes, envelopes and so on. Freight receivers are end consumers or retailers. Retailers and end consumers are potential FURBOT freight transport system users. While packages could be addressed to both end consumers and retailers, pallets usually are addressed only to retailers.

At the UDC, freight is split in load units. In the following, this problem is denoted as the sub-problem 1. The load units have a standard dimension: 800 mm × 1200 mm (footprint) × 1800 mm (H) maximum. There are two types of load units: the LBL box and the FBL box or pallet. A LBL box is divided in parcels (multi-parcels box) and each parcel can accommodate packages addressed to a given receiver. A FBL unit is a Euro ISO pallet or a box instead contains a Euro ISO pallet addressed to a given commercial activity place. An unloading bay is associated with each LBL box, according to the addresses of the packages contained in it. FBL boxes will be delivered at the commercial activities places. A virtual key and the actual address of the LBL box's unloading bay will be communicated to all the receivers. The receivers are then in charge of collecting their packages. A receiver has to travel from the address of his package (for instance, their home address) to the unloading bay where the LBL box containing it has been unloaded. This is an assumption of authors.

At the UDC, FURBOT vehicles are consolidated. In the following, this problem is denoted as sub-problem 2. According with the FURBOT vehicle design, each vehicle is able to carry 2 load units. Units are loaded on each vehicle, according to their unloading bays and/or commercial activity addresses. Consolidated vehicles start then the freight distribution in the urban area. According to the time at disposal for completing the freight distribution, each vehicle could perform more than one delivery trip. In a short dwell time, the units are automatically unloaded in the bays or close to commercial activity places [START_REF] Muscolo | A novel robotic handling device integrated on a freight Urban robotic vehicle[END_REF]. Text messages are sent to the receivers informing them that the freight has been delivered, indicating where it has been delivered, the PIN code to access it, and the time window available to collect the freight.

At the end of this time window, the FURBOT fleet starts to collect the load units and to carry them from the urban area to the UDC (reverse logistics). The load units could be empty or could contain freight that has not yet been collected by the receivers or packages addressed outside the urban area. In the second case, the packages will be joined to the freight that arrive at the UDC in the following day and split again in the load units.

If a freight unit is designed to only one commercial activity (FBL unit), the FURBOT system results convenient only if an unloading bay is present close to the receiver and the pallet or box is delivered by night. In this case the cost for purchasing the box is justified by the advantage of having less freight vehicles circulating during the day. If there is not any available unloading bay close to the commercial activity, the delivery can be performed only when a receiver is available for receiving the freight at the moment of delivery and no security system for the freight unit is necessary.

The system optimisation procedure

A methodology has been developed for solving the two sub-problems. The target is to minimise the daily system cost. The daily system cost S is the sum of the daily user cost and the daily operator cost.

The daily system cost S has two components: the user cost c user and the operator cost c operator :

user user operator operator S c c ϑ ϑ = ⋅ + ⋅ (1)
where user ϑ and operator ϑ are weighting coefficients, assumed equal to 1.

The daily user cost is a function of the overall distance travelled by receivers in a day to collect their packages at the unloading bays: • c pd = cost of an unit of walking distance, assumed to be equal for all the receivers.

It has been taken equal to that for public transport users, which, according to [START_REF] Shimamoto | Evaluation of an existing bus network using a transit network optimisation model: a case study of the Hiroshima City Bus network[END_REF], is 0.36 €/min.

• The daily operator cost is a function of the overall distance travelled by FURBOT vehicles in a day, of the fleet dimension, and of the number of LBL and FBL load units. The daily operator cost has the following expression: it is function of the vehicle power consumption and therefore of the vehicle routing • q km = the quantity of kilometres travelled by FURBOT vehicles each day.

The average fees of usage of LBL and FBL load units do not appear in this formula, as they are contemporarily user's costs and operator revenues, and therefore do not affect the daily system cost minimisation.

Every day the proposed methodology allows to assess the number of LBL boxes (n LBL *), the fleet dimension n v *, the box consolidation and the vehicle routing that minimise the system cost, given the actual freight transport demand, the road network, and the delivery time window (see Figure 9).

The freight transport demand is given in the form of a matrix, whose rows correspond to packages and pallet dimensions and columns to receiver addresses.

Regarding the road network, the authors consider the footway network, for receivers collecting their packages, and the FURBOT vehicles road network, for FURBOT vehicles performing the LBL and FBL units deliveries.

The delivery time window is assumed from 6 a.m. to 7:30 a.m, and from 9 a.m. to 12 a.m. It has been chosen not to perform deliveries in the morning peak period; therefore, delivery trips do not increase their duration because of road congestion, and impedance to passenger cars because of FURBOT vehicles is avoided. Moreover, during the peak hour FURBOT vehicles can be put in charge.

The proposed methodology, through a simulated annealing (SA) algorithm, explores the search space, given by the n LBL admissible values, in order to minimise the daily system cost. For the case of study of the historical city centre of Genoa, Italy, the search space ranges between 1115 and 3715 nLBL and, with a given freight demand of 22500 packages plus 200 pallets, the methodology provided 1195 LBL boxes and a required fleet of 108 vehicles as optimal results. The SA algorithm converges quickly to the optimal solution. The robustness of the algorithm has been tested with different cooling schedules, neighbour search, and stopping criteria. The computation time depends on the computational time required for the box consolidation process and for the vehicle routing.

Figure 9 The optimisation methodology

The system cost, for a given n LBL , is calculated by sequentially resolving two subproblems, as shown in Figure 9. The first sub-problem optimises the consolidation of freight in the FURBOT LBL boxes from which the user's cost depends. Given a number nLBL of LBL boxes, the goal is to find the sets of packages to load in each LBL box and to define the unloading bay for each box that minimises the overall distance travelled by the receivers of the packages in the box. The problem constraints are the capacity of the box and the maximum distance that can be accepted by users. A fuzzy k-means clustering algorithm has been adopted. Details of this algorithm are provided in [START_REF] Cepolina | An optimization methodology for the consolidation of urban freight boxes[END_REF]. For the case study of the historical city centre of Genoa, the optimisation of the box consolidation provides the following results: average load factor of the 1195 LBL boxes equal to 93%, the maximum walking distance equal to 362 metres, average walking distance equal to 24.72 metres. The robustness of the algorithm has been tested with different starting points (initial bay localisations) and stopping criteria. The computation time of the adopted methodology results very sensitive to the freight demand and slightly sensitive to the initial bay localisations.

The second sub-problem minimises the overall travel time related to the delivery trips from which the number of required FURBOT vehicles (n v ) depends. The travel time for each road section is assumed to be constant but it is related to the average pedestrian and vehicular flows on the road section. The FURBOT vehicle routing can be formalised as the capacitated vehicle routing problem (CVRP), with some modifications, and genetic algorithm is used to get the optimisation solution, according to [START_REF] Is 'perez | Applying genetic algorithm for capacitated vehicle routing problem[END_REF]. The output of the algorithm is the number of required FURBOT trips: for each FURBOT trip, the algorithm provides the identifications of the boxes that will be delivered in the trip, the travel time, the trip length, and the energy consumption. Freight deliveries take place in a given time window: therefore the required FURBOT fleet dimension could be assessed given the travel times of the required FURBOT trips and the delivery time window. Details of this algorithm are provided in [START_REF] Cepolina | The routing problem of an innovative urban freight distribution scheme[END_REF]. For the case study of the historical city centre of Genoa, the vehicle routing optimisation provides the following results: the required number of delivery trips is 698, the travelled kilometres are 4925.3, the maximum trip length is equal to 12 kilometres, and the average trip length is 7.0 kilometres. According to the simulation results, the power system provides enough autonomy for the longest trip, including the energy required for the forklift cycles. The robustness of the algorithm has been tested with different initial chromosomes. The routing algorithm converges quickly to the optimal solution even under a high freight demand and a wide network.

Conclusion

The design results addressed in the paper are in line with the Horizon 2020 objectives about measures and tools to achieve essentially zero emission city logistics in urban centres by 2030. These design results will be soon integrated in a new fully electric vehicle physical prototype endowed with an innovative and agile freight manipulation system, an efficient power supply and distribution, an intelligent multi-level online control system, and an offline policy framework, allowing sustainable urban logistics solutions through a FURBOT fleet. The achieved results have been validated through advanced virtual testing on 3D models as well as simulation of the perception motion control and the service trips planning strategies.

Figure 1

 1 Figure 1 Digital mock-up with highlight of the vehicle layout (top) and vehicle layouts studied (bottom): the layout finally selected is the one on the right (see online version for colours)

Figure 2

 2 Figure 2 Prototype at shop testing (cover removed to show the inside) (see online version for colours)

Figure 3 Figure 4

 34 Figure 3 FURBOT unloading cycle (from top to bottom, from left to right): intermediate positions of the fork loading an empty pallet (see online version for colours)

Figure 5

 5 Figure 5 Sketch of the general architecture of the power supply (see online version for colours)

Figure 6

 6 Figure 6 (a) General control architecture of the Furbot vehicle and (b) its implementation with the RTMaps software (see online version for colours)

Figure 7

 7 Figure 7 Illustration of the box loading in a bay area with an obstacle (see online version for colours)

Figure 8

 8 Figure 8 Augmented reality through the HMI (see online version for colours)

  i = walking distance covered by the ith receiver: it depends on the position of the unloading bay where the package has been delivered, therefore on the number of LBL boxes (n LBL ) and on the box consolidation process.• d LBL = number of package receivers.

  • c LBL = daily operative cost of a LBL box • c FBL = daily operative cost of a FBL unit • n FBL = number of FBL units: it equals the number of Euro ISO pallets and boxes that should be delivered • n LBL = number of LBL boxes the system operator decides to use • c v = daily cost of amortisation of a FURBOT vehicle • n v = number of required FURBOT vehicles: it depends on the overall travel time related to the delivery trips and the time at disposal for completing the freight distribution • c km = operative cost of running the fleet, for each km travelled by FURBOT vehicles: