Alexandre Voisin

Subjective evaluation of car seat comfort with fuzzy set techniques

Subjective evaluation is a central problem in the life cycle of most products. Automotive companies use subjective evaluation of car seat comfort to check the adequacy between specifications and effective realization. A great deal of time and money are spent to achieve this goal. To solve these problems, our projects goal is to save the expert knowledge and to automate this phase in order to achieve more flexibility. This article presents some of the first steps in saving the expert know‐how in addition to help for decision making. We propose tools for the expert assessment acquisition and processing using a fuzzy set technique called expertons. Expertons are applied to a typical example related to our application. It emphasizes the suitability of expertons for the help for decision making.

A proactive condition-based maintenance strategy with both perfect and imperfect maintenance actions

This paper deals with a proactive condition-based maintenance (CBM) considering both perfect and imperfect maintenance actions for a deteriorating system. Perfect maintenance actions restore completely the system to the ‘as good as new’ state. Their related cost are however often high. The first objective of the paper is to investigate the impacts of imperfect maintenance actions. In fact, both positive and negative impacts are considered. Positive impact means that the imperfect maintenance cost is usually low. Negative impact implies that (i) the imperfect maintenance restores a system to a state between good-as-new and bad-as-old and (ii) each imperfect preventive action may accelerate the speed of the system׳s deterioration process. The second objective of the paper is to propose an adaptive maintenance policy which can help to select optimally maintenance actions (perfect or imperfect actions), if needed, at each inspection time. Moreover, the time interval between two successive inspection points is determined according to a remaining useful life (RUL) based-inspection policy. To illustrate the use of the proposed maintenance policy, a numerical example finally is introduced.

Group fuzzy AHP approach to embed relevant data on “communicating material”

Abstract The amount of data output into our environment is increasing each day, and the development of new technologies constantly redefines how we interact with information. In the context of product life cycle management, it is not uncommon to use intelligent products to ensure an information continuum throughout the product life cycle (e.g., for traceability purposes). Integrating intelligence and information into products themselves is now possible through numerous technologies (RFID, communicating materials). However, these technologies currently have low memory capacities (several kilobytes or megabytes), whereas to product databases are becoming larger and larger (several gigabytes or terabytes). As a result, a data dissemination process is required to determine the relevant information that should be stored on the product. This paper proposes a multiple-criteria decision-making (MCDM) method based on a fuzzy Analytical Hierarchy Process (fuzzy AHP). This method is context-aware and supports the aggregation of opinions from a group of experts. An application is proposed to embed context-sensitive information in a “communicating textile”.

Method for embedding context-sensitive information on “communicating textiles” via fuzzy AHP

The amount of data output in our environment is increasing each day, and the development of new technologies constantly redefines how we interact with information. In the context of PLM Product Lifecycle Management, it is not uncommon to use intelligent products to ensure an information continuum all along the product life cycle e.g. for traceability purposes. However, it is not that easy to identify what information should be stored on the product. To answer this question, this paper proposes a data dissemination process to select context-sensitive information from the database, that must be stored/replicated on the product especially if the product is made of “communicating material”. Our approach uses the fuzzy AHP theory for aggregating points of view from different actors. The data dissemination process is then applied on a case study to embed context-sensitive information on a “communicating textile”.

Remaining useful life (RUL) based maintenance decision making for deteriorating systems

This paper deals with a remaining useful life (RUL) based maintenance policy for single unit deteriorating systems whose condition are periodically monitored. Thank to the RUL information, which is estimated from the available monitoring information, various decisions related to inspections, logistic support, maintenance opportunities and maintenance actions are considered in the proposed policy. To illustrate the use and the advantages of the proposed maintenance policy, different sensitivity studies are analyzed and discussed through a numerical example. A comparaison with a classical condition based maintenance policy is also investigated.

Evaluation of a sensory measurement fuzzy system for car seat comfort

This article presents the evaluation of a sensory measurement fuzzy system intended for the design of car seat comfort. This system is based on the processing of pressure images obtained from the seat-driver interaction measurement. The system gives fuzzy values of the seat sensory characteristics. For the validation, we compare the order given by seat evaluators with the one obtained from the fuzzy ordering operators applied on the measurements.

Sensory features measurement of the under-thigh length of car seat

Feature evaluation is a central process in the life cycle of a product. When a human performs this process, it is called sensory evaluation. This field is well formalized. It has been introduced in food companies and is beginning to enter others, such as automotive companies. Our work intends to build an artificial system to be used in the place of humans in car seat comfort evaluation. We present our contribution to the acquisition of sensory features of the seat. We define a system that processes a pressure map of the man-seat interface into the value of the stimulated seat feature represented by a possibility distribution.

Industrial demonstrations of e-maintenance solutions

The aims of some industrial demonstrations were to integrate the technological and information technology strands in a business sense and to verify the effectiveness of the complete DynaWeb solution, i.e.: Assessment of functionality and robustness of the complete hardware and software system developed in the different parts of the project. Assessment of the e-maintenance concept and strategy and the costeffectiveness model developed in the project, which is presented in the previous chapters in this book. To test the developed methods for optimising maintenance strategies and technology choices using real data, providing the benchmarks against which the research is measured. To demonstrate the effectiveness of new strategies and cost effectiveness on field data. Assessment of user interface, i.e., the usability of DynaWeb combined with assessment of training modules. Identification of the best practice and meeting the needs in training and education for technical, IT and management in maintenance. The results of research have been integrated in new courses.

Bottom-up capacities inference for health indicator fusion within multi-level industrial systems

In Prognostics and Health Management (PHM) considerations, data fusion technique is a corner step as it enables gathering non homogeneous condition information to provide a synthesizing view on component situations. Nevertheless with regards to complex industrial systems, efficient health monitoring should be addressed not only at component level but also at higher system abstraction levels since the decision making procedure relies on the global industrial system state. To face this issu e, one way consists first in gathering, in the form of vector, the different indicators carrying most important health information related to each system function. Then, a health state has to be computed by fusing each indicator vector taking into account their relevance and their relationships in accordance with the considered system level. It is proposed in this paper to use Choquet integral as an aggregation operator to support this health state development for each function within the system breaking up. It implies to formalize the capacities (Choquet integral parameters) from a bottom-up approach allowing to infer capacities of each system function from those computed at component level. It leads to trace the relevance of health information across the system levels. The feasibility and interest of this fusion approach are shown on an application structured with two system levels.

Choquet integral parameters inference for health indicators fusion within multi-levels industrial systems: application to components in series

Data fusion is a cornerstone step for monitoring component health state within a prognostics and health management (PHM) vision. It enables gathering disparate health information in order to build a global view for the situation evolving over time. Nevertheless for complex systems, efficient health monitoring should be addressed not only at component level but also at higher system abstraction levels since the decision making procedure rely on the global industrial system state. Herein, a novel approach based on the computation of a health index at each system layer function by fusing values within its related indicator vector is proposed. The fusion operator used for this approach is the Choquet integral that requires identifying capacities (Choquet integral parameters) for each function within the system decomposition. In order to take into account relationships between functions in accordance with the considered system layer, a bottom-up approach allowing inferring capacities of each system function from those computed at component level is introduced. This work is the follow-up of a previous one dealing with the case of system elements arranged in parallel. The feasibility and interest of this approach are shown on an application structured with two system layers.