Jean-Philippe Pernot

• Full Professor of Mechanical Engineering
• Professor (Full) at École nationale supérieure d'arts et métiers

Even if 3D acquisition systems are nowadays more and more ecient, the resulting point clouds nevertheless contain quality defects that must be taken into account beforehand, in order to better anticipate and control their eects. Assessing the quality of 3D acquisitions has therefore become a major issue for scan planning. This paper presents severa...

Malgré la grande interopérabilité des formats standards, le principal défaut de la standardisation est la perte d'informations lors de l'export des fichiers. Le format STEP contient les informations géométriques des pièces définies dans leurs modèles B-Rep, mais pas les contraintes cinématiques entre les pièces, ces informations sont donc perdues l...

The purpose of this study is to enhance point cloud semantic segmentation by using point clouds from multiple distinct technologies on the same capture location and to determine whether employing various technologies throughout the acquisition process yields better performance during classification. The different point clouds were captured in the s...

Due to its capacity to evolve in a large solution space, the Simulated Annealing (SA) algorithm has shown very promising results for the Reverse Engineering of editable CAD geometries including parametric 2D sketches, 3D CAD parts and assemblies. However, parameter setting is a key factor for its performance, but it is also awkward work. This paper...

Identification and fitting is an important task in reverse engineering and virtual/augmented reality. Compared to the traditional approaches, carrying out such tasks with a deep learning-based method have much room to exploit. This paper presents SMA-Net (Spatial Merge Attention Network), a novel deep learning-based end-to-end bottom-up architectur...

This paper introduces a novel reverse engineering technique for the reconstruction of editable CAD models of mechanical parts' assemblies. The input is a point cloud of a mechanical parts' assembly that has been acquired as a whole, i.e. without disassembling it prior to its digitization. The proposed framework allows for the reconstruction of the...

This paper introduces a new fitting approach to allow an efficient part-by-part reconstruction or update of editable CAD models fitting the point cloud of a digitized mechanical parts assembly. The idea is to make use of parameterized CAD models whose dimensional parameters are to be optimized to match the acquired point cloud. Parameters may also...

At present, optical sensors are being widely used to realize high quality control or reverse engineering of products, systems, buildings, environments or human bodies. Although the intrinsic characteristics of such breakthrough technologies may vary, ensuring complete acquisition relies on the definition of the optimal acquisition planning. To this...

Currently, geometric over-constraints detection is of major interest in several different fields. In terms of product development process (PDP), many approaches exist to compare and detect geometric over-constraints, to decompose geometric systems, to solve geometric constraints systems. However, most approaches do not take into account the key cha...

This paper addresses the way a simulated annealing-based fitting strategy can be enhanced by leveraging a sensitivity analysis able to characterize the impact of the variations in the parameters of a CAD model on the evolution of the deviation between the CAD model itself and the point cloud of the digitized part to be fitted. The principles underp...

To facilitate the transfer, storage and manipulation of intricate parts’ geometry whose fabrication has been made possible thanks to the rise of Additive Manufacturing (AM) technologies, an encoding framework reducing the resulting file size has been developed. This approach leverages the fact that many AM parts are presenting repetition patterns,...

Designing appealing products plays a key role in commercial success. Understanding the relationships between aesthetic properties and shape characteristics of a product can contribute to define user-friendly and interactive designing tools supporting the early design phases. This paper introduces a generic framework for mapping aesthetic properties...

This paper addresses the way a simulated annealing-based fitting strategy can be enhanced by leveraging a sensitivity analysis able to characterize the impact of the variations in the parameters of a CAD model on the evolution of the deviation between the CAD model itself and the point cloud of the digitized part to be fitted. The principles underp...

The fourth industrial revolution is forcing companies to rethink their status quo – creating a need to assess their digital maturity as a basis for improvements. As a result, there is a variety of maturity models available in the literature. This paper introduces a novel comparison framework designed to compare different digital maturity assessment...

This paper focuses on efficient computational optimization algorithms for the generation of µEDM tool shapes. In a previous paper, the authors presented a reliable reverse modelling approach to perform such tasks, based on a crater-by-crater simulation model and an outer optimization loop. 2D results were obtained, but 3D tool shapes proved difficu...

The use of Digital Mock-Up (DMU) has become mainstream to support the engineering activities all along the Product Development Process. Over the years, companies generate large databases containing digital models and documents related to their products. Considering complex products, the DMU can be composed of several hundred thousand parts assemble...

Following commonly used reverse engineering techniques, it is very difficult to reconstruct editable CAD parts or assemblies that can later be used and modified in the Product Development Process (PDP). Traditional methods follow a sequential time-consuming patch-by-patch reconstruction strategy with cumbersome procedures in which designers usually...

The emergence and improvement of Additive Manufacturing technologies allow the fabrication of complex shapes so far inconceivable. However, to produce those intricate geometries, support structures are required. Besides wasting unnecessary material, these structures are consuming valuable production and post-processing times. This paper proposes a...

Truss lattice structures are intricate geometries, whose fabrication has recently been simplified by the development of Additive Manufacturing (AM) technologies. These lightweight geometries present great volume densities and surface-to-occupancy ratios, which makes them ideal for thermal dissipation applications. This paper introduces a new framew...

This paper presents a new way of interaction between modelers and solvers to support the Product Development Process (PDP). The proposed approach extends the functionalities and the power of the solvers by taking into account procedural constraints. A procedural constraint requires calling a procedure or a function of the modeler. This procedure pe...

Currently, the content-based retrieval is a problem of major interest in several different fields and, focusing on mechanical engineering, many approaches exist to compare and retrieve single CAD parts, to evaluate shape similarity, to extract features and to segment models. However, most of the proposed approaches do not take into account all the...

This paper introduces a new approach for the generation of as-scanned point clouds of CAD assembly models. The resulting point clouds incorporate various realistic arti-facts that would appear if the corresponding real objects were digitalized with a laser scanner. Such a virtual Reverse Engineering technique can produce a huge amount of realistic...

Today, being able to generate and produce shapes that fit mechanical and functional requirements and having as low as possible mass is crucial for aerospace and automotive applications. Besides, the rise of new additive manufacturing technologies has widened the possibilities for designing and producing complex shapes and internal structures. Howev...

L'émergence et le développement des technologies de Fabrication Additives (FA) permet la production de formes complexes jusqu'ici inconcevables. Cependant, pour produire ces géométries tortueuses, l'ajout de structures supports est nécessaire. En plus de consommer inutilement de la matière, la fabrication de ces supports nécessite un temps de produ...

Le poster présente les premiers constats et éléments d’analyse dans le cadre du projet de génération et de traitement de nuages de points multicouches de parcelles terrestres comportant une ou plusieurs zones d’intérêts (structure, étendue d’eau, végétation, etc.).

Being able to reuse existing design knowledge is of major interest to help designers during the creation of new products. This is true at the level of the parts and even more at the level of the assemblies of multiple parts. Meaningful information and knowledge can be extracted from existing geometric models and associated data and metadata, as wel...

Aujourd'hui, tous les modeleurs géométriques de CFAO fournissent des outils pour la modélisation géo-métrique avec des contraintes. Historiquement, les contraintes géométriques en 3D ont été représentées avec des équations, et les problèmes irréductibles ont été résolus avec une variante de la méthode de Newton, ou avec la méthode d'intersection de...

Manufactured products with different purposes often include similar mechanisms to realize movements required to satisfy specific functionalities. An automatic identification of common mechanisms in assembly models would be a valuable support for analysing or reusing exiting solutions during the design process. In this paper, we present a first step...

Controlling the well-known triptych costs, quality and time during the different phases of the Product Development Process (PDP) is an everlasting challenge for the industry. Among the numerous issues that are to be addressed, the development of new methods and tools to adapt to the various needs the models used all along the PDP is certainly one o...

Today, digital data such as 2D images, 3D meshes and 3D point clouds are widely used to design virtual environments (VE). Most of the time, only one type of those multimodal data is used to describe and specify the shapes of the objects. However, a single object can be seen as a combination of components linked with constraints specifying the relat...

Easy retrieval of product data and related information is extremely important for knowledge and data reuse in new product development. Nowadays the adoption of PDM (Product Data Management) systems makes the reuse easy providing means for documenting all the data related to a product, thus making possible their retrieval through the inserted metada...

A multitude of online repositories and a large amount of specific CAD model databases are currently available. Therefore, it is crucial to have access to these data in an easy and in a multi-perspective manner according to multiple access keys, not only in terms of annotation data or shape similarity, but also in terms of specific characteristics....

Additive manufacturing offers new available categories of geometries to be built. Among those categories, one can find the well developing field of lattice structures. Attention has been paid on lattice structures for their lightweight and mechanical efficiency ratio, thus leading to more optimized mechanical parts for systems. However this lightne...

This paper proposes an original decision-support approach to address over-constrained geometric configurations in Computer-Aided Design. It focuses particularly on the detection and resolution of redundant and conflicting constraints when deforming free-form surfaces made of NURBS patches. Based on a series of structural decompositions coupled with...

Preface for the special issue of TMCE 2016 International Symposium on Tools and Methods of Competitive Engineering

La fabrication additive à ouvert le champs vers la fabrication de structures à géométrie complexe. Parmi ces structures on retrouve les structures treillis, qui ont retenues l'attention pour leur propriétés mécaniques et leur faible masse, pouvant conduire à des pièces mécaniques optimisées et légères. Cette légèreté, toutefois, ne se retrouve pas...

Even if during the Product Design Process, assembly models are described in terms of their constitutive components and associated relationships, only the position of each component is often stored within the Digital Mock-Up. Thus, the mating information are lost. However, these relationships are crucial for many applications, such as retrieval, ass...

This paper introduces a new method for simulating the micro-EDM process in order to predict both the tool’s wear and the workpiece’s roughness. The tool and workpiece are defined by NURBS patches whose shapes result from an iterative crater-by-crater deformation technique driven by physical parameters. Through hundreds of thousands of local surface...

Several approaches exist to provide Reverse Engineering solutions on mechanical parts. Mechanical assemblies and the expertise information retrieved at the same time with the model geometry are not really taken into account in the literature. Thus, the main challenge of this contribution is to propose a methodology to retrieve the Digital Mock-Up o...

Current Computer-Aided Design (CAD) packages support the storage of the final design models and solutions in different formats, and PLM software manages the high-level information about the design process, such as the versioning of the design solutions. However, the processes happening inside the CAD software are not being fully captured. Informati...

Today, designers use CAD modelers to define and modify NURBS surfaces involved in the design of complex shapes like car bodies or turbine blades. The generated shapes often result from the use of variational modeling techniques where user-specified constraints define the shapes. However, for free-form curve/surfaces, if too much constraints are add...

Today, there exists a huge amount of digital data easily downloadable from Internet and/or simply accessible from large databases. Despite this rise, the methods to retrieve and search for specific data have not been sufficiently studied and developed, notably when considering 3D contents. Thus, it is sometime more efficient to define new 3D shapes...

With the rise of additive manufacturing, complex internal structure optimization is now a relevant topic. Additive manufacturing allows designers and engineers to go further in their modeling, designing and optimization process, allowing new complex shapes to be produced, including the optimization of their internal structure. However modeling, des...

The prediction of the tool wear phenomenon in the micro electro discharge machining technology would be of a great use in the optimization of tool shapes. In order to do so, the ability to rapidly and precisely simulate the process is required. The choice of a geometrical model for the electrodes is of the utmost importance as it will condition the...

Today’s CAD modelers are very efficient in processing 3D shapes of CAD models by means of B-Rep modeling operators such as pad, pocket, shaft, groove, hole, fillet and so on. At a lower description level, those modeling operators are based on Euler operators acting directly on the faces, edges and vertices of the B-Rep models. Using such a top-down...

Being able to estimate a priori the impact of DMU preparation scenarios for a dedicated activity would help identifying the best scenario from the beginning. Machine learning techniques are a means to a priori evaluate a DMU preparation process without to perform it by predicting its criteria of evaluation. For that, a representative database of ex...

CAD modelers enable designers to construct complex 3D shapes with high-level B-Rep operators. This avoids the burden of low level geometric manipulations. However a gap still exists between the shape that the designers have in mind and the way they have to decompose it into a sequence of modeling steps. To bridge this gap, Variational Modeling enab...

This paper presents a new approach for the recording of the total quantity of energy exchanged during the micro electrical discharge machining (EDM) process. In particular, this approach allows for the estimation of the percentage of energy absorbed by the two electrodes (tool and workpiece) using a combination of theoretical models and experimenta...

Purpose – The purpose of this paper is to focus on the characterization and classification of parts with respect to the meshing issue, and notably the meshing of thin parts difficulty handled automatically and which often requires adaptation steps. The objective is to distinguish the so-called thin parts and parts with thin features from the other...

Purpose – The purpose of this paper is to set up a new framework to enable direct modifications of volume meshes enriched with semantic information associated to multiple partitions. An instance of filleting operator is prototyped under this framework and presented in the paper. Design/methodology/approach – In this paper, a generic mesh modificat...

Le principe de la modélisation déclarative est d'engendrer des formes par la description d'un ensemble de propriétés. Les propriétés sont décrites sous la forme d'une liste d'énoncés intuitifs, si possible proches du langage naturel. Un procédé automatisé permet ensuite de fournir une solution conforme aux spécifications données. Nous proposons d'a...

Nowadays, it is commonly admitted that the aesthetic appearance of a product has an enhanced role in its commercial success. Therefore, understanding and manipulating the aesthetic properties of shapes in the early design phases has become a very important field of research. There exists an appropriate vocabulary for describing the aesthetic proper...

Reverse-Engineering techniques are commonly used to generate or update the CAD model of a single physical object. However, the reverse engineering of a whole assembly is still very tedious and time-consuming. This is mainly due to the fact that the complete definition of the final digital mock-up relies on the integration of multiple sources of het...

Since the quality of FE meshes strongly affects the quality of the FE simulations, it is known to be very important to generate good quality meshes. Thus, it is crucial to be able to estimate very early what can be the expected quality of a mesh without having to play in loop with several control parameters. This paper addresses the way the quality...

Essential when adapting CAD model for finite element analysis, the defeaturing ensures the feasibility of the simulation and reduces the computation time. Processes for CAD model preparation and defeaturing tools exist but are not always clearly formalized. In this paper, we propose an approach that uses machine learning techniques to design an ind...

The complete product definition can be seen as the result of a process where all the various requirements (functional, aesthetic, economical, feasibility, and so on) are satisfied at the best. For this reason the Product Design Process (PDP) involves many actors, tasks, and activities, currently supported by dedicated IT tools such as: computer-aid...

Numerical simulations play more and more important role in product development cycles and are increasingly complex, realistic and varied. CAD models must be adapted to each simulation case to ensure the quality and reliability of the results. The defeaturing is one of the key steps for preparing digital model to a simulation. It requires a great sk...

The construction of a Virtual Environments (VE) requires a long iterative modeling and modification process. Depending on the final purposes, many actors can be involved both in the early conception and in the detailed specification of what has to be included and how it has to be organized. These actors may have different knowledge and expertise. I...

This paper introduces a new method for simulating the micro-EDM process in order to predict tool wear. The tool and workpiece are defined by NURBS surfaces whose shapes result from an iterative crater-by-crater deformation technique driven by physical parameters. The simulation method is validated through a comparison with experimental data. Differ...

Data exchanges between different software are currently used in industry to speed up the preparation of digital prototypes for finite element analysis (FEA). Unfortunately, due to data loss, the yield of the transfer of manifold models rarely reaches 1. In the case of non-manifold models, the transfer results are even less satisfactory. This is par...

World-wide market competition and the need to create products that better satisfy the market expectations require a more comprehensive involvement of the customer in the product definition loop. Therefore, it is crucial to provide customers with very easy-to-use shape definition and modification tools, allowing them to verify and evaluate possible...

Reverse-Engineering techniques are commonly used to generate or update the CAD model of a single physical object. However, the reverse engineering of a whole assembly is still very tedious and time-consuming. This is mainly due to the fact that the complete definition of the final digital mock-up relies on the integration of multiple sources of het...

Aujourd'hui, la construction d'un Environnement Virtuel (EV) résulte d'un long processus itératif de modélisation et de modification. Il n'existe pas de liens forts entre les différents acteurs du processus de génération d'EVs, les différents outils utilisés et les modèles géométriques manipulés. Ainsi, la chaine numérique se trouve rompue. A chaqu...

Nowadays, the aesthetic plays a key role in the commercial success of a product. Thus, in the last year, the aesthetic properties of curves have been widely studied and an appropriate vocabulary has been identified together with a set of mathematical models used to quantify the aesthetic of free form curves. This work investigates the possibility o...

Nowadays, industrial CAD models databases are becoming larger and larger, thus inaugurating new challenges for their management during the product design process. Unfortunately, neither the PDM nor PLM systems are good at indexing and sorting CAD models according to their content, and it is sometime more efficient to redesign a part than to try to...

Currently adopted process from Computer-Aided Design (CAD) product definition to numerical simulation could be improved by avoiding the return to the CAD model for model modification. To this aim, we propose a generic mesh modification operator whose architecture is detailed in this paper. A new instance of this operator for filleting finite elemen...

Dans cet article, nous décrivons une démarche méthodologique visant à proposer et caractériser des stratégies de traitement et de simplification de la maquette numérique d’un produit en vue de faciliter l’exploitation de celle-ci pour des activités de simulation numérique et de visualisation. La finalité sera l’accélération des itérations de concep...

Durant la phase d'acquisition de points du processus de rétro-conception, si un objet possède des formes complexes, ou si ses surfaces extérieures sont inaccessibles, certaines zones peuvent ne pas être capturées. Ces déficiences dans le nuage de points se traduisent par des trous dans le maillage reconstruit. Les travaux présentés dans cet article...

This paper presents a novel approach for constrained B-Spline curve approximation based on the Force Density Method (FDM). This approach aims to define a flexible technique tool for curve fitting, which allows approximating a set of points taking into account shape constraints that may be related to the production process, to the material or to oth...