Zugl.: Aachen, Techn. Hochsch., Diss., 2009

Proefschrift Rijksuniversiteit Groningen. / Met lit.opg.

La préhension manuelle est une des habilités de l’homme la plus développée et la plus utilisée dans la vie de tous les jours. Cette capacité nous permet de saisir et de manipuler des objets dans des configurations aussi nombreuses que complexes. Malheureusement, la main est aussi le siège de nombreuses blessures qui, de par l’importance de la préhension, sont fortement handicapantes. Face à ce constat, comprendre les contraintes mécaniques qui sont exercées dans les muscles, les tendons, les articulations et les ligaments lors de gestes de la vie quotidienne apparaît comme un enjeu majeur pour la prévention, la réhabilitation et l’ergonomie. L’objectif de ce travail doctoral était de développer un modèle biomécanique de la préhension permettant une estimation de ces variables non mesurables. A titre d’exemple,le paradigme de la pince pouce-index a été utilisé. Dans une première étude, les modèles biomécaniques de la pince disponibles dans la littérature ont été développés et comparés.Suite à cette évaluation, il a été constaté que ces modèles, en particulier le pouce,nécessitaient des améliorations pour permettre une évaluation physiologiquement réaliste lors de la préhension. Dès lors, plusieurs améliorations ont été proposées. Premièrement, une procédure expérimentale a été développée afin d’évaluer et d’inclure les participations mécaniques passives (ligaments, tissus mous, butées osseuses) de l'articulation trapèzométacarpienne. Deuxièmement, des mesures effectuées par IRM ont été utilisées afin d’intégrer l’action mécanique du muscle First Dorsale Interosseous dans l’équilibre du pouce,ce muscle étant alors négligé malgré son importance dans les tâches de préhension.Troisièmement, une méthode expérimentale permettant d’évaluer plus facilement et plus précisément, in situ, les axes de flexion/extension et d’adduction/abduction de l’articulation trapèzométacarpienne a été proposée et évaluée. Enfin, le modèle biomécanique incluant ces améliorations a été mis en œuvre dans une dernière étude ergonomique visant à étudier l’effet de la taille de l’objet manipulé sur les forces musculaires et articulaires. / Manual precision grip is one of man's most developed and most used ability in everyday lifeactivities. The negative outcome is the high exposure of the hand to repetitive stress injurieswhich are often very disabling. Thus, the understanding of the mechanical stress exerted inmuscles, tendons, joints and ligaments during gripping tasks appears as a major issue forinjury prevention, rehabilitation and ergonomic considerations. This doctoral work aimed atdeveloping a biomechanical model of the grip to estimate the unmeasurable internal loads. Asan example, the classical paradigm of the thumb - index finger grip was used. In a first study,the biomechanical models of the thumb available in the literature were compared and severalimprovements proposed in order to obtain more physiologically realistic predictions. First, anexperimental method was developed to evaluate and include passive structures moment intothe equilibrium of the trapeziometacarpal joint (TMC). Secondly, MRI was used to integratethe mechanical action of the First Dorsal Interosseous muscle at the TMC, since this musclehas commonly been neglected in thumb models but seems essential during pinch grip.Thirdly, the kinematic model which has to be used with the anthropometric data of tendonmoment arms was evaluated and compared to our proposition of a functional method toassess, in situ, the axes of rotation of the TMC. Finally, the biomechanical model includingthese improvements was implemented in an ergonomic study. We investigated the effect ofobject width on grip forces and muscles/joints loads. This doctoral work finds its consistencyin its desire to develop and apply the biomechanical modelling of the hand in the fields ofclinical and ergonomics.

Le tennis elbow est une pathologie fréquente affectant le membre supérieur. Cette pathologie s'observe également dans un large éventail d'activités manuelles allant de la manipulation d'outils de maçonnerie à la manipulation d'une souris d'ordinateur. Malgré son prévalence élevée, les mécanismes sous-jacents au développement du tennis elbow demeurent paradoxalement largement méconnus et n'offrent pas de consensus scientifique. Toutefois, les outils, les instruments ou les objets manipulés, formant une interface avec la main, sont soupçonnés d'être en partie responsables de l'apparition de cette affection. Cependant, le manque de moyens d'investigation biomécanique sur la main ramène cette assertion au statut d'hypothèse. Dans ce travail de thèse, l'idée que les caractéristiques physiques de la raquette (i.e. taille et forme du manche ; inertie de la raquette) puissent avoir une influence sur le risque d'apparition du tennis elbow a été testée. Pour cela, nous avons mené une démarche structurée en trois étapes. Tout d'abord, une approche expérimentale contrôlée nous a permis de quantifier les efforts exercés au niveau de l'interface main-manche lorsque l'on serre simplement ce dernier. Pour cela, un instrument de mesure des forces a été développé (i.e. ergomètre à 6 poutres couplé à une nappe de pression Tekscan). Cela nous a permis de définir une taille et une forme de manche optimale pour les forces de serrage. Dans un second temps, ce manche optimal (i.e. de section circulaire et de périmètre égal à 17,9% de la longueur de la main) a été testé au cours de frappes de tennis. / Lateral epicondylalgia (LE) have been reported to occur at least once in a range of 40% to 50% of tennis players and in a large number of workers using hand tools. Despite high prevalence, the mechanisms underlying the development of tennis elbow are paradoxically misunderstood and suffer from a lack of scientific consensus. The characteristics of the handled tools (e.g. the grip size and the shape) are believed to be partly responsible for the occurrence of these disorders. However, the available material and technique for investigation and the proceedings studies did not gave evidence for this hypothesis. In this work, the idea that the size and shape of a tennis racket handle can affect the risk of developing tennis elbow was tested in three main steps. First, a controlled experimental approach was performed in order to quantify the forces exerted at the interface hand / handle when squeezing simply a handle. A special force ergometer has been developed to measure the forces at the hand/handle interface. This study enabled us to define an optimal size and shape (i.e. circular perimeter equal to 18% of the length of the hand) to perform a maximal squeezing force. In a second step, the optimal handle was tested during tennis strokes. Our results show that with and without fatigue, the grip force was lower for the optimal handle compared to bigger or smaller handle. Finally, in a last step, a biomechanical model of the hand was used to assess the impact of the tennis racket grip size on the forces applied on muscles affected by tennis elbow during a simulation. Our results suggest that the optimal grip size reduces muscle tensions of hand extensor muscle.

The topic of this thesis is design apartment for a young couple and a proposal dining table. The result of the work has to be room in which the two young people to live well and the dining table that is conceived in an unusual way. For interior design was needed to become familiar with individual rooms and steam requirements, choose the right colors and furniture arrangement. The proposal dining table is also associated with knowledge, not only historical, but also knowledge of requirements such as security, drawings, designs and dimensions, material. The result is a modern apartment interior design for specific partners and dining table simple lines with shelves.

The theme of the dissertaion is appliaction of mechatronics in seating furniture. The work defines the principles of mechatronics and presents samples of the existing applications of mechatronics in interior furnishing elements. The work describes the current status of the positioning of seating furniture and systematically devides particular positioning elements according to construction principles and function in term of changes in the ergonomic parameters of positioning furniture. In this description are captured current trends of progress in positioning of seating furniture with mechanical and electrical drive. The work defines the basic functional parts of the positioning mechanisms: guiding system, electric motors, control system, safety elements. The work specifies the logical elements that elevate electromechanical applications from mechatronic application. The aim of the work is the formulation of potential areas of application of Mechatronics in the sitting furniture. The work contains a theoretical vision and specific suggestions for application of mechatronics in the sitting furniture, complemented by proposals without the application of mechatronics.

My thesis has dealt with the topic of impact of work environment on employee motivation in the selected company and its aim was to briefly literally introduce the issue of human resources and personnel management conditions, further to shed a light on the importance of ergonomics and the impact of working conditions on employees' motivation as well as their subsequent remuneration options. The methodology part includes the interviews with employees of the selected company, which were needed to determine primary information and follow-up survey, where the topic of the impact of working conditions on staff motivation and performance was specified. The outcome of the thesis is to propose innovative improvement measures leading to positive changes in the area of human resource management. This ought to result in the improvement of both the physical condition of workers and their satisfaction and motivation to administer the best possible job performance; not only currently, but even henceforth. All proposals for improving are processed with an approximate cost of the realization in case of potential interest, which has been significantly shown by company Unterer Ltd.

Un des buts de l'ergonomie est de participer à la conception des systèmes humain-machine. Il est largement reconnu que la contribution de l'ergonomie doit intervenir le plus tôt possible dans le processus de conception, depuis la découverte des besoins des utilisateurs jusqu'à la définition des exigences et des spécifications de conception, c'est-à-dire dès l'analyse des besoins. L'objectif de la thèse est d'analyser notre propre participation, en tant qu'ergonome co-concepteur, à l'analyse des besoins d'un projet de conception d'EDF R&D concernant un nouveau système informatique pour le pilotage de réacteurs nucléaires. Au cours de celui-ci, nous avons collaboré avec les ingénieurs du projet et les futurs utilisateurs dans la définition des différents aspects du système (fonctionnel, organisationnel, opérationnel, interaction et physique) à travers la formulation d'exigences et de spécifications. Cette collaboration s'est cristallisée à travers la rédaction du cahier des charges final. Outre l'observation de notre intervention dans le projet, trois études empiriques ont été menées. Dans chacune d'elles, notre rôle spécifique à différentes étapes de l'analyse des besoins est analysé par rapport aux rôles des ingénieurs et des utilisateurs. La première étude détaille notre contribution à l'identification et à la formalisation des exigences. La seconde étude analyse notre concours à la rédaction des spécification. Enfin, la troisième étude met en lumière notre participation à l'évolution de la première version des exigences et des spécifications jusqu'à leur version définitive. L'ensemble de ces travaux indique plusieurs résultats importants. Premièrement l'ergonome co-concepteur ne doit pas se limiter à ce statut pour agir globalement sur la situation de travail. Deuxièmement, contrairement à ce qu'indique la littérature, les étapes de l'analyse ergonomique des besoins sont plutôt réalisées en parallèle que de manière séquentielle. Troisièmement, l'ergonome va privilégier des contacts différents selon les phases de l'intervention. Il sera plutôt en contact avec les futurs utilisateurs lors de l'identification des besoins et surtout en lien avec l'équipe de conception lors des phases de spécification. Cependant, dans ces phases ultérieures, les séances de travail avec les utilisateurs font plus évoluer le système que les autres séances de travail. Quatrièmement, les études montrent que les différents acteurs impliqués ont un domaine d'expertise spécifique, mais complémentaire, aussi bien pour définir les exigences que les spécifications. Par exemple, dans la définition des spécifications, l'ergonome va formuler les éléments du système accessibles à l'utilisateur alors que les ingénieurs vont spécifier les éléments techniques nécessaires au fonctionnement, mais inaccessibles aux utilisateurs. Enfin, les résultats indiquent que l'ergonome ne s'appuie pas uniquement sur les éléments recueillis lors des analyses de terrain pour produire des exigences et des spécifications. Les analyses de terrain ont surtout été utilisées pour justifier les aspects fonctionnels, organisationnels et opérationnels du système. A contrario, les spécifications de l'interface du système proviennent plutôt de son expertise. Enfin, nous proposons une méthode ergonomique d'analyse des besoins. Par rapport aux méthodes actuelles, celle-ci met davantage l'accent sur les aspects collectifs de ce type d'intervention et détaille les apports de l'ergonome à la définition des différentes dimensions du système. / One of the goals of ergonomics is to contribute to the design of man-machine systems. It is widely recognized that the involvement of ergonomics must take place as early as possible in the design process, starting with the discovery of user needs, up to the definition of design requirements and specifications - i.e. from user needs analysis onwards. The thesis aims to analyze our own participation, as an ergonomist and a co-designer, to user needs analysis in a design project at the EDF R&D department. The project dealt with a new computer system to operate nuclear reactors. During this work, we collaborated with engineers from the project and with future users, to define various aspects of the system (functional, organizational, operational, interaction-based, and physical) byformulating requirements and specifications. This collaboration materialized in the final specifications. In addition to observing our own involvement in the project, we carried out three empirical analyzed, in contrast to the roles of engineers and end users. The first study describes our contribution to identifying and formalizing user requirements. The second study analyses our role in writing the system specifications. Finally, the third study highlights our participation to the evolutions of the first version of requirements and specifications, towards their final version. This work has led to several important results. First, ergonomist as a co-designer should not restict his participation to this status, and should instead act globally on the work situation. Second, in contrast to claims in the literature, the stages of ergonomic needs analysis are carried out simultaneously rather than sequentially. Third, ergonomists tend are more often in contact with end users during user needs identification and more often in contact with the design team during the stage of system specification. However, in these later stages, work sessions with end users allow the system to evolve more than in other types of work sessions. Fourth, the studies show that the various stakeholders involved each have a specific field of expertise. These fields of expertise complement the expertise of ergonomics, both when defining requirements and when defining system specifications. For example, when defining specifications, ergonomists formulate the set of system elements which are accessible to users, whereas engineers specify the set of technical elements which are necessary to system operation, which are inaccessible to users. Finally, our results show that the ergonomist does not rely solely on elements gathered in field investigations to produce requirements and specifications. Field analyses are most often used to tackle the functional, organizational, and operational aspects of the system, whereas defining the elements of the system interface relies more on the ergonomist's own expertise. Finally, we propose an ergonomic method for user needs analysis. Compared with current methods, our method highlights the collective aspects of such interventions, and specifies the contributions of ergonomics to defining the various dimensions of a system.

The world statistics state that 80% of the population encounter pains in the back. These problems were accelerated by modern times, that thanks, to the technical comfort, brought to many people health troubles resulting from the lack of exercise. I chose the subject {\clqq} Training of the back`` because I work as physiotherapist and the people feeling pains in the back belong to my profession every day. I occupy myself with the given problems. Considering the present state of the given problems, I concentrated on the most important connection concerning the training of the back. First, I described the backbone as a part of the locomotory system. Another guideline that was interconnection of muscular groups of the back, chest, abdomen and of the pelvis, that build the muscular corset. I described locomotory stereotypes and disorders there of in particular relations. Integral part of the present state that is the origin of the pain, its cause, diagnosis and therapy. In the theoretical part I dealt with general principles as to the training of the back and with the importance of this training for the therapy of vertebrogenous patients. The aim of the work and of the research was to discover whether a change in locomotory stereotypes before and after therapy took place at patients with pains in lumbosacral part of the backbone and to propose for three different professions the therapy inclusive of necessary regiment measures. The hypothesis was proclaimed that the therapy including also the training of the back will bring about the change locomotory habits of the patients. Secondary analysis of data from health documentation in combination with directly watching the patents were used as technology of the research. The last form of the research is the questionnaire interviewing of the patients suffering from pains in the lumbosacral part of the backbone. It concerns an integral research with prevailing technologies of quantitative research. The basic check group, that are clients of the physiotherapeutical clinic, who suffer from back pains in the lumbosacral part of the backbone. 100 patients altogether underwent the therapy. They were given the same number of questionnaires. All of them were returned. Theoretical questionnaire investigation was under way from October 2007 to March 2008. I used diagrams in processing the collected data and show the results in percentages. I chose three different professions in the course of therapy, and that secretary, forester and student doing sport and I proposed for them the therapy of back pain, that included also the training of their backs and regimen measures as pain prevention. The proclaimed hypothesis was confirmed in connection with the aim of the work. The research work, I carried out, present analysis of particular locomotory stereotypes. The results showed that locomotory habits had been improved after the therapy in direction to psychology. If the patients observe the stereotypes, they learnt and continue the physiotherapy, I chose, and the part of which is also the training of the back, helped not only the patients themselves, but that it brought benefit for the whole physiotherapeutical clinic. The work will be exploited for organization of seminars on the given place of work.

Ce travail de thèse s’inscrit dans le cadre du développement des mannequins numériques pourl’évaluation ergonomique de la conception de véhicule, plus particulièrement des commandesautomobiles. Il vise à développer des modèles biomécaniques permettant la prise en comptede la dynamique du mouvement et de la force exercée lors d’une tâche pour prédire lemouvement et l’inconfort associé. Ce travail s’est focalisé sur la pédale d’embrayage.Concernant le développement des critères d’inconfort, le concept du mouvement neutre estexploré. Une méthode, basée sur la comparaison entre des mouvements avec desconfigurations imposées et ceux moins contraintes, est proposée. Elle a permis l’identificationde paramètres biomécaniques pertinents et de proposer des indicateurs d’inconfort pour laconception de la pédale d’embrayage.Les relations entre la posture et la force d’appui ont été étudiées expérimentalement en faisantvarier le niveau d’effort exercé sur une pédale statique. Nos résultats montrent que la directiond’effort et l’ajustement postural suivent le principe de minimisation des couples articulaires.Par ailleurs l’utilisation d’un critère de minimisation de l’activité musculaire a montré uneamélioration de la prédiction de la direction d’effort pour les efforts peu élevés.Les indicateurs d’inconfort proposés dans cette étude fournissent des informations objectivespermettant aux ingénieurs de conception de comparer des solutions alternatives de design. Letravail sur les mécanismes de contrôle de l’effort et de la posture constitue, quant à lui, unepremière étape dans l’optique de prendre en compte la force exercée dans la simulation deposture. / This thesis takes place in the context of the development of digital human models forergonomic assessment of vehicle design, particularly automotive controls. It aims to developbiomechanical models that can take into account the dynamics of movement and the forceexerted during a task to predict the movement and the associated discomfort. This workfocused on the clutch pedal.For the development of the discomfort criteria, the concept of neutral movement is explored.An approach, based on comparing imposed pedal configurations and less constrained pedalconfigurations movements, has been proposed. It allowed the identification of relevantbiomechanical parameters and to propose indicators of discomfort for the design of the clutchpedal.The relationships between posture and force exertion were studied experimentally by varyingthe level of force exerted on a static pedal. Our results show that the direction of forceexertion and the postural adjustment follow the principle of minimization of joint torques.Furthermore, the use of a criterion for minimizing muscle activity showed an improvement inpredicting the direction of effort for the low and intermediate force levels.Discomfort indicators proposed in this study provide objective information that allows designengineers to compare design alternatives. Work on the control mechanisms of force exertionand posture is, in turn, a first step towards the simulation of posture/movement by taking intoaccount force exertion.