Le thème central de cette thèse est la conception d’actionneurs doux à partir de matériaux intelligents et d’une prothèse de main robotique souple. Notre approche prends en compte les différents points qui peuvent influer sur le développement d’une stratégie d’actionnement ou d’un muscle artificiel : i) Les mécanismes et la fonctionnalité de la main humaine afin d’identifier les exigences fonctionnelles pour une prothèse de main robotique en matière de préhension. ii) L’analyse et l’amélioration des mécanismes de la main robotique pour intégrer un comportement souple dans la prothèse. iii) L’évaluation expérimentale de la prothèse de main robotique afin d’identifier les spécifications du système d’actionnement nécessaire au fonctionnement cinématique et dynamique du robot. iv) Le développement et la modélisation d’une stratégie d’actionnement utilisant des matériaux intelligents.Ces points sont abordés successivement dans les 4 chapitres de cette thèse1. Analyse du mouvement de la main humaine pour l’identification des exigences technologiques pour la prothèse de main robotique.2. Conception et modélisation de la prothèse de main robotique à comportement souple.3. Evaluation mécatronique de la prothèse de main.4. Conception d’un muscle artificiel basé sur des matériaux intelligents. / In the field of robotic hand prosthesis, the use of smart and soft materials is helpful in improving flexibility, usability, and adaptability of the robots, which simplify daily living activities of prosthesis users. However, regarding the smart materials for artificial muscles, technologies are considered to be far from implementation in anthropomorphic robotic hands. Therefore, the target of this thesis dissertation is to reduce the gap between smart material technologies and robotic hand prosthesis. Five central axes address the problem: i)identification of useful grasping gestures and reformulation of the robotic hand mechanism, ii) analysis of human muscle behavior to mimic human grasping capabilities, iii) modeling robot using the hybrid model DHKK-SRQ for the kinematics and the virtual works principle for dynamics, iv) definition of actuation requirements considering the synergy between prehension conditions and robot mechanism, and v) development of a smart material based actuation system.This topics are addressed in four chapters:1. Human hand movement analysis toward the hand prosthesis requirements2. Design and modeling of the soft robotic hand ProMain-I3. Mechatronic assessment of Prosthetic hand4. Development of an artificial muscle based on smart materials

Cette thèse s’intéresse à la modélisation et à la commande de robots déformables, c’est à dire de robots dont le mouvement se fait par déformation. Nous nous intéressons à la conception de lois de contrôle en boucle fermée répondant aux besoins spécifiques du contrôle dynamique de robots déformables, sans restrictions fortes sur leur géométrie. La résolution de ce défi soulève des questions théoriques qui nous amènent au deuxième objectif de cette thèse: développer de nouvelles stratégies pour étudier les systèmes de grandes dimensions. Ce manuscrit couvre l’ensemble du développement des lois de commandes, de l’étape de modélisation à la validation expérimentale. Outre les études théoriques, différentes plateformes expérimentales sont utilisées pour valider les résultats. Des robots déformables actionnés par câble et par pression sont utilisés pour tester les algorithmes de contrôle. A travers ces différentes plateformes, nous montrons que la méthode peut gérer différents types d’actionnement, différentes géométries et propriétés mécaniques. Cela souligne l’un des intérêts de la méthode, sa généricité. D’un point de vue théorique, les systèmes dynamiques à grande dimensions ainsi que les algorithmes de réduction de modèle sont étudiés. En effet, modéliser des structures déformables implique de résoudre des équations issues de la mécanique des milieux continus, qui sont résolues à l’aide de la méthode des éléments finis (FEM). Ceci fournit un modèle précis des robots mais nécessite de discrétiser la structure en un maillage composé de milliers d’éléments, donnant lieu à des systèmes dynamiques de grandes dimensions. Cela conduit à travailler avec des modèles de grandes dimensions, qui ne conviennent pas à la conception d’algorithmes de contrôle. Une première partie est consacrée à l’étude du modèle dynamique à grande dimension et de son contrôle, sans recourir à la réduction de modèle. Nous présentons un moyen de contrôler le système à grande dimension en utilisant la connaissance d’une fonction de Lyapunov en boucle ouverte. Ensuite, nous présentons des algorithmes de réduction de modèle afin de concevoir des contrôleurs de dimension réduite et des observateurs capables de piloter ces robots déformables. Les lois de contrôle validées sont basées sur des modèles linéaires, il s’agit d’une limitation connue de ce travail car elle contraint l’espace de travail du robot. Ce manuscrit se termine par une discussion qui offre un moyen d’étendre les résultats aux modèles non linéaires. L’idée est de linéariser le modèle non linéaire à grande échelle autour de plusieurs points de fonctionnement et d’interpoler ces points pour couvrir un espace de travail plus large. / This thesis focuses on the design of closed-loop control laws for the specific needs of dynamic control of soft robots, without being too restrictive regarding the robots geometry. It covers the entire development of the controller, from the modeling step to the practical experimental validation. In addition to the theoretical studies, different experimental setups are used to illustrate the results. A cable-driven soft robot and a pressurized soft arm are used to test the control algorithms. Through these different setups, we show that the method can handle different types of actuation, different geometries and mechanical properties. This emphasizes one of the interests of the method, its genericity. From a theoretical point a view, large-scale dynamical systems along with model reduction algorithms are studied. Indeed, modeling soft structures implies solving equations coming from continuum mechanics using the Finite Element Method (FEM). This provides an accurate model of the robots but it requires to discretize the structure into a mesh composed of thousands of elements, yielding to large-scale dynamical systems. This leads to work with models of large dimensions, that are not suitable to design control algorithms. A first part is dedicated to the study of the large-scale dynamic model and its control, without using model reduction. We present a way to control the large-scale system using the knowledge of an open-loop Lyapunov function. Then, this work investigates model reduction algorithms to design low order controllers and observers to drive soft robots. The validated control laws are based on linear models. This is a known limitation of this work as it constrains the guaranteed domain of the controller. This manuscript ends with a discussion that offers a way to extend the results towards nonlinear models. The idea is to linearize the large-scale nonlinear model around several operating points and interpolate between these points to cover a wider workspace.

Soft materials have gained increasing prominence in science and technology over the last few decades. This shift from traditional rigid materials to soft, compliant materials have led to the emergence of a new class of devices which can interact with humans safely, as well as reduce the disparity in mechanical compliance at the interface of soft human tissue and rigid devices.<br><br>One of the largest application of soft materials has been in the field of flexible electronics, especially in wearable sensors. While wearable sensors for physical attributes such as strain, temperature, etc. have been popular, they lack applications and significance from a healthcare perspective. Point-of-care (POC) devices, on the other hand, provide exceptional healthcare value, bringing useful diagnostic tests to the bedside of the patient. POC devices, however, have been developed for only a limited number of health attributes. In this dissertation I propose and demonstrate wireless, wearable POC devices to measure and communicate the level of various analytes in and the properties of multiple biofluids: blood, urine, wound exudate, and sweat.<br><br>Along with sensors, another prominent area of soft materials application has been in actuators and robots which mimic biological systems not only in their action but also in their soft structure and actuation mechanisms. In this dissertation I develop design strategies to improve upon current soft robots by programming the storage of elastic strain energy. This strategy enables us to fabricate soft actuators capable of programmable and low energy consuming, yet high speed motion. Collectively, this dissertation demonstrates the use of soft compliant materials as the foundation for developing new sensors and actuators for human use and interaction.

<p>Soft pneumatic actuators allow compliant force application and movement for a variety of tasks. While most soft actuators have compliance in directions perpendicular to their direction of force application, they are most often analyzed only in their direction of actuation. In this work, we show a characterization of a soft 3D printed bellows actuator that considers shear and axial deformations, modeling both active and passive degrees of freedom. We build a model based on actuator geometry and a parallel linear and torsional spring system which we fit to experimental data in order to obtain the model constants. We demonstrate this model on two complex parallel networks, a delta mechanism and a floating actuator mechanism, and show how this single actuator model can be used to better predict movements in parallel structures of actuators. These results verify that the presented model and modeling approach can be used to speed up the design and simulation of more complex soft robot models by characterizing both active and passive forces of their one degree-of-freedom soft actuators.<br> </p>

No description available.

Quadruped robots offer distinct advantages in navigating challenging terrains due to their flexible and shock-absorbing characteristics. This flexibility allows them to adapt to uneven surfaces, enhancing their maneuverability. In contrast, rigid robots excel in tasks that require speed and precision but are limited in their ability to navigate complex terrains due to their restricted motion range. Another category of robots, known as soft robots, has gained attention for their unique attributes. Soft robots are characterized by their lightweight and cost-effective design, making them appealing for various applications. Recent advancements have made significant strides in practical control strategies for soft quadruped robots, particularly in diverse and unpredictable environments. An emerging approach in enhancing the autonomy of robots is through reinforcement learning. While this approach shows promise in enabling robots to learn and adapt to their surroundings, it necessitates rigorous training and must exhibit robustness in real-world scenarios. Moreover, a significant hurdle lies in bridging the gap between simulations and reality, as models trained in idealized virtual environments often struggle to perform as expected when deployed in the physical world. This thesis aims to address these challenges by optimizing the control of soft quadruped robots using a model-based reinforcement learning approach. The primary goal is to refine the gait control of these robots, taking into account the complexities encountered in real-world environments. The report covers the implementation of model-based reinforcement learning, including simulation setup, reward design, and policy refinement. Results show improved training efficiency and autonomous behavior, confirming the method’s effectiveness in enhancing soft quadruped robot capabilities.It is important to note that this report provides a concise summary of the thesis results due to the word limit imposed by the Department of Machine Design. For a comprehensive understanding of the research and its implications, the complete version is attached separately here. / Fyrbenta robotar är tack vare deras flexibla och stötdämpande egenskaper är väl lämpade att navigera utmanande terräng. Deras struktur möjliggör anpassning till ojämnheter i underlaget och bidrar till att öka deras rörelseförmåga. I kontrast utmärker sig stela robotar som det bästa valet för uppgifter som kräver snabbhet och precision, men deras förmåga att navigera komplex terräng är begränsad av deras rörelseomfång. En annan typ av robot, så kallade mjuka robotar, har nyligen uppmärksammats för sina unika egenskaper. Dessa robotar kännetecknas av en kostnadseffektiv lättviktsdesign, vilket gör dem attraktiva för många olika användningsområden. Nyligen har betydelsefulla framsteg gjorts inom kontroll av mjuka fyrbenta robotar, framför allt vad gäller kontroll i varierade miljöer. En av de huvudsakliga utmaningarna för att öka robotars autonomi är förstärkningsinlärning. Även om denna teknik är lovande för att ge robotar förmågan att lära sig och anpassa sig efter sin omgivning, kräver den omfattande träning samt måste uppvisa robusthet i verkliga scenarion. Ett större hinder är dessutom klyftan mellan simulation och verklighet, då modeller som tränats i ideella simuleringar ofta presterar sämre än väntat i den fysiska världen. Detta examensarbete behandlar dessa utmaningar genom att implementera en modellbaserad förstärkningsinlärningsmetod för kontroll av fyrbenta robotar, med det primära målet att förfina gångkontrollen för dessa robotar med hänsyn till de komplexa beteenden som uppstår i verkliga miljöer. Denna rapport behandlar implementeringen av modellbaserad förstärkningsin lärning samt simulering, belöningsdesign och policyförfining. Resultat visar på en förbättrad inlärningsförmåga och bättre autonomt beteende, vilket gör metoden lämplig för att förbättra prestandan av mjuka fyrbenta robotar. Var god att notera att denna rapport endast ger en nedkortad sammanfattning av forskningen och dess resultat på grund av krav från institutionen för maskinkonstruktion. En fullständig version innehållande mer detaljer kring studien och dess konsekvenser bifogas här.

<p>Soft robotics is concerned with the modeling and designing of devices fabricated from materials with low Young’s moduli—much less than that of metal— that mimic the input/output operation and physical task utility of robotics.  The inherent compliance of soft robots lends these devices an adaptability and a capacity for human-machine interaction beyond that of conventional robotics. Multistable soft robotic grippers are a subset of the technology at the intersection of soft robotics and multistable structures. Multistable structures are continuum systems that exhibit more than one statically stable state, each associated with a strain energy minimum. The existence of these energetic minima allows the structures to adopt different stable configurations that can provide a reference point for open loop control schemes. Multistable soft robotics takes advantage of both the adaptability of soft robotics and the potential for simplified control of multistable structures.</p> <p>Achieving simplified control for soft robotics is a necessary milestone in creating functional and applied soft robots. </p> <p>This work presents a means for simple open-loop control of a multistable soft robotic gripper that is adaptable, controllable, and robust. The behavior is illustrated through a gripper geometry described by specific design parameters resulting in a near infinite design space. An analytical model based on lumped parameter springs is derived, allowing us to search the design space in a tractable fashion. Specifically, we predict the system’s stable states for any given design instance by searching for local minima in the energy landscape formed by a spring lattice representation of our device. The lattice is composed of linear, bistable, and torsional springs—each of which contributes to the energy landscape of the system. We validate our model against Finite Element simulations of our device, showing good agreement with the proposed model. The aptitude of the model sheds light on the fundamental mechanics of our soft robotic gripper topology, laying the foundation for efficient design optimization and simplified control of soft robots.</p>

Quadrupedal robots are mobile robots with four limbs. Compared with other mobile robots, quadrupedal robots are more capable of moving in complex environment. Specifically, softquadrupedal robots have the limbs that are flexible and more compliant with the environmentthan that of rigid quadrupedal robots. This project is based on a previous work at KTH where a soft quadrupedal robot prototype was built. The first part of this project is to build a test rig, analyze the dynamics of the 3D printed soft continuum actuators and choose one configuration toachieve the best dynamics. The second part of this project is to build a soft quadrupedal robotand analyze the standing and walking performance. The mechanical and electrical structure ofthe robot are re-designed to reduce the weight. Furthermore, gait analyses are conducted toenable the robot to walk. Cost of transport is calculated to compare the efficiency of differentgaits. / Mobila robotar som har fyra lemmar kallas fyrbenta robotar. Jämfört med andra mobila robotarär fyrbenta robotar mer kapabla att röra sig i komplexa miljöer. Särskild de mjuka fyrbentarobotar, vars flexibla lemmar är mer kompatibla med miljön än dem av stela fyrbenta robotar. Det här projektet är baserat på ett tidigare arbete på KTH där prototypen av en mjuk fyrbentrobot byggdes. Den första delen av detta projekt är att bygga en provrigg, analysera dynamikenav det 3D-skrivna mjuka kontinuumställdon och välja den konfigurationen som har bästadynamiken. Den andra delen av detta projekt är att bygga en mjuk fyrbent robot och analyseradess stå- och gångprestation. Den mekaniska och elektriska strukturen av roboten designades omför att minska vikten. Vidare är gångs analyser genomförda för att möjliggöra robotens gång. Cost of transport (COT) är uträknat för att jämföra olika gångs effektivitet.

Work-related musculoskeletal disorders (WMSDs) due to overexertion and consequently the low back pain (LBP) are one of the most prevalent sources of nonfatal occupational injuries and illnesses in all over the world. In the past several years, the industrial exoskeletons especially the passive ones have been proposed as alternative intervention and assistive devices, which are capable of reducing the risk of WMSDs and LBP. However, more research is warranted to validate the applicability of these exoskeletons. In addition, because the majority of previous studies have been limited to specific lifting tasks using only one type of lift assistive exoskeleton, more research is needed to examine the effect of alteration of different lift-assistive exoskeletons on reducing the activity of back muscles and metabolic reduction. The main objective of this dissertation is to render an overview of three studies that attempt to improve the literature by providing comprehensive biomechanical evaluations and metabolic assessments of three passive lift-assistive exoskeletons (VT-Lowe's Exoskeleton (developed in ARLab at VT), Laevo and SuitX). This dissertation has been composed of three related studies. The first study aimed to investigate and examine the capability of a novel lift assistive exoskeleton, VT-Lowe's exoskeleton, in reducing the peak and mean activity of back and leg muscles. Findings revealed that the exoskeleton significantly decreased the peak and mean activity of back muscles (IL(iliocostalis lumborum) and LT(longissimus thoracis)) by 31.5% and 29.3% respectively for symmetric lifts, and by 28.2% and 29.5% respectively for asymmetric lifts. Furthermore, the peak and mean EMG of leg muscles were significantly reduced by 19.1% and 14.1% during symmetric lifts, and 17.4% and 14.6% during asymmetric lifts. Interestingly, the VT-Lowe's exoskeleton showed higher reduction in activity of back and leg muscles compared to other passive lift-assistive exoskeletons available in the literatures. In the second study, the metabolic cost reduction associated with the use of VT-Lowe's exoskeleton during freestyle lifting was theoretically modelled, validated and corresponding metabolic savings were reported. The metabolic cost and the oxygen consumption results supported the hypothesis that the VT-Lowe's exoskeleton could significantly reduce the metabolic demands (~7.9% on average) and oxygen uptake (~8.7% on average) during freestyle lifting. Additionally, we presented a prediction model for the metabolic cost of exoskeleton during repetitive freestyle lifting tasks. The prediction models were very accurate as the absolute prediction errors were small for both 0% (< 1.4%) and 20% (< 0.7%) of body weight. In the third study, the biomechanical evaluation, energy expenditure and subjective assessments of two passive back-support exoskeletons (Laevo and SuitX) were examined in the context of repetitive lifting tasks. The experimental lifting tasks in this study were simulated in a laboratory environment for two different levels of lifting symmetry (symmetric vs. asymmetric) and lifting posture (standing vs. kneeling). Results of this study demonstrated that using both exoskeletons during dynamic lifting tasks could significantly lower the peak activity of trunk extensor muscles by ~10-28%. In addition, using both exoskeletons could save the energy expenditure by ~4-13% in all conditions tested by partially offsetting the weight of the torso. Such reductions were, though, task-dependent and differed between the two tested exoskeletons. Overall, the results of all three studies in this dissertation showed the capability of passive lift-assistive exoskeletons in reducing the activity of back and leg muscles and providing metabolic savings during repetitive lifting tasks. / Doctor of Philosophy / Low back pain (LBP) due to overexertion is known as one of the most important sources of nonfatal occupational injuries especially for the workers or manual material handlers who are involved in frequent or repetitive lifting tasks. Every year, many workers are temporarily or permanently disabled due to overuse injuries at workplace. In the past several years, industrial exoskeletons have gained growing interest among biomechanist, roboticist, and other human factor researchers as potential assistive devices to reduce the risk of LBP. In general, the industrial exoskeletons are either “passive or “active”; Active exoskeletons are powered by mechanical/electrical motors and actuators, however, the passive exoskeletons often work using cheaper devices such as gas or metal springs, elastic elements, etc. The exoskeletons discussed in this dissertation are categorized as passive rigid lower-back exoskeletons and they function by storing energy in a spring when the wearer bends and returning the stored energy when the wearer lifts. This dissertation consists of three studies that attempt to provide comprehensive biomechanical evaluations and metabolic assessments of three passive lift-assistive exoskeletons (i.e., VT-Lowe’s Exoskeleton, Laevo and SuitX). The first study examined the efficacy of a novel lift-assistive exoskeleton, VT-Lowe’s exoskeleton, in reducing the peak and mean activity of back and leg muscles. The results of this study demonstrated that the exoskeleton reduced the peak and mean activity of back and leg muscles for symmetric and asymmetric lifting tasks. VT-Lowe’s exoskeleton also showed higher reduction in activity of back muscles compared to other passive lift-assistive exoskeletons available in the literature. In the second study, the metabolic cost reduction with VT-Lowe’s exoskeleton was theoretically modeled and the modeling outcomes were compared to metabolic costs measurements when the exoskeleton was worn. The experimental findings of this study supported the applicability of the exoskeleton by significantly reducing the metabolic cost and oxygen uptake during the freestyle repetitive lifting tasks. Moreover, the prediction metabolic cost model of the exoskeleton showed high accuracy as the absolute prediction errors were within 1.5%. In the third study, the biomechanical evaluation, energy expenditure and subjective assessments of two passive back-support exoskeletons (Laevo and SuitX) were examined in repetitive lifting tasks. The lifting tasks of this study were simulated in a laboratory environment for two different levels of lifting symmetry (symmetric vs. asymmetric) and lifting posture (standing vs. kneeling). Findings of this study showed that both exoskeleton significantly lowered the peak activity of back muscles during the dynamic lifting tasks. Moreover, using both exoskeletons provided metabolic cost savings in all of the studies conditions. Overall, results obtained from the three studies in this dissertation verified the capability of these passive lift- vi assistive exoskeleton in reducing the activity of back and leg muscles and providing the metabolic savings during repetitive lifting tasks.

Le sujet principal de cette thèse est le développement d’un contrôle commande intelligentpour une prothèse de main robotique avec des parties souples qui comporte: (i) uneinterface homme–machine permettant de contrôler notre prothèse, (ii) et des stratégiesde contrôle améliorant les performances de la main robotique. Notre approche tientcompte : 1. du développement d’une interaction intuitive entre l'homme et la prothèse facilitantl'utilisation de la main, d'un système d’interaction entre l’utilisateur et la mainreposant sur l'acquisition de signaux ElectroMyoGrammes superficiels (sEMG) aumoyen d'un dispositif placé sur l'avant-bras du patient. Les signaux obtenus sontensuite traités avec un algorithme basé sur l'intelligence artificielle, en vued'identifier automatiquement les mouvements désirés par le patient.2. du contrôle de la main robotique grâce à la détection du contact avec l’objet et de lathéorie du contrôle hybride.Ainsi, nous concentrons notre étude sur : (i) l’établissement d’une relation entre lemouvement du membre supérieur et les signaux sEMG, (ii) les séparateurs à vaste margepour classer les patterns obtenues à partir des signaux sEMG correspondant auxmouvements de préhension, (iii) le développement d'un système de reconnaissance depréhension à partir d'un dispositif portable MyoArmbandTM, (iv) et des stratégieshybrides de contrôle commande de force-position de notre main robotique souple. / The target of this thesis disertation is to develop a new Smart control of a soft robotic hand prosthesis for the soft robotic hand prosthesis called ProMain Hand, which is characterized by:(i) flexible interaction with grasped object, (ii) and friendly-intuitive interaction between human and robot hand. Flexible interaction results from the synergies between rigid bodies and soft bodies, and actuation mechanism. The ProMain hand has three fingers, each one is equipped with three phalanges: proximal, medial and distal. The proximal and medial are built with rigid bodies,and the distal is fabricated using a deformable material. The soft distal phalange has a new smart force sensor, which was created with the aim to detect contact and force in the fingertip, facilitating the control of the hand. The friendly intuitive human-hand interaction is developed to facilitate the hand utilization. The human-hand interaction is driven by a controller that uses the superficial electromyographic signals measured in the forearm employing a wearable device. The wearable device called MyoArmband is placed around the forearm near the elbow joint. Based on the signals transmitted by the wearable device, the beginning of the movement is automatically detected, analyzing entropy behavior of the EMG signals through artificial intelligence. Then, three selected grasping gesture are recognized with the following methodology: (i) learning patients entropy patterns from electromyographic signals captured during the execution of selected grasping gesture, (ii) performing a support vector machine classifier, using raw entropy data extracted in real time from electromyographic signals.