The Development of a Sensitive Manipulation End Effector

This thesis designed and realized a two-degree of freedom wrist and two finger manipulator that completes the six-degree of freedom Sensitive Manipulation Platform, the arm of which was previously developed. This platform extends the previous research in the field of robotics by covering not only the end effector with deformable tactile sensors, but also the links of the arm. Having tactile sensors on the arm will improve the dynamic model of the system during contact with its environment and will allow research in contact navigation to be explored. This type of research is intended for developing algorithms for exploring dynamic environments. Unlike traditional robots that focus on collision avoidance, this platform is designed to seek out contact and use it to gather important information about its surroundings. This small desktop platform was designed to have similar proportions and properties to a small human arm. These properties include compliant joints and tactile sensitivity along the lengths of the arms. The primary applications for the completed platform will be research in contact navigation and manipulation in dynamic environments. However, there are countless potential applications for a compliant arm with increased tactile feedback, including prosthetics and domestic robotics. This thesis covers the details behind the design, analysis, and evaluation of the two degrees of the Wrist and two two-link fingers, with particular attention being given to the integration of series elastics actuators, the decoupling of the fingers from the wrist, and the incorporation of tactile sensors in both the forearm motor module and fingers

Development and Biomechanical Analysis toward a Mechanically Passive Wearable Shoulder Exoskeleton

Shoulder disability is a prevalent health issue associated with various orthopedic and neurological conditions, like rotator cuff tear and peripheral nerve injury. Many individuals with shoulder disability experience mild to moderate impairment and struggle with elevating the shoulder or holding the arm against gravity. To address this clinical need, I have focused my research on developing wearable passive exoskeletons that provide continuous at-home movement assistance. Through a combination of experiments and computational tools, I aim to optimize the design of these exoskeletons. In pursuit of this goal, I have designed, fabricated, and preliminarily evaluated a wearable, passive, cam-driven shoulder exoskeleton prototype. Notably, the exoskeleton features a modular spring-cam-wheel module, allowing customizable assistive force to compensate for different proportions of the shoulder elevation moment due to gravity. The results of my research demonstrated that this exoskeleton, providing modest one-fourth gravity moment compensation at the shoulder, can effectively reduce muscle activity, including deltoid and rotator cuff muscles. One crucial aspect of passive shoulder exoskeleton design is determining the optimal anti-gravity assistance level. I have addressed this challenge using computational tools and found that an assistance level within the range of 20-30% of the maximum gravity torque at the shoulder joint yields superior performance for specific shoulder functional tasks. When facing a new task dynamic, such as wearing a passive shoulder exoskeleton, the human neuro-musculoskeletal system adapts and modulates limb impedance at the end-limb (i.e., hand) to enhance task stability. I have presented development and validation of a realistic neuromusculoskeletal model of the upper limb that can predict stiffness modulation and motor adaptation in response to newly introduced environments and force fields. Future studies will explore the model\u27s applicability in predicting stiffness modulation for 3D movements in novel environments, such as passive assistive devices\u27 force fields

Kinematics and statics of cable-driven parallel robots by interval-analysis-based methods

In the past two decades the work of a growing portion of researchers in robotics focused on a particular group of machines, belonging to the family of parallel manipulators: the cable robots. Although these robots share several theoretical elements with the better known parallel robots, they still present completely (or partly) unsolved issues. In particular, the study of their kinematic, already a difficult subject for conventional parallel manipulators, is further complicated by the non-linear nature of cables, which can exert only efforts of pure traction. The work presented in this thesis therefore focuses on the study of the kinematics of these robots and on the development of numerical techniques able to address some of the problems related to it. Most of the work is focused on the development of an interval-analysis based procedure for the solution of the direct geometric problem of a generic cable manipulator. This technique, as well as allowing for a rapid solution of the problem, also guarantees the results obtained against rounding and elimination errors and can take into account any uncertainties in the model of the problem. The developed code has been tested with the help of a small manipulator whose realization is described in this dissertation together with the auxiliary work done during its design and simulation phases.Negli ultimi decenni il lavoro di una parte sempre maggiore di ricercatori che si occupano di robotica si è concentrato su un particolare gruppo di robot appartenenti alla famiglia dei manipolatori paralleli: i robot a cavi. Nonostante i numerosi studi al riguardo, questi robot presentano ancora oggi numerose problematiche del tutto (o in parte) irrisolte. Lo studio della loro cinematica nello specifico, già complesso per i manipolatori paralleli tradizionali, è ulteriormente complicato dalla natura non lineare dei cavi, i quali possono esercitare sforzi di sola trazione. Il lavoro presentato in questa tesi si concentra dunque sullo studio della cinematica dei robot a cavi e sulla messa a punto di tecniche numeriche in grado di affrontare parte delle problematiche ad essa legate. La maggior parte del lavoro è incentrata sullo sviluppo di una procedura per la soluzione del problema geometrico diretto di un generico manipolatore a cavi basata sull'analisi per intervalli. Questa tecnica di analisi numeirica, oltre a consentire una rapida soluzione del problema, permette di garantire i risultati ottenuti in caso di errori di cancellazione e arrotondamento e consente di considerare eventuali incertezze presenti nel modello del problema. Il codice sviluppato è stato testato attraverso un piccolo prototipo di manipolatore a cavi la cui realizzazione, avvenuta durante il percorso di dottrato, è descritta all'interno dell'elaborato unitamente al lavoro collaterale svolto durante la fase di progettazione e simulazione.Pendant les dernières décennies, le travail d'une partie toujours croissante de chercheurs qui s'occupent de robotique s'est focalisé sur un groupe spécifique de robots qui fait partie de la famille des manipulateurs parallèles: les robots à câbles. Malgré les nombreux études que l'on a consacré à ce sujet, ces robots présentent encore aujourd'hui plusieurs problématiques complètement ou partiellement irrésolues. En particulier l'étude de leur cinématique, qui se révèle déjà complexe pour les manipulateurs parallèles traditionnels, est rendu encore plus compliqué par la nature non linéaire des câbles qui peuvent seulement exercer des efforts de traction. Le travail présenté dans ma thèse concentre donc son attention sur l'étude de la cinématique des robots à câbles et sur la mise au point de techniques numériques capables d'aborder une partie des problématiques liées à cela. La plupart du travail se concentre sur l'élaboration d'un algorithme pour la résolution du problème géométrique direct d'un manipulateur à câbles général qui se fonde sur l'analyse par intervalles. Cette technique d'analyse permet non seulement de résoudre rapidement le problème mais également de garantir les résultats obtenus en cas d'erreur de cancellation et d'arrondi et de prendre en considération les incertitudes éventuellement presentes dans le modèle du problème. Le code développé a été testé grâce à un petit prototype de manipulateur à câbles dont la réalisation, qui a eu lieu pendant le parcours de doctorat, est décrite à l'intérieur du devoir en accord avec la phase de conception du projet et de simulation

FEM-based Reachable Workspace Estimation of Soft Robots using an Interval Analysis approach

International audienceConsidering a soft robot with installed bounded actuators, this paper studies the reachable workspace estimation problem for a pre-chosen point of interest. To this aim, the method of nite-element has been used to obtain the static model of the studied robot and two methods are proposed (forward one which is based on Newton iterative method and forward-backward one which is based on interval analysis techniques) to study this estimation problem. Various simulations with dierent conguration scenarios are provided to show the eectiveness of the forward-backward approach which can largely reduce the exploration time, compared to the forward method

Computational Modeling and Experimental Characterization of Pneumatically Driven Actuators for the Development of a Soft Robotic Arm

abstract: Soft Poly-Limb (SPL) is a pneumatically driven, wearable, soft continuum robotic arm designed to aid humans with medical conditions, such as cerebral palsy, paraplegia, cervical spondylotic myelopathy, perform activities of daily living. To support user's tasks, the SPL acts as an additional limb extending from the human body which can be controlled to perform safe and compliant mobile manipulation in three-dimensional space. The SPL is inspired by invertebrate limbs, such as the elephant trunk and the arms of the octopus. In this work, various geometrical and physical parameters of the SPL are identified, and behavior of the actuators that comprise it are studied by varying their parameters through novel quasi-static computational models. As a result, this study provides a set of engineering design rules to create soft actuators for continuum soft robotic arms by understanding how varying parameters affect the actuator's motion as a function of the input pressure. A prototype of the SPL is fabricated to analyze the accuracy of these computational models by performing linear expansion, bending and arbitrary pose tests. Furthermore, combinations of the parameters based on the application of the SPL are determined to affect the weight, payload capacity, and stiffness of the arm. Experimental results demonstrate the accuracy of the proposed computational models and help in understanding the behavior of soft compliant actuators. Finally, based on the set functional requirements for the assistance of impaired users, results show the effectiveness of the SPL in performing tasks for activities of daily living.Dissertation/ThesisMasters Thesis Mechanical Engineering 201

Pressure-Constrained, Reduced-DOF, Interconnected Parallel Manipulators with Applications to Space Suit Design

This dissertation presents the concept of a Morphing Upper Torso, an innovative pressure suit design that incorporates robotic elements to enable a resizable, highly mobile and easy to don/doff spacesuit. The torso is modeled as a system of interconnected, pressure-constrained, reduced-DOF, wire-actuated parallel manipulators, that enable the dimensions of the suit to be reconfigured to match the wearer. The kinematics, dynamics and control of wire-actuated manipulators are derived and simulated, along with the Jacobian transforms, which relate the total twist vector of the system to the vector of actuator velocities. Tools are developed that allow calculation of the workspace for both single and interconnected reduced-DOF robots of this type, using knowledge of the link lengths. The forward kinematics and statics equations are combined and solved to produce the pose of the platforms along with the link tensions. These tools allow analysis of the full Morphing Upper Torso design, in which the back hatch of a rear-entry torso is interconnected with the waist ring, helmet ring and two scye bearings. Half-scale and full-scale experimental models are used along with analytical models to examine the feasibility of this novel space suit concept. The analytical and experimental results demonstrate that the torso could be expanded to facilitate donning and doffing, and then contracted to match different wearer's body dimensions. Using the system of interconnected parallel manipulators, suit components can be accurately repositioned to different desired configurations. The demonstrated feasibility of the Morphing Upper Torso concept makes it an exciting candidate for inclusion in a future planetary suit architecture

Parallel Manipulators

In recent years, parallel kinematics mechanisms have attracted a lot of attention from the academic and industrial communities due to potential applications not only as robot manipulators but also as machine tools. Generally, the criteria used to compare the performance of traditional serial robots and parallel robots are the workspace, the ratio between the payload and the robot mass, accuracy, and dynamic behaviour. In addition to the reduced coupling effect between joints, parallel robots bring the benefits of much higher payload-robot mass ratios, superior accuracy and greater stiffness; qualities which lead to better dynamic performance. The main drawback with parallel robots is the relatively small workspace. A great deal of research on parallel robots has been carried out worldwide, and a large number of parallel mechanism systems have been built for various applications, such as remote handling, machine tools, medical robots, simulators, micro-robots, and humanoid robots. This book opens a window to exceptional research and development work on parallel mechanisms contributed by authors from around the world. Through this window the reader can get a good view of current parallel robot research and applications