Development of a twisted-string actuator for a cable-driven haptic interface

Il seguente lavoro di tesi ha avuto lo scopo di analizzare dal punto di vista della progettazione software le procedure ed i protocolli di scambio di informazioni tra i vari componenti di una nuova concezione di Interfaccia Aptica guidata da 4 tendini che muovono un braccialetto centrale collegato al braccio di un operatore così da fornirgli un feedback di forza. In particolare ci si è focalizzati sullo sviluppo di un firmware applicabile ai 4 motori che muovono la struttura centrale della interfaccia. Il firmware deve essere in grado di ricevere da una piattaforma Ros, usata da un operatore, pacchetti di dati contenenti i set point per i vari motori e il tipo di controllo , posizione o forza, che gli attuatori devono effettuare grazie ad uno schema PID. Inoltre l'invio di feedback all'operatore è stato previsto in modo da permettere una maggiore supervisione dell'intero funzionamento. La realizzazione di un Ros Bridge tra l'utente e il sistema da comandare è stato implementato con la formula della programmazione ad oggetti in cui varie classi sono dedicate a compiti differenti come l'impacchettamento di dati da mandare ai motori e la contemporanea ricezione dei feedback. Per completare tutta l'architettura si è anche sviluppato un sistema di trasformazione dei set point provenienti dall'operatore espressi nello spazio di lavoro Cartesiano in riferimenti per i singoli motori e ciò è stato possibile sfruttando la matrice Jacobiana. Una particolare attenzione è stata data all'aspetto di comunicazione dei dati e per fare ciò si è dovuta usare una architettura di codice a multithread e un protocollo UDP

Design and Implementation of Innovative Robotic Devices Using Twisted String Actuation (TSA) System

The twisted string actuation system is particularly suitable for very compact, low-cost and light-weight robotic devices, like artificial limbs and exoskeletons, since it allows the implementation of powerful tendon-based driving systems, based on small-size DC motors characterized by high speed, low torque and very limited inertia. The following activities has been done using the Twisted String Actuation System: - The basic properties of the twisted string actuation system. - An ongoing work for verifying the behavior of a twisted string actuator in contact with a sliding surface or guided through a sheath. - The implementation of a variable stiffness joint actuated by a couple of twisted string actuators in antagonistic configuration. - The design and the implementation of a force sensor based on a commercial optoelectronic component called light fork and characterized by the simple construction process. - A twisted string actuation module with an integrated force sensor based on optoelectronic components. - The preliminary experimental study toward the implementation of an arm rehabilitation device based on a twisted string actuation module. - A 6 DoF cable-driven haptic interface for applications in various robotic scenarios. - A wearable hand haptic interface driven by a couple of twisted string actuators

Design Criteria of Soft Exogloves for Hand Rehabilitation- Assistance Tasks

This paper establishes design criteria for soft exogloves (SEG) to be used as rehabilitation or assistance devices. This research consists in identifying, selecting, and grouping SEG features based on the analysis of 91 systems that have been proposed during the last decade. Thus, function, mobility, and usability criteria are defined and explicitly discussed to highlight SEG design guidelines. Additionally, this study provides a detailed description of each system that was analysed including application, functional task, palm design, actuation type, assistance mode, degrees of freedom (DOF), target fingers, motions, material, weight, force, pressure (only for fluids), control strategy, and assessment. Such characteristics have been reported according to specific design methodologies and operating principles. Technological trends are contemplated in this contribution with emphasis on SEG design opportunity areas. In this review, suggestions, limitations, and implications are also discussed in order to enhance future SEG developments aimed at stroke survivors or people with hand disabilities

Hands: Human to Robotic

Hands have for centuries been recognized as a fundamental tool for humans to gain an understanding of their environment and at the same time be able to manipulate it. In this presentation we will look at various studies made on the functionality and use of the human hand and examine the different approaches to analyzing and classifying human grasps and building a taxonomy of these grasps. We study the anatomy of the human hand, and examine experiments performed to understand the how gripping forces are applied when lifting objects, and the methods extraction of haptic information, by humans. We discuss issues involved in the building of electro-mechanical manipulators and some of the mathematics used in analyzing the suitability of a design. We look at one of the earliest designs of a computer controlled articulated gripper, as well as two of the most prevalent designs in today\u27s research world, the Stanford/JPL hand and the Utah/MIT had. Finally, we show why a more fundamental understanding of how human grasping works will help us design more useful manipulators

Modeling, Analysis, Force Sensing and Control of Continuum Robots for Minimally Invasive Surgery

This dissertation describes design, modeling and application of continuum robotics for surgical applications, specifically parallel continuum robots (PCRs) and concentric tube manipulators (CTMs). The introduction of robotics into surgical applications has allowed for a greater degree of precision, less invasive access to more remote surgical sites, and user-intuitive interfaces with enhanced vision systems. The most recent developments have been in the space of continuum robots, whose exible structure create an inherent safety factor when in contact with fragile tissues. The design challenges that exist involve balancing size and strength of the manipulators, controlling the manipulators over long transmission pathways, and incorporating force sensing and feedback from the manipulators to the user. Contributions presented in this work include: (1) prototyping, design, force sensing, and force control investigations of PCRs, and (2) prototyping of a concentric tube manipulator for use in a standard colonoscope. A general kinetostatic model is presented for PCRs along with identification of multiple physical constraints encountered in design and construction. Design considerations and manipulator capabilities are examined in the form of matrix metrics and ellipsoid representations. Finally, force sensing and control are explored and experimental results are provided showing the accuracy of force estimates based on actuation force measurements and control capabilities. An overview of the design requirements, manipulator construction, analysis and experimental results are provided for a CTM used as a tool manipulator in a traditional colonoscope. Currently, tools used in colonoscopic procedures are straight and exit the front of the scope with 1 DOF of operation (jaws of a grasper, tightening of a loop, etc.). This research shows that with a CTM deployed, the dexterity of these tools can be increased dramatically, increasing accuracy of tool operation, ease of use and safety of the overall procedure. The prototype investigated in this work allows for multiple tools to be used during a single procedure. Experimental results show the feasibility and advantages of the newly-designed manipulators

ARCTiC LawE: armed robotic control for training in civilian law enforcement

Much of this thesis looked at performing a cogent literature review of exoskeletons to determine the state-of-the-art and to determine the remaining needs in exoskeletal design. The literature review of over 80 journals, allowed the researcher to determine the lack of research in upper body exoskeletons for training in civilian, military, and law enforcement personnel. Thus the genesis of the Armed Robotic Control for Training in Civilian Law Enforcement, or ARCTiC LawE, an upper body exoskeleton designed to assist civilian, military, and law enforcement personnel in accurate, precise, and reliable handgun techniques. This exoskeleton training utilizes a laser based handgun with similar dimensions, trigger pull, and break action to a Glock ® 19 pistol, common to both public and private security sectors. The project aims to train and test subjects with no handgun training/experience with the ARCTiC LawE, and without, and compare the results of accuracy, precision, and speed. Ultimately, the exoskeleton greatly impacts sensory motor learning and the biomechanical implications are confirmed via both performance and physiological measurements. The researchers believe the ARCTiC LawE to be a viable substitute for training with live fire hand guns to reduce the cost of training time and munitions and will increase accuracy and precisions for typical law enforcement and military live fire drills. Additionally, this project increases the breadth of knowledge for exoskeletons as a tool for training

Haptics: Science, Technology, Applications

This open access book constitutes the proceedings of the 12th International Conference on Human Haptic Sensing and Touch Enabled Computer Applications, EuroHaptics 2020, held in Leiden, The Netherlands, in September 2020. The 60 papers presented in this volume were carefully reviewed and selected from 111 submissions. The were organized in topical sections on haptic science, haptic technology, and haptic applications. This year's focus is on accessibility

Haptics Rendering and Applications

There has been significant progress in haptic technologies but the incorporation of haptics into virtual environments is still in its infancy. A wide range of the new society's human activities including communication, education, art, entertainment, commerce and science would forever change if we learned how to capture, manipulate and reproduce haptic sensory stimuli that are nearly indistinguishable from reality. For the field to move forward, many commercial and technological barriers need to be overcome. By rendering how objects feel through haptic technology, we communicate information that might reflect a desire to speak a physically- based language that has never been explored before. Due to constant improvement in haptics technology and increasing levels of research into and development of haptics-related algorithms, protocols and devices, there is a belief that haptics technology has a promising future

Mesure tactile proprioceptive pour des doigts sous-actionnés

RÉSUMÉ La préhension et la manipulation d’objets par des robots deviennent de plus en plus répandues dans divers domaines, et ce, pour de multiples applications. L’utilisation de robots permet d’améliorer la répétabilité, la rapidité et la précision lors de certaines tâches, et ce, comparativement aux performances d’un opérateur humain. De plus, un robot peut également être conçu pour accomplir certaines tâches qu’une personne ne pourrait effectuer, que ce soit au niveau de la force nécessaire ou du manque d’espace pour manoeuvrer. Des robots peuvent également plus aisément fonctionner dans des environnements hostiles. Tout comme pour l’être humain, la rétroaction tactile est particulièrement utile et même inévitable pour effectuer certaines tâches. Il faut toutefois souligner qu’il s’agit d’un thème de recherche où l’on est encore bien loin d’avoir atteint les performances humaines. Pour s’en approcher, de nombreuses et diverses technologies de capteurs tactiles existent, mais chacune comporte ses défauts. Ainsi, bien qu’il existe actuellement des solutions technologiques pour donner une rétroaction sensorielle à un robot ou à son opérateur, ces dernières s’avèrent généralement coûteuses, présentent différents défauts au niveau de la sensibilité et ne sont pas toujours adaptées à certaines utilisations. Dans l’optique de trouver une alternative efficace aux technologies conventionnelles de détection et de mesure tactiles, la présente thèse se concentre sur la possibilité d’utiliser la raideur inhérente du mécanisme de transmission d’un doigt sous-actionné. En effet, les doigts et les mains sous-actionnés sont de plus en plus communément utilisés pour leur simplicité propre et leur capacité à saisir et à s’adapter à la forme d’objet de manière purement mécanique sans schéma de commande complexe ou de nombreux actionneurs. Contrairement aux mécanismes pleinement actionnés, les doigts sous-actionnés, communément appelés adaptatifs, comportent des éléments passifs pour contraindre leur mouvement avant le contact, tout en permettant d’obtenir une prise stable sans développer des forces de contact trop élevées initialement. Les doigts sous-actionnés étant généralement dépourvus d’actionneurs à l’intérieur du doigt lui-même, les seuls capteurs déjà présents sont typiquement situés à l’unique actionneur. Toutefois, en analysant et traitant en temps réel les données de ces capteurs internes, également appelés proprioceptifs, il est possible d’extraire une panoplie d’informations sur ce qui se passe au niveau des phalanges. Ce principe est donc utilisé pour obtenir des algorithmes de détection tactile pouvant être utilisés sur différents systèmes, tels qu’une pince compliante et un préhenseurs à membrures.----------ABSTRACT Robotic hands have become more and more prevalent in many fields. They have replaced human operators in many repetitive applications where robots become more precise and efficient. Moreover, robotic graspers can lift heavier loads and accomplish maneuvers a human could not. They can also manipulate objects in hostile environments where it would be dangerous for humans. Therefore, a lot of work has been done in recent years to improve their capabilities such as their speed, dexterity, strength, and versatility. However, current robotic manipulators lack the sensory feedback of their human counterparts. Indeed, haptic and tactile feedbacks are still very limited in current devices, which may be a problem, because tactile sensing is deemed nearly mandatory for a large number of applications. Conventional tactile sensors, which are usually applied on the external surface of a robot, are generally used, but they can also be costly, insensitive to some dynamic phenomena, and not adequate to some applications. To solve these issues, many authors have worked on finding alternatives to standard tactile sensors. This thesis fits in this current trend by focusing on the possibility of using the internal stiffness of underactuated fingers to design a virtual tactile sensor. This technique is referred to as proprioceptive tactile sensing. It is applied here to underactuated robotics fingers, which are becoming prevalent in many fields. Underactuated mechanisms, sometimes referred to as self-adaptive, are particularly interesting because of their intrinsic ability to mechanically adapt themselves to the shape of an object without complex control laws and as low as only one actuator. As they have by definition less actuators, they generally have no sensor in the finger’s mechanism itself. Instead of adding new sensors, it is possible to take advantage of the sensors already present, such as the ones at the actuator. Therefore, in this thesis, only data provided by sensors at the actuator is used. Since a oneto-one relationship exists between the contact location and the instantaneous stiffness of the mechanism, it is possible to compute one from the other. Therefore, with the measurements from sensors at the actuator, it is possible to estimate the point of contact. To this aim, a complete model is proposed and experimental data is provided. Different algorithms were tested successfully on a compliant biocompatible gripper and a 2-DOF linkage-driven finger. Finally, an optimization procedure is presented with the aim of finding the optimal parameters of the transmission mechanism to improve the sensitivity of the virtual tactile sensor. The data presented in this thesis demonstrate the robustness of the proposed proprioceptive tactile sensing (PTS) technique