Wearable Systems for the Hand with High Functionality and Usability for Virtual Reality

Department of Mechanical EngineeringAs an advanced physical human-robot interaction (pHRI), there has been a surge of interest in a haptic device for virtual reality (VR) field. Especially, wearable force feedback devices which can measure the human???s motion and apply the feeling of the object have been actively investigated. It is ideal to measure all motions of the user, and apply the feelings to all body parts, but it requires many sensors and actuators, resulting that bulky and heavy system. Therefore, the wearable system, which focuses on some body parts which are essential for interacting with virtual environments, should be developed by considering the number of sensors and actuators practically. When it comes to the body parts, the hand is important to grasp and manipulate the object, and interact with external environments. In terms of realizing the feeling of the object, the kinesthetic (force feedback) information mainly affect to distinguish the geometry of the object and manipulate the object, rather than tactile information such as pressure, shear, temperature, etc. Consequently, the wearable force feedback systems for the hand have been actively investigated. For realizing the feeling of the object, various stiffness should be generated by the force feedback system. Since the stiffness is the force change along the position change, two main functions of finger motion measurement and force feedback are required. Those functions can be summarized as functionality. Other subjective factors can be summarized as usability. The usability is the ease of use and usefulness, including quantifiable characteristics, such as user task performances, subjective satisfaction, learnability and user; in this study, it was interpreted as design, wearability, ease of use, etc. However, there are few wearable systems for the hand to utilize the applications for virtual reality. The main reason is that the hand has relatively many degrees of freedom (DOFs) and range of motion (ROM), and generate large force compared to its small size; the wearable systems which could measure the finger motion accurately and apply the precise force were large and heavy because many actuators and sensors were required. In other words, the wearable systems that satisfied high functionality were poor in usability. For high usability, many devices by small motors have been developed, but the corresponding functionality were deteriorated. Designing the system that satisfies both functionality and usability seems to be a trade-off problem, but the wearable system for virtual reality can be applied to the real world only when both elements are satisfied. Therefore, the main goal of this dissertation is to develop a system of both high functionality and usability in order to apply to the actual virtual reality field. Especially, this study aims to enhance the usability by proposing new methods for wearability, ease of use, and by using a small motor to reduce the system weight, but maintain the functionality through various mechanical approaches such as cable and linkage driven mechanisms. First, finger motion measurement systems have been investigated because accurate measurement of the finger motion itself has been challenged due to its many degrees of freedom (DOFs) and range of motion (ROM) based on complex anatomical structures. A compact and glove-type system with potentiometers, springs and flexible wires was proposed to calculate the finger joint angle by length change of the cable. For high functionality and usability, the system which could measure three-dimensional finger motion for users of various hand sizes without a calibration process was developed. Second, the wearable force feedback systems, which achieve both finger motion measurement and force control, were developed. A dual-cable system was proposed to combine force feedback structures on the aforementioned finger motion measurement system with cables. A linkage mechanism based wearable system, called as WeHAPTIC (Wearable Haptic Interface of Accurate Position Tracking and Interactive force Control), were developed to overcome the limitations of the previous system. It was designed to directly connect fingertips and the system to allow various users, to easily worn by latchet based one click structure and to calibrate system with only one simple posture. Lastly, WeHAPTIC-Light was exploited to reduce the system weight by changing to small motors. The cable and linkage driven mechanisms were combined to measure the finger motion without any calibration process and permit fast finger motion. Lastly, extensive experiments were performed for performance verification of our system as the haptic device. Not only physical assessment of the system, but also psychophysical evaluation, which is a quantitative evaluation related to human perception ability, were conducted in this dissertation for comprehensive performance evaluation as the haptic interface.clos

A Wearable Control Interface for Tele-operated Robots

Department of Mehcanical EngineeringThis thesis presents a wearable control interface for the intuitive control of tele-operated robots, which aim to overcome the limitations of conventional uni-directional control interfaces. The control interface is composed of a haptic control interface and a tele-operated display system. The haptic control interface can measure user???s motion while providing force feedback. Thus, the user can control a tele-operated robot arm by moving his/her arm in desired configurations while feeling the interaction forces between the robot and the environment. Immersive visual feedback is provided to the user with the tele-operated display system and a predictive display algorithm. An exoskeleton structure was designed as a candidate of the control interface structure considering the workspace and anatomy of the human arm to ensure natural movement. The translational motion of human shoulder joint and the singularity problem of exoskeleton structures were addressed by the tilted and vertically translating shoulder joint. The proposed design was analyzed using forward and inverse kinematics methods. Because the shoulder elevation affects all of the joint angles, the angles were calculated by applying an inverse kinematics method in an iterative manner. The proposed design was tested in experiments with a kinematic prototype. Two force-controllable cable-driven actuation mechanisms were developed for the actuation of haptic control interfaces. The mechanisms were designed to have lightweight and compact structures for high haptic transparency. One mechanism is an asymmetric cable-driven mechanism that can simplify the cable routing structure by replacing a tendon to a linear spring, which act as an antagonistic force source to the other tendon. High performance force control was achieved by a rotary series elastic mechanism and a robust controller, which combine a proportional and differential (PD) controller optimized by a linear quadratic (LQ) method with a disturbance observer (DOB) and a zero phase error tracking (ZPET) feedforward filter. The other actuation mechanism is a series elastic tendon-sheath actuation mechanism. Unlike previously developed tendon-sheath actuation systems, the proposed mechanism can deliver desired force even in multi-DOF systems by modeling and feedforwardly compensating the friction. The pretension change, which can be a significant threat in the safety of tendon-sheath actuation systems, is reduced by adopting series elastic elements on the motor side. Prototypes of the haptic control interfaces were developed with the proposed actuation mechanisms, and tested in the interaction with a virtual environment or a tele-operation experiment. Also, a visual feedback system is developed adopting a head mounted display (HMD) to the control interface. Inspired by a kinematic model of a human head-neck complex, a robot neck-camera system was built to capture the field of view in a desired orientation. To reduce the sickness caused by the time-varying bidirectional communication delay and operation delay of the robot neck, a predictive display algorithm was developed based on the kinematic model of the human and robot neck-camera system, and the geometrical model of a camera. The performance of the developed system was tested by experiments with intentional delays.clos

FASTKIT: A Mobile Cable-Driven Parallel Robot for Logistics

International audienceThe subject of this paper is about the design, modeling, control and performance evaluation of a low cost and versatile robotic solution for logistics. The robot under study, named FASTKIT, is obtained from a combination of mobile robots and a Cable-Driven Parallel Robot (CDPR). FASTKIT addresses an industrial need for fast picking and kitting operations in existing storage facilities while being easy to install, keeping existing infrastructures and covering large areas. The FASTKIT prototype consists of two mobile bases that carry the exit points of the CDPR. The system can navigate autonomously to the area of interest. Once the desired position is attained, the system deploys the CDPR in such a way that its workspace corresponds to the current task specification. The system calculates the required mobile base position from the desired workspace and ensures the controllability of the platform during the deployment. Once the system is successfully deployed, the set of stabilizers are used to ensure the prototype structural stability. Then the prototype gripper is moved accurately by the CDPR at high velocity over a large area by controlling the cable tension

Shared-Control Teleoperation Paradigms on a Soft Growing Robot Manipulator

Semi-autonomous telerobotic systems allow both humans and robots to exploit their strengths, while enabling personalized execution of a task. However, for new soft robots with degrees of freedom dissimilar to those of human operators, it is unknown how the control of a task should be divided between the human and robot. This work presents a set of interaction paradigms between a human and a soft growing robot manipulator, and demonstrates them in both real and simulated scenarios. The robot can grow and retract by eversion and inversion of its tubular body, a property we exploit to implement interaction paradigms. We implemented and tested six different paradigms of human-robot interaction, beginning with full teleoperation and gradually adding automation to various aspects of the task execution. All paradigms were demonstrated by two expert and two naive operators. Results show that humans and the soft robot manipulator can split control along degrees of freedom while acting simultaneously. In the simple pick-and-place task studied in this work, performance improves as the control is gradually given to the robot, because the robot can correct certain human errors. However, human engagement and enjoyment may be maximized when the task is at least partially shared. Finally, when the human operator is assisted by haptic feedback based on soft robot position errors, we observed that the improvement in performance is highly dependent on the expertise of the human operator.Comment: 15 pages, 14 figure

Reconfigurable cable driven parallel mechanism

Due to the fast growth in industry and in order to reduce manufacturing budget, increase the quality of products and increase the accuracy of manufactured products in addition to assure the safety of workers, people relied on mechanisms for such purposes. Recently, cable driven parallel mechanisms (CDPMs) have attracted much attention due to their many advantages over conventional parallel mechanisms, such as the significantly large workspace and the dynamics capacity. In addition, it has lower mass compared to other parallel mechanisms because of its negligible mass cables compared to the rigid links. In many applications it is required that human interact with machines and robots to achieve tasks precisely and accurately. Therefore, a new domain of scientific research has been introduced, that is human robot interaction, where operators can share the same workspace with robots and machines such as cable driven mechanisms. One of the main requirements due to this interaction that robots should respond to human actions in accurate, harmless way. In addition, the trajectory of the end effector is coming now from the operator and it is very essential that the initial trajectory is kept unchanged to perform tasks such assembly, operating or pick and place while avoiding the cables to interfere with each other or collide with the operator. Accordingly, many issues have been raised such as control, vibrations and stability due the contact between human and robot. Also, one of the most important issues is to guarantee collision free space (to avoid collision between cables and operator and to avoid collisions between cables itself). The aim of this research project is to model, design, analysis and implement reconfigurable six degrees of freedom parallel mechanism driven by eight cables. The main contribution of this work will be as follow. First, develop a nonlinear model and solve the forward and inverse kinematics issue of a fully constrained CDPM given that the attachment points on the rails are moving vertically (conventional cable driven mechanisms have fixed attachment points on the rails) while controlling the cable lengths. Second, the new idea of reconfiguration is then used to avoid interference between cables and between cables and operator limbs in real time by moving one cable’s attachment point on the frame to increase the shortest distance between them while keeping the trajectory of the end effector unchanged. Third, the new proposed approach was tested by creating a simulated intended cable-cable and cable-human interference trajectory, hence detecting and avoiding cable-cable and cable-human collision using the proposed real time reconfiguration while maintaining the initial end effector trajectory. Fourth, study the effect of relocating the attachment points on the constant-orientation wrench feasible workspace of the CDPM. En raison de la croissance de la demande de produits personnalisés et de la nécessité de réduire les coûts de fabrication tout en augmentant la qualité des produits et en augmentant la personnalisation des produits fabriqués en plus d'assurer la sécurité des travailleurs, les concepteurs se sont appuyés sur des mécanismes robotiques afin d’atteindre ces objectifs. Récemment, les mécanismes parallèles entraînés par câble (MPEC) ont attiré beaucoup d'attention en raison de leurs nombreux avantages par rapport aux mécanismes parallèles conventionnels, tels que l'espace de travail considérablement grand et la capacité dynamique. De plus, ce mécanisme a une masse plus faible par rapport à d'autres mécanismes parallèles en raison de ses câbles de masse négligeable comparativement aux liens rigides. Dans de nombreuses applications, il est nécessaire que l’humain interagisse avec les machines et les robots pour réaliser des tâches avec précision et rapidité. Par conséquent, un nouveau domaine de recherche scientifique a été introduit, à savoir l'interaction humain-robot, où les opérateurs peuvent partager le même espace de travail avec des robots et des machines telles que les mécanismes entraînés par des câbles. L'une des principales exigences en raison de cette interaction que les robots doivent répondre aux actions humaines d'une manière sécuritaire et collaboratif. En conséquence, de nombreux problèmes ont été soulevés tels que la commande et la stabilité dues au contact physique entre l’humain et le robot. Aussi, l'un des enjeux les plus importants est de garantir un espace sans collision (pour éviter les collisions entre des câbles et un opérateur et éviter les collisions entre les câbles entre eux). Le but de ce projet de recherche est de modéliser, concevoir, analyser et mettre en œuvre un mécanisme parallèle reconfigurable à six degrés de liberté entraîné par huit câbles. La principale contribution de ces travaux de recherche est de développer un modèle non linéaire et résolvez le problème de cinématique direct et inverse d'un CDPM entièrement contraint étant donné que les points d'attache sur les rails se déplacent verticalement (les mécanismes entraînés par des câbles conventionnels ont des points d'attache fixes sur les rails) tout en contrôlant les longueurs des câbles. Dans une deuxième étape, l’idée de la reconfiguration est ensuite utilisée pour éviter les interférences entre les câbles et entre les câbles et les membres d’un opérateur en temps réel en déplaçant un point de fixation du câble sur le cadre pour augmenter la distance la plus courte entre eux tout en gardant la trajectoire de l'effecteur terminal inchangée. Troisièmement, la nouvelle approche proposée a été évaluée et testée en créant une trajectoire d'interférence câble-câble et câble-humain simulée, détectant et évitant ainsi les collisions câble-câble et câble-humain en utilisant la reconfiguration en temps réel proposée tout en conservant la trajectoire effectrice finale. Enfin la dernière étape des travaux de recherche consiste à étudiez l'effet du déplacement des points d'attache sur l'espace de travail réalisable du CDPM

Kinematic/Dynamic Characteristics for Visual and Kinesthetic Virtual Environments

Work was carried out on two topics of principal importance to current progress in virtual environment research at NASA Ames and elsewhere. The first topic was directed at maximizing the temporal dynamic response of visually presented Virtual Environments (VEs) through reorganization and optimization of system hardware and software. The final results of this portion of the work was a VE system in the Advanced Display and Spatial Perception Laboratory at NASA Ames capable of updating at 60 Hz (the maximum hardware refresh rate) with latencies approaching 30 msec. In the course of achieving this system performance, specialized hardware and software tools for measurement of VE latency and analytic models correlating update rate and latency for different system configurations were developed. The second area of activity was the preliminary development and analysis of a novel kinematic architecture for three Degree Of Freedom (DOF) haptic interfaces--devices that provide force feedback for manipulative interaction with virtual and remote environments. An invention disclosure was filed on this work and a patent application is being pursued by NASA Ames. Activities in these two areas are expanded upon below

Design of a Hand Held Minimally Invasive Lung Tumour Localization Device

Lung cancer is the leading type of cancer that causes death. If diagnosed, the treatment of choice is surgical resection of the tumour. Traditionally, a surgeon feels for the presence of a tumour in open thoracic surgery. However, a minimally invasive approach is desired. A major problem presented by the minimally invasive approach is the localization of the tumour. This project describes the design, analysis, and experimental validation of a novel minimally invasive instrument for lung tumour localization. The instrument end effector is a two degree of freedom lung tissue palpator. It allows for optimal tissue palpation to increase useful sensor feedback by ensuring sensor contact, and prevents tissue damage by uniformly distributing pressure on the tissue with an upper bound force. Finite element analysis was used extensively to guide the design process. The mechanism is actuated using high strength tungsten cables attached to controlled motors. Heat treatment experiments were undertaken with stainless steel alloy 440C for use in the design, achieving a device factor of safety of 4. This factor of safety is based on a 20 N force on the end effector — the approximate weight of a human lung. The design was prototyped and validation experiments were carried out to assess its articulation and its load carrying capacity. Up to 10 N of force was applied to the prototype. Issues to resolve in the current design include cable extension effects and the existence of joint inflection. The end effector was also designed to allow the inclusion of ultrasound, tactile, and kinaesthetic sensors. It is hypothesized that a plurality of sensors will increase the likelihood of positive tumour localization. These sensors, combined with the presented mechanical design, form the basis for research in robotics-assisted palpation. A proof of concept control system is presented for automated palpation

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

An Augmented Interaction Strategy For Designing Human-Machine Interfaces For Hydraulic Excavators

Lack of adequate information feedback and work visibility, and fatigue due to repetition have been identified as the major usability gaps in the human-machine interface (HMI) design of modern hydraulic excavators that subject operators to undue mental and physical workload, resulting in poor performance. To address these gaps, this work proposed an innovative interaction strategy, termed “augmented interaction”, for enhancing the usability of the hydraulic excavator. Augmented interaction involves the embodiment of heads-up display and coordinated control schemes into an efficient, effective and safe HMI. Augmented interaction was demonstrated using a framework consisting of three phases: Design, Implementation/Visualization, and Evaluation (D.IV.E). Guided by this framework, two alternative HMI design concepts (Design A: featuring heads-up display and coordinated control; and Design B: featuring heads-up display and joystick controls) in addition to the existing HMI design (Design C: featuring monitor display and joystick controls) were prototyped. A mixed reality seating buck simulator, named the Hydraulic Excavator Augmented Reality Simulator (H.E.A.R.S), was used to implement the designs and simulate a work environment along with a rock excavation task scenario. A usability evaluation was conducted with twenty participants to characterize the impact of the new HMI types using quantitative (task completion time, TCT; and operating error, OER) and qualitative (subjective workload and user preference) metrics. The results indicated that participants had a shorter TCT with Design A. For OER, there was a lower error probability due to collisions (PER1) with Design A, and lower error probability due to misses (PER2)with Design B. The subjective measures showed a lower overall workload and a high preference for Design B. It was concluded that augmented interaction provides a viable solution for enhancing the usability of the HMI of a hydraulic excavator