Haptic Hand Exoskeleton for Precision Grasp Simulation

This paper outlines the design and the development of a novel robotic hand exoskeleton (HE) conceived for haptic interaction in the context of virtual reality (VR) and teleoperation (TO) applications. The device allows exerting controlled forces on fingertips of the index and thumb of the operator. The new exoskeleton features several design solutions adopted with the aim of optimizing force accuracy and resolution. The use of remote centers of motion mechanisms allows achieving a compact and lightweight design. An improved stiffness of the transmission and reduced requirements for the electromechanical actuators are obtained thanks to a novel principle for integrating speed reduction into torque transmission systems. A custom designed force sensor and integrated electronics are employed to further improve performances. The electromechanical design of the device and the experimental characterization are presented

Experimental evaluation of haptic control for human activated command devices

Haptics refers to a widespread area of research that focuses on the interaction between humans and machine interfaces as applied to the sense of touch. A haptic interface is designed to increase the realism of tactile and kinesthetic sensations in applications such as virtual reality, teleoperation, and other scenarios where situational awareness is considered important, if not vital. This paper investigates the use of electric actuators and non-linear algorithms to provide force feedback to an input command device for providing haptics to the human operator. In particular, this work involves the study and implementation of a special case of feedback linearization known as inverse dynamics control and several outer loop impedance control topologies. It also investigates the issues concerned with force sensing and the application of model based controller functions in order to vary the desired inertia and the desired mass matrix. Results of the controllers’ abilities to display any desired impedance and provide the required kinesthetic constraint of virtual environments are shown on two experimental test rigs designed for this purpose.peer-reviewe

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

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

Design, implementation, control, and user evaluations of assiston-arm self-aligning upper-extremity exoskeleton

Physical rehabilitation therapy is indispensable for treating neurological disabilities. The use of robotic devices for rehabilitation holds high promise, since these devices can bear the physical burden of rehabilitation exercises during intense therapy sessions, while therapists are employed as decision makers. Robot-assisted rehabilitation devices are advantageous as they can be applied to patients with all levels of impairment, allow for easy tuning of the duration and intensity of therapies and enable customized, interactive treatment protocols. Moreover, since robotic devices are particularly good at repetitive tasks, rehabilitation robots can decrease the physical burden on therapists and enable a single therapist to supervise multiple patients simultaneously; hence, help to lower cost of therapies. While the intensity and quality of manually delivered therapies depend on the skill and fatigue level of therapists, high-intensity robotic therapies can always be delivered with high accuracy. Thanks to their integrated sensors, robotic devices can gather measurements throughout therapies, enable quantitative tracking of patient progress and development of evidence-based personalized rehabilitation programs. In this dissertation, we present the design, control, characterization and user evaluations of AssistOn-Arm, a powered, self-aligning exoskeleton for robotassisted upper-extremity rehabilitation. AssistOn-Arm is designed as a passive back-driveable impedance-type robot such that patients/therapists can move the device transparently, without much interference of the device dynamics on natural movements. Thanks to its novel kinematics and mechanically transparent design, AssistOn-Arm can passively self-align its joint axes to provide an ideal match between human joint axes and the exoskeleton axes, guaranteeing ergonomic movements and comfort throughout physical therapies. The self-aligning property of AssistOn-Arm not only increases the usable range of motion for robot-assisted upper-extremity exercises to cover almost the whole human arm workspace, but also enables the delivery of glenohumeral mobilization (scapular elevation/depression and protraction/retraction) and scapular stabilization exercises, extending the type of therapies that can be administered using upper-extremity exoskeletons. Furthermore, the self-alignment property of AssistOn-Arm signi cantly shortens the setup time required to attach a patient to the exoskeleton. As an impedance-type device with high passive back-driveability, AssistOn- Arm can be force controlled without the need of force sensors; hence, high delity interaction control performance can be achieved with open-loop impedance control. This control architecture not only simpli es implementation, but also enhances safety (coupled stability robustness), since open-loop force control does not su er from the fundamental bandwidth and stability limitations of force-feedback. Experimental characterizations and user studies with healthy volunteers con- rm the transparency, range of motion, and control performance of AssistOn- Ar

A Haptic Surface Robot Interface for Large-Format Touchscreen Displays

This thesis presents the design for a novel haptic interface for large-format touchscreens. Techniques such as electrovibration, ultrasonic vibration, and external braked devices have been developed by other researchers to deliver haptic feedback to touchscreen users. However, these methods do not address the need for spatial constraints that only restrict user motion in the direction of the constraint. This technology gap contributes to the lack of haptic technology available for touchscreen-based upper-limb rehabilitation, despite the prevalent use of haptics in other forms of robotic rehabilitation. The goal of this thesis is to display kinesthetic haptic constraints to the touchscreen user in the form of boundaries and paths, which assist or challenge the user in interacting with the touchscreen. The presented prototype accomplishes this by steering a single wheel in contact with the display while remaining driven by the user. It employs a novel embedded force sensor, which it uses to measure the interaction force between the user and the touchscreen. The haptic response of the device is controlled using this force data to characterize user intent. The prototype can operate in a simulated free mode as well as simulate rigid and compliant obstacles and path constraints. A data architecture has been created to allow the prototype to be used as a peripheral add-on device which reacts to haptic environments created and modified on the touchscreen. The long-term goal of this work is to create a haptic system that enables a touchscreen-based rehabilitation platform for people with upper limb impairments

Cable-driven parallel mechanisms for minimally invasive robotic surgery

Minimally invasive surgery (MIS) has revolutionised surgery by providing faster recovery times, less post-operative complications, improved cosmesis and reduced pain for the patient. Surgical robotics are used to further decrease the invasiveness of procedures, by using yet smaller and fewer incisions or using natural orifices as entry point. However, many robotic systems still suffer from technical challenges such as sufficient instrument dexterity and payloads, leading to limited adoption in clinical practice. Cable-driven parallel mechanisms (CDPMs) have unique properties, which can be used to overcome existing challenges in surgical robotics. These beneficial properties include high end-effector payloads, efficient force transmission and a large configurable instrument workspace. However, the use of CDPMs in MIS is largely unexplored. This research presents the first structured exploration of CDPMs for MIS and demonstrates the potential of this type of mechanism through the development of multiple prototypes: the ESD CYCLOPS, CDAQS, SIMPLE, neuroCYCLOPS and microCYCLOPS. One key challenge for MIS is the access method used to introduce CDPMs into the body. Three different access methods are presented by the prototypes. By focusing on the minimally invasive access method in which CDPMs are introduced into the body, the thesis provides a framework, which can be used by researchers, engineers and clinicians to identify future opportunities of CDPMs in MIS. Additionally, through user studies and pre-clinical studies, these prototypes demonstrate that this type of mechanism has several key advantages for surgical applications in which haptic feedback, safe automation or a high payload are required. These advantages, combined with the different access methods, demonstrate that CDPMs can have a key role in the advancement of MIS technology.Open Acces

Haptic Device Design and Teleoperation Control Algorithms for Mobile Manipulators

The increasing need of teleoperated robotic systems implies more and more often to use, as slave devices, mobile platforms (terrestrial, aerial or underwater) with integrated manipulation capabilities, provided e.g. by robotic arms with proper grasping/manipulation tools. Despite this, the research activity in teleoperation of robotic systems has mainly focused on the control of either fixed-base manipulators or mobile robots, non considering the integration of these two types of systems in a single device. Such a combined robotic devices are usually referred to as mobile manipulators: systems composed by both a robotic manipulator and a mobile platform (on which the arm is mounted) whose purpose is to enlarge the manipulator’s workspace. The combination of a mobile platform and a serial manipulator creates redundancy: a particular point in the space can be reached by moving the manipulator, by moving the mobile platform, or by a combined motion of both. A synchronized motion of both devices need then to be addressed. Although specific haptic devices explicitly oriented to the control of mobile manipulators need to be designed, there are no commercial solution yet. For this reason it is often necessary to control such as combined systems with traditional haptic devices not specifically oriented to the control of mobile manipulators. The research activity presented in this Ph.D. thesis focuses in the first place on the design of a teleoperation control scheme which allows the simultaneous control of both the manipulator and the mobile platform by means of a single haptic device characterized by fixed base and an open kinematic chain. Secondly the design of a novel cable-drive haptic devices has been faced. Investigating the use of twisted strings actuation in force rendering is the most interesting challenge of the latter activity

Emerging technologies for learning (volume 1)

Collection of 5 articles on emerging technologies and trend