A robot hand testbed designed for enhancing embodiment and functional neurorehabilitation of body schema in subjects with upper limb impairment or loss.

Many upper limb amputees experience an incessant, post-amputation "phantom limb pain" and report that their missing limbs feel paralyzed in an uncomfortable posture. One hypothesis is that efferent commands no longer generate expected afferent signals, such as proprioceptive feedback from changes in limb configuration, and that the mismatch of motor commands and visual feedback is interpreted as pain. Non-invasive therapeutic techniques for treating phantom limb pain, such as mirror visual feedback (MVF), rely on visualizations of postural changes. Advances in neural interfaces for artificial sensory feedback now make it possible to combine MVF with a high-tech "rubber hand" illusion, in which subjects develop a sense of embodiment with a fake hand when subjected to congruent visual and somatosensory feedback. We discuss clinical benefits that could arise from the confluence of known concepts such as MVF and the rubber hand illusion, and new technologies such as neural interfaces for sensory feedback and highly sensorized robot hand testbeds, such as the "BairClaw" presented here. Our multi-articulating, anthropomorphic robot testbed can be used to study proprioceptive and tactile sensory stimuli during physical finger-object interactions. Conceived for artificial grasp, manipulation, and haptic exploration, the BairClaw could also be used for future studies on the neurorehabilitation of somatosensory disorders due to upper limb impairment or loss. A remote actuation system enables the modular control of tendon-driven hands. The artificial proprioception system enables direct measurement of joint angles and tendon tensions while temperature, vibration, and skin deformation are provided by a multimodal tactile sensor. The provision of multimodal sensory feedback that is spatiotemporally consistent with commanded actions could lead to benefits such as reduced phantom limb pain, and increased prosthesis use due to improved functionality and reduced cognitive burden

Doctor of Philosophy

dissertationVirtual environments provide a consistent and relatively inexpensive method of training individuals. They often include haptic feedback in the form of forces applied to a manipulandum or thimble to provide a more immersive and educational experience. However, the limited haptic feedback provided in these systems tends to be restrictive and frustrating to use. Providing tactile feedback in addition to this kinesthetic feedback can enhance the user's ability to manipulate and interact with virtual objects while providing a greater level of immersion. This dissertation advances the state-of-the-art by providing a better understanding of tactile feedback and advancing combined tactilekinesthetic systems. The tactile feedback described within this dissertation is provided by a finger-mounted device called the contact location display (CLD). Rather than displaying the entire contact surface, the device displays (feeds back) information only about the center of contact between the user's finger and a virtual surface. In prior work, the CLD used specialized two-dimensional environments to provide smooth tactile feedback. Using polygonal environments would greatly enhance the device's usefulness. However, the surface discontinuities created by the facets on these models are rendered through the CLD, regardless of traditional force shading algorithms. To address this issue, a haptic shading algorithm was developed to provide smooth tactile and kinesthetic interaction with general polygonal models. Two experiments were used to evaluate the shading algorithm. iv To better understand the design requirements of tactile devices, three separate experiments were run to evaluate the perception thresholds for cue localization, backlash, and system delay. These experiments establish quantitative design criteria for tactile devices. These results can serve as the maximum (i.e., most demanding) device specifications for tactile-kinesthetic haptic systems where the user experiences tactile feedback as a function of his/her limb motions. Lastly, a revision of the CLD was constructed and evaluated. By taking the newly evaluated design criteria into account, the CLD device became smaller and lighter weight, while providing a full two degree-of-freedom workspace that covers the bottom hemisphere of the finger. Two simple manipulation experiments were used to evaluate the new CLD device

Design of a 3D-printed soft robotic hand with distributed tactile sensing for multi-grasp object identification

Tactile object identification is essential in environments where vision is occluded or when intrinsic object properties such as weight or stiffness need to be discriminated between. The robotic approach to this task has traditionally been to use rigid-bodied robots equipped with complex control schemes to explore different objects. However, whilst varying degrees of success have been demonstrated, these approaches are limited in their generalisability due to the complexity of the control schemes required to facilitate safe interactions with diverse objects. In this regard, Soft Robotics has garnered increased attention in the past decade due to the ability to exploit Morphological Computation through the agent's body to simplify the task by conforming naturally to the geometry of objects being explored. This exists as a paradigm shift in the design of robots since Soft Robotics seeks to take inspiration from biological solutions and embody adaptability in order to interact with the environment rather than relying on centralised computation. In this thesis, we formulate, simplify, and solve an object identification task using Soft Robotic principles. We design an anthropomorphic hand that has human-like range of motion and compliance in the actuation and sensing. The range of motion is validated through the Feix GRASP taxonomy and the Kapandji Thumb Opposition test. The hand is monolithically fabricated using multi-material 3D printing to enable the exploitation of different material properties within the same body and limit variability between samples. The hand's compliance facilitates adaptable grasping of a wide range of objects and features integrated distributed tactile sensing. We emulate the human approach of integrating information from multiple contacts and grasps of objects to discriminate between them. Two bespoke neural networks are designed to extract patterns from both the tactile data and the relationships between grasps to facilitate high classification accuracy

Identifying Haptic Exploratory Procedures by Analyzing Hand Dynamics and Contact Force

Haptic exploratory procedures (EPs) are prototypical hand movements that are linked to the acquisition of specific object properties. In studies of haptic perception, hand movements are often classified into these EPs. Here, we aim to investigate several EPs in a quantitative manner to understand how hand dynamics and contact forces differ between them. These dissimilarities are then used to construct an EP identification model capable of discriminating between EPs based on the index finger position and contact force. The extent to which the instructed EPs were distinct, repeatable, and similar across subjects was confirmed by showing that more than 95 percent of the analyzed trials were classified correctly. Finally, the method is employed to investigate haptic exploratory behavior during similarity judgments based on several object properties. It seems that discrimination based on material properties (hardness, roughness, and temperature) yields more consistent classification results compared to discrimination based on the acquisition of shape information. © 2013 IEEE

Doctor of Philosophy

dissertationThe study of haptic interfaces focuses on the use of the sense of touch in human-machine interaction. This document presents a detailed investigation of lateral skin stretch at the fingertip as a means of direction communication. Such tactile communication has applications in a variety of situations where traditional audio and visual channels are inconvenient, unsafe, or already saturated. Examples include handheld consumer electronics, where tactile communication would allow a user to control a device without having to look at it, or in-car navigation systems, where the audio and visual directions provided by existing GPS devices can distract the driver's attention away from the road. Lateral skin stretch, the displacement of the skin of the fingerpad in a plane tangent to the fingerpad, is a highly effective means of communicating directional information. Users are able to correctly identify the direction of skin stretch stimuli with skin displacements as small as 0.1 mm at rates as slow as 2 mm/s. Such stimuli can be rendered by a small, portable device suitable for integration into handheld devices. The design of the device-finger interface affects the ability of the user to perceive the stimuli accurately. A properly designed conical aperture effectively constrains the motion of the finger and provides an interface that is practical for use in handheld devices. When a handheld device renders directional tactile cues on the fingerpad, the user must often mentally rotate those cues from the reference frame of the finger to the world-centered reference frame where those cues are to be applied. Such mental rotation incurs a cognitive cost, requiring additional time to mentally process the stimuli. The magnitude of these cognitive costs is a function of the angle of rotation, and of the specific orientations of the arm, wrist and finger. Even with the difficulties imposed by required mental rotations, lateral skin stretch is a promising means of communicating information using the sense of touch with potential to substantially improve certain types of human-machine interaction

The N170 event-related potential differentiates congruent and incongruent gaze responses in gaze leading

To facilitate social interactions, humans need to process the responses that other people make to their actions, including eye movements that could establish joint attention. Here, we investigated the neurophysiological correlates of the processing of observed gaze responses following the participants’ own eye movement. These observed gaze responses could either establish, or fail to establish, joint attention. We implemented a gaze leading paradigm in which participants made a saccade from an on-screen face to an object, followed by the on-screen face either making a congruent or incongruent gaze shift. An N170 event-related potential was elicited by the peripherally located gaze shift stimulus. Critically, the N170 was greater for joint attention than non-joint gaze both when task-irrelevant (Experiment 1) and task-relevant (Experiment 2). These data suggest for the first time that the neurocognitive system responsible for structural encoding of face stimuli is affected by the establishment of participant-initiated joint attention

Myoelectric forearm prostheses: State of the art from a user-centered perspective

User acceptance of myoelectric forearm prostheses is currently low. Awkward control, lack of feedback, and difficult training are cited as primary reasons. Recently, researchers have focused on exploiting the new possibilities offered by advancements in prosthetic technology. Alternatively, researchers could focus on prosthesis acceptance by developing functional requirements based on activities users are likely to perform. In this article, we describe the process of determining such requirements and then the application of these requirements to evaluating the state of the art in myoelectric forearm prosthesis research. As part of a needs assessment, a workshop was organized involving clinicians (representing end users), academics, and engineers. The resulting needs included an increased number of functions, lower reaction and execution times, and intuitiveness of both control and feedback systems. Reviewing the state of the art of research in the main prosthetic subsystems (electromyographic [EMG] sensing, control, and feedback) showed that modern research prototypes only partly fulfill the requirements. We found that focus should be on validating EMG-sensing results with patients, improving simultaneous control of wrist movements and grasps, deriving optimal parameters for force and position feedback, and taking into account the psychophysical aspects of feedback, such as intensity perception and spatial acuity

Engineering data compendium. Human perception and performance. User's guide

The concept underlying the Engineering Data Compendium was the product of a research and development program (Integrated Perceptual Information for Designers project) aimed at facilitating the application of basic research findings in human performance to the design and military crew systems. The principal objective was to develop a workable strategy for: (1) identifying and distilling information of potential value to system design from the existing research literature, and (2) presenting this technical information in a way that would aid its accessibility, interpretability, and applicability by systems designers. The present four volumes of the Engineering Data Compendium represent the first implementation of this strategy. This is the first volume, the User's Guide, containing a description of the program and instructions for its use

Human operator performance of remotely controlled tasks: Teleoperator research conducted at NASA's George C. Marshal Space Flight Center

The capabilities within the teleoperator laboratories to perform remote and teleoperated investigations for a wide variety of applications are described. Three major teleoperator issues are addressed: the human operator, the remote control and effecting subsystems, and the human/machine system performance results for specific teleoperated tasks

Sensory Communication

Contains table of contents for Section 2, an introduction, reports on ten research projects and a list of publications.National Institutes of Health Grant 5 R01 DC00117National Institutes of Health Grant 5 R01 DC00270National Institutes of Health Grant 5 P01 DC00361National Institutes of Health Grant 2 R01 DC00100National Institutes of Health Grant 7 R29 DC00428National Institutes of Health Grant 2 R01 DC00126U.S. Air Force - Office of Scientific Research Grant AFOSR 90-0200U.S. Navy - Office of Naval Research Grant N00014-90-J-1935National Institutes of Health Grant 5 R29 DC00625U.S. Navy - Office of Naval Research Grant N00014-91-J-145