Derek Kamper

North Carolina State University | NCSU

Background Compliant pneumatic actuators possess many characteristics that are desirable for wearable robotic systems. These actuators can be lightweight, integrated with clothing, and accommodate uncontrolled degrees of freedom. These attributes are especially desirable for hand exoskeletons, where the soft actuator can conform to the highly varia...

Background: Manual dexterity is a fundamental motor skill that allows us to perform complex daily tasks. Neuromuscular injuries, however, can lead to the loss of hand dexterity. Although numerous advanced assistive robotic hands have been developed, we still lack dexterous and continuous control of multiple degrees of freedom in real-time. In this...

Myoelectric-based motor intent detection is typically used to interface with assistive devices. However, the intent detection performance is sensitive to interference of electromyogram (EMG) signals. Recently, EMG signals are decomposed into motor units (MU) firing activities, and neuron binary firing activities can be used to predict motor output...

Objective: Robust neural decoding of intended motor output is crucial to enable intuitive control of assistive devices, such as robotic hands, to perform daily tasks. Few existing neural decoders can predict kinetic and kinematic variables simultaneously. The current study developed a continuous neural decoding approach that can concurrently predi...

While fine manual dexterity develops over time, the extent to which children show independent control of their digits in each hand and the impact of perinatal brain injury on this individuation have not been well quantified. Our goal in this study was to assess and compare finger force and movement individuation in 8–14 year old children with hemip...

Neurological injury, such as that resulting from stroke or spinal cord injury, often leads to impairment of the hand. As the hand is critical to performance of so many functional activities, diminished sensorimotor control of the distal upper extremity can profoundly impact quality of life. This is readily apparent in many stroke survivors and indi...

Despite its importance, abnormal interactions between the proximal and distal upper extremity muscles of stroke survivors and their impact on functional task performance has not been well described, due in part to the complexity of upper extremity tasks. In this pilot study, we elucidated proximal–distal interactions and their functional impact on...

Objective: Brain injury is the leading cause of long-term disability worldwide, often resulting in impaired hand function. Brain-machine interfaces (BMIs) offer a potential way to improve hand function. BMIs often target replacing lost function, but may also be employed in neurorehabilitation (nrBMI) by facilitating neural plasticity and functiona...

Background Functional task performance requires proper control of both movement and force generation in three-dimensional space, especially for the hand. Control of force in three dimensions, however, is not explicitly treated in current physical rehabilitation. To address this gap in treatment, we have developed a tool to provide visual feedback o...

Background/purpose: To determine the feasibility of training with electromyographically (EMG) controlled games to improve control of muscle activation patterns in stroke survivors. Methods: Twenty chronic stroke survivors (>6 months) with moderate hand impairment were randomized to train either unilaterally (paretic only) or bilaterally over 9 o...

Purpose: Hemiplegic cerebral palsy (hCP) typically impacts sensorimotor control of the hand, but comprehensive assessments of the hands of children with hCP are relatively rare. This scoping review summarizes the development of hand function for children with hCP. Methods: This scoping review focused on the development of hand function in childr...

Compliant pneumatic systems are well suited for wearable robotic applications. The actuators are lightweight, conformable to irregular shapes, and tolerant of uncontrolled degrees of freedom. These attributes are especially desirable for hand exoskeletons given their space and mass constraints. Creating active digit extension with these exoskeleton...

Stroke is a leading cause of disability in the U.S. Hand impairment is a common consequence of stroke, potentially impacting all facets of life as the hands are the primary means of interacting with the world. Typically, therapy is the prescribed treatment after stroke. However, a majority of stroke survivors have limited recovery and thus chronic...

Background: Diminished sensorimotor control of the hand is one of the most common outcomes following stroke. This hand impairment substantially impacts overall function and quality of life; standard therapy often results in limited improvement. Mechanisms of dysfunction of the severely impaired post-stroke hand are still incompletely understood, th...

Successful grasp requires that grip forces be properly directed between the fingertips and the held object. Changes in digit posture significantly affect the mapping between muscle force and fingertip force. Joint torques must subsequently be altered to maintain the desired force direction at the fingertips. Our current understanding of the roles o...

Introduction Lifespans after the occurrence of a stroke have been lengthening, but most stroke survivors will experience chronic impairment. Directed, repetitive practice may reduce deficits, but clinical access is often limited by a variety of factors, such as transportation. Purpose of the Study To introduce a multiuser virtual reality platform...

Objective To investigate the performance of the less affected upper limb in people with stroke, compared to normative values. To examine less affected upper limb function in those whose pre-stroke dominant limb became paretic and those whose pre-stroke non-dominant limb became paretic. Design Cohort study of chronic stroke survivors (7.2±6.7 years...

Objective: To compare participation and subjective experience of participants in both home-based multi-user VR therapy and home-based single-user VR therapy. Design: Crossover, randomized trial SETTING: Initial training and evaluations occurred in a rehabilitation hospital; the interventions took place in participants' homes PARTICIPANTS: Stroke...

Brain-machine interfaces (BMIs) translate brain signals into control signals for an external device, such as a computer cursor or robotic limb. These signals can be obtained either noninvasively or invasively. Invasive recordings, using electrocorticography (ECoG) or intracortical microelectrodes, provide higher bandwidth, more informative signals....

Upper extremity function is affected by a variety of neurological conditions. Robotic exoskeletons offer a potential solution for motor restoration. However, their systematic adoption is limited by challenges relative to human intention detection and device control. This position paper offers a focused perspective on this topic. That is, on how kno...

Background: Impairment of upper extremity function is a common outcome following stroke, to the detriment of lifestyle and employment opportunities. Yet, access to treatment may be limited due to geographical and transportation constraints, especially for those living in rural areas. While stroke rates are higher in these areas, stroke survivors i...

Stroke survivors often require a lengthy and costly rehabilitation regimen to regain some of the hand function lost due to stroke. Financial, travel, and scheduling issues can limit access to clinical therapy, thereby depriving individuals of care. Interventions are needed which can extend from the clinic into the home. Home-based rehabilitation st...

Finger–thumb coordination is crucial to manual dexterity but remains incompletely understood, particularly following neurological injury such as stroke. While being controlled independently, the index finger and thumb especially must work in concert to perform a variety of tasks requiring lateral or palmar pinch. The impact of stroke on this functi...

Neurological injuries often cause degraded motor control. While rehabilitation efforts typically focus on movement kinematics, abnormal muscle activation patterns are often the primary source of impairment. Muscle-based therapies are likely more effective than joint-based therapy. In this study, we examined the feasibility of biomimetic input mimic...

Stroke survivors often have difficulty creating the proper muscle activation patterns to perform functional tasks. We have developed an electromyographically (EMG)-controlled game to assist stroke survivors in rehabilitating activation patterns. Players must produce specific EMG patterns in order to move a cursor throughout a computer screen. We ra...

Stroke survivors often experience long-term upper extremity impairment. This can greatly impair activities of daily living. Repetitive practice of task-oriented training is thought to be beneficial for rehabilitation, but task practice can be limited by poor hand motor control. The objective of this study is to use a soft robotic glove to facilitat...

Predicting the fingertip force vector resulting from excitation of a given muscle remains a challenging but essential task in finger biomechanical modeling. While the conversion of musculotendon force to fingertip force can significantly be affected by finger posture, current techniques utilizing geometric moment arms may not capture such complex p...

While neurons in primary motor cortex (M1) have been shown to respond to sensory stimuli, exploration of this phenomenon has proven challenging. Accurate and repeatable presentation of sensory inputs is difficult. Here, we describe a novel paradigm to study response to joint motion and fingertip force. We employed a custom exoskeleton to drive inde...

Background: Stroke survivors experience greater strength deficits during finger extension than finger flexion. Prior research indicates relatively little observed weakness is directly attributable to muscle atrophy. Changes in other muscle properties, however, may contribute to strength deficits. Objectives: This study measured muscle fiber conduct...

We present a novel multi-user virtual reality (VR) environment for post-stroke rehabilitation that can be used independently in the home to improve upper extremity motor function. This project represents a collaborative multidisciplinary approach to upper extremity therapy that reinvents engagement with health, social communication and well-being f...

Neurological injury, such as that resulting from stroke or spinal cord injury, often leads to impairment of the hand. Due to the importance of the hand in so many activities of our lives, diminished motor control can profoundly impact quality of life. In the past 25 years especially, robotic and mechatronic technology has been developed to alleviat...

Chronic hand impairment is common following stroke. This paper presents an actuated thumb exoskeleton (ATX) to facilitate research in examining motor control and hand rehabilitation. The ATX presented in this work aims to provide independent bi-directional actuation in each of the 5 degrees of freedom (DOF) of the thumb using a novel flexible shaft...

Many mechatronic devices exist to facilitate hand rehabilitation, however few directly address deficits in muscle activation patterns while also enabling functional task practice. We developed an innovative voice and electromyography-driven actuated (VAEDA) glove, which is sufficiently flexible/portable for incorporation into hand-focused therapy p...

An important aspect of a subject�s perception of virtual objects in a virtual environment is whether the size of the object is perceived as it would be in the physical world, which is named size-constancy. The ability of subjects to appreciate size-constancy in an immersive virtual environment was studied while scene complexity, stereovision and mo...

Background: Hemiparetic stroke survivors often exhibit profound weakness in the digits of the paretic hand, but the relative contribution of potential biomechanical and neurological impairment mechanisms is not known. Establishing sources of impairment would help in guiding treatment. Objective: The present study sought to quantify the role of d...

Date Presented 4/17/2015 We present a task-specific protocol that is occupation-based and has been used in registered clinical trials. Analysis of data from a control group that received only the task-specific protocol indicated significant pre-/postintervention improvements found in the Wolf Motor Function Test.

Stroke is the leading cause of serious, long-term disability in the United States. Impairment of upper extremity function is a common outcome following stroke, often to the detriment of lifestyle and employment opportunities. While the upper extremity is a natural target for therapy, treatment may be hampered by limitations in baseline capability a...

Treatment options for stroke survivors with severe hand impairment are limited. Active task practice can be restricted by difficulty in voluntarily activating finger muscles and interference from involuntary muscle excitation. We developed a portable, actuated glove-orthosis, which could be employed to address both issues. We hypothesized that comb...

Dexterous manipulation of the hand, one of the features of human motor control, is often compromised after stroke, to the detriment of basic functions. Despite the importance of independent movement of the digits to activities of daily living, relatively few studies have assessed the impact of specifically targeting individuated movements of the di...

Background and Purpose: The purpose of this study was to investigate the impact of passive static and cyclical stretching of the fingers on hand function in subacute stroke survivors. Participants: Thirteen stroke survivors, 2-5 months post-incident, with moderate to severe hand impairment took part in the study. Method: Each participant comple...

The extensor apparatus, an aponeurosis that covers the dorsal side of each finger, transmits force from a number of musculotendons to the phalanges. Multiple tendons integrate directly into the structure at different sites and the extensor apparatus attaches to the phalanges at multiple points. Thus, prediction of the force distribution within the...

An anatomically realistic biomechanical model of the index finger was created using a force-based approach in order to predict the isometric fingertip force or dynamic movement based on the forces of 7 index finger musculotendons. The model was validated for static forces through comparison with experimental results from 5 cadaver specimens. The mo...

To investigate the longevity and cumulative impact of multiple sessions of passive, cyclical stretching of the digits on hand function in sub-acute stroke survivors. Before-after trial with intervention repeated on 3 consecutive days SETTING: Research laboratory. Individuals with moderate to severe hand impairment, 2-6 months (Subacute: N=12) and g...

Objective: The purpose of this study was to investigate altered finger-thumb coupling in individuals with chronic hemiparesis post-stroke. Methods: First, an external device stretched finger flexor muscles by passively rotating the metacarpophalangeal (MCP) joints. Subjects then performed isometric finger or thumb force generation. Forces/torques a...

Finger impairment following stroke results in significant deficits in hand manipulation and the performance of everyday tasks. While recent advances in rehabilitation robotics have shown promise for facilitating functional improvement, it remains unclear how best to employ these devices to maximize benefits. Current devices for the hand, however, l...

This chapter reviews work completed by the authors and others to examine the mechanisms of musculotendon force transmission to the index finger and, ultimately, to generation of desired force at or movement of the fingertip. Specifically we examined the roles of finger posture, passive joint impedance, anatomical pulleys, and the extensor hood in m...

Significant functional impairment of the hand is commonly observed in stroke survivors. Our previous studies suggested that the inability to modulate muscle coordination patterns according to task requirements may be substantial after stroke, but these limitations have not been examined directly. In this study, we aimed to characterize post-stroke...

A novel artistic virtual reality (VR) environment was developed and tested for use as a rehabilitation protocol for post-stroke hand rehabilitation therapy. The system was developed by an interdisciplinary team of engineers, art therapists, occupational therapists, and VR artists to improve patients' motivation and engagement. Specific exercises we...

We describe a novel art-empowered Virtual Reality (VR) system designed for hand rehabilitation therapy following stroke. The system was developed by an interdisciplinary team of engineers, art therapists, occupational therapists, and VR artist to improve patient's motivation and engagement. We describe system design, development, and user testing f...

Neurological injury, such as that resulting from stroke or spinal cord injury, often leads to impairment of the hand. Due to the importance of the hand in so many activities of our lives, diminished motor control can adversely affect quality of life, sometimes substantially. In the past 20 years especially, robotic and mechatronic technology has be...

Worldwide there are over 160 million people with severe visual impairment, as defined by visual acuity poorer than 20/200.1 A prominent concern for visually impaired individuals is their limited navigational abilities due to insufficient sensory information about their surrounding environment which results in difficulty with navigating new or compl...

The purpose of this study was to compare the torque production in the paretic and non-paretic hands during isokinetic tasks following stroke. We compared torque and power production at the MCP joint of chronic stroke survivors during isometric and isokinetic tasks. We also recorded surface electromyography (EMG) activity in the forearm muscles. Iso...

Weakness is often profound in the contralesional hand after stroke. Relative contributions of various neural and mechanical mechanisms to this impairment, however, have not been quantified. In this study, the extent of one potential contributor, muscle atrophy, was noninvasively assessed in index finger musculature using ultrasonographic techniques...

This study investigated the potential influence of proximal sensory feedback on voluntary distal motor activity in the paretic upper limb of hemiparetic stroke survivors and the potential effect of voluntary distal motor activity on proximal muscle activity. Ten stroke subjects and 10 neurologically intact control subjects performed maximum volunta...

The objective of this study was to explore motor impairment of the thumb following stroke. More specifically, we quantitatively examined kinetic deficits of the thumb. We anticipated that force deficits would be nonuniformly distributed across the kinetic workspace, due in part to varying levels of difficulty in altering the motor activation patter...

The purpose of this study was to investigate whether active range of finger motion could be increased through the introduction of passive, external extension joint torques in stroke survivors. Five chronic stroke survivors with severe hand impairment resulting from hemiparesis took part in the study. Participants completed 2 experimental sessions i...

The purpose of this study was to investigate the influence of prolonged and repetitive passive range of motion (PROM) stretching of the fingers on hand function in stroke survivors. Fifteen chronic stroke survivors with moderate to severe hand impairment took part in the study. Participants underwent 3 experimental sessions consisting of 30 minutes...

Chronic hand impairment is common following stroke. This paper presents an actuated thumb exoskeleton (ATX) to facilitate research in hand rehabilitation therapy. The ATX presented in this work permits independent bi-directional actuation in each of the 5 degrees-of-freedom (DOF) of the thumb using a mechanism that has 5 active DOF and 3 passive DO...

A pilot study was conducted to test the feasibility of using electromyographic signals to drive an active orthosis for hand therapy after stroke. Five stroke survivors with chronic hemiparesis completed 18 one-hour training sessions over 6 weeks. Activation patterns of a long finger flexor muscle and a long finger extensor muscle controlled an orth...

This paper presents a low-cost virtual-reality environment for training finger individuation in stroke survivors with chronic hand impairment. Users play an ergonomic 5-key virtual piano while receiving either assistance or resistance from a pneumatically actuated glove. The level of assistance and the difficulty of the task can be modulated by a t...

To investigate whether visual feedback of digit force directions for the index fingertip and thumb tip during repeated practice of grip force production can correct the digit force directions for persons with stroke during grip assessments. Following stroke, the paretic fingers generate digit forces with a higher than normal proportion of shear for...

To investigate if, following stroke, sustained involuntary activity after voluntary contraction (e.g., grip) of the long finger flexor muscles of the paretic hand is attributable to augmented serotonin release from brainstem pathways, affecting excitability of spastic motoneurons. This single-dose placebo-controlled study examined whether a seroton...

Finger impairment following stroke results in significant deficit in hand manipulation and the performance of everyday tasks. Recent advances in rehabilitation robotics have shown improvement in efficacy of rehabilitation. Current devices, however, lack the capacity to accurately interface with the human finger at levels of velocity and torque comp...

Despite the importance of the thumb to hand function, little is known about the origins of thumb impairment poststroke. Accordingly, the primary purpose of this study was to assess whether thumb flexors have heightened stretch reflexes (SRs) following stroke-induced hand impairment. The secondary purpose was to compare SR characteristics of thumb f...

In this study, we developed a robust subject-specific electromyography (EMG) pattern classification technique to discriminate intended manual tasks from muscle activation patterns of stroke survivors. These classifications will enable volitional control of assistive devices, thereby improving their functionality. Twenty subjects with chronic hemipa...

While a number of devices have recently been developed to facilitate hand rehabilitation after stroke, most place some restrictions on movement of the digits or arm. Thus, a novel glove was developed which can provide independent extension assistance to each digit while still allowing full arm movement. This pneumatic glove, the PneuGlove, can be u...

This study examined grip force development in individuals with hemiparesis following unilateral stroke. Eleven patients with chronic stroke with severe hand impairment and five age-matched neurologically intact subjects grasped an instrumented object between the index finger and thumb while fingertip forces, digit posture, and muscle electromyograp...

Our virtual environment represents the pre-clinical phase of an ongoing research project using a pneumatically actuated glove, head/arm tracking, and a head mounted display to facilitate hand rehabilitation in stroke survivors. This is a collaborative, interdisciplinary project at the Rehabilitation Institute of Chicago involving a team of engineer...

Stroke is the leading cause of permanent adult disability in the U.S., frequently resulting in chronic motor impairments. Rehabilitation of the upper limb, particularly the hand, is especially important as arm and hand deficits post-stroke limit the performance of activities of daily living and, subsequently, functional independence. Hand rehabilit...

The article investigated whether joint postures affect index finger muscle activation patterns. Ten subjects attempted to produce submaximal isometric forces in six orthogonal directions (palmar, dorsal, abduction, adduction, distal and proximal) at each of 9 different joint postures. Activation patterns were recorded from intramuscular electrodes...

An externally actuated glove, controlled by a microprocessor, is being developed to assist finger extension in stroke survivors. The goal of this device is to allow repeated practice of specific tasks for hand therapy in a home environment. The user can control the device by three different means: voice recognition, electromyography, or manual cont...

Hand impairment is common following stroke and is often resistant to traditional therapy methods. Successful interventions have stressed the importance of repeated practice to facilitate rehabilitation. Thus, we have developed a servo-controlled glove to assist extension of individual digits to promote practice of grasp-and-release movements with t...

Neural coupling of proximal and distal upper limb segments may have functional implications in the recovery of hemiparesis after stroke. The goal of the present study was to investigate whether the stretch reflex response magnitude of spastic finger flexor muscles poststroke is influenced by sensory input from the shoulder and the elbow and whether...

Stroke is a leading cause of long-term disability in the United States and the third most frequent cause of death, following diseases of the heart and cancer [1]. Of the more than 700,000 Americans who experience a stroke each year [1], two-thirds survive [2]. Currently there are more than five million stroke survivors in the U.S. [1], many of whom...

Many stroke survivors experience chronic upper extremity impairment that leads to significant functional limitations. Especially for those with more severe impairment, therapeutic treatment may have limited effect. Thus, the introduction of assistive techniques, such as powered orthoses, may prove more beneficial in improving function. A challenge,...

An externally actuated glove, controlled by a microprocessor, is being developed to assist finger extension in stroke survivors. The goal of this device is to allow repeated practice of specific tasks for hand therapy in the home environment. The device allows the user three control modes: voice recognition, electromyography or manual. These modes...

Stroke survivors' difficulty in releasing grasped objects may be attributable not only to impaired finger extension but also to delays in terminating activity in the gripping flexor muscles. This study was undertaken 1) to quantify the time needed to initiate and terminate grip muscular activity following stroke and 2) to examine effects of arm sup...