A Mechanical Hand-Tracking System With Tactile Feedback Designed for Telemanipulation

In this paper, we present a mechanical hand-tracking system with tactile feedback designed for fine manipulation in teleoperation scenarios. Alternative tracking methods based on artificial vision and data gloves have become an asset for virtual reality interaction. Yet, occlusions, lack of precision, and the absence of effective haptic feedback beyond vibrotactile still appear as a limit for teleoperation applications. In this work, we propose a methodology to design a linkage mechanism for hand pose tracking purposes, preserving complete finger mobility. Presentation of the method is followed by design and implementation of a working prototype, and by evaluation of the tracking accuracy using optical markers. Moreover, a teleoperation experiment involving a dexterous robotic arm and hand was proposed to ten participants. It investigated the effectiveness and repeatability of the hand tracking with combined haptic feedback during a proposed pick and place manipulation tasks.

An Assistive Soft Wrist Exosuit for Flexion Movements With an Ergonomic Reinforced Glove

Soft exosuits are a promising solution for the assistance and augmentation of human motor abilities in the industrial field, where the use of more symbiotic wearable robots can avoid excessive worker fatigue and improve the quality of the work. One of the challenges in the design of soft exosuits is the choice of the right amount of softness to balance load transfer, ergonomics, and weight. This article presents a cable-driven based soft wrist exosuit for flexion assistance with the use of an ergonomic reinforced glove. The flexible and highly compliant three-dimensional (3D)-printed plastic structure that is sewn on the glove allows an optimal force transfer from the remotely located motor to the wrist articulation and to preserve a high level of comfort for the user during assistance. The device is shown to reduce fatigue and the muscular effort required for holding and lifting loads in healthy subjects for weights up to 3 kg.

Design Requirements of Generic Hand Exoskeletons and Survey of Hand Exoskeletons for Rehabilitation, Assistive, or Haptic Use

Most current hand exoskeletons have been designed specifically for rehabilitation, assistive, or haptic applications to simplify the design requirements. Clinical studies on poststroke rehabilitation have shown that adapting assistive or haptic applications into physical therapy sessions significantly improves the motor learning and treatment process. The recent technology can lead to the creation of generic hand exoskeletons that are application-agnostic. In this paper, our motivation is to create guidelines and best practices for generic exoskeletons by reviewing the literature of current devices. First, we describe each application and briefly explain their design requirements, and then list the design selections to achieve these requirements. Then, we detail each selection by investigating the existing exoskeletons based on their design choices, and by highlighting their impact on application types. With the motivation of creating efficient generic exoskeletons in the future, we finally summarize the best practices in the literature.

On the edge between soft and rigid: an assistive shoulder exoskeleton with hyper-redundant kinematics

In this paper, we present a prototype of an innovative portable shoulder exoskeleton for human assistance and augmentation. The device provides torques to flexion/extension movements of the shoulder, compensating for gravitational forces, and is passively compliant along the remaining degrees of freedom letting the shoulder moving along them. The novelty of our system is a flexible link, made of a hyper-redundant passive structure, that avoids joint misalignment by adapting to the complex movements of the humerus head, similarly to a soft component. The flexible link is compliant to rotations around one axis but rigid around the other two axes, allowing transmission of flexion/extension torque but kinematically transparent along the remaining degrees of freedom. The device is light weight and allows to cover around the 82% of the shoulder flexion/extension range of motion. The exoskeleton was tested on a cohort of 5 healthy subjects, monitoring shoulder kinematics, interaction forces and acquiring the electromyography of three major muscles contributing to shoulder flexion. During both static postures and dynamic movements, assistance from the exoskeleton resulted in a significant reduction of muscular effort in the anterior (-32.2% in static, -25.3% in dynamic) and medial deltoid (56.9% in static, -49.6% in dynamic) and an average reduction of the biceps brachii.

Wearable Haptics and Immersive Virtual Reality Rehabilitation Training in Children With Neuromotor Impairments

The past decade has seen the emergence of rehabilitation treatments using virtual reality (VR) environments although translation into clinical practice has been limited so far. In this paper, an immersive VR rehabilitation training system endowed with wearable haptics is proposed for children with neuromotor impairments: it aims to enhance involvement and engagement of patients, to provide congruent multi-sensory afferent feedback during motor exercises and to benefit from the flexibility of VR in adapting exercises to the patient's need. An experimental rehabilitation session conducted with children with cerebral palsy (CP) and developmental dyspraxia (DD) has been performed to evaluate the usability of the system and proof of concept trial of the proposed approach. We compared CP/DD performance with both typically developing children and adult control group. Results show the system was compliant with different levels of motor skills and allowed patients to complete the experimental rehabilitation session, with performance varying according to the expected motor abilities of different groups. Moreover, a kinematic assessmentbased on the presented system has been designed. Obtained results reflected different motor abilities of patients and participants, suggesting suitability of the proposed kinematic assessment as a motor function outcome.

Wearable Haptic Systems for the Fingertip and the Hand: Taxonomy, Review, and Perspectives

In the last decade, we have witnessed a drastic change in the form factor of audio and vision technologies, from heavy and grounded machines to lightweight devices that naturally fit our bodies. However, only recently, haptic systems have started to be designed with wearability in mind. The wearability of haptic systems enables novel forms of communication, cooperation, and integration between humans and machines. Wearable haptic interfaces are capable of communicating with the human wearers during their interaction with the environment they share, in a natural and yet private way. This paper presents a taxonomy and review of wearable haptic systems for the fingertip and the hand, focusing on those systems directly addressing wearability challenges. The paper also discusses the main technological and design challenges for the development of wearable haptic interfaces, and it reports on the future perspectives of the field. Finally, the paper includes two tables summarizing the characteristics and features of the most representative wearable haptic systems for the fingertip and the hand.

Integration of serious games and wearable haptic interfaces for Neuro Rehabilitation of children with movement disorders: A feasibility study

The past decade has seen the emergence of rehabilitation treatments using virtual reality environments. One of the advantages in using this technology is the potential to create positive motivation, by means of engaging environments and tasks shaped in the form of serious games. In this work, we propose a novel Neuro Rehabilitation System for children with movement disorders, that is based on serious games in immersive virtual reality with haptic feedback. The system design aims to enhance involvement and engagement of patients, to provide congruent multi-sensory afferent feedback during motor exercises, and to benefit from the flexibility of virtual reality in adapting exercises to the patient's needs. We present a feasibility study of the method conducted through an experimental rehabilitation session in a group of 4 children with Cerebral Palsy and Developmental Dyspraxia, 4 Typically Developing children and 4 healthy adults. Subjects and patients were able to accomplish the proposed rehabilitation session and average performance of the motor exercises in patients were lower, although comparable, to healthy subjects. Together with positive comments reported by children after the rehabilitation session, results are encouraging for application of the method in a prolonged rehabilitation treatment.

A 3-RSR Haptic Wearable Device for Rendering Fingertip Contact Forces

A novel wearable haptic device for modulating contact forces at the fingertip is presented. Rendering of forces by skin deformation in three degrees of freedom (DoF), with contact-no contact capabilities, was implemented through rigid parallel kinematics. The novel asymmetrical three revolute-spherical-revolute (3-RSR) configuration allowed compact dimensions with minimum encumbrance of the hand workspace. The device was designed to render constant to low frequency deformation of the fingerpad in three DoF, combining light weight with relatively high output forces. A differential method for solving the non-trivial inverse kinematics is proposed and implemented in real time for controlling the device. The first experimental activity evaluated discrimination of different fingerpad stretch directions in a group of five subjects. The second experiment, enrolling 19 subjects, evaluated cutaneous feedback provided in a virtual pick-and-place manipulation task. Stiffness of the fingerpad plus device was measured and used to calibrate the physics of the virtual environment. The third experiment with 10 subjects evaluated interaction forces in a virtual lift-and-hold task. Although with different performance in the two manipulation experiments, overall results show that participants better controlled interaction forces when the cutaneous feedback was active, with significant differences between the visual and visuo-haptic experimental conditions.

New generation emerging technologies for neurorehabilitation and motor assistance

This paper illustrates the application of emerging technologies and human-machine interfaces to the neurorehabilitation and motor assistance fields. The contribution focuses on wearable technologies and in particular on robotic exoskeleton as tools for increasing freedom to move and performing Activities of Daily Living (ADLs). This would result in a deep improvement in quality of life, also in terms of improved function of internal organs and general health status. Furthermore, the integration of these robotic systems with advanced bio-signal driven human-machine interface can increase the degree of participation of patient in robotic training allowing to recognize user's intention and assisting the patient in rehabilitation tasks, thus representing a fundamental aspect to elicit motor learning.

An EMG-Controlled Robotic Hand Exoskeleton for Bilateral Rehabilitation

This paper presents a novel electromyography (EMG)-driven hand exoskeleton for bilateral rehabilitation of grasping in stroke. The developed hand exoskeleton was designed with two distinctive features: (a) kinematics with intrinsic adaptability to patient's hand size, and (b) free-palm and free-fingertip design, preserving the residual sensory perceptual capability of touch during assistance in grasping of real objects. In the envisaged bilateral training strategy, the patient's non paretic hand acted as guidance for the paretic hand in grasping tasks. Grasping force exerted by the non paretic hand was estimated in real-time from EMG signals, and then replicated as robotic assistance for the paretic hand by means of the hand-exoskeleton. Estimation of the grasping force through EMG allowed to perform rehabilitation exercises with any, non sensorized, graspable objects. This paper presents the system design, development, and experimental evaluation. Experiments were performed within a group of six healthy subjects and two chronic stroke patients, executing robotic-assisted grasping tasks. Results related to performance in estimation and modulation of the robotic assistance, and to the outcomes of the pilot rehabilitation sessions with stroke patients, positively support validity of the proposed approach for application in stroke rehabilitation.

Beaming: an asymmetric telepresence system

The Beaming project recreates, virtually, a real environment; using immersive VR, remote participants can visit the virtual model and interact with the people in the real environment. The real environment doesn't need extensive equipment and can be a space such as an office or meeting room, domestic environment, or social space.

A fully immersive set-up for remote interaction and neurorehabilitation based on virtual body ownership

Although telerehabilitation systems represent one of the most technologically appealing clinical solutions for the immediate future, they still present limitations that prevent their standardization. Here we propose an integrated approach that includes three key and novel factors: (a) fully immersive virtual environments, including virtual body representation and ownership; (b) multimodal interaction with remote people and virtual objects including haptic interaction; and (c) a physical representation of the patient at the hospital through embodiment agents (e.g., as a physical robot). The importance of secure and rapid communication between the nodes is also stressed and an example implemented solution is described. Finally, we discuss the proposed approach with reference to the existing literature and systems.

The contribution of cutaneous and kinesthetic sensory modalities in haptic perception of orientation

The aim of this study was to understand the integration of cutaneous and kinesthetic sensory modalities in haptic perception of shape orientation. A specific robotic apparatus was employed to simulate the exploration of virtual surfaces by active touch with two fingers, with kinesthetic only, cutaneous only and combined sensory feedback. The cutaneous feedback was capable of displaying the local surface orientation at the contact point, through a small plate indenting the fingerpad at contact. A psychophysics test was conducted with SDT methodology on 6 subjects to assess the discrimination threshold of angle perception between two parallel surfaces, with three sensory modalities and two shape sizes. Results show that the cutaneous sensor modality is not affected by size of shape, but kinesthetic performance is decreasing with smaller size. Cutaneous and kinesthetic sensory cues are integrated according to a Bayesian model, so that the combined sensory stimulation always performs better than single modalities alone.

Ethanol-induced decrease of the expression of glucose transport protein (Glut3) in the central nervous system as a predisposing condition to apoptosis: the effect of age

We measured the effect of chronic ethanol administration on the expression of Glut3 in the cerebellum and hippocampus of adult and old rats. Glut3 expression significantly decreased in aging, in ethanol-treated rats vs. age-matched controls, and in adult- vs. old ethanol-treated rats. These findings lend consistent support to the hypothesis that disturbances of glucose metabolism due to ethanol may constitute an unfavorable condition predisposing to neuronal death.

Age-related effects of moderate alcohol consumption on GAP-43 levels in rat hippocampus

The effects of moderate intake of ethanol and ageing were investigated on the levels of the growth-associated protein GAP-43, whose expression has been used as an indicator of axonal growth during development, regeneration and remodelling of synaptic connections. Groups of female Wistar rats (12 and 24 months of age), were alcohol-fed for one month while age-matched control groups received an isocaloric diet. A quantitative evaluation of GAP-43 was performed in hippocampus and in hippocampal selected areas in view of the vulnerability of this complex to alcohol aggression by means of two different methods, namely Western blot analysis and immunohistochemistry. While the former measures total extractable GAP-43, the latter allows visualisation of in situ changes in topographical distribution of GAP-43. Western blot analysis revealed an age-dependent reduction (-47%) and an ethanol-associated increase (81%) of GAP-43 demonstrated only in the old group. Conversely, quantitative immunohistochemistry of GAP-43 in the entire hippocampus showed a non-significant ethanol-related decrement in 24-month-old rats (-30%), although the age-dependent reduction was confirmed. Ageing was associated with a decrement of GAP-43 immunostaining in CA3 stratum radiatum (CA3) and in inner molecular layer of dentate gyrus (IML). Treatment determined a decrease of GAP-43 immunostaining in adult rat CA3 and IML and no change in CA1 stratum radiatum (CA1). Our results suggest that immunohistochemistry evaluation underestimates GAP-43 levels in ethanol-treated animals possibly as a consequence of conformational changes induced by alcohol, resulting in non-targeting of the specific antibody. Western blot analysis demonstrate that although there is a reduction of GAP-43 levels in hippocampus of aged rats, this structure retain a remarkable potential to compensate for ethanol toxicity during ageing.

Succinic dehydrogenase activity in human muscle mitochondria during aging: a quantitative cytochemical investigation

A quantitative cytochemical study has been carried out on succinic dehydrogenase (SDH) activity in biopsy samples of vastus lateralis (VL) and anterior tibialis (AT) muscles from healthy men undergoing orthopaedic surgery. According to their age, the patients were divided into: young (25.0+/-4.4 years), middle-aged (50.4+/-7.5 years) and old (75.5+/-3.9 years) groups. Bioptically excised samples were processed for copper ferrocyanide preferential SDH cytochemistry. By a computer-assisted image analyser, we calculated the ratio (R): overall area of the precipitates due to the enzyme activity/area of each mitochondrion. No significant difference was found among the three age groups, despite an 8% increase of R in the adult vs. the other groups. R values are related to mitochondrial morphofunctional features since they may be modulated by enzyme activity and the physico-chemical conditions of the organelle membranes. Thus, R quantitation enables to estimate the mitochondrial capacities for adenosinetriphosphate provision. In this context, our present findings confirm previous data reporting a substantial age-related stability of muscle mitochondrial enzyme levels. In aging, energy-deficient sarcomeres are supported to be negatively selected and eliminated, while the surviving ones appear to maintain an adequate SDH activity.

Mapping of mitochondrial metabolic competence by cytochrome oxidase and succinic dehydrogenase cytochemistry

To map the mitochondrial capacity to provide adenosine triphosphate (ATP), the activities of cytochrome oxidase (COX) and succinic dehydrogenase (SDH) were respectively evidenced by diaminobenzidine (DAB) and copper ferrocyanide cytochemical techniques in the cerebellar cortex of adult rats. Sampling of the positive mitochondria was carried out by the disector procedure. The ratio (R) overall area of the precipitates due to COX activity within the single mitochondrion/area of the same organelle was automatically calculated to estimate enzyme activity vs mitochondrial size. The number of SDH-positive mitochondria/microm(3) of tissue (numeric density, Nv) was morphometrically calculated. Cytochemistry of key enzymes of the respiratory chain enables measurement of the actual capacity of individual mitochondria to provide ATP. This quantitative estimation allows morphofunctional mapping of the mitochondrial metabolic competence in discrete tissue and/or cellular compartments. (J Histochem Cytochem 49:1191-1192, 2001)

Cellular distribution of GAP-43 mRNA in hippocampus and cerebellum of adult rat brain by in situ RT-PCR

The growth-associated protein GAP-43 is a presynaptic membrane phosphoprotein that plays a key role in guiding the growth of axons and in modulating the formation of new synapses. To identify the cells that synthesize GAP-43 mRNA, we applied direct in situ reverse transcription-polymerase chain reaction (in situ RT-PCR) in cerebellum and hippocampus of adult rat brain. In situ RT-PCR revealed GAP-43 mRNA in cerebellar granule cells, in Purkinje cells and in some interneurons of the molecular layer. Previous in situ hybridization studies had demonstrated a dense label throughout the granular layer of the cerebellar cortex but no labeling of other cerebellar neurons. Hippocampal cells showing distinct GAP-43 mRNA signal after in situ RT-PCR were CA1 and CA3 pyramidal neurons, CA4 hilar cells, and dentate gyrus granule cells, whereas in situ hybridization studies had detected GAP-43 mRNA only in CA3 and CA1 pyramidal neurons. Our data indicate that GAP-43 mRNA is widely distributed, suggesting that many cell types are potentially involved in synaptic plasticity events. (J Histochem Cytochem 49:1195-1196, 2001)

Distribution of map2 in hippocampus and cerebellum of young and old rats by quantitative immunohistochemistry

The microtubule-associated protein MAP2 is a cytoskeletal protein that plays a regulatory role in neuronal plasticity and in maintaining the morphology of differentiated neurons. MAP2 distribution was assessed in hippocampus and cerebellum of young and old rats by quantitative immunohistochemistry. In old vs young rats, densitometric analysis showed a significant decrease of MAP2 immunoreactivity in the hippocampus CA1 field (-93%), whereas no difference was found in cerebellar MAP2 distribution. These preliminary data suggest that in areas of the brain involved in memory acquisition and consolidation, MAP2-dependent neuroplasticity and structural integrity are significantly decreased in aging.

Quantitative cytochemical mapping of mitochondrial enzymes in rat cerebella

Mitochondrial metabolic competence, defined as the organelle's capacity to provide adequate amounts of ATP in due time, appears to constitute an important determinant in several biological processes and pathological conditions. Thus, the assessment of the metabolic efficiency of the mitochondrial population in a given tissue area or cellular compartment may provide clues to identifying alterations of the cellular bioenergetic machinery, which may constitute a predisposing condition leading to impaired organ and system functions. In the cerebellar cortex of adult rats, the activities of the enzymes cytochrome oxidase (COX) and succinic dehydrogenase (SDH) were, respectively, evidenced by means of the diaminobenzidine and copper ferrocyanide preferential cytochemical techniques. At the electron microscope, the activities of these two key molecules of the respiratory chain were clearly visualised as dark precipitates at the inner mitochondrial membrane sites where COX and SDH are located. By means of the disector method, unbiased mitochondrial samplings were carried out to measure: the number of mitochondria/microm(3) of tissue (numeric density: Nv); the mitochondrial volume fraction/microm(3) of tissue (volume density: Vv) and the average mitochondrial volume (V) both on COX- and SDH-positive organelles in the cerebellar glomeruli and Purkinje cells, respectively. The ratio R (total area of the precipitates due either to COX or SDH activity within the single mitochondrion/area of the same organelle) was also evaluated to get information on the enzyme activity related to mitochondrial size.The documented accumulation of mutant mitochondrial DNA particularly in postmitotic cells results in a marked heteroplasmy (mixtures of normal and mutated genomes) at mitochondrial and cellular levels, thus the cellular potential for energy production is demanded to a mosaic of organelles with different functional capabilities. Assessment of the mitochondrial mosaic outline by means of quantitative cytochemistry of key enzymes of the respiratory chain, such as COX and SDH, may allow for the morphofunctional metabolic mapping of mitochondrial efficiency in discrete cellular or tissue compartments.

Quantitative immunohistochemistry of glucose transport protein (Glut3) expression in the rat hippocampus during aging

Immunohistochemistry of Glut3 (45 kD), an integral membrane peptide mediating the transport of glucose in neurons, was carried out in the hippocampus of 3- and 28-month-old rats to assess the effect of age on energy metabolism. Free-floating sections of fixed-frozen hippocampi were processed for quantitative immunohistochemistry of Glut3. A rabbit affinity-purified antibody identified Glut3 immunoreactivity. Glut3 staining was intense in neuropil, axons, and dendrites, whereas nerve cell bodies were unstained. With aging, Glut3 reactivity was significantly decreased in the inner molecular layer of the hippocampal dentate gyrus (-46%) and the mossy fibers of the CA3 sector (-34%), whereas the stratum radiatum of CA1 did not show any difference due to age. These data document an age-dependent decrease in Glut3 expression in discrete areas of rat hippocampus. Glut3 constitutes the predominant glucose transporter in neurons and is found abundantly in regions with high synaptic density characterized by frequent bursts of function-adequate metabolic activity. Our findings therefore lend further support to the critical role of an impaired metabolism in age-related brain dysfunctions and disease.(J Histochem Cytochem 49:671-672, 2001)