Hand Manipulation Research Articles

Electrotactile Feedback in a Virtual Hand Rehabilitation Platform: Evaluation and Implementation

Tactile feedback plays an important role in hand manipulation, especially in the grasping process which is one of the major functions of the hand. However, few commercially available prosthetic hands or hand motor function rehabilitation systems are equipped with tactile feedback. The absence of suitable tactile feedback modules leads to an inferior rehabilitation performance with a large burden on user training and compromised usability. Thus, it is challenging and essential to integrate a proper tactile feedback module with the existing hand rehabilitation systems to achieve a better control performance and accelerate the rehabilitation process. This paper focuses on the implementation and evaluation of the electrotactile feedback (EF) enhanced rehabilitation system. A virtual hand rehabilitation platform is proposed comprising an surface electromyography (sEMG) acquisition module, an electrotactile stimulation module, a virtual environment with sEMG-driven humanlike hand and numerical feedbacks of grasping force and fingertip deformation, where a closed-loop control is formed. Three different feedback conditions including visual feedback (VF), EF, and no feedback (NF) are compared based on the proposed platform. Experiments were conducted on 10 able-bodied subjects, and multiple quantitative metrics for the rehabilitation performance evaluation including training burden estimation and success rate (SR) of tasks were adopted. Results indicate that the integration of EF is helpful to both reduce the rehabilitation duration and improve the virtual grasping SR in comparison with the NF condition while possessing a better practicality over VF. Note to Practitioners —This paper is motivated by the problem of hand grasp control for rehabilitation purposes, but it also applies to other hand motor function rehabilitation process. Existing hand motor function rehabilitation approaches generally lack a proper feedback and rely on the heavy burden during user training and the users experience. This paper suggests incorporating EF to improve the efficiency and efficacy of the rehabilitation process. The electrical stimulation is driven by the myoelectric-sensing-based force estimation and encoded in a manual scheme to fit each individual involved. In our work, a virtual hand rehabilitation platform is implemented to verify the feasibility of EF in reducing the burden of user training and improving the rehabilitation performance, which allows the expanding of the current system into a broader spectrum of motor function rehabilitation applications. Experiments on able-bodied subjects suggest that the EF in the proposed virtual hand rehabilitation platform is feasible, but it has not been tested on the limb-impaired subjects and confined to a manual encoding of electrical stimulation. In the future research, the design of a general EF enhanced hand rehabilitation platform with a standardized stimulation parameter optimization will be addressed and further validated on the subjects with limb impairments and amputation.

Hand Grip and Load Force Coordination of the Ipsilesional Hand of Chronic Stroke Individuals

Object manipulation depends on a refined control of grip force (GF) and load force (LF). After a brain injury, the GF control is altered in the paretic hand but what happens with the non-paretic hand is still unclear. In this study, we compared the GF control and GF–LF coordination of the non-paretic hand of 10 stroke individuals who suffered right brain damage (RBD) and 10 who suffered left brain damage (LBD), with 20 healthy individuals during lifting and oscillation task, using an instrumented object. GF was recorded with a force transducer, and LF was estimated from the object weight and acceleration. Overall, the ipsilesional hand of stroke individuals, independent of the lesion side, presented similar GF control and GF–LF coordination. However, LBD individuals took longer to start lifting the object, which may be due to the need of more time to obtain somatosensory information from the contact with the object. The findings indicate that stroke individuals preserve their ability to control and coordinate GF and LF when using their ipsilesional hand for object manipulation and the left hemisphere may play an essential role in the processing of somatosensory information needed for the GF control.

Análise microbiológica de manipuladores e superfícies de manipulação de escolas públicas

As doenças transmitidas por alimentos contaminados são ocasionadas principalmente pela falta de higienização adequada das mãos dos manipuladores dos alimentos bem como das superfícies em que estes produtos são manipulados. Teve por objetivo realizar a análise microbiológica das mãos de manipuladores e superfícies de manipulação em escolas de um município do Maranhão. Foram realizadas análises microbiológicas das mãos de dez manipuladores de alimentos e cinco superfícies de manipulação. Foram feitas as determinações da contagem de coliformes totais e termotolerantes, por meio do método de Tubos Múltiplos em Número Mais Provável. Verificou-se que somente um manipulador não apresentou contaminação pelos micro-organismos estudados, e em relação as superfícies de manipulação todas apresentaram contaminação. Portanto verificou-se que nas escolas avaliadas todas apresentaram falhas no processo de higienização das mãos e das superfícies.

Anatomo-functional characterisation of the human “hand-knob”: A direct electrophysiological study

The cortical area within the human primary motor cortex (M1) that hosts the representation of the hand and fingers is known as the ‘hand-knob’ and is essential for voluntary hand movement. The anatomo-functional heterogeneity described within the monkey primary motor cortex (M1) in a rostro-caudal direction suggests an internal subdivision in two sectors originating different systems of connections to the spinal cord. Direct investigation of the human hand-knob has been prevented, so far, by methodological constraints. The unique setting of brain tumour resection with the brain mapping technique in awake patients enables direct electrophysiological investigation of the functional properties of the human hand-knob. Motor-evoked potentials (MEPs) elicited by Direct Electrical Stimulation (DES) at high frequency (HF-DES) delivered along the hand-knob in rostro-caudal direction, i.e., from the central to the precentral sulcus, were recorded from the hand/arm muscles in patients at rest. The sites located near the precentral sulcus identified with HF-DES were then stimulated with low-frequency DES (LF-DES) during a hand manipulation task (HMt) to assess whether DES affected task execution. From the stimulated sites, corticofugal projections and U-shaped tracts connecting with adjacent gyri were traced using diffusion tensor and spherical deconvolution tractography. Analysis of MEPs showed a rostro-caudal gradient of cortical excitability along the hand-knob (the rostral sector being less excitable). Stimulation of rostral sites during the HMt impaired the task by inducing dysfunctional recruitment or, alternatively, suppression of distal muscles. Diffusion tractography showed different patterns of rostro-caudal connectivity for the U-shaped tracts. Overall data suggests, in humans, the anatomo-functional subdivision of the human hand-knob in two sectors, possibly subserving different roles in motor control.

Development of a single-chip elasticity sensor using MEMS-based piezoresistive cantilevers with different tactile properties

In this paper, we propose a micro-electronic-mechanical systems (MEMS)-based tactile sensor that can measure the elasticity of an object without having to measure the contact force and the object’s deformation. In our sensor design, a sensor chip that has three piezoresistive cantilevers is covered by a polydimethylsiloxane (PDMS) pad. The elasticity of an object pressed against the sensor is measured from the ratio of the deformations at different locations of the PDMS pad. One cantilever (C1) is designed to measure the deformation of the center of the PDMS pad, while the other two cantilevers (C2 and C3) are designed to measure the deformations of the outer ends of the PDMS pad. When the sensor is pressed against an object, the ratio of the deformations of the outer ends over that of the center of the PDMS varies depending on the object’s elasticity but not on the pressing force. Therefore, it is possible to measure the object’s elasticity from the ratio of the cantilevers’ outputs. Here, we report on the sensor design, numerical analysis, sensor fabrication, and demonstration of the elasticity measurement using the fabricated sensor. The proposed sensor is expected to be useful in practical applications, including robotic hand manipulation and tissue stiffness discrimination in minimally invasive surgery.

Toward Whole-Hand Kinesthetic Feedback: A Survey of Force Feedback Gloves

Force feedback gloves have found many applications in fields such as teleoperation and virtual reality. In order to enhance the immersive feeling of interaction with remote or virtual environments, glove-like haptic devices are used, which enable users to touch and manipulate virtual objects in a more intuitive and direct way via the dexterous manipulation and sensitive perception capabilities of human hands. In this survey, we aim to identify the gaps between existing force feedback gloves and the desired ones that can provide robust and realistic sensation of the interaction with diverse virtual environments. By examining existing force feedback gloves, the pros and cons of existing design solutions to the major sub-systems including sensing, actuation, control, transmission and structure are discussed. Future research topics are put forward with design challenges being elaborated. Innovative design solutions are needed to enable the utility of wearable haptic gloves in the upcoming virtual reality era.

BCL-13: A 13-DOF Soft Robotic Hand for Dexterous Grasping and In-Hand Manipulation

This letter presents a dexterous soft robotic hand, BCL-13, with 4 fingers and 13 independently actuated joints capable of in-hand manipulation. The iconic dexterity is enabled by a novel soft robotic finger design with three degrees of freedom (DOFs), significantly improving over existing soft actuator dexterity and realizing human-finger-like workspace. The palm is also equipped with a dedicated rotational DOF to enable opposition of fingers. Investigations on human hand model reduction, in-hand manipulation principles, as well as the fabrication procedures of the soft robotic fingers and hand were presented in detail. Dedicated experiments using the fabricated prototypes were conducted to evaluate the effectiveness of the proposed robotic anthropomorphic system via a series of workspace, grasping, and in-hand manipulation tasks. The proposed BCL-13 hand offers a promising design solution to a lightweight, dexterous, affordable, and highly anthropomorphic robotic hand design.

A Tangible Educative 3D Printed Atlas of the Rat Brain.

In biology and neuroscience courses, brain anatomy is usually explained using Magnetic Resonance (MR) images or histological sections of different orientations. These can show the most important macroscopic areas in an animals’ brain. However, this method is neither dynamic nor intuitive. In this work, an anatomical 3D printed rat brain with educative purposes is presented. Hand manipulation of the structure, facilitated by the scale up of its dimensions, and the ability to dismantle the “brain” into some of its constituent parts, facilitates the understanding of the 3D organization of the nervous system. This is an alternative method for teaching students in general and biologists in particular the rat brain anatomy. The 3D printed rat brain has been developed with eight parts, which correspond to the most important divisions of the brain. Each part has been fitted with interconnections, facilitating assembling and disassembling as required. These solid parts were smoothed out, modified and manufactured through 3D printing techniques with poly(lactic acid) (PLA). This work presents a methodology that could be expanded to almost any field of clinical and pre-clinical research, and moreover it avoids the need for dissecting animals to teach brain anatomy.

Response Modality vs. Target Modality: Sensory Transformations and Comparisons in Cross-modal Slant Matching Tasks

Humans constantly combine multi-sensory spatial information to successfully interact with objects in peripersonal space. Previous studies suggest that sensory inputs of different modalities are encoded in different reference frames. In cross-modal tasks where the target and response modalities are different, it is unclear which reference frame these multiple sensory signals are transformed to for comparison. The current study used a slant perception and parallelity paradigm to explore this issue. Participants perceived (either visually or haptically) the slant of a reference board and were asked to either adjust an invisible test board by hand manipulation or to adjust a visible test board through verbal instructions to be physically parallel to the reference board. We examined the patterns of constant error and variability of unimodal and cross-modal tasks with various reference slant angles at different reference/test locations. The results revealed that rather than a mixture of the patterns of unimodal conditions, the pattern in cross-modal conditions depended almost entirely on the response modality and was not substantially affected by the target modality. Deviations in haptic response conditions could be predicted by the locations of the reference and test board, whereas the reference slant angle was an important predictor in visual response conditions.

New kinematics Hessian matrixes of manipulators based on Skew-symmetric matrixes theory

• Propose novel approach for deriving Hessian matrix of PM and its generative mechanisms. • Derive Hessian matrixes of a typical PM with 3 different limbs. • Derive Hessian matrix of hybrid hand and redundant kinematic hybrid manipulator. • Derive angular accelerations and Hessian matrix of 2 typical kinematic limbs. A new approach is proposed for deriving the Hessian matrixes of parallel manipulators and their generative mechanisms using the skew-symmetric matrixes of translational/angular velocities and their combination formulae. First, several necessary skew-symmetric matrixes of the translational/ angular velocities and their combination formulae are derived. Second, the differentiations of the sub-Jacobian matrixes are transformed into a multiplication of a general velocity transposition by sub-Hessian matrixes based on the derived formulae. Third, the sub-Hessian matrixes of a typical parallel manipulator and its generative mechanisms (the hybrid hand and the redundant kinematic hybrid manipulator) as well as their kinematic limbs are derived by differentiating the sub-Jacobian matrixes based on the derived the skew-symmetric matrixes of translational/angular velocities and their combination formulae. Finally, the formulae are derived for solving the Hessian matrixes and the accelerations of the typical parallel manipulator and the generative mechanisms.

Focus on the mechatronics design of a new dexterous robotic hand for inside hand manipulation

SUMMARYThis paper presents a novel tendon-driven bio-inspired robotic hand design for in-hand manipulation. Many dexterous robot hands are able to produce adaptive grasping, but only a few human-sized hands worldwide are able to produce fine motions of the object in the hand. One of the challenges for the near future is to develop human-sized robot hands with human dexterity. Most of the existing hands considered in the literature suffer from dry friction which creates unwanted backlash and non-linearities. These problems limit the accurate control of the fingers and the capabilities of the hand. Such was the case with our first fully actuated dexterous robot hand: the Laboratoire de Mécanique des Solides (LMS) hand.The mechanical design of the hand relies on a tendon-based transmission system. Developing a fully actuated dexterous robot hand requires the routing of the tendons through the finger for the actuation of each joint. This paper focuses on the evolution of the tendon routing; from the LMS hand to the new RoBioSS dexterous hand. The motion transmission in the new design creates purely linear coupling relations between joints and actuators. Experimental results using the same protocol for the previous hand and the new hand illustrate the evolution in the quality of the mechanical design. With the improvements of the mechanical behavior of the robotic fingers, the hand control software could be extensively simplified. The choice of a common architecture for all fingers makes it possible to consider the hand as a collaboration of four serial robots. Moreover, with the transparency of the motor-joint transmissions, we could use robust, industrial-grade cascaded feedback loops for the axis controls.An inside-hand manipulation task concerning the manipulation of a bottle cap is presented at the end of the paper. As proof of the robustness of the hand, demonstrations of the hand's capabilities were carried out continuously over three days at SPS IPC Drives international exhibition in Nuremberg, in November 2016.

Multimodal Human Hand Motion Sensing and Analysis—A Review

Human hand motion (HHM) analysis is an essential research topic in recent applications, especially for dexterous robot hand manipulation learning from human hand skills. It provides important information about the gestures, tactile, speed, and contact force, captured via multiple sensing technologies. This paper introduces a comprehensive survey of current hand motion sensing technologies and analysis approaches in recent emerging applications. First, the nature of HHMs is discussed in terms of simple motions, such as grasps and gestures, and complex motions, e.g., in-hand manipulations and regrasps; second, different techniques for hand motion sensing, including contact-based and noncontact-based approaches, are discussed with comparisons with their pros and cons; then, the state-of-the-art analysis methods are introduced, with a particular focus on the multimodal hand motion sensing and analysis; finally, cutting-edge applications of hand motion analysis are reviewed, with further discussion on facing challenges and new future directions.

Spontaneous imitative movements induced by an illusory embodied fake hand

In the rubber hand illusion (RHI), individuals perceive a fake hand as their own when the hidden real hand and visible fake hand are synchronously stroked. Several RHI studies have reported that visual manipulation of the embodied fake hand inversely affects the perceptual processing of the observer's own hand (e.g., thermal or pain sensitivity). In this study, we examined whether motor manipulation of the fake hand similarly affects the observer's motor system. Our study employed a novel RHI paradigm wherein stroking was interrupted by unexpected movement of the fake hand (i.e., finger spreading) while measuring electroencephalography (EEG). We found that participants often spontaneously moved their hands in accordance with the movement of the fake hand only in the RHI (synchronous) sessions. EEG analyses revealed enhanced neural activation (mu-rhythm desynchronization) of the motor system during observation of the fake hand movement. Moreover, motor activation was greater in the synchronous than in the asynchronous condition and significantly correlated with the feeling of body ownership over the fake hand. These findings provide strong behavioral and neurophysiological evidence of ‘motor back projection’, in which the movement of an illusory embodied body part is inversely transferred to the sensorimotor system of the observer.

Assessment of the praxis circuit in glioma surgery to reduce the incidence of postoperative and long-term apraxia: a new intraoperative test.

OBJECTIVEApraxia is a cognitive-motor deficit affecting the execution of skilled movements, termed praxis gestures, in the absence of primary sensory or motor disorders. In patients affected by stroke, apraxia is associated with lesions of the lateral parietofrontal stream, connecting the posterior parietal areas with the ventrolateral premotor area and subserving sensory-motor integration for the hand movements. In the neurosurgical literature to date, there are few reports regarding the incidence of apraxia after glioma surgery. A retrospective analysis of patients who harbored a glioma around the central sulcus and close to the parietofrontal circuits in depth showed a high incidence of long-term postoperative hand apraxia, impairing the patients' quality of life. To avoid the occurrence of postoperative apraxia, the authors sought to develop an innovative intraoperative hand manipulation task (HMt) that can be used in association with the brain mapping technique to identify and preserve the cortical and subcortical structures belonging to the praxis network.METHODSThe intraoperative efficacy of the HMt was investigated by comparing the incidence of postoperative ideomotor apraxia between patients undergoing mapping with (n = 79) and without (n = 41) the HMt. Patient groups were balanced for all demographic and clinical features.RESULTSIn patients with lesions in the dominant hemisphere, the HMt dramatically reduced the incidence of apraxia, with a higher sensitivity for the ideomotor than for the constructional abilities; patients with lesions in the nondominant hemisphere benefitted from the HMt for both ideomotor and constructional abilities. The administration of the test did not reduce the extent of resection.CONCLUSIONSThe HMt is a safe and feasible intraoperative tool that allowed surgeons to prevent the occurrence of long-term hand apraxia while attaining resection goals for the surgical treatment of glioma.

Optimal Orientation of Text Documents for Reading and Writing

To facilitate interaction with documents in interactive tabletop applications, we explore how the orientation of documents supports efficient reading and writing. In this paper, the orientation of paper documents is systematically investigated in five different experiments. In the first three experiments, 36 Japanese participants, 18 left- and 18 right-handed, explored preferred document orientation for reading horizontal Japanese texts. Experiments 1 and 2 showed that the participants preferred to rotate text documents clockwise if left-handed and counter-clockwise if right-handed relative to their median line. On average, they rotated text documents more when annotating (about 10°) than when reading (about 5°). The difference in document rotation can be explained by the fact that text documents are rotated to facilitate hand manipulation, because they are rotated more when finer hand motions are required. No difference in document angle was found between Japanese horizontal texts and English texts (Experiment 3). In the fourth experiment, we found that right-handed people read text documents faster when they were rotated between –10° and 20° counter-clockwise. Finally, the last experiment explored the effect of document orientation on the performance of transcribing texts. The participants transcribed texts faster when documents were rotated 10° counter-clockwise. In light of the results from these paper-based experiments, we give guidelines for how to present text documents in tabletop applications depending on tasks, documents, and users.

The effect of fine motor skills on handwriting legibility in preschool age children.

[Purpose] The purpose of this study was to examine the effect that fine motor skills have on handwriting legibility in children of preschool age. [Subjects and Methods] The subjects of this study were 52 children of normal growth and development. In order to ascertain handwriting legibility, a Korean alphabet writing assessment was used; to measure fine motor skills, fine motor precision and manual dexterity, sub-items of BOT-2 were measured. Furthermore, in order to measure in-hand manipulation skills, a Functional Dexterity Test was conducted. [Results] The results of the study showed a high level of correlation between fine motor skills and handwriting legibility. The study revealed that the accuracy of hand and in-hand manipulation skills is factors that have an effect on handwriting legibility. [Conclusion] Through the current research, occupational therapists can provide activities that aid the development of fine motor precision and in-hand manipulation skills for children during the instruction and treatment of handwriting to preschool age children, which helps to conduct better legibility in their handwriting.

The effects of modified constraint-induced movement therapy and mirror therapy on upper extremity function and its influence on activities of daily living.

[Purpose] Modified constraint-induced movement therapy and mirror therapy are recognized as stroke rehabilitation methods. The aim of the present study was to determine whether these therapies influence upper extremity function and whether upper extremity function influences the ability to perform activities of daily living in further. [Subjects and Methods] Twenty-eight stroke patients participated in the study. Interventions were administered five times per week for 3 weeks. Activities of daily living or self-exercise were performed after modified constraint-induced movement therapy or mirror therapy, respectively. Analyses were performed on the results of the Manual Function Test and the Korean version of the Modified Barthel Index to determine the factors influencing activities of daily living. [Results] Both groups showed improvement in upper extremity function, but only the modified constraint-induced movement therapy group showed a correlation between upper extremity function and performance in the hygiene, eating, and dressing. The improved hand manipulation function found in the modified constraint-induced movement therapy had statistically significant influences on eating and dressing. [Conclusion] Our results suggest that a patient’s attempts to move the affected side result in improved performance in activities of daily living as well as physical function.

Exploring the existence of better hands for manipulation than the human hand based on hand proportions

Human exhibits the most dexterous manual manipulation among the anthropoids. The sophisticated dexterity of human hand has been linked to its distinctive morphology compared to the nonhuman anthropoids. The human hand is derived from the ancestral hands after longtime evolution. However, there are more possible morphologies that the hands could take during the evolutionary process. It remains unknown whether better hands for manipulation than the human hand exist among these possible hands. To answer the question, the relationship between the manipulative capability and hand morphology need to be investigated in the region of more possible hands. Here we employ a kinematic model to quantitatively assess the manipulative ability of the possible hands from the aspect of hand proportions. The segment length proportions of each possible hand are reconstructed by the major evolutionary patterns of the anthropoid hands. Our results reveal that too long and too short thumbs relative to fingers both hamper the manual dexterity, though the long thumb of human hand is traditionally thought to be beneficial to manipulation. The results promote the understanding of the link between hand morphology and function. Furthermore, we find out the optimal hand for dexterous manipulation within the region reconstructed by the major evolutionary patterns of the anthropoid hands. The optimal hand is more dexterous than the human hand. Compared to the optimal hand, the human hand has shorter metacarpals relative to phalanges, which is thought to be advantageous to the prehensility. It suggests that the human hand is not an organ exclusive for the dexterous manipulation, but a trade-off between multiple functions.

3D-Printed Biomimetic Super-Hydrophobic Structure for Microdroplet Manipulation and Oil/Water Separation.

Biomimetic functional surfaces are attracting increasing attention for various technological applications, especially the superhydrophobic surfaces inspired by plant leaves. However, the replication of the complex hierarchical microstructures is limited by the traditional fabrication techniques. In this paper, superhydrophobic micro-scale artificial hairs with eggbeater heads inspired by Salvinia molesta leaf was fabricated by the Immersed surface accumulation three dimensional (3D) printing process. Multi-walled carbon nanotubes were added to the photocurable resins to enhance the surface roughness and mechanical strength of the microstructures. The 3D printed eggbeater surface reveals interesting properties in terms of superhydrophobilicity and petal effect. The results show that a hydrophilic material can macroscopically behave as hydrophobic if a surface has proper microstructured features. The controllable adhesive force (from 23 μN to 55 μN) can be easily tuned with different number of eggbeater arms for potential applications such as micro hand for droplet manipulation. Furthermore, a new energy-efficient oil/water separation solution based on our biomimetic structures was demonstrated. The results show that the 3D-printed eggbeater structure could have numerous applications, including water droplet manipulation, 3D cell culture, micro reactor, oil spill clean-up, and oil/water separation.

Grasp Stability Analysis of an Isotropic Direct Driven Three-Finger Soft Robot Hand

Grasp stability is considered to be an important aspect in object manipulation of a multifingered robot hand. Multifingered hand contacts the object at some arbitrary locations during the object manipulation and applies the gripping force to hold and manipulate the object without slip. It is desirable to use the optimum gripping force during the grasp manipulation for two reasons; firstly, to prevent the object from damages, secondly, to decrease the cost of the manipulation. With these objectives in mind, a three-fingered soft hand is designed, and gripping force and stability analysis are done experimentally. DC motors are used to actuate the joints of fingers and force sensors are used to measure the internal force at contact points. PID controller is used to controlling the internal force exerted at the contact points, and the control parameters are tweaked until a satisfactory response is achieved. The minimum gripping force required to handle the object with / without external disturbances is measured. The position variables and frictional coefficients are evaluated from the contact forces at the contact points. In future, the optimization algorithm will be integrated to carry out these tasks in constrained and unconstrained environments.