Hand Configuration Research Articles

From ‘ontological metaphor’ to semiotic make-believe: giving shape and substance to fictive objects of conception with the ‘globe gesture’

Speakers are moving cognizers who engage in bodily acts of conceptualization. The “globe gesture” is among the most spectacular forms of “manual thinking” (Streeck 2009) used in formal talk. A characterization of the kinesic action typical of the “globe gesture” is first provided that shows how “the image of a bounded, supportable object” is created (McNeill 1992) and set up in gesture space. As conceptual objects are created and masses of semantic substance fashioned, visible shape is given to shapeless mental representations. A powerful semiotic trick is performed with a simple cognitive artifact. Interestingly, a willing suspension of disbelief is required of speakers and listeners who must temporarily give up their rational conceptions of visibility, materiality and palpability to watch the symbolic manipulation of invisible objects. The basic expressive properties of the “globe gesture” are next characterized: outlining and isolating objects of conception; neutralizing semantic specification; establishing a joint focus of attention and imagination; shaping, displaying and unifying content; creating a sense of reality and existence through physical presence. Iconic modifications of the standard metaphoric hand configuration, virtuosic elaborations and creative blends are finally examined before reporting the results of an experimental study of the globe gesture’s heuristic properties in a controlled environment. 14 students attending a multimodal “kineflective” seminar used the hand configuration to engage in “choreographic thinking” (Forsythe 2009) and develop a haptic understanding of derivation, nominalization, substantivation, conceptual reification. The globe gesture acted as a facilitator so long as a high degree of generality was maintained but was promptly discarded when words with a strong emotional appeal were introduced (e.g. sadness, madness). Emblems and iconic gestures were spontaneously performed instead.

Rozwój kompetencji fonologicznych dzieci nabywających języki migowe

Deaf and hearing children of deaf parents acquire naturally sign language at the levels of phonology, morphology, syntax and pragmatics. In this article we describe the process of children’s sign development at the level of phonology. On the basis of the sign language structure theory of W. Stokoe, a pioneer researcher of sign linguistics, we distinguish three parameters acquired by children: location (place of articulation), hand configuration (shape of the hand) and movement (hand action). The acquisition of sign phonology is proceed according the rules, whose existence are approved by proper use of parameters and errors at the certain level of sign phonology development. In sign phonology acquisition we can find nonmarked parameters, which are earlier produced by children, distinct, less complex and most frequently occurring in adults utterances; and marked parameters which appear later in child development.

The GRASP Taxonomy of Human Grasp Types

In this paper, we analyze and compare existing human grasp taxonomies and synthesize them into a single new taxonomy (dubbed “The GRASP Taxonomy” after the GRASP project funded by the European Commission). We consider only static and stable grasps performed by one hand. The goal is to extract the largest set of different grasps that were referenced in the literature and arrange them in a systematic way. The taxonomy provides a common terminology to define human hand configurations and is important in many domains such as human–computer interaction and tangible user interfaces where an understanding of the human is basis for a proper interface. Overall, 33 different grasp types are found and arranged into the GRASP taxonomy. Within the taxonomy, grasps are arranged according to 1) opposition type, 2) the virtual finger assignments, 3) type in terms of power, precision, or intermediate grasp, and 4) the position of the thumb. The resulting taxonomy incorporates all grasps found in the reviewed taxonomies that complied with the grasp definition. We also show that due to the nature of the classification, the 33 grasp types might be reduced to a set of 17 more general grasps if only the hand configuration is considered without the object shape/size.

Vision for Prehension in the Medial Parietal Cortex.

In the last 2 decades, the medial posterior parietal area V6A has been extensively studied in awake macaque monkeys for visual and somatosensory properties and for its involvement in encoding of spatial parameters for reaching, including arm movement direction and amplitude. This area also contains populations of neurons sensitive to grasping movements, such as wrist orientation and grip formation. Recent work has shown that V6A neurons also encode the shape of graspable objects and their affordance. In other words, V6A seems to encode object visual properties specifically for the purpose of action, in a dynamic sequence of visuomotor transformations that evolve in the course of reach-to-grasp action.We propose a model of cortical circuitry controlling reach-to-grasp actions, in which V6A acts as a comparator that monitors differences between current and desired hand positions and configurations. This error signal could be used to continuously update the motor output, and to correct reach direction, hand orientation, and/or grip aperture as required during the act of prehension.In contrast to the generally accepted view that the dorsomedial component of the dorsal visual stream encodes reaching, but not grasping, the functional properties of V6A neurons strongly suggest the view that this area is involved in encoding all phases of prehension, including grasping.

Two-Finger Caging of Polygonal Objects Using Contact Space Search

Multifinger caging offers a rigorous and robust object grasping approach. Focusing on two-finger caging, this paper describes an algorithm for finding all two-finger cage formations of planar polygonal objects based on contact-space formulation. The paper shows that two-finger cages have several useful properties in contact space. First, the critical points of the cage representation in the hand's configuration space appear as critical points of the interfinger distance function in contact space. Second, these critical points can be graphically characterized directly on the object's boundary. Third, contact space admits a natural rectangular decomposition such that all critical points lie on the rectangle boundaries, and the sublevel sets of contact space and free space are topologically equivalent. These properties lead to a caging graph that can be readily constructed in contact space. Starting from a desired immobilizing grasp of a polygonal object, the caging graph is searched for the minimal, intermediate, and maximal caging regions surrounding the immobilizing grasp. An example constructed from real-world data illustrates and validates the method.

Fingerspelling as a Novel Gateway into Reading Fluency in Deaf Bilinguals.

Studies have shown that American Sign Language (ASL) fluency has a positive impact on deaf individuals’ English reading, but the cognitive and cross-linguistic mechanisms permitting the mapping of a visual-manual language onto a sound-based language have yet to be elucidated. Fingerspelling, which represents English orthography with 26 distinct hand configurations, is an integral part of ASL and has been suggested to provide deaf bilinguals with important cross-linguistic links between sign language and orthography. Using a hierarchical multiple regression analysis, this study examined the relationship of age of ASL exposure, ASL fluency, and fingerspelling skill on reading fluency in deaf college-age bilinguals. After controlling for ASL fluency, fingerspelling skill significantly predicted reading fluency, revealing for the first-time that fingerspelling, above and beyond ASL skills, contributes to reading fluency in deaf bilinguals. We suggest that both fingerspelling—in the visual-manual modality—and reading—in the visual-orthographic modality—are mutually facilitating because they share common underlying cognitive capacities of word decoding accuracy and automaticity of word recognition. The findings provide support for the hypothesis that the development of English reading proficiency may be facilitated through strengthening of the relationship among fingerspelling, sign language, and orthographic decoding en route to reading mastery, and may also reveal optimal approaches for reading instruction for deaf and hard of hearing children.

Dexterous grasping under shape uncertainty

An important challenge in robotics is to achieve robust performance in object grasping and manipulation, dealing with noise and uncertainty. This paper presents an approach for addressing the performance of dexterous grasping under shape uncertainty. In our approach, the uncertainty in object shape is parametrized and incorporated as a constraint into grasp planning. The proposed approach is used to plan feasible hand configurations for realizing planned contacts using different robotic hands. A compliant finger closing scheme is devised by exploiting both the object shape uncertainty and tactile sensing at fingertips. Experimental evaluation demonstrates that our method improves the performance of dexterous grasping under shape uncertainty.

Grasp planning to maximize task coverage

This paper proposes a task-oriented grasp quality metric based on distribution of task disturbance, which could be used to search for a grasp that covers the most significant part of the disturbance distribution. Rather than using a uniformly distributed task wrench space, this paper models a manipulation task with a non-parametric statistical distribution model built from the disturbance data captured during the task demonstrations. The grasp resulting from maximizing the proposed grasp quality criterion is prone to increasing the coverage of most frequent disturbances. To reduce the computational complexity of the search in a high-dimensional robotic hand configuration space, as well as to avoid the correspondence problem, the candidate grasps are computed from a reduced configuration space that is confined by a set of given thumb placements and thumb directions. The proposed approach has been tested both in simulation and on a real robotic system. In simulation, the approach was validated with a Barrett hand and a Shadow hand in several manipulation tasks. Experiments on a physical robotic platform verified the consistency between the proposed grasp metric and the success rate.

New Methodology for Translation of Static Sign Symbol to Words in Kannada Language

is the mean for data transfer over a medium to interact their expressions with each other. The common mode of communication is vocal speech conversation. The main modes of communication are constraint to vocally disabled individuals. For the communication of such individuals various means of communication is suggested, which are called as sign language. Aim: The aim of sign language alphabets recognition is to provide an easy, efficient and accurate mechanism for automatic translation of static sign (determined by a certain configuration of hand) to textual version in kannada language. Problem Statement: The work presented in this paper goal to develop a system for automatic translation of static gestures of alphabets in kannada sign language. It maps letters, words and expression of a certain language to a set of hand gestures enabling an in individual to communicate by using hands gestures rather than by speaking. The system capable of recognizing sign language symbols can be used as a means of communication with hard of hearing people. Sign of the deaf individual can be captured, recognized and translated to words in kannada language for the benefit of blind people. Approach: It has been divided into two phases firstly, feature extraction phase which in turn uses histogram technique, Hough and Segmentation to extract hand from the static sign. Secondly classification phase uses neural network for training samples. Extreme points were extracted from the segmented hand using star skeletonization and recognition was performed by distance signature. Results: The proposed method was tested on the dataset captured in the closed environment with the assumption that the user should be in the field of view. This study was performed for five different datasets in varying lighting conditions. Conclusion: The developed system is focused with objective of reducing the communication gap between normal people and vocally disabled.

A design approach to the configuration of a prosthetic hand

Purpose – This paper presents a method to elaborate the selections of these parameters to achieve stable grasps. The performance of a prosthetic hand is mainly determined by its mechanical design. However, the effects of the geometric parameters of the hand configuration and the object sizes on the grasp stability are unknown. Design/methodology/approach – First, the thumb functions of human hands are analyzed based on the anatomical model, and the configuration characteristics of the thumbs for typical prosthetic hands are summarized. Then a method of optimizing the thumb configuration is proposed by measuring the kinematic transmission performance of robotics. On the basis of the thumb configuration analysis, a design method of the prosthetic hand configuration is proposed based on form closure theory. The discriminant function of form closure is used to analyze and determine the hand configuration parameters. Findings – An application of this method – the newly developed HIT V prosthetic hand – elaborates the optimization of the thumb configuration and the hand configuration, where the relation between the key hand configuration parameters and the discriminant function on condition of satisfying form closure, sustained by analytical equations and graphs, is revealed and visualized. An experimental verification shows that it is an effective method to design the prosthetic hand configuration available for grasping typical objects in our daily life. Originality/value – The paper shows how to easily determine the geometric dimensions of the palm, phalanges and hand configuration, so that the desired range of object sizes can be obtained.

On Configuration Trajectory Formation in Spatiotemporal Profile for Reproducing Human Hand Reaching Movement.

Most functional reaching activities in daily living generally require a hand to reach the functional position in appropriate orientation with invariant spatiotemporal profile. Effectively reproducing such spatiotemporal feature of hand configuration trajectory in real time is essential to understand the human motor control and plan human-like motion on anthropomorphic robotic arm. However, there are no novel computational models in literature toward reproducing hand configuration-to-configuration movement in spatiotemporal profile. In response to the problem, this paper presents a computational framework for hand configuration trajectory formation based on hierarchical principle of human motor control. The composite potential field is constructed on special Euclidean Group to induce time-varying configuration toward target. The dynamic behavior of hand is described by a second-order kinematic model to produce the external representation of high-level motor control. The multivariate regression relation between intrinsic and extrinsic coordinates of arm, is statistically analyzed for determining the arm orientation in real time, which produces the external representation of low-level motor control. The proposed method is demonstrated in an anthropomorphic arm by performing several highly curved self-reaching movements. The generated configuration trajectories are compared with actual human movement in spatiotemporal profile to validate the proposed method.

The neural basis of non-verbal communication-enhanced processing of perceived give-me gestures in 9-month-old girls.

This study investigated the neural basis of non-verbal communication. Event-related potentials were recorded while 29 nine-month-old infants were presented with a give-me gesture (experimental condition) and the same hand shape but rotated 90°, resulting in a non-communicative hand configuration (control condition). We found different responses in amplitude between the two conditions, captured in the P400 ERP component. Moreover, the size of this effect was modulated by participants’ sex, with girls generally demonstrating a larger relative difference between the two conditions than boys.

Decoding a wide range of hand configurations from macaque motor, premotor, and parietal cortices.

Despite recent advances in decoding cortical activity for motor control, the development of hand prosthetics remains a major challenge. To reduce the complexity of such applications, higher cortical areas that also represent motor plans rather than just the individual movements might be advantageous. We investigated the decoding of many grip types using spiking activity from the anterior intraparietal (AIP), ventral premotor (F5), and primary motor (M1) cortices. Two rhesus monkeys were trained to grasp 50 objects in a delayed task while hand kinematics and spiking activity from six implanted electrode arrays (total of 192 electrodes) were recorded. Offline, we determined 20 grip types from the kinematic data and decoded these hand configurations and the grasped objects with a simple Bayesian classifier. When decoding from AIP, F5, and M1 combined, the mean accuracy was 50% (using planning activity) and 62% (during motor execution) for predicting the 50 objects (chance level, 2%) and substantially larger when predicting the 20 grip types (planning, 74%; execution, 86%; chance level, 5%). When decoding from individual arrays, objects and grip types could be predicted well during movement planning from AIP (medial array) and F5 (lateral array), whereas M1 predictions were poor. In contrast, predictions during movement execution were best from M1, whereas F5 performed only slightly worse. These results demonstrate for the first time that a large number of grip types can be decoded from higher cortical areas during movement preparation and execution, which could be relevant for future neuroprosthetic devices that decode motor plans.

Achondropasia and Dentigerous Cyst- A Coincidental Finding or any Relationship?

Achondropasia and Dentigerous Cyst- A Coincidental Finding or any Relationship?

Development of space perception in relation to the maturation of the motor system in infant rhesus macaques (Macaca mulatta)

To act on the environment, organisms must perceive object locations in relation to their body. Several neuroscientific studies provide evidence of neural circuits that selectively represent space within reach (i.e., peripersonal) and space outside of reach (i.e., extrapersonal). However, the developmental emergence of these space representations remains largely unexplored. We investigated the development of space coding in infant macaques and found that they exhibit different motor strategies and hand configurations depending on the objects' size and location. Reaching-grasping improved from 2 to 4 weeks of age, suggesting a broadly defined perceptual body schema at birth, modified by the acquisition and refinement of motor skills through early sensorimotor experience, enabling the development of a mature capacity for coding space.

Musculoskeletal representation of a large repertoire of hand grasping actions in primates.

Reach-to-grasp tasks have become popular paradigms for exploring the neural origin of hand and arm movements. This is typically investigated by correlating limb kinematic with electrophysiological signals from intracortical recordings. However, it has never been investigated whether reach and grasp movements could be well expressed in the muscle domain and whether this could bring improvements with respect to current joint domain-based task representations. In this study, we trained two macaque monkeys to grasp 50 different objects, which resulted in a high variability of hand configurations. A generic musculoskeletal model of the human upper extremity was scaled and morphed to match the specific anatomy of each individual animal. The primate-specific model was used to perform 3-D reach-to-grasp simulations driven by experimental upper limb kinematics derived from electromagnetic sensors. Simulations enabled extracting joint angles from 27 degrees of freedom and the instantaneous length of 50 musculotendon units. Results demonstrated both a more compact representation and a higher decoding capacity of grasping tasks when movements were expressed in the muscle kinematics domain than when expressed in the joint kinematics domain. Accessing musculoskeletal variables might improve our understanding of cortical hand-grasping areas coding, with implications in the development of prosthetics hands.

Ulnar digits contribution to grip strength in patients with thumb carpometacarpal osteoarthritis is less than in normal controls.

Grip testing is commonly used as an objective measure of strength in the hand and upper extremity and is frequently used clinically as a proxy measure of function. Increasing knowledge of hand biomechanics, muscle strength, and prehension patterns can provide us with a better understanding of the functional capabilities of the hand. The objectives of this study were to determine the contribution of ulnar digits to overall grip strength in individuals with thumb carpometacarpal (CMC) osteoarthritis (OA). Thirty-seven subjects participated in the study. This group consisted of 19 patients with CMC OA (aged 60-88years) and 18 healthy subjects (60-88years). Three hand configurations were used by the subjects during grip testing: use of the entire hand (index, middle, ring, and little fingers) (IMRL); use of the index, middle, and ring fingers (IMR); and use of only the index and middle fingers (IM). Grip strength findings for the two groups found that compared to their healthy counterparts, CMC OA patients had, on average, a strength deficiency of 45.6, 35.5, and 28.8% in IMRL, IMR, and IM, respectively. The small finger contribution to grip is 14.3% and the ring and small finger contribute 34% in subjects with CMC OA. Grip strength decreases as the number of digits contributing decreased in both groups. The ulnar digits contribution to grip strength is greater than one third of total grip strength in subjects with CMC OA. Individuals with CMC OA demonstrate significantly decreased grip strength when compared to their healthy counterparts.

Parsing the Hand in Depth Images

Hand pose tracking and gesture recognition are useful for human-computer interaction, while a major problem is the lack of discriminative features for compact hand representation. We present a robust hand parsing scheme to extract a high-level description of the hand from the depth image. A novel distance-adaptive selection method is proposed to get more discriminative depth-context features. Besides, we propose a Superpixel-Markov Random Field (SMRF) parsing scheme to enforce the spatial smoothness and the label co-occurrence prior to remove the misclassified regions. Compared to pixel-level filtering, the SMRF scheme is more suitable to model the misclassified regions. By fusing the temporal constraints, its performance can be further improved. Overall, the proposed hand parsing scheme is accurate and efficient. The tests on synthesized dataset show it gives much higher accuracy for single-frame parsing and enhanced robustness for continuous sequence parsing compared to benchmarks. The tests on real-world depth images of the hand and human body show the robustness to complex hand configurations of our method and its generalization power to different kinds of articulated objects.

Grasp quality measures: review and performance.

The correct grasp of objects is a key aspect for the right fulfillment of a given task. Obtaining a good grasp requires algorithms to automatically determine proper contact points on the object as well as proper hand configurations, especially when dexterous manipulation is desired, and the quantification of a good grasp requires the definition of suitable grasp quality measures. This article reviews the quality measures proposed in the literature to evaluate grasp quality. The quality measures are classified into two groups according to the main aspect they evaluate: location of contact points on the object and hand configuration. The approaches that combine different measures from the two previous groups to obtain a global quality measure are also reviewed, as well as some measures related to human hand studies and grasp performance. Several examples are presented to illustrate and compare the performance of the reviewed measures.

Real-Time Tracking and Recognition Systems for Interactive Telemedicine Health Services

Recent changes affecting the health industry include the digitization of medical information as well as the exchange of medical information through a network-connected medical infrastructure. In this paper, we propose a real-time tracking and recognition system for interactive telemedicine health services. The proposed method is a methodology for both hand and finger detection applied to posture recognition in telemedicine. The detected hand or finger can be used to implement a non-contact mouse in the machine-to-machine. This technology can be used to control telemedicine health devices such as a public healthcare system, pedometer health information reader, glucose-monitoring device, and blood pressure gauge. Skin color is used to segment the hand region from the background, and the contour is extracted from the segmented hand. Contour analysis provides the locations of the fingertips on the hand. Fingertip tracking is performed using a constant velocity model with a pixel-labeling approach. From the tracking process, several hand features can be extracted and then fed into a finite state classifier to identify the hand configuration. The hand can be classified into many gesture classes or several different movement directions. Using this method, we performed an extensive experiment and obtained a very encouraging result. It is shown that using the method used in previous studies, some of the points are lost, whereas using the proposed method described in this paper, all lost points are recovered with no or little displacement error. Ultimately, this paper provides empirical verification of the adequacy and validity of the proposed system for telemedicine health services. Accordingly, the satisfaction and quality of services will improve gesture recognition for interactive telemedicine health services.