Five-fingered Hand Research Articles

Long-Term Functional and Radiological Results in Tonkin Type 3B Thumb Hypoplasia Treated With Nonvascularized Toe Phalanx Transfer as an Alternative to Pollicization

Parents of children with hypoplastic thumbs often reject the option of pollicization for various reasons and enquire about alternate choices. Our study aimed to assess the outcome in children who underwent nonvascularized toe phalanx transfer for Tonkin type 3B thumb hypoplasia and compare it with a similar cohort of children treated with pollicization. At an average follow-up of 7 years for toe phalanx transfer and 6 years of pollicization, five children from each group were tested for thumb length, stability of the first carpometacarpal (CMC) joint, mobility, opposition, and donor-site morbidity. Parents were asked to report improvements in function and appearance. All cases were Tonkin type 3B thumb hypoplasia. The CMC joint was found to be stable in all children, and the Kapandji score was 6 in 3 children and 5 in 2 children with toe phalanx transfer compared to 9 in all children with pollicization. The average palmar abduction was 24°, and the average radial abduction was 36° in the toe phalanx transfer group compared to 40° and 45°, respectively, in children with pollicization. The average thumb length was 50.8% of the index finger's proximal phalanx in the toe phalanx group compared to 60 % in the pollicization group. The mean visual analog scale scores for the thumb's function and appearance were 6.8 and 6.4, respectively, compared to 9.2 and 8.8, respectively, in the pollicization group. No resorption was noted in the donor phalanx at a mean follow-up of 7 years with no donor-site morbidity other than mild shortening of the toes. We noted increased palmar abduction and radial abduction in the pollicization group. No resorption was noted in the donor toe phalanx at the longest follow-up of 9 years. Toe phalanx can be considered an alternative for those children in whom a five-finger hand is a priority. Therapeutic V.

Non-vascularized metatarsal transfer for thumb hypoplasia: a medium- to long-term retrospective study of 41 patients.

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Modular Bioinspired Hand with Multijoint Rigid-Soft Finger Possessing Proprioception.

Soft robot hands have the advantage of remarkable adaptability for grasping. Especially for the soft and fragile objects, soft fingers had presented their much excellent potential compared with their rigid counterparts. However, less degree of freedom, lower force output, lack of proprioception, and poor controllability still limit the application. Inspired by the anatomical structure of the human hand and following the idea of combining soft joints, rigid skeletons and embedded soft curvature sensors, modular dexterous hands composed of multijoint fingers are proposed in this study. Each finger has three quasi-joints, in which metacarpophalangeal soft-joint can realize adduction/abduction and bending motions, and distal two interphalangeal soft-joints are actuated by one actuator. Similar to human hand, soft-joint so-called quasi-joint has a short length of constant curvature segment. The integrated Indium Gallium Alloy sensors with Kelvin Bridge for proprioception can accurately detect joint angles, while closed-loop control based on proprioception was accomplished. Kinematics and statics modeling method of the rigid-soft finger is proposed. To further verify the performance of this design, prototypes of three-fingered and five-fingered hands are developed. The multifingered hands had demonstrated their capability of adaptive grasp and dexterous manipulation, while the force output of the three-fingered hand is up to 31.82 N, and 32 grasp types had accomplished by the five-fingered hand.

Development of Self-Powered 5-Finger Pneumatically Driven Hand Prosthesis Using Supination of Forearm

Recently, myoelectric hand prostheses produced by the combination of 3D-CAD and printer have gained attention. 3D printing of hand prosthesis has resulted in cost reduction. However, when an electric actuator with reduction gears is used as the driving source of the hand prosthesis, the joint rigidity becomes high; therefore, compliance control is required to grasp soft target objects. In this study, we propose a pneumatically driven hand prosthesis using a flexible bellows actuator. The hand prosthesis is lightweight and inexpensive because it is self-powered and generates compressed air through the supination motion of the user’s forearm instead of an external compressor, which is essential for conventional pneumatic systems. Stable flexible grasping of the target object was achieved by driving a five-finger hand using this system.

Development of a Five-Fingered Hand with Flexible Skin including Nerve Lines for Tool Use

Development of a Five-Fingered Hand with Flexible Skin including Nerve Lines for Tool Use

Normal and five-fingered hand: comparative X-ray morphometry in the post-natal age.

Five-fingered hand (5-FH) with completely developed phalanges is a rare phenotype observed so far only in humans and characterised by three phalanges of the 1st ray. A long-lasting, debated question is if the missing element of the normal hand 1st ray is the metacarpal or the phalanx. In this study, comparative X-rays morphometry of long bones in normal and 5-FH is carried out with the aim to face this question through homology analysis of long bone segments in the transverse and longitudinal line of normal hand and 5-FH. In the normal hand X-rays (n =20) and in a 5-FH X-rays series (n = 9) the relative length of each segment on the ray total length and the index of growth rate (IGR) were assessed. The calculation of the first parameter in normal hand bi-phalangeal thumb was carried out on the 3rd ray total length in the same hand. The parameters of relative length and the proximal/distal growth rate asymmetry in the post-natal period (assessed through the IGR) confirmed in 5-FH the homology of all the five segment on the transverse line. In the normal control hand, the relative length assessment methodology was biased by the missing segment of the thumb, therefore, the reference to the 3rd ray total length in the same hand (instead of the 1st), allowed the homology analysis of the thumb metacarpal and 1st phalanx with the lateral segments (2nd-5th ray) of the same hand. The 5-FH analysis was used to choose the more appropriate reference ray for the normal hand group. The comparative analysis of relative lengths and IGRs in the two groups suggested homology of the (anatomical) 1st metacarpal with the 2nd-5th proximal phalanges in the same hand and that of the (anatomical) 1st proximal phalanx with the 2nd-5th mid phalanges. These data suggest that the missing segment of the normal hand thumb is the metacarpal.

SMA micro-hand implemented in small robot for generating gestures

Research on robots that can be used for communication with humans has become popular in recent years. Communication robots should ideally be as small as an infant in order to reduce the user’s feeling of threat. In addition, non-verbal communication (such as gestures) is also important in facilitating smooth interactions between humans and robots. There are currently a few communication robots that are small sized and can generate hand gestures. In this paper, we propose a small robot hand, which is optimized for gesture communication by using a shape memory alloy (SMA). The SMA employed is a Ti–Ni alloy, which is used as an actuator. The SMA shrinks when it transforms into the austenite phase at temperatures higher than the transformation temperature. When it is in the martensitic phase at a lower temperature, it is expanded by an external force. Each finger of the robot hand is driven by an individual SMA wire. The specifications of the small robot including the hand size, operation angles in each finger joint, response times and power consumption were determined according to the human finger and existing small communication robots. These required specifications have been fulfilled by carefully designing the geometry and heating/cooling power control. A questionnaire-based survey was also conducted with a robot hand. The five-finger hand was successfully shown to generate recognizable symbolic gestures.

Novel design method for multi-configuration dexterous hand based on a gesture primitives analysis

Purpose This paper aims to propose a novel method based on a gesture primitives analysis of human daily grasping tasks for designing dexterous hands with various grasping and in-hand manipulation abilities, which simplifies the complex and redundant humanoid five-finger hand system. Design/methodology/approach First, the authors developed the fingers and the joint configuration with a series of gesture primitives configurations and the modular virtual finger scheme, refined from the daily work gesture library by principal component analysis. Then, the authors optimized the joint degree-of-freedom configuration with the bionic design analysis of the anatomy, and the authors optimized the dexterity workspace. Furthermore, the adaptive fingertip and routing structure were designed based on the dexterous manipulation theory. Finally, the effectiveness of the design method was experimentally validated. Findings A novel lightweight three-finger and nine-degree-of-freedom dexterous hand with force/position perception was designed. The proposed routing structure was shown to have the capability of mapping the relationship between the joint space and actuator space. The adaptive fingertip with an embedded force sensor can effectively increase the robustness of the grasping operation. Moreover, the dexterous hand can grasp various objects in different configurations and perform in-hand manipulation dexterously. Originality/value The dexterous hand design developed in this study is less complex and performs better in dexterous manipulation than previous designs.

A Soft Five-Fingered Hand Actuated by Shape Memory Alloy Wires: Design, Manufacturing, and Evaluation.

This work presents a novel five-fingered soft hand prototype actuated by Shape Memory Alloy (SMA) wires. The use of thin (100 μm diameter) SMA wire actuators, in conjunction with an entirely 3D printed hand skeleton, guarantees an overall lightweight and flexible structure capable of silent motion. To enable high forces with sufficiently high actuation speed at each fingertip, bundles of welded actuated SMA wires are used. In order to increase the compliance of each finger, flexible joints from superelastic SMA wires are inserted between each phalanx. The resulting system is a versatile hand prototype having intrinsically elastic fingers, which is capable to grasp several types of objects with a considerable force. The paper starts with the description of the finger hand design, along with practical considerations for the optimal placement of the superelastic SMA in the soft joint. The maximum achievable displacement of each finger phalanx is measured together with the phalanxes dynamic responsiveness at different power stimuli. Several force measurement are also realized at each finger phalanx. The versatility of the prototype is finally demonstrated by presenting several possible hand configurations while handling objects with different sizes and shapes.

Developing the knowledge of number digits in a child-like robot

Number knowledge can be boosted initially by embodied strategies such as the use of fingers. This Article explores the perceptual process of grounding number symbols in artificial agents, particularly the iCub robot—a child-like humanoid with fully functional, five-fingered hands. It studies the application of convolutional neural network models in the context of cognitive developmental robotics, where the training information is likely to be gradually acquired while operating, rather than being abundant and fully available as in many machine learning scenarios. The experimental analyses show increased efficiency of the training and similarities with studies in developmental psychology. Indeed, the proprioceptive information from the robot hands can improve accuracy in the recognition of spoken digits by supporting a quicker creation of a uniform number line. In conclusion, these findings reveal a novel way for the humanization of artificial training strategies, where the embodiment can make the robot’s learning more efficient and understandable for humans. Number processing is linked to bodily systems, especially finger movements. The authors apply convolutional neural network models in the context of cognitive developmental robotics. They show that proprioceptive information in the child-like robot iCub improves accuracy and recognition of spoken digits.

Synergy-Based Control of Underactuated Anthropomorphic Hands

In this paper, a grasping control strategy for an anthropomorphic robotic hand in a synergy-based framework is designed. The goal is to achieve a human-like behavior and robustness with respect to detailed information on objects shape and size. By adapting to underactuated kinematics a well-aimed method for human grasps mapping, the synergies subspace is computed. The designed control strategy allows the hand to adapt to object contours by means of coordinated fingers motion in the synergies subspace, and it is composed of a feedforward and two corrective terms to generate fingertip reference positions. The feedforward term is obtained by choosing, among the configurations contained in the set of grasps used for synergies computation, the one that is closest to the target grasp. This term ensures a suitable preshaping of the hand in the synergies subspace on the basis of object and grasp features. On the other hand, in order to adapt the grasp to the object, a weighted sum of two corrective terms is computed using the state of the motors as the feedback of the control law. The first term is designed to generate the closure of the hand towards the object. The second term is designed to optimize a grasp quality index based on force closure property. Moreover, exploiting the motor current feedback, soft synergies are implemented realizing compliance at the contact. The experiments conducted on the underactuated SCHUNK five-finger hand demonstrate the effectiveness of the method.

Key technologies of TianGong-2 robotic hand and its on-orbit experiments

With the development of robotics in recent years, space robotic manipulators have become a research focus on space technologies. In the TianGong-2 (TG-2) spacelab mission, a human-robot collaborative on-orbit servicing experiment was planned as one of the three key tasks. The central component of this task is the TG-2 robotic manipulator, which is a multisensory in-vehicle space robot with multiple control modes, including a 6-DOF robotic arm, a five-fingered humanoid hand, hand-eye and global cameras, and on-orbit human-machine interfaces(space mouse and cyber glove). The design purpose of TG-2 robotic task is to complete various prototypical experiments under micro-g environment to validate key technologies of space robots and on-orbit human-robot collaboration and gain experience and experimental data about robotic on-orbit servicing by assisting or cooperating with human astronauts. A variable time-scale motion plan method, which could adjusts the trajectories of the robot to reduce or eliminate the collision force between the robot collide with the environment, is developed for safe human-robot collaboration. The five-fingered hand grasp control is based on an approach coined as “coordinated grasp control based object Cartesian stiffness” for the adaptation of external forces and robust grasp. To solve the kinematic mapping from cyber glove commands to five-fingered robotic hand, a fingertip-position-based method is proposed to acquire precise solutions. The TG-2 robotic manipulator was launched to space in Sep. 15, 2016. From Oct. 27 to Nov. 13, 2016, all the planned experiments, including dynamic parameter identification, grasping floating objects and prototypical on-orbit servicing, were carried out successfully under the supervision and assistance of the two astronauts, laying foundations for the future applications of space robots.

F3Hand: A Five-Fingered Prosthetic Hand Driven with Curved Pneumatic Artificial Muscles.

Recently, many five-fingered prosthetic hands have been commercialized. However, most five-fingered prosthetic hands have heavyweight problems. In addition, their fingers with high rigidity are difficult to fit the object to be grasped. This paper reports a five-fingered prosthetic hand driven with curved pneumatic artificial muscles. By using the curved pneumatic artificial muscles as a skeleton and an actuator of the finger, flexible grasps and natural motions are achieved. Its weight of 255 g is less than one-third of the conventional fivefingered prosthetic hand. An evaluation using SHAP demonstrated that an amputee was able to operate various abstract objects.

Implementation of electroencephalography controlled prosthetic hand

The purpose of brain machine interface (BMI) is to provide a communication path between brain signals and external devices. Use of brain signals for restoring function of impaired body parts using scientific methods require brain machine interface. This article presents BMI to control five-fingered prosthetic hand using the electroencephalography (EEG) signals. The core objective of the system is to develop a control system that will be able to communicate with the brain thoughts. EEG signals captured from the human scalp are used as information carrier for brain control interface (BCI) system. This research article discusses the development of a system to assist disable persons using EEG based signals.

Development of Five-fingered Hand with Wide Range of Thumb Using Combination of Machined Springs and Variable Stiffness Joints

Development of Five-fingered Hand with Wide Range of Thumb Using Combination of Machined Springs and Variable Stiffness Joints

The evolution of the manus of early theropod dinosaurs is characterized by high inter- and intraspecific variation.

The origin of the avian hand, with its reduced and fused carpals and digits, from the five‐fingered hands and complex wrists of early dinosaurs represents one of the major transformations of manus morphology among tetrapods. Much attention has been directed to the later part of this transition, from four‐ to three‐fingered taxa. However, earlier anatomical changes may have influenced these later modifications, possibly paving the way for a later frameshift in digit identities. We investigate the five‐ to four‐fingered transition among early dinosaurs, along with changes in carpus morphology. New three‐dimensional reconstructions from computed tomography data of the manus of the Triassic and Early Jurassic theropod dinosaurs Coelophysis bauri and Megapnosaurus rhodesiensis are described and compared intra‐ and interspecifically. Several novel findings emerge from these reconstructions and comparisons, including the first evidence of an ossified centrale and a free intermedium in some C. bauri specimens, as well as confirmation of the presence of a vestigial fifth metacarpal in this taxon. Additionally, a specimen of C. bauri and an unnamed coelophysoid from the Upper Triassic Hayden Quarry, New Mexico, are to our knowledge the only theropods (other than alvarezsaurs and birds) in which all of the distal carpals are completely fused together into a single unit. Several differences between the manus of C. bauri and M. rhodesiensis are also identified. We review the evolution of the archosauromorph manus more broadly in light of these new data, and caution against incorporating carpal characters in phylogenetic analyses of fine‐scale relationships of Archosauromorpha, in light of the high degree of observed polymorphism in taxa for which large sample sizes are available, such as the theropod Coelophysis and the sauropodomorph Plateosaurus. We also find that the reduction of the carpus and ultimate loss of the fourth and fifth digits among early dinosaurs did not proceed in a neat, stepwise fashion, but was characterized by multiple losses and possible gains of carpals, metacarpals and phalanges. Taken together, the high degree of intra‐ and interspecific variability in the number and identities of carpals, and the state of reduction of the fourth and fifth digits suggest the presence of a ‘zone of developmental variability’ in early dinosaur manus evolution, from which novel avian‐like morphologies eventually emerged and became channelized among later theropod clades.

Phase estimation for fast action recognition and trajectory generation in human–robot collaboration

This paper proposes a method to achieve fast and fluid human–robot interaction by estimating the progress of the movement of the human. The method allows the progress, also referred to as the phase of the movement, to be estimated even when observations of the human are partial and occluded; a problem typically found when using motion capture systems in cluttered environments. By leveraging on the framework of Interaction Probabilistic Movement Primitives, phase estimation makes it possible to classify the human action, and to generate a corresponding robot trajectory before the human finishes his/her movement. The method is therefore suited for semi-autonomous robots acting as assistants and coworkers. Since observations may be sparse, our method is based on computing the probability of different phase candidates to find the phase that best aligns the Interaction Probabilistic Movement Primitives with the current observations. The method is fundamentally different from approaches based on Dynamic Time Warping that must rely on a consistent stream of measurements at runtime. The resulting framework can achieve phase estimation, action recognition and robot trajectory coordination using a single probabilistic representation. We evaluated the method using a seven-degree-of-freedom lightweight robot arm equipped with a five-finger hand in single and multi-task collaborative experiments. We compare the accuracy achieved by phase estimation with our previous method based on dynamic time warping.

筋骨格ヒューマノイドのための切削ばねによる柔軟関節を備えた五指ハンドの開発と自己身体負荷保持動作の実現

Human can support their body not only in the foot but also by hand, so that they can dangle a bar and so on. But most humanoid robots support their body only in the foot and they use their hand just to manipulate objects because of the weakness of their hands. Strong hands enable humanoid robots to act in broader scene. Therefore, we developed the new life-size five-fingered hand that can support the body of life-size humanoid robot. It is tendon-driven and underactuated hand and actuators in forearms produce high gripping force. Because this hand has soft joints consisting of machined springs, it has both structural strength and impact resistance. We installed the hand to musculoskeletal humanoid “Kengoro” and achieved two self-weight supporting motions, push-up motion and dangling motion.

Haptic Interface for Displaying Softness at Multiple Fingers: Combining a Side-Faced-Type Multifingered Haptic Interface Robot and Improved Softness-Display Devices

We describe the development of a haptic interface that can present the sensation of softness to multiple fingers. Human hands experience the sensation of softness when touching a yielding object like a human body. In virtual training systems for medical procedures such as palpation, how to display softness at multiple fingertips is an essential and demanding problem. To solve it, we develop a softness-display device using a flexible sheet and realize a haptic interface able to present softness sensations at multiple fingers. The haptic interface combines the newly developed device and our previously developed multifingered haptic interface robot, which consists of a five-fingered hand and an arm. We then carry out several experiments and demonstrate the validity of the developed haptic interface.

A Rare Syndrome of Five Finger Hands and Polydactyly of the Feet: A Case Report

Combination of multiple congenital anomalies in the upper and lower limbs is an uncommon clinical presentation. Al-Qattan et al have indicated that the presence of double ulna is not mandatory to make the diagnosis of mirror hand. The absence of the thumb and the presence of the five-fingered hand and hypoplastic radius might be considered as an atypical mirror hand anomaly [1]. There are several definitions for the mirror foot anomaly including a foot with mirror image polydactyly, a foot with supernumerary rays with the characteristics of the post-axial toes situated medial to the first ray (preaxialy), and mirror duplication of the all skeletal structures on the tibial aspect of the foot [2]. This report presents a rare syndrome in a 22-year-old man who presented with five finger hands and polydactyly of his feet. The radius and the radial carpal bones were hypoplastic on both sides. The anomalies might be a rare syndrome of atypical mirror hands and mirror feet.