DESIGN OF A NOVEL DEXTEROUS ROBOT HAND

In the robotic community more and more hands are developed. Based on theexperience of HIT Hand and DLR Hand II, a smaller and easier manufactured dexterous robot hand withmultisen-sory function and high integration is jointly developed. The prototype of the hand issuccessfully built. It has 4 fingers in total 13-DOFs (degree of freedom). Each finger has 3-DOFsand 4 joints, the last 2 joints are mechanically coupled by means of four-bar linkage mechanism. Italso has an additional DOF to realize motion of the thumb relative to the palm. The fingertip forcecan reach up to 10 N. Full integration of mechanical body, actuation system, multisensory system andelectronics is a significant feature. DSP based control system is implemented in PCI busarchitecture and the serial communication between the hand and DSP needs only 2 lines.

Design and modeling for a kind of humanoid dexterous hand with elastic palm

With dexterous hands, robots can improve the work scope and work ability significantly. As palms of the existing multi-hand robots are made of steel plates that have small contact area, the robots cannot grab firmly. In this study, a new five-fingered dexterous robot hand is developed. Having flexible palm with 17 degree of freedoms （ DOFs）, the hand can grasp more stably and firm- ly. First, the forward kinematics and inverse kinematics of the fingers and the hand are calculated. Then, the connection between the force exerting on the end effectors and the torque exerting on the joint is set up, laying the foundation for the following control. Finally, through the analysis and sim- ulation of the position, velocity and acceleration, the trajectory planning has a better performance.

MANIPULATION KINEMATICS ON DEXTEROUS HANDS CONSIDERING PURE ROLLING CONTACTS AS PASSIVE JOINTS

The manipulation and constraint equations are established by considering the pure rolling motion in a dexterous hand as two passive joints. According to mapping relation among the motion of the system, the differential kinematics and mobility are studied. The minimal structure for realizing the task motion of the object is obtained, and the conditions for dexterous manipulation are presented. Finally, some rolling manipulations are used as examples to demonstrate the applicability of approach proposed.

Design and fabrication of a gecko-inspired surface for improving the grasping ability of a humanoid dexterous hand

Many studies have examined the design,fabrication and characteristics of gecko-inspired adhesives,but applied research on gecko-inspired surfaces in humanoid dexterous hands is relatively scarce.Here,a wedged slanted structure with a curved substrate suitable for humanoid dexterous fingers was designed and manufactured via ultraprecision machining and replica molding.The adhesion and friction properties of the wedged slanted structure show obvious anisotropic characteristics in the gripping and releasing directions,and the influence of structural parameters and motion parameters on the adhesion and friction was systematically studied.The humanoid dexterous fingers with gecko-inspired surfaces greatly increased the grasping force limit(increase to 4.02 times)based on the grasping of measuring cups with different volumes of water and improved the grasping stability based on the picking up of smooth steel balls of different diameters.This study shows that this process,based on ultraprecision machining and replica molding,is a green,high-efficiency,and low-cost method to fabricate large-area biomimetic surfaces that has potential applications in dexterous humanoid hands to improve grasping ability,stability and adaptability.

Anthropomorphic Control of a Dexterous Artificial Hand via Task Dependent Temporally Synchronized Synergies

Despite the recent influx of increasingly dexterous prostheses, there remains a lack of sufficiently intuitive control methods to fully utilize this dexterity. As a solution to this problem, a control framework is proposed which allows the control of an arbitrary number of Degrees of Freedom （DOF） through a single electromyogram （EMG） control input. Initially, the joint motions of nine test subjects were recorded while grasping and catching a cylinder. Inherent differences emerged depending upon whether the cylinder was grasped or caught. These data were used to form a distinct synergy for each task, described as the families of parametric functions of time that share a mutual time vector. These two Temporally Synchronized Synergies （TSS） were derived to reflect the task dependent control strategies adopted by the initial participants. These synergies were then mapped to a dexterous artificial hand that was subsequently controlled by two subjects with transradial amputations. The EMG signals from these subjects were used to replace the time vector shared by the synergies, enabling the subjects to perform both tasks with a dexterous artificial hand using only a single EMG input. After a ten minute training period, the subjects learned to use the dexterous artificial hand to grasp and catch the cylinder with 100.0% and 65.0% average success rates, respectively.

The Development of a Two-finger Dexterous Bionic Hand with Three Grasping Patterns-NWAFU Hand

Bionic inspiration from human thumb and index finger was the drive to design a high-performance two-finger dexterous hand.The size of each phalanx and the motion range of each joint in the human thumb and index finger were summarized,and the features of three grasping patterns were described in detail.Subsequently,a two-finger dexterous bionic hand with 6 Degrees of Freedom(DoFs)was developed.Both the mechanical thumb and index finger were made up of three rigid phalanx links and three mechanical rotation joints.Some grasp-release tests validated that the bionic hand can perform three grasping patterns:power grasp,precision pinch and lateral pinch.The grasping success rates were high under the following cases:(1)when power grasping was used to grasp a ring with external diameter 20 mm-140 mm,a cylinder with mass<500 g,or objects with cylinder,sphere or ellipsoid shape;(2)when the precision pinch was used to grasp thin or small objects;(3)when the lateral pinch was used to grasp low length-to-width ratio of objects.The work provided a method for developing two-fimger bionic hand with three grasping patterns,and further revealed the linkage between the difference in fimger structure and size and the hand manipulation dexterity.

Human-machine shared control:New avenue to dexterous prosthetic hand manipulation

At present,albeit the dexterous hand prostheses of multiple degrees of freedom(DOFs)have become prosperous on the market,the user’s demand on intuitively operating these devices have not been well addressed so that their acceptance rate is relatively low.The unintuitive control method and inadequate sensory feedback are frequently cited as the two barriers to the successful application of these dexterous products.Recently,driven by the wave of artificial intelligence(AI),a series of shared control methods have emerged,in which"bodily function"(myoelectric control)and"artificial intelligence"(local autonomy,computer vision,etc.)are tightly integrated,and provided a new conceptual solution for the intuitive operation of dexterous prostheses.In this paper,the background and development trends of this type of methods are described in detail,and the potential development directions and the key technologies that need breakthroughs are indicated.In practice,we instantiate this shared control strategy by proposing a new method combining simultaneous myoelectric control,multi-finger grasp autonomy,and augmented reality(AR)feedback together.This method"divides"the human sophisticated reach-and-grasp task into several subtasks,and then"conquers"them by using different strategies from either human or machine perspective.It is highly expected that the shared control methods with hybrid human-machine intelligence could address the control problem of dexterous prostheses.

Cortical activity in patients with high-functioning ischemic stroke during the Purdue Pegboard Test:insights into bimanual coordinated fine motor skills with functional near-infrared spectroscopy

After stroke,even high-functioning individuals may experience compromised bimanual coordination and fine motor dexterity,leading to reduced functional independence.Bilateral arm training has been proposed as a promising intervention to address these deficits.However,the neural basis of the impairment of functional fine motor skills and their relationship to bimanual coordination performance in stroke patients remains unclear,limiting the development of more targeted interventions.To address this gap,our study employed functional near-infrared spectroscopy to investigate cortical responses in patients after stroke as they perform functional tasks that engage fine motor control and coordination.Twenty-four high-functioning patients with ischemic stroke(7 women,17 men;mean age 64.75±10.84 years)participated in this cross-sectional observational study and completed four subtasks from the Purdue Pegboard Test,which measures unimanual and bimanual finger and hand dexterity.We found significant bilateral activation of the sensorimotor cortices during all Purdue Pegboard Test subtasks,with bimanual tasks inducing higher cortical activation than the assembly subtask.Importantly,patients with better bimanual coordination exhibited lower cortical activation during the other three Purdue Pegboard Test subtasks.Notably,the observed neural response patterns varied depending on the specific subtask.In the unaffected hand task,the differences were primarily observed in the ipsilesional hemisphere.In contrast,the bilateral sensorimotor cortices and the contralesional hemisphere played a more prominent role in the bimanual task and assembly task,respectively.While significant correlations were found between cortical activation and unimanual tasks,no significant correlations were observed with bimanual tasks.This study provides insights into the neural basis of bimanual coordination and fine motor skills in high-functioning patients after stroke,highlighting task-dependent neural responses.The findings also suggest that patients who exhibit better bimanual performance demonstrate more efficient cortical activation.Therefore,incorporating bilateral arm training in post-stroke rehabilitation is important for better outcomes.The combination of functional near-infrared spectroscopy with functional motor paradigms is valuable for assessing skills and developing targeted interventions in stroke rehabilitation.

An Adaptive Hand Exoskeleton for Teleoperation System

Teleoperation can assist people to complete various complex tasks in inaccessible or high-risk environments,in which a wearable hand exoskeleton is one of the key devices.Adequate adaptability would be available to enable the master hand exoskeleton to capture the motion of human fingers and reproduce the contact force between the slave hand and its object.This paper presents a novel finger exoskeleton based on the cascading four-link closed-loop kinematic chain.Each finger has an independent closed-loop kinematic chain,and the angle sensors are used to obtain the finger motion including the flexion/extension and the adduction/abduction.The cable tension is changed by the servo motor to transmit the contact force to the fingers in real time.Based on the finger exoskeleton,an adaptive hand exoskeleton is consequently developed.In addition,the hand exoskeleton is tested in a master-slave system.The experiment results show that the adaptive hand exoskeleton can be worn without any mechanical constraints,and the slave hand can follow the motions of each human finger.The accuracy and the real-time capability of the force reproduction are validated.The proposed adaptive hand exoskeleton can be employed as the master hand to remotely control the humanoid five-fingered dexterous slave hand,thus,enabling the teleoperation system to complete complex dexterous manipulation tasks.

利用热激子反向系间窜越的特征磁响应探测界面型OLED中的Dexter能量传递过程

基于界面激基复合物作为主体的主-客体型有机发光二极管(organic light emitting diodes,OLEDs)的外量子效率已经突破36%,但其主-客体间能量传递过程还有待深入研究.本文提出一种基于客体Rubrene热激子反向系间窜越(T_(2,Rub)→S_(1,Rub))的特征磁响应探测界面激基复合物型OLEDs中能量传递过程的实验策略.具体通过表征主、客体材料的光物理特性,证明了主-客体单重态激子间的F?rster共振能量传递过程;通过研究界面激基复合物型器件的磁电致发光响应曲线,可视化了主-客体三重态激子间的Dexter能量传递过程,且该过程有效发生对于器件电致发光具有不可忽视的促进作用.本研究不仅为探测OLEDs中Dexter能量传递过程提供切实可行的理论方法,还为进一步设计高性能热激子型OLEDs提供新的实验参考.

Driven by Dexterity:Vocational training plays a key role in rural revitalisation in China

Ying Chao,born in the 1990s in Jiaxing City of east China’s Zhejiang Province,is of the opinion that traditional agricultural methods cannot meet the demands of modern farming.He plans to change agricultural practices and follow the road of mechanisation after taking part in a one-year vocational training course on drones in Jiaxing Vocational and Technical College in 2021.In fact,more and more young people like Ying are applying digital technology and big data to agricultural production and rural development.And the government has laid out plans to encourage this transition.

Dy^(3+)-Tb^(3+)掺杂氟氧碲酸盐玻璃的光谱性能研究

实验采用高温熔融法制备了一系列Dy3+离子、Tb3+离子单掺或共掺氟氧碲酸盐玻璃样品.测试了不同摩尔含量的Dy3+离子和Tb3+离子的氟氧碲酸盐玻璃样品的密度,分析了紫外-可见透射光谱、激发光谱、发射光谱、发光衰减曲线,研究了不同摩尔含量的Dy3+离子和Tb3+离子的氟氧碲酸盐玻璃样品光谱性能及Dy3+离子到Tb3+离子能量传递机理.结果表明:Dy3+离子、Tb3+离子单掺或共掺氟氧碲酸盐玻璃样品的密度均大于5g·cm-3,最大可达6.09g·cm-3;Dy3+离子可以敏化Tb3+离子,促进其发光,但当Dy3+离子超过一定浓度后,会发生离子间浓度猝灭效应,Tb3+离子的发光反而降低.试验测得,Dy3+离子的最佳掺杂浓度为1.0mol%,此时,Tb3+离子掺杂浓度为6.0mol%,Tb3+离子发光效果最强.依据Dexter能量传输理论,并对Dy3+离子和Tb3+离子的能级图及能级间的跃迁进行分析,可知Dy3+离子和Tb3+离子间的能量传递方式为非辐射共振传递.

Dexter:一种超媒体参考模型

目前超媒体系统的应用领域变得越来越广泛,但是这些超媒体系统在设计和实现的过程中往往出现了术语不统一和系统描述方法大相径庭的问题,因此Dexter模型的诞生为未来超媒体系统的设计起着参考和指导作用。本文首先对国内容易引起混淆且使用混乱的三个概念——超文本、多媒体和超媒体——予以明确的定义,然后详细介绍Dexter模型的三层结构,最后总结了Dexter模型的成功与不足之处。

一个适于CAI课件设计的超文本知识库结构模型

目前在CAI课件设计中最受推崇的知识组织形式就是超文本结构。本文在Dexter超文本参考模型的基础上,针对CAI课件设计中的特殊需要,提出一种超文本知识库结构模型。

掺磷光材料有机电致发光器件的能量传递

将高量子效率的磷光材料fac-tris-2-phenylpyridine iri dium(Ⅲ)(Ir(ppy)_3)按不同的比例掺杂到具有载流子传输能力的主体材料poly(N-vinylcarbazole)(PVK)中作为发光层制备磷光电致发光器件。通过对器件发光机制的研究,发现光致发光过程中起主导作用的是Foster能量转移机制;而在电致发光过程中,器件的发光性能受Dexter能量转移和电荷陷获2种能量传递形式的影响。器件的I-V-L特性表明:Ir(ppy)_3的掺杂比例为5%时,器件的光功率效率最大,能量转移最充分。

掺铒PLZT电光陶瓷发光特性

测量并分析了Er3+∶PLZT电光陶瓷的吸收光谱和上转换光谱,利用Dexter理论和速率方程理论研究了该材料的发光特性。通过Dexter理论计算得到4I13/2+4I13/2→4I9/2+4I15/2(ET1)和4I11/2+4I11/2→4I15/2+4F7/2(ET2)能量传递过程的交叉驰豫几率分别为2.06×105s-1和1.61×105s-1。以此为基础,结合Er3+跃迁的动力学模型,利用速率方程讨论了交叉驰豫过程对4I13/2,4I11/2,4I9/2能级上离子数的影响。通过分析可知,ET1和ET2交叉驰豫过程将会使4I13/2能级粒子数大幅度减少,不利于1550 nm发光,而对800 nm的发光起到较大的促进作用。

超媒体模型中时态行为研究

实现超媒体系统的关键之一是提供对多媒体同步的支持，文中在Ｄｅｘｔｅｒ参考模型的基础上，进行了合理的扩充以描述和存储多媒体数据的时态参数，并给出了相应的展示算法．

Vision-Based Action Control System of a Multi-Finger Mechanical Gripper

A study about the action control of a dexterous mechanical gripper based on stereo-vision system was proposed. The vision-based system was used to replace the data-glove for gesture measurement. The stereo vision theory was applied to calculate the 3D information of the hand gesture. The information was used to generate the grasping action parameters of a 3-finger dexterous mechanical gripper. Combined with a force feedback device, a closed control loop could be constructed. The test for the precision of the algorithms and action control simulation result were shown in the paper.

人类天然低分子抑瘤物净化自体骨髓移植治疗急性白血病

我们用人胎儿肝脏中分离出一种天然低分子物质，暂称人类天然低分子抑瘤物(Lmw-Nts)为净化剂，以Dexter骨髓细胞体外液体培养体系为基础，体外净化自血病细胞后自体骨髓移植治疗12例急性自血病。男性7例，女性5例。年龄10-43岁；ALL4例，ANLL8例，CR；6例，CR2 2例，CR至移植中位时间5个月。采集自体骨髓血(NC>2．5×10^3/kg)，经羧甲基淀粉沉降红细胞，离心洗涤后骨髓有核细胞加入体外净化培养体系7天，