Fingerprint-inspired surface texture for the enhanced tip pinch performance of a soft robotic hand in lubricated conditions

The core capabilities of soft grippers/soft robotic hands are grasping and manipulation.At present,most related research often improves the grasping and manipulation performance by structural design.When soft grippers rely on compressive force and friction to achieve grasping,the influence of the surface microstructure is also significant.Three types of fingerprint-inspired textures with relatively regular patterns were prepared on a silicone rubber surface via mold casting by imitating the three basic shapes of fingerprint patterns(i.e.,whorls,loops,and arches).Tribological experiments and tip pinch tests were performed using fingerprint-like silicone rubber films rubbing against glass in dry and lubricated conditions to examine their performance.In addition to the textured surface,a smooth silicone rubber surface was used as a control.The results indicated that the coefficient of friction(COF)of the smooth surface was much higher than that of films with fingerprint-like textures in dry and water-lubricated conditions.The surface with fingerprint-inspired textures achieved a higher COF in oil-lubricated conditions.Adding the fingerprint-like films to the soft robotic fingers improved the tip pinch gripping performance of the soft robotic hand in lubricated conditions.This study demonstrated that the surface texture design provided an effective method for regulating the grasping capability of humanoid robotic hands.

功率控制误差对CDMA蜂窝系统性能的影响

通过将接收信号功率描述为对数正态分布的随机变量，其标准方差表示功率控制的误差，分析了在ＣＤＭＡ蜂窝系统中，功率控制误差、软切换方案及话音激活技术对ＣＤＭＡ蜂窝系统性能的影响．计算表明，采用精确的功率控制技术。

CDMA中切换参数的设置及其对系统的影响

在简述蜂窝移动通信切换过程的基础上 ,重点讨论了 CDMA(码分多址联接 )系统软切换的参数设置 ,并借助模拟软件

模糊理论在CDMA软切换中的应用

传统软切换一般采用常数阈值,若设置过小,则将占用过多的业务信道;设置过大,则软切换减少,掉话率增加。基于此,本文研究了模糊理论在码分多址移动通信系统软切换阈值中的应用及仿真技术。采用模糊软切换,通过剩余业务信道数量(CHrm)及与移动台连接的基站数量(noBS)输入获得软切换阈值,提出了输入T_DROP、CHrm,输出noBS采用三角形隶属函数及利用加权平均公式的解模糊方案。仿真结果表明,模糊软切换比传统软切换更灵活,它依靠系统环境动态地给出软切换阈值,降低了系统的呼叫阻塞率,提高了资源效率。

Machine Learning-Based Multi-Modal Information Perception for Soft Robotic Hands

This paper focuses on multi-modal Information Perception(IP)for Soft Robotic Hands(SRHs)using Machine Learning(ML)algorithms.A flexible Optical Fiber-based Curvature Sensor(OFCS)is fabricated,consisting of a Light-Emitting Diode(LED),photosensitive detector,and optical fiber.Bending the roughened optical fiber generates lower light intensity,which reflecting the curvature of the soft finger.Together with the curvature and pressure information,multi-modal IP is performed to improve the recognition accuracy.Recognitions of gesture,object shape,size,and weight are implemented with multiple ML approaches,including the Supervised Learning Algorithms(SLAs)of K-Nearest Neighbor(KNN),Support Vector Machine(SVM),Logistic Regression(LR),and the unSupervised Learning Algorithm(un-SLA)of K-Means Clustering(KMC).Moreover,Optical Sensor Information(OSI),Pressure Sensor Information(PSI),and Double-Sensor Information(DSI)are adopted to compare the recognition accuracies.The experiment results demonstrate that the proposed sensors and recognition approaches are feasible and effective.The recognition accuracies obtained using the above ML algorithms and three modes of sensor information are higer than 85 percent for almost all combinations.Moreover,DSI is more accurate when compared to single modal sensor information and the KNN algorithm with a DSI outperforms the other combinations in recognition accuracy.

Synergistic control of soft robotic hands for human-like grasp postures

Although significant advances in the design of soft robotic hands have been made to mimic the structure of the human hands,there are great challenges to control them for coordinated and human-like postures.Based on the principle of postural synergies in the human hand,we present a synergistic approach for coordinated control of a soft robotic hand to replicate the human-like grasp postures.To this end,we firstly develop a kinematic model to describe the control variables and the various postures of the soft robotic hand.Based on the postural synergies,we use the developed model and Principal Component Analysis(PCA)method to describe the various postures of the soft robotic hand in a low-dimensional space formed by the synergies of actuator motions.Therefore,the coordinates of these synergies can be used as low-dimensional control inputs for the soft robotic hand with a higher-dimensional postural space.Finally,we establish an experimental platform on a customized soft robotic hand with6 pneumatical actuators to verify the effectiveness of the development.Experimental results demonstrate that with only a 2-dimensional control input,the soft robotic hand can reliably replicate 30 grasp postures in the Feix taxonomy of the human hand.

A Smart and Hybrid Composite Finger with Biomimetic Tapping Motion for Soft Prosthetic Hand

This paper introduces the design and fabrication of a smart and Hybrid Composite Finger(HCF)to achieve finger-like motions,such as holding and tapping motions.Bionic research on tapping motion of the index finger was conducted to obtain its structural and tapping parameters.The HCF,actuated by Shape Memory Alloy(SMA)wires,possesses a hybrid structure which is composed of a rigid structure to be its metacarpal part and a deformable structure to produce bending movement just like the function of the finger.Owing to an adhesive bonding technology,the HCF was fabricated with a composite structure which is reliable under impulsive responses,and had a worklife of more than 630000 times.A bending model was built by synthesizing the phase transformation dynamic model of the SMA wires and quasi-static analysis of the HCF.Structural optimization of the HCF was conducted by synthesizing the bending model together with experimental analyses.To produce a holding motion like as the finger,a holding heating strategy was proposed to adaptively heat the HCF to keep holding state based on the resistance feedback of SMA wires and a Proportion Differentiation(PD)algorithm.Besides,we used an impulsive heating method to heat the HCF to produce a high fidelity tapping motion with a maximum tapping force(6.83 N)at a response time(43 ms)which considerably coincided with those(about 5.8 N,45 ms)from tapping bionics of the index finger.Finally,a soft prosthetic hand system which had a hand-like appearance was manufactured based on the HCFs and several tests like as anthropomorphic gesture motions and human-like tapping motions to tap a keyboard were conducted to prove potential application of the HCF.

蜂窝移动通信系统中软硬切换衰落余量分析

基于具有对数正态阴影衰落的两小区系统模型,分析了采用不同切换技术时,为满足一定的中断率系统所要求的衰落余量,并给出了详细的推导过程。仿真结果表明,在要求中断概率相同的情况下,具有有限滞后电平的硬切换所要求的衰落余量大于软切换所要求的衰落余量而小于孤立小区硬切换所要求的衰落余量,并且滞后电平越小,所需要的衰落余量就越小。

Design, kinematic modeling and evaluation of a novel soft prosthetic hand with abduction joints

This paper presents a novel tendon-driven soft prosthetic hand with 5 fingers and 9 independent actuators.A special notched structure was used as the finger joint,which brings adequate compliance to grasping.The soft finger has two kinds of vertically arranged joints that can produce flexion/extension and abduction/adduction motions under tension and release,enabling a three-dimensional workspace of the finger and improving the dexterity of the hand.The design and manufacture of the finger and soft hand are described in detail.An openloop kinematic model based on piecewise constant curvature of the finger was established and verified experimentally.The results show that the model could precisely predict finger movement.The slip resistance of the soft hand was tested,and the capacity to grasp objects was evaluated based on power grasp and precision grasp.With abduction joints,the proposed hand can perform various gestures and in-hand manipulations,which indicate high dexterity.This work provides a way to realize high dexterity for soft prosthetic hands.

A totally laparoscopic peritoneal free flap for reconstruction of hand

Management of defects on the hand and foot with exposed tendons remains a major challenge for plastic surgeons. Here, we present a case of hand reconstruction with a totally laparoscopic peritoneal flap. The anterior rectus sheath was preserved in situ. The peritoneal free flap supplied by peritoneal branches of the deep inferior epigastric artery was retrieved by laparoscopy to cover the soft tissue defect of the hand. The defect of the dorsal hand was 17 cm × 12 cm. The peritoneal flap measuring 22 cm × 15 cm survived completely without any complications. A following split-thickness skin graft offered the suc- cessful wound closure. Motor and sensory function improved gradually within the first year follow-up. The totally laparoscopic peritoneal free flap is a good choice for reconstruction of the soft tissue de- fects accompanied by exposed tendons on the hand and foot.

Modeling and Analysis of Soft Bionic Fingers for Contact State Estimation

Contact state estimation is significant for evaluating grasp stability of bionic hands,especially in unknown environments or without visual/tactile feedback.It still remains challenging,particularly for soft bionic hands without integrating complicated external sensors on soft fingers.Focusing on this issue,a proprioceptive-sensing-based systematic solution is proposed to estimate the contact state of soft bionic fingers in a single grasp.A kinematic model for soft fingers is first developed to capture the joint rotation angles and tendon displacement.A kinetostatic model is further built to estimate the contact force when soft fingers come in contact with objects.On this basis,a system stiffness model for soft fingers during preshaping and initial contact with objects is proposed to perceive the contact state.Moreover,an instantaneous stiffness model for soft fingers when initial contact occurs is developed for estimating the contact position on certain phalanges,especially the contact position along the distal phalange.The proposed proprioceptive-sensing-based approach is the first application in soft fingers without integrating complicated external sensors,which makes them concise and practical.Experiments are carried out to demonstrate the effectiveness and efficiency of our proposal.