HIT prosthetic hand based on tendon-driven mechanism

An underactuated finger structure actuated by tendon-driven system is presented.Kinematics and static analysis of the finger is done,and the results indicate that the prosthetic finger structure is effective and feasible.Based on the design of finger,a prosthetic hand is designed.The hand is composed of 5 independent fingers and it looks more like humanoid.Its size is about 85% of an adult＇s hand and weights about 350 g.Except the thumb finger,each finger is actuated by one DC motor,gear head and a tendon,and has three curling/extension joints.The thumb finger which is different from other existing prostheses is a novel design scheme.The thumb finger has four joints including three curling/extension joints and a joint which is used to realize the motion of the thumb related to the palm,and these joints are also driven by one DC motor,harmonic drive and a tendon.The underactuation and adaptive curling/extension motion of the finger are realized by joint torsion springs.A high-powered chip of digital signal processing （DSP） is the main part of the electrical system which is used for the motors control,data collection,communication with external controlling source,and so on.To improve the reliability of the hand,structures and sensors are designed and made as simply as possible.The hand has strong manipulation capabilities that have been verified by finger motion and grasping tests and it can satisfy the daily operational needs and psychological needs of deformities.     

Liquid droplet movement on horizontal surface with gradient surface energy

A surface with gradient surface energy was fabricated on a silicon wafer by using the chemical vapor deposition (CVD) technology with the dodecyltrichlorosilane (C12H25Cl3Si) vapor which was adsorbed chemically on the surface of the silicon wafer to form a self-assemble monolayer (ASM) and thus a gradient profile of wettability. The microscopic contours of the gradient surface were measured with Seiko SPA400 atom force microscope (AFM). And the surface wettability profile was characterized by the sessile drop method, measuring the contact angle of fine water droplets that lay on the gradient surface, to represent the distribution of the surface energy on the surface. Using a high-speed video imaging system, the motion of water droplet on the horizontal gradient surface was visualized and the transient velocity was measured under ambient condition. The experimental results show that the liquid droplets can be driven to move from hydrophobic side to hydrophilic side on the horizontal gradient surface and the velocity of droplet can reach up to 40 mm/s. In addition, the motion of the water droplet can be generally divided into two stages: an acceleration stage and a deceleration stage. The droplet presents a squirming movement on the surface with a lower peak velocity and a larger extent of deceleration motion. And the static advancing contact angle of the droplet is obviously larger than the dynamic advancing contact angle on the gradient energy surface.     

Modeling study on fluid flow and inclusion motion in 6-strand bloom caster tundishes

The behavior of fluid flow and particle motion in a 6-strand bloom caster tundish was investigated by a water model and numerical simulation. Compared with a device without flow control, the tundish with flow control has an important effect on the fluid flow pattern and inclusion removal. It is revealed that by non-isothermal process, which is real production condition, the fluid flow in tundish shows a strong buoyancy pattern, which drives particles to move upwards. The particle removal was quantitatively studied by mathematical and physical simulations.     

Cartesian impedance control of dexterous robot hand

Presents a novel compliant motion control for a robot hand using the Cartesian impedance approach based on fingertip force measurements. The fingertip can accurately track desired motion in free space and appear as mechanical impedance in constrained space. In the position based impedance control strategy, any switching mode in contact transition phase is not needed. The impedance parameters can be adjusted in a certain range according to various tasks. In this paper, the analysis of the finger‘s kinematics and dynamics is given. Experimental results have shown the effectiveness of this control strategy.     

The design and implementation of virtual hand grasp behavior process in virtual assembly

Virtual hand is an important medium for implementation of human-computer interaction in the process of virtual assembly. And the comparability between the action of virtual hand and real man-hand has always been regarded as one of the important criteria to judge whether the virtual environment has the property of immersion. On the basis of analyzing the relative position,posture,and motion behavior relationship between virtual hand and the object to be operated during virtual assembly,this paper proposed an implementation method of combining grasp index with collision detecting technology for identifying grasp action of virtual hand. The method is to identify grasp/quit using grasp index and to implement joint angle adjustment through simulation cyclic iteration and joint angle interpolation calculation. Although some traditional method identifying the grasp action on the basis of the shape of the object is operated,the simulation result getting from virtual environment created by EON STUDIO shows that it has good features of serviceability and fidelity to realize operation control of virtual hand.     

Trajectory planning and tracking control for underactuated unmanned surface vessels简

The trajectory planning and tracking control for an underactuated unmanned surface vessel（USV） were addressed.The reference trajectory was generated by a virtual USV,and the error equation of trajectory tracking for underactuated USV was obtained,which transformed the tracking and stabilization problem of underactuated USV into the stabilization problem of the trajectory tracking error equation.A nonlinear state feedback controller was proposed based on backstepping technique and Lyapunov＇s direct method.By means of Lyapunov analysis,it is proved that the proposed controller ensures that the solutions of closed loop system have the ultimate boundedness property.Numerical simulation results are presented to validate the effectiveness and robustness of the proposed controller.     

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.     

Inter-limb and intra-limb coordination control of quadruped robots

To realize the coordinated and stable rhythmic motion of quadruped robots (QRs), the locomotion control method of QRs based on central pattern generator (CPG) was explored. In traditional control strategies based on CPG, few CPG models care about the intra-limb coordination of QRs, and the durations of stance phase and swing phase are always equal. In view of these deficiencies, a new and simpler multi-joint coordinated control method for both inter-limb and intra-limb was proposed in this paper. A layered CPG control network to realize the locomotion control of QRs was constructed by using modified Hopf oscillators. The coupled relationships among hip joints of all limbs and between hip joint and knee joint within a limb were established. Using the co-simulation method of ADAMS and MATLAB/Simulink, various gait simulation experiments were carried out and the effectiveness of the designed control network was tested. Simulation results show that the proposed control method is effective for QRs and can meet the control requirements of QRs' gaits with different duty factors.     

Slope Terrain Locomotion Control of a Quadruped Robot Based on Biological Reflex CPG Model

Inspired by the neuronal principles underlying the tetrapod locomotion,this paper proposed a biomimetic vestibular reflex central pattern generator(CPG) model to improve motion performance and terrain adaptive ability of a quadruped robot in complex situations,which is on the basis of central pattern generator (CPG) model constructed by modified Hopf oscillators.The presented reflex model was modified in the light of the particular joint configuration of the quadruped robot and the trot gait pattern.Focusing on slop locomotion of the quadruped robot with trot gaits,the cosimulations of the ADAMS virtual prototype,CPG mathematical expressions with vestibular reflex and Simulink control model were conducted.The simulation results demonstrated that the presented CPG controller with vestibular reflex was more efficient and stable for the quadruped robot trotting on slopes,compared with the different trotting control models.     

The fabrication of microstructure surface of super-hydrophobic coating by surface gelation technology

The microstructured surface of materials were fabricated by a two-step acid-base catalyzed sol-gel process. In fluorinated polymer with PTFE doping, the well-proportioned composite sols were prepared using sol-gel processing under the hydrochloric acid and deficiency of water conditions. After the substrate was coated by composite sols, and the gelation treatment on the surface of composite coating, the micrometer-scale and nanometer-scale hierarchical structures were formed in surface layer of material. XPS and TEM technologies were employed to identify that the gelation occurs just on the surface of composite coating. The morphology of coating surface was observed by SEM and AFM technologies. The microstructured surface of material can be fabricated using this inexpensive and easily controlled method on low surface energy resin materials, the super-hydrophobic coatings materials can be prepared.     

多自由度仿人型假手设计

为了突破目前假手功能的局限,提高使用者的认可程度,设计了集成化的多自由度假手.它的手指设计采用了两种四连杆机构,基关节和中关节之间采用欠驱动连杆传动,能进行自适应抓取;中关节和远关节之间采用耦合连杆传动.手里有三个驱动电机,食指、拇指分别由一个电机驱动,其他三个手指由一个电机驱动.手指上安装了位置和力矩传感器.控制系统由两个DSP控制板组成,不仅实现了基于两路肌电信号的假手动作识别,并且可以进行手指的位置和力矩控制.抓取实验显示这个假手具有很高的抓取能力和灵巧性.     

HIT/DLR仿人假手拇指机构的研究

为了使假手在外观和抓握方式上更加仿人化，基于欠驱动原理系统地设计了仿人假手的拇指．它由一个电机驱动，2个关节组成．其设计和以往假手的拇指有较大的不同：倾斜于手掌放置，其电机、带轮和谐波减速器全部嵌入在手掌内部；可以在抓握时沿空间上一锥面运动；将欠驱动原理在手指的运用上，从平面运动拓广到空间的运动．这使得假手拇指在外型和运动方式上和人的拇指极其相似．并对拇指的空间连杆机构进行了运动学分析，以确定其结构参数．实验表明，所设计的仿人拇指和人的拇指极其接近，并且在抓握时和其他手指配合，具有很强的自适应能力，能够实现对复杂物体的包络、精确抓握和力量抓握．使该假手更加美观、仿人、实用．     

欠驱动假手手指抓取力的研究

为了满足欠驱动手进行复杂作业的需要,基于欠驱动原理建立了手指对物体的抓取力模型和基于力的阻抗控制策略.对应于任一手指姿态,抓取力模型可以准确得到基关节抓握力矩和手指各指节抓取力的关系;采用基于力的阻抗控制策略,实现了基关节抓取力控制.实验证明,手指能够稳定地抓取鸡蛋这样比较滑、容易碎、形状复杂且有一定质量,需要稳定和平衡抓取力的物体,其成功率达80%以上.而这是单纯用手指的基关节力控制很难做到的(成功率只有不到20%).手指抓取力模型和阻抗控制策略的建立大大增强了假手进行复杂作业,抓取复杂物体的能力.     

基于EMG的假手实时力跟踪控制

针对商业假手灵活性及智能化水平较低的问题,进行了具有力矩/位置感知的五指假手及其控制方法的研究.以人体前臂肌电信号（EMG）为控制源,以力传感器检测指尖法向力,通过SVR支持向量机（Support Vector Regression,SVR）构建了指尖力的预测模型;采用网格搜索法确定模型的参数,缩短了训练时间,提高了模型的泛化能力.通过在线预测,结合带有二阶微分跟踪器的模糊PID控制方法实现了指尖施力实时跟踪;速度快,超调小,鲁棒性强,提高了假手的控制水平.     

基于虚拟弹簧的欠驱动手指的动力学建模和控制

采用虚拟弹簧对2关节欠驱动手指进行了动力学建模。并使用该方法建立实际的3关节欠驱动手指的动力学模型,通过动态控制实验验证了动力学模型的正确性。该方法不仅避免了求解微分几何方程,并且直接派生出可解耦的动力学模型。可直接进行逆动力学分析、仿真和实时控制。同时,建立了基于动力学模型的速度观测器,用于轨迹跟踪,弥补了欠驱动手没有速度传感器的缺点,补偿了欠驱动环节造成的不确定因素。与PID或计算力矩法相比较,其轨迹跟踪误差更小,动态控制效果更好。     

虚拟现实灵巧手姿态力度控制算法与仿真

针对灵巧手虚拟现实的控制,提出了数据手套控制手指关节角度,肌电信号进行抓取力度控制的方法.建立了虚拟现实灵巧手模型,根据神经网络算法实现前臂肌电信号对抓取过程中的拇指尖力预测.实验改变拇指接触状态,预测力模型与实际力度对比,验证模型的有效性.该研究可用于智能假肢控制及上肢康复训练、遥操作机器人等领域.     

残疾人用Partial Finger机构研究

为了解决手指基指节截断患者无法安装功能型假肢的问题,研制了残疾人用Partial Finger.先分析了手指基指节截断患者的手部结构特点,基于被动驱动原理设计了Partial Finger的机械本体.基于拟人化的思想研究了手指的关节运动规律,设计以近似等比例传动的杆件参数.进行了运动学分析及样机性能实验.Partial Finger样机外形比成年人小指略小,采用残存基指节驱动,具有侧摆和张合两个自由度,手指关节以近似定传动比传动.实验结果表明:Partial Finger可单手安装和拆卸,指尖最大出力10.7N,外形和运动状态与人手指相似,疲劳实验5万次以上未出现问题,配合其他手指可完成近95%的手部功能.     

欠驱动水面船舶的非线性滑模轨迹跟踪控制

针对模型参数存在不确定性和风、浪、流时变干扰的三自由度欠驱动水面船舶动态轨迹跟踪控制问题,根据滑模控制对系统的不确定性和外界干扰具有鲁棒性的特点,提出了一种新型的非线性滑模控制律设计方法.在设计时根据欠驱动水面船舶的固有特性,船舶在横向上没有驱动,如果要同时控制船舶水平面位置和艏摇角3个自由度的运动,就需要分别引入关于纵向跟踪误差的一阶滑动平面和关于横向跟踪误差的二阶滑动平面来间接设计控制律.仿真结果表明,所设计的控制器能够使船舶跟踪虚拟船产生的参考轨迹,对参数不确定和外界扰动具有强的鲁棒性.     

多抓取模式下人手握力的肌电回归方法

为实现假手抓取物体时的力控制,采用支持向量机回归算法从多通道肌电信号中实时萃取握力信息.利用6通道表面肌肤电极采集人体前臂肌电信号,采用一枚6维力传感器记录人手施力信息,讨论了随意捏取以及3种规范化捏取模式下两者的回归精度,并进行了跨期次精度验证及多方法比较实验.结果表明,采用支持向量机方法能够获得较好的跨期次回归性能:随意捏模式均方误差(6.31±1.20)N,相关系数平方0.85±0.05;规范化模式均方误差(5.04±0.67)N,相关系数平方0.90±0.03.结合模式分类算法,在线握力回归误差可达5 N左右,误差率在10%以内.