FNS Parameter Selection and Upper Limb Characterzation

The design of a controller for functional neuromuscular stimulation requires characterization of the plant, i. e., the neuromuscular system involved. The present paper is concerned with the modeling and identification of the elbow flexion/extension and wrist pronation/supination systems. These movements can be performed successfully by the surface stimulation of the biceps, triceps, and pronator teres. The scatter in the plant parameters between subjects and for a given subject as a function of time, electrode placement, etc., is outlined. The nonlinear muscle gain is approximated by a threshold below which the torque is zero, followed by a linear region. A least squares identification technique using a pseudorandom binary sequence input returned best fit for a third-order model for both the elbow and wrist dynamics. The dependence of the complex poles on the input signal bandwidth and level of coactivation is examined. The differences in parameters between the wrist and elbow systems are calculated. The results are used to establish design requirements for an appropriate controller.     

基于自适应按需辅助的上肢镜像控制策略

为了提高偏瘫患者在镜像康复训练过程中的主动性与系统抗干扰性,该文提出一种基于自适应按需辅助的上肢镜像控制策略。该策略主要包括镜像控制和自适应按需辅助控制两个模块,镜像模块采集健侧位置解算出患侧期望位置,与患侧实际位置比较得到位置偏差;按需辅助模块结合传统阻抗控制和一种患肢运动状态评估方法,自动实时调节对患肢的辅助力大小,以实现患肢主动力矩的最大化。该文设计了两项实验,分别验证本策略对患者主动性和系统抗干扰性的提升效果,实验结果表明,对于镜像康复训练系统使用所提方法有效减小了56.9%的平均辅助力,患肢跟随健肢的位置精度为5.6%,能有效补偿89%的干扰外力。因此所提方法有效提升了训练者的主动性,同时具有良好的抗干扰性,满足镜像康复训练的要求。     

一种上肢康复机器人的力矩控制系统设计

针对目前上肢康复机器人的输出力矩控制不便的问题,设计了一种基于磁粉离合器的力矩控制系统,并给出了相应的驱动电路。磁粉离合器能根据驱动电路的驱动电流输出相应的传递力矩,进而可以控制上肢康复机器人的输出力矩。经应用表明,该系统控制简便、安全性高,符合不同康复训练模式下对输出力矩的要求,为实时控制康复机器人的输出力矩提供了可行性验证。     

基于SVM的上肢康复机械臂轨迹跟踪预测控制

针对上肢康复训练机械臂具有强耦合、非线性和时变的特点,设计了基于SVM（支持向量机）的轨迹跟踪预测控制器。采集机械臂系统的输入和输出数据,通过SVM辨识得到广义逆系统,与原系统串联实现解耦。对解耦后的系统,采用SVM辨识预测模型和PSO优化滚动控制序列的预测函数控制方法,并从其内模结构分析了系统的稳定性和鲁棒性。实验结果表明,该方法能够平稳高精度地实现轨迹跟踪。     

Prediction of Distal Arm Posture in 3-D Space From Shoulder Movements for Control of Upper Limb Prostheses

C5/C6 tetraplegic patients and transhumeral amputees may be able to use voluntary shoulder motion as command signals for a functional electrical stimulation (FES) system or a transhumeral prosthesis. Such prostheses require, at the most basic level, the control of endpoint position in three dimensions, hand orientation, and grasp. Spatiotemporal synergies exist between the proximal and distal arm joints for goal-oriented reaching movements as performed by able-bodied subjects. To fit these synergies, we utilized three-layer artificial neural networks. These networks could be used as a means for obtaining user intent information during reaching movements. We conducted reaching experiments in which subjects reached to and grasped a handle in a three-dimensional gantry. In our previous work, the three rotational angles at the shoulder were used to predict elbow flexion/extension angle during reaches on a two-dimensional plane. In this paper, we extend this model to include the two translational movements at the shoulder as inputs and an additional output of forearm pronation/supination. Counterintuitively, as the complexity of the task and the complexity of the neural network architecture increased, the performance also improved.     

Electrode characterization for functional application to upperextremity FNS

A quantitative method has been developed to characterize the isometric force vectors of electrically stimulated paralyzed muscles of the thumb. The vectorial force output as a function of the stimulus level was measured for individual electrode/muscle combinations in a number of intramuscular and epimysial electrodes implanted in paralyzed thenar muscles of cervical level spinal cord injury subejcts. Vectors are used to determine the output characteristics of each electrode/muscle combination. The characteristics studied include: the strength of the contraction, the stimulus level at which fibers from other muscles are stimulated, the recruitment gain of force, dependency of the output on the skeletal position, and the direction of force produced. These characteristics can then be used to select stimulus parameters to produce coordinated hand motion and force generation by functional neuromuscular stimulation (FNS). The range of muscle force and direction for each electrode/muscle combination showed considerable variation between subjects and between electrodes in the same subject. This variation is primarily due to differences in electrode placement within the muscle. Comparison between intramuscular and epimysial electrodes demonstrated similar characteristics in the force vector output. Preliminary results show the potential for using the force vector output to predict the cocontracted output of two muscles.     

Upper Extremity Limb Function Discrimination Using EMG Signal Analysis

A signal analysis technique is developed for discriminating a set of lower arm and wrist functions using surface EMG signals. Data wete obtained from four electrodes placed around the proximal forearm. The functions analyzed included wrist flexion/extension, wrist abduction/adduction, and forearm pronation/supination. Multivariate autoregression models were derived for each function; discrimination was performed using a multiple-model hypothesis detection technique. This approach extends the work of Graupe and Cline [1] by including spatial correlations and by using a more generalized detection philosophy, based on analysis of the time history of all limb function probabilities. These probabilities are the sufficient statistics for the problem if the EMG data are stationary Gauss-Markov processes. Experimental results on-normal subjects are presented which demonstrate the advantages of using the spatial and time correlation of the signals. This technique should be useful in generating control signals for prosthetic devices.     

Control Schemes for Driving Electro-optic Array Beam Deflectors

The beam deflectors based on electro-optic phased array（EOPA） is mainly described, and then an analysis on existing control schemes for driving the EOPA beam deflectors, based on custom hard-wired electronics or based on software in a microcontroUer, is made. Compared with these, a driving and control system for a multi-channel EOPA beam deflector is presented, in which the control assignment is implemented with a field programmable gate array（FPGA） chip. For different performance requirements, two control schemes, one with the serial scheme and another with the parallel scheme, have been explored and rapidly prototyped in Xilinx FPGA chips. With the control structures for the EOPA beam deflector, scanning rates of 588 kHz and 5 MHz can be respectivelv reached.     

基于QoS的无线ATM网的MAC协议

首先介绍了传统OSI模型中介质接入控制（MediumAccessControl,MAC）协议及其在有线本地网中的应用。接着针对无线ATM网的特．或对两种基于服务质量（Quakity—of－Service，QoS）的MAC协议进行了详细的阐述。最后指出了它们相对于传统的MAC协议的优越性。     

光伏并网系统反孤岛控制策略研究

随着分布式供电系统的逐步发展,反孤岛控制已成为并网供电中不可缺少的环节。文中结合光伏并网逆变器的控制过程介绍了几种传统的反孤岛方法,分析了这些方法中的检测盲区,详细介绍了正反馈频率法的控制原理和控制过程,并给出程序控制流程图,运用Matlab对该方法进行了仿真。仿真结果表明该方法能够快速地检测出孤岛的发生并断开逆变器与电网的连接,无检测盲区,对孤岛效应能够做到有效的防范。     

ATM交换的优先控制方式

本文对采用ATM体制的宽带综合业务数字网业务流的优先控制进行了研究，提出了两种新的优先控制方法。     

玻璃纤维制造中温度控制系统的三种方案

玻璃纤维广泛的应用在居民生活、工业和军事中,制造玻璃纤维需要将玻璃高温熔化,融化的温度需要控制在某一数值.文章主要介绍玻纤制造中温控系统的三种控制方案,针对每一种方案的原理和组成进行介绍,并分析各种方案的优缺点.     

QoS Control Schemes for Two-Stage Ethernet Passive Optical Access Networks

Ethernet passive optical networks (EPONs) have emerged as the one of the most promising candidates for next-generation access networks. These new architectures couple low-cost optics with advanced edge electronics to offer vastly improved scalability over competing digital subscriber line and cable modem offerings. This paper proposes several novel architectural enhancements for EPON, which will help increase the viability of optical access over a broader range of subscriber access scenarios. Specifically, this paper proposes a two-stage EPON architecture that allows more end-users to share an optical line terminal link, and enables longer access reach/distances (beyond the usual 25 km distance). In addition, a new dynamic bandwidth allocation (DBA) algorithm is proposed to effectively allocate bandwidths between end users. This DBA algorithm can support differentiated services in a network with heterogeneous traffic. We conduct detailed simulation experiments to study the performance and validate the effectiveness of the proposed architecture and algorithms.     

中高层大气临边红外辐射的LTE与non-LTE模拟对比

利用战略高空辐亮度代码(Strategic high-altitude radiance code, SHARC) 和通用大气辐射传输代码 (Combined atmospheric radiative transfer, CART) 模拟分析中高层大气临边红外辐射的算法适用范围。 通过模拟结果的对比,初步验证了CART临边模式的有效性。模拟结果表明,在主要的红外波段上,至少45 km以 下的平流层区域内临边红外辐亮度的计算都可以采取局域热力学平衡模式(Local thermodynamics equilibrium, LTE);不同的红外波段在不同的大气条件下,需要采用非局域热力学平衡模式 (Non-local thermodynamics equilibrium, non-LTE)的高度不同,其中15 $\mu$m波段在至少80 km的切点 高度以下都可以使用LTE模式模拟,但是对于CO$_2$ 4.3 $\mu$m带主导的3$\sim$5 $\mu$m波段和O$_3$ 9.6 $\mu$m带 主导的8$\sim$12 $\mu$m波段,在中间层的多数区域内就必须采用non-LTE模式。     

An Analytic Model for Flow Control Schemes in Communication Network Nodes

A Markov model is developed for a message processing node with batch arrivals and various flow control schemes. In particular, a credit allocation pacing control mechanism, previously modeled only by simulation, is represented analytically. The primary application is the network-independent flow control of messages between networks which may have quite different characteristics, via a gateway, but the approach is sufficiently general for modeling many servers or whole subnetworks in any queueing system. A closed form solution to the model's balance equations cannot be found, and direct solution is impracticable due to their number. However, by identifying invariants and making physically realistic approximations, the size of the state space is reduced to such an extent that direct numerical solution does become viable. In particular, the credit allocation scheme is shown to be equivalent to the node's operation in different modes, each with its own buffer capacity, so that credit control need not be modeled explicitly, and no approximation is incurred. Accuracy is assessed by comparison with the results of explicit simulations of a selection of nodes of this type with various parameterizations. Finally, we suggest applications for the model in the assessment and comparison of performance under various congestion control schemes and propose some new stabilizing mechanisms.     

Comments on "Upper Extremity Limb Function Discrimination Using EMG Signal Analysis" and the Relationship Between Parallel-Fltering and Hypothesis-Testing Limb Function Classifiers

A continuity which is not readily apparent exists between certain limb function classification algorithms based on time series models of the surface EMG for use in the control of prostheses and orthoses. Superficially, the parallel-filtering system proposed by Graupe et al. [1], [2] appears to be arbitrary, inconsistent, and ad hoc in nature, and has been criticized as such [3] . Doerschuk et al. independentty developed a multichannel decision algorithm for limb function descrinination within the framework of classical detection theory using multiple-hypothesis testing [3]. This conimtihication establishes the fundamental equivalence of the two algorithms by showing that the system advocated by Graupe is in actuality a degenerate form of that proposed by Doerschuk when conditions of equal residual variance and a priori probabilities are met. A theoretical basis for Graupe's system is presented and its relationship to the multiple hypothesis test of Doerschuk is derived which unifies the contributions of both groups.     

光伏并网系统反孤岛控制策略仿真分析

结合光伏并网逆变器的并网控制过程,介绍了一类基于主动偏移技术的反孤岛检测方法原理和实现过程,并结合IEEE Std.2000-929标准中的技术规范对仿真模型进行了分析,验证并比较了此类方法的有效性和适用性。     

A Comparative Study of Predictive Transmit Power Control Schemes for S-UMTS

Transmit power control is indispensable in Direct Sequence Code Division Multiple Access (DS/CDMA) based systems such as the Satellite Universal Mobile Telecommunication System (S-UMTS). Since S-UMTS aims at achieving close integration with the terrestrial component (T-UMTS) in its complementary role, it is going to implement closed-loop transmit power control (TPC) at a slow rate of once every frame. In addition, predictive schemes can be used to mitigate the effects of delay. In this regard, recursive-least-squares (RLS) and least-mean-square (LMS) algorithms are normally employed. The RLS algorithm has a higher convergence rate than the LMS algorithm: an attractive attribute when the fading process abruptly changes. The LMS algorithm, on the other hand, has better tracking property than the RLS algorithm: an attractive attribute when the changes in the fading process are persistently slow. However, the mobile satellite system channel exhibits both attributes: abrupt changes and slow drifts. In this paper, therefore, we compare the performance of predictive TPC based on the RLS and the LMS algorithms for S-UMTS with the conventional TPC as a reference. We demonstrate that the predictive TPC schemes perform better than the conventional TPC scheme. However, the performance gain achieved depends on the predictive algorithm used, the environment in which the user equipment is operating, and loop delays. We show that, in general, the LMS based predictive TPC offers better performance than the RLS based predictive TPC scheme in S-UMTS environment.Harry S. H. Gombachika is currently a Senior Lecturer in Telecommunications at the University of Malawi. He received a B.Sc. in Electrical Engineering from the University of Malawi in 1990, an M.Sc. in Electrical Engineering from the State University of New York at Buffalo, USA in 1996, and a Ph.D. in Electrical Engineering from the University of Surrey, UK in 2003. He joined the University of Malawi in 1990 as a staff associate and has since worked as an assistant Lecturer and Lecturer. From 1998 to 2000 he worked as the head of the Electrical Engineering department. His research interests include telecommunication networks for rural areas and capacity enhancing techniques for mobile communication systems.Rahim Tafazolli is the Head of Mobile Communications Research Group in CCSR, School of Electronics and Physical Sciences. His research activities are on optimization techniques for mobile multimedia networks, mainly on advance Resource management, Mobility management and Media Access Control. He has published more than 300 research papers in refereed journals, international conferences and as invited speaker. He currently has more than 15 patents in the field of mobile communications. He is advisor and consultant to a number of mobile companies and external examiner to Birmingham University (UK), and Nanyang University (Singapore). He is the founder and the past Chairman of International Conference on 3G Mobile Technologies. He is also member of IEE Committee on the UK Regulations on Information Technology & Telecommunications, a member of the EU Wireless Strategy Initiative (WSI) Think-Tank group, Chairman of New Technologies group of Wireless World Research Forum (WWRF), and academic co-ordinator of the UK Mobile VCE (Virtual Centre of Excellence).Barry Evans was educated at the University of Leeds, obtaining BSc (1st Class Hons.) and Ph.D. degrees in 1965/8 respectively. He then joined the British Telecom sponsored team at the University of Essex (Lecturer-Reader 1968-83) where he was responsible for Telecommunications Systems post-graduate activities and radio and satellite research. In 1983 he was appointed to the Alex Harley Reeves Chair of Information Systems Engineering at the University of Surrey. In 1990 the research was brigaded into a new research centre at Surrey (the model for future developments at Surrey)—the Centre for Satellite Engineering Research. In 1996, he became Director of the new Centre for Communication Systems Research (CCSR) within the School of Electronics & Physical Sciences. From 1998 Barry was Dean of Engineering at Surrey overseeing the restructuring of engineering on the Surrey campus. From August 2001 he was appointed Pro-Vice-Chancellor for Research and Enterprise. Barry Evans was instrumental in setting-up, within Foresight, the idea of Virtual Centres of Excellence. He has served on the MOD DSAC Committee for the ten years, which involves advising MOD on its research programmes. He was also the U.K. delegate on the COST 252, 253 and 272 Committees as well as a delegate to several ETSI Committees. He is editor of the International Journal of Satellite Communications and the author of three books on telecommunications and satellites as well as over 400 papers in learned journals. He was elected to a Fellowship of the Royal Academy of Engineering in 1991.     

Comments on "Upper Extremity Limb Function Discrimination Using EMG Signal Analysis"

The use of stationary models for myoelectric signals (MES's) is sometimes of questionable validity. Also, muscle forces are not always proportional to the concomitant values of the MES variance.     

一种基于体表肌电信号通信原理的功能性电刺激系统设计

基于传感与通信原理和肌电阈值不应期算法,文中设计了一种基于对侧体表肌电信号控制的上肢功能电刺激原型系统。该系统穿戴方便,具有基本的FES功能、对侧控制FES功能以及体表电极刺激和电针刺激两种输出接口。通过对探测端自主肌电脉冲序列利用阈值不应期算法进行解码并实时生成对应的FES刺激脉冲序列,使受刺激肢体跟随探测端肢体力量运动。文中对健康志愿者上肢腕伸动作进行了力量跟踪实验,测试结果显示,探测端腕关节力矩曲线与刺激端腕关节力矩曲线的相关系数为r=0.925 4,均方根误差RMSE=0.184 3。实验结果显示,该系统能够使志愿者刺激侧腕伸肌较好的跟踪探测端肌肉发力情况,完成腕伸运动功能重建。该原型系统对于偏瘫上肢康复训练具有重要的临床意义。