Evolving toward the next-generation Internet: challenges in thepath forward

Most people would agree that the Internet is one of the great technical and business success stories of the 20th century, notwithstanding the financial losses that have been experienced by overly optimistic and speculative investors. Even in the context of the current dramatic slowdown in telecommunications investment, the Internet and its supported applications are continuing to revolutionize almost all aspects of our business and personal lives - mostly for the better. The author reviews a subset of the challenges that lie ahead in evolving the Internet to meet the growing and changing needs of its users     

Adaptive CMOS: from biological inspiration to systems-on-a-chip

Local long-term adaptation is a well-known feature of the synaptic junctions in nerve tissue. Neuroscientists have demonstrated that biology uses local adaptation both to tune the performance of neural circuits and for long-term learning. Many researchers believe it is key to the intelligent behavior and the efficiency of biological organizms. Although engineers use adaptation in feedback circuits and in software neural networks, they do not use local adaptation in integrated circuits to the same extent that biology does in nerve tissue. A primary reason is that locally adaptive circuits have proved difficult to implement in silicon. We describe complementary metal-oxide-semiconductor (CMOS) devices called synapse transistors that facilitate local long-term adaptation in silicon. We show that synapse transistors enable self-tuning analog circuits in digital CMOS, facilitating mixed-signal systems-on-a-chip. We also show that synapse transistors enable silicon circuits that learn autonomously, promising sophisticated learning algorithms in CMOS     

基于视觉反馈的机械手运动控制研究

作为工业机器人中的一种,机械手现已广泛应用于众多场合,譬如搬运、焊接、点胶、采摘等。现通过四自由度机械手作为对象进行研究,以双目视觉系统为基础,实现机械手运动过程控制,并且通过实验验证了智能抓取目标物体的功能。     

Visual control of robotic manipulator based on neural networks

A control scheme for a robotic manipulator system that uses visual information to position and orient the end-effector is described. The control system directly integrates visual data into the servoing process without subdividing the process into determination of the position and orientation of the workplace and inverse kinematic calculation. The feature of the control scheme is the use of neural networks for the determination of the change in joint angles required in order to achieve the desired position and orientation. The proposed system is able to control the robot so that it can approach the desired position and orientation from arbitrary initial ones. Simulations for a robotic manipulator with six degrees of freedom are described. The validity and the effectiveness of the proposed control scheme are verified by computer simulations     

浅谈基于PLC的气动机械手控制系统的设计

气动机械手具有成本低、控制方便和机构简单等特点,为了确保自动化设备能够满足实际工作的需要,需要确保工作程序的合理性,充分发挥自动化生产设备的应用效果,确保PLC气动机械手控制系统的合理性.     

基于PLC的机械手控制项目教学研究

文章对基于PLC的机械手控制项目教学进行研究,机械手控制是现代电气控制技术课程中的一个教学项目,通过此项目的学习,培养学生在机电设备电控系统维修及机电设备电气设计等岗位群的职业能力。在教学过程中,以学生为主体,以工作过程为导向,实施教、学、做一体化的教学模式,使学生掌握状态转移图及步进顺控指令的应用方法。     

A frequency-domain approach to learning control: implementation fora robot manipulator

A frequency-domain approach to the analysis and design of learning control laws for achieving a desired repetitive behavior in a dynamical system is presented. The scheme uses two separate filters in order to obtain rapid improvement in a specified bandwidth, while cutting off possibly destabilizing dynamic effects that would bar learning convergence. In this way the trade-off between global convergence conditions and approximate learning of trajectories is made explicit. The synthesis is presented for single-input, single-output (SISO) linear systems, but the method is of general application. The proposed learning controller has been used for exact tracking of repetitive trajectories in robot manipulators. In particular, actuator inputs that enable accurate reproduction of robot joint-space trajectories are learned in a few iterations without the knowledge of the robot dynamic model. Implementation aspects are discussed, and experimental results are reported     

基于BP神经网络的机械臂轨迹控制研究

针对六自由度机械臂耦合性强、时变、非线性等性能,基于拉格朗日动力学建模方法,文章采用BP神经网络逼近模型,实现高精度轨迹跟踪。该方法根据六自由度机械臂本体采集的数据进行黑箱辨识建模解耦,建模过程采用BP神经网络逼近,提升建模精度、简化建模过程。针对解耦后的系统,还需建立PID闭环控制器进一步实现轨迹跟踪控制。仿真及实验结果表明,基于BP神经网络的PID控制器能够改善系统的鲁棒性和稳定性,并有效抑制抖动。     

A motion control strategy based on equivalent mass matrix inmultidegree-of-freedom manipulator

This paper describes a decoupling motion control strategy based on an equivalent mass matrix in operational space. In the conventional approach, the equivalent mass matrix is defined as a function of Jacobian matrix and inertia of manipulator. Therefore, it is difficult to know the variation of the equivalent mass matrix precisely and to select it arbitrarily. This makes it difficult to realize the decoupling motion controller in the operational space. To improve the above problem, the authors introduce a robust control strategy based on a disturbance observer. In the observer-based approach, the equivalent mass matrix is determined arbitrarily independently of configuration and inertia variation of the manipulator. First, the equivalent mass matrix based on robust control is derived. Second, a simplification method of an operational space controller is discussed by using the equivalent mass matrix. Several experimental results are shown to confirm the validity of the proposed methods     

From theory to practice: toward a typology of project-managementstyles

Research literature on the management of projects has been quite slow in its conceptual development and still suffers from a scanty theoretical basis. One of the main impediments in the study of projects has been the absence of constructs and the little distinction that has been made between the project type and its managerial and organizational style. Based on the findings in a field study of 26 case projects, this research shows that there is a need to adopt a more project-specific contingency approach to project management in organizations. This study explores a two-dimensional theoretical model for the classification of technical (or engineering) projects. Projects are classified according to four levels of technological uncertainty at the time of project initiation and three levels of system scope, which is their location on a hierarchical ladder of systems and subsystems. Considerable differences were found in management style, project organization and operational practice when moving along each of the model's two axes. Differences also were observed in simultaneous change in both dimensions. The findings suggest a handful of practical and managerial implications. They are based on the premise that a proper project classification prior to project initiation and a carefully selected management style may lead to better implementation and to an increased chance of project success     

Second-order kinematic control of robot manipulators with Jacobiandamped least-squares inverse: theory and experiments

This paper describes the application of a closed-loop inverse kinematics algorithm to kinematic control of a robot manipulator. The scheme is formulated at the second-order level, i.e., in terms of velocity and acceleration variables, so as to allow the use of joint space computed torque control. A damped least-squares inverse of the Jacobian is used to ensure feasible joint motion in the neighborhood of kinematic singularities. The theoretical analysis of algorithm convergence is performed on the basis of a Lyapunov argument. The results of experiments on a six-joint industrial robot with open control architecture are presented     

Traffic control: From hand signals to computers'

An overview is given of current applications of computers to traffic control. It includes a discussion of types of hardware and control strategies used in computerized systems developed for the control of urban street networks, as well as critical traffic links such as freeways and tunnels. Some remarks are made concerning possible future development in the use of computers for better management of traffic facilities.     

Automatic control for a miniature manipulator based on 3D vision servo of soft objects

This paper presents a new strategy for automating three-dimensional miniaturized manipulators using a visual feedback. This automation scheme can be used to handle the challenges associated with manipulation of minute soft components such as biological entities. The developed vision control system combines a depth and planar motion control using a single camera and an auto focus algorithm. This visual process was conducted by applying image segmentation and probe recognition along with depth alignment. To demonstrate the feasibility, reliability and robustness of this newly proposed strategy, extensive computer simulations were performed on images of a Zyvex® nanomanipulator obtained using a Scanning Electron Microscope (SEM). Also, a prototype manipulator with a visual feedback and an automatic controller was constructed and tested using soft elements. The results showed good accuracy and robustness of the end-effector recognition, positioning and aligning without occlusion difficulties.     

MCCA: a high-throughput MAC strategy for next-generation WLANs [medium access control protocols for wireless LANs]

Wireless LAN technology has been shown to he a revolutionary development during the last decade. Recently popularized IEEE 802.11a/g-based products can support up to 54 Mb/s physical layer rate and provide wireless access to the Internet. However, in order to deal robustly with the unreliable wireless nature, the 802.11 medium access control protocol has a relatively large overhead and hence, the throughput performance is much worse than the underlying physical layer rate. Moreover, along with many emerging applications and services over WLANs, such as voice over WLAN and audio/video streaming, the demand lor faster and higher- capacity WLANs has been growing recently. In this article, we propose a new medium access control protocol for the next-generation high-speed WLANs. The proposed medium access control, called multi-user polling controlled channel access, is composed of two components: multi-layer frame aggregation, which performs aggregation at both the medium access control and the physical layers; and multi-user polling, used to reduce the contention overhead and in turn, achieve higher network utilization. Multi-user polling controlled channel access is compared with the 802.11e-enhanced distributed channel access medium access control. Highly enhanced medium access control efficiency can be achieved by applying multi-user polling controlled channel access. We show the improved medium access control performance in terms of the aggregate throughput of non-QoS Hows with relevant QoS requirements.     

Congestion control in wireless sensor and 6LoWPAN networks: toward the Internet of Things

The Internet of Things (IoT) is the next big challenge for the research community where the IPv6 over low power wireless personal area network (6LoWPAN) protocol stack is a key part of the IoT. Recently, the IETF ROLL and 6LoWPAN working groups have developed new IP based protocols for 6LoWPAN networks to alleviate the challenges of connecting low memory, limited processing capability, and constrained power supply sensor nodes to the Internet. In 6LoWPAN networks, heavy network traffic causes congestion which significantly degrades network performance and impacts on quality of service aspects such as throughput, latency, energy consumption, reliability, and packet delivery. In this paper, we overview the protocol stack of 6LoWPAN networks and summarize a set of its protocols and standards. Also, we review and compare a number of popular congestion control mechanisms in wireless sensor networks (WSNs) and classify them into traffic control, resource control, and hybrid algorithms based on the congestion control strategy used. We present a comparative review of all existing congestion control approaches in 6LoWPAN networks. This paper highlights and discusses the differences between congestion control mechanisms for WSNs and 6LoWPAN networks as well as explaining the suitability and validity of WSN congestion control schemes for 6LoWPAN networks. Finally, this paper gives some potential directions for designing a novel congestion control protocol, which supports the IoT application requirements, in future work.

     

From trend charts to control charts: setup tests for making theleap

Statistical tests are developed to provide an operational definition of the term `under control' for application in deciding whether trend charts in semiconductor operations should be implemented as control charts, which often require considerable investment in responding to special cause flags. The decision rules derive from Monte Carlo simulations of traditional special cause flags modified for sample size to provide constant and low probabilities of inappropriate process rejection, to help ensure easy tracing of underlying problems and to help ensure large improvements in process capability from investment in fixes. The tests maintain the high efficiency of time series analysis intrinsic to traditional special cause flags. That uncompensated effects of sample size in control chart setup invite wildly uncontrolled risk of rejecting good processes is shown. A table of decision rules is provided to facilitate application of the setup tests at a constant and low risk of rejecting good processes     

基于人面智能门禁系统的采集与控制系统设计

随着社会的发展,快速有效的身份自动验证要求日益迫切,人脸是最自然最直接的特征.基于人面智能控制的家用防盗门禁系统以人脸作为身份识别,判断来者的合法性,并以此来控制门的开关.文中实现了以89C51为核心处理器的门禁系统的采集与控制系统的设计.当检测到有人来时触发系统工作：由光敏采集外界光线强度控制照明系统;进行图像采集,如果人脸图像难以采集语音提示进行姿态调整;将采集到的图像与图像库中的合法用户图像进行比较,一致则是合法进入者打开电动门,若不一致进行语音报警提示其离开.经过实验,系统实现了智能门禁控制,工作稳定.