A new traffic-signal control for modern roundabouts: method and application

When the circulatory roadway of a roundabout has more than two lanes, the vehicles' weaving and merging cause large traffic and safety problems. In this paper, a new method of traffic-signal control for modern roundabouts is proposed to solve problems by eliminating the conflict points and weaving sections at a roundabout with different traffic-flow rates on each approach, which normally appear in the real world. A second stop line is set exclusively for the left-turn traffic on the circulatory roadway. It is beside the first stop line on the approach. Traffic signals are installed before each stop line to eliminate the conflicts between the traffic flows on the approaches and the left-turn traffic flows on the circulatory roadway. Left-turn vehicles on the circulatory roadway will stop before red signals to avoid weaving. Equations are derived to compute the signal cycle length and the green time for each traffic flow, considering the limited queue on the circulatory roadway. Capacity and delay are also formulated to evaluate the roundabout's performance. This traffic-signal control has a successful application of a roundabout in Xiamen, China, to solve the very serious traffic-congestion problem. The signal-timing scheme was computed with the proposed equations, as well as the capacity and delay. Pictures taken before and after the improvement show the operation. After the improvement, the roundabout capacity increases 72.1% and the average delay of each vehicle decreases by 20 s.     

An adaptive tracking problem for a family of retarded time-delay plants

Most of the existing switching control techniques are developed specifically for finite-dimensional linear time-invariant (LTI) systems. In many practical applications, however, it is essential to take time delay into consideration in the modelling as the control system can be highly sensitive to delay. In this paper, a multi-model switching control algorithm is proposed for retarded time-delay systems. It is assumed that the plant is represented by a family of known multi-input multi-output, observable, LTI models with multiple delays in the states, and that corresponding to each model in the known family, there exists a high-performance finite-dimensional LTI controller. In addition, it is supposed that a bound on the magnitude of the external inputs and disturbances is available. It is then shown that the proposed switching controller can stabilize the uncertain system, and that under some mild conditions, output tracking can be achieved in the given problem setting. Copyright © 2007 John Wiley & Sons, Ltd.     

蓄意流量攻击下基于确定网络演算的互联电网自适应负荷频率控制策略

蓄意流量攻击通过抢占有限的网络带宽降低正常数据流的时效性。对于网络化负荷频率控制(load frequency control, LFC),流量攻击将造成稳定裕度下降、频率偏差幅度上升甚至越限事故。现有控制方案一般采用单一且固定的控制器保证最大攻击强度下的渐进稳定性,存在设计约束多、保守性大的缺点。因此提出了一种跟随攻击强度自适应调整控制器增益的LFC策略。首先,基于确定性网络演算,得到了无攻击场景下数据流传输延时上边界,并预设了一系列表征不同攻击强度的传输延时范围。其次,通过构造Lyapunov泛函,推导了针对每个攻击强度的控制器设计准则。最后,基于切换控制理论,确定了所提自适应方案所能容忍的最大攻击强度变化频率。仿真表明,与现有控制方案相比,所提方法的频率偏差幅度可下降12.60%,区域控制误差的绝对值误差积分可下降10.85%。     

Smooth switching control for transfer from the Automatic Traveling Mode to the Power Assist Mode of the Skill‐Assist

The objective of this study is to verify a smooth switching control method for transfer from the automatic traveling mode (ATM) to the power assist mode (PAM) of Skill‐Assist. A control law including time‐varying impedance parameters is utilized to attain the objective. The experimental result shows that the transfer from ATM to PAM was successfully performed by the smooth switching control method. © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

基于排队长度的多路口交通信号控制方法

城市区域交通信号控制是一个复杂的问题,排队长度是一个特别重要的参数,提出了一种基于排队长度的多路口交通信号控制方法。该控制方法根据各路口的交通状态信息,利用模糊控制算法协调区域内各路口的交通信号配时,达到整体最优的目的,仿真研究结果表明,相对于传统的定时控制方法,该方法可以取得整体较优的效果。     

Automatic Train Operation Using Autonomic Prediction of Train Runs

In this paper, we present an automatic train control method adaptable to disturbed train traffic conditions. The proposed method presumes transmission of detected time of a home track clearance to trains approaching the station by employing equipment of Digital ATC (Automatic Train Control). Using the information, each train controls its acceleration by a method that consists of two approaches. First, by setting a designated restricted speed, the train controls its running time to arrive at the next station in accordance with predicted delay. Second, the train predicts the time at which it will reach the current braking profile generated by Digital ATC, along with the time when the braking profile transits ahead. By comparing them, the train correctly chooses the coasting drive mode in advance to avoid deceleration due to the current braking profile. We evaluated the effectiveness of the proposed method regarding driving conditions, energy consumption, and reduction of delays by simulation. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 175(3): 65–73, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.10020/eej.21080     

Output shaping in continuous‐time predictive control

In many control applications, it is expected that the system output tracks a desired reference signal. This paper describes a new approach in which the tracking problem is formulated as an output shaping problem. The approach uses the framework of predictive control and imposes the desired reference signal as a constraint on the output. Some simulation results and a real‐time application are also given to illustrate the effectiveness of the proposed method. Copyright © 2007 John Wiley & Sons, Ltd.     

单交叉口交通灯模糊控制器的设计与实现

针对城市单交叉口交通信号控制问题,提出了一种应用模糊控制理论的单交叉口交通灯控制器,并给出了基于大规模可编程逻辑器件的完整设计实现方案.通过感应线圈检测器对4个方向的排队车辆进行统计,并以此为输入查找按照模糊控制规则预先离线运算的控制表,得到绿灯延时.结果表明,与传统的定时控制方式相比,在交叉口交通负荷较小时的情况下,该控制器可以有效的降低车辆等待延时.     

A QoS control scheme using dynamic window size control for wide area ubiquitous wireless network

This paper describes a quality‐of‐service (QoS) control scheme for a wide‐area ubiquitous wireless network which is designed to accommodate many wireless terminals (WTs), such as sensors and actuators, in a large cell area. The purpose of this paper is to establish a QoS control scheme in a medium access control (MAC) layer that can hold the transmission delay of high‐priority class traffic within a predefined value regardless of how much low‐priority class traffic there is. Several QoS control schemes for wireless communication use have been proposed. However, in the wide‐area ubiquitous wireless network, an access point (AP) accommodates many WTs and the AP traffic volume often drastically changes. Therefore, conventional schemes sometimes cannot control the QoS of high‐priority traffic. To solve this problem, we propose a QoS control scheme that calculates a suitable initial back‐off window size of random access for each QoS class by using equations derived from a Markov chain behavior model. The proposed scheme adjusts the window size so as to prevent increased transmission delay of high‐priority traffic. The scheme's performance is clarified by computer simulation. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

A reliability framework for traffic signal control

An important consideration for traffic signal control is that traffic arrivals are not deterministic. The effect of stochastic arrivals is mainly handled by introducing stochastic terms in delay formulas. Although convenient, this approach is somewhat indirect. Moreover, when the degree of saturation is high, the system becomes transient; it is questionable whether a static or time-invariant result in the form of a delay formula is applicable. In this paper, instead of relying on steady state or equilibrium probability measures, the transient effect is captured by analyzing the state of the system from cycle to cycle based on a probabilistic treatment of overflow in an event tree. This approach can be used to analyze an existing timing plan or to design a timing plan that satisfies a certain clearance reliability requirement. Some numerical results are included to demonstrate this approach.     

An adaptive switching scheme for uncertain discrete time‐delay systems

In this paper, an adaptive switching control algorithm is proposed for the stabilization of uncertain discrete‐time systems with time‐varying delay. It is assumed that the time delay is unknown and time varying, nonetheless bounded with a known bound. It is supposed that the system is highly uncertain, and that a set of controllers are designed (off‐line) to stabilize the system in the whole uncertain parameter space; subsequently, a switching scheme is developed to stabilize the uncertain time‐delay system. A thorough stability analysis for the uncertain time‐delay system under the mentioned control scheme is provided. Furthermore, an upper bound on the allowable rate of change of the system parameters and delay is obtained. Simulation results are presented to show the efficacy of the proposed switching scheme. Copyright © 2008 John Wiley & Sons, Ltd.     

Adaptive backstepping control for a class of time delay systems with nonlinear perturbations

The sliding mode control method has been extensively employed to stabilize time delay systems with nonlinear perturbations. Although the resulting closed‐loop systems have good transient and steady‐state performances, the designed controllers are dependent on the time delays. But one knows that it is difficult to obtain the precise delay time in practical systems, especially when it is time varying. In this paper, we revisit the problem and use the backstepping method to construct the state feedback controller. First, a coordinate transformation is used to obtain a cascade time delay system. Then, a linear virtual control law is designed for the first subsystem. The memoryless controller is further constructed based on adaptive method for the second subsystem with the uncertainties bounded by linear function. By choosing new Lyapunov–Krasovskii functional, we show that the system state converges to zero asymptotically. Via the proposed approach, we also discuss the case that the uncertainties are bounded by nonlinear functions. Finally, simulations are done to verify the effectiveness of the main results obtained. Copyright © 2007 John Wiley & Sons, Ltd.     

Coordinated road-junction traffic control by dynamic programming

This paper presents a novel approach to road-traffic control for interconnected junctions. With a local fuzzy-logic controller (FLC) installed at each junction, a dynamic-programming (DP) technique is proposed to derive the green time for each phase in a traffic-light cycle. Coordination parameters from the adjacent junctions are also taken into consideration so that organized control is extended beyond a single junction. Instead of pursuing the absolute optimization of traffic delay, this study examines a practical approach to enable the simple implementation of coordination among junctions, while attempting to reduce delays, if possible. The simulation results show that the delay per vehicle can be substantially reduced, particularly when the traffic demand reaches the junction capacity. The implementation of this controller does not require complicated or demanding hardware, and such simplicity makes it a useful tool for offline studies or real-time control purposes.     

Swing‐up and stabilization control of a cart– pendulum system via energy control and controlled Lagrangian methods

This paper addresses a swing‐up and stabilizing problem for a cart– pendulum system, which consists of a pendulum and a motor‐driven cart. Existing methods are based on the strategy of swing‐up of the pendulum by energy control methods, then switching the controllers to balance the pendulum when it approaches the upright position. The switching angle influences significantly control performance, so the pendulum might fall down if the angle is inadequately chosen. This paper proposes a swing‐up and stabilizing control method which makes it possible to determine an appropriate switching angle more arbitrarily. In addition to the energy control method for swing‐up, a stabilizing method based on controlled Lagrangians is adopted instead of a linear controller. The attractive domain of the closed‐loop system with this method can be known in advance and is wider than with linear controllers. In this way, our proposed control strategy overcomes the difficulty in choosing the switching angle of the controllers. An experimental result illustrates the effectiveness of the proposed method. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 160(4): 24– 31, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20534     

基于光储控制的微电网改进预同步控制及离并网切换策略研究

光储配合的微电网预同步控制和离并网切换策略是保证电网平滑运行的重要支撑。针对微电网和大电网之间存在的电压幅值、相位和频率偏差等问题,基于储能逆变器的V/f控制,引入大电网电压作为控制器参考量,简化预同步控制环节结构,提出一种改进的预同步方法。基于离网到并网负序电流变化,提出孤岛检测方法,确定离网信号的发出。考虑光储电源输出随机性和离并网切换特点,提出两储能单元分时转换V/f控制模式和P/Q控制模式的离-并网切换策略,分时控制降低系统切换冲击。设计离-并网切换试验、并-离网切换试验、三组光储出力并网策略对比实验,仿真运行结果表明,改进预同步方法在保证离-并网电压幅值、频率、相角偏差分别小于1%、±0.1 Hz、5°的同时,结构简单;基于两储能单元切换策略的并-离网切换时间缩短、冲击降低,验证了改进预同步方法和基于两储能单元切换策略的有效性。     

Adaptive transfer function-based control of nonlinear process. Case study: Control of temperature in industrial methane tank

The state model-based transfer function models are applied for adaptation of linear controller and disturbance compensator in a feedback/feed-forward control system of nonlinear process. An advantage of the presented adaptation method is the avoidance of artificial disturbances or iterative identification procedures for on-line estimation of process dynamic parameters. The adaptation is based on linearization of the process model at each sampling time about the current state point, independent of the process being at steady-state or transient conditions. The linear time-varying dynamics model is updated on-line using measured values of process variables and reduced to the first-order plus time delay transfer function models in order to directly apply well-developed controller tuning rules. Computational aspects of the adaptation method are discussed and computation algorithms are presented. The adaptive feedback/feed-forward control system was applied for controlling temperature in industrial methane tank, dynamic parameters of which vary in a wide range due to variations of methane-tank process load and external conditions. The heat balance-based process state model is developed and validated using observation data of real plant. Computer simulation of the proposed control system performance under extreme operating conditions demonstrates fast adaptation of controller parameters, robust behaviour and significant improvement in the controllers' performance compared to that of fixed-gain controllers. Copyright © 2007 John Wiley & Sons, Ltd.     

基于红绿灯控制系统的LED城市路灯方案设计

针对目前城市路灯照明系统存在的问题,如自动化管理水平还不很高、系统可靠性不高、能耗高等,提出了一个较为完善的路灯综合节能控制系统。即将LED路灯装置与交通红绿灯控制系统结合在一起,利用每一路段红绿灯的转换实现对下一路段灯光强弱的控制。将当前市场上LED集灯板上的LED灯分为两组,在满足不同时段照明要求前提下,最大可能地降低功率,节省能耗;同时又能有效地减少LED灯的产热,增加其冷却散热时间,从而提高LED路灯的散热效率,大大延长LED灯使用寿命。     

基于再励学习和遗传算法的交通信号自组织控制

提出一种将再励学习与遗传算法相结合的遗传再励学习方法对交通信号进行自组织控制,再励学习是针对第五个道路交叉口交通流的优化,修线个信号灯周期的绿性比,而遗传算法产生局部学习过程的全局优化标准,即是修正信号灯周期的大小,这种方法克服了现有的控制方法需要大量数据传输通讯、准确的交通模型等缺陷,将局部优化和全局优化统一起来。通过计算机仿真实验表明了方法有效笥。     

Traffic scheduling in distributed networked control systems with packet losses and delays for power systems voltage stabilization

In this paper, medium access control (MAC) sublayer data traffic scheduling in distributed networked control systems (DNCSs) with networked induced packet losses and delays is investigated for stabilization and control of system dynamics. An effective‐information‐directed distributed sensor selection algorithm is proposed to select sensors to participate in delay‐tolerant information filtering for state estimation. The distributed scheduling algorithm is based on the total amount of effective information for all measurements stored in the sensors. We consider packet loss in wireless networks as a special type of delay, so the impact of packet losses on effective information amount can also be studied for the formulation of distributed scheduling strategy in the presence of packet losses. The distributed data traffic scheduling considering packet losses and delays is carried out in a networked system with data packet dropout governed by a Markov process for voltage regulation and stabilization with distributed energy resources (DERs). Experimental results demonstrate that the scheduling algorithm with awareness of the system dynamic state can well control the power system dynamics. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.