Effects of Physical Parameters and Time-Delay Coefficients on the Amplitude and Frequency Bandwidth of Saturation Controller for a Beam Vibration

In this paper, the influence of physical parameters on the width of saturated control frequency band and the influence of time delay parameters on the stability of saturated control system are studied. The analytical solution of the motion equation of the system when the main resonance and the 1:2 internal resonance occur simultaneously is obtained by multiple scale method, experimentally measured natural frequencies of nonlinear beams. The effects of excitation amplitude, delay feedback coefficients and nonlinear coefficients on saturation control are investigated. The results of the study show that the bandwidth of the saturation control can be increased by increasing the value of the external excitation, the nonlinear coefficients enhance the nonlinear phenomena of the system.

Optimal design of Stewart platforms based on expanding the control bandwidth while considering the hydraulic system design

We proposed an optimal design method to expand the bandwidth for the control of large hydraulic Stewart platform.The method is based on generalized natural frequency and takes hydraulic oil into consideration.A Lagrangian formulation which considers the whole leg inertia is presented to obtain the accurate equivalent mass matrix.Using the model,the effect of leg inertia and the influence of design parameters on the generalized natural frequency are investigated.Finally,numerical examples are presented to validate and confirm the efficiency of the mathematical model.The results show that the leg inertia,especially the piston part plays an important role in the dynamics.The optimum diameter ratio of the base to the moving platform is between 2 and 3,and the optimum joint angle ratio of the base to the moving platform is about 1.The smaller joint angles and a longer leg stroke are favorable for raising system frequencies.The system oil should be preprocessed for large platforms with a requirement for good dynamic performance.

A DYNAMIC BANDWIDTH CONTROL SCHEME OF VP IN ATM NETWORKS

This paper proposes an efficient adaptive bandwidth allocation scheme of virtual paths. The bandwidth of a virtual path is dynamically adjusted according to the link residual capacity. The scheme can remarkably reduce the load on node processing and simplify the network architecture, while keeping higher transmission efficiency. The excellent performance is proved by detailed theoretical analyses.

Thermally Controllable Break Junctions with High Bandwidths and High Integrabilities

Break junctions are important in generating nanosensors and single molecular devices. The mechanically con- trollable break junction is the most widely used method for a break junction due to its simplicity and stability. However, the bandwidths of traditional devices are limited to about a few hertz. Moreover, when using traditional methods it is hard to allow independent control of more than one junction. Here we propose on-chip thermally controllable break junctions to overcome these challenges. This is verified by using finite element analysis. Adopting microelectromechanical systems produces features of high bandwidth and independent controllability to this new break junction system. The proposed method will have a wide range of applications on on-chip high speed independent controllable and highly integrated single molecule devices.

基于PI参数的二阶线性自抗扰控制参数整定

线性自抗扰控制是一种不依赖于被控过程模型的控制方法,具有很好的工程应用潜力。目前,工业控制过程中大多采用PI控制器,为了确保由调试好的PI控制器平稳切换到线性自抗扰控制器,并使系统仍保持稳定状态,需要合理设置线性自抗扰控制器的参数。为此,在分析二阶线性自抗扰控制器的二自由度等效结构的基础上,推导出其反馈控制器与PID控制器的对应关系,给出一种基于现有PI控制参数直接获取二阶线性自抗扰控制初始参数的方法。最后,在MATLAB/Simulink平台上采用若干典型传递函数和双容水箱液位控制系统进行仿真研究,仿真结果验证了所提方法的有效性。

带宽化调节下的抗扰PID退饱和控制方法

比例–积分–微分(PID)控制的抗饱和设计是一类经典非线性控制问题,理论研究丰富,但工程中广泛使用的仍是积分退饱和这类简易策略.究其原因,现有理论方法过于依赖系统模型和状态空间理论,稳定性条件与调参机制之间关系复杂.本文基于经典退饱和控制结构,首次阐述了“退饱和带宽”概念及退饱和参数调节机理,在此基础上讨论了两类低阶退饱和补偿器的带宽化设计方法.在抗扰PID反馈控制下,结合小增益定理得到退饱和控制的稳定性条件,给出控制参数与退饱和带宽之间的调节关系,实现退饱和控制的带宽化整定.最后,通过数值仿真验证了所提方法的有效性.

基于FOCA的永磁游标电机PI参数自整定

针对磁场定向控制中电流内环和转速外环比例积分(PI)控制器参数整定困难且耗时长的问题,基于Matlab/Simulink的磁场定向控制自整定(FOCA)模块搭建了永磁游标电机磁场定向控制双闭环调速系统参数自整定模型。该模块在PI控制器输出端注入正弦扰动信号,根据系统输入输出数据计算频率响应,基于频率响应自动整定PI参数,同时实现指定的目标带宽和相位裕度。最后通过仿真对比分析各个环路整定前后的控制性能,仿真结果表明使用FOCA模块能够快速自动整定PI控制器参数并且拥有良好的控制性能。

面向2G~5G通信的双频双极化基站天线设计

为满足多种通信制式融合的无线通信需求,提出一款覆盖2G、3G、LTE、Sub-6 GHz波段的交叉偶极子基站天线。2对呈±45°正交的偶极子用以实现天线的双极化特性,辐射单元中的扇形内环、钻石状的外环分别对应天线要实现的低频以及高频波段,可以通过对内环以及外环结构参数的调整实现对2个频段的独立控制。天线上方的寄生贴片用以优化天线阻抗匹配。通过制作实物,测得天线在2个频段分别具有49.9%(1.70~2.80 GHz)和19.2%(3.20~3.88 GHz)的相对带宽,隔离度整体优于20 dB,主视轴的交叉极化比优于21 dB,2个波段的半功率波束宽分别为66°±5°、78°±6°。与已有研究比较,该天线结构简单,在交叉极化和增益方面具有显著优势。

基于迭代策略的自适应ADRC磁轴承控制仿真

针对磁悬浮轴承位置控制过程中存在非线性耦合、内外部扰动不确定性的问题,提出了一种基于自抗扰控制的四自由度磁轴承迭代学习控制策略。首先依据四自由度磁悬浮轴承系统模型搭建自抗扰控制器,其次将估计的总扰动通过间接迭代控制在线调整扩张状态观测器的带宽,实现不同增益下观测器参数的自适应整定。Simulink仿真实验数据表明:系统约在0.14 s处达到稳定,加入干扰后约0.05 s恢复稳定;基于迭代控制的自适应ADRC四自由度磁悬浮轴承控制性能好,同时调节速度快,具有较强的抗干扰能力。经比例-微分型间接迭代学习控制律在线更新带宽后,超调量小且跟踪目标误差积分性能指标小。

基于改进机器学习的无人机中继通信数据调度控制研究

为解决无人机通信网络中数据调度行为中断概率过大的问题,实现对通信资源的合理分配,提出基于改进机器学习的无人机中继通信数据调度控制方法;设计基本网络架构,联合BMRC协议,设置URLLC数据链路单元,联合相关通信数据样本,求解通信中断概率的具体数值,实现对无人机中继通信网络资源的联合优化处理;分别计算时隙分配参量与带宽分配参量,并以此为基础,确定无人机中继位置,实现对中继通信资源的调度;按照机器学习算法标准,定义PCA改进特征,从而完善改进机器学习算法,再联合最优控制器闭环,实现对通信数据调度行为的控制;实验结果表明,改进机器学习算法作用下,随着中继数据累积量的增大,无人机通信网络中数据调度行为中断概率的最大值只能达到7.3%,有效降低了中断概率,符合合理分配通信资源的实际应用需求。

ALOHA机制下VLC系统接入控制算法

为提高可见光通信(VLC)系统的资源利用率,实现系统的高效服务,设计一种ALOHA机制下VLC系统接入控制算法。首先,针对VLC系统建模具有多包接收(MPR)能力的ALOHA服务机制,采用泊松过程刻画数据包到达过程。然后,结合有效容量和有效带宽理论,计算服务质量(QoS)约束下系统可支持的到达强度。构建以到达强度最大化为目标的优化问题并采用灰狼算法(GWO)求解。将灰狼算法与粒子群算法(PSO)进行仿真对比,可以得出灰狼算法的寻优效果好,全局搜索能力强。最后,利用Matlab仿真分析终端数量、未被遮挡概率、多包接收能力对接入到达强度的影响。仿真结果表明,算法可以为VLC系统的接入控制提供一定的指导,提高系统资源利用率。

基于混合馈入型自适应补偿的电网谐波功率放大器超宽频控制

基于电力电子变换器的功率放大器因其灵活易控成为电网电压模拟的理想物理接口之一。针对现有功率放大器控制方法会放大频率偏差、使滤波电路参数漂移以及难以模拟高频谐波的弊病,首先,提出一种混合馈入型自适应补偿的谐波功率放大器超宽频控制策略,以高精度复现宽频电压信号并兼顾动态与稳态性能;然后,设计多变量混合馈入型环路以补偿系统暂态特性;在时域下利用Lyapunov函数推导计及参数漂移的自适应方法以补偿滤波参数不确定性;深入分析并克服混合自适应补偿的数字实现局限性;讨论所提方法作为重复内嵌控制的性能提升;最后,制作样机,进行所提策略动态性能与稳态精度的仿真及实验验证。结果表明:所提方法相较于既有控制具备更快的动态响应、更高的稳态精度以及更宽的跟踪谐波频率范围,可以实现对超宽频参考电压的快速无差跟踪。

车载通信总线带宽资源的控制方法

CAN总线在汽车通信网络中应用广泛且占据着重要地位,但随着电气类功能,尤其智驾和智舱域功能的不断丰富,总线上需要交互的信息量越来越大,总线带宽资源也因此越来越紧张,负载率越来越高。过高的总线负载率将影响信号传输的实时性和稳定性,因此,在网络架构设计之初进行网络带宽资源的管控至关重要,这将影响网络架构的平台化设计和后续功能的拓展。本文从信号层面、总线层面和拓扑层面介绍通信总线的负载率管控方案。

基于带宽优化的ControlNet拥塞避免策略

为了提高ControlNet的快速性和稳定性,提出了基于带宽优化的网络拥塞避免策略。由于ControlNet是由一些相互关联的节点组成的,可以采用生产者/消费者多节点网络的带宽优化方法来控制单个节点的信息传输,提高了网络利用率。根据生产者/消费者多节点网络的通信机制,总结出一套高效的带宽优化算法,并给出详细的算法步骤。以CPU利用率、平均带宽利用率和峰值带宽利用率作为衡量ControlNet网络性能的重要指标,对所设计的带宽优化算法进行验证,实验结果表明,所提出的带宽优化算法能有效解决ControlNet的网络拥塞问题。

高响应交流永磁伺服系统快速电流环带宽扩展方法

交流永磁伺服控制系统中现有电流采样和脉冲宽度调制(Pulse width modulation,PWM)占空比更新的方法延迟时间较长,在一定程度上会影响电机的电流环带宽和动态特性;针对该问题,建立了电流环闭环系统数学模型,分析了电流环的内部延迟和影响电流环带宽的因素,在此基础上提出了一种通过改进电流采样与PWM更新时间的电流环带宽扩展方法。该方法通过提前PWM占空比更新时机来降低电流采样和PWM占空比更新之间的延迟,减小信号传输滞后,从而扩展电流环系统的闭环带宽,提高系统响应速度。仿真与实验结果表明,相比现有电流采样方法,采用新方法的交流永磁伺服控制系统的电流环具有更宽的带宽和更高的动态响应能力,从而提高了交流伺服系统的动态响应能力和稳态精度。该方法可为交流伺服系统在机器人、高端智能装备等对响应速度和定位精度要求较高领域的应用提供参考。

智能制造车间数据通信传输带宽分配方法

当前车间数据通信传输带宽分配模型多为单一分配结构,分配效率较低,导致时延增加。为此,文章提出智能制造车间数据通信传输带宽分配方法。根据当前带宽分配需求,先进行数据传输需求分析,计算出链路带宽配置。以此为基础,采用多阶段的方式,设计传输带宽多目标分配模型,提升分配效率。采用最优平衡修正的方式进一步修正分配结果,实现最终分配。测试选定3条制造车间生产线所形成的数据,与初始的带宽时延标准比对可知:此次所得出的时延被控制在0.5s以下。说明此次所设计的数据通信传输带宽分配方法更为高效、精准,针对性较强,具有实际的应用价值。

基于Σ-ΔADC的伺服系统电流环带宽延拓技术研究

研究了基于Σ-ΔADC的伺服系统电流环带宽延拓技术,旨在提高电流采样精度和电流环带宽。设计了一种与PWM中心对齐的平均电流同步采样方法,以减少采样过程中的噪声和延迟。通过优化PWM更新时序并采用SINC3滤波器的同步策略,实现了电流采样时刻与PWM周期的精准对齐,从而降低了电流环中的谐波干扰。提出了PI分离控制策略,分别为比例控制器和积分控制器配置不同滤波器,以兼顾系统的动态响应和稳态精度。实验结果表明,所提方法使相电流中的谐波幅值降低了80%,转矩反馈波动降低了64%,电流过零点的延迟时间从1.5 ms缩短至0.5 ms,电流跟踪的正弦度显著提升,有效提高了伺服系统电流环的动态性能和稳态精度。

Dynamic resource management using bandwidth brokers

The admission control issue in the design of a centralized bandwidth broker model for dynamic control and management of QoS provisioning is studied. A two-phase differentiated flow treatment based dynamic admission control scheme under the centralized bandwidth broker model is proposed. In the proposed scheme, the flow requests are classified into two classes and get differentiated treatment according to their QoS demands. We demonstrate that this admission control scheme can not only improve the resource utilization but also guarantee the flows＇ QoS. Furthermore, the admission control is divided into two phases： edge admission control and interior admission control. During the interior phase, the PoQ scheme is adopted, which enhances the call processing capability of the bandwidth broker. The simulation results show that the proposed scheme can result in lower flow blocking probability and higher resource utilization. And it also reduces the number of QoS state accesses/updates, thereby increasing the overall call processing capability of the bandwidth broker.

ACOUSTICAL TRANSMISSION LINE MODEL FOR ULTRASONIC TRANSDUCERS FOR WIDE-BANDWIDTH APPLICATION

An improved model for ultrasonic transducers is proposed. By considering only the first symmetric mode, each layer is represented as an acoustical transmission line in modeling of bulk wave transducers. In imaging applications, wide bandwidth and short time duration are required. The approach we have used consists of impedance matching the front face of the piezoelectric transducer to the propagating medium with a quarter wavelength impedance matching layer and inserting an nnmatching quarter wavelength acoustical layer between the rear face and backing material. A heavy backing would degrade the wide-band phenomena, but show a time duration shorter than 0.5 μs for imaging applications. PSPICE code of the controlled source model is implemented to precisely predict the performance of the matched transducers such as impedance, insertion loss, bandwidth and duration of the impulse response. Good agreement between the simulation and experimental results has been achieved.

Streaming and congestion control using scalable video coding based on H.264/AVC

This paper presents a streaming system using scalable video coding based on H.264/AVC. The system provides a congestion control algorithm supported by channel bandwidth estimation of the client. It uses retransmission only for packets of the base layer to disburden the congested network. The bandwidth estimation allows for adjusting the transmission rate quickly to the current available bandwidth of the network. Compared to binomial congestion control, the proposed system allows for shorter start-up times and data rate adaptation. The paper describes the components of this streaming system and the results of experiments showing that the proposed approach works effectively for streaming video.