Energy-Efficient Optimal Guaranteed Cost Intermittent-Switch Control of a Direct Expansion Air Conditioning System

To improve the energy efficiency of a direct expansion air conditioning(DX A/C) system while guaranteeing occupancy comfort, a hierarchical controller for a DX A/C system with uncertain parameters is proposed. The control strategy consists of an open loop optimization controller and a closed-loop guaranteed cost periodically intermittent-switch controller(GCPISC). The error dynamics system of the closed-loop control is modelled based on the GCPISC principle. The difference,compared to the previous DX A/C system control methods, is that the controller designed in this paper performs control at discrete times. For the ease of designing the controller, a series of matrix inequalities are derived to be the sufficient conditions of the lower-layer closed-loop GCPISC controller. In this way, the DX A/C system output is derived to follow the optimal references obtained through the upper-layer open loop controller in exponential time, and the energy efficiency of the system is improved. Moreover, a static optimization problem is addressed for obtaining an optimal GCPISC law to ensure a minimum upper bound on the DX A/C system performance considering energy efficiency and output tracking error. The advantages of the designed hierarchical controller for a DX A/C system with uncertain parameters are demonstrated through some simulation results.

兆瓦级高效紧凑型核动力系统运行特性研究

为研究兆瓦级高效紧凑型核动力系统的运行特性,使用自主开发的热管堆瞬态分析程序TAPIRS(Transient Analysis code for heat Pipe and AMTEC power conversion space Reactor power System)和超临界二氧化碳布雷顿循环的瞬态分析程序SCTRAN/CO_(2)(Super Critical reactors Transient Analysis code/Carbon Dioxide)的耦合程序对其反应性、负荷、冷却水温度和流量等扰动进行了开环动态响应分析,并据此进行了控制系统设计。在此基础上,对线性变负荷、阶梯式变负荷以及甩负荷这三种变负荷运行工况进行了计算分析。结果表明:该核动力系统的转速对扰动的变化较为敏感,需要加以控制;低负荷下旁通会使压缩机流量上升,需对压缩机流量加以控制;系统在控制方案下能以6%FP(Full Power)·min^(−1)的速度实现0%~100%的负荷变动,且可以在任意负荷水平下运行;甩负荷下系统的波动时间变长,但是仍可达到新的稳态进行工作,且各参数处于安全范围内。本研究可为新型核动力系统的概念设计提供参考。

船用柴油机SCR系统控制策略试验研究

为降低船用柴油机NO_(x)排放,分析柴油机选择性催化还原(selective catalytic reduction,SCR)后处理系统的开环、闭环控制策略,对不同策略及工况下NO_(x)转化率及NH3泄露进行试验对比。结果表明:采用开环策略,柴油机功率与额定功率的比为75%以上时,NO_(x)转化效率可达到83%,但不同工况下NO_(x)转化率波动超过20%;采用闭环控制策略,不同工况下NO_(x)转化率稳定在85%左右,尾气中NH_(3)的体积分数低于20×10^(-6);闭环控制策略下NO_(x)转化率具有自调整、高稳定性、响应速度快等优势,可降低NO_(x)排放且尾气中NH3的体积分数在规定范围内。

Controlling Chaotic Cscillations with Input-Output Linearization

In this paper, the nonlinear control of chaotic oscillations was investigated by using the input output linearization control method. The chaotic attitude of a kind of spacecraft was discussed. It is demonstrated that the input output linearization control law is the nonlinear version of the parametric open plus closed loop control law.

虚拟现实在实验动物行为分析中的应用进展

虚拟现实(virtual reality,VR)是一种通过计算机进行场景模拟的新兴技术,近年来已经成为动物行为分析的可靠工具。动物行为对动物生存至关重要。动物行为分析为遗传学、生态学、神经科学、经济学以及机器人科学等领域的科技进步提供了有用信息。动物行为分析可分为刺激独立于动物对刺激的反应的开环研究,以及刺激根据动物的实时运动进行调整的闭环研究。本文首先梳理了动物行为分析的起源、概念和应用领域,回顾了传统技术条件下以视觉刺激为代表的动物行为开环研究的不足;然后以视觉、嗅觉、触觉、听觉刺激为例,分析了虚拟现实技术条件下的动物行为分析系统能够将精确的实验控制与复杂的实验动物行为相结合的可行性,完成了真实物理世界的实验方法无法实现的闭环研究;最后对虚拟现实发展为高级模拟及虚拟动物的前景进行了展望。

A Design of a PID Self-Tuning Controller Using LabVIEW

In this paper a trial has been made to design a simple self-tuning LabVIEW-based PID controller. The controller uses an open-loop relay test, calculates the tuned parameters in an open loop mode of operation before it updates controller parameters and runs the process as a closed-loop system. The controller reacts on a persistent offset error value as a result of load disturbance or a set point change. Practical results show that such a controller may be recommended to control a variety of industrial processes. A GUI was developed to facilitate control-mode selection, the setting of controller parameters, and the display of control system variables. GUI makes it possible to put the controller in manual or self-tuning mode.

Signal averaging for noise reduction in anesthesia monitoring and control with communication channels

This paper investigates impact of noise and signal averaging on patient control in anesthesia applications, especially in networked control system settings such as wireless connected systems, sensor networks, local area networks, or tele-medicine over a wide area network. Such systems involve communication channels which introduce noises due to quantization, channel noises, and have limited communication bandwidth resources. Usually signal averaging can be used effectively in reducing noise effects when remote monitoring and diagnosis are involved. However, when feedback is intended, we show that signal averaging will lose its utility substantially. To explain this phenomenon, we analyze stability margins under signal averaging and derive some optimal strategies for selecting window sizes. A typical case of anesthe-sia depth control problems is used in this development.

具有丢包补偿的GORC-PID算法无线温度控制系统

对于工业过程控制中有线控制存在的布线困难、可拓展性差、维护成本高等问题,本文设计并开发了具有丢包补偿GORC-PID(generalized open-loop response control-PID)算法的无线温度控制系统。以工业上通用的WirelessHART为标准协议,使用无线硬件设备搭建无线通信网络,替代有线通信方式,并以监视与控制通用系统(monitor and control generated system, MCGS)组态软件为控制平台,采用改进的广义开环响应控制(generalized open-loop response control, GORC)与PID控制相结合的控制算法,通过构建的具有丢包补偿的Smith预估器对丢包数据进行估计,得出补偿的估计值,并参与GORC滚动优化中,来实现对温度的实时监测与控制。以高温炉作为研究对象进行实验,结果表明所设计的无线温度控制系统不仅可以有效解决有线过程控制中存在的问题,而且可以解决无线通信过程中的丢包、迟滞等问题,具有良好的工业价值。

Load Distribution of Base Stations in User-Centric Heterogeneous UDN

In ultra-dense networks(UDN),multiple association can be regarded as a user-centric pattern in which a user can be served by multiple base stations(BSs).The data rate and quality of service can be improved.However,BSs in user-centric paradigm are required to serve more users due to this multiple association scheme.The improvement of system performance may be limited by the improving load of BSs.In this letter,we develope an analytical framework for the load distribution of BSs in heterogeneous user-centric UDN.Based on open loop power control(OLPC),a user-centric scheme is considered in which the clustered serving BSs can provide given signal to interference plus noise ratio(SINR)for any typical user.As for any BS in different tiers,by leveraging stochastic geometry,we derive the Probability Mass Function(PMF)of the number of the served users,the Cumulative Distribution Function(CDF)of total power consumption,and the CDF bounds of downlink sum data rate.The accuracy of the theoretical analysis is validated by numerical simulations,and the effect the system parameters on the load of BSs is also presented.

Two-stage open-loop velocity compensating method applied to multi-mass elastic transmission system

In this paper, a novel vibration-suppression open-loop control method for multi-mass system is proposed, which uses two-stage velocity compensating algorithm and fuzzy I ＋ P control- ler. This compensating method is based on model-based control theory in order to provide a damp- ing effect on the system mechanical part. The mathematical model of multi-mass system is built and reduced to estimate the velocities of masses. The velocity difference between adjacent masses is cal- culated dynamically. A 3-mass system is regarded as the composition of two 2-mass systems in order to realize the two-stage compensating algorithm. Instead of using a typical PI controller in the velocity compensating loop, a fuzzy I ＋ P controller is designed and its input variables are decided according to their impact on the system, which is different from the conventional fuzzy PID controller designing rules. Simulations and experimental results show that the proposed veloc- ity compensating method is effective in suppressing vibration on a 3-mass system and it has a better performance when the designed fuzzy I ＋ P controller is utilized in the control system.

基于性能试验的实验室排风柜变风量控制系统研究

通过试验的方法,对目前3种最常用的排风柜变风量控制方式的面风速、响应时间、稳态时间及示踪气体泄漏率等性能进行研究,并对试验数据进行对比和分析,结果表明,3种不同控制方式均能很好地控制排风柜面风速,但在响应时间、稳态时间及示踪气体泄漏率方面存在明显差异。“位移传感器与文丘里阀”组合变风量控制系统的综合性能较“位移传感器与文丘里蝶阀”组合变风量控制系统更优,柜内污染物泄漏浓度更低。“面风速传感器与蝶阀”组合变风量控制系统的响应时间和稳态时间最长,柜内污染物泄漏风险最高。

带补偿的电动燃油泵流量控制研究

电动燃油泵作为多电发动机的主要控制部件,控制其快速准确地按需供油对发动机的可靠运行有着重要影响。以齿轮式电动燃油泵为研究对象,根据电动燃油泵流量与转速、进出口压差的关系,提出了基于压差补偿的开环控制方案,基于流量反馈的闭环控制方案,带压差前馈补偿的复合控制方案。通过建立电动燃油泵流量控制系统的AMESim/Matlab模型,分析了控制方案的稳态特性与动态特性。基于上述方案搭建了试验台,通过滚动测周法获得涡轮流量计的高精度实时流量,进行了流量控制试验。试验结果表明带压差前馈补偿的复合控制方案的稳态误差≯0.8%,流量波动≯1.2%,调节时间为1.44s,稳态特性和动态特性均可以满足发动机的控制需求。

Temperature Insensitive Open Loop Attenuation Control of a Liquid Crystal Based VOA

A patent pending open-loop liquid crystal based variable optical attenuator is introduced. The temperature dependent performance is compensated through electric monitoring and adjustment utilizing liquid crystal's opto-electronic properties.

水轮机监控系统导叶开度分段开环控制结构和方法研究

针对水轮发电机组在开度模式功率闭环控制方式下,导叶开度和有功功率调节速度慢,调节过程易受水锤反作用和机组惯性作用的影响问题,逐步深入优化研究,先后提出一种基于水轮机监控系统开度模式的导叶开度开环和分段开环控制方法。阐述了水轮机在开度模式下导叶开度开环和分段开环控制的结构模型和控制原理,并利用matlab对开度模式下3种导叶开度控制方法进行建模仿真。对仿真结果进行对比分析发现,水轮机监控系统开度模式导叶开度模拟量分段开环控制方法性能最佳,它既有开环控制快速的特点,又有分段开环控制超调量小的优势,能有效解决水轮发电机组在导叶开度和有功功率调节过程中出现的水锤反作用和机组惯性作用问题,从而保证在负荷调整过程中机组和电网的安全稳定优质运行。

步进电机控制系统建模及加减速曲线优化

为了优化步进电机开环控制系统,对其加减速曲线的控制性能进行了研究。以步进电机运行原理为基础,建立了两相混合式步进电机开环控制系统仿真模型,设计了一种与电机矩频特性更为符合且可以用于实时在线计算的抛物线型加减速曲线算法,并与典型的匀加减速曲线算法、指数型加减速曲线算法进行了仿真比较分析,最后进行了实验验证。仿真和实验结果均表明,在相同的控制周期内,抛物线型加减速曲线的最大无失步转动角度有了显著提高,同时其中间过程的位置跟踪误差和平衡位置处的残余振荡误差也较小。抛物线型加减速曲线具有更快速的动态响应能力,已在某相控阵列天线的单元相位控制中得到了应用。

步进电机控制系统建模及运行曲线仿真

为了优化开环情况下步进电机的控制,研究运行曲线和传动刚度对步进电机开环控制系统运动情况的影响。依据步进电机运行原理和系统动力学特性,建立控制系统数学模型。设计一种基于正矢函数,高阶平滑的加减速曲线,并与常见的匀加减速曲线和指数型加减速曲线进行了比较仿真。仿真结果表明正矢型加减速曲线能够更好地抑制运动过程中的冲击,减小终点位置的残余振动幅度。该控制方式适用于对运动精度和稳定性有较高要求的场合,在分幅式航空相机的摆扫控制中得到了成功的应用。

螺旋天线步进电机控制系统仿真及运行曲线优化

为实现机械相控阵列天线的波束扫描,采用步进电机驱动螺旋天线单元转动来达到预定的辐射相位。为了优化步进电机的开环控制,研究运行曲线对步进电机控制性能的影响,提高步进电机控制速度和精度。根据步进电机及控制系统的工作原理,建立了基于Simulink的步进电机开环控制系统仿真模型,并在此基础上对梯形和抛物线两种运行曲线进行了仿真研究。仿真结果表明,该仿真模型能精确实现两种运行曲线对步进电机的控制,在100 ms的控制周期内,采用梯形运行曲线步进电机的最大无失步转动角度能够达到270°,而采用抛物线运行曲线时其转动角度能够达到360°,抛物线运行曲线在开环控制系统中具有更高的控制速度。

基于DSP的定日镜跟踪控制系统研究

研制了一种用于塔式太阳能热发电站中定日镜的新型跟踪控制系统,该系统采用开-闭环结合的控制方式,以DSP2812为控制器,并针对定日镜谐波传动机构在控制过程中其参数在一定范围内具有'自相似性'的特性,系统采用了复合式分段控制算法,即:在开环时输出脉冲常量快速定位,在闭环粗调时采用增量式数字PID算法,在闭环精调时利用分形修正的PID算法,最终实现定日镜的精准跟踪。经测试表明,该系统跟踪精度优于3.5mrad,25度阶跃响应常数小于103ms,超调量小于3.2%,半振荡次数小于2次。该文主要成果已在国家863计划重点项目示范基地中经过现场测试检验。

对地观测高分辨率 TDICCD 相机调焦控制系统设计

本文详细介绍了一种基于卫星平台的对地观测高分辨率空间TDICCD相机调焦控制系统的设计与实现。针对相机轨道标称值为644.6 km的太阳同步轨道,为实现对地全色成像2 m分辨率和多光谱成像8 m分辨率,推扫成像不小于100 km的地面覆盖宽度要求,采用8片TDICCD高精度交错拼接技术获得高分辨率相机焦平面,以实现对地推扫成像高分辨率和宽覆盖的要求。首先,介绍高分辨率TDICCD相机的离轴光学系统设计;然后,介绍相机调焦系统组成和TDICCD长焦平面拼接技术;最后,对相机调焦系统进行调焦精度测试,根据测试数据分析出相机调焦精度并与理论设计值进行比较分析,调焦,精度测试结果为±7.2μm(3σ),满足高分辨率TDICCD相机在轨成像需要的高精度调焦要求。