基于超声波测距的液位自动控制系统

本文介绍了一个基于超声波物位测量原理的液位自动控制系统,它能实时测量并显示液位;可以根据预设液位对容器中的液体进行补给操作.系统通过超声波测速温度补偿对液位测量值进行修正;通过"软件滤波"对测量数据进行修正,使液位控制误差小于2cm.     

基于LabVIEW的电磁波峰焊非接触液位测量系统

在电磁波峰焊接过程中,液位波动大小是一个非常重要的参数,如果锡液液位波动大,易造成虚焊等问题,对电磁波峰焊液位波动的实时监控显得尤为重要.通过使用液位测量模块、Arduino控制器及计算机组成的非接触液位测量系统对电磁波峰焊的锡液液位波动进行测量,结合虚拟仪器软件LabVlEW将液位波动数值和液位波动曲线可以形象地显示出来,同时对液位波动范围进行预先设置,当超出液位波动设置的最大值或者低于液位波动设置的最小值就会给出警报并及时反馈,从而提高焊接质量.通过实验测量与验证,实验测量的液位波动程度与预期值相符合,且很平稳.     

基于单片机的油舱液位在线测量装置的设计

论述了船舶油舱液位在线测量的必要性,并对液位在线测量方法进行了分析比较,设计出以单片机为核心的新型油舱液位在线测量装置,实现了船舶液位的精确测量。     

一种基于单片机的液位测控系统的研究

介绍了一种以STC89C51单片机为测控核心,通过电容传感器对液位进行测量和控制的系统。通过对现场液位状况分析,采用电容传感器对现场液位物理量进行检测,然后将检测到的信息通过处理电路,传送到单片机,利用计算机技术,实时处理现场采集的液位数据信号。通过本系统的应用,达到了对工控液位间接测量、自动控制和管理的目的。     

霍尔液位测量传感器的设计与应用

针对电阻式液位传感器的不足之处,我们设计了一种利用霍尔器件作为传感元件的液位测量传感器,对霍尔式液位传感器的设计做了简单的介绍,对霍尔式液位传感器的工作过程和工作原理进行了讨论。     

电容式液位测量系统的设计

电容式液位测量系统是基于改变介电常数时,电容器的电容量变化的原理来测量液位的。利用电容式传感器,ADC0809,8031,2764,8155单片机和LED数码管等组成测量系统,对煤油的液位进行测量。它具有设定液位、显示当前液位和声光报警的功能。实验表明:该系统能对导电液体的液位测量,并具有结构简单、成本低、性能稳定等优点。     

四电极污水液位测量方法研究

根据污水导电的特点,利用与污水相接触的电极进行液位测量,其方法简单实用,具有的优点明显.由于污水的温度和成分不固定,其电导率是变化的,故利用二电极直接测量液体电导来进行液位测量方法不能适用于对污水液位的测量.针对这一问题,提出了一种四电极液位测量方法.通过理论分析和实验验证此方法测量液位不受被测液体电导率变化影响,可用于对温度和成分不固定的污水液位进行测量.     

一种基于传感器的小区水管道监测系统

正本发明公开了一种基于传感器的小区水管道监测系统,包括设置于水管道上端的无线液位传感器和控制平台,无线液位传感器与控制平台相连,将检测到的液位信息发送到控制平台;控制平台包括微处理器以及分别与微处理器相连的显示屏、报警装置。本发明利用无线液位传感器对下水管道的液位进行检测,可以将无线液位传感器设置到下水管道的任何位置,检测的范围变得很大;无线液位传感器与控制平台之间通过无线传输,传输的距离远,一个控制平台可以监控多个无线传感器,可以对多条管道进行监控。     

基于STM32的无线分布式液位采集系统设计

采用无线分布式组网技术开发了一种可移动液位监测系统。以STM32F107单片机为核心,运用超声波液位传感器对物位进行测量,通过C322WiFi模块进行数据传输。系统中拥有能够对采样数据进行处理、显示与储存的监控软件平台系统,实现对移动罐工作状态、工作地点以及物料液位信息的实时监测。实验证明,整套系统便捷、实用,能够满足对移动罐内物料液位的监测需求。     

双法兰差压式变送器在过滤分离器液位测量中的稳定性分析

通过对双法兰变送器在过滤分离器液位测量中一直呈现测量不准确及波动无常的原因分析,该文提出了在对特定工艺设备进行液位测量时,采用干簧管液位远传变送器测量的方法,以削弱液位测量易受介质流速和介质密度不稳定的影响,有助于在工程设计过程中提高液位测量的稳定性。     

基于单片机的LCD实时曲线显示的设计

文章介绍了单片机液位控制系统中LCMl28645ZK液晶显示器显示动态实时曲线的设计方法。采用C51编写系统应用程序,不仅实现了液位系统的自动控制,还能够满足对控制字符、数据以及曲线的实时动态显示,成功应用于液位控制系统中,人机交互效果良好。     

基于意识-情感-智能三位一体的煤矿供液过程控制

为保障煤矿工作面液压支架安全高效运行,提高供液系统智能化水平,通过分析供液系统多层智能控制目标,借鉴高等人工智能原理中的意识-情感-智能三位一体思想,设计并构建了供液系统的智能控制模型。针对现有自动化水平的供液基础控制技术、欠成熟智能化水平的稳压供液预测技术和成熟智能化水平的智能供液控制技术,分别设计基础意识模块、情感模块和理智与决策模块的功能结构,并将其嵌入智能供液系统,实现供液过程智能控制。上述系统在潞安集团王庄煤矿8110综采工作面进行了工业性试验,并取得了理想的控制效果。     

智能PID算法在远程液位控制系统中的应用

本文介绍了利用可编程序控制器(PLC)实现的远程液位自动控制系统，详细论述了智能PID算法的控制规则，给出了由PLC完成其控制策略的硬件配置和软件实现方法。     

Intelligent distributed and supervised flow control methodology for production systems

This paper deals with the development of an intelligent distributed and supervised control approach for high-volume production systems, in which the flow of parts can be approximated by a continuous (fluid) model. The proposed approach is based on the decomposition of the production system into elementary modules in order to reduce the control design computational complexity. In this context, a two levels control structure is proposed. At the local level, a surplus-based principle is adopted to regulate the production flow for each module according to the distributed structure. The proposed control methodology decides how to adjust the production rate in order to avoid system overloading and eliminate machine starvation or blocking. In this context, the local control law is synthesized by using the Takagi–Sugeno fuzzy systems. At the high level, a supervisory controller is designed to improve the overall system performances. A supervisor provides an additive component for each local controller when the overall system performances deviate from their acceptable domains (degraded mode). This is done by combining both local and global information into a unified formalism by using aggregation operators and according to fuzzy interval representation of the desired objectives. Finally, the feasibility of the proposed methodology is validated with simulation examples.     

Repetitive control of tubular heat exchangers

Effective operation of heat exchangers involves optimum control of the fluid outlet temperature. Several ideas have been proposed in the literature to cope with intrinsic resonance dynamics aimed at widening the bandwidth of the closed-loop system to achieve fast, well-damped responses in controlling the outlet fluid temperature by means of the steam temperature. This is also the main purpose of this article, in which the use of a repetitive control scheme is proposed to take resonance dynamics into account when residence time is variable, as in this case the control variable is the fluid flow rate and not the steam temperature. The scheme is based on a model of the tubular heat exchanger dynamics in which the explicit terms of resonance are cancelled out by the controller. Simulation results are provided both for a typical tubular heat exchanger and for a special sort of heat exchanger, the distributed collector field of a solar power plant.     

Optimal control of a solar collector loop using a distributed-lumped model

This paper considers the optimal control of a solar collector loop described by a bilinear distributed parameter model for the collector fluid temperature and a bilinear lumped parameter model for the storage fluid temperature. The objective is to control the collector fluid velocity so as to maximize the net energy collected over a fixed time period. Necessary conditions for optimality, given by a set of equations whose solution yields the optimal control, are derived. It is shown that the optimal control is an open-loop, bang-bang control which depends on two terms: a measurable quantity which depends on the state of the collector fluid, and a quantity which depends on a future knowledge of the weather data. It is also shown that for the case in which only two switches occur during the period of operation, the optimal control depends only on the temperature difference across the collector. Thus, one can construct a feedback on/off controller for the system provided that it is known a priori that only two switches will occur during the time interval under consideration.     

喂料机提升皮带调速的模糊控制

常规喂料机提升带调速控制是简单的双速控制，较难满足生产线平稳生产的要求；为了解决这一问题，通过对喂料机料位控制过程的分析，介绍了模糊控制技术在喂料机料位控制中的应用和模糊规则的建立，通过仿真及其实际使用，应用效果明显，提高了整条生产流水线平稳持续生产的水平；同时也为模糊控制在PLC的应用上做一定的探索与研究。     

Boundary control of a parallel-flow heat exchanger by input–output linearization

A design of the control of the internal fluid temperature at the outlet of a parallel-flow heat exchanger by manipulating the inlet external fluid temperature is proposed. The dynamic model of the heat exchanger is given by two partial differential equations that are used without spatial discretization to design the control law. Based on nonlinear control, a state-feedback law that ensures a desired performance of a measured output defined as the spatial weighted average temperature of the internal fluid is derived. Then, in order to control the outlet internal fluid temperature, a control strategy is proposed where an external controller is introduced to provide the set point of the considered measured output by taking as input the error between the outlet internal fluid temperature and its desired set point. As the designed control law is a state feedback of distributed nature, for practical application, a Kalman filter is used to reconstruct the entire state of the system from the measurements of the outlet fluids temperatures. The closed-loop system is shown to be exponentially stable. The validity of the proposed control design is examined in simulation by considering the tracking and perturbation rejection problems.     

锅炉汽包水位控制系统的研究

锅炉汽包水位是一种非线性、时变大、强耦合的多变量系统。在建直了锅炉汽包水位调节对象的数学模型的基础上，利用模糊控制理论设计锅炉水位控制系统，运用模糊控制与PID控制分别对汽包水位进行控制。介绍了控制器的设计和仿真分析，并应用MATLAB软件对汽包水位控制系统进行验证和仿真，给出了模糊控制方法与传统方法的比较结果，表明了模糊控制明显地改善了汽包水位控制系统的静、动态特性，从而实现了对锅炉汽包水位的最件实时控制。     

精细化工过程控制技术的发展动向

精细化工产品的市场需求快速多变,产品更新换代快,使得精细化工生产过程一般采取小批量、多品种生产,生产过程多为间歇或半连续过程,时变性、非线性强,生产过程的工艺流程复杂,操作步骤繁杂,劳动强度大;精细化工生产过程的工艺介质多为有一定毒性、腐蚀性和易燃易爆性的化学品,过程运行危险性大;这些特点使得精细化工生产过程更难以控制,综合自动化水平普遍较低.为了提高精细化工生产过程的综合自动化水平,需根据精细化工生产过程的特点及其控制需求,进行精细化工生产过程控制技术的研究和应用.目前,精细化工过程控制技术的主要发展动向为:从常规仪表控制向计算机控制、集散式控制系统(Distributed Control System,DCS)控制发展;从简单的顺序控制、程序控制向基于ISA SP88间歇过程控制标准的自动批量生产控制发展;从人工控制、常规PID控制向先进的批次-批次迭代学习优化控制发展;从简单工艺参数的控制向生产工况和生产质量的综合性统计过程控制发展;从简单的工艺参数越限连锁报警向综合性安全保护控制和在线实时非正常工况管理发展.