Flow control valve for pneumatic actuators using particle excitation by PZT vibrator

This paper reports a new flow control valve for pneumatic actuators that has a lightweight and simple structure and uses particle excitation by PZT vibrator. The flow control valve in this report consists of an orifice plate which has plural orifices, PZT vibrator which is adhered on the orifice plate and iron particles. The valve is normally closed, because air flow carries the particles on to the orifice and particles seal the air flow. Because the orifice plate excitation by the PZT vibrator works to make the particles away from the orifice plate, the air flows through the orifices. It is driven at resonance mode and can be used as a variable speed controller for pneumatic actuators. The new flow control valve avoids the stopping shock of pneumatic actuators at the stroke ends while retaining the advantages of pneumatic actuators.     

A novel intelligent controller for combating stiction in pneumatic control valves

Pneumatic control valve introduces limit cycles in process variables due to stiction nonlinearity. In this paper a novel stiction combating intelligent controller (SCIC) based on fuzzy logic has been proposed. The proposed technique reduces the complexity of the overall control scheme as it does not require any additional compensator. The SCIC controller is a variable gain fuzzy Proportional Integral (PI) controller making use of Takagi-Sugeno (TS) scheme. The performance of the SCIC controller has been investigated and compared with conventional PI controller on a laboratory scale flow process. SCIC controller outperformed PI controller and provided promising performance with lesser aggressive stem movement.     

Design and performance of speculative flow control for high-radix datacenter interconnect switches

High-radix switches are desirable building blocks for large computer interconnection networks, because they are more suitable to convert chip I/O bandwidth into low latency and low cost than low-radix switches [J. Kim, W.J. Dally, B. Towles, A.K. Gupta, Microarchitecture of a high-radix router, in: Proc. ISCA 2005, Madison, WI, 2005]. Unfortunately, most existing switch architectures do not scale well to a large number of ports, for example, the complexity of the buffered crossbar architecture scales quadratically with the number of ports. Compounded with support for long round-trip times and many virtual channels, the overall buffer requirements limit the feasibility of such switches to modest port counts. Compromising on the buffer sizing leads to a drastic increase in latency and reduction in throughput, as long as traditional credit flow control is employed at the link level. We propose a novel link-level flow control protocol that enables high-performance scalable switches that are based on the increasingly popular buffered crossbar architecture, to scale to higher port counts without sacrificing performance. By combining credited and speculative transmission, this scheme achieves reliable delivery, low latency, and high throughput, even with crosspoint buffers that are significantly smaller than the round-trip time. The proposed scheme substantially reduces message latency and improves throughput of partially buffered crossbar switches loaded with synthetic uniform and non-uniform bursty traffic. Moreover, simulations replaying traces of several typical MPI applications demonstrate communication speedup factors of 2 to 10 times.     

Single-step replicable microfluidic check valve for rectifying and sensing low Reynolds number flow

This paper presents a new microfluidic check valve well suited for low Reynolds number flow rate sensing, micropump flow rectification, and flow control in lab-on-a-chip devices. The valve uses coupling between fluid movement in a channel and an elastomeric column (flap) suspended in the fluid path to generate a strong anisotropic flow resistance. Soft lithography-based molding techniques were used to fabricate the valve, allowing for a low-cost, single-step fabrication process. Three valves—having heights of 25, 50, and 75 μm, respectively—were fabricated and experimentally evaluated; the best of them demonstrated a maximum fluidic diodicity of 4.6 at a Reynolds number of 12.6 and a significant diodicity of 1.6 at the low Reynolds number of 0.7. The valve’s notable low Reynolds number response was realized by adopting a design methodology that balances the stiffness of the elastomer flap and adhesion forces between the flap and its seat. A pair of elastomer check valves integrated with a miniature membrane actuator demonstrated a flow rectification efficiency of 29.8%. The valve’s other notable features include a wide bandwidth response, the ability to admit particles without becoming jammed, and flow rate sensing capability based on optical flap displacement measurements.     

A practical control strategy for servo-pneumatic actuator systems

A practical control strategy with a simple controller structure is proposed for servo-pneumatic cylinder actuator systems. Theoretical analysis reveals that the acceleration of the piston indirectly represents the cylinder chamber pressure difference so it is possible to employ acceleration feedback instead of pressure feedback in the construction of servo-pneumatic actuator control systems. The main features of the control strategy developed in the paper are (1) using acceleration feedback to improve the stability of the system; and (2) introducing time-delay minimisation and optimised null offset compensation to address the problem of time delay and dead zone, which are mainly caused by the compressibility of air and friction. The experimental studies have been conducted using an asymmetric pneumatic cylinder system and the results show that the system performance has been much improved when compared with a conventional PID controller.     

基于HHT的控制阀气密性故障诊断研究

以气动薄膜控制阀气室气密性故障为研究对象,首先对控制阀阀位动作信号进行希尔伯特-黄变换,通过经验模态分解方法检测故障的发生及发生时刻;其次分析了其各阶模态及其能量占比特性,获得了气动控制阀气室气密性故障类别和强度的在线诊断。通过模型仿真和实体阀实验验证了本文提出的检测及诊断方法的有效性和实用性。研究首次将希尔伯特黄变换信号分析方法引入到非周期、非平稳过程故障诊断中来,完整的实现了气动控制阀气室气密性故障的检测、诊断和强度识别。     

低功耗射频智能锁控阀设计

以MSP430F4152为核心,结合T5557射频卡和125kHz射频技术实现了供暖管道阀门的智能控制。同时,介绍了T5557射频卡的结构及工作原理,提出一种以分立器件实现射频卡读写的设计方法。调试结果验证了方案的可行性和系统的稳定性,该设计可广泛应用于供暖系统中。     

基于L9352B的电磁阀控制电路设计与实现

提出了一种基于ARM与集成驱动芯片L9352B的控制方法,该方法通过ARM的输入和输出信号,经隔离后送入集成驱动芯片,对电磁阀进行控制和检测。集成驱动芯片除了可以驱动4通道电感负载外,还可以监测每个通道是否出现诸如短路、开路、过载、过热及时钟丢失等故障。然后对电磁阀的硬件电路进行详细的设计。实际工程应用的结果表明此电路设计可行,具有可靠性高、成本低、驱动能力强、故障监测功能多的优点。     

汽轮发电机主汽门开度非线性鲁棒控制

由于外界干扰以及各种故障的影响, 电力系统的结构并不是不变的, 因此其中的一些重要参数, 如输电线路电抗等, 总是包含某种不确定性. 针对含有参数不确定性的汽轮机调速系统, 使用自适应逆推方法及Lyapunov方法设计了非线性鲁棒汽门控制器, 基于该方法的设计, 设计过程系统、简明, 且不必对原系统进行线性化, 通过对单机无穷大系统的仿真表明了该控制器的有效性.     

摩托车可变配气正时机构自动控制装置的设计

介绍了一种基于双凸轮结构的摩托车发动机可变配气正时(VVT)机构自动控制装置。简述了该装置的控制策略、工作原理和硬件设计,并给出了具体的程序设计流程图。该装置具有制造成本低、机构紧凑、控制精度高和可靠性好的优点,广泛适用于各中小排量摩托车发动机VVT机构。     

Iterative learning control of a fully flexible valve actuation system for non-throttled engine load control

This paper presents the application of a fully flexible valve actuation system for non-throttled load control of an internal combustion engine. A novel camless valve actuation system with a unique hydro-mechanical internal feedback mechanism which simplifies the external control design is first introduced. All the critical parameters describing the engine valve event, i.e., lift, timing, duration and seating velocity, can be continuously varied by controlling the triggering timings of three two-state valves. Initial testing of a prototype experimental setup reveals that the performance of the system (transient tracking and steady-state variability) is influenced purely by the state of the system when the internal feedback mechanism is activated. This feature motivates the development of a cycle-to-cycle learning-based external control for activating the internal feedback mechanism based on the desired valve profile characteristics and the system state. To verify the proposed control methodology, it is implemented on the experimental system to track reference trajectories for the various valve event parameters corresponding to the non-throttled load control of an engine during the U.S. Federal Test Procedure (FTP) urban driving cycle. Vehicle load demand analysis is used to compute the desired engine speed and torque requirements. Detailed dynamic valve flow simulations assuming full flexibility of the engine valve event parameters help to calculate the required trajectory of all these parameters to satisfy the speed and torque requirements without the use of a throttle. The experimental results show that the proposed framework, i.e., the valve actuation system and the external control methodology, is able to provide excellent performance even during the most aggressive transient operating conditions.     

Design and experimental testing of an optimization-based flow control algorithm for Energy Harvesting Wireless Sensor Networks

In this paper a distributed flow control law is proposed to maximize throughput and to minimize energy consumption in Energy Harvesting Wireless Sensor Networks (EH-WSNs). We preliminary recast the control problem in terms of primal–dual optimization one taking into account the bandwidth and energy autonomy node constraint. Then, we devise a distributed flow rate control implemented at each node that allows the overall network to converge to the optimal solution of the original problem. The closed loop EH-WSN stability and convergence to the optimal equilibrium are proven. The effectiveness of the proposed control law in terms of throughput and network lifetime performance is experimentally validated by a small representative EH-WSN. The experimental results are in a good agreement with the theoretical ones.     

进气道流量调节阀控制装置设计

由于飞机发动机进气道试验中空气流量需精确控制,需要采用一种响应迅速,且较为容易实现计算机精确控制的机械电子系统。该气道流量调节控制装置采用C8051F021单片机与易于单片机控制的步进电机来实现系统控制功能,用5×4的键盘作为输人来对电机的状态进行控制,键盘输入的数据送至单片机,并用数码管显示输入的行程和整个系统的运行工况与位移传感器的测量值,单片机输出信号控制步进电机的运行;系统设置了串口通信,通过MAX232接口电路实现控制系统与上位机的数据通信,通过上位机实现对进气道流量的控制。     

微光机电陀螺微致动器设计与有限元分析

提出了一种锆钛酸铅(PZT)薄膜微致动器的结构模型。该致动器采用高d33特性的压电陶瓷材料,用于对空间谐振式微光机电(MOEMS)陀螺微镜进行位移和角度的精确定位。建立了该致动器的简化模型并利用有限元方法分析其驱动能力。结果显示,当采用双层结构的PZT薄膜微致动器时,在外加电压50V作用下,环形PZT位移控制器中心位移可达到0.345μm;十字形角度控制器偏转角度可达3.29″,增加PZT薄膜的层数可以进一步增加致动器对微镜位移和角度的控制能力。通过对仿真结果进行分析可以得出结论,选用多层PZT薄膜材料制成的微致动器能够满足调整微镜位移和角度所需的范围和精度要求。     

A new adaptive backstepping method for nonlinear control of turbine main steam valve

A new approach for nonlinear adaptive control of turbine main steam valve is developed. In comparison with the existing controller based on ＂classical＂ adaptive backstepping, this method does not follow the classical certaintyequivalence principle in the design of adaptive control law. We introduce this approach, for the first time, to power systems and present a novel parameter estimator and dynamic feedback controller for a single machine infinite bus （SMIB） system with steam valve control. This system contains unknown parameters such as reactance of transmission lines. Besides preserving useful nonlinearities and the real-time estimation of uncertain parameters, the proposed approach possesses better performances with respect to the response of the system and the speed of adaptation. The simulation results demonstrate that the proposed approach is better than the design based on ＂classical＂ adaptive backstepping in terms of properties of stability and parameter estimation, and recovers the performance of the ＂full-information＂ controller. Hence, the proposed method provides an alternative for engineers in applications.     

某型连续式跨声速风洞阀门控制系统设计

针对某型风洞阀门数目较多,位置分散,空间较少等问题,为避免"硬接线"集中控制方式带来的诸多问题,采用一套PLC系统完成对各类阀门的控制,并由上位机通过PROFINET网络进行调度与指挥,实现远程控制;对阀门阀芯定位精度与流量调节精度的关系进行了推算,并据此选定了阀门电动执行机构型号;在已调试完成的某风洞的吹风试验表明,通过该方法所设计的阀门控制系统流量调节精度可达到0.1%。     

呼吸机比例阀的控制与仿真

比例阀是呼吸机吸气模块中负责流量控制的重要组件,为了研究比例阀的特性和提高呼吸机吸气模块的流量跟踪效果,推导了比例阀阀芯位移与流量之间的关系,构建了比例阀的被控对象模型并采用S—函数在Simulink中实现了该模型;对模型进行简单的输入控制可以获得比例阀的瞬态特征和稳态特征,对模型输入采用PID控制和模糊PID控制方法均能够提高比例阀的响应速度;在两种控制方法中采用一致参数,分别在Simulink仿真和实验条件下对比两种方法的流量跟踪效果,可以验证相较于固定参数的PID控制方法,模糊PID控制方法更能有效降低流量的超调量从而保持气路中流量的稳定.     

An improved valve stiction simulation model based on ISA standard tests

The Choudhury valve model is a widely adopted data-driven model to study the behaviour of valve stiction. A recent study (Garcia, 2008) revealed that valve stiction simulation based on Choudhury’s simulation model (Choudhury, Thornhill, & Shah, 2005) fails to pass eight out of fifteen Industry Standard Architecture (ISA) standard tests (ISA, 2000, ISA, 2006) for real control valves. In this study, the ISA testing results are further elaborated for this model. It is found that three minor deficiencies lead to the discrepancies between the Choudhury Model outputs and the expected ones when (i) the valve input signal changes the direction of travel, (ii) the initial stem position does not stay on the working curves l₁ and l₂, and (iii) the valve input signal changes in a ramp–pause–ramp manner. To address the above deficiencies, an improved version of the Choudhury Model, termed as XCH Model, is proposed. Assessments along with the ISA standards presented by Garcia (2008) demonstrate the proposed XCH Model passes all the ISA standard tests and thus provides a more realistic simulation of a real industrial valve being able to exhibit stiction behaviour.     

球阀PID控制研究

通过建立球阀角度与过流面积非线性关系,解决PID过程控制球阀角度时引入的周期干扰,在CO2热泵的水温控制中获得较好控制效果。     

A differential control method for the proportional directional valve

For the proportional directional valve controlled by two proportional solenoids, the normal control method （NCM） energizes only one solenoid at a time. The performance of the valve is greatly influenced by the nonlinearity of the proportional solenoid, such as dead zone and low force gain with a small current, and this effect cannot be eliminated by a simple dead-zone current compensation. To avoid this disadvantage, we propose the differential control method （DCM）. By employing DCM, the controller outputs differential signals to simultaneously energize both solenoids of the proportional valve, and the operating point is found by analyzing the force output of the two solenoids to make a minimum variation of the current force gain. The comparisons of the valve response characteristics are made between NCM and DCM by nonlinear dynamic simulation and experiments. Simulation and experimental results show that by using DCM, the frequency response of the valve is greatly enhanced, especially when the input is small, which means that the dynamic characteristics of the proportional valve are improved.