HYBRID CONTROL OF HYDRAULIC PRESS MACHINE BASED ON ROBUST CONTROL

A robust control algorithm is proposed to focus on the non-linearity and variables of the hydraulic press machine with the proportional vatve. The proposed robust controller does not need to design stable compensator in advance, which is simple in design and has large scope of uncertainty applications. The feedback gains of the proposed robust controller are small, so it is easily implemented in engineering applications. The theoretical and experimental research on the position and speed control of the hydraulic press machine is carried out. The control requirements of the hydraulic press machine during the working process are met in the position and speed at the same time. Experimental results show that the proposed controller has better robustness subject to load variables and adaptability of parameter variations of the hydraulic press machine with the proportional valve.

IMPROVE THE KINETIC PERFORMANCE OF THE PUMP CONTROLLED CLAMPING UNIT IN PLASTIC INJECTION MOLDING MACHINE WITH ADAPTIVE CONTROL STRATEGY

The kinetic characteristics of the clamping unit of plastic injection molding machine that is controlled by close loop with newly developed double speed variable pump unit are investigated. Considering the wide variation of the cylinder equivalent mass caused by the transmission ratio of clamping unit and the severe instantaneous impact force acted on the cylinder during the mold closing and opening process, an adaptive control principle of parameter and structure is proposed to improve its kinetic performance. The adaptive correlation between the acceleration feedback gain and the variable mass is derived. The pressure differential feedback is introduced to improve the dynamic performance in the case of small inertia and heavy impact load. The adaptation of sum pressure to load is used to reduce the energy loss of the system. The research results are verified by the simulation and experiment, The investigation method and the conclusions are also suitable for the differential cylinder system controlled by the traditional servo pump unit.

A machine learning-based study of multifactor susceptibility and risk control of induced seismicity in unconventional reservoirs

A comprehensive dataset from 594 fracturing wells throughout the Duvernay Formation near Fox Creek, Alberta, is collected to quantify the influences of geological, geomechanical, and operational features on the distribution and magnitude of hydraulic fracturing-induced seismicity. An integrated machine learning-based investigation is conducted to systematically evaluate multiple factors that contribute to induced seismicity. Feature importance indicates that a distance to fault, a distance to basement, minimum principal stress, cumulative fluid injection, initial formation pressure, and the number of fracturing stages are among significant model predictors. Our seismicity prediction map matches the observed spatial seismicity, and the prediction model successfully guides the fracturing job size of a new well to reduce seismicity risks. This study can apply to mitigating potential seismicity risks in other seismicity-frequent regions.

Analysis and application in controlling surrounding rock of support reinforced roadway in gob-side entry with fully mechanized mining

In order to optimize gob-side entry in fully-mechanized working face in moderate-thick-coal seams, we adopt a new attempt to pack roadside by pumping ordinary concrete, which is very important for the development of gob-side entry technology. The concrete has a long initial setting time and a low initial strength. So it is difficult to control the surrounding rock. In this paper, we analyze the effect of using roadside cable to reinforce supporting in gob-side entry surrounding rock controlling based on elas-tic-plastic and material mechanics knowledge. And then we propose a scheme that cable is used to reinforce roadside supporting and a single hydraulic prop is used as the temporary supporting in gob side. Using the numerical simulation software FLAC2D, we numerically simulated supporting scheme. Results of both the 2D modeling and the industrial test on No.3117 face in Jingang Mine prove that the scheme is feasible. The results show that the technology of protecting the roadway in gob-entry retained efficiently make up the deficiency of roadside packing with ordinary concrete, effectively control the roof strata and acquire a good result of retaining roadway.

Control strategy for multi-pump emulsion power station in coal mine face

Shearer and hydraulic support are matching equipments. To increase the operating speed of the shearer, the following speed of hydraulic support must be increased. This means increasing the volume of flow from emulsion power station. Analyzing the operating characteristics of hydraulic supports, the number of simultaneously operating supports is obtained by means of pressure parameter and time history at a certain time, which is a theory base for development of control system to multi-pump emulsion power station.

PRINCIPLE TO CLOSED LOOP CONTROL DIFFERENTIAL CYLINDER WITH DOUBLE SPEED VARIABLE PUMPS AND SINGLE LOOP CONTROL SIGNAL

To control the position of differential cylinder closed loop without usingany throttle elements, a flew idea that two speed variable pumps are used to compensate thenon-symmetric flow of differential cylinder is carried out. According to the leaking property of thesystem, a speed offset principle is also proposed to eliminate the cavitation and tension caused bythe leakage and condensation of oil, which makes the system be in the same state as a valvecontrolled circuit. This principle is explained theoretically and experimentally. Further therelationship that the pressures in cylinder chambers change with load and leakage, and therelationship between biasing speed and pre-load pressures in cylinder chambers are established. Theresearch has proved that the new system has similar technique features as those of controlled withservo valves, but due to the elimination of all the throttle lose the efficiency of system can beimproved greatly.

Verification of VVER-1200 NPP Simulator in Normal Operation and Reactor Coolant Pump Coast-Down Transient

Verification of operation parameters of VVER-1200 NPP Simulator installed at Nuclear Training Center, VINATOM has been performed. This simulator has been supplied for Vietnam in the framework of IAEA TC Project VIE2010 on Developing Nuclear Power Infrastructure—Phase II hosted by the Vietnam Atomic Energy Agency (VAEA). The comparison of the main parameters in nominal power operation with design data given in safety analysis report of VVER-1200/V392M as well as Ninh Thuan FSSAR is presented. In this study, the reactor coolant coast-down transient is investigated using the VVER-1200 NPP simulator. The simulated results performed in the simulator through switching off one reactor coolant pump in comparisons with experiment results performed in VVER-1000 reactor are given. The similarity between the measured and simulated results shows that the thermal hydraulic characteristics and the control protection systems are modeled in a reasonable way. A good agreement in operating parameters was found between the VVER-1200 NPP simulator and VVER-1200/V392M’s PSAR.

A method to perform prognostics in electro-hydraulic machines: the case of an independent metering controlled hydraulic crane

Remaining useful life (RUL) estimation is a topic that has gained more and more attention in the field of fluid power systems, thanks to the tremendous potentials shown for improving safety and reduced production losses. However, many challenges related to RUL estimation are not solved yet, mainly connected to the definition of the health status of each component. A prognostic method based on a data-driven methodology for hydraulic systems is here proposed to estimate the percentage of life already spent by the monitored components. The potentials of the methodology are shown considering the case of a truck-mounted hydraulic crane, for which a simulation model was available.

基于FluidSIM-Hydraulic的注塑机液压回路控制分析

基于FluidSIM-Hydraulic软件对注塑机液压回路控制系统进行分析。介绍了注塑机的结构原理,并优化设计了液压回路及电气控制系统,通过二者有效的结合成功地将模拟仿真后的模型应用到了实际生产中,取得了良好的效果。

Energy-saving and accurate motion control of a hydraulic actuator with uncertain negative loads

Pump controlled hydraulic actuators are wildly used in the aerospace industry owing to the advantages of energy-saving and integrated configurations.Negative loads may occur to actuators due to external force loads or the inertial force when the actuator decelerates significantly.Uncertain negative load working conditions may cause cavitation,actuator vibration,and even instability to the motion control if the actuator is without sufficient meter-out damping.Various types of hydraulic configuration schemes have been proposed to deal with negative loads of hydraulic actuators.However,few of them can simultaneously achieve energy saving and high control accuracy.This study proposes an energy-saving and accurate motion tracking strategy for a hydraulic actuator with uncertain negative loads.The actuator’s motion is driven by a servomotor pump,which gives full play to the advantage of energy-saving.The meter-out pressure is controlled by proportional valves to provide the optimized meter-out damping.The nonlinear adaptive robust control law is designed,which guarantees the control stability and achieve high tracking accuracy.An integrated direct/indirect adaptation law obtains satisfactory parameter estimations and model compensation for asymptotic motion tracking.Comparative experiments under different working conditions were performed to validate the advantages of the proposed control strategy.

数控机床液压系统分析与装配工艺实践

研究机床液压系统的工作原理、完善液压元件的安装工艺是机床生产和使用单位从装配细节着手提高机床稳定性等综合性能的有效途径。文章以某知名国产品牌数控车床的液压系统为研究对象,分析了该产品液压系统的组成及控制回路的工作原理,并对液压元件通用装配工艺做出了详细的规范性技术要求。通过在机床生产与维修中的实践证明,此技术规范可提高机床装配质量和综合性能的稳定性,可为机床技术从业人员掌握机床液压系统的基本知识提供一定的参考,对正确安装、调试、使用、维护和维修机床有着重要的指导意义。

基于深度神经网络的电液伺服泵控系统健康评估研究

电液伺服泵控系统具备功重比高、响应快等优点,在多领域得到广泛应用,但如何针对该系统开展更有效健康评估,进一步保障系统的安全性和可靠性成为必须面对的问题。按照明确原理、建立数学模型、建立仿真模型、仿真分析的思路针对健康评估方法开展研究,提出油液体积含气量、气隙磁密、泄漏系数3个健康评估指标并确定阈值,构建了LGA(LSTM-GRNN-ANN)深度神经网络健康评估方法并进行仿真分析,结果显示该方法准确率约为97.48%,比LSTM、GRNN健康评估方法具有更高的准确率,为继续深入开展电液伺服泵控系统健康评估的研究提供了理论支持。

基于Links-RT的数字液压风力机半实物仿真系统设计

数字液压风力机可根据风速大小使相应排量液压泵参与工作,使液压风力机在整个工作风速范围内始终保持高效。由于大型风力机不具备开展实验研究的条件,且风力机中的液压系统具有较强的非线性,为了准确研究数字液压风力机多泵切换时系统工作特性的变化规律,提出了一种基于Links-RT的数字液压风力机半实物仿真系统,并对数字液压风力机风轮特性模拟和最大功率跟踪控制进行设计。通过风速阶跃变化、恒定风速时多泵切换、渐变风速多泵切换3种工况下数字液压风力机工作特性的实时仿真测试,验证了数字液压风力机半实物仿真系统的正确有效性,为数字液压风力机的稳定运行和风能高效利用提供理论依据和技术参考。

基于曲率控制前缘的离心泵压力脉动及水力性能分析

蜗壳式离心泵作为流体输送的核心设备,压力脉动及水利性能对泵的稳定性、噪声、寿命等有重大影响。结合曲率控制前缘的设计方法,按增长率1.19%、0.47%、0.32%设计,建立前缘轴长比为0.96、2.11、3.11、4.11的蜗壳式离心泵,以SSTκ-ω模型定常计算结果为初始条件,进行κ-εRNG模型非定常分析,通过频域图分析蜗壳式离心泵压力脉动,并通过矢量云图分析水力性能。结果表明:设计的模型最佳流量为35 m 3/h,设计效率与模拟效率误差仅为2%;前缘轴长比不同,流道内压力扩散有差异;前缘轴长比为3.11时出口压力脉动偏低,低频区更易产生压力脉动;前缘轴长比为0.96时,压力脉动范围偏小,适用于一定流量范围内扬程变化较大的工况。

基于指数趋近率的液压机泵控伺服系统滑模控制

滑模控制方法具备较强鲁棒性,控制器结构也较简单,被广泛应用于泵控电液伺服液压系统上。在分析泵控系统原理的基础上,为克服传统PID控制很难抵抗较强外部干扰力的缺点,泵控伺服系统建立指数趋近律滑模控制器,建立泵控伺服系统MATLAB/Simulink仿真。研究结果表明:正弦信号跟踪下,滑模控制最大稳态跟踪误差与PID相比降低83.4%,同时控制器IMSE指标相对PID控制器发生了显著降低。该研究有助于提高液压机运行效率,对提高产品质量具有一定的指导意义。

基于IPSO优化模糊PID的液压变速器转速控制

为了提高液压变速器转速跟踪能力,开发了一种改进粒子群(IPSO)优化模糊PID控制算法。利用Matlab/Simulink分析阶跃负载信号时响应性能差异性,在HMCVT段范围内完成无级调速的控制效果。研究结果表明:负载影响下,系统扰动幅值快速降低55rad/min。受系统闭环反馈影响,在0.1s内重新跟踪输入参数,可以使HMCVT泵控系统1s时间完成马达转速跟踪的功能。本次开发的HMCVT泵控系统可以满足马达转速的准确跟踪效果,具备低超调量、高鲁棒性等优点。

基于遗传算法前馈PID控制的电液伺服泵控系统性能研究

电液伺服泵控技术在液压支架、采煤机、掘进机、挖掘机等煤矿装备中得到了广泛应用,但在复杂工况下,其动作响应性和准确性受到较大影响,需进一步提高。在数学模型的基础上建立了关键部件仿真模型和系统模型,提出了基于遗传算法的前馈PID控制策略。利用MATLAB软件进行仿真,结果显示,阶跃压力信号响应曲线的稳态误差为0.1 MPa、响应时间为0.5 s,正弦压力信号跟随曲线的最大误差为0.02 MPa,较经典PID控制缩短了响应时间,降低了误差,整体性能得到提升。

模糊自整定PID的液压马达驱动机床主轴速度控制研究

液压马达驱动机床主轴系统具有参数时变和高度非线性,传统PID控制器控制精度不高。针对液压马达驱动机床主轴系统速度控制问题,采用模糊自整定PID控制器实现液压马达驱动机床主轴系统的有效控制,并对控制效果进行仿真验证。构造了液压马达驱动机床主轴系统模型简图,建立了液压马达驱动机床主轴系统数学模型。对传统PID控制器参数,用模糊控制器进行实时整定,开发了模糊自整定PID控制器。最后,采用MATLAB对液压马达驱动机床主轴系统进行仿真。同时,与传统PID控制器的计算结果进行对比和分析。仿真结果显示:采用模糊自整定PID控制器的液压马达驱动机床主轴转速超调量小,具有更快的响应时间,跟踪精度高,同时系统能耗减少20%左右;即使受到较大随机干扰,模糊自整定PID控制器也能快速消除干扰,使机床主轴转速处于受控状态。采用模糊自整定PID控制器可以有效提高液压马达驱动机床主轴系统的动态稳定性以及抗干扰能力。

隧道掘进机清渣机械臂运动控制

清渣机械臂采用阀控液压缸系统,具有建模不确定性与强非线性特征。为提高清渣机械臂运动的准确性,提出一种轨迹追踪运动控制方法。基于清渣机械臂缩尺试验台模型,根据改进D-H法建立清渣机械臂运动学模型,基于拉格朗日法建立清渣机械臂非线性耦合动力学模型。针对动力学模型的建模不确定性,使用径向基函数神经网络逼近模型中的未知项,神经网络中的权值使用自适应方法进行在线调节。建立清渣机械臂仿真模型进行验证,结果表明,该方法可以确保清渣机械臂轨迹追踪过程具有较小的误差。

履带式果园喷药机遥控作业系统设计

为解决传统喷药机依靠人工驾驶,易引起工作人员中毒的问题,针对履带式果园喷药机,设计了一种喷药机遥控作业系统。遥控系统采用ECU作为控制核心,采用飞控系统替代传统的遥控系统进行无线远距离通信,采用液压阀组控制液压油缸来驱动操纵杆动作,从而实现对喷药机的启停、转向和喷药等远距离操纵。在履带式果园喷药机上集成该系统,对系统进行了性能测试,结果表明:系统的有效遥控距离不小于200m,在遥控距离不超过200m的条件下,行走控制响应时间不大于0.6s,遥控距离对系统响应时间几乎没有影响。通过人为切断无线信号的方法,进行了模拟掉线试验,结果表明:喷药机在遥控系统掉线后的停车成功率达到100%。系统具有响应快、通信稳定和安全性高的特点,能够满足果园喷药作业要求。