电液集成元件在磨床上的应用

该文介绍了电液集成元件在磨床上应用实例，并简析了改造后电液集成控制系统的特点。     

一种新型复合电液比例阀

目前,电液比例阀在注塑机以及其它领域得到广泛应用。我厂根据本地区情况,研制并开发了复合型电液比例阀。此阀在液压系统中起到了流量、压力双控制作用,可作为一种电液控制元件,用于各种液压控制系统。它除具有双重控制作用外,还具有节省能量、限压以及温度补偿等功能,起到一阀多用的效果。在液压控制系统中可取代多个溢流阀和流量控制阀。工作原理及结构从简化原理图可看出,阀内部基本上是由两部分来分别控制流量和压力。流量控制部分由大位移比例电磁铁控制的直动型节流阀和一个三通压力补偿阀。压力补偿阀用以检测节流阀进出口压差,实现流量的恒定。另一部分是一个较小功率的比例电磁铁,控制一个先导压力阀并带动主阀进行压力控制。此主阀与前面提到的三通压力补偿阀是一体的,因此压力阀控制了流量阀的出口压力,而流量阀因为有了压力阀的补偿作用,其输出     

电液集成元件及在珩磨机上的应用

北京某厂从国外进口几台4VS6RM四轴珩磨机,该珩磨机的进给机构采用液压系统,进给方式采用压力控制,如图1所示.其原理是用一个进给油缸通过顶杆使珩磨条扩张,由减压阀预先调好进给压力,因此,其生产率和加工精度不能兼顾.若采用两个或两个以上减压阀并联来实现不同的控制压力,在珩磨过程中也只能得到几种压力和珩磨速度,且成本高,两种压力切换时引起的压力超调量大.本文采用电液集成元件组成一简单的液路代替单向减压阀,则很容易实现无级调速和调压.     

电液元件数字化技术进展

本文简要介绍了电液数字阀的种类及结构特点。通过分析说明了电液元件数字化技术的优势，指出了电液元件向数字化方向发展是其必然趋势。     

电液伺服技术的最新成果：压电元件驱动的超高速电液伺服阀

工程应用中常需用超高速电液伺服阀。目前的高速电液伺服阀频宽一般为400Hz左右,远远不能满足需要。如何进一步提高电液伺服阀的频宽是液压技术发展中的一个难题。介绍了日本东京工业大学研制的用压电元件驱动的超高速电液伺服阀,该电液伺服阀频宽高达5kHz,使电液伺服技术的频宽跃上了一个新的台阶,国际液压界为之瞩目。     

现代电液控制技术的应用与发展

本文在对国内外电液元件、电液控制系统、现代控制技术相关文献调研的基础上,指出了电液控制技术已经向数字化转变,其发展过程是与控制策略的最新发展密切相关的。各种新颖控制手段的不断发展和完善,为电液控制技术在各领域的不断推广使用奠定了基础。     

一种新型电液伺服阀

本文介绍了一种新型耐污染性能较好的电液伺服阀的原理和特性。     

一种新型电液执行器设计

针对当前电液伺服执行器存在的不足,设计了一种集性能优越、节能、操作及应用方式灵活等特点于一体的新型执行器,其性能和基本参数均达到了设计要求.文中阐述了该执行器的组成、液压系统及控制原理.     

一种新型电液伺服阀

一种新型电液伺服阀叶劲松武汉钢铁（集团）公司炼铁厂，４３００８３湖北武汉武钢炼铁厂五号高炉的高压阀组（保持高炉内煤气压力恒定的一种调节装置）采用了一种新型的环喷式电液伺服阀，该高炉自从１９９１年１０月投产以来，工作良好，因此１９９６年在我厂四号高...     

步进式加热炉电液比例泵缸系统仿真与应用

非对称泵缸系统多用于变速场合，这种泵缸系统多为本质非线性、时变、强干扰系统。本文用PID控制实现电液斜盘位置和流量的控制，使系统的不确定性和非线性等得到补偿。仿真和实验表明，所开发的PID控制器能够较好地实现模型跟踪控制，跟踪性能有较大改善。     

电液系统中新型反步自适应控制器设计

针对非匹配不确定非线性系统的控制问题,介绍了反步控制的基本设计原理,然后提出了一种自适应反步控制算法,该控制方法不需要掌握被控系统不确定因素函数及其导数的上界,基于Lyapunov函数,给出了自适应控制规律,以及CMAC权值调整信息。采用CMAC神经网络在线学习系统的不确定性以及各阶虚拟控制量的导数信息,避免了系统阶次较高时引起的计算膨胀问题;在递推设计的最后一步加入非连续性鲁棒控制作用,克服了CMAC神经网络在线学习系统不确定性带来的误差;另外,该控制算法在实际控制输入前加入了低通滤波器,避免了因输入不连续而可能导致的抖振问题;最后,将所提出的控制算法应用于电液力伺服系统。稳定性分析表明,该控制方法具有渐近稳定性;仿真研究结果表明,该控制算法在理论上是有效的,同时对未知干扰和系统不确定性具有鲁棒特性。     

电液阀在定量发油系统中的应用

论文在分析发油自动化系统典型设计方案的基础上,针对现有发油系统存在的主要问题,作者提出了一种基于CAN总线的微机控制定量发油系统。说明了上,下位机在发油过程中的作用并详细介绍了电液阀的工作过程,通过油库实际运行,从而提高了发油量的准确度．     

起重机电比例泵控液压系统性能研究

阐述了一种大吨位汽车起重机电比例泵控液压系统,介绍了其液压原理,并从节能、高效、可靠、微动性好、动作平稳、复合动作质量高等作业性能方面进行了分析,现已批量投入生产。     

Characterization and quenching of friction-induced limit cycles of electro-hydraulic servovalve control systems with transport delay

This paper develops a systematic and straightforward methodology to characterize and quench the friction-induced limit cycle conditions in electro-hydraulic servovalve control systems with transport delay in the transmission line. The nonlinear friction characteristic is linearized by using its corresponding describing function. The delay time in the transmission line, which could accelerate the generation of limit cycles is particularly considered. The stability equation method together with parameter plane method provides a useful tool for the establishment of necessary conditions to sustain a limit cycle directly in the constructed controller coefficient plane. Also, the stable region, the unstable region, and the limit cycle region are identified in the parameter plane. The parameter plane characterizes a clear relationship between limit cycle amplitude, frequency, transport delay, and the controller coefficients to be designed. The stability of the predicted limit cycle is checked by plotting stability curves. The stability of the system is examined when the viscous gain changes with respect to the temperature of the working fluid. A feasible stable region is characterized in the parameter plane to allow a flexible choice of controller gains. The robust prevention of limit cycle is achieved by selecting controller gains from the asymptotic stability region. The predicted results are verified by simulations. It is seen that the friction-induced limit cycles can be effectively predicted, removed, and quenched via the design of the compensator even in the case of viscous gain and delay time variations unconditionally.     

Parametric adaptive estimation and backstepping control of electro-hydraulic actuator with decayed memory filter

Some unknown parameter estimation of electro-hydraulic system (EHS) should be considered in hydraulic controller design due to many parameter uncertainties in practice. In this study, a parametric adaptive backstepping control method is proposed to improve the dynamic behavior of EHS under parametric uncertainties and unknown disturbance (i.e., hydraulic parameters and external load). The unknown parameters of EHS model are estimated by the parametric adaptive estimation law. Then the recursive backstepping controller is designed by Lyapunov technique to realize the displacement control of EHS. To avoid explosion of virtual control in traditional backstepping, a decayed memory filter is presented to re-estimate the virtual control and the dynamic external load. The effectiveness of the proposed controller has been demonstrated by comparison with the controller without adaptive and filter estimation. The comparative experimental results in critical working conditions indicate the proposed approach can achieve better dynamic performance on the motion control of Two-DOF robotic arm.     

新型机电液一体化执行机构在催化裂化装置中的应用

本文介绍了新型机电液一体化执行机构的技术背景、主要结构、技术创新、系统原理及示例,说明了新型机电液一体化执行机构具有输出力矩大、控制精度高、机构紧凑、传动平稳、响应速度快、快速切断ESD信号及使用可靠等特点。     

Modeling,simulation and experimental validation of flow rate of electro-hydraulic hitch control valve of agricultural tractor

Advances in non-linear control theory have made it possible to develop controllers for non-linear dynamic systems in their nature. The low-cost proportional control valves of the hydraulic control system are examples of such a system where there is no linearity due to the structure of the valves and the flaws in the spool. However, the non-linear analysis and regulation of these hydraulic systems cannot be done without a proper valve model. This paper presents a methodology for the development of an efficient unified model of a three-point hitch (TPH) electro-hydraulic proportional control valve control system for agricultural tractors by means of a parameter estimation technique. Modeling and simulation of the proportional control valve was performed using MATLAB Simulink software. Parameter estimation methodology was used to optimize the effective orifice opening of the solenoid valve to meet the flow characteristics available in the manufacturer's technical data sheet for the proportional control valve model parameters. Such unified Simulink models are useful for simulation, practical capability testing, and non-linear control design. Modeling and simulation of electro-hydraulic hitch (EHH) control valve were made and simulation results were compared with actual experimental results. The simulation results of the TPH lifting and lowering time were found to vary 4 and 12.5 %, respectively with the experimental results. This type of parameterized valve models facilitates their implementation in dynamic simulation models of complex hydraulic systems.     

Real-time tracking control of electro-hydraulic force servo systems using offline feedback control and adaptive control

This paper focuses on an application of an electro-hydraulic force tracking controller combined with an offline designed feedback controller (ODFC) and an online adaptive compensator in order to improve force tracking performance of an electro-hydraulic force servo system (EHFS). A proportional-integral controller has been employed and a parameter-based force closed-loop transfer function of the EHFS is identified by a continuous system identification algorithm. By taking the identified system model as a nominal plant model, an H_∞ offline design method is employed to establish an optimized feedback controller with consideration of the performance, control efforts, and robustness of the EHFS. In order to overcome the disadvantage of the offline designed controller and cope with the varying dynamics of the EHFS, an online adaptive compensator with a normalized least-mean-square algorithm is cascaded to the force closed-loop system of the EHFS compensated by the ODFC. Some comparative experiments are carried out on a real-time EHFS using an xPC rapid prototype technology, and the proposed controller yields a better force tracking performance improvement.