基于MATLAB-AMESim的电液伺服系统模糊PID控制

电液伺服系统在现代工业中有广泛应用,针对实际电液伺服系统中非线性环节建模不准确这一问题,根据MATLAB和AMESim的各自特点,利用AMESim完成复杂实际系统建模,利用MATLAB进行控制器设计,对系统建立联合仿真模型。阐述模糊PID控制器的设计过程,通过仿真结果对比分析模糊PID和传统PID的控制性能。结果显示:在变负载电液伺服控制系统中模糊PID控制器在快速性、控制精度等方面具有更好的控制性能,并且提高了系统的鲁棒性和抗干扰能力。     

流量反馈型电液比例阀的模糊PID控制特性

流量反馈型电液比例阀是一种较为复杂的高阶非线性系统,传统PID对其控制效果不佳。为提高该阀的控制性能,提出一套基于模糊控制理论的参数自整定PID算法。分析电液比例阀工作原理,设计一种两输入三输出的模糊自整定PID控制器;采用Simulink和SimulationX软件,分别建立模糊PID模型和电液比例阀模型,对电液比例阀的控制特性进行仿真分析。结果表明：采用所设计的模糊PID控制器,可有效改善新型电液比例流量方向阀稳定性和动态性能。     

具有压差反馈的电液伺服阀死区补偿策略及控制特性仿真

针对无阀芯位移电液伺服阀死区引起的流量非线性问题,在分析电液伺服阀死区模型的基础上,设计得到了一种具有压差反馈的电液伺服阀死区补偿模型,实现了无需通过位移反馈便能达到对死区的补偿作用.模拟补偿电压信号增加到电液伺服阀的控制系统中,并通过设置比例流量阀在不同变化阶段的"电压-流量"斜率来达到快速补偿比例流量阀流量的作用....     

泵控电液伺服系统多模态可拓控制研究

针对泵控电液伺服系统位置控制的快速性、稳定性和精确性存在矛盾的问题,本文提出了一种多模态可拓控制电液伺服系统,将可拓方法应用于系统设计中.多模态可拓控制切换器根据提取的系统特征信息,建立特征状态的关联函数,根据关联度划分测度模式将系统运动分为三段,分别由Bang-Bang控制器、模糊控制器和PID控制器进行分段控制.仿...     

电液同步控制策略研究

本文着重分析了电液同步控制结构对同步控制特性的影响 ,并提出了克服电液比例位置控制死区非线性的变死区自学习补偿算法 ,实现了高精度的同步控制。     

电液比例高精度定位的变死区自学习补偿研究

针对电液比例方向阀特有的变流量死区特性，本文提出了一种基于数字控制变死区自学习补偿方法，试验表明，该方法较大地提高了电液比例定位系统的定位精度、抗干扰能力和稳定性，并有良好的实时性。拓宽了电液比例定位系统在高精度定位领域的应用范围。     

电液同步控制策略研究

本文着重分析了电液同步控制结构对同步控制特性的影响,并提出了克服电液比例位置控制死区非线性的变死区自学习补偿算法,实现了高精度的同步控制。     

基于FPGA的电液比例位置系统模糊控制器设计

电液比例位置系统是一种典型的非线性时变系统,其参数具有非线性特性,常用的线性化模型基础上的经典控制器,难以取得满意的控制效果.笔者将模糊控制器应用于电液比例位置系统,并采用FPGA芯片,通过VHDL语言设计实现了一个二输入一输出模糊控制器.实验结果表明,控制器推理结果正确,能够稳定、可靠地工作.     

基于模糊PID控制的电液比例阀控缸系统泄漏补偿研究

为解决电液比例阀控缸系统存在的系统死区非线性因素、液压缸泄漏的问题，搭建了基于AMESim和Simulink联合仿真的电液比例阀控缸系统模型，对是否考虑泄漏的阀控缸系统影响其动态特性的主要因素进行联合仿真分析；针对阀控缸系统存在的问题设计了模糊PID控制器，得到液压缸活塞位移与泄漏量之间的关系以及对系统性能的影响规律，与传统PID控制器进行仿真实验对比。结果表明：模糊PID控制器在解决系统非线性影响因素、液压缸泄漏等问题中具有良好的效果，控制响应速度更理想，且系统无超调、无振荡、鲁棒性强。     

基于遗传算法优化的模糊PID在粉末液压机伺服系统的应用研究

CNC粉末冶金液压机电液伺服系统具有时变性、易受干扰等特点,运用常规的PID控制难以达到满意的控制效果.运用模糊PID控制实现对PID参数的在线自适应整定,提高了PID控制器对电液伺服系统的调节控制能力.为了进一步提高模糊PID控制器的控制性能,采用遗传算法对模糊PID控制器的初始PID参数和比例因子进行了优化.仿真结果表明:基于遗传算法优化的模糊PID控制器在CNC粉末冶金液压机电液伺服系统的控制中具有良好的自适应性、鲁棒性和稳定性.     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.