基于AMESim的直驱式电液伺服舵机控制系统的建模与仿真

舵机控制系统性能的优劣直接影响飞行器的飞行姿态与轨迹控制精度。介绍了一种直驱式电液伺服舵机控制系统的工作原理和结构组成特点,并基于AMESim平台对其进行了建模和仿真分析。为了满足控制系统动态响应及位置误差的要求,提出单一神经元自适应PID控制方法。仿真结果表明:该直驱式电液伺服舵机正反向运动性能稳定、响应速度快,稳态误差较小,能够满足飞行器舵机性能指标要求。     

基于GD-FNN的四旋翼无人机姿态控制系统设计

针对6自由度非线性欠驱动的四旋翼无人机飞行姿态易受外部干扰、超调较大、响应较慢等问题,文章基于广义动态模糊神经网络(GD-FNN)设计了一种四旋翼无人机姿态控制系统,并基于Lyapunov函数对系统的稳定性做出了证明。该控制系统结合了GD-FNN的优点,使得系统可同步调整学习时的参数和结构且学习速度快,在高复杂性、不确定性以及存在外部扰动的情况下具备较强的鲁棒性和自适应性。实验结果表明,基于GD-FNN自适应控制系统较传统的PID控制器具有更优越的控制性能,当系统受到外部噪声干扰时,能够快速实现四旋翼无人机高精度和超调小的飞行姿态自适应控制。     

四轴飞行器的视觉定位设计与实现

四轴飞行器搬运物体时,位置定位起到了关键性作用。为了实现四轴飞行器的自主定位飞行,设计了一款基于视觉定位的四轴飞行控制系统。该四轴飞行器选用K60作为控制器,采用陀螺仪、加速度计和电子罗盘构建航姿测量模块,利用摄像头定位和超声波测距构建定位模块,提高导航精度。飞行器将采集到的数据结合互补滤波进行姿态解算,经过经典PID控制,实现稳定飞行、视觉定位并自主降落的功能。测试实验结果表明:在10～200 cm的降落高度范围内,飞行器的定位精度达到1.3 mm,高度精度达到0.34 mm,同时整个系统具有较好的快速性和稳定性。因此该四轴飞行器能够实现自主定位飞行,并为无人机定位方式的研究提供了一定的参考。     

基于模糊PID混合的四旋翼飞行器全控制系统设计

对四轴飞行器的结构分析建立动力学模型,并针对其飞行过程中存在的问题,采用模糊PID与传统PID混合的串级控制方法进行研究.由于四轴飞行器是在空间上具有6个活动自由度而仅有4个控制自由度的欠驱动系统,因此该系统通过直接控制飞行器的空间坐标系上的线位移x, y, z和偏航角Ψ,从而间接控制滚转角φ和俯仰角θ,实现飞行器的全控制.使用模糊自适应PID与传统PID混合控制使得飞行器在加入扰动后具有更强的鲁棒性,从而提升了机体的抗干扰能力.     

基于模糊PID混合的四旋翼飞行器全控制系统设计（英文）

对四轴飞行器的结构分析建立动力学模型,并针对其飞行过程中存在的问题,采用模糊PID与传统PID混合的串级控制方法进行研究。由于四轴飞行器是在空间上具有6个活动自由度而仅有4个控制自由度的欠驱动系统,因此该系统通过直接控制飞行器的空间坐标系上的线位移x,y,z和偏航角ψ,从而间接控制滚转角φ和俯仰角θ,实现飞行器的全控制。使用模糊自适应PID与传统PID混合控制使得飞行器在加入扰动后具有更强的鲁棒性,从而提升了机体的抗干扰能力。     

MFA在精密注塑过程电液控制系统中的应用

针对精密注塑机电液控制系统在注塑成型过程中,其过程模型难于确定的特点,为避免系统因过程模型问题而造成注塑精度下降的状况,提出采用无模型自适应控制方案解决相关问题.建立单输入单输出MFA(Model Free Adaptive,无模型自适应控制)控制器,对注塑控制过程过程进行仿真.结果表明,该方法能够较好地解决精密注塑过程的控制问题,具有较高的控制精度.     

基于死区时间补偿的永磁同步电机改进型模糊自适应PI控制策略

由于模糊自适应PI控制不需要精确的被控对象数学模型,且对于线性系统和非线性系统都具有良好的适用能力,而逐渐应用到电机控制系统中来。但传统模糊自适应PI控制在应用过程中,存在控制性能较差的问题。在模糊自适应PI控制理论基础上,提出一种基于死区时间补偿的永磁同步电机改进型模糊自适应PI控制策略,采用该策略能够实现无论在加速阶段还是减速阶段,均能准确、稳定地调节永磁同步电机转速。     

基于模糊自适应PID控制的六旋翼飞行器稳定性控制（英文）

介绍了六旋翼飞行器的运动方式,根据牛顿-欧拉方程完成动力学模型的建立。依据模糊控制的相关理论以及模糊自整定PID控制器的设计过程,完成了基于模糊自适应PID算法的控制器的设计。通过对自适应模糊PID控制器进行Matlab/Simulink下的系统仿真分析,得出所设计的控制器能够较好的完成悬停任务,实现对飞行器的稳定性控制。通过试验验证了六旋翼飞行器的控制稳定性。     

基于模糊自适应PID控制的六旋翼飞行器稳定性控制

介绍了六旋翼飞行器的运动方式,根据牛顿-欧拉方程完成动力学模型的建立.依据模糊控制的相关理论以及模糊自整定PID控制器的设计过程,完成了基于模糊自适应PID算法的控制器的设计.通过对自适应模糊PID控制器进行Matlab/Simulink下的系统仿真分析,得出所设计的控制器能够较好的完成悬停任务,实现对飞行器的稳定性控制.通过试验验证了六旋翼飞行器的控制稳定性.     

基于PID控制的内焊机自动转弯系统设计

为了解决目前内焊机在山地等复杂场景下的自动化应用需求,文中采用了多传感融合的技术方案,通过获取内焊机三维空间中的姿态及驱动轮的电流参数,对内焊机机身进行姿态数据解算,进而完成机身姿态矫正和驱动轮差速控制。闭环控制算法采用了PID经典控制理论方法,在姿态及驱动电流数据采集和控制方案上,系统分别采用了位置式和增量式PID控制方案,从而防止采集数据的误差造成系统扰动。文中针对采集数据采用了中值滤波算法进行预处理,同时对控制系统输出控制量进行阈值限幅,从而保证系统能够平稳过渡运行。最后,将上述控制系统部署在A-806/40E内焊机上进行实际试验测试,并对试验数据进行了详细分析统计,取得了良好的试验结果,为实现内焊机智能化打下了技术基础。     

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).     

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.     

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.     

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.