High precise control method for a new type of piezoelectric electro-hydraulic servo valve

A new type of piezoelectric electro-hydraulic servo valve system was proposed. And then multilayer piezoelectric actuator based on new piezoelectric ceramic material was used as the electricity-machine converter of the proposed piezoelectric electro-hydraulic servo valve. The proposed piezoelectric electro-hydraulic servo valve has ascendant performance compared with conventional ones. But the system is of high nonlinearity and uncertainty, it cannot achieve favorable control performance by conventional control method. To develop an efficient way to control piezoelectric electro-hydraulic servo valve system, a high-precise fuzzy control method with hysteresis nonlinear model in feedforward loop was proposed. The control method is separated into two parts: a feedforward loop with Preisach hysteresis nonlinear model and a feedback loop with high-precise fuzzy control. Experimental results show that the hysteresis loop and the maximum output hysteresis by the PID control method are 4.22% and 2.11 μm, respectively; the hysteresis loop and the maximum output hysteresis by the proposed control method respectively are 0.74% and 0.37 μm, respectively; the maximum tracking error by the PID control method for sine wave reference signal is about 5.02%, the maximum tracking error by the proposed control method for sine wave reference signal is about 0.85%.     

Adaptive key SURF feature extraction and application in unmanned vehicle dynamic object recognition

A new method based on adaptive Hessian matrix threshold of finding key SRUF( speeded up robust features) features is proposed and is applied to an unmanned vehicle for its dynamic object recognition and guided navigation. First,the object recognition algorithm based on SURF feature matching for unmanned vehicle guided navigation is introduced. Then,the standard local invariant feature extraction algorithm SRUF is analyzed,the Hessian Metrix is especially discussed,and a method of adaptive Hessian threshold is proposed which is based on correct matching point pairs threshold feedback under a close loop frame. At last,different dynamic object recognition experiments under different weather light conditions are discussed. The experimental result shows that the key SURF feature abstract algorithm and the dynamic object recognition method can be used for unmanned vehicle systems.     

Optimization of the carrier tracking loop for GPS high dynamic receivers

A carrier tracking loop which can adjust the loop parameters adaptively is proposed for high dynamic application.Three modules,called theα-β-γfilter model,adaptive loop structure model and adaptive loop bandwidth model respectively,are added in the presented tracking loop compared with the traditional carrier tracking loop based on the second-order frequency lock loop(FLL)assisting third-order phase lock loop(PLL)loop filter.And the optimization methods for the tracking bandwidth and the carrier loop order are analyzed.The real-time estimation methods of the dynamic parameters,the velocity,acceleration and jerk along the line of sight(LOS)between the satellite and the receiver's antenna,and the measurement parameters are discussed based on the presentedα-β-γfilter algorithm.A method is introduced to improve the filter's dynamic response to meet high dynamic application by self-adjustedα-βγfilter coefficient used in the tracking loop.The performance of three cases with different carrier tracking loop is compared by simulation.     

Test research and computer simulation analysis of construction state during form finding for suspen-dome system

A novel construction method without scaffold work called as assembly-prestressing form finding loop by loop is presented.Based on the theory of finite displacement,the cycle-forward analysis method is presented for its construction calculation,which adopts the finite element method of generalized geometric nonlinearity combined with the application in the real construction process.By means of the combination of the forward analysis according to real construction sequence and the cycle iteration according to the initial strain increment method of cable force adjustment,the influence of the structural geometric nonlinearity and the loss of prestress are taken into account due to prestressing of tendons in turn and so on.If the initial cable forces derived from the method were used for construction,expected cable forces and shape could be assured easily.Simulation analysis achieved real-time tracking and controlling of the construction status.Finally,according to the procedure and parameters in simulating,a model experimental research on the stage of form finding(namely prestressing)was carried out for suspen-dome structure.The feasibility on the assembly-prestressing form finding method loop by loop was testified.The cycle-forward analysis method was established and numerical simulation was performed,and the results show that it was useful for the design and the construction of similar suspen-dome structure.     

A Damping Characteristics Calculation Method of Metal Dry Friction Isolators

The dry friction ring-type vibration isolator is considered as an isotropic continuous medium.A method of dry friction hysteresis loop calculation is proposed based on friction force analysis of contact beam.The friction force is modeled as an equivalent distributed moment to use the finite element method(FEM)to calculate the dry friction vibration isolator hysteresis loop,so the damping characteristics can be obtained.A comparison of the hysteresis loop calculation results and the experimental results shows the average relative error is 2.7%,it proves the calculation method is feasible.     

Designing of optimal double loop networks

The double loop network G(N; r, s) has N vertices and 2N directed edges. A natural question is how to choose r and s such that G(N; r, s) has diameter as short as possible for a given N. In 1993, Li, Xu and Zhang proposed a method of constructing double loop networks with the minimum diameter for the case of r=1.The method is developed to construct such networks that none of their minimum diameters can be reached at r=1.As a by-product, a flaw in an assertation by Esqu et al. is pointed out.     

Prediction Technology of Buried Water- Bearing Structures in Coal Mines Using Transient Electromagnetic Method

Buried water-conducting and water-bearing structures in front of the driving head may easily lead to water bursts in coal mines. Therefore,it is very important for the safety of production to make an accurate and timely forecast about water bursts. Based on the smoke ring effect of transient electromagnetic fields,the principle of transient electro-magnetic method used in detecting buried water-bearing structures in coal mines in advance,is discussed. Small multi-turn loop configurations used in coal mines are proposed and a field procedure of semicircular sector scanning is presented. The application of this method in one coal mine indicates that the technology has many advantages compared with others. The method is inexpensive,highly accurate and efficient. Suggestions are presented for future solutions to some remaining problems.     

Trajectory planning and tracking control for underactuated unmanned surface vessels简

The trajectory planning and tracking control for an underactuated unmanned surface vessel（USV） were addressed.The reference trajectory was generated by a virtual USV,and the error equation of trajectory tracking for underactuated USV was obtained,which transformed the tracking and stabilization problem of underactuated USV into the stabilization problem of the trajectory tracking error equation.A nonlinear state feedback controller was proposed based on backstepping technique and Lyapunov＇s direct method.By means of Lyapunov analysis,it is proved that the proposed controller ensures that the solutions of closed loop system have the ultimate boundedness property.Numerical simulation results are presented to validate the effectiveness and robustness of the proposed controller.     

Proportional integral derivative controller design using Legendre orthogonal functions

The Legendre orthogonal functions are employed to design the family of PID controllers for a variety of plants. In the proposed method, the PID controller and the plant model are represented with their corresponding Legendre series. Matching the first three terms of the Legendre series of the loop gain with the desired one gives the PID controller parameters. The closed loop system stability conditions in terms of the Legendre basis function pole(λ) for a wide range of systems including the first order, second order, double integrator, first order plus dead time, and first order unstable plants are obtained. For first order and double integrator plants, the closed loop system stability is preserved for all values of λ and for the other plants, an appropriate range in terms of λ is obtained. The optimum value of λ to attain a minimum integral square error performance index in the presence of the control signal constraints is achieved. The numerical simulations demonstrate the benefits of the Legendre based PID controller.     

A Reconfigurable Manufacturing System for In-site Machining Component with Large Scale

To cope with various unpredictable changes in large scale parts,the concept of reconfigurable manufacturing system (RMS) for machining these components is presented.Considering with large-size space measurement and the fixed-free manufacture mode,an automatically localizing machining method for large scale part is studied in this paper,and the architecture of the RMS for machining large scale parts is proposed.According to the method and structure,the automatically localizing model is established.The theoretical analysis and simulation examples demonstrate the feasibility and validity of the proposed method,and the results indicate that the method is suitable and effective for machining large scale components in significant scientific projects.     

电能计量互感器二次回路状态识别系统

针对目前互感器二次回路窃电方法逐步趋于高科技化和隐蔽化的问题,分析了互感器二次回路在不同故障、窃电情况下的等效模型,提出了一种基于阻抗特性的互感器二次回路状态识别方法.采用谐振检测电路技术,研制了二次回路终端检测装置和互感器二次回路状态巡检仪,通过现场测试验证了该方法的可行性.结果表明,基于该方法研制的装置能够实现互感器二次回路的状态监测.     

一种积分过程PID自整定方法

针对积分加滞后过程,提出了一种设定值加权的PID控制器参数自整定方法,并且针对该方法定义了一种鲁棒性能指标.首先引入一种内部反馈结构, 利用内部反馈结构中的比例控制器将积分过程转换为广义稳定过程,这就使得普通PID控制器设计方法可以在积分过程中得以应用.利用该方法并基于该鲁棒指标设计的控制器一方面克服了传统PID控制方法在控制积分过程时存在的结构上的缺陷,同时又提高了系统的鲁棒性和控制性能,仿真结果也表明基于本方法整定的控制器的控制效果要优于其它方法.     

串级不稳定时滞过程的内模控制器设计

针对串级不稳定时滞过程研究了内模控制器的设计方法。该方法副回路采用传统内模控制,能及时快速消除内环干扰对系统整体控制性能的影响;主回路采用一种二自由度内模控制结构,将设定值跟随特性与干扰抑制特性解耦,控制器的参数整定不需要在两种特性之间折中选择,克服了传统内模控制的不足。理论分析和仿真结果表明,该方法不仅能有效减少控制器的个数,而且可使系统同时获得良好的设定值跟随特性、干扰抑制特性和鲁棒性。     

基于RTDS的变压器差动保护闭环测试方法

提出了一种利用实时数字仿真系统进行变压器差动保护的闭环测试方法.介绍了仿真系统的建模、操作系统的建模、硬件的连接原理及试验检测方法.仿真结果表明,所提出的闭环检测试验方法能正确检测继电保护装置的变压器差动保护功能.     

磁场环路积分的等价解环

为解决光学电流互感器(OCT)抵卸磁场干扰与运行可靠性的矛盾问题,在提炼了磁场积分环路的等价解环条件的基础上,提出了磁场积分环路的正交解环法和零和解环法.证明了3个基本的解环定理:正交解环定理、零和解环定理和均匀磁场矩形环路的解环定理.提出的正交解环法和零和解环法可以将安培环路定律等价地推广到非环路情况,并给出了实例.该研究为解决光学电流互感器在电力系统的实际应用中抵御磁场干扰与运行稳定性的矛盾问题奠定了理论基础.     

扩展卡尔曼滤波估计载波参数的算法研究

提出了一种在接收信号幅度未知的情况下进行载波参数估计的扩展卡尔曼滤波算法,该算法把信号幅度及伪码自相关的乘积作为一个独立变量和载波相位、频率一起组成状态向量进行扩展卡尔曼滤波。理论分析表明该算法本质上是具有可变增益的幅度锁定环和相位锁定环的联合估计,并给出了稳态时环路闭环传输函数和等效噪声带宽的解析表达式。仿真结果表明该算法在高低信噪比下,均具有较高的估计精度和较快的收敛速度。     

神经网络-滑模控制在STATCOM系统中的应用

研究了基于STATCOM无功补偿的交流系统电压波动和闪变调节与控制问题,建立了STATCOM在d-q坐标系的数学模型,提出了基于直接电流控制策略的神经网络-滑模控制方法:采用电压外环滑模控制和电流内环神经网络-滑模控制的双环控制策略,克服了传统PI控制不能自适应调整控制参数的缺点,实现了系统的自适应控制。数值仿真结果验证了本方法的有效性,在电压波动和闪变恶劣条件下STATCOM能够快速响应、控制品质好,交流系统能够稳定工作,控制性能比PID控制好。     

双线性对快速计算中的多项式选取

针对Miller算法的循环次数,分析了循环控制多项式的性质,得出某些类的循环控制多项式的次数的下限.在此基础上,给出适合于双线性对的椭圆曲线的相关参数的选取方法.最后,给出利用不可约分因子来生成适合于双线性对的椭圆曲线时,MiIler算法的循环次数达到理论下限的充分必要条件.     

基于循环优化的矩阵联合对角化算法及在盲源分离中的应用

通过对一组与盲源分离中观测信号有关的目标矩阵进行近似联合对角化,可以有效解决盲源分离问题。提出一个非正交的循环优化的联合对角化算法。待优化的2个函数分别为矩阵对角化处理后的非对角元素的平方和与对角元素的平方和,通过对两者的循环最小化和最大化处理即可获得对角化器。对比仿真实验表明本文算法可以获得更好的盲源分离效果。