Response characteristics of sonar receiver under intense sound pulse

For anti-jamming and anti-countermeasure techniques of the sonar receiver, the response characteristics of the automatic gain control (AGC) circuit and the survivability of the prime circuit under strong interference are analyzed by simulations and experiments. An AGC simulation model based on the voltage control amplifier VCA810 prototype is proposed. Then static and dynamic simulations are realized with single frequency signal and linear frequency modulated (LFM) signal commonly used in the active sonar. Based on intense sound pulse (ISP) interference experiments, the real-time response characteristics of each module of the receiver are studied to verify the correctness of the model as well as the simulation results. Simulation and experiment results show that, under 252 dB/20 μs ISP interference, the specific sonar receiver will produce sustained cut top oscillation above 30 ms, which may affect the receiver and block the regular sonar signal.     

Vector tracking loops in GNSS receivers for dynamic weak signals

Vehicle positioning with the global navigation satellite system(GNSS) in urban environments faces two problems which are attenuation and dynamic.For traditional GNSS receivers hardly able to track dynamic weak signals,the coupling between all visible satellite signals is ignored in the absence of navigation state feedback,and thermal noise error and dynamic stress threshold are contradictory due to non-coherent discriminators.The vector delay/frequency locked loop(VDFLL) with navigation state feedback and the joint vector tracking loop(JVTL) with coherent discriminator which is a synchronization parameter tracking loop based on maximum likelihood estimation(MLE) are proposed to improve the tracking sensitivity of GNSS receiver in dynamic weak signal environments.A joint vector position tracking loop(JVPTL) directly tracking user position and velocity is proposed to further improve tracking sensitivity.The coherent navigation parameter discriminator of JVPTL,being able to ease the contradiction between thermal noise error and dynamic stress threshold,is based on MLE according to the navigation parameter based linear model of received baseband signals.Simulation results show that JVPTL,which combines the advantages of both VDFLL and JVTL,performs better than both VDFLL and JVTL in dynamic weak signal environments.     

基于“当前”统计模型的高动态GPS信号跟踪算法

提出了一种新的高动态GPS信号跟踪算法,基于＂当前＂统计模型对载波瞬时相位过程、瞬时频率及瞬时频率变化率过程进行建模;在此基础上,结合系统状态方程为线性而量测方程为非线性的特性,采用简化UKF算法对信号参数进行估计,同时采用EKF和标准UKF滤波算法在同等条件下对信号参数进行估计比对。仿真结果表明对信号参数所建模型能真实反映信号的过程,验证了所建模型的正确性的;简化UKF参数估计结果不仅精度与标准UKF相当且具有较高的运算效率,能更好满足高动态下的实时性需求。

Abstract：

A new high dynamic GPS signal tracking algorithm was proposed.Based on current statistical model,a new model for the GPS signal transitional process was established.Since the system involved a linear state equation and a nonlinear measurement equation,a simple Unscented Kalman Filter （UKF） algorithm was applied to estimation the signal parameters.For comparison purpose,an Extended Kalman Filter （EKF） algorithm and a standard UKF algorithm were also applied to the system to illustrate the effectiveness of the proposed filtering algorithm.Simulation results show that the new model can precisely represent the real signal process,and the simple UKF algorithm achieves high precision comparable to standard UKF with higher operation efficiency.Therefore,the new model and the proposed algorithm can satisfy real time requirement in high dynamic environment.     

Zero phase error control based on neural compensation for flight simulator servo system

1. INTRODUCTION In high precision tracking applications of mechanical systems, feedforward controllers are often used to enhance tracking performance, and they are generally prefilter for the desired trajectory to compensate for the dynamic lag of the closed loop and to extend the tracking bandwidth. Because of the rapid growth of computer technology, digital motion control system has become more and more popular, and feedforward controller design in discrete time domain attracts much atte…     

新型压电式气动PWM数字比例阀建模及仿真研究

针对采用电磁铁为电-机械转换器的传统气动PWM比例阀存在着响应时间慢,稳态精度差等缺点,提出了一种以压电叠堆为电-机械转换器的新型压电式气动PWM数字比例阀,建立了其数学模型,并利用Matlab/Simulink建立其仿真模型;通过仿真及试验结果的对比,证明了所建数学模型是准确的。仿真研究了先导阀芯输出位移、PWM载波频率及PID控制等对阀性能的影响,为今后进一步优化结构参数及控制参数的选择提供了依据。

Abstract：

The traditional electro-pneumatic PWM proportional valve driven by electro-mechanical converter of electromagnet has the disadvantages of slow response and poor control precision etc.To solve this problem,a novel piezoelectric type pneumatic PWM digital proportional valve driven by the electro-mechanical converter of piezoelectric stack was proposed.The mathematics model of PWM proportional valve was set up and its simulation model was built by means of Matlab/Simulink.By the comparison of simulation and experiment results,the built mathematical model was proved to be accurate.Moreover,the effect of pilot valve core displacement,PWM carrier frequency and PID control to the PWM valve performance was researched by simulation,which will provide theoretical steering to further optimize the valve structure parameters and the choice of control parameters.     

Output feedback adaptive control of multivariable nonlinear systems using Nussbaum gain method

1. INTRODUCTION Output feedback adaptive control of single input and single output (SISO) nonlinear systems with unknown constant parameters has been well developed via backstepping design[1]. In order to achieve asymptotic tracking of a known reference trajectory, a restrictive assumption is the sign of the high frequency gain to be known. Some results for relaxing this assumption have also been proposed [2]. It has been shown that if the sign of the high frequency gain is unknown, the …     

基于博弈论组网多机动目标协同跟踪技术研究

在卫星多目标跟踪的背景下,针对传感器网络的协同问题,首次建立了完整的基于移动动态联盟的多目标协同跟踪模型,并针对协同过程中的移动动态联盟形成问题,提出了基于博弈论的联盟形成算法。该协同模型在跟踪多目标时利用移动动态联盟来交换并协调节点间的信息,使节点的行为一致,具有分布式和自组织的特点。仿真实验验证了该协同模型应用在传感器网络多目标跟踪中的有效性。

Abstract：

As to the collaborative technique in sensor network,an integrated multi-target collaborative tracking model was constructed based on mobile dynamic coalition under the background of multi-satellite tracking.Then as to the mobile dynamic coalition formation,a coalition formation method was proposed based on game theory.Using mobile dynamic coalition,this collaborative model exchanged and coordinated the information of nodes to accord their action.So it is distributive and self-organizing.Simulation results validate the effectiveness of collaborative model in sensor network tracking multi-target.     

基于前馈及反馈补偿的高性能直线伺服系统

数控机床用直线电动机在工作过程中,推力波动、负载扰动和非线性摩擦等各种扰动因素降低了直线伺服的性能。为抑制扰动满足数控机床直线伺服系统速度跟踪性能的要求,在分析永磁直线同步电动机数学模型和各种扰动因素的基础上,引入具有动态递归特性的Elman神经网络,设计出具有前馈及反馈综合补偿效果的复合控制器,不仅可以对各种扰动进行反馈补偿,而且对速度给定信号进行预测前馈补偿控制,提高了直线伺服系统的跟踪精度和响应速度,仿真结果验证了Elman神经网络的动态性能及综合补偿的优点,表明了复合控制方案的有效性和可行性。

Abstract：

Disturbance variations,such as force ripple,load disturbance and nonlinear friction,directly impose on the motor shaft,leading to significant effect on the computer numerical control （CNC） machine tool servo system performance.In order to satisfy the requirements for speed command tracking performance and eliminate the influence of disturbance,on the bases of the analyzing the mathematics model of permanent magnet linear synchronous motor （PMLSM） and disturbance variation,Elman dynamic recurrent Neural Network was introduced and compound controller with feedforward and feedback comprehensive compensation was proposed.The disturbances were compensated by feedback component and reference speed input signal was preview controlled by feedforward component.The tracking performance and respect speed of linear server system were improved.The advantages of the comprehensive compensation and dynamic of Elman NN were proved.The simulation results show that this compound control scheme is feasible and effective.     

GPS接收机伪码跟踪技术研究及仿真

高动态的接收机指在接收信号的载波附有较高的随时间变化的多普勒频移时仍能正常工作的接收机。GPS接收机主要通过载波叉积自动频率跟踪技术以及载波辅助技术等方法来应对高多普勒频移。本次重点研究了高动态GPS接收机扩频接收核心技术中与载波叉积自动频率跟踪技术相匹配的GOLD码跟踪技术，在此基础上建立了仿真的系统模型，并根据此模型应用Matlab simulink进行了具体的实现。     

一种新型UUV半实物仿真系统设计与实现

针对UUV导航与控制系统高精度仿真的需要,设计了一种支持捷联惯导、多普勒测速仪、深度传感器和GPS接收机接入的半实物仿真系统,解决了GPS卫星导航信号仿真、多普勒测速仪水声回波模拟和UUV深浅水航行深度模拟问题,进行了导航与控制系统的半实物仿真试验,分别测试了GPS导航仿真子系统、多普勒测速仿真子系统和深度模拟子系统。试验结果表明,该仿真系统满足了仿真实时性和计算精度的要求,对于UUV研制具有重要的应用价值。

Abstract：

To satisfy the requirement of high accuracy simulation of complicated navigation and control system of unmanned underwater vehicle, a new plan of simulation system was proposed, which afforded the interface environment for SINS, Doppler velocity instrument, depth sensor and GPS receiver. The GPS satellite navigation signal simulation, the acoustic echo of Doppler velocity instrument and the sailing depth simulation were solved. The simulation experimentation combining hardware was processed, and the GPS simulation subsystem, the Doppler velocity simulation subsystem and the sailing depth simulation subsystem were all tested. The results show that the simulation system meets the real-time and accuracy requirements, and the system has important application value for UUV development.     

载波跟踪算法综述

随着GPS软件接收机技术的飞速发展,作为其关键技术之一的载波跟踪算法也取得了长足进展。基于一种典型载波跟踪环的结构,将载波跟踪算法归类为纯载波跟踪算法和有外部辅助载波跟踪算法两大类。其中纯载波跟踪算法的关键技术主要有:环路鉴别算法,环路滤波器的优化设计,基于锁相环和锁频环的混合载波跟踪环的设计,智能降噪技术、智能控制技术、智能估计算法和自适应算法的引入等;外部辅助的载波跟踪算法主要存在于各类组合导航系统中,最典型的就是紧耦合或超紧致耦合组合导航系统中利用惯导测量信息对载波跟踪进行辅助。分析了上述各种技术研究的侧重点及工作原理,总结了各种研究侧重点的特点及优缺点,指出了载波跟踪算法的发展方向。     

Digital implementation and analysis of a high dynamic frequency tracking loop

In the wireless guidance system,the signals that receiver received has obvious Doppler shift for the high dynamic characteristic of the carrier.A new solution of carrier frequency tracking loop with frequency modifying system is put forward.The characteristic of cross product auto frequency control and the second order loop filter in this loop are analyzed.The simulation shows that this loop can accomplish frequency tracking well in high dynamic circumstance.     

高动态GPS载波跟踪算法研究

为了寻求更好的高动态GPS载波跟踪解决方案,设计了适于高动态环境的基于参数估计的载波跟踪环路,分析了高动态GPS载波跟踪系统模型,比较了EKF、UKF和PF三种滤波算法的参数估计性能。在此基础上,完成了基于EKF、UKF和PF的载波跟踪环路的设计,并以JPL提出的高动态模型为例进行仿真验证。仿真结果表明,虽然这三种算法均能实现对高动态信号的精确跟踪,但总体而言,基于PF的载波跟踪环路具有更好的动态适应能力。另外,鉴于高动态GPS接收机应用场合的特殊性,又对PF滤波算法在非线性、非高斯GPS载波系统的假设下进行了仿真验证,结果显示了应用粒子滤波算法解决非高斯噪声干扰载波跟踪问题的可行性。     

高动态跳频载波跟踪技术

在无人机或导弹等高速运动目标间建立稳定、可靠的通信链路,需要突破高动态下的载波跟踪技术,考虑跳频通信系统的突发传输模式,本文提出基于开环最大似然估计(maximum likelihood estimation,MLE)和扩展卡尔曼滤波跟踪算法的高动态载波信号跟踪技术.通过理论和仿真分析证实了该算法可有效克服传统环路的缺...     

高动态GPS/INS组合导航算法研究

首先介绍了新型深组合GPS/INS系统原理图及组合导航滤波算法。在该算法中,组合卡尔曼滤波器除完成INS误差及GPS接收机时钟误差的估计外,还参与了GPS码跟踪,即完成传统码跟踪环中环路滤波器的功能。采用自适应码跟踪误差估计器补偿组合卡尔曼滤波器测量值中的相关分量,从而消除了传统组合中不稳定的主要根源。然后进行了计算机仿真计算,仿真结果表明,新型深组合GPS/INS导航算法适用于机动性较高的载体。     

动态环境下GPS软件接收机研究

载体的动态性所引入的多普勒频移给GPS接收机的载波跟踪带来了很大的困难。首先介绍了GPS软件接收机捕获与跟踪策略,提出了一种新的基于模糊逻辑控制器和三阶锁相环的动态载波跟踪方案,分析了模糊逻辑控制器的设计原理,推导了适合软件实现的三阶锁相环的数字形式。实验结果证明提出的设计方法与传统环路相比可大幅度缩短载波跟踪时间,减小环路滤波器带宽,并能消除周跳。     

基于MatLab/Simulink的GPS系统仿真

快速可靠的GPS（全球定位系统）系统仿真可对双频GPS接收机的设计、接收算法的研究提供有效的帮助。文中详细介绍了在MatLab／Simulink环境下GPS系统仿真平台构建的基本方法。首先分析了GPS系统的各个环节，说明了各模型在仿真中的实现方法；然后给出了完整的系统仿真框图，并在此平台上实现了GPS L2载波相位跟踪的仿真。结果表明该仿真平台有效、可靠。     

GPS软件基带信号处理与定位实现

在GPS软件接收机架构下,基于计算机MATLAB软件平台,利用实际采集的GPS中频信号,在普通计算机上实现了一个硬件接收机的所有基带信号处理以及导航解算功能：详细介绍了FFT相关捕获方法,经典载波、伪码跟踪环设计;对于接收机中最重要的伪距计算环节,给出一种完全不需要本地时间,而仅利用采样数据,根据由捕获和跟踪得到的观测量,提取出各卫星帧头到达天线的时延差,从而计算伪距的方法,最终实现了定位解算。实验结果表明,利用真实GPS中频数据,可以在GPS软件接收机架构下,完成全部基带信号处理以及定位解算等完整过程,完全实现一个接收机功能,并适合精密单点定位、多模接收机等算法开发。     

改进频率鉴别的载波跟踪环路及性能分析

为了适应高动态环境,导航接收机常采取锁频环和锁相环联合工作实现载波跟踪。对其中较常用的的叉积自动频率跟踪环提出改进,利用两种方法切换实现频率鉴别。改进后算法克服了数据位模糊,并且使鉴频范围扩大了4倍,同时保持跟踪精度不变。影响跟踪精度的因素主要包括热噪声误差和动态应力误差,经研究发现其中热噪声误差的传统理论分析结果与实际有较大差距。利用环路线性化近似处理,并且考虑鉴别噪声间的相关性,经重新推导得到锁频环路的热噪声跟踪误差低于传统理论分析结果的1/5。通过仿真对锁频环鉴频范围和热噪声跟踪误差分析的正确性进行了验证。