Nakagami衰落下无人机数据链抗干扰性能

针对信道衰落及 人为干扰共存的电波传播环境,给出了Nakagami衰落下无人机（Unmanned aerial vehicles , UAV)数据链系统的接收信号理论模型。针对单音及连续噪音干扰样式,推导出了接收端 瞬时干信比、瞬时信噪比和瞬时信干噪比的概率密度函数表达式,并据此推导获得了无人机 数据链系统的中断概率和平均错误概率性能表达式。数值仿真结果表明,本文理论分析结果 与仿真值非常吻合,当干扰功率大于噪声功率时,连续噪音的干扰效果优于单音信号3~ 5 dB,本文研究可为无人机数据链干扰及抗干扰技术的研究提供理论基础。     

基于高阶累积量的欺骗式干扰识别方法

为了识别出具体的欺骗干扰方式,从而使雷达可以正确跟踪目标,并有针对性的选择抗干扰方法,本文提出了基于高阶累积量和模式识别技术的欺骗式干扰识别方法.该方法首先给出了欺骗式干扰的3阶和4阶累积量对角切片,在分析其统计特性的基础上,定义欺骗式干扰的高阶累积量特征因子,然后设计基于核聚类的支持向量机分类器,对特征因子进行分类,买现不同欺骗干扰的识别.仿真结果表明,所提出的方法对三种不同欺骗干扰方式的正确识别率高,而且基本不受干噪比影响.     

基于拟合优度检验的灵巧噪声干扰识别

针对传统抗干扰方法无法有效对抗灵巧噪声干扰的缺陷,提出了一种基于拟合优度检验实现灵巧噪声干扰识别的方法.分别根据Swerling起伏模型得到的目标信号分布特性、从灵巧噪声干扰产生过程得到的干扰信号分布特性,分析了目标位置信号与干扰位置信号分布特性差异,提出利用拟合优度检验理论实现干扰识别.该方法计算AD检验统计量,在一定显著性水平下对若干周期同一时刻的样本进行假设检验,根据检验的结果进行干扰识别.仿真实验表明,该方法能有效地对低信干比情况下的目标进行识别.     

干扰场景中基于预测信干比的中继选择方法

针对多用户协作通信网中存在共信道干扰和过时信道状态信息的问题,提出一种通过预测信干比进行中继选择的方法。根据特定的分布产生随机数,将该随机数与测量信干比相加生成预测信干比,选择具有最大预测信干比的中继节点转发数据。在此基础上,对基于该中继选择方法的译码转发协作通信系统进行性能分析,推导获得预测信干比的概率密度函数,从而得到平均误码率和中断概率的解析表达式。仿真结果与理论分析一致,同时数值结果表明,与基于过时信干比的中继选择方法相比,该方法在系统的误码率和中断性能上具有明显优势。     

雷达对无人机系统上行链路的干扰仿真研究

基于对雷达干扰无人机测控系统的情况的分析,提出了基于Simulink的干扰仿真分析系统的建立方法.主要分析了雷达干扰无人机测控系统上行链路的过程,给出了雷达系统、无人机测控系统上行链路模型,并提出了信噪比、干噪比计算的仿真方法.通过全过程仿真和相关实地测试,确保了仿真系统的准确性.仿真结果说明该仿真系统适合模拟雷达干扰无人机测控系统全过程,结果真实、可信.为电磁频谱管理机构进行系统间干扰分析提供了直观、准确的仿真手段,为作战指挥员合理运用战术提供了理论依据.     

一种用于DQPSK卫星通信系统中窄带干扰检测的新方法

以频分多路(FDMA)差分四相移键控(DQPSK)调制方式的数字卫星通信中抗窄带干扰项目为背景，在建立干扰的数学模型基础上，提出了一种变换域方法——快速傅立叶(FFT)变换方法进行干扰检测。这种方法不是采用一个统一的门限值，而是用类似于信号功率谱形状的门限来检测信道中干扰的载波频率、功率、带宽，并根据这些检测值更加精确地设计陷波器的参数。仿真表明当输入信号的信干比为-42dB时，用类似于信号功率谱形状的门限设计的陷波器输出端的信干比为-18dB，而用传统门限设计的陷波器输出端的信干比为-24dB。新方法比传统方法输出信干比提高了6dB。     

基于FPGA的延时块LMS均衡器的设计与实现

码间干扰是影响无人机数据链高速传输的重要因素之一;为了减小码间干扰对数据链的影响,提高数据链的通信速度,文章在LMS算法的基础上,分析并设计具有并行处理功能的延时块LMS均衡器,利用verilog HDL完成了该算法在FPGA上的实现;仿真结果表明均衡器能有效地减少数据链中的码间干扰,通信速度提高一倍,这为以后研究设计更高速均衡器打下了基础。     

16号数据链干扰战术应用研究

16号数据链足外军主要的战术数据链,对其实施大功率干扰能够取得较好的干扰效果,为了达到高效的干扰,战术使用尤为关键,从不同战术应用的角度分析了受到干扰的接收机输入端干信比和输出端误码率,最后通过matlab软件对在不同战术应用方式下的拦阻式干扰的干扰效果进行了仿真分析.仿真结果表明,在不同的战术应用方式中,海-海通信、空中干扰的方式干扰效果最好;而空-海通信、海-海干扰方式情况恰好相反,干扰效果最差;海-海通信、海-海干扰的方式,干扰效果略差于空-空(空-海)通信、空中干扰方式.仿真结果还发现,天线增益的变化对仿真结果影响尤为明显,所以,采用高增益定向天线,能达到更为有效的干扰效果.     

基于霍夫曼树和逆云模型的雷达拖引干扰识别

针对噪声环境中雷达干扰正确识别率较低的问题,提出了一种新的基于霍夫曼树和逆云模型联合的雷达欺骗干扰识别方法.该方法首先利用干扰数据库,提取有效的识别特征参数库,然后基于霍夫曼树建立识别模型.在每个节点,利用基于逆云模型的隶属度分类,实现待测干扰的识别.仿真结果表明,与传统的干扰识别方法相比,该识别方法能很好地应对雷达干扰的随机性和模糊性,能在干扰参数数值区间有重叠时有效识别雷达干扰.     

基于STFT的无人机跳频信号检测与参数估计

为了有效实现对无人机的监管,避免涉密、干扰航班、扰民等事件发生,需快速识别出监测范围内的无人机信号,为此提出一种基于STFT的无人机跳频信号检测与参数估计方法。该技术对接收的信号样本做STFT变换,在时频图上采用时频能量对消法实现无人机跳频信号的盲检测,并在此基础上设计一种自适应的形态学滤波器消除干扰,同时引入最小二乘估计算法提升无人机跳频信号参数估计的性能。通过实验测试表明,算法在SNR不低于6 dB时,无人机跳频信号的检测概率在95%以上,且能正确估计出无人机跳频信号的跳频周期、跳频起跳时刻和跳频频率集等参数,实用性较强,工程使用价值较高。     

伸缩腿双足机器人半被动行走控制研究

研究半被动伸缩腿双足机器人行走控制和周期解的全局稳定性问题.使用杆长可变的倒立摆机器人模型,以支撑腿的伸缩作为行走动力源,采用庞加莱映射方法分析了双足机器人行走的不动点及其稳定性.当脚与地面冲击时,假设两腿间的夹角保持为常数,设计了腿伸缩长度的支撑腿角度反馈控制率.证明了伸缩腿双足机器人行走过程不动点的全局稳定性.仿真结果表明,本文提出的腿伸缩长度反馈控制可以实现伸缩腿双足机器人在水平面上的稳定行走,并且周期步态对执行器干扰和支撑腿初始角速度干扰具有鲁棒性.     

Ascending and descending stairs for a biped robot

This paper synthesizes an efficient walking pattern for a practical biped robot when ascending and descending stairs. The main features of the biped robot include variable length legs and a translatable balance weight in the body. The biped robot's walk is a mixture of both statically stable and dynamically stable modes and relies on some degrees of static stability provided by large feet and by carefully controlling the center of gravity's position. The paper describes the design and experiment of a 7-DOF practical biped which is capable of ascending and descending stairs, and the synthesis of an efficient walking gait for ascending and descending stairs. Our biped robot is one of the few biped walking machines capable of ascending and descending stairs     

Adaptive Gait Control of a Biped Robot Based on Realtime Sensing of the Ground Profile

In this paper, realtime control of dynamic biped locomotion usingsensor information is investigated. We used an ultrasonic rangesensor mounted on the robot to measure the distance from the robot tothe ground surface. During the walking control, the sensor data isconverted into a simple representation of the ground profile inrealtime. We also developed a control architecture based on theLinear Inverted Pendulum Mode which we proposed previously fordynamic walking control. Combining the sensory system and thecontrol system enabled our biped robot, Meltran II, to walk overground of unknown profile successfully.     

Efficiency analysis of telescopic-legged bipedal robots

This paper investigates the stability of underactuated bipedal walking incorporating telescopic-leg actuation. In human walking, knee joints of swing and support legs are bent and stretched. The telescopic legs mimic the motion of the center of mass of human legs via their telescopic motion during the stance phase. First, underactuated telescopic-legged biped robot models are introduced. Second, an output-following control law is applied to the linearized equation of motion of the robot, and the controlled robot’s equation is then specified as a linear time-varying system. The error transition equation is developed to evaluate the stability during the stance phase. Numerical calculations are performed to show the influences of leg telescopic motion on the stability.     

Robust Sliding-mode Control of Nine-link Biped Robot Walking

A nine-link planar biped robot model is considered which, in addition tothe main links (i.e., legs, thighs and trunk), includes a two-segment foot.First, a continuous walking pattern of the biped on a flat terrain issynthesized, and the corresponding desired trajectories of the robot jointsare calculated. Next, the kinematic and dynamic equations that describe itslocomotion during the various walking phases are briefly presented. Finally,a nonlinear robust control approach is followed, motivated by the fact thatthe control which has to guarantee the stability of the biped robot musttake into account its exact nonlinear dynamics. However, an accurate modelof the biped robot is not available in practice, due to the existence ofuncertainties of various kinds such as unmodeled dynamics and parameterinaccuracies. Therefore, under the assumption that the estimation error onthe unknown (probably time-varying) parameters is bounded by a givenfunction, a sliding-mode controller is applied, which provides a successfulway to preserve stability and achieve good performance, despite the presenceof strong modeling imprecisions or uncertainties. The paper includes a setof representative simulation results that demonstrate the very good behaviorof the sliding-mode robust biped controller.     

基于简化三维线性倒立摆模型的模糊控制射门算法

针对双足机器人传统射门算法存在仅适用于固定射门角度和射门姿态的问题,提出了一种基于简化三维线性倒立摆模型的模糊控制射门算法,用于实现多角度、多姿态的射门。首先利用简化三维线性倒立摆模型规划出零力矩点(ZMP)轨迹和质心轨迹;其次在双腿支撑相对双足机器人进行射门角度和姿态的调整,同时利用贝塞尔曲线规划出游动腿的轨迹;最后利用模糊控制算法精确地规划出双足机器人的射门轨迹。实验部分利用NAO机器人仿真平台验证了本文提出射门算法的性能,并与其它射门算法进行了比较。最后将实物NAO机器人用于全过程与多角度的实际射门实验,验证了本文提出射门的算法可行性与准确性。     

Development and motion control of a biped walking robot based on passive walking theory

This research aims to develop the biped walking robot that can walk on the horizontal ground and improve walking efficiency by utilizing the theory of the passive walking robot, namely the pendulum principle. For that, two motors were installed on the hip of the robot to generate the control torques to perform a walking motion. The computer simulations with dynamic model were carried out to investigate the walking capability of the system. Experimental robot was developed considering the calculated results. The proportional control law was used in walking experiment. The robot can walk on the horizontal ground with the proposed method.     

Experimental realization of dynamic walking for a human-riding biped robot,HUBO FX-1

This paper describes a control strategy of the stable walking for the human-riding biped robot, HUBO FX-1. HUBO FX-1 largely consists of two legs with 12 d.o.f., a pelvis and a cockpit. A normal adult can easily ride on HUBO FX-1 by means of a foothold, and can change the walking direction and speed continuously through the use of a joystick. Principally, this kind of robot must be able to carry a payload of at least 100 kg in order to carry a person easily. A sufficient payload can be accomplished by two ways. The first is through the choice of a highly efficient actuator. The second is through weight reduction of the robot body frames. As an efficient actuator, a high-power AC servo motor and a backlash-free harmonic drive reduction gear were utilized. Furthermore, the thickness and the size of the aluminum body frames were sufficiently reduced so that the weight of HUBO FX-1 is light enough. The disadvantage of the weight reduction is that HUBO FX-1 was not able to walk stably due to structural vibrations, as the body structures become more flexible due to this procedure. This problem was solved through the use of a simple theoretical model and a vibration reduction controller based on sensory feedback. In order to endow the robot with a stable biped walking capability, a standard walking pattern and online controllers based on the real-time sensory feedback were designed. Finally, the performance of the real-time balance control strategy was experimentally verified and stable dynamic walking of the human-riding biped robot, HUBO FX-1, carrying one passenger was realized.     

基于模糊控制的双足步行机器人控制研究

本文研制了一台能够独立自主行走的新型的双足步行机器人。机器人的主体部分采用6台伺服舵机,由伺服舵机对机器人进行驱动,同时舵机本身又可作为躯干,使整个机器人的结构非常紧凑。这也是对现有大多数此类机器人进行研究之后所做的改进。对机器人的行走控制由PIC单片机及其相关电路组成。鉴于双足步行机器人是一个复杂系统,故采用模糊控制来提高其控制的精度。经过实际检验,使用模糊控制可以获得很好的控制效果。     

一种小样本支持向量机控制器在两足机器人步态控制的研究

神经网络等传统的机器学习方法是基于样本数目无穷大的经验风险最小化原则,这对非确定环境下有限样本的步态学习控制非常不利．针对两足机器人面临的非确定环境适应性难题,提出了一种基于支持向量机（SVM）的两足机器人步态控制方法,解决了小样本条件下的步态学习控制问题．提出了一种基于混合核的步态回归方法,仿真研究表明了这种方法比全局核和局部核分别单独用于步态学习时有优越性．SVM以踝关节及髋关节的轨迹作为输入,相应的满足ZMP判据的上体轨迹作为输出,利用有限的理想步态样本对机器人上体轨迹与腿部轨迹之间的动态运动关系进行学习,然后将训练好的SVM置入机器人控制系统,从而增强了步态控制的鲁棒性,有利于实现两足机器人在非结构环境下的稳定步行．仿真结果表明了所提方法的优越性．