多旋翼无人机的电机关键参数确定方法

通过直流电动机模型推导出PWM波的占空比与电机转速的模型,根据功率守恒方程和上述模型得出电机内阻、反电动势、自身力矩系数和螺旋翼的升力系数的计算方法.通过试验的方法测试安装有螺旋翼电动机的输入电流有效值、占空比和转速,并计算电动机的参数,最后带入到占空比与电机转速的关系模型中,验证以上推导出的模型和计算方法的合理性.结果表明模型的相对误差在3％左右.     

Three-dimensional analysis of relationship between relative orientation and motion modes

Target motion modes have a close relationship with the relative orientation of missile-totarget in three-dimensional highly maneuvering target interception. From the perspective of relationship between the sensor coordinate system and the target body coordinate system, a basic model of sensor is stated and the definition of relative angular velocity between the two coordinate systems is introduced firstly. Then, the three-dimensional analytic expressions of relative angular velocity for different motion modes are derived and simplified by analyzing the influences of target centroid motion, rotation around centroid and relative motion. Finally, the relationships of the relative angular velocity directions and values with motion modes are discussed. Simulation results validate the rationality of the theoretical analysis. It is demonstrated that there are significant differences of the relative orientation in different motion modes which include luxuriant information about motion modes. The conclusions are significant for the research of motion mode identification,maneuver detection, maneuvering target tracking and interception using target signatures.     

基于固定阈值事件触发扩张状态观测器的多智能体协同目标环绕控制

针对复杂多扰环境下面向未知运动目标的多智能体对峙跟踪问题,提出了一种基于固定阈值事件触发扩张状态观测器(FTESO)的多智能体协同目标环绕控制方法.首先,建立了智能体与目标的相对运动模型,将目标加速度、模型非线性、环境摄动视为集总干扰,利用量测的相对位置信息构造可降低测量端状态更新频次的FTESO,以实现在非周期采样条...     

无人直升机视觉着陆中的运动状态估计算法

对无人直升机(UH)视觉着陆中基于视觉图像处理的运动状态估计问题进行了研究。介绍了视觉着陆原理,分析了运动估计、特征图像处理与着陆控制间的关系,推导并建立了UH相对着陆平台位姿估计算法、线速度与角速度估计算法。相邻两帧图像对应特征点像点位置为位姿估计算法提供数据,一帧图像特征点像点位置及其对应像点平移速度为线速度与角速度估计算法提供数据。利用UH着陆控制仿真数据模拟UH着陆运动过程中像点位置及其对应平移速度的视觉图像处理结果。仿真验证了运动状态估计算法,结果表明所提出的运动状态估计算法能有效地利用视觉图像处理结果数据估计出UH的位置、姿态、线速度和角速度。     

Results from a Four-Element Adaptive Antenna Experiment

Experimental results from a four-element, linear, half-wavelength spacing, adaptive-array antenna under the control of the least mean square (LMS) algorithm are presented. The array is found to be capable of nulling a 70-MHz signal to -35 dB below a desired signal over a 5-MHz bandwidth. The antenna processing gain is constant over a desired signal-to-jammer signal power ratio range from -20 dB to 5 dB. A sharp reduction in processing gain is observed for angular separations between jammer and desired signal of less than 10°. Antenna patterns taken with weights set in 300 iterations of the LMS algorithm show that the one strong, one weak jammer combination has a longer weight convergence time and reduced processing gain compared with a two strong jammers combination. Contours of constant desired signal-to-jammer signal power ratio, after adaptive antenna processing, reveal a complex shape for communication between air and ground due to the finite angular resolution of the adaptive antenna.     

利用能量/动量飞轮的偏置动量姿态控制系统

研究偏置动量姿态控制系统中的集成能量与姿态控制问题。利用一对正 反转飞轮提供偏置角动量并同时储 /放能以满足星载设备的能源需求。滚动 /偏航运动由俯仰轴磁矩控制。设计了力矩形式的飞轮的控制律 ,使之提供期望的俯仰控制力矩 ,并以给定的功率储 /放能。保持两只飞轮正 反转可以完全避免飞轮控制律中的系统奇异。提出了利用动能反馈的飞轮储能功率规划方案 ,以使系统维持能量平衡 ,避免由于能量过剩引起的飞轮饱和。飞轮的最小转动惯量受最大偏置角动量和最小能量的限制 ,结合几何方法对这种限制条件进行了分析。数值仿真结果证明了控制方案的有效性。     

MIMO radar: snake oil or good idea?

MIMO communication is theoretically superior to conventional communication under certain conditions, and MIMO communication also appears to be practical and cost-effective in the real world for some applications. It is natural to suppose that the same is true for MIMO radar, but the situation is not so clear. Researchers claim many advantages of MIMO radar relative to phased array radars (e.g., better detection performance, better angular resolution, better angular measurement accuracy, improved robustness against RFI, ECM, multipath, etc.). We will evaluate such assertions from a system engineering viewpoint. In particular, there are serious trade-offs of MIMO vs. phased array radars relative to cost, system complexity, and risk considering numerous real world effects that are not included in most theoretical analyses. Moreover, in many cases one can achieve essentially the same radar system improvement with phased array radars using simpler, less expensive, and less risky algorithms. We evaluate roughly a dozen asserted advantages of MIMO radar relative to phased arrays.     

单框架控制力矩陀螺群的奇异几何分析

使用几何方法对单框架控制力矩陀螺群（包括转子恒速的CSCMG和转子变速的VSCMG）的奇异性进行了分析。通过绘制CSCMG的奇异角动量超曲面,并标识隐奇异和显奇异在该曲面上对应的点,直观地表述了CSCMG的可操纵空间,得出星体三轴角动量可交换的具体范围。比较奇异角动量超曲面图,可以看出金字塔构型在角动量饱和包络面内部存在显奇异,而五棱锥构型的显奇异十分接近饱和包络面。文中分析了金字塔和五棱锥两种构型的CSCMG可能的退化隐奇异点,并给出了退化隐奇异点在奇异角动量超曲面上的具体位置及其高斯曲率特性。对集成的能量和姿态一体化控制系统（IPACS）可能出现的无法操纵的情况进行了补充分析,给出了使用VSCMG的IPACS不会出现操纵奇异的构型设计的充分条件。给出在某一瞬时能量下,VSCMG转子角速率范围有限制时的角动量包络图,从中得到CSCMG与VSCMG角动量体的变化和联系。     

基于双频激光干涉仪的角速率检测系统精度分析

为了能够精确检测到测试转台在低速运行下的角速率,设计了一种基于双频激光干涉仪的角速率精度检测系统.首先,对本检测系统各项误差进行机理分析.然后,综合各项误差项建立总体相对误差模型.最终,通过仿真分析得到各个误差因子对相对误差项的影响,为保证检测系统相对精度提供理论依据,能够满足对高精度惯性器件测试转台低速段0.0001(°)/s~1(°)/s速率检测要求.     

Microsatellite combined attitude/energy systems

We have constructed a high-temperature super conductor-magnet momentum wheel for microsatellites and propose a micro high-temperature superconductor energy storage and attitude control system for nano/pico satellites. The momentum wheel for micro satellites has a mass of 1.1 kg with an angular momentum capacity of 3.5 J sec. It occupies a volume of 12.7 cm in diameter and 5 cm in height. It operates within the restricted power budget of a microsatellite with a total power supply of only 10 watts. It consumes less than 1 watt for sustenance. The micro high-temperature superconductor flywheel for nano/pico satellites has an angular momentum capacity of 0.083 Js and stores 2.32 kJ at 530 krpm. Its energy storage capacity is approximately 45 Wh/kg with an energy density of around 370 kJ/L. The HTS systems can perform the dual function of a power/attitude control system and are ideally suited for low Earth orbit energy storage, power generation, and attitude control of spacecraft.     

航天器有限时间输出反馈姿态控制

研究在角速度不可测时航天器的有限时间姿态控制问题。基于有限时间控制技术,提出了由修正Rodrigues参数进行姿态描述的航天器输出反馈姿态控制算法。首先设计了单个航天器的输出反馈姿态控制器,在没有角速度反馈时也能够保证航天器姿态在有限时间内调节到期望姿态。之后,设计了无需绝对角速度和相对角速度信息的多航天器分布式输出反馈姿态控制器。使用Lyapunov理论和图论,对闭环系统全局有限时间稳定性进行了严格的证明。最后对提出的控制算法进行了数值仿真,其结果验证了所设计的航天器输出反馈控制算法的可行性和有效性。     

基于输出反馈的柔性航天器变结构跟踪控制方法

为解决柔性航天器姿态机动的控制问题,给出了基于输出反馈的变结构跟踪控制算法。针对柔性航天器的大角度机动,在建立了柔性航天器相对参考轨迹的动力学方程的基础上,设计了仅利用航天器本体的角度和角速度信息的变结构跟踪控制器,使得姿态状态跟踪误差(包括姿态跟踪误差和姿态角速度跟踪误差)以及挠性附件的模态变量从任意的初始状态出发都会到达包含原点的一个闭集内,并且姿态状态跟踪误差能收敛到零,并给出了严格的数学证明。仿真结果证明了所提控制方法的可行性和有效性。     

Rank detector preprocessor for glint reduction in a tracking radar

A rank detector is used to detect instantaneous received power fades in a tracking radar. On detection of a fade, censorship of the angular position measurement is implemented in a Kalman tracking filter. It is shown that this technique can typically give a 15% angular tracking improvement on highly dynamic targets     

利用变速控制力矩陀螺的航天器集成能量与姿态控制

 利用变速控制力矩陀螺(VSCMG)的航天器姿态与能量一体化控制问题。针对以VSCMG为姿态控制执行机构的刚体航天器设计了全局渐近稳定的姿态跟踪控制律。将VSCMG的框架角速度和转子角加速度作为控制输入向量设计操纵律。利用加权的最小范数解得到VSCMG的姿态控制输入向量,并用与之正交的控制输入向量来以给定的功率存储/释放能量。提出了同时表征力矩陀螺模式构型奇异和转子轮速平衡的混合指标函数。对控制自由度有冗余的系统,在混合指标函数的基础上利用梯度法构建了VSCMG的空转运动,以回避力矩陀螺模式的构型奇异,并同时减小转子转速差过大引起的转速饱和以及VSCMG零奇异的可能性。利用反馈转子动能的方法规划日照期间的储能功率,以维持系统长时间工作的能量平衡。基于某太阳同步轨道卫星的数值仿真结果验证了系统的有效性。     

考虑非高斯相关噪声的视线角速率提取算法

针对捷联导引头敏感信息存在非高斯噪声且状态噪声与观测噪声相关的问题,提出了修正球面坐标系下带有相关噪声解耦的扩展椭球集员滤波（ESMF）算法。首先,通过对弹目相对距离及其变化率的规范化处理,得到修正球面坐标系下的视线角速率提取模型;然后,利用相关噪声解耦方法去除观测方程中耦合的状态噪声项,基于泰勒级数展开推导了相关噪声解耦后的模型线性化表达式,得到包含线性化误差的虚拟噪声椭球集合,并根据最小迹和最小化尺度因子上界的优化方法得到状态更新与观测更新椭球,形成非高斯相关噪声解耦的扩展椭球集员滤波算法。仿真结果表明,所提算法能够在考虑非高斯相关噪声的情况下,实现捷联导引头视线角速率的高精度提取。     

Controlling Stationary Satellite Orbits Minimum Fuel Consumption Rate

The orbital angular velocity of a stationary satellite expresses the perturbation in the orbit of the satellite. The minimum variation in direction of this velocity corresponds to the minimum fuel consumption rate to maintain a stationary satellite within allocated bounds. The directional variation of the orbital angular velocity is minimized by maintaining the ascending node of the orbit near the direction of the vernal equinox. The direction of the ascending node to maintain the orbit with minimum fuel consumption rate is given over the 18.6 yr nodal period of the moon. Over that period the inclination variation of the orbit and the angular speed proportional to the necessary fuel consumption rate to maintain the orbit are also given. An example of fuel consumption is given with a comparison with fuel savings over the standard stationkeeping method. The method here is applicable to the geostationary communication satellite, UHF broadcasting satellite, solar power satellite, etc.     

基于导航姿态解算的光纤陀螺平台低频角振动测试方法研究CSCD

为准确评价光纤陀螺平台的低频角振动特性,提出了一种基于导航姿态解算的光纤陀螺平台低频角振动测试方法。首先,通过角振动台精确模拟载体的低频角振动状态,并通过光纤陀螺平台飞行导航过程中的断调平差分信号,实现平台框架角度信号与角振动台激励角度信号的数据同步;然后,利用平台式惯导系统的导航姿态解算方法,实时解算低频角振动过程中光纤陀螺平台的台体姿态,并通过坐标系转换得到平台基座系相对于地理系的实时姿态;最后,通过对光纤陀螺平台稳定回路的幅相特性分析,得到低频角振动激励下稳定回路的幅值和相位特性,实现对光纤陀螺平台角动态特性的准确评估。     

基于SOA的光纤陀螺相对强度噪声抑制研究

为进一步提高光纤陀螺精度,抑制掺铒光纤光源的相对强度噪声(RIN),在利用半导体光放大器(SOA)对光源相对强度噪声进行抑制的基础上,实现了SOA光源一体化方案。经过原理分析并设计实验方案,对比实验前后的测试数据可以看出:处于增益饱和状态的半导体光放大器对光源相对强度噪声起到了抑制作用,抑制后陀螺的零偏稳定性由之前的千分之一提高到万分之五左右,精度提高1倍,随机游走系数减小到56%;另一方面,一体化方案的实现,使利用SOA抑制强度噪声的方案更易实现,操作更简单,有利于该项技术的进一步工程应用。     

Angular Tracking of Two Closely Spaced Radar Targets

Bounds on the accuracy of unbiased estimates of the angular coordinates of a target, in the presence of a nearby interfering target, have previously been determined. These bounds allow for the angular resolution of two CW targets to an extent limited only by the signal-to-noise ratio (SNR). An SNR of 40 dB will allow two targets to be resolved at less than one-fifth beamwidth (?/2 X) separation, for most values of target relative phase angles. The maximum-likelihood estimator for this problem, based on the outputs of a plane circular array of receiving elements, is found and simplified. An analog realization of the two-target maximum-likeli-hood processor is presented. This realization has the simple form of two single-target trackers each tracking one of the targets, linked by a decoupling network which accounts for the interference produced in each by the presence of a second target, when the targets are separated by less than a beamwidth. Results of an analog-computer simulation of the system are given and discussed. Finally an application to the finite-size single-target problem is given.     

捷联惯性导航传统比力积分算法与对偶四元数算法的比较研究

捷联惯性导航速度更新算法中,将载体坐标系中的比力积分增量变换到导航参考坐标系中,载体姿态变化的影响通常采用一阶近似模型进行计算。本文分析了包括角振动和加速运动的动态运动下一阶近似模型的局限,在典型角振动及加速运动条件下对忽略姿态变化二阶项造成的速度更新误差进行了理论分析。通过比较,揭示了对偶四元数比力积分算法精度高于传统比力积分算法的原因,即和传统比力积分算法相比,对偶四元数比力积分算法等价于考虑了载体姿态变化影响的二阶项。通过典型角振动及加速运动条件下传统捷联惯性导航算法和对偶四元数导航算法的仿真比较,对理论分析结果进行了验证。