基于对偶原理的二子样划船补偿算法

划船补偿算法一般以典型划船运动为基础,利用最优化理论来进行推导.圆锥补偿算法不仅可利用最优化理论,还可利用Goodman-Robinson理论进行推导.利用对偶原理,将Goodman-Robinson理论下得到的二子样修正圆锥补偿算法推广至划船补偿算法设计中,得到一种改进的二子样划船补偿算法.在典型划船运动条件下,对得到的划船补偿算法进行了数字仿真,并与二子样优化划船补偿算法进行了对比研究.仿真结果表明,此改进二子样划船补偿算法能提高速度更新精度.     

基于投影寻踪的高光谱图像异常检测并行算法

投影寻踪方法能有效提取数据中的非高斯结构凸显异常信息,但在求解最优投影方向时存在计算量大、运行时间长的问题,为提高处理效率,提出一种机群环境下的并行算法.选用偏度和峰度组合作为投影指标,将所有像素光谱作为特定投影方向集依次搜索,求解最优投影方向.在并行计算各候选方向投影指标时,分割图像数据分布存储于各机群结点,数据子块朝候选方向并行投影后,将指标计算式变形分解,使各结点在指标计算过程中所需数据均为本地数据,解决数据局部性问题,并采用一种"轮流作主"的机制提高算法负载均衡程度.利用实用型模块化高光谱仪数据在机群系统上进行测试,达到了较好的加速效果,表明该并行算法具有良好的并行性能.     

结构光三维视觉检测中光条图像处理方法研究

在结构光视觉检测系统中,光条中心的提取精度直接影响到整个测量系统的测量精度.光条图像的处理是其中重要的一步,尤其是受到严重噪声干扰的图像.探讨了被多种噪声干扰的光条图像的处理和精确提取光条中心的方法.给出了一种消除环境干扰的滤波模板并实验验证了其滤波效果.使用这些光条图像处理方法使整个测量系统在200mm×200mm的测量范围内测量精度达到0.083mm.      

基于FGN输入流的G/D/1排队模拟

传统的排队理论不适于分析高速网络表现出的自相似流量.通过实验仿真,主要考察平均等待时间和在队列分别为无限和有限情形下的队列尾部特征等参数,并对以FGN为输入流的G/D/1排队模型作了定性分析.结果表明在输入流的强度和方差基本相等且系统利用律大于某一阈值的情况下,队列平均等待时间随Hurst参数增大而显著增长.同时指出在相同的条件下考察队列尾部特征,具有有限队列长度的G/D/1排队模拟结果要远优于无限队列长度下的理论分析结果.      

Acceleration sensors based modal identification and active vibration control of flexible smart cantilever plate

Some flexible appendages of spacecrafts, such as solar panels, are cantilever plate structures. Thus, vibration problem is unavoidable when there is slewing maneuver or external disturbance excitation. Vibration of such cantilever plate structures includes coupled bending and torsional motion. Furthermore, the low amplitude vibration near the equilibrium point is very difficult to be quickly suppressed due to nonlinear factors of the hardware in the system, which is harmful to stability and attitude control accuracy. To solve these problems, acceleration sensor-based modal identification and active vibration control methods are presented for the first two bending and the first two torsional modes vibration of the cantilever plate. Optimal placements of three acceleration sensors and PZT patches actuators are performed to decouple the bending and torsional vibration of such cantilever plate for sensing and actuating, and identifications are achieved by experiments. A nonlinear control method is presented to suppress both high and low amplitude vibrations of flexible smart cantilever plate significantly. Experimental comparison researches are conducted by using acceleration proportional feedback and the presented nonlinear control algorithms. The experimental results demonstrate that the presented acceleration sensor-based methods can suppress the vibration of cantilever plate effectively.     

基于CDMA蜂窝网的飞行器三维定位算法

针对中低空飞行器提出了一种将码分多址(CDMA)蜂窝网导频信号被动定位与惯性导航系统进行组合的导航定位方法。该定位方法是根据CDMA蜂窝网导频信号的到达时差（TDOA）进行两次加权最小二乘解算,并利用飞行器惯性组合的原始信息进行解模糊,从而实现中低空飞行器的三维实时定位。蒙特卡罗仿真证明：在高斯白噪声条件下,该算法运算速度快,精度高,其均方误差逼近克拉美罗下界（CRLB）,为组合导航实时性要求提供了理论参考。     

Autonomous navigation of formation flying spacecrafts in deep space exploration and communication by hybrid navigation utilizing neural network filter

Autonomous navigation of spacecrafts is a difficult task, however, which is a must in future deep space exploration. With multiple spacecrafts flying in space, this aim can be achieved by formation flying spacecraft (FFS) utilizing inverse time difference of arrival (ITDOA) and inverse difference Doppler (IDD) methods, which can locate the position of earth-station from one-way uplink signals in the FFS coordinate, and by way of conversion of coordinates, the position of FFS is achieved in earth-centered earth-fixed (ECEF) coordinate. The ability of neural network (NN) filter in navigation to extract position of spacecrafts from random measuring noise of signal arrival time and Doppler shift is studied with different radius of FFS and surveying parameters. The NN filter used by spacecraft group is new way of unidirectional autonomous navigation and is of high precision of hybrid navigation.     

INS/SAR组合导航参数传递建模及精度分析

 对合成孔径雷达景象匹配辅助（INS/SAR）组合导航中地面合成孔径雷达(SAR)匹配点位置参数向飞行器主惯导中心的传递过程进行研究。分析了SAR匹配点位置传递过程中所涉及的各环节及其相互关系,以此为基础建立了测量参数传递过程数学模型,提出适合该模型的误差分析与精度估计方法,结合理论和实验结果对各测量参数误差所造成的传递误差进行分析和比较,得出单一测量参数误差影响程度的排序,并在此基础上得出总精度的估计值。参数传递模型及精度实验结果与实际情况相符,可为组合导航中合理的精度分配提供依据。     

基于样条曲线的机动弹头再入轨迹优化研究

使用三次样条函数拟合再入飞行器纵向运动轨迹,以样条曲线上的控制节点为优化参数,将再入轨迹优化问题转化为静态参数优化问题.最后以纵向平面内的最优轨迹为例,以终点速度最大和飞行时间最短为优化目标,采用基于Pareto定级排序遗传算法求解了在末端状态受约束的最优再入轨迹问题,验证了该方法的有效性.     

基于ICP算法的手术导航三维配准技术

针对计算机辅助手术三维导航技术中术前CT图像与术中实际空间的配准问题,提出一种基于最近点迭代(ICP,Iterative Closest Point)算法的特征点云配准技术.利用医学图像空间和实际空间特征区域的两片点云坐标进行三维配准.对CT图像进行重建、分割及交互式操作得到医学图像特征点云;利用光学定位仪实时采集实际空间中对应区域的点云;通过主元分析(PCA,Principal Component Analysis)获取两组点云数据的特征向量进行初配准;进行最近点迭代使配准矩阵收敛到一个最优解,其中采用k-d tree寻找邻近点加速迭代过程.以塑料脊柱模型骨为对象进行了脊柱手术导航配准精度实验,进一步对实验中的点云数据加入高斯噪声以进行误差分析.结果表明这种配准方法简单可靠,在模型骨情况下配准精度在1mm以内.