A novel method for noise removal from the rotating accelerometer gravity gradiometer(MAGG)is presented.It introduces a head-to-tail data expansion technique based on the zero-phase filtering principle.A scheme for det...A novel method for noise removal from the rotating accelerometer gravity gradiometer(MAGG)is presented.It introduces a head-to-tail data expansion technique based on the zero-phase filtering principle.A scheme for determining band-pass filter parameters based on signal-to-noise ratio gain,smoothness index,and cross-correlation coefficient is designed using the Chebyshev optimal consistent approximation theory.Additionally,a wavelet denoising evaluation function is constructed,with the dmey wavelet basis function identified as most effective for processing gravity gradient data.The results of hard-in-the-loop simulation and prototype experiments show that the proposed processing method has shown a 14%improvement in the measurement variance of gravity gradient signals,and the measurement accuracy has reached within 4E,compared to other commonly used methods,which verifies that the proposed method effectively removes noise from the gradient signals,improved gravity gradiometry accuracy,and has certain technical insights for high-precision airborne gravity gradiometry.展开更多
在对变步长归一化最小均方误差(Variable step size normalized least mean square,VSS-NLMS)的几种算法以及各个算法在远端和双端通话模式下的性能分析比较的基础上,对NEW-NPVSS(NEW non-parametricVSS)算法进行了改进。在双端通话的...在对变步长归一化最小均方误差(Variable step size normalized least mean square,VSS-NLMS)的几种算法以及各个算法在远端和双端通话模式下的性能分析比较的基础上,对NEW-NPVSS(NEW non-parametricVSS)算法进行了改进。在双端通话的情况下改进算法具有更好的收敛性;然后提出了基于滤波器系数梯度的变步长新算法,当滤波器系数梯度小于门限值时,采用固定步长更新滤波器系数。反之,则停止更新滤波器系数,并且用远端模式下的系数替代当前系数。仿真结果表明所提出的算法在远端通话模式下比其他VSS-NLMS算法具有更好的收敛性,在双端情况下具有比固定步长NLMS(Normalized least mean square)和SVSS(Simple VSS)更好的收敛性。展开更多
在低纹理场景中,基于点特征的同时定位与地图构建(Simultaneous Localization and Mapping,SLAM)算法很难追踪足够多的有效特征点,系统甚至无法正常工作.众所周知,丰富的线段特征存在在人造结构化环境中的地面与墙面交界处.因此,提出一...在低纹理场景中,基于点特征的同时定位与地图构建(Simultaneous Localization and Mapping,SLAM)算法很难追踪足够多的有效特征点,系统甚至无法正常工作.众所周知,丰富的线段特征存在在人造结构化环境中的地面与墙面交界处.因此,提出一种点线特征融合的双目视觉SLAM算法.在特征提取前,引入梯度密度滤波器加速线特征提取和提高线匹配的准确度,在特征点匹配阶段,采用渐进采样一致性(Progressive Sampling Consensus,PROSAC)算法剔除误匹配点,从而提高定位精度.此外,在特征的融合过程中引入加权思想.在构造误差函数时对点线特征权重进行合理分配.最后,通过在公开的数据集上得到的仿真并与一些优秀的算法进行对比,该算法性能优于PL-SLAM和LSD-SLAM算法,证明了算法的有效性和准确性.展开更多
The non-linearity problem of aircraft system could not be overcome by using the MEMS sensor only.In order to improve the accuracy of aerial vehicle attitude,an aircraft attitude estimation of the MEMS sensor based on ...The non-linearity problem of aircraft system could not be overcome by using the MEMS sensor only.In order to improve the accuracy of aerial vehicle attitude,an aircraft attitude estimation of the MEMS sensor based on modified particle filter is proposed.The aircraft attitude is optimized by the conjugate gradient method,and the drift error of gyroscope is reduced.Moreover,the particle weight is updated by the observed value to obtain an optimized state estimate.Finally,the conjugate gradient method and the modified particle filter are weightily combined to determine the optimal weighting factor.The attitude estimation is carried out with STM32 and MEMS sensor as the core to design system.The experimental results show that the static and dynamic attitude estimation performances of the aircraft are improved.The performances are well,the attitude data is relatively stable,and the tracking characteristics are better.Moreover,it has better robustness and stability.展开更多
We design a channel-drop filter(CDF)with a linear gradient microcavity in a two-dimensional(2D)photonic crystal(PC).The model of three-port CDF with reflector is used to achieve high quality factor(Q-factor)and 100%ch...We design a channel-drop filter(CDF)with a linear gradient microcavity in a two-dimensional(2D)photonic crystal(PC).The model of three-port CDF with reflector is used to achieve high quality factor(Q-factor)and 100%channel-drop efficiency.The research indicates that adjusting the distance between reference plane and reflector can simultaneously influence the Q-factor due to coupling to a bus waveguide and the phase retardation occurring in the round trip between a microcavity and a reflector.The calculation results of 2D finite-difference time-domain(FDTD)method show that the designed filter can achieve the drop efficiency of 96.7%and ultra-high Q-factor with an ultra-small modal volume.展开更多
文摘A novel method for noise removal from the rotating accelerometer gravity gradiometer(MAGG)is presented.It introduces a head-to-tail data expansion technique based on the zero-phase filtering principle.A scheme for determining band-pass filter parameters based on signal-to-noise ratio gain,smoothness index,and cross-correlation coefficient is designed using the Chebyshev optimal consistent approximation theory.Additionally,a wavelet denoising evaluation function is constructed,with the dmey wavelet basis function identified as most effective for processing gravity gradient data.The results of hard-in-the-loop simulation and prototype experiments show that the proposed processing method has shown a 14%improvement in the measurement variance of gravity gradient signals,and the measurement accuracy has reached within 4E,compared to other commonly used methods,which verifies that the proposed method effectively removes noise from the gradient signals,improved gravity gradiometry accuracy,and has certain technical insights for high-precision airborne gravity gradiometry.
文摘在对变步长归一化最小均方误差(Variable step size normalized least mean square,VSS-NLMS)的几种算法以及各个算法在远端和双端通话模式下的性能分析比较的基础上,对NEW-NPVSS(NEW non-parametricVSS)算法进行了改进。在双端通话的情况下改进算法具有更好的收敛性;然后提出了基于滤波器系数梯度的变步长新算法,当滤波器系数梯度小于门限值时,采用固定步长更新滤波器系数。反之,则停止更新滤波器系数,并且用远端模式下的系数替代当前系数。仿真结果表明所提出的算法在远端通话模式下比其他VSS-NLMS算法具有更好的收敛性,在双端情况下具有比固定步长NLMS(Normalized least mean square)和SVSS(Simple VSS)更好的收敛性。
基金National Natural Science Foundation of China(No.61261029)
文摘The non-linearity problem of aircraft system could not be overcome by using the MEMS sensor only.In order to improve the accuracy of aerial vehicle attitude,an aircraft attitude estimation of the MEMS sensor based on modified particle filter is proposed.The aircraft attitude is optimized by the conjugate gradient method,and the drift error of gyroscope is reduced.Moreover,the particle weight is updated by the observed value to obtain an optimized state estimate.Finally,the conjugate gradient method and the modified particle filter are weightily combined to determine the optimal weighting factor.The attitude estimation is carried out with STM32 and MEMS sensor as the core to design system.The experimental results show that the static and dynamic attitude estimation performances of the aircraft are improved.The performances are well,the attitude data is relatively stable,and the tracking characteristics are better.Moreover,it has better robustness and stability.
基金supported by the Natural Science Foundation of the Higher Education Institutions of Guangxi Province in China(No.201202ZD010)
文摘We design a channel-drop filter(CDF)with a linear gradient microcavity in a two-dimensional(2D)photonic crystal(PC).The model of three-port CDF with reflector is used to achieve high quality factor(Q-factor)and 100%channel-drop efficiency.The research indicates that adjusting the distance between reference plane and reflector can simultaneously influence the Q-factor due to coupling to a bus waveguide and the phase retardation occurring in the round trip between a microcavity and a reflector.The calculation results of 2D finite-difference time-domain(FDTD)method show that the designed filter can achieve the drop efficiency of 96.7%and ultra-high Q-factor with an ultra-small modal volume.
