An LMS adaptive time delay estimation method with two windows is presented. This method can reduce the superfluous calculation greatly when the time of correlation is long. It is suitable for the time delay estimation...An LMS adaptive time delay estimation method with two windows is presented. This method can reduce the superfluous calculation greatly when the time of correlation is long. It is suitable for the time delay estimation of white band-limited random signals. The feasibility and the performances of this method are also studied.展开更多
The reconstruction control of modular self-reconfigurable spacecraft (MSRS) is addressed using an adaptive sliding mode control (ASMC) scheme based on time-delay estimation (TDE) technology. In contrast to the ground,...The reconstruction control of modular self-reconfigurable spacecraft (MSRS) is addressed using an adaptive sliding mode control (ASMC) scheme based on time-delay estimation (TDE) technology. In contrast to the ground, the base of the MSRS is floating when assembled in orbit, resulting in a strong dynamic coupling effect. A TED-based ASMC technique with exponential reaching law is designed to achieve high-precision coordinated control between the spacecraft base and the robotic arm. TDE technology is used by the controller to compensate for coupling terms and uncertainties, while ASMC can augment and improve TDE’s robustness. To suppress TDE errors and eliminate chattering, a new adaptive law is created to modify gain parameters online, ensuring quick dynamic response and high tracking accuracy. The Lyapunov approach shows that the tracking errors are uniformly ultimately bounded (UUB). Finally, the on-orbit assembly process of MSRS is simulated to validate the efficacy of the proposed control scheme. The simulation results show that the proposed control method can accurately complete the target module’s on-orbit assembly, with minimal perturbations to the spacecraft’s attitude. Meanwhile, it has a high level of robustness and can effectively eliminate chattering.展开更多
On account of the traditional multiple signal classification(MUSIC)algorithm has poor performance in time delay estimation under the condition of small sampling data and low SNR.In this paper,the traditional MUSIC alg...On account of the traditional multiple signal classification(MUSIC)algorithm has poor performance in time delay estimation under the condition of small sampling data and low SNR.In this paper,the traditional MUSIC algorithm is improved.The algorithm combines the idea of spatial smoothing,constructs a new covariance matrix using the covariance information of the measurement data,and constructs a weighted value using the modified noise eigenvalues to weight the traditional estimation spectrum.Simulation results show that the improved algorithm has steeper spectral peaks and better time delay resolution under the condition of inaccurate path number estimation.The time delay estimation accuracy of this algorithm is higher than that of the traditional MUSIC algorithm and the improved SSMUSIC algorithm under the conditions of small sampling data and low SNR.展开更多
随着先进工艺和技术的不断进步,要想保证数据在高速传输中的正确性,均衡器需要有更高的补偿和更低的功耗,才能实现高效通信。基于12 nm互补金属氧化物半导体工艺,设计了一种高增益、低功耗的自适应连续时间线性均衡器(continuous time l...随着先进工艺和技术的不断进步,要想保证数据在高速传输中的正确性,均衡器需要有更高的补偿和更低的功耗,才能实现高效通信。基于12 nm互补金属氧化物半导体工艺,设计了一种高增益、低功耗的自适应连续时间线性均衡器(continuous time linear equalizer,CTLE),该均衡器采用2级级联结构来补偿信道衰减,并提高接收信号的质量。此外,自适应模块通过采用符号-符号最小均方误差(sign-sign least mean square,SS-LMS)算法,使抽头系数加快了收敛速度。仿真结果表明,当传输速率为16 Gbit/s时,均衡器可以补偿-15.53 dB的半波特率通道衰减,均衡器系数在16×10^(4)个单元间隔数据内收敛,并且收敛之后接收误码率低于10^(-12)。展开更多
针对现有超声测厚系统精度较低的问题,研制基于最小均方(Least Mean Square,LMS)自适应时间延迟估计的高精度超声测厚系统。设计超声发射及接收电路,研发基于现场可编程门阵列(Field Programmable Gate Array,FPGA)的高速数据采集及传...针对现有超声测厚系统精度较低的问题,研制基于最小均方(Least Mean Square,LMS)自适应时间延迟估计的高精度超声测厚系统。设计超声发射及接收电路,研发基于现场可编程门阵列(Field Programmable Gate Array,FPGA)的高速数据采集及传输系统,开发基于MATLAB的上位机信号处理软件,通过LMS自适应时间延迟估计算法准确、高效地计算超声飞行时间(Time of Flight,TOF),从而实现高精度厚度测量。开展模拟回波仿真实验,结果显示:相较峰值法、包络法和相关法,LMS法在时间延迟估计方面更具优势。搭建基于LMS自适应时延估计的超声测厚系统,以量块为对象进行测厚实验,结果表明:该系统测厚相对误差小于3.77%,重复实验标准差不高于0.2μm,最大相对不确定度为1.4%。基于LMS自适应时延估计的超声测厚系统可应用于板材厚度测量等领域,有利于推动高精度超声测厚技术发展,具有重要技术借鉴价值。展开更多
文摘An LMS adaptive time delay estimation method with two windows is presented. This method can reduce the superfluous calculation greatly when the time of correlation is long. It is suitable for the time delay estimation of white band-limited random signals. The feasibility and the performances of this method are also studied.
基金This study was supported by the National Defense Science and Technology Innovation Zone of China(Grant No.00205501).
文摘The reconstruction control of modular self-reconfigurable spacecraft (MSRS) is addressed using an adaptive sliding mode control (ASMC) scheme based on time-delay estimation (TDE) technology. In contrast to the ground, the base of the MSRS is floating when assembled in orbit, resulting in a strong dynamic coupling effect. A TED-based ASMC technique with exponential reaching law is designed to achieve high-precision coordinated control between the spacecraft base and the robotic arm. TDE technology is used by the controller to compensate for coupling terms and uncertainties, while ASMC can augment and improve TDE’s robustness. To suppress TDE errors and eliminate chattering, a new adaptive law is created to modify gain parameters online, ensuring quick dynamic response and high tracking accuracy. The Lyapunov approach shows that the tracking errors are uniformly ultimately bounded (UUB). Finally, the on-orbit assembly process of MSRS is simulated to validate the efficacy of the proposed control scheme. The simulation results show that the proposed control method can accurately complete the target module’s on-orbit assembly, with minimal perturbations to the spacecraft’s attitude. Meanwhile, it has a high level of robustness and can effectively eliminate chattering.
文摘On account of the traditional multiple signal classification(MUSIC)algorithm has poor performance in time delay estimation under the condition of small sampling data and low SNR.In this paper,the traditional MUSIC algorithm is improved.The algorithm combines the idea of spatial smoothing,constructs a new covariance matrix using the covariance information of the measurement data,and constructs a weighted value using the modified noise eigenvalues to weight the traditional estimation spectrum.Simulation results show that the improved algorithm has steeper spectral peaks and better time delay resolution under the condition of inaccurate path number estimation.The time delay estimation accuracy of this algorithm is higher than that of the traditional MUSIC algorithm and the improved SSMUSIC algorithm under the conditions of small sampling data and low SNR.
文摘随着先进工艺和技术的不断进步,要想保证数据在高速传输中的正确性,均衡器需要有更高的补偿和更低的功耗,才能实现高效通信。基于12 nm互补金属氧化物半导体工艺,设计了一种高增益、低功耗的自适应连续时间线性均衡器(continuous time linear equalizer,CTLE),该均衡器采用2级级联结构来补偿信道衰减,并提高接收信号的质量。此外,自适应模块通过采用符号-符号最小均方误差(sign-sign least mean square,SS-LMS)算法,使抽头系数加快了收敛速度。仿真结果表明,当传输速率为16 Gbit/s时,均衡器可以补偿-15.53 dB的半波特率通道衰减,均衡器系数在16×10^(4)个单元间隔数据内收敛,并且收敛之后接收误码率低于10^(-12)。
文摘针对现有超声测厚系统精度较低的问题,研制基于最小均方(Least Mean Square,LMS)自适应时间延迟估计的高精度超声测厚系统。设计超声发射及接收电路,研发基于现场可编程门阵列(Field Programmable Gate Array,FPGA)的高速数据采集及传输系统,开发基于MATLAB的上位机信号处理软件,通过LMS自适应时间延迟估计算法准确、高效地计算超声飞行时间(Time of Flight,TOF),从而实现高精度厚度测量。开展模拟回波仿真实验,结果显示:相较峰值法、包络法和相关法,LMS法在时间延迟估计方面更具优势。搭建基于LMS自适应时延估计的超声测厚系统,以量块为对象进行测厚实验,结果表明:该系统测厚相对误差小于3.77%,重复实验标准差不高于0.2μm,最大相对不确定度为1.4%。基于LMS自适应时延估计的超声测厚系统可应用于板材厚度测量等领域,有利于推动高精度超声测厚技术发展,具有重要技术借鉴价值。
