An integrated approach that considers the performance limitations of tracking control systems for air-breathing hypersonic vehicles is proposed. First, a set of ascent trajectories is obtained as candidates for tracki...An integrated approach that considers the performance limitations of tracking control systems for air-breathing hypersonic vehicles is proposed. First, a set of ascent trajectories is obtained as candidates for tracking control through a trajectory design method that considers the available acceleration. Second, the basic theory of performance limitations, which is adopted to calculate the limits on control performance through the trajectory, is integrated. The openloop dynamics of air-breathing hypersonic vehicles is responsible for these limits on the control system. Comprehensive specifications on stability, tracking accuracy, and robustness are derived, and the flight envelope with constraints and control specifications is identified. Simulation results suggest that trajectory design should consider restrictions on control performance to obtain reliable solutions.展开更多
针对主瓣干扰(main-lobe jamming,MLJ)在空域与有用信号(signal of interest,SOI)高度相关而难以被有效抑制的问题,基于跳变编码波形的抗MLJ系统通过对波形进行编码调制,接收端据此重构接收信号,利用码-空映射等效改变SOI空域信道,实现...针对主瓣干扰(main-lobe jamming,MLJ)在空域与有用信号(signal of interest,SOI)高度相关而难以被有效抑制的问题,基于跳变编码波形的抗MLJ系统通过对波形进行编码调制,接收端据此重构接收信号,利用码-空映射等效改变SOI空域信道,实现SOI与干扰信号在空域的分辨。但理论分析发现,信号带宽的增大将掩盖编码特征并使该方法失效。为此,利用多抽头系统的时-频映射特质,通过多抽头结构设计降低带宽掩盖,重新凸显编码特征。仿真结果显示,所提方法可在10 MHz的全带宽内,使干扰对消比大于20 dB,SOI对消比小于3 dB,具有较好的抗主瓣非零带宽干扰性能。展开更多
针对现有环境感知技术在毫米波通信信号带宽受限条件下的性能表现尚未得到充分研究,且在复杂场景下存在计算复杂度高、实时性不足等问题,提出一种基于有限带宽毫米波通信信号的主动式环境地图构建算法,旨在实现环境地图的实时构建,从而...针对现有环境感知技术在毫米波通信信号带宽受限条件下的性能表现尚未得到充分研究,且在复杂场景下存在计算复杂度高、实时性不足等问题,提出一种基于有限带宽毫米波通信信号的主动式环境地图构建算法,旨在实现环境地图的实时构建,从而提升通信系统的性能.首先,通过在移动端主动式自发自收毫米波通信信号,并获取回波的传播时延和角度信息,结合移动端姿态信息初步感知障碍物的坐标;其次,考虑毫米波通信信号有限带宽对地图分辨率的影响,采用栅格地图算法表征障碍物的空间位置,基于Bresenham算法计算空闲栅格,进而快速准确地构建环境地图,并通过设置不同的地图分辨率,进行了仿真实验,以分析不同地图分辨率条件下的地图构建结果;再次,统计并拟合了感知环境中到达角(Angle Of Arrival,AOA)的分布,以验证冯米塞斯(von Mises)分布的合理性;最后,将结果与基于激光雷达的基准地图进行对比,使用均方根误差(Root Mean Square Error,RMSE)验证精度,使用Jaccard相似度分析验证障碍物形状,并结合代码运行时长评估了算法的效率和系统性能.研究结果表明:所提算法在3GHz带宽和25格/米分辨率下,地图构建达到最优性能,其中RMSE为9.2943,Jaccard系数为0.6254,代码运行时长为14.7746 min,能够满足实时环境感知的需求;与500 MHz带宽和25格/米分辨率下的地图构建结果相比,RMSE、Jaccard系数、代码运行时长分别提升了56.1%、394.4%、70.6%.研究结果可以为未来高动态通信系统发展提供参考.展开更多
针对网络控制系统(Networked Control System,NCS)中普遍存在的有限带宽和信息量化问题,采用基于模型的控制策略,研究了量化状态反馈下一类网络控制系统的稳定性。分析了量化误差、更新时间、模型误差对系统稳定性的影响,并给出了系统...针对网络控制系统(Networked Control System,NCS)中普遍存在的有限带宽和信息量化问题,采用基于模型的控制策略,研究了量化状态反馈下一类网络控制系统的稳定性。分析了量化误差、更新时间、模型误差对系统稳定性的影响,并给出了系统模型状态、对象状态的稳定域范围。仿真结果表明了结论的正确性。展开更多
基金supported by Aerospace Science and Technology Innovation Fund of China (No. CASC2016)Six Talent Peaks Project in Jiangsu Province of China (KTHY025)+3 种基金Funding of Jiangsu Innovation Program for Graduate Educationthe National Natural Science Foundation of China (Nos. 61403191, 11572149)the Funding of Jiangsu Innovation Program for Graduate Education of China (Nos. KYLX_0281, KYLX15_0318 and NZ2015205)the Fundamental Research Funds for the Central Universities of China
文摘An integrated approach that considers the performance limitations of tracking control systems for air-breathing hypersonic vehicles is proposed. First, a set of ascent trajectories is obtained as candidates for tracking control through a trajectory design method that considers the available acceleration. Second, the basic theory of performance limitations, which is adopted to calculate the limits on control performance through the trajectory, is integrated. The openloop dynamics of air-breathing hypersonic vehicles is responsible for these limits on the control system. Comprehensive specifications on stability, tracking accuracy, and robustness are derived, and the flight envelope with constraints and control specifications is identified. Simulation results suggest that trajectory design should consider restrictions on control performance to obtain reliable solutions.
文摘针对现有环境感知技术在毫米波通信信号带宽受限条件下的性能表现尚未得到充分研究,且在复杂场景下存在计算复杂度高、实时性不足等问题,提出一种基于有限带宽毫米波通信信号的主动式环境地图构建算法,旨在实现环境地图的实时构建,从而提升通信系统的性能.首先,通过在移动端主动式自发自收毫米波通信信号,并获取回波的传播时延和角度信息,结合移动端姿态信息初步感知障碍物的坐标;其次,考虑毫米波通信信号有限带宽对地图分辨率的影响,采用栅格地图算法表征障碍物的空间位置,基于Bresenham算法计算空闲栅格,进而快速准确地构建环境地图,并通过设置不同的地图分辨率,进行了仿真实验,以分析不同地图分辨率条件下的地图构建结果;再次,统计并拟合了感知环境中到达角(Angle Of Arrival,AOA)的分布,以验证冯米塞斯(von Mises)分布的合理性;最后,将结果与基于激光雷达的基准地图进行对比,使用均方根误差(Root Mean Square Error,RMSE)验证精度,使用Jaccard相似度分析验证障碍物形状,并结合代码运行时长评估了算法的效率和系统性能.研究结果表明:所提算法在3GHz带宽和25格/米分辨率下,地图构建达到最优性能,其中RMSE为9.2943,Jaccard系数为0.6254,代码运行时长为14.7746 min,能够满足实时环境感知的需求;与500 MHz带宽和25格/米分辨率下的地图构建结果相比,RMSE、Jaccard系数、代码运行时长分别提升了56.1%、394.4%、70.6%.研究结果可以为未来高动态通信系统发展提供参考.
文摘针对网络控制系统(Networked Control System,NCS)中普遍存在的有限带宽和信息量化问题,采用基于模型的控制策略,研究了量化状态反馈下一类网络控制系统的稳定性。分析了量化误差、更新时间、模型误差对系统稳定性的影响,并给出了系统模型状态、对象状态的稳定域范围。仿真结果表明了结论的正确性。
