In this paper,an integrated guidance and control method based on an adaptive path-following controller is proposed to control a spin-stabilized projectile with only translational motion information under the constrain...In this paper,an integrated guidance and control method based on an adaptive path-following controller is proposed to control a spin-stabilized projectile with only translational motion information under the constraint of an actuator,uncertainties in aerodynamic parameters and measurements,and control system complexity.Owing to the fairly high rotation speed,the dynamic model of this missile is strongly nonlinear,uncertain and coupled in pitch,yaw and roll channels.A theoretical equivalent resultant force and uncertainty compensation method are comprehensively used to realize decoupling of pitch and yaw.In response to the strong nonlinear and time-varying characteristics of the dynamic system,the quasi-linear model whose parameters are obtained by interpolation of points selected as the segmentation points in the trajectory envelope,is used for calculation in each step.To cope with the system uncertainty caused by model approximation,parameter uncertainty and ballistic interference,an extended state estimator is used to compensate the output feedback according to the test ballistic angle.In order to improve the tracking efficiency and ensure the tracking error convergence with only translational motion information,the virtual guide point,whose derivative is deduced according to the Lyapunov principle,is calculated in real time according to the projection relationship between the real-time position and the reference trajectory,and a virtual line-of-sight angle and the backstepping method are used for the design of the guidance and control system.In order to avoid the influence of control input saturation on the guidance and control performance due to the actuator limitation and improve the robustness of the system,an anti-saturation compensator is designed according to the two-step method.The feasibility and effectiveness of the path-following controller is verified through closed-loop flight simulations with measurement,control,and condition uncertainties.The results indicate that the designed controller can converge to the reference path and evidently decrease the distance between the impact point and target under different uncertainties.展开更多
MapReduce是一个流行的并行处理大规模数据计算模型.为提升异构环境下的MapReduce性能,提出一种异构环境下基于节点作业时间感知的动态MapReduce调度策略:DTHE(Dynamic Map Reduce scheduling based on the Time-aware of node jobs in ...MapReduce是一个流行的并行处理大规模数据计算模型.为提升异构环境下的MapReduce性能,提出一种异构环境下基于节点作业时间感知的动态MapReduce调度策略:DTHE(Dynamic Map Reduce scheduling based on the Time-aware of node jobs in Heterogeneous Environments).DTHE在作业执行前,首先标记部分任务作为节点样本任务并优先处理,在执行其他任务时分析样本任务,预测节点性能和数据分布特征,动态采取相应的调度策略;在作业运行中实时监测节点任务状态,提前拉取节点下一个任务数据到本地内存.实验结果表明:在异构环境下,DTEH能够缩短5.1%的作业执行时间并减少磁盘I/O,有效提升MapReduce性能.展开更多
文摘In this paper,an integrated guidance and control method based on an adaptive path-following controller is proposed to control a spin-stabilized projectile with only translational motion information under the constraint of an actuator,uncertainties in aerodynamic parameters and measurements,and control system complexity.Owing to the fairly high rotation speed,the dynamic model of this missile is strongly nonlinear,uncertain and coupled in pitch,yaw and roll channels.A theoretical equivalent resultant force and uncertainty compensation method are comprehensively used to realize decoupling of pitch and yaw.In response to the strong nonlinear and time-varying characteristics of the dynamic system,the quasi-linear model whose parameters are obtained by interpolation of points selected as the segmentation points in the trajectory envelope,is used for calculation in each step.To cope with the system uncertainty caused by model approximation,parameter uncertainty and ballistic interference,an extended state estimator is used to compensate the output feedback according to the test ballistic angle.In order to improve the tracking efficiency and ensure the tracking error convergence with only translational motion information,the virtual guide point,whose derivative is deduced according to the Lyapunov principle,is calculated in real time according to the projection relationship between the real-time position and the reference trajectory,and a virtual line-of-sight angle and the backstepping method are used for the design of the guidance and control system.In order to avoid the influence of control input saturation on the guidance and control performance due to the actuator limitation and improve the robustness of the system,an anti-saturation compensator is designed according to the two-step method.The feasibility and effectiveness of the path-following controller is verified through closed-loop flight simulations with measurement,control,and condition uncertainties.The results indicate that the designed controller can converge to the reference path and evidently decrease the distance between the impact point and target under different uncertainties.
文摘MapReduce是一个流行的并行处理大规模数据计算模型.为提升异构环境下的MapReduce性能,提出一种异构环境下基于节点作业时间感知的动态MapReduce调度策略:DTHE(Dynamic Map Reduce scheduling based on the Time-aware of node jobs in Heterogeneous Environments).DTHE在作业执行前,首先标记部分任务作为节点样本任务并优先处理,在执行其他任务时分析样本任务,预测节点性能和数据分布特征,动态采取相应的调度策略;在作业运行中实时监测节点任务状态,提前拉取节点下一个任务数据到本地内存.实验结果表明:在异构环境下,DTEH能够缩短5.1%的作业执行时间并减少磁盘I/O,有效提升MapReduce性能.
