载人航天器的防护要求不断增强,在轨泄漏检测的重要性日益凸现。文章阐述了航天器在轨泄漏声发射检测的基本原理,介绍了泄漏检测系统的基本组成及性能参数。通过泄漏声发射检测实验,利用频谱分析法和特征参数分析法对不同孔径圆形漏孔...载人航天器的防护要求不断增强,在轨泄漏检测的重要性日益凸现。文章阐述了航天器在轨泄漏声发射检测的基本原理,介绍了泄漏检测系统的基本组成及性能参数。通过泄漏声发射检测实验,利用频谱分析法和特征参数分析法对不同孔径圆形漏孔泄漏产生的声发射信号进行研究,得到了泄漏声发射信号的频谱和特征参数。实验结果表明,机械泵运行产生的背景噪声信号主要分布在10 k Hz以下,而气体泄漏产生的是高频声发射信号,且漏孔越小,信号能量越小,高频成分所占比例越大。该研究对于航天器在轨泄漏的检测及泄漏量评估等具有实际意义。展开更多
Conventional sliding mode control(SMC)has been extensively applied in controlling spacecrafts because of its appealing characteristics such as robustness and a simple design procedure.Several methods such as second-or...Conventional sliding mode control(SMC)has been extensively applied in controlling spacecrafts because of its appealing characteristics such as robustness and a simple design procedure.Several methods such as second-order sliding modes and discontinuous controllers are applied for the SMC implementation.However,the main problems of these methods are convergence and error tracking in a finite amount of time.This paper combines an improved dynamic sliding mode controller and model predictive controller for spacecrafts to solve the chattering phenomenon in traditional sliding mode control.To this aim,this paper develops dynamic sliding mode control for spacecraft’s applications to omit the chattering issue.The proposed approach shows robust attitude tracking by a set of reaction wheels and stabilizes the spacecraft subject to disturbances and uncertainties.The proposed method improves the performance of the SMC for spacecraft by avoiding chattering.A set of simulation results are provided that show the advantages and improvements of this approach(in some sense)compared to SMC approaches.展开更多
文摘载人航天器的防护要求不断增强,在轨泄漏检测的重要性日益凸现。文章阐述了航天器在轨泄漏声发射检测的基本原理,介绍了泄漏检测系统的基本组成及性能参数。通过泄漏声发射检测实验,利用频谱分析法和特征参数分析法对不同孔径圆形漏孔泄漏产生的声发射信号进行研究,得到了泄漏声发射信号的频谱和特征参数。实验结果表明,机械泵运行产生的背景噪声信号主要分布在10 k Hz以下,而气体泄漏产生的是高频声发射信号,且漏孔越小,信号能量越小,高频成分所占比例越大。该研究对于航天器在轨泄漏的检测及泄漏量评估等具有实际意义。
文摘Conventional sliding mode control(SMC)has been extensively applied in controlling spacecrafts because of its appealing characteristics such as robustness and a simple design procedure.Several methods such as second-order sliding modes and discontinuous controllers are applied for the SMC implementation.However,the main problems of these methods are convergence and error tracking in a finite amount of time.This paper combines an improved dynamic sliding mode controller and model predictive controller for spacecrafts to solve the chattering phenomenon in traditional sliding mode control.To this aim,this paper develops dynamic sliding mode control for spacecraft’s applications to omit the chattering issue.The proposed approach shows robust attitude tracking by a set of reaction wheels and stabilizes the spacecraft subject to disturbances and uncertainties.The proposed method improves the performance of the SMC for spacecraft by avoiding chattering.A set of simulation results are provided that show the advantages and improvements of this approach(in some sense)compared to SMC approaches.
