Piezo actuators are widely used in ultra-precision fields because of their high response and nano-scale step length.However,their hysteresis characteristics seriously affect the accuracy and stability of piezo actuato...Piezo actuators are widely used in ultra-precision fields because of their high response and nano-scale step length.However,their hysteresis characteristics seriously affect the accuracy and stability of piezo actuators.Existing methods for fitting hysteresis loops include operator class,differential equation class,and machine learning class.The modeling cost of operator class and differential equation class methods is high,the model complexity is high,and the process of machine learning,such as neural network calculation,is opaque.The physical model framework cannot be directly extracted.Therefore,the sparse identification of nonlinear dynamics(SINDy)algorithm is proposed to fit hysteresis loops.Furthermore,the SINDy algorithm is improved.While the SINDy algorithm builds an orthogonal candidate database for modeling,the sparse regression model is simplified,and the Relay operator is introduced for piecewise fitting to solve the distortion problem of the SINDy algorithm fitting singularities.The Relay-SINDy algorithm proposed in this paper is applied to fitting hysteresis loops.Good performance is obtained with the experimental results of open and closed loops.Compared with the existing methods,the modeling cost and model complexity are reduced,and the modeling accuracy of the hysteresis loop is improved.展开更多
An overview on nonlinear reconfigurable flight control approaches that have been demonstrated in flight-test or highfidelity simulation is presented. Various approaches for reconfigurable flight control systems are co...An overview on nonlinear reconfigurable flight control approaches that have been demonstrated in flight-test or highfidelity simulation is presented. Various approaches for reconfigurable flight control systems are considered, including nonlinear dynamic inversion, parameter identification and neural network technologies, backstepping and model predictive control approaches. The recent research work, flight tests, and potential strength and weakness of each approach are discussed objectively in order to give readers and researchers some reference. Finally, possible future directions and open problems in this area are addressed.展开更多
目前无监督的泛化行人重识别算法在某些需要背景信息辅助判断的情况下,可能会忽视图像的局部区域对细粒度特征的关注,导致背景信息被过滤掉,从而降低识别精度。针对上述问题,提出了一种基于稀疏注意力的动态查询感知算法。通过挤压拼接(...目前无监督的泛化行人重识别算法在某些需要背景信息辅助判断的情况下,可能会忽视图像的局部区域对细粒度特征的关注,导致背景信息被过滤掉,从而降低识别精度。针对上述问题,提出了一种基于稀疏注意力的动态查询感知算法。通过挤压拼接(squeeze and concat,SPC)模块,获取不同通道数的特征图。利用双层路由感知注意力机制,提取不同尺度特征图之间的注意力权重,得到逐级通道注意力向量。对逐级通道注意力向量的权重进行重新校准。将重新标定的权重与相应的特征图进行加权,输出具有更丰富细化特征信息的多尺度特征图。所提模型在大规模公开数据集(Market-1501、DukeMTMC-reID、MSMT17)上进行实验,相较于基线模型Rank-1分别提高了3.2、4.4、15.4个百分点,mAP分别提高了5.5、8.3、16.2个百分点,与现有前沿算法相比,能够实现更好的局部和全局特征通道之间的信息交互,提升模型对图像特征的细节感知能力.展开更多
基金National Natural Science Foundation of China(62203118)。
文摘Piezo actuators are widely used in ultra-precision fields because of their high response and nano-scale step length.However,their hysteresis characteristics seriously affect the accuracy and stability of piezo actuators.Existing methods for fitting hysteresis loops include operator class,differential equation class,and machine learning class.The modeling cost of operator class and differential equation class methods is high,the model complexity is high,and the process of machine learning,such as neural network calculation,is opaque.The physical model framework cannot be directly extracted.Therefore,the sparse identification of nonlinear dynamics(SINDy)algorithm is proposed to fit hysteresis loops.Furthermore,the SINDy algorithm is improved.While the SINDy algorithm builds an orthogonal candidate database for modeling,the sparse regression model is simplified,and the Relay operator is introduced for piecewise fitting to solve the distortion problem of the SINDy algorithm fitting singularities.The Relay-SINDy algorithm proposed in this paper is applied to fitting hysteresis loops.Good performance is obtained with the experimental results of open and closed loops.Compared with the existing methods,the modeling cost and model complexity are reduced,and the modeling accuracy of the hysteresis loop is improved.
基金supported by the National Natural Science Foundation of China (61273171)the National Aerospace Science Foundation of China (2011ZA52009)
文摘An overview on nonlinear reconfigurable flight control approaches that have been demonstrated in flight-test or highfidelity simulation is presented. Various approaches for reconfigurable flight control systems are considered, including nonlinear dynamic inversion, parameter identification and neural network technologies, backstepping and model predictive control approaches. The recent research work, flight tests, and potential strength and weakness of each approach are discussed objectively in order to give readers and researchers some reference. Finally, possible future directions and open problems in this area are addressed.
文摘目前无监督的泛化行人重识别算法在某些需要背景信息辅助判断的情况下,可能会忽视图像的局部区域对细粒度特征的关注,导致背景信息被过滤掉,从而降低识别精度。针对上述问题,提出了一种基于稀疏注意力的动态查询感知算法。通过挤压拼接(squeeze and concat,SPC)模块,获取不同通道数的特征图。利用双层路由感知注意力机制,提取不同尺度特征图之间的注意力权重,得到逐级通道注意力向量。对逐级通道注意力向量的权重进行重新校准。将重新标定的权重与相应的特征图进行加权,输出具有更丰富细化特征信息的多尺度特征图。所提模型在大规模公开数据集(Market-1501、DukeMTMC-reID、MSMT17)上进行实验,相较于基线模型Rank-1分别提高了3.2、4.4、15.4个百分点,mAP分别提高了5.5、8.3、16.2个百分点,与现有前沿算法相比,能够实现更好的局部和全局特征通道之间的信息交互,提升模型对图像特征的细节感知能力.
