Guidance path-planning and following are two core technologies used for controlling un-manned aerial vehicles(UAVs)in both military and civilian applications.However,only a few approaches treat both the technologies s...Guidance path-planning and following are two core technologies used for controlling un-manned aerial vehicles(UAVs)in both military and civilian applications.However,only a few approaches treat both the technologies simultaneously.In this study,an innovative hybrid gradient vector fields for path-following guidance(HGVFs-PFG)algorithm is proposed to control fixed-wing UAVs to follow a generated guidance path and oriented target curves in three-dimensional space,which can be any combination of straight lines,arcs,and helixes as motion primitives.The algorithm aids the creation of vector fields(VFs)for these motion primitives as well as the design of an effective switching strategy to ensure that only one VF is activated at any time to ensure that the complex paths are followed completely.The strategies designed in earlier studies have flaws that prevent the UAV from following arcs that make its turning angle too large.The proposed switching strategy solves this problem by introducing the concept of the virtual way-points.Finally,the performance of the HGVFs-PFG algorithm is verified using a reducedorder autopilot and four representative simulation scenarios.The simulation considers the constraints of the aircraft,and its results indicate that the algorithm performs well in following both lateral and longitudinal control,particularly for curved paths.In general,the proposed technical method is practical and competitive.展开更多
为了克服VFC(vector field convolution)Snake模型对图像弱边界的泄露问题,对其作了两点改进:a)重新定义了向量场核的模,有效降低了VFC外力对向量模参数的敏感性;b)综合利用VFC外力和图像势能力,给出动态VFC外力。随着模型曲线的形变,...为了克服VFC(vector field convolution)Snake模型对图像弱边界的泄露问题,对其作了两点改进:a)重新定义了向量场核的模,有效降低了VFC外力对向量模参数的敏感性;b)综合利用VFC外力和图像势能力,给出动态VFC外力。随着模型曲线的形变,不断调整外力,使得曲线精确定位到目标边界上。最后通过实验证明了改进后的VFC Snake模型对噪声具有鲁棒性、对参数变化不敏感,且能够收敛到图像弱边界处。展开更多
基金the support of the National Natural Science Foundation of China under Grant No.62076204 and Grant No.62006193in part by the Postdoctoral Science Foundation of China under Grants No.2021M700337in part by the Fundamental Research Funds for the Central Universities under Grant No.3102019ZX016。
文摘Guidance path-planning and following are two core technologies used for controlling un-manned aerial vehicles(UAVs)in both military and civilian applications.However,only a few approaches treat both the technologies simultaneously.In this study,an innovative hybrid gradient vector fields for path-following guidance(HGVFs-PFG)algorithm is proposed to control fixed-wing UAVs to follow a generated guidance path and oriented target curves in three-dimensional space,which can be any combination of straight lines,arcs,and helixes as motion primitives.The algorithm aids the creation of vector fields(VFs)for these motion primitives as well as the design of an effective switching strategy to ensure that only one VF is activated at any time to ensure that the complex paths are followed completely.The strategies designed in earlier studies have flaws that prevent the UAV from following arcs that make its turning angle too large.The proposed switching strategy solves this problem by introducing the concept of the virtual way-points.Finally,the performance of the HGVFs-PFG algorithm is verified using a reducedorder autopilot and four representative simulation scenarios.The simulation considers the constraints of the aircraft,and its results indicate that the algorithm performs well in following both lateral and longitudinal control,particularly for curved paths.In general,the proposed technical method is practical and competitive.
文摘为了克服VFC(vector field convolution)Snake模型对图像弱边界的泄露问题,对其作了两点改进:a)重新定义了向量场核的模,有效降低了VFC外力对向量模参数的敏感性;b)综合利用VFC外力和图像势能力,给出动态VFC外力。随着模型曲线的形变,不断调整外力,使得曲线精确定位到目标边界上。最后通过实验证明了改进后的VFC Snake模型对噪声具有鲁棒性、对参数变化不敏感,且能够收敛到图像弱边界处。
