The aim of this study was to develop robust tracking control schemes for the 3D leap trajectory of hypersonic gliding vehicles using sliding mode theory. A predictor-corrector guidance method was applied to the genera...The aim of this study was to develop robust tracking control schemes for the 3D leap trajectory of hypersonic gliding vehicles using sliding mode theory. A predictor-corrector guidance method was applied to the generation of the reference trajectory, and drag acceleration was selected as the profile of reference tracking. A combined super-twisting sliding mode controller(CST-SMC) is proposed to decrease the tracking error and guarantee the tracking performance in the presence of system nonlinearities compared to three other common controllers: the linear sliding mode controller(L-SMC), global fast terminal sliding mode controller(GFT-SMC), and super-twisting sliding mode controller(ST-SMC). By using the developed controller, the system state of a second-order drag acceleration tracking error system can approach the global fast terminal sliding manifold in finite time. By using the Lyapunov approach, sufficient conditions are deduced to ensure that the tracking performance is obtained for a closed-loop system. Furthermore, we show that the controller is robust to initial uncertain parameters and other perturbations, as validated by simulation results with appropriate gains.展开更多
Nowadays,the increasing electromagnetic waves generated by wearable devices are becoming an emerging issue for human health,so stretchable electromagnetic interference(EMI)shielding materials are highly demanded.Eleph...Nowadays,the increasing electromagnetic waves generated by wearable devices are becoming an emerging issue for human health,so stretchable electromagnetic interference(EMI)shielding materials are highly demanded.Elephant trunks are capable of grabbing fragile vegetation and tearing trees thanks not only to their muscles but also to their folded skins.Inspired by the wrinkled skin of the elephant trunks,herein,we propose a winkled conductive film based on single-walled carbon nanotubes(SWCNTs)for multifunctional EMI applications.The conductive film has a sandwich structure,which was prepared by coating SWCNTs on both sides of the stretched elastic latex cylindrical substrate.The shrinking-induced winkled conductive network could withstand up to 200%tensile strain.Typically,when the stretching direction is parallel to the polarization direction of the electric field,the total EMI shielding effectiveness could surprisingly increase from 38.4 to 52.7 dB at 200%tensile strain.It is mainly contributed by the increased connection of the SWCNTs.In addition,the film also has good Joule heating performance at several voltages,capable of releasing pains in injured joints.This unique property makes it possible for strain-adjustable multifunctional EMI shielding and wearable thermotherapy applications.展开更多
基金supported by the National Natural Science Foundation of China (No. 11972368)the Natural Science Foundation of Hunan Province (No. 2021JJ10045), China。
文摘The aim of this study was to develop robust tracking control schemes for the 3D leap trajectory of hypersonic gliding vehicles using sliding mode theory. A predictor-corrector guidance method was applied to the generation of the reference trajectory, and drag acceleration was selected as the profile of reference tracking. A combined super-twisting sliding mode controller(CST-SMC) is proposed to decrease the tracking error and guarantee the tracking performance in the presence of system nonlinearities compared to three other common controllers: the linear sliding mode controller(L-SMC), global fast terminal sliding mode controller(GFT-SMC), and super-twisting sliding mode controller(ST-SMC). By using the developed controller, the system state of a second-order drag acceleration tracking error system can approach the global fast terminal sliding manifold in finite time. By using the Lyapunov approach, sufficient conditions are deduced to ensure that the tracking performance is obtained for a closed-loop system. Furthermore, we show that the controller is robust to initial uncertain parameters and other perturbations, as validated by simulation results with appropriate gains.
基金financially supported by the National Natural Science Foundation of China(52073302,52103311)Hunan Provincial Natural Science Foundation for Distinguished Young Scholars(No.14JJ1001).
文摘Nowadays,the increasing electromagnetic waves generated by wearable devices are becoming an emerging issue for human health,so stretchable electromagnetic interference(EMI)shielding materials are highly demanded.Elephant trunks are capable of grabbing fragile vegetation and tearing trees thanks not only to their muscles but also to their folded skins.Inspired by the wrinkled skin of the elephant trunks,herein,we propose a winkled conductive film based on single-walled carbon nanotubes(SWCNTs)for multifunctional EMI applications.The conductive film has a sandwich structure,which was prepared by coating SWCNTs on both sides of the stretched elastic latex cylindrical substrate.The shrinking-induced winkled conductive network could withstand up to 200%tensile strain.Typically,when the stretching direction is parallel to the polarization direction of the electric field,the total EMI shielding effectiveness could surprisingly increase from 38.4 to 52.7 dB at 200%tensile strain.It is mainly contributed by the increased connection of the SWCNTs.In addition,the film also has good Joule heating performance at several voltages,capable of releasing pains in injured joints.This unique property makes it possible for strain-adjustable multifunctional EMI shielding and wearable thermotherapy applications.
