To overcome the influence of the nonlinear friction on the gimbaled servo-system of an inertial stabilized platforms(ISPs)with DC motor direct-drive,the methods of modeling and compensation of the nonlinear friction a...To overcome the influence of the nonlinear friction on the gimbaled servo-system of an inertial stabilized platforms(ISPs)with DC motor direct-drive,the methods of modeling and compensation of the nonlinear friction are proposed.Firstly,the inapplicability of LuGre model when trying to interpret the backward angular displacement in the prestiction regime is observed experimentally and the reason is deduced theoretically.Then,based on the dynamic model of direct-drive ISPs,a modified LuGre model is proposed to describe the characteristic of the friction in the prestiction regime.Furthermore,the state switch condition of the three friction regimes including presliding,gross sliding and prestiction is presented.Finally,a composite compensation controller including a nonlinear friction observer and a feedforward compensator based on the novel LuGre model is designed to restrain the nonlinear friction and to improve the control precision.Experimental results indicate that compared with those of the conventional proportion-integrationdifferentiation(PID)control method and the PID plus LuGre model-based friction compensation method,the dwell-time has decreased from 0.2 s to almost 0 s,the position error decreased to 86.7%and the peak-to-peak value of position error decreased to 80%after the novel compensation controller is added.It concludes that the composite compensation controller can greatly improve the control precision of the dynamic sealed ISPs.展开更多
The development of a tailless Flapping Wing Micro Aerial Vehicle(FWMAV)inspired by the hummingbird is presented in this work.By implementing mechanical simplifications,it is possible to use planar machining technology...The development of a tailless Flapping Wing Micro Aerial Vehicle(FWMAV)inspired by the hummingbird is presented in this work.By implementing mechanical simplifications,it is possible to use planar machining technology for manufacturing of the FWMAV’s body,greatly reducing assembly errors.Traditionally,studies on flapping wing aircraft are limited to open-loop wing kinematics control.In this work,an instantaneous closed-loop wing trajectory tracking control system is introduced to minimize wings’trajectory tracking errors.The control system is based on Field-Oriented Control(FOC)with a loop shaping compensation technique near the flapping frequency.Through frequency analysis,the loop shaping compensator ensures the satisfactory bandwidth and performance for the closed-loop flapping system.To implement the proposed controller,a compact autopilot board integrated with FOC hardware is designed,weighing only 2.5 g.By utilizing precise wing trajectory tracking control,the hummingbird-inspired FWMAV demonstrates superior ability to resist external disturbances and exhibits reduced attitude tracking errors during hovering flight compared to the open-loop wing motion.展开更多
基金co-supported by the National Natural Science Foundation of China(Nos.51135009 and 51105371)
文摘To overcome the influence of the nonlinear friction on the gimbaled servo-system of an inertial stabilized platforms(ISPs)with DC motor direct-drive,the methods of modeling and compensation of the nonlinear friction are proposed.Firstly,the inapplicability of LuGre model when trying to interpret the backward angular displacement in the prestiction regime is observed experimentally and the reason is deduced theoretically.Then,based on the dynamic model of direct-drive ISPs,a modified LuGre model is proposed to describe the characteristic of the friction in the prestiction regime.Furthermore,the state switch condition of the three friction regimes including presliding,gross sliding and prestiction is presented.Finally,a composite compensation controller including a nonlinear friction observer and a feedforward compensator based on the novel LuGre model is designed to restrain the nonlinear friction and to improve the control precision.Experimental results indicate that compared with those of the conventional proportion-integrationdifferentiation(PID)control method and the PID plus LuGre model-based friction compensation method,the dwell-time has decreased from 0.2 s to almost 0 s,the position error decreased to 86.7%and the peak-to-peak value of position error decreased to 80%after the novel compensation controller is added.It concludes that the composite compensation controller can greatly improve the control precision of the dynamic sealed ISPs.
基金support by the National Natural Science Foundation of China(No.62073217,No.61871266)the Fund of the Ministry of Education of the People’s Republic of China(6141A02022607,6141A020227)the Fund of the Professional Technical Service Platform of Shanghai(19DZ2291103).
文摘The development of a tailless Flapping Wing Micro Aerial Vehicle(FWMAV)inspired by the hummingbird is presented in this work.By implementing mechanical simplifications,it is possible to use planar machining technology for manufacturing of the FWMAV’s body,greatly reducing assembly errors.Traditionally,studies on flapping wing aircraft are limited to open-loop wing kinematics control.In this work,an instantaneous closed-loop wing trajectory tracking control system is introduced to minimize wings’trajectory tracking errors.The control system is based on Field-Oriented Control(FOC)with a loop shaping compensation technique near the flapping frequency.Through frequency analysis,the loop shaping compensator ensures the satisfactory bandwidth and performance for the closed-loop flapping system.To implement the proposed controller,a compact autopilot board integrated with FOC hardware is designed,weighing only 2.5 g.By utilizing precise wing trajectory tracking control,the hummingbird-inspired FWMAV demonstrates superior ability to resist external disturbances and exhibits reduced attitude tracking errors during hovering flight compared to the open-loop wing motion.
