A novel gain-scheduled switching control method for the longitudinal motion of a flexible air-breathing hypersonic vehicle （FAHV） is proposed. Firstly, velocity and altitude are selected as scheduling variables, a p...A novel gain-scheduled switching control method for the longitudinal motion of a flexible air-breathing hypersonic vehicle （FAHV） is proposed. Firstly, velocity and altitude are selected as scheduling variables, a polytopic linear parameter varying （LPV） model is developed to represent the complex nonlinear longitudinal dynamics of the FAHV. Secondly, based on the obtained polytopic LPV model, the flight envelope is divided into four smaller subregions, and four gain-scheduled controllers are designed for these parameter subregions. Then, by the defined switching characteristic function, these gain-scheduled controllers are switched in order to guarantee the closed-loop FAHV system to be asymptotically stable and satisfy a given tracking error performance criterion. The condition of gain-scheduled switching controller synthesis is given in terms of linear matrix inequalities （LMIs） which can be easily solved by using standard software packages. Finally, simulation results show the effectiveness of the presented method.展开更多
A robust sliding mode approach combined with a field oriented control （FOC） for induction motor （IM） speed control is presented. The proposed sliding mode control （SMC） design uses an adaptive switching gain and...A robust sliding mode approach combined with a field oriented control （FOC） for induction motor （IM） speed control is presented. The proposed sliding mode control （SMC） design uses an adaptive switching gain and an integrator. This approach guarantees the same robustness and dynamic performance of traditional SMC algorithms. And at the same time, it attenuates the chattering phenomenon, which is the main drawback in actual implementation of this technique. This approach is insensitive to uncertainties and permits to decrease the requirement for the bound of these uncertainties. The stability and robustness of the closed- loop system are proven analytically using the Lyapunov synthesis approach. The proposed method attenuates the effect of both uncertainties and external disturbances. Experimental results are presented to validate the effectiveness and the good performance of the developed method.展开更多
The generation of high-power laser pulses using a compact hetero-integrated assembly based on a semiconductor laser with a dual-element composite 2μm×100μm aperture and a compact heterothyristor switch is demon...The generation of high-power laser pulses using a compact hetero-integrated assembly based on a semiconductor laser with a dual-element composite 2μm×100μm aperture and a compact heterothyristor switch is demonstrated.The achieved peak optical power was 33 W with a pulse duration of 3 ns at a thyristor operating voltage of 55 V.The leading edge of the laser pulse turn-on was 50 ps to a power level of 24.7 W,and the turn-on delay between the elements of the composite aperture was 160 ps.展开更多
Mid-infrared(MIR)fiber pulsed lasers are of tremendous application interest in eye-safe LIDAR,spectroscopy,chemical detection and medicine.So far,these MIR lasers largely required bulk optical elements,complex free-sp...Mid-infrared(MIR)fiber pulsed lasers are of tremendous application interest in eye-safe LIDAR,spectroscopy,chemical detection and medicine.So far,these MIR lasers largely required bulk optical elements,complex free-space light alignment and large footprint,precluding compact all-fiber structure.Here,we proposed and demonstrated an all-fiberized structured gain-switched Ho3+-doped ZBLAN fiber laser operating around 2.9μm.A home-made 1146 nm Raman fiber pulsed laser was utilized to pump highly concentrated single-cladding Ho3+-doped ZBLAN fiber with different lengths of 2 m or 0.25 m.A home-made MIR fiber mirror and a perpendicular-polished ZBLAN fiber end construct the all-fiberized MIR cavity.Stable gain-switched multiple states with a sub-pulse number tuned from 1 to 8 were observed.The effects of gain fiber length,pump power,pump repetition rate and output coupling ratio on performance of gain-switched pulses were further investigated in detail.The shortest pulse duration of 283 ns was attained with 10 kHz repetition rate.The pulsed laser,centered at 2.92μm,had a maximum average output power of 54.2 mW and a slope efficiency of 10.12%.It is,to the best of our knowledge,the first time to demonstrate a mid-infrared gain-switched Ho3+:ZBLAN fiber laser with compact all-fiber structure.展开更多
基金supported by the National Outstanding Youth Science Foundation(61125306)the National Natural Science Foundation of Major Research Plan(91016004+2 种基金61034002)the Specialized Research Fund for the Doctoral Program of Higher Education of China (20110092110020)the Scientific Research Foundation of Graduate School of Southeast University(YBJJ1103)
文摘A novel gain-scheduled switching control method for the longitudinal motion of a flexible air-breathing hypersonic vehicle （FAHV） is proposed. Firstly, velocity and altitude are selected as scheduling variables, a polytopic linear parameter varying （LPV） model is developed to represent the complex nonlinear longitudinal dynamics of the FAHV. Secondly, based on the obtained polytopic LPV model, the flight envelope is divided into four smaller subregions, and four gain-scheduled controllers are designed for these parameter subregions. Then, by the defined switching characteristic function, these gain-scheduled controllers are switched in order to guarantee the closed-loop FAHV system to be asymptotically stable and satisfy a given tracking error performance criterion. The condition of gain-scheduled switching controller synthesis is given in terms of linear matrix inequalities （LMIs） which can be easily solved by using standard software packages. Finally, simulation results show the effectiveness of the presented method.
文摘A robust sliding mode approach combined with a field oriented control （FOC） for induction motor （IM） speed control is presented. The proposed sliding mode control （SMC） design uses an adaptive switching gain and an integrator. This approach guarantees the same robustness and dynamic performance of traditional SMC algorithms. And at the same time, it attenuates the chattering phenomenon, which is the main drawback in actual implementation of this technique. This approach is insensitive to uncertainties and permits to decrease the requirement for the bound of these uncertainties. The stability and robustness of the closed- loop system are proven analytically using the Lyapunov synthesis approach. The proposed method attenuates the effect of both uncertainties and external disturbances. Experimental results are presented to validate the effectiveness and the good performance of the developed method.
文摘The generation of high-power laser pulses using a compact hetero-integrated assembly based on a semiconductor laser with a dual-element composite 2μm×100μm aperture and a compact heterothyristor switch is demonstrated.The achieved peak optical power was 33 W with a pulse duration of 3 ns at a thyristor operating voltage of 55 V.The leading edge of the laser pulse turn-on was 50 ps to a power level of 24.7 W,and the turn-on delay between the elements of the composite aperture was 160 ps.
基金National Natural Science Foundation of China(Nos.61475129,11674269)Fundamental Research Funds for the Central Universities(No.20720180057)Natural Science Foundation of Fujian Province for Distinguished Young Scientists(No.2017J06016)。
文摘Mid-infrared(MIR)fiber pulsed lasers are of tremendous application interest in eye-safe LIDAR,spectroscopy,chemical detection and medicine.So far,these MIR lasers largely required bulk optical elements,complex free-space light alignment and large footprint,precluding compact all-fiber structure.Here,we proposed and demonstrated an all-fiberized structured gain-switched Ho3+-doped ZBLAN fiber laser operating around 2.9μm.A home-made 1146 nm Raman fiber pulsed laser was utilized to pump highly concentrated single-cladding Ho3+-doped ZBLAN fiber with different lengths of 2 m or 0.25 m.A home-made MIR fiber mirror and a perpendicular-polished ZBLAN fiber end construct the all-fiberized MIR cavity.Stable gain-switched multiple states with a sub-pulse number tuned from 1 to 8 were observed.The effects of gain fiber length,pump power,pump repetition rate and output coupling ratio on performance of gain-switched pulses were further investigated in detail.The shortest pulse duration of 283 ns was attained with 10 kHz repetition rate.The pulsed laser,centered at 2.92μm,had a maximum average output power of 54.2 mW and a slope efficiency of 10.12%.It is,to the best of our knowledge,the first time to demonstrate a mid-infrared gain-switched Ho3+:ZBLAN fiber laser with compact all-fiber structure.
