As the elevator and rudder can be used actively for control,in addition to the rotors,Coaxial High-speed Helicopters(CHHs)have the problems of control redundancy and changing control authority in the transition mode.T...As the elevator and rudder can be used actively for control,in addition to the rotors,Coaxial High-speed Helicopters(CHHs)have the problems of control redundancy and changing control authority in the transition mode.This paper presents a robust-augmentation transitioning flight control design for a CHH under the adverse conditions of parametric uncertainties and external disturbances.First,based on control characteristic analysis,an Adaptive Filtered Nonlinear Dynamic Inversion(AFNDI)controller is proposed for the angular rate to handle the effect of unknown unstructured uncertainties and external turbulence.Theoretical analysis proves that the presented angular rate controller can guarantee steady-state and transient performance.Furthermore,the attitude angle and velocity controllers are also added.Then,an Incremental-based Nonlinear Prioritizing Control Allocation(INPCA)method is designed to take into account control surface transition and changing control authority,which efficiently distributes the required moments between coaxial rotors and aero-surfaces,and avoids the control reversal problem of the yaw channel.In the proposed control architecture,the low-pass filter is introduced to alleviate the adverse influence of time delay and measurement noise.Finally,the effectiveness of the proposed controller is demonstrated through nonlinear numerical simulations,and is compared with existing methods.Simulation results show that the proposed control law can improve both capabilities of disturbance rejection and fast response,and works satisfactorily for the CHH transitioning control characteristic.展开更多
A new waveguide to coaxial line transition adopted to microwave band is proposed in this paper.The configuration and design of the transition is studied. It has the merits of simplicity in structure, ease ofconstructi...A new waveguide to coaxial line transition adopted to microwave band is proposed in this paper.The configuration and design of the transition is studied. It has the merits of simplicity in structure, ease ofconstruction and repeatable performance, especially that the coaxial line is in the same direction with thewaveguide. At X band, the pass bandwidth of the transition is about 6%, and the insertion loss less than 1dB.展开更多
文摘As the elevator and rudder can be used actively for control,in addition to the rotors,Coaxial High-speed Helicopters(CHHs)have the problems of control redundancy and changing control authority in the transition mode.This paper presents a robust-augmentation transitioning flight control design for a CHH under the adverse conditions of parametric uncertainties and external disturbances.First,based on control characteristic analysis,an Adaptive Filtered Nonlinear Dynamic Inversion(AFNDI)controller is proposed for the angular rate to handle the effect of unknown unstructured uncertainties and external turbulence.Theoretical analysis proves that the presented angular rate controller can guarantee steady-state and transient performance.Furthermore,the attitude angle and velocity controllers are also added.Then,an Incremental-based Nonlinear Prioritizing Control Allocation(INPCA)method is designed to take into account control surface transition and changing control authority,which efficiently distributes the required moments between coaxial rotors and aero-surfaces,and avoids the control reversal problem of the yaw channel.In the proposed control architecture,the low-pass filter is introduced to alleviate the adverse influence of time delay and measurement noise.Finally,the effectiveness of the proposed controller is demonstrated through nonlinear numerical simulations,and is compared with existing methods.Simulation results show that the proposed control law can improve both capabilities of disturbance rejection and fast response,and works satisfactorily for the CHH transitioning control characteristic.
文摘A new waveguide to coaxial line transition adopted to microwave band is proposed in this paper.The configuration and design of the transition is studied. It has the merits of simplicity in structure, ease ofconstruction and repeatable performance, especially that the coaxial line is in the same direction with thewaveguide. At X band, the pass bandwidth of the transition is about 6%, and the insertion loss less than 1dB.
