Aiming at the position and attitude tracking of coaxial rotor aircraft(CRA),this paper proposes a combinatorial control method of sliding mode control(SMC)coupled with proportional-integralderivative control(PIDC).Con...Aiming at the position and attitude tracking of coaxial rotor aircraft(CRA),this paper proposes a combinatorial control method of sliding mode control(SMC)coupled with proportional-integralderivative control(PIDC).Considering the complete description of flight dynamics,aerodynamics and airflow interference,the dynamical model of CRA is established.The dynamical model is simplified according to the actual flight,then the simplified dynamical model is divided into two subsystems:a fully-actuated subsystem and an under-actuated subsystem.The controller of the fully-actuated subsystem consists of a SMC controller coupled with a rate bounded PIDC controller,while the controller of the under-actuated subsystem is composed of a SMC controller.The sliding manifold is defined by combining the position and velocity tracking errors of the state variables for each subsystem.Lyapunov stability theory is used to verify the stability of the sliding mode controller,which ensures that all state trajectories of the system can reach and stay on the sliding mode surface,the uncertainty and external interference of the model are compensated.Simulation and experiment compared with the conventional PIDC are carried out,the results demonstrate the effectiveness and the robustness of the proposed control method of this paper.展开更多
The original free vortex wake model was used for numerical investigation.Calculation of the aerodynamic characteristics in hover and vertical descent modes in the range of vertical descent speed of 0–30 m/s including...The original free vortex wake model was used for numerical investigation.Calculation of the aerodynamic characteristics in hover and vertical descent modes in the range of vertical descent speed of 0–30 m/s including the Vortex Ring State(VRS)area was performed.The calculations were carried out under the condition of variable blade pitch angle values providing a fixed timeaverage thrust value.Visualization data of free vortex wake shapes,flow structures,and velocity fields were obtained and analyzed.The time-dependences of the rotor’s thrust and torque coefficients were obtained and analyzed.The obtained data allows determining the boundaries of the VRS area by various criteria such as rotor thrust and torque pulsations,growth of rotor power consumption relative to the hover,growth of rotor induced velocities relative to the hover,and growth of the required rotor blade pitch angles values.The results of the study are compared with experimental and calculated data of other authors and can significantly supplement the available results of experimental and computational studies in this area.展开更多
Flight dynamics modeling for the Mars helicopter faces great challenges.Aerodynamic modeling of coaxial rotor with high confidence and high computational efficiency is a major difficulty for the field.This paper build...Flight dynamics modeling for the Mars helicopter faces great challenges.Aerodynamic modeling of coaxial rotor with high confidence and high computational efficiency is a major difficulty for the field.This paper builds an aerodynamic model of coaxial rotor in the extremely thin Martian atmosphere using the viscous vortex particle method.The aerodynamic forces and flow characteristics of rigid coaxial rotor are computed and analyzed.Meanwhile,a high fidelity aerodynamic surrogate model is built to improve the computational efficiency of the flight dynamics model.Results in this paper reveal that rigid coaxial rotor can bring the Mars helicopter sufficient controllability but result in obvious instability and control couplings in forward flight.This highlights the great differences in flight dynamics characteristics compared with conventional helicopters on Earth.展开更多
基金supported by National Natural Science Founda-tion of china(Grant No.51774042).
文摘Aiming at the position and attitude tracking of coaxial rotor aircraft(CRA),this paper proposes a combinatorial control method of sliding mode control(SMC)coupled with proportional-integralderivative control(PIDC).Considering the complete description of flight dynamics,aerodynamics and airflow interference,the dynamical model of CRA is established.The dynamical model is simplified according to the actual flight,then the simplified dynamical model is divided into two subsystems:a fully-actuated subsystem and an under-actuated subsystem.The controller of the fully-actuated subsystem consists of a SMC controller coupled with a rate bounded PIDC controller,while the controller of the under-actuated subsystem is composed of a SMC controller.The sliding manifold is defined by combining the position and velocity tracking errors of the state variables for each subsystem.Lyapunov stability theory is used to verify the stability of the sliding mode controller,which ensures that all state trajectories of the system can reach and stay on the sliding mode surface,the uncertainty and external interference of the model are compensated.Simulation and experiment compared with the conventional PIDC are carried out,the results demonstrate the effectiveness and the robustness of the proposed control method of this paper.
文摘The original free vortex wake model was used for numerical investigation.Calculation of the aerodynamic characteristics in hover and vertical descent modes in the range of vertical descent speed of 0–30 m/s including the Vortex Ring State(VRS)area was performed.The calculations were carried out under the condition of variable blade pitch angle values providing a fixed timeaverage thrust value.Visualization data of free vortex wake shapes,flow structures,and velocity fields were obtained and analyzed.The time-dependences of the rotor’s thrust and torque coefficients were obtained and analyzed.The obtained data allows determining the boundaries of the VRS area by various criteria such as rotor thrust and torque pulsations,growth of rotor power consumption relative to the hover,growth of rotor induced velocities relative to the hover,and growth of the required rotor blade pitch angles values.The results of the study are compared with experimental and calculated data of other authors and can significantly supplement the available results of experimental and computational studies in this area.
基金supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions,China.
文摘Flight dynamics modeling for the Mars helicopter faces great challenges.Aerodynamic modeling of coaxial rotor with high confidence and high computational efficiency is a major difficulty for the field.This paper builds an aerodynamic model of coaxial rotor in the extremely thin Martian atmosphere using the viscous vortex particle method.The aerodynamic forces and flow characteristics of rigid coaxial rotor are computed and analyzed.Meanwhile,a high fidelity aerodynamic surrogate model is built to improve the computational efficiency of the flight dynamics model.Results in this paper reveal that rigid coaxial rotor can bring the Mars helicopter sufficient controllability but result in obvious instability and control couplings in forward flight.This highlights the great differences in flight dynamics characteristics compared with conventional helicopters on Earth.
