Stability Analysis And Control Research Of Cicada-Like Flapping Wing Micro Aerial Vehicle

Bionic flapping wing micro aerial vehicle(FWMAV)is a new type of aircraft developed by imitating the flight mode of bats,birds and insects in nature.It can fly in highly complex and dynamic environment and has good robustness to environmental interference.It is one of the important research directions in the future development of robotics field.Taking cicada as the research object,the key problems of aerodynamics,rigid body dynamics,stability and control of near hovering flight are studied.The main research contents of this thesis are as follows:(1)Based on the current research gap,a cicada-like four-wing FWMAV is proposed.Based on the quasi-steady-state blade element method,the aerodynamic modeling of the translational force,rotational force and additional mass force of the FWMAV was carried out.Based on the rigid body modeling,the dynamic equation of the FWMAV was given.Based on the hovering conditions of the FWMAV,the nonlinear longitudinal and transverse dynamics models of the FWMAV were obtained.The above nonlinear dynamics model is simplified to linear dynamics model under the condition of small disturbance.The results show that the FWMAV can be divided into four independent subsystems: pitch subsystem,roll subsystem,yaw subsystem and vertical subsystem.(2)The mathematical expressions of stability derivatives of pitch dynamics,roll dynamics,yaw dynamics and vertical dynamics of the CL-FWMAV under the disturbance of external forces and external moments are given for the first time.The effects of longitudinal position,vertical position and fuselage width on hover flight stability are analyzed theoretically for the first time,and the position of wing and fuselage width are given.The results show that the pitch subsystem and the roll system of the CL-FWMAV have inherent instability,but can be stabilized by simple rate feedback.The vertical subsystem and roll subsystem of the CL-FWMAV are inherently stable.The width of the fuselage has no effect on the stability of the pitching dynamics.However,the closer the longitudinal position of the wing root of the front and rear aircraft is to the center of gravity,the more favorable the pitch dynamics stability of the body.The longitudinal position of the wing root has no effect on the stability of the roll dynamics,and the wider the width of the fuselage,the more conducive to the roll dynamics stability of the body,which explains the reason for the wider thorax of the cicada.The vertical dynamics is always stable,and has nothing to do with the longitudinal and transverse positions of the wing root and the width of the fuselage,but is only related to the wing kinematics.The yaw dynamics are also stable and independent of the longitudinal position of the wing root.(3)Based on computational fluid dynamics simulation,the trim state of the wing of the CL-FWMAV was found.Based on the calculated stability derivative,a cascade PID controller is designed,which can not only stabilize the flight,but also effectively track the input.The inner loop controller of pitch subsystem and roll system,the controller of vertical subsystem and yaw subsystem were replaced with ADRC controller.The interference suppression ability of pitch subsystem and roll subsystem under the interference of external force and external torque noise was compared with the original controller.The results show that the interference can be effectively suppressed in the inner loop after the introduction of ADRC controller for yaw subsystem and roll subsystem.However,the dynamic performance of the intermediate loop and the outer loop will be reduced.When the controller of vertical subsystem and yaw subsystem is replaced by ADRC controller,the interference can be suppressed effectively and the dynamic performance of the system can be improved.The generation mode of vertical force and moment based on flap frequency of the four-wing aircraft is given.Based on the simulation data,the control derivatives of vertical force,roll moment,pitch moment and yaw moment of the four-wing aircraft on flap frequency are derived for the first time.Based on the control derivatives,the necessary flap frequency for realizing straight flight,yaw,roll and pitch when the flapping wing is hovering near is obtained.